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. 2022 Mar 3;10(3):600. doi: 10.3390/biomedicines10030600

Human Serum Proteins and Susceptibility of Acinetobacter baumannii to Cefiderocol: Role of Iron Transport

Casin Le 1,†, Camila Pimentel 1,†, Fernando Pasteran 2, Marisel R Tuttobene 3,4, Tomás Subils 5, Jenny Escalante 1, Brent Nishimura 1, Susana Arriaga 1, Aimee Carranza 1, Vyanka Mezcord 1, Alejandro J Vila 4,6, Alejandra Corso 2, Luis A Actis 7, Marcelo E Tolmasky 1, Robert A Bonomo 8,9,10,*, Maria Soledad Ramírez 1,*
Editor: Amedeo Amedei
PMCID: PMC8945497  PMID: 35327400

Abstract

Cefiderocol, a recently introduced antibiotic, has a chemical structure that includes a cephalosporin that targets cell wall synthesis and a chlorocatechol siderophore moiety that facilitates cell penetration by active iron transporters. Analysis of the effect that human serum, human serum albumin, and human pleural fluid had on growing Acinetobacter baumannii showed that genes related to iron uptake were down-regulated. At the same time, β-lactamase genes were expressed at higher levels. The minimum inhibitory concentrations of this antimicrobial in A. baumannii cells growing in the presence of human serum, human serum albumin, or human pleural fluid were higher than those measured when these fluids were absent from the culture medium. These results correlate with increased expression levels of β-lactamase genes and the down-regulation of iron uptake-related genes in cultures containing human serum, human serum albumin, or human pleural fluid. These modifications in gene expression could explain the less-than-ideal clinical response observed in patients with pulmonary or bloodstream A. baumannii infections. The exposure of the infecting cells to the host’s fluids could cause reduced cefiderocol transport capabilities and increased resistance to β-lactams. The regulation of genes that could impact the A. baumannii susceptibility to cefiderocol, or other antibacterials, is an understudied phenomenon that merits further investigation.

Keywords: Acinetobacter baumannii, cefiderocol, human fluids, iron, human serum albumin

1. Introduction

Carbapenem-resistant Acinetobacter baumannii (CRAB), one of the most feared pathogens in healthcare settings, has been categorized by the Centers for Disease Control and Prevention (CDC) as an “urgent threat” [1,2,3,4,5]. As a consequence of A. baumannii’s ability to develop multidrug resistance (MDR), treatment strategies have become extremely limited, with only a few active antibiotics in existence [6,7,8].

The increasing number of CRAB infections translates into alarmingly high morbidity and mortality [2,9,10,11]. Consequently, numerous efforts are focusing on finding novel treatment options [12,13,14,15,16,17,18,19]. Cefiderocol (CFDC) was approved by the Food and Drug Administration of the United States (FDA) in November 2019 to treat nosocomial pneumonia and urinary tract infections (Available online: https://www.accessdata.fda.gov/drugsatfda_docs/label/2019/209445s000lbl.pdf (accessed on 14 February 2022)) [20]. CFDC is a hybrid molecule that consists of a cephalosporin component that targets cell wall synthesis and a catechol siderophore moiety that allows cell penetration by active ferric-siderophore transporters [21,22,23,24,25]. This novel synthetic compound uses a “Trojan horse” strategy to improve antibiotic penetration and reach a high concentration at the target site [22,23]. This strategy allows the drug to enter the bacterial cells using active iron transporters. In A. baumannii, the most well-characterized iron transporters are bauA, bfnH, and fbsN, which are coupled to a TonB system to translocate the siderophore–iron complex into the periplasm [26]. However, up to 21 putative TonB-dependent outer membrane transporter genes have been identified or predicted in A. baumannii genomes, most often associated with putative or confirmed ferric-siderophore and heme uptake genes [27]. The bauA gene, which encodes for the major outer membrane receptor of ferric–acinetobactin complexes, was extensively studied in A. baumannii and was shown to be highly conserved [28,29,30,31]. In addition, PiuA and PirA, and also TonB-dependent receptors, were shown to mediate the uptake of siderophore–iron complexes [32]. These receptors have been associated with the cellular entry of CFDC in Gram-negative pathogens [25,33,34]. CFDC′s primary targets are cell wall synthesizing proteins associated with β-lactam activity, such as the penicillin-binding proteins 1 and 3 (PBP1 and PBP3) [35]. Randomized clinical trials, and other small case series studies, showed CFDC as a promising alternative to treat carbapenemase-producing pathogens and other less frequent non-fermenters, such as Stenotrophomonas maltophilia, Burkholderia spp., and Achromobacter spp [7,22,36,37,38,39,40,41].

Simner et al. explored possible resistance mechanisms to CFDC in 14 isolates of carbapenem-resistant Enterobacterales that exhibited baseline CFDC resistance (minimum inhibitory concentration (MICs) >/= 4 mg/L) [42]. They identified heterogeneous mechanisms that include the combination of β-lactamase production and permeability defects contributing to elevated CFDC MIC. Particularly, some of the mechanisms identified were the presence of New Delhi metallo-β-lactamase (NDM) carbapenemases, the occurrence of outer membrane porin mutations, and the presence of efflux transporters among the isolates evaluated. In addition, mutations in the baeS gene, responsible for encoding a sensor kinase protein of the two-component BaeSR and mutations in tonB3, exbD, envZ, or ompR, were identified among the clinical isolates that exhibited elevated CFDC MICs. The down-regulation of specific iron transport receptors in Pseudomonas aeruginosa, named FecIRA, is correlated with resistance to CFDC [43]. Similarly, in A. baumannii, CFDC resistance was associated with the reduced expression of the TonB-dependent receptor gene pirA as well as mutations in the penicillin-binding proteins 3 (PBP3). The presence of acquired β-lactamases, such as PER, may have also contributed to resistance in some strains [44,45]. So far, studies have not linked β-lactamase activity, nor levels of expression of PBPs, to CFDC resistance.

A. baumannii senses components of human fluids and responds by modifying its transcriptional and phenotypic profiles [46,47,48,49,50]. Human serum albumin (HSA), as well as human pleural fluid (HPF), modulates the expression of genes associated with iron uptake systems, biofilm formation, antibiotic resistance, and DNA acquisition, among others [47,51,52]. In previous studies, we observed that CRAB AB5075 genes associated with iron uptake systems were down-regulated when exposed to HPF and 0.2% HSA [47], while genes associated with β-lactam resistance were up-regulated in the presence of physiological concentrations of HSA and human serum (HS) [51,52]. Understanding the modification in the expression of iron uptake systems and β-lactam resistance genes in A. baumannii exposed to biological fluids could allow future strategies to protect antibiotics from a possible deleterious in vivo efficacy. In this work, we describe the effect of HS, HSA, and HPF on representative CRAB strains with different genetic backgrounds, focusing our analysis on the level of expression of iron uptake TonB-dependent receptors and β-lactam resistance genes.

2. Materials and Methods

2.1. Bacterial Strains

The model multidrug-resistant A. baumannii strain AB5075 was used [47,52,53]. In addition, A. baumannii AMA16 and AB0057 strains were also used [54,55,56,57]. The AB5075 strain contains the carbapenem resistance genes blaOXA-23, blaGES-14, and blaADC. The AMA16 strain presents blaNDM-1, blaPER-7, and ISAba125 resistance genes. The AB0057 strain harbors the genes blaTEM-1, blaOXA-23, and blaADC. This strain was isolated in the Walter Reed Army Medical Center, Bethesda, MD 20814, USA [58]. In addition, all the strains presented conserved resistance genes such as blaOXA-51-like, carO, pbp1, and pbp3. Nineteen additional CRAB strains, belonging to different clonal complexes, were included to performed CFDC susceptibility assays [54,55].

2.2. RNA Extraction and Quantitative Reverse Transcription Polymerase Chain Reaction (qRT-PCR)

Overnight cultures of A. baumannii strains were diluted 1:10 in fresh LB medium, LB medium containing 3.5% HSA (physiological concentration), containing 4% HPF, or 100% pooled normal HS, and incubated with agitation for 5 h at 37 °C. Pure HSA (Sigma-Aldrich, St. Louis, MO, USA) and pooled normal human serum from a certified vendor (Innovative Research Inc, Novi, MI, USA) were used in the cultures. RNA was extracted from each strain using the Direct-zol RNA Kit (Zymo Research, Irvine, CA, USA), following the manufacturer’s instructions. Total RNA extractions were performed in three biological replicates for each condition. The integrity of the RNA samples was verified by agarose gel electrophoresis. The extracted and DNase-treated RNA was used to synthesize cDNA using the manufacturer’s protocol provided within the iScriptTM Reverse Transcription Supermix for qPCR (Bio-Rad, Hercules, CA, USA). The cDNA concentrations were adjusted to 50 ng/µL and qPCR was conducted using the qPCRBIO SyGreen Blue Mix Lo-ROX, following the manufacturer’s protocol (PCR Biosystems, Wayne, PA, USA). At least three biological replicates of cDNA were used in triplets and were run using the CFX96 TouchTM Real-Time PCR Detection System (Bio-Rad, Hercules, CA, USA). Transcriptional levels of each sample were normalized to the transcriptional level of rpoB. The relative quantification of gene expression was performed using the comparative threshold method 2−ΔΔCt. The ratios obtained after normalization were expressed as folds of change compared with cDNA samples isolated from the bacterial cultures in the LB. Asterisks indicate significant differences as determined by ANOVA, followed by Tukey’s multiple comparison test (p < 0.05), using GraphPad Prism (GraphPad software, San Diego, CA, USA).

2.3. Antimicrobial Susceptibility Testing

Antibiotic susceptibility assays were performed following the procedures recommended by the Clinical and Laboratory Standards Institute (CLSI), Malvern, PA, USA [59]. After OD adjustment, 100 µL of cells grown in fresh LB medium, LB medium containing 3.5% HSA, 4% HPF, or 100% HS were inoculated on Mueller–Hinton agar plates, as previously described [47,48,50]. Antimicrobial commercial E-strips (Liofilchem S.r.l., 64026 Roseto degli Abruzzi, Italy) for CFDC was used. Mueller–Hinton agar plates were incubated at 37 °C for 18 h. CLSI breakpoints were used for interpretation [60].

3. Results

3.1. Changes in the Expression Levels of Genes Associated with Iron Uptake Systems in the Presence of Human Fluids

Building upon on our previous observations on the AB5075 strain, we decided to further study the role of HS, HSA, and HPF on CRAB AB0057 and AMA16 strains. The selected strains belong to different clonal complexes and harbor clinically important β-lactamases, such as oxacillinases (OXA-23) and NDM-1, respectively [54,61], which are the most prevalent carbapenemases in A. baumannii and Enterobacterales, respectively [4,62,63]. Quantitative RT-PCR (qRT-PCR) assays, to evaluate the expression of the iron uptake TonB-dependent receptor pirA, piuA, and bauA, were carried out using total RNA extracted from cells cultured in lysogeny broth (LB), LB supplemented with 4% HPF and 3.5% HSA, and cells cultured in 100% HS, as previously described [47]. In addition, the analysis of the expression levels of other iron uptake-associated genes, such as tonB3, basE, feoA, fhuE1, and fhuE2, involved in transport and biosynthesis [64,65,66,67,68], was also performed.

In the CRAB AMA16, the expression of the iron transport-related genes bauA, pirA, and piuA was reduced in all tested conditions evaluated (Figure 1A and Table S1). Similar results were observed for the CRAB AB0057 strain. A reduction in the expression of bauA, pirA, and piuA in the tested condition was also seen (Figure 1B and Table S1). In addition, when the hypervirulent A. baumannii AB5075 strain was exposed to 3.5% HSA and the HS, the expression levels of the genes encoding for the above-mentioned TonB-receptor genes were down-regulated (Figure 1C and Table S1). Pimentel et al. previously showed that the levels of expression of AB5075 iron-related genes were down-regulated in cells cultured in iron-rich media [47]; this finding is in agreement with the level of expression of basE reported in this work (Figure S1B).

Figure 1.

Figure 1

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Genetic analysis of iron uptake genes of AMA16 (A), AB0057 (B), and AB5075 (C) A. baumannii strains and qRT-PCR of genes associated with iron uptake, pirA, piuA, and bauA, expressed in LB, LB supplemented with HPF or with HSA, or cultured in HS. Fold changes were calculated using double ΔCt analysis. At least three independent samples were used, and four technical replicates were performed from each sample. The LB was used as reference. Statistical significance (p < 0.05) was determined by ANOVA followed by Tukey’s multiple comparison test: one asterisk: p < 0.05; two asterisks: p < 0.01; and three asterisks: p < 0.001.

Analysis of available RNA-seq data of AB5075 cultivated in LB vs. 3.5% HSA showed that fhuE1, fhuE2, pirA, and piuA genes [47,68] were also down-regulated in the presence of HPF (Figure S1A). Moreover, the transcriptional levels of fhuE1, fhuE2, tonB, and feoA genes were further analyzed by qRT-PCR for the three strains (AMA16, AB0057, and AB5075) in the three tested conditions (HPF, HSA, and HS), showing a decrease in the level of expression in all of the strains in all of the tested conditions (Figure S1B), with the exception of an increase in the expression of feoA for AMA16 exposed to HPF (Figure S1).

3.2. Modulation of the Expression of β-Lactam Resistance Genes by Human Fluids

We previously observed that genes associated with β-lactam resistance, such as blaOXA-51-like, blaOXA-23, pbp1, and pbp3, were up-regulated in A. baumannii AB5075, AMA16, and AB0057 when cultured in the presence of 3.5% HSA (51, 52). To further examine if changes in genes associated with β-lactam resistance were affected by HS or HPF in the CRAB strains, qRT-PCR was used to assess the gene expression of blaOXA-51-like, blaOXA-23, blaNDM-1, pbp1, pbp3, and carO in cultures of the strains AMA16 and AB0057 containing HS or HPF.

This transcriptional analysis revealed a down-regulation, with a log2 fold change of -2.84 and −1.62, in expression levels of blaNDM-1 in A. baumannii AMA16 cultured in the presence of HS or HPF, respectively (Figure 2A and Table S1). In this strain, the levels of expression of ISAba125, blaPER-7, pbp1, and pbp3 were up-regulated in the presence of HPF (Table S1). HS also induced the up-regulation of ISAba125 (Figure 2A). In the case of the AB0057 strain, we observed an increase in the expression of blaOXA-23, blaOXA-51, carO, blaADC, pbp1, and pbp3 in cultures containing HPF. In cultures containing HS, the former four genes were up-regulated (Figure 2B and Table S1). Assessment of the changes in β-lactam resistance-associated A. baumannii AB5075 genes in the presence of HPF showed the down-regulation of the carO and blaGES-14 genes (Figure 2C). The carO gene encodes for an outer membrane protein channel that allows the permeation of imipenem in A. baumannii [69]. The marked down-regulation of carO (more than 4 Log2 fold change, Table S1) could be contributing to limited CDFC entrance; however, further analysis is needed to establish this. On the other hand, the expression levels of blaOXA-51, pbp1, pbp3, and blaADC were increased (Figure 2C).

Figure 2.

Figure 2

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(A–C) Genetic analysis of β-lactamase and PBP genes of AMA16 (A), AB0057 (B), and AB5075 (C) A. baumannii strains and qRT-PCR of genes associated with β-lactams resistance expressed in LB, LB supplemented with HPF, or in HS. Fold changes were calculated using double ΔCt analysis. At least three independent samples were used. LB was used as the reference condition. Statistical significance (p < 0.05) was determined by ANOVA followed by Tukey’s multiple comparison test: one asterisk: p < 0.05; two asterisks: p < 0.01; and three asterisks: p < 0.001. (D) Effect of HSA and HPF on the antimicrobial susceptibility of A. baumannii representative strains AMA40 and AMA113 grown in LB broth, LB broth plus 3.5% HSA, or HPF, that were used to perform cefiderocol (CFDC) susceptibility. Minimum inhibitory concentration (MIC) on cation-adjusted Mueller–Hinton agar was performed by MTS (Liofilchem S.r.l., 64026 Roseto degli Abruzzi TE, Italy), following the manufacturer’s recommendations.

The impact of human fluids in CFDC activity was further studied using a panel of twenty CRAB strains, including AB5075, AMA16, and AB0057. Cells cultured in LB, LB supplemented with HPF or 3.5% HSA, were used to determine the MICs of CFDC. Ten strains had baseline resistance to CFDC (Table S1).

An increase in the MIC values was observed in 14 strains when the cells were growing in the presence of HSA or HPF (Table 1 and Figure 2D). We draw attention to the occurrence of heteroresistant colonies, with the inhibition ellipse, in 11 of the tested strains (Table 1 and Figure S2). Most of the strains that exhibited this phenomenon harbored blaPER-7 [54]. Our results agree with a recent report indicating that PER-like β-lactamases contribute to a decreased susceptibility to CFDC in A. baumannii [45]. In addition, they observed that the combination of CFDC with avibactam may inhibit the activity of PER-type ß-lactamases [45].

Table 1.

Minimal inhibitory concentrations of cefiderocol (CFDC) for 22 carbapenem-resistant Acinetobacter baumannii representative strains performed using CFDC MTS strips (Liofilchem S.r.l., 64026 Roseto degli Abruzzi TE, Italy) on Mueller–Hinton agar (cation adjusted). A. baumannii cells were cultured in LB or LB supplemented with 3.5% HSA or HPF, respectively.

CFDC MICs (mg/L)
Strain LB HPF 3.5% HSA
AB5075 0.5 (S) 1 (S) 2 (S)
ABUH702 0.38 (S) 1.5 (S) 3 (S)
AMA16 >4.5 * (I) >256 (R) 32 * (R)
AB0057 1 (S) 8 (I) 1.5 (S)
AMA40 0.5 (S) 16 * (R) 3 (S)
AMA41 0.094 (S) 0.5–0.75 (S) 2 (S)
AMA113 0.5 (S) 1.5 (S) 1.5 (S)
AMA181 0.19 (S) 0.19 (S) 0.75 (S)
AMA3 24 (R) >256 (R) 32 * (R)
AMA4 16 * (R) 48 * (R) 64 * (R)
AMA5 >256 (R) >256 (R) 16 * (R)
AMA9 32 (R) 48 (R) 16 (R)
AMA14 8 * (I) 16 * (R) 12 (I)
AMA17 >256 (R) >256 (R) >256 (R)
AMA18 64 * (R) 16 * (R) 16 * (R)
AMA19 4 (S) 4 (S) 48 * (R)
AMA28 32 * (R) >256 (R) 32 * (R)
AMA30 64 * (R) 128 * (R) 12 * (I)
AMA31 >256 (R) >256 (R) 96 * (R)
AMA33 16 * (R) >256 (R) >256 (R)
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* Intra-colonies are present. S: Susceptible, I: Intermediate, R: Resistant.

4. Discussion

Immediately after the invasion of infecting bacteria, the body responds by reducing free iron levels in the blood and tissues (hypoferremic response) [70,71,72]. In the face of these nutritional limitations, microorganisms evolve strategies to scavenge sufficient trace elements necessary to support their metabolism and growth. Among them, siderophore-mediated iron uptake systems are widespread among bacterial pathogens and are the systems utilized by CFDC to increase cell entrance.

Previous reports support a link between mutations in iron transporters and a decrease in susceptibility to CFDC [33,42,44]. In particular, PirA and PiuA have been linked with CFDC entry and CFDC resistance when mutations in these genes have been reported [33,34]. Our results show a decrease in the expression of genes coding for the TonB-dependent receptors BauA, PirA, and PiuA, when CRAB strains are exposed to human fluids and HSA. In addition, the increased expression of β-lactam resistance-associated genes, in particular, the increased expression of genes encoding PBPs in the three tested conditions, was also observed. These two observations are coupled with elevated CFDC MICs in 14 CRAB isolates when exposed to HPF and/or HSA.

Supporting our observations, recent studies have shown that the down-regulation of pirA and piuA in three A. baumannii clinical strains is associated with resistance to CFDC [33,44]. In addition, this work showed that the alteration of the hydrophobic isoleucine to the charged asparagine, at position 236 of PBP3, could also contribute to the CFDC resistance [44].

In other Gram-negatives, the relationship between mutations in TonB-dependent catecholate siderophore receptors and CFDC was observed. A recent case report showed the development of resistance to CFDC in a patient with intra-abdominal and bloodstream infections caused by a CR-Enterobacter cloacae strain after 21 days of CFDC treatment. Whole-genome sequencing revealed heterogeneous mutations in the cirA gene, which encodes a TonB-dependent catecholate siderophore receptor, conferring phenotypic resistance to cefiderocol. cirA was the only catecholate receptor present in that clinical isolate, supporting the role of the mutation of this gene in CFDC resistance [73]. Moreover, in Pseudomonas aeruginosa, mutations in piuD and pirR, major iron transport pathways, and a leucine-to-phenylalanine substitution at amino acid position 147 in the ADC β-lactamase, were associated with CFDC MIC increases [73,74]. Simner et al. reported that substitutions in the region of the AmpC omega loop contribute to increased cefiderocol MICs to P. aeruginosa [75].

The present work focuses on the effects of different human bodily fluids on iron uptake and antibiotic resistance genes, some of which were linked with the reduced susceptibility to CFDC. Our results show a down-regulation or up-regulation of the genes associated with iron uptake or β-lactam resistance. These alterations were seen among the different strains and under different conditions. We believe that the sum of all the changes may contribute to the reduced effectiveness of CFDC when studied in vitro.

The exposure of A. baumannii to human fluids results in the transcriptional repression of genes coding for proteins involved in TonB-dependent siderophore-mediated iron acquisition. Taking into account these observations and the fact that HPF and HS possess a high concentration of HSA, a protein that has been reported as an important host iron reservoir [76], it is possible to speculate that the reduced efficacy of CFDC in the presence of these fluids is a consequence of the iron-rich environment created by the presence of HSA. In the case of HPF, we cannot discount the possibility that other proteins such as ferritin, which are abundant in HPF, may provide the necessary metal ions through this source, reducing the expression of the catechol iron uptake system and the number of entry sites for cefiderocol, leading to diminished efficacy.

5. Conclusions

Overall, our results show that A. baumannii may be unique in its response to human bodily fluids by modulating the expression of iron uptake genes and β-lactam resistance-associated determinants. We hypothesize that the presence of iron-binding proteins in the human fluids is sensed by A. baumannii, which in turn responds by down-regulating the expression of iron uptake system genes, impacting CDFC activity. The particular changes in expression of the aforementioned group of genes, which is not evaluated in traditional susceptibility tests, may contribute to increases in MICs. These results also raise questions regarding the expression of other factors that may contribute to challenges in overcoming infections by A. baumannii.

The limitations inherent in performing MICs in the presence of bodily fluids (protein binding) are recognized. We are also aware that comparing these analyses does not take into account the pharmacokinetic and pharmacodynamic (PK/PD) parameters that ensure drug efficacy [36,77]. Lastly, we appreciate that these data must also be evaluated in the context of outcomes in animal models of infection [78,79,80]. Nevertheless, the impact on iron transport mechanisms uncovered in these observations merits further analyses.

Acknowledgments

We are grateful to Michael R. Jacobs for his critical reading of the manuscript.

Supplementary Materials

The following supporting information can be downloaded at https://www.mdpi.com/article/10.3390/biomedicines10030600/s1. Table S1. Comparison of the level of expression of iron associated and β-lactam resistance genes obtained by qRT-PCR in the three CRAB strains. Figure S1. (A) Heatmap outlining the differential expression of genes, fhuE1, fhuE2, pirA and piuA associated with iron uptake in presence of 4% HPF or 0.2% HSA. The asterisks represent the DEGs (adjusted p-value < 0.05 with. log2fold change >1). (B) Differential expression of genes associated with iron-uptake obtained for A. baumannii AMA16, AB0057 and AB5075 strains cultured in the presence of HPF, HSA or HS. Figure S2. AMA40 CFDC MICs displaying colonies within the E-test zone and the MICs results of the selected intra colonies (IHC1 and IHC2). CFDC MICs were performed following the CLSI guidelines using CAMHA. The intracolonies obtained when AMA40 was exposed to 4% HPF were subculture and the CFDC MIC was performed.

Click here for additional data file. (322.8KB, zip)

Author Contributions

C.P., C.L., F.P., M.R.T., T.S., R.A.B. and M.S.R. conceived the study and designed the experiments. C.P., C.L., F.P., M.R.T., T.S., J.E., B.N., S.A., A.C. (Aimee Carranza), V.M., A.J.V., A.C. (Alejandra Corso), L.A.A., M.E.T., R.A.B. and M.S.R. performed the experiments and genomics and bioinformatics analyses. C.P., C.L., F.P., M.R.T., T.S., A.J.V., L.A.A., R.A.B., M.E.T. and M.S.R. analyzed the data and interpreted the results. R.A.B., M.E.T. and M.S.R. contributed reagents/materials/analysis tools. F.P., M.R.T., T.S., L.A.A., R.A.B., M.E.T. and M.S.R. wrote and revised the manuscript. All authors have read and agreed to the published version of the manuscript.

Funding

The authors’ work was supported by NIH SC3GM125556 to M.S.R., R01AI100560, R01AI063517, R01AI072219 to R.A.B. and 2R15 AI047115 to M.E.T. This study was supported in part by funds and/or facilities provided by the Cleveland Department of Veterans Affairs, award number 1I01BX001974, to R.A.B. from the Biomedical Laboratory Research and Development Service of the VA Office of Research and Development, and the Geriatric Research Education and Clinical Center VISN 10 to R.A.B., C.P. and J.E. were supported by grant MHRT 2T37MD001368 from the National Institute on Minority Health and Health Disparities, National Institute of Health. S.A. and A.C. (Aimee Carranza) were supported by Project RAISE, U.S. Department of Education HSI-STEM, award number P031C160152. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health or the Department of Veterans Affairs. M.R.T. and T.S. are recipients of a postdoctoral fellowship from CONICET. A.J.V. is a staff member from CONICET.

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

All data pertaining to the study described in the manuscript is described in the report.

Conflicts of Interest

The authors declare no conflict of interest.

Footnotes

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.

References

  • 1.Eichenberger E.M., Thaden J.T. Epidemiology and Mechanisms of Resistance of Extensively Drug Resistant Gram-Negative Bacteria. Antibiotics. 2019;8:37. doi: 10.3390/antibiotics8020037. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 2.Holmes C.L., Anderson M.T., Mobley H.L.T., Bachman M.A. Pathogenesis of Gram-negative bacteremia. Clin. Microbiol. Rev. 2021;34:e00234-e20. doi: 10.1128/CMR.00234-20. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 3.Garcia-Ortega L., Arch O., Perez-Canosa C., Lupion C., Gonzalez C., Rodriguez-Bano J., Spanish Study Group of Nosocomial Infections Control measures for Acinetobacter baumannii: A survey of Spanish hospitals. Enferm. Infecc. Microbiol. Clín. 2011;29:36–38. doi: 10.1016/j.eimc.2010.04.012. [DOI] [PubMed] [Google Scholar]
  • 4.Ramirez M.S., Bonomo R.A., Tolmasky M.E. Carbapenemases: Transforming Acinetobacter baumannii into a Yet More Dangerous Menace. Biomolecules. 2020;10:720. doi: 10.3390/biom10050720. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 5.CDC . Antibiotic Resistance Threats in the United States. US Department of Health and Human Services, CDC; Atlanta, GA, USA: 2019. [Google Scholar]
  • 6.Karaiskos I., Lagou S., Pontikis K., Rapti V., Poulakou G. The “Old” and the “New” Antibiotics for MDR Gram-Negative Pathogens: For Whom, When, and How. Front. Public Health. 2019;7:151. doi: 10.3389/fpubh.2019.00151. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 7.Bassetti M., Echols R., Matsunaga Y., Ariyasu M., Doi Y., Ferrer R., Lodise T.P., Naas T., Niki Y., Paterson D.L., et al. Efficacy and safety of cefiderocol or best available therapy for the treatment of serious infections caused by carbapenem-resistant Gram-negative bacteria (CREDIBLE-CR): A randomised, open-label, multicentre, pathogen-focused, descriptive, phase 3 trial. Lancet Infect. Dis. 2021;21:226–240. doi: 10.1016/S1473-3099(20)30796-9. [DOI] [PubMed] [Google Scholar]
  • 8.Bassetti M., Peghin M., Vena A., Giacobbe D.R. Treatment of Infections Due to MDR Gram-Negative Bacteria. Front. Med. 2019;6:74. doi: 10.3389/fmed.2019.00074. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 9.Isler B., Doi Y., Bonomo R.A., Paterson D.L. New treatment options against carbapenem-resistant Acinetobacter baumannii infections. Antimicrob. Agents Chemother. 2019;63:e01110-e18. doi: 10.1128/AAC.01110-18. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 10.Bonomo R.A., Burd E.M., Conly J., Limbago B.M., Poirel L., Segre J.A., Westblade L.F. Carbapenemase-Producing Organisms: A Global Scourge. Clin. Infect. Dis. 2018;66:1290–1297. doi: 10.1093/cid/cix893. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 11.Spellberg B., Bonomo R.A. The deadly impact of extreme drug resistance in Acinetobacter baumannii. Crit. Care Med. 2014;42:1289–1291. doi: 10.1097/CCM.0000000000000181. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 12.Paterson D.L., Isler B., Stewart A. New treatment options for multiresistant gram negatives. Curr. Opin. Infect. Dis. 2020;33:214–223. doi: 10.1097/QCO.0000000000000627. [DOI] [PubMed] [Google Scholar]
  • 13.McLeod S.M., Moussa S.H., Hackel M.A., Miller A.A. In Vitro Activity of Sulbactam-Durlobactam against Acinetobacter baumannii-calcoaceticus Complex Isolates Collected Globally in 2016 and 2017. Antimicrob. Agents Chemother. 2020;64:e02534-e19. doi: 10.1128/AAC.02534-19. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 14.Lomovskaya O., Nelson K., Rubio-Aparicio D., Tsivkovski R., Sun D., Dudley M.N. The Impact of Intrinsic Resistance Mechanisms on Potency of QPX7728, a New Ultra-Broad-Spectrum Beta-lactamase Inhibitor of Serine and Metallo Beta-Lactamases in Enterobacteriaceae, Pseudomonas aeruginosa, and Acinetobacter baumannii. Antimicrob. Agents Chemother. 2020;65:e00552-e20. doi: 10.1128/AAC.00552-20. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 15.Karaiskos I., Galani I., Souli M., Giamarellou H. Novel beta-lactam-beta-lactamase inhibitor combinations: Expectations for the treatment of carbapenem-resistant Gram-negative pathogens. Expert Opin. Drug Metab. Toxicol. 2019;15:133–149. doi: 10.1080/17425255.2019.1563071. [DOI] [PubMed] [Google Scholar]
  • 16.Barnes M.D., Kumar V., Bethel C.R., Moussa S.H., O’Donnell J., Rutter J.D., Good C.E., Hujer K.M., Hujer A.M., Marshall S.H., et al. Targeting Multidrug-Resistant Acinetobacter spp.: Sulbactam and the Diazabicyclooctenone beta-Lactamase Inhibitor ETX2514 as a Novel Therapeutic Agent. mBio. 2019;10:e00159-e19. doi: 10.1128/mBio.00159-19. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 17.Zhanel G.G., Lawrence C.K., Adam H., Schweizer F., Zelenitsky S., Zhanel M., Lagace-Wiens P.R.S., Walkty A., Denisuik A., Golden A., et al. Imipenem-Relebactam and Meropenem-Vaborbactam: Two Novel Carbapenem-beta-Lactamase Inhibitor Combinations. Drugs. 2018;78:65–98. doi: 10.1007/s40265-017-0851-9. [DOI] [PubMed] [Google Scholar]
  • 18.Wright H., Bonomo R.A., Paterson D.L. New agents for the treatment of infections with Gram-negative bacteria: Restoring the miracle or false dawn? Clin. Microbiol. Infect. 2017;23:704–712. doi: 10.1016/j.cmi.2017.09.001. [DOI] [PubMed] [Google Scholar]
  • 19.Durand-Reville T.F., Guler S., Comita-Prevoir J., Chen B., Bifulco N., Huynh H., Lahiri S., Shapiro A.B., McLeod S.M., Carter N.M., et al. ETX2514 is a broad-spectrum beta-lactamase inhibitor for the treatment of drug-resistant Gram-negative bacteria including Acinetobacter baumannii. Nat. Microbiol. 2017;2:17104. doi: 10.1038/nmicrobiol.2017.104. [DOI] [PubMed] [Google Scholar]
  • 20.Lee Y.R., Yeo S. Cefiderocol, a New Siderophore Cephalosporin for the Treatment of Complicated Urinary Tract Infections Caused by Multidrug-Resistant Pathogens: Preclinical and Clinical Pharmacokinetics, Pharmacodynamics, Efficacy and Safety. Clin. Drug Investig. 2020;40:901–913. doi: 10.1007/s40261-020-00955-x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 21.Parsels K.A., Mastro K.A., Steele J.M., Thomas S.J., Kufel W.D. Cefiderocol: A novel siderophore cephalosporin for multidrug-resistant Gram-negative bacterial infections. J. Antimicrob. Chemother. 2021;76:1379–1391. doi: 10.1093/jac/dkab015. [DOI] [PubMed] [Google Scholar]
  • 22.Bonomo R.A. Cefiderocol: A Novel Siderophore Cephalosporin Defeating Carbapenem-resistant Pathogens. Clin. Infect. Dis. 2019;69:S519–S520. doi: 10.1093/cid/ciz823. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 23.Zhanel G.G., Golden A.R., Zelenitsky S., Wiebe K., Lawrence C.K., Adam H.J., Idowu T., Domalaon R., Schweizer F., Zhanel M.A., et al. Cefiderocol: A Siderophore Cephalosporin with Activity Against Carbapenem-Resistant and Multidrug-Resistant Gram-Negative Bacilli. Drugs. 2019;79:271–289. doi: 10.1007/s40265-019-1055-2. [DOI] [PubMed] [Google Scholar]
  • 24.Aoki T., Yoshizawa H., Yamawaki K., Yokoo K., Sato J., Hisakawa S., Hasegawa Y., Kusano H., Sano M., Sugimoto H., et al. Cefiderocol (S-649266), A new siderophore cephalosporin exhibiting potent activities against Pseudomonas aeruginosa and other gram-negative pathogens including multi-drug resistant bacteria: Structure activity relationship. Eur. J. Med. Chem. 2018;155:847–868. doi: 10.1016/j.ejmech.2018.06.014. [DOI] [PubMed] [Google Scholar]
  • 25.Ito A., Nishikawa T., Matsumoto S., Yoshizawa H., Sato T., Nakamura R., Tsuji M., Yamano Y. Siderophore Cephalosporin Cefiderocol Utilizes Ferric Iron Transporter Systems for Antibacterial Activity against Pseudomonas aeruginosa. Antimicrob. Agents Chemother. 2016;60:7396–7401. doi: 10.1128/AAC.01405-16. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 26.Sheldon J.R., Skaar E.P. Acinetobacter baumannii can use multiple siderophores for iron acquisition, but only acinetobactin is required for virulence. PLoS Pathog. 2020;16:e1008995. doi: 10.1371/journal.ppat.1008995. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 27.Antunes L.C., Imperi F., Towner K.J., Visca P. Genome-assisted identification of putative iron-utilization genes in Acinetobacter baumannii and their distribution among a genotypically diverse collection of clinical isolates. Res. Microbiol. 2011;162:279–284. doi: 10.1016/j.resmic.2010.10.010. [DOI] [PubMed] [Google Scholar]
  • 28.Nwugo C.C., Arivett B.A., Zimbler D.L., Gaddy J.A., Richards A.M., Actis L.A. Effect of ethanol on differential protein production and expression of potential virulence functions in the opportunistic pathogen Acinetobacter baumannii. PLoS ONE. 2012;7:e51936. doi: 10.1371/journal.pone.0051936. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 29.Zimbler D.L., Penwell W.F., Gaddy J.A., Menke S.M., Tomaras A.P., Connerly P.L., Actis L.A. Iron acquisition functions expressed by the human pathogen Acinetobacter baumannii. Biometals. 2009;22:23–32. doi: 10.1007/s10534-008-9202-3. [DOI] [PubMed] [Google Scholar]
  • 30.Ramirez M.S., Penwell W.F., Traglia G.M., Zimbler D.L., Gaddy J.A., Nikolaidis N., Arivett B.A., Adams M.D., Bonomo R.A., Actis L.A., et al. Identification of potential virulence factors in the model strain Acinetobacter baumannii A118. Front. Microbiol. 2019;10:1599. doi: 10.3389/fmicb.2019.01599. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 31.Moynié L., Serra I., Scorciapino M.A., Oueis E., Page M.G., Ceccarelli M., Naismith J.H. Preacinetobactin not acinetobactin is essential for iron uptake by the BauA transporter of the pathogen. eLife. 2018;7:e42270. doi: 10.7554/eLife.42270. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 32.Ghysels B., Ochsner U., Möllman U., Heinisch L., Vasil M., Cornelis P., Matthijs S. The Pseudomonas aeruginosa pirA gene encodes a second receptor for ferrienterobactin and synthetic catecholate analogues. FEMS Microbiol. Lett. 2005;246:167–174. doi: 10.1016/j.femsle.2005.04.010. [DOI] [PubMed] [Google Scholar]
  • 33.Moynie L., Luscher A., Rolo D., Pletzer D., Tortajada A., Weingart H., Braun Y., Page M.G., Naismith J.H., Kohler T. Structure and Function of the PiuA and PirA Siderophore-Drug Receptors from Pseudomonas aeruginosa and Acinetobacter baumannii. Antimicrob. Agents Chemother. 2017;61:e02531-e16. doi: 10.1128/AAC.02531-16. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 34.Luscher A., Moynié L., Auguste P.S., Bumann D., Mazza L., Pletzer D., Naismith J.H., Köhler T. TonB-Dependent Receptor Repertoire of Pseudomonas aeruginosa for Uptake of Siderophore-Drug Conjugates. Antimicrob. Agents Chemother. 2018;62:e00097-e18. doi: 10.1128/AAC.00097-18. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 35.Sato T., Yamawaki K. Cefiderocol: Discovery, Chemistry, and In Vivo Profiles of a Novel Siderophore Cephalosporin. Clin. Infect. Dis. 2019;69:S538–S543. doi: 10.1093/cid/ciz826. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 36.McCreary E.K., Heil E.L., Tamma P.D. New Perspectives on Antimicrobial Agents: Cefiderocol. Antimicrob. Agents Chemother. 2021;65:e02171-e20. doi: 10.1128/AAC.02171-20. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 37.Wunderink R.G., Matsunaga Y., Ariyasu M., Clevenbergh P., Echols R., Kaye K.S., Kollef M., Menon A., Pogue J.M., Shorr A.F., et al. Cefiderocol versus high-dose, extended-infusion meropenem for the treatment of Gram-negative nosocomial pneumonia (APEKS-NP): A randomised, double-blind, phase 3, non-inferiority trial. Lancet Infect. Dis. 2021;21:213–225. doi: 10.1016/S1473-3099(20)30731-3. [DOI] [PubMed] [Google Scholar]
  • 38.Jean S.S., Gould I.M., Lee W.S., Hsueh P.R., International Society of Antimicrobial Chemotherapy New Drugs for Multidrug-Resistant Gram-Negative Organisms: Time for Stewardship. Drugs. 2019;79:705–714. doi: 10.1007/s40265-019-01112-1. [DOI] [PubMed] [Google Scholar]
  • 39.Jacobs M.R., Abdelhamed A.M., Good C.E., Rhoads D.D., Hujer K.M., Hujer A.M., Domitrovic T.N., Rudin S.D., Richter S.S., van Duin D., et al. ARGONAUT-I: Activity of Cefiderocol (S-649266), a Siderophore Cephalosporin, against Gram-Negative Bacteria, Including Carbapenem-Resistant Nonfermenters and Enterobacteriaceae with Defined Extended-Spectrum beta-Lactamases and Carbapenemases. Antimicrob. Agents Chemother. 2019;63:e01801-e18. doi: 10.1128/AAC.01801-18. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 40.Bavaro D.F., Belati A., Diella L., Stufano M., Romanelli F., Scalone L., Stolfa S., Ronga L., Maurmo L., Dell’Aera M., et al. Cefiderocol-Based Combination Therapy for “Difficult-to-Treat” Gram-Negative Severe Infections: Real-Life Case Series and Future Perspectives. Antibiotics. 2021;10:652. doi: 10.3390/antibiotics10060652. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 41.Oliva A., Ceccarelli G., De Angelis M., Sacco F., Miele M.C., Mastroianni C.M., Venditti M. Cefiderocol for compassionate use in the treatment of complicated infections caused by extensively and pan-resistant Acinetobacter baumannii. J. Glob. Antimicrob. Resist. 2020;23:292–296. doi: 10.1016/j.jgar.2020.09.019. [DOI] [PubMed] [Google Scholar]
  • 42.Simner P.J., Beisken S., Bergman Y., Ante M., Posch A.E., Tamma P.D. Defining Baseline Mechanisms of Cefiderocol Resistance in the Enterobacterales. Microb. Drug Resist. 2022;28:161–170. doi: 10.1089/mdr.2021.0095. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 43.Van Delden C., Page M.G., Köhler T. Involvement of Fe uptake systems and AmpC β-lactamase in susceptibility to the siderophore monosulfactam BAL30072 in Pseudomonas aeruginosa. Antimicrob. Agents Chemother. 2013;57:2095–2102. doi: 10.1128/AAC.02474-12. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 44.Malik S., Kaminski M., Landman D., Quale J. Cefiderocol Resistance in Acinetobacter baumannii: Roles of β-Lactamases, Siderophore Receptors, and Penicillin Binding Protein 3. Antimicrob. Agents Chemother. 2020;64:e01221-20. doi: 10.1128/AAC.01221-20. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 45.Poirel L., Sadek M., Nordmann P. Contribution of PER-type and NDM-type ss-lactamases to cefiderocol resistance in Acinetobacter baumannii. Antimicrob. Agents Chemother. 2021;65:e00877-e21. doi: 10.1128/AAC.00877-21. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 46.Martinez J., Razo-Gutierrez C., Le C., Courville R., Pimentel C., Liu C., Fung S.E., Tuttobene M.R., Phan K., Vila A.J., et al. Cerebrospinal fluid (CSF) augments metabolism and virulence expression factors in Acinetobacter baumannii. Sci. Rep. 2021;11:4737. doi: 10.1038/s41598-021-81714-6. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 47.Pimentel C., Le C., Tuttobene M.R., Subils T., Martinez J., Sieira R., Papp-Wallace K.M., Keppetipola N., Bonomo R.A., Actis L.A., et al. Human Pleural Fluid and Human Serum Albumin Modulate the Behavior of a Hypervirulent and Multidrug-Resistant (MDR) Acinetobacter baumannii Representative Strain. Pathogens. 2021;10:471. doi: 10.3390/pathogens10040471. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 48.Martinez J., Fernandez J.S., Liu C., Hoard A., Mendoza A., Nakanouchi J., Rodman N., Courville R., Tuttobene M.R., Lopez C., et al. Human pleural fluid triggers global changes in the transcriptional landscape of Acinetobacter baumannii as an adaptive response to stress. Sci. Rep. 2019;9:17251. doi: 10.1038/s41598-019-53847-2. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 49.Rodman N., Martinez J., Fung S., Nakanouchi J., Myers A.L., Harris C.M., Dang E., Fernandez J.S., Liu C., Mendoza A.M., et al. Human Pleural Fluid Elicits Pyruvate and Phenylalanine Metabolism in Acinetobacter baumannii to Enhance Cytotoxicity and Immune Evasion. Front. Microbiol. 2019;10:1581. doi: 10.3389/fmicb.2019.01581. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 50.Quinn B., Rodman N., Jara E., Fernandez J.S., Martinez J., Traglia G.M., Montana S., Cantera V., Place K., Bonomo R.A., et al. Human serum albumin alters specific genes that can play a role in survival and persistence in Acinetobacter baumannii. Sci. Rep. 2018;8:14741. doi: 10.1038/s41598-018-33072-z. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 51.Le C., Pimentel C., Tuttobene M.R., Subils T., Nishimura B., Traglia G.M., Perez F., Papp-Wallace K.M., Bonomo R.A., Tolmasky M.E., et al. Interplay between meropenem and human serum albumin on expression of carbapenem resistance genes and natural competence in Acinetobacter baumannii. Antimicrob. Agents Chemother. 2021;65:e01019-e21. doi: 10.1128/AAC.01019-21. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 52.Pimentel C., Le C., Tuttobene M.R., Subils T., Papp-Wallace K.M., Bonomo R.A., Tolmasky M.E., Ramirez M.S. Interaction of Acinetobacter baumannii with Human Serum Albumin: Does the Host Determine the Outcome? Antibiotics. 2021;10:833. doi: 10.3390/antibiotics10070833. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 53.Jacobs A.C., Thompson M.G., Black C.C., Kessler J.L., Clark L.P., McQueary C.N., Gancz H.Y., Corey B.W., Moon J.K., Si Y., et al. AB5075, a Highly Virulent Isolate of Acinetobacter baumannii, as a Model Strain for the Evaluation of Pathogenesis and Antimicrobial Treatments. mBio. 2014;5:e01076-e14. doi: 10.1128/mBio.01076-14. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 54.Adams M.D., Pasteran F., Traglia G.M., Martinez J., Huang F., Liu C., Fernandez J.S., Lopez C., Gonzalez L.J., Albornoz E., et al. Distinct mechanisms of dissemination of NDM-1 metallo- beta-lactamase in Acinetobacter spp. in Argentina. Antimicrob. Agents Chemother. 2020;64:e00324-20. doi: 10.1128/AAC.00324-20. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 55.Rodgers D., Pasteran F., Calderon M., Jaber S., Traglia G.M., Albornoz E., Corso A., Vila A.J., Bonomo R.A., Adams M.D., et al. Characterisation of ST25 NDM-1-producing Acinetobacter spp. strains leading the increase in NDM-1 emergence in Argentina. J. Glob. Antimicrob. Resist. 2020;23:108–110. doi: 10.1016/j.jgar.2020.08.015. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 56.Hujer A.M., Higgins P.G., Rudin S.D., Buser G.L., Marshall S.H., Xanthopoulou K., Seifert H., Rojas L.J., Domitrovic T.N., Cassidy P.M., et al. Nosocomial outbreak of extensively drug-resistant Acinetobacter baumannii isolates containing blaOXA-237 carried on a plasmid. Antimicrob. Agents Chemother. 2017;61:e00797-e17. doi: 10.1128/AAC.00797-17. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 57.Adams M.D., Chan E.R., Molyneaux N.D., Bonomo R.A. Genomewide analysis of divergence of antibiotic resistance determinants in closely related isolates of Acinetobacter baumannii. Antimicrob. Agents Chemother. 2010;54:3569–3577. doi: 10.1128/AAC.00057-10. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 58.Hujer K.M., Hujer A.M., Hulten E.A., Bajaksouzian S., Adams J.M., Donskey C.J., Ecker D.J., Massire C., Eshoo M.W., Sampath R., et al. Analysis of antibiotic resistance genes in multidrug-resistant Acinetobacter sp. isolates from military and civilian patients treated at the Walter Reed Army Medical Center. Antimicrob. Agents Chemother. 2006;50:4114–4123. doi: 10.1128/AAC.00778-06. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 59.CLSI . Performance Standards for Antimicrobial Susceptibility Testing. 29th ed. Clinical Lab Standards Institute; Wayne, PA, USA: 2019. CLSI Document M100. [Google Scholar]
  • 60.CLSI . Performance Standards for Antimicrobial Susceptibility Testing. 30th ed. Clinical Lab Standards Institute; Wayne, PA, USA: 2020. CLSI Document M100. [Google Scholar]
  • 61.Adams M.D., Goglin K., Molyneaux N., Hujer K.M., Lavender H., Jamison J.J., MacDonald I.J., Martin K.M., Russo T., Campagnari A.A., et al. Comparative genome sequence analysis of multidrug-resistant Acinetobacter baumannii. J. Bacteriol. 2008;190:8053–8064. doi: 10.1128/JB.00834-08. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 62.Durante-Mangoni E., Andini R., Zampino R. Management of carbapenem-resistant Enterobacteriaceae infections. Clin. Microbiol. Infect. 2019;25:943–950. doi: 10.1016/j.cmi.2019.04.013. [DOI] [PubMed] [Google Scholar]
  • 63.Martinez-Martinez L. Carbapenemases: The never-ending story. Enferm. Infecc. Microbiol. Clin. 2019;37:73–75. doi: 10.1016/j.eimc.2018.12.006. [DOI] [PubMed] [Google Scholar]
  • 64.Moeck G.S., Coulton J.W. TonB-dependent iron acquisition: Mechanisms of siderophore-mediated active transport. Mol. Microbiol. 1998;28:675–681. doi: 10.1046/j.1365-2958.1998.00817.x. [DOI] [PubMed] [Google Scholar]
  • 65.Noinaj N., Guillier M., Barnard T.J., Buchanan S.K. TonB-dependent transporters: Regulation, structure, and function. Annu. Rev. Microbiol. 2010;64:43–60. doi: 10.1146/annurev.micro.112408.134247. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 66.Lau C.K., Krewulak K.D., Vogel H.J. Bacterial ferrous iron transport: The Feo system. FEMS Microbiol. Rev. 2016;40:273–298. doi: 10.1093/femsre/fuv049. [DOI] [PubMed] [Google Scholar]
  • 67.Mihara K., Tanabe T., Yamakawa Y., Funahashi T., Nakao H., Narimatsu S., Yamamoto S. Identification and transcriptional organization of a gene cluster involved in biosynthesis and transport of acinetobactin, a siderophore produced by Acinetobacter baumannii ATCC 19606T. Microbiology. 2004;150:2587–2597. doi: 10.1099/mic.0.27141-0. [DOI] [PubMed] [Google Scholar]
  • 68.Tiwari V., Rajeswari M.R., Tiwari M. Proteomic analysis of iron-regulated membrane proteins identify FhuE receptor as a target to inhibit siderophore-mediated iron acquisition in Acinetobacter baumannii. Int. J. Biol. Macromol. 2018;125:1156–1167. doi: 10.1016/j.ijbiomac.2018.12.173. [DOI] [PubMed] [Google Scholar]
  • 69.Mussi M.A., Limansky A.S., Relling V., Ravasi P., Arakaki A., Actis L.A., Viale A.M. Horizontal gene transfer and assortative recombination within the Acinetobacter baumannii clinical population provide genetic diversity at the single carO gene, encoding a major outer membrane protein channel. J. Bacteriol. 2011;193:4736–4748. doi: 10.1128/JB.01533-10. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 70.Baynes R.D., Bezwoda W.R. Lactoferrin and the inflammatory response. Adv. Exp. Med. Biol. 1994;357:133–141. doi: 10.1007/978-1-4615-2548-6_13. [DOI] [PubMed] [Google Scholar]
  • 71.Fillebeen C., Wilkinson N., Charlebois E., Katsarou A., Wagner J., Pantopoulos K. Hepcidin-mediated hypoferremic response to acute inflammation requires a threshold of Bmp6/Hjv/Smad signaling. Blood. 2018;132:1829–1841. doi: 10.1182/blood-2018-03-841197. [DOI] [PubMed] [Google Scholar]
  • 72.Caldwell M., Archibald F. The effect of the hypoferremic response on iron acquisition by and growth of murine lymphoma cells. Biochem. Cell Biol. 1987;65:651–657. doi: 10.1139/o87-086. [DOI] [PubMed] [Google Scholar]
  • 73.Klein S., Boutin S., Kocer K., Fiedler M.O., Störzinger D., Weigand M.A., Tan B., Richter D., Rupp C., Mieth M., et al. Rapid development of cefiderocol resistance in carbapenem-resistant Enterobacter cloacae during therapy is associated with heterogeneous mutations in the catecholate siderophore receptor cira. Clin. Infect Dis. 2021:ciab511. doi: 10.1093/cid/ciab511. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 74.Streling A.P., Al Obaidi M.M., Lainhart W.D., Zangeneh T., Khan A., Dinh A.Q., Hanson B., Arias C.A., Miller W.R. Evolution of Cefiderocol Non-Susceptibility in Pseudomonas aeruginosa in a Patient without Previous Exposure to the Antibiotic. Clin. Infect. Dis. 2021;73:e4472–e4474. doi: 10.1093/cid/ciaa1909. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 75.Simner P.J., Beisken S., Bergman Y., Posch A.E., Cosgrove S.E., Tamma P.D. Cefiderocol Activity against Clinical Pseudomonas aeruginosa Isolates Exhibiting Ceftolozane-Tazobactam Resistance. Open Forum Infect. Dis. 2021;8:ofab311. doi: 10.1093/ofid/ofab311. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 76.Pinsky M., Roy U., Moshe S., Weissman Z., Kornitzer D. Human Serum Albumin Facilitates Heme-Iron Utilization by Fungi. mBio. 2020;11:e00607-20. doi: 10.1128/mBio.00607-20. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 77.Konig C., Both A., Rohde H., Kluge S., Frey O.R., Rohr A.C., Wichmann D. Cefiderocol in Critically Ill Patients with Multi-Drug Resistant Pathogens: Real-Life Data on Pharmacokinetics and Microbiological Surveillance. Antibiotics. 2021;10:649. doi: 10.3390/antibiotics10060649. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 78.Kidd J.M., Abdelraouf K., Nicolau D.P. Development of Neutropenic Murine Models of Iron Overload and Depletion to Study the Efficacy of Siderophore-Antibiotic Conjugates. Antimicrob. Agents Chemother. 2019;64:e01961-e19. doi: 10.1128/AAC.01961-19. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 79.Kidd J.M., Abdelraouf K., Nicolau D.P. Efficacy of Humanized Cefiderocol Exposure Is Unaltered by Host Iron Overload in the Thigh Infection Model. Antimicrob. Agents Chemother. 2019;64:e01767-19. doi: 10.1128/AAC.01767-19. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 80.Matsumoto S., Singley C.M., Hoover J., Nakamura R., Echols R., Rittenhouse S., Tsuji M., Yamano Y. Efficacy of Cefiderocol against Carbapenem-Resistant Gram-Negative Bacilli in Immunocompetent-Rat Respiratory Tract Infection Models Recreating Human Plasma Pharmacokinetics. Antimicrob. Agents Chemother. 2017;61:e00700-17. doi: 10.1128/AAC.00700-17. [DOI] [PMC free article] [PubMed] [Google Scholar]

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Data Availability Statement

All data pertaining to the study described in the manuscript is described in the report.

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