Abstract
Background
This study aimed to explore the distribution and antimicrobial resistance of bloodstream infections (BSIs) pathogens at a large traditional Chinese medicine hospital in China.
Methods
Retrospective analysis of the pathogen distribution of BSIs and the changes in antimicrobial resistance during a 10-year period (2015–2024) was conducted in Longhua Hospital. Isolate identification was carried out by VITEK®2 Compact. Antimicrobial susceptibility testing was performed by minimum inhibitory concentration (MIC) determination.
Results
The most common Gram-negative and Gram-positive BSI-causing bacteria were Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), respectively. The isolation rate of E. coli dropped sharply from 37.33% in 2015–2016 to 15.37% in 2023–2024 (P < 0.01). E. coli displayed the highest sensitivity rates to imipenem, meropenem, and amikacin, with sensitivity rates exceeding 90.00%. The dramatic decreasing trends were observed for Klebsiella pneumoniae (K. pneumoniae) resistance to piperacillin/tazobactam (TZP), cephalosporins, imipenem, meropenem, tobramycin, and levofloxacin. S. aureus had a relatively high resistance rate to penicillin G, and the resistance rate of S. aureus to levofloxacin and moxifloxacin appeared to be rising. The isolation rate of methicillin-resistant S. aureus (MRSA) ranged from 25.00% to 40.00%. Kaplan–Meier survival analysis showed that Acinetobacter baumannii (A. baumannii) infection was associated with a higher 30-day mortality than other infections.
Conclusions
The isolation rate of E. coli exhibited a striking decreasing trend in our retrospective study. The resistance rate of K. pneumoniae to TZP, cephalosporins, imipenem, meropenem, tobramycin, and levofloxacin decreased significantly. The resistance rate of E. coli to carbapenems remained low, and the isolation rate of MRSA was relatively stable during the 10 years.
Supplementary Information
The online version contains supplementary material available at 10.1186/s12879-026-13427-y.
Keywords: Bloodstream infection, Antimicrobial resistance, Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae
Introduction
Bloodstream infections (BSIs) are deadly conditions caused by various pathogenic microorganisms in the bloodstream, including bacteria and fungi [1, 2], and lead to 6 million deaths annually worldwide [3]. The incidence of BSIs ranges from 122 to 220 cases/100,000 population yearly, with roughly 17% mortality within 30 days of a positive blood culture [1], and the rates gradually increase over time [4, 5]. BSIs have become a major public health problem.
In terms of pathogenesis, BSIs may relate to growth of pathogenic microorganisms within vessels, colonization of secondary sites, and persistent disease in other affected tissues [6]. These pathogenic microorganisms mainly include bacterial pathogens such as E. coli, S. aureus, and S. pneumoniae, and the fungal pathogen C. albicans [7]. BSIs can trigger an immediate and intense inflammatory reaction, and contribute to sepsis, which is defined as systemic inflammatory response syndrome to an infection [8].
BSIs are common in hospitals and are major causes of mortality in admissions, especially in patients with higher age and immunodeficiency [9–11]. Thus, continually monitoring the etiology and antibiotic resistance trends of pathogens causing BSIs could provide key information for empiric antibiotic treatment strategies, emerging resistance threats, and prevention schemes to decrease mortality and morbidity of BSIs in hospitals.
At present, data on BSIs and antimicrobial resistance patterns in Chinese medicine hospitals are relatively limited. Moreover, given that the use of antimicrobial drugs in traditional Chinese medicine hospitals may differ from that in Western medical institutions, there are significant disparities in regional data regarding the epidemiology of BSIs and antimicrobial resistance. Thus, the aim of the current study was to fill this gap by retrospectively analyzing the epidemiological and antimicrobial susceptibility profiles of BSI patients during the past 10 years in a tertiary-care traditional Chinese medicine hospital.
Methods
Collection of isolates
In this study, a total of 38,220 blood culture specimens were routinely taken from patients with fever or suspicion of sepsis during the period from 2015 to 2024 at Longhua hospital affiliated to Shanghai University of Traditional Chinese Medicine. To identify the presence of microbial pathogens, from January 2015 to December 2024, a set of anaerobic/aerobic blood culture bottles were taken from each patient’s left and right hands, with a total of 4 bottles, a BACTEC™ FX-200 blood culture system (BD Diagnostics, Sparks, MD, USA) instrument was used. Blood samples (8–10 mL per bottle) were taken from the patients. The blood culture bottles were cultivated for up to 5 days for bacteria and for up to 7 days for fungi. The incubation period was prolonged when a slow-growing pathogen was suspected. When positive culture specimens appeared, the bottle mouth was fully disinfected, and blood was collected by sterile needle for smear, Gram stain, and Wrights stain were performed, and the specimens were inoculated on blood agar (5% sheep blood) for subculture.
Isolate identification and antimicrobial susceptibility testing
Identification of isolates was performed using a microflex LT/SH matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry (MS) system (Bruker, Germany). Antimicrobial susceptibility testing was carried out using a VITEK®2 Compact system (bioMérieux, France). For Gram-negative bacteria, two types of antimicrobial susceptibility test cards, VITEK®2 AST-N335 and AST-XN04, were used. While for Gram-positive bacteria, the VITEK®2 AST-P639 test card was employed. In line with the Clinical and Laboratory Standards Institute (CLSI) guidelines, minimum inhibitory concentration (MIC) determination was performed, and the results were interpreted on the basis of the CLSI standards, except for tigecycline, for which the US Food and Drug Administration (FDA) criteria were used.
Statistical analysis
Antimicrobial susceptibility data were analyzed using VITEK 2 software. Only the first isolate of a given species from a patient was analyzed in line with the CLSI. IBM’s SPSS software version 29.0 (IBM, Armonk, NY, USA) was used to perform statistical analysis. An overall trend in the distribution of bacteria and antimicrobial susceptibility was analyzed using the linear-by-linear association (LLA) test. In IBM’s SPSS software, the data need to be organized in the form of a contingency table. Then, click “Analysis” > “Descriptive Statistics” > “Cross Tabulation”. After selecting the “Statistics” option, the output result will include the LLA test results. A P-value lower than 0.05 is considered to be statistically significant.
Results
Distribution of common pathogens in blood culture specimens
From January 2015 to December 2024, the overall positive rate of blood culture in our hospital was 5.94% (2,271/38,220). The average age of the entire sample population was 67.79 years, and 1,260 (55.48%) of the patients were male (Table 1). The distribution of the 2,271 isolated strains by department was as follows: 37 outpatients (1.63%), 305 intensive care unit (ICU) patients (13.43%), and 1,929 non-ICU admissions (84.94%). Among non-ICU, blood culture–positive strains from nephrology department (450, 19.82%) accounted for the highest proportion, followed by oncology department (260, 11.45%) and vascular surgery department (255, 11.23%).
Table 1.
Clinical basic information of patients with positive blood culture from 2015–2024
| Total | 2015–2016 | 2017–2018 | 2019–2020 | 2021–2022 | 2023–2024 | |
|---|---|---|---|---|---|---|
| (n = 2271) | (n = 217) | (n = 333) | (n = 473) | (n = 578) | (n = 670) | |
| Age, median ± SD | 67.79 ± 14.91 | 68.94 ± 14.7 | 68.1 ± 16.02 | 68.31 ± 15.45 | 66.85 ± 15.05 | 67.70 ± 13.87 |
| ≤ 60, n (%) | 634(27.92) | 57(26.27) | 99(29.73) | 122(25.79) | 170(29.41) | 186(27.76) |
| 61–70, n (%) | 645(28.40) | 62(28.57) | 81(24.32) | 134(28.33) | 184(31.83) | 184(27.46) |
| 71–80, n (%) | 516(22.72) | 36(16.59) | 69(20.72) | 105(22.20) | 122(21.11) | 184(27.46) |
| > 80, n (%) | 476(20.96) | 62(28.57) | 84(25.23) | 112(23.68) | 102(17.65) | 116(17.31) |
| Gender, n (%) | ||||||
| Male | 1260(55.48) | 110(50.69) | 185(55.56) | 263(55.60) | 330(57.09) | 372(55.52) |
| Female | 1011(44.52) | 107(49.31) | 148(44.44) | 210(44.40) | 248(42.91) | 298(44.48) |
| Department, n (%) | ||||||
| Nephrology Department | 450(19.82) | 10(4.61) | 28(8.41) | 85(17.97) | 168(29.07) | 159(23.73) |
| ICU | 305(13.43) | 20(9.22) | 36(10.81) | 78(16.49) | 104(17.99) | 67(10.00) |
| Oncology Department | 260(11.45) | 41(18.89) | 56(16.82) | 45(9.51) | 48(8.30) | 70(10.45) |
| Vascular Surgery Department | 255(11.23) | 10(4.61) | 49(14.71) | 55(11.63) | 66(11.42) | 75(11.19) |
| Emergency medicine | 164(7.22) | 17(7.83) | 27(8.11) | 38(8.03) | 34(5.88) | 48(7.16) |
| Gastrointestinal Surgery Department | 129(5.68) | 20(9.22) | 17(5.11) | 34(7.19) | 28(4.84) | 30(4.48) |
| Encephalopathy Department | 89(3.92) | 14(6.45) | 13(3.90) | 24(5.07) | 15(2.60) | 23(3.43) |
| Hepatology Department | 77(3.39) | 11(5.07) | 10(3.00) | 14(2.96) | 6(1.04) | 36(5.37) |
| Orthopedics Department | 71(3.13) | 12(5.53) | 20(6.01) | 11(2.33) | 10(1.73) | 18(2.69) |
| Pulmonology Department | 45(1.98) | 9(4.15) | 4(1.20) | 13(2.75) | 10(1.73) | 9(1.34) |
| Others | 426(18.76) | 53(24.42) | 66(19.82) | 76(16.07) | 89(15.40) | 142(21.19) |
As shown in Table 2, a total of 1,000 strains of Gram-negative bacteria, 1,185 strains of Gram-positive bacteria, and 86 strains of pathogenic fungi were isolated from the blood culture specimens. The most common pathogen isolated in the study was E. coli (17.97%), followed by S. aureus (13.96%), K. pneumoniae (10.70%), Staphylococcus epidermidis (S. epidermidis) (8.19%), Staphylococcus hominis (S. hominis) (4.32%), Enterococcus faecalis (E. faecalis) (2.82%), A. baumannii (2.60%), Enterococcus faecium (E. faecium) (2.51%), and Pseudomonas aeruginosa (P. aeruginosa) (1.98%). It is worth noting that the isolation rate of E. coli dropped sharply from 37.33% in 2015–2016 to 15.37% in 2023–2024 (P < 0.01; Table 2), and the isolation rate of CoNS significantly increased from 11.06% in 2015–2016 to 21.49% in 2023–2024 (P < 0.01; Table 2). Among CoNS, the isolation rate of S. epidermidis showed an upward trend, rising from 3.69% in 2015–2016 to 9.25% in 2023–2024 (P < 0.05; Table 2). Besides, the isolation rate of E. faecalis and E. faecium, the most common Enterococcus, changed a little, while the isolation frequency of Enterococcus was on the increase (P = 0.04; Table 2). The isolation frequency of Streptococcus dysgalactiae (S. dysgalactiae) showed a downward trend, decreasing from 3.23% in 2015–2016 to 0.30% in 2023–2024 (P < 0.01; Table 2). In addition, the isolation rate of pathogenic fungi Candida parapsilosis (C. parapsilosis) and Candida albicans (C. albicans) increased (P = 0.04 and P = 0.02, respectively; Table 2).
Table 2.
Distribution of common pathogens isolated from blood cultures from 2015–2024
| pathogen | 2015–2016 | 2017–2018 | 2019–2020 | 2021–2022 | 2023–2024 | All years | Z | P | ||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| n | % | n | % | n | % | n | % | n | % | n | % | |||
| Gram-negative bacteria | 134 | 61.75 | 159 | 47.75 | 215 | 45.45 | 209 | 36.16 | 283 | 42.24 | 1000 | 44.03 | 26.23 | < 0.01 |
| Escherichia coli | 81 | 37.33 | 76 | 22.82 | 83 | 17.55 | 65 | 11.25 | 103 | 15.37 | 408 | 17.97 | 52.85 | < 0.01 |
| Klebsiella pneumoniae | 23 | 10.60 | 43 | 12.91 | 52 | 10.99 | 58 | 10.03 | 67 | 10.00 | 243 | 10.70 | 1.10 | 0.23 |
| Acinetobacter baumannii | 5 | 2.30 | 7 | 2.10 | 21 | 4.44 | 17 | 2.94 | 9 | 1.34 | 59 | 2.60 | 1.44 | 0.23 |
| Pseudomonas aeruginosa | 4 | 1.84 | 6 | 1.80 | 8 | 1.69 | 10 | 1.73 | 17 | 2.54 | 45 | 1.98 | 0.69 | 0.41 |
| Enterobacter cloacae | 5 | 2.30 | 1 | 0.30 | 5 | 1.06 | 6 | 1.04 | 12 | 1.79 | 29 | 1.28 | 0.38 | 0.54 |
| Other | 16 | 7.37 | 26 | 7.81 | 46 | 9.73 | 53 | 9.17 | 75 | 11.19 | 216 | 9.51 | 3.78 | 0.05 |
| Gram-positive bacteria | 80 | 36.87 | 167 | 50.15 | 240 | 50.74 | 338 | 58.48 | 360 | 53.73 | 1185 | 52.18 | 17.58 | < 0.01 |
| Staphylococcus aureus | 24 | 11.06 | 51 | 15.32 | 70 | 14.80 | 92 | 15.92 | 80 | 11.94 | 317 | 13.96 | 0.13 | 0.72 |
| CoNS | 24 | 11.06 | 64 | 19.22 | 94 | 19.87 | 141 | 24.39 | 144 | 21.49 | 467 | 20.56 | 10.18 | < 0.01 |
| Staphylococcus epidermidis | 8 | 3.69 | 33 | 9.91 | 30 | 6.34 | 53 | 9.17 | 62 | 9.25 | 186 | 8.19 | 3.90 | < 0.05 |
| Staphylococcus hominis | 7 | 3.23 | 16 | 4.80 | 16 | 3.38 | 30 | 5.19 | 29 | 4.33 | 98 | 4.32 | 0.43 | 0.51 |
| Other | 9 | 4.15 | 15 | 4.50 | 48 | 10.15 | 58 | 10.03 | 53 | 7.91 | 183 | 8.06 | 5.09 | 0.02 |
| Enterococcus | 12 | 5.53 | 13 | 3.90 | 30 | 6.34 | 30 | 5.19 | 54 | 8.06 | 139 | 6.12 | 4.19 | 0.04 |
| Enterococcus faecalis | 7 | 3.23 | 8 | 2.40 | 11 | 2.33 | 13 | 2.25 | 25 | 3.73 | 64 | 2.82 | 0.69 | 0.41 |
| Enterococcus faecium | 5 | 2.30 | 5 | 1.50 | 11 | 2.33 | 12 | 2.08 | 24 | 3.58 | 57 | 2.51 | 2.74 | 0.10 |
| Other | 0 | 0.00 | 0 | 0.00 | 8 | 1.69 | 5 | 0.86 | 5 | 0.74 | 18 | 0.79 | 1.13 | 0.32 |
| Beta-hemolytic streptococci | 12 | 5.52 | 13 | 3.90 | 12 | 2.54 | 20 | 3.46 | 16 | 2.39 | 73 | 3.21 | 4.01 | 0.04 |
| Streptococcus dysgalactiae | 7 | 3.23 | 7 | 0.21 | 3 | 0.63 | 5 | 0.86 | 2 | 0.30 | 24 | 1.06 | 14.40 | < 0.01 |
| Streptococcus agalactiae | 4 | 1.84 | 3 | 0.90 | 5 | 1.06 | 0 | 0.00 | 6 | 0.89 | 18 | 0.79 | 2.16 | 0.15 |
| Other | 1 | 0.46 | 3 | 0.90 | 4 | 0.85 | 15 | 2.60 | 8 | 1.19 | 31 | 1.36 | 2.03 | 0.15 |
| Non-Beta-hemolytic streptococci | 4 | 1.84 | 12 | 3.60 | 21 | 4.44 | 15 | 2.60 | 26 | 3.88 | 78 | 3.43 | 0.43 | 0.51 |
| Streptococcus oralis | 0 | 0.00 | 3 | 0.90 | 11 | 2.33 | 5 | 0.86 | 14 | 2.09 | 33 | 1.45 | 3.17 | 0.08 |
| Streptococcus anginosus | 2 | 0.92 | 1 | 0.30 | 3 | 0.63 | 3 | 0.52 | 5 | 0.74 | 14 | 0.61 | 0.03 | 0.92 |
| Other | 2 | 0.92 | 8 | 2.40 | 7 | 1.48 | 7 | 1.21 | 7 | 1.04 | 31 | 1.37 | 0.86 | 0.35 |
| Pathogenic Fungi | 3 | 1.38 | 7 | 2.10 | 18 | 3.81 | 31 | 5.36 | 27 | 4.03 | 86 | 3.79 | 5.72 | 0.02 |
| Candida parapsilosis | 0 | 0.00 | 3 | 0.90 | 9 | 1.90 | 17 | 2.94 | 12 | 1.79 | 41 | 1.81 | 4.31 | 0.04 |
| Candida glabrata | 1 | 0.46 | 3 | 0.90 | 4 | 0.85 | 12 | 2.08 | 5 | 0.74 | 25 | 1.10 | 0.44 | 0.51 |
| Candida albicans | 0 | 0.00 | 0 | 0.00 | 2 | 0.42 | 0 | 0.00 | 7 | 1.04 | 9 | 0.40 | 5.82 | 0.02 |
| Other | 2 | 0.92 | 1 | 0.30 | 3 | 0.63 | 2 | 0.35 | 3 | 0.45 | 11 | 0.48 | 0.36 | 0.57 |
CoNS, coagulase-negative staphylococci; Z-value, a test statistic for Z-tests.
In summary, the isolation rate of Gram-negative bacteria showed a notably decreasing trend (P < 0.01; Table 2), whereas the isolation rate of Gram-positive bacteria and fungi showed an increasing trend (P < 0.01 and P = 0.02, respectively; Table 2).
Antimicrobial susceptibility testing
Antimicrobial susceptibility testing showed that isolated strains of E. coli showed a high level of resistance to cefazolin (44.62%–62.14%), levofloxacin (44.44%–54.22%), and ceftriaxone (45.63%–48.68%). The resistance rate of E. coli to ciprofloxacin exhibited a rising trend (P = 0.04; Table 3), whereas the resistance rate to tobramycin showed a downward trend (P = 0.03; Table 3). In addition, the frequency of carbapenem-resistant isolates of E. coli was analyzed during 2015–2024 and ranged from 0 to 7.41% (Fig. 1A). The resistance rates of K. pneumoniae to cefazolin, levofloxacin, ceftriaxone, and trimethoprim/sulfamethoxazole (SXT) were lower than those of E. coli, but the resistance rates to ceftazidime, aztreonam, piperacillin/tazobactam (TZP), tobramycin, imipenem, meropenem and amikacin were relatively higher (Tables 3 and 4). It is worth noting that the resistance rates of K. pneumoniae to TZP, cefazolin, ceftazidime, ceftriaxone, cefotetan, imipenem, meropenem, tobramycin, and levofloxacin showed a remarkable decreasing trend (P < 0.05; Table 4). The isolation rate of carbapenem-resistant K. pneumoniae (CRKP) strains showed a declining trend (Fig. 1A). Furthermore, the data showed that the frequency of CRKP isolates was notably higher in ICU patients than non-ICU patients (Figs. 1B, C).
Table 3.
Resistance rates to common antimicrobial agents of E. coli isolated from blood cultures from 2015–2024
| Antimicrobial agents | 2015–2016(n = 81) | 2017–2018 (n = 76) | 2019–2020 (n = 83) | 2021–2022 (n = 65) | 2023–2024 (n = 103) | Z | P | |||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| n | % | n | % | n | % | n | % | n | % | |||
| Cefazolin | 39 | 48.15 | 40 | 52.63 | 39 | 46.99 | 29 | 44.62 | 64 | 62.14 | 2.20 | 0.14 |
| Levofloxacin | 36 | 44.44 | 34 | 44.74 | 45 | 54.22 | 29 | 44.62 | 55 | 53.40 | 1.31 | 0.25 |
| Ceftriaxone | 37 | 45.68 | 37 | 48.68 | 38 | 45.78 | 31 | 47.69 | 47 | 45.63 | 0.01 | 0.93 |
| Ciprofloxacin | 39 | 48.15 | 31 | 40.79 | 24 | 28.92 | 29 | 44.62 | 63 | 61.17 | 4.41 | 0.04 |
| SXT | 33 | 40.74 | 29 | 38.16 | 40 | 48.19 | 30 | 46.15 | 33 | 32.04 | 0.72 | 0.40 |
| Aztreonam | 31 | 38.27 | 25 | 32.89 | 12 | 14.46 | 13 | 20.00 | 29 | 28.16 | 3.59 | 0.06 |
| Cefepime | 17 | 20.99 | 21 | 27.63 | 22 | 26.51 | 16 | 24.62 | 33 | 32.04 | 1.93 | 0.17 |
| Gentamicin | 25 | 30.86 | 14 | 18.42 | 19 | 22.89 | 12 | 18.46 | 28 | 27.18 | 0.10 | 0.76 |
| Ceftazidime | 21 | 25.93 | 23 | 30.26 | 16 | 19.28 | 11 | 16.92 | 21 | 20.39 | 2.47 | 0.12 |
| Tobramycin | 11 | 13.58 | 14 | 18.42 | 0 | 0.00 | 4 | 6.15 | 8 | 7.77 | 4.99 | 0.03 |
| TZP | 2 | 2.47 | 2 | 2.63 | 8 | 9.64 | 8 | 12.31 | 7 | 6.80 | 3.52 | 0.06 |
| CSL | 6 | 7.41 | 3 | 3.95 | 4 | 4.82 | 4 | 6.15 | 6 | 5.83 | 0.02 | 0.90 |
| Imipenem | 6 | 7.41 | 2 | 2.63 | 0 | 0.00 | 4 | 6.15 | 6 | 5.83 | 0.01 | 0.94 |
| Meropenem | 6 | 7.41 | 2 | 2.63 | 0 | 0.00 | 4 | 6.15 | 6 | 5.83 | 0.01 | 0.94 |
| Amikacin | 2 | 2.47 | 0 | 0.00 | 4 | 4.82 | 1 | 1.54 | 0 | 0.00 | 0.86 | 0.35 |
CSL, Cefoperazone/Sulbactam; TZP, Piperacillin/Tazobactam; SXT, Trimethoprim/Sulfamethoxazole; Z-value, a test statistic for Z-tests
Fig. 1.
Trends in common multidrug-resistant isolates from blood cultures from 2015–2024. (A) all patients including inpatients and outpatients; (B) intensive care unit (ICU) inpatients; and (C) non-ICU inpatients. CRE, carbapenem-resistant Escherichia coli; CRAB, carbapenem-resistant Acinetobacter baumannii; CRKP, carbapenem-resistant Klebsiella pneumoniae; MRSA, methicillin-resistant Staphylococcus aureus
Table 4.
Resistance rates to common antimicrobial agents of K. pneumoniae isolated from blood cultures from 2015–2024
| Antimicrobial agents | 2015–2016(n = 23) | 2017–2018 (n = 43) | 2019–2020 (n = 52) | 2021–2022 (n = 58) | 2023–2024 (n = 67) | Z | P | |||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| n | % | n | % | n | % | n | % | n | % | |||
| Ciprofloxacin | 11 | 47.83 | 17 | 39.53 | 18 | 34.62 | 15 | 25.86 | 24 | 35.82 | 1.52 | 0.22 |
| Ceftazidime | 11 | 47.83 | 19 | 44.19 | 19 | 36.54 | 13 | 22.41 | 21 | 31.34 | 4.76 | 0.03 |
| Ceftriaxone | 9 | 39.13 | 19 | 44.19 | 22 | 42.31 | 12 | 20.69 | 20 | 29.85 | 4.17 | 0.04 |
| Levofloxacin | 11 | 47.83 | 18 | 41.86 | 20 | 38.46 | 13 | 22.41 | 18 | 26.87 | 6.71 | 0.01 |
| Cefazolin | 11 | 47.83 | 17 | 39.53 | 19 | 36.54 | 14 | 24.14 | 20 | 29.85 | 4.01 | < 0.05 |
| Cefepime | 9 | 39.13 | 17 | 39.53 | 20 | 38.46 | 12 | 20.69 | 21 | 31.34 | 2.28 | 0.13 |
| Aztreonam | 9 | 39.13 | 17 | 39.53 | 18 | 34.62 | 13 | 22.41 | 21 | 31.34 | 1.87 | 0.17 |
| Cefotetan | 9 | 39.13 | 17 | 39.53 | 18 | 34.62 | 13 | 22.41 | 12 | 17.91 | 8.73 | < 0.01 |
| TZP | 9 | 39.13 | 17 | 39.53 | 19 | 36.54 | 13 | 22.41 | 9 | 13.43 | 12.54 | < 0.01 |
| Tobramycin | 9 | 39.13 | 17 | 39.53 | 18 | 34.62 | 10 | 17.24 | 7 | 10.45 | 17.24 | < 0.01 |
| Imipenem | 9 | 39.13 | 14 | 32.56 | 17 | 32.69 | 11 | 18.97 | 7 | 10.45 | 13.10 | < 0.01 |
| Meropenem | 9 | 39.13 | 14 | 32.56 | 17 | 32.69 | 11 | 18.97 | 7 | 10.45 | 13.10 | < 0.01 |
| SXT | 4 | 17.39 | 13 | 30.23 | 7 | 13.46 | 7 | 12.07 | 21 | 31.34 | 0.50 | 0.48 |
| Amikacin | 5 | 21.74 | 7 | 16.28 | 10 | 19.23 | 8 | 13.79 | 6 | 8.96 | 2.84 | 0.09 |
TZP, Piperacillin/Tazobactam; SXT, Trimethoprim/Sulfamethoxazole; Z-value, a test statistic for Z-tests
The antimicrobial susceptibility data indicated that A. baumannii had a high level of resistance to cefotetan, cefuroxime axetil, and cefpodoxime. During the study period, the resistance rates of A. baumannii to imipenem, meropenem, cefepime, and minocycline showed a significant downward trend from 2017–2018 to 2023–2024 (P < 0.05; Table 5). The isolation rate of carbapenem-resistant A. baumannii (CRAB) strains increased from 60.00% in 2015–2016 to 85.71% in 2017–2018, then decreased to 11.11% in 2023–2024 (Fig. 1A). In addition, P. aeruginosa showed a high level of resistance to cefotetan and cefpoxime. The resistance rates of P. aeruginosa to cefotaxime, ampicillin, tetracycline, and ceftizoxime were on the rise (P < 0.01; Table 6).
Table 5.
Resistance rates to common antimicrobial agents of A. baumannii isolated from blood cultures from 2015–2024
| Antimicrobial agents | 2015–2016(n = 5) | 2017–2018 (n = 7) | 2019–2020 (n = 21) | 2021–2022 (n = 17) | 2023–2024 (n = 9) | Z | P | |||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| n | % | n | % | n | % | n | % | n | % | |||
| Cefotetan | 5 | 100.00 | 7 | 100.00 | 16 | 76.19 | 14 | 82.35 | 9 | 100.00 | 0.04 | 0.87 |
| Cefuroxime Axetil | 5 | 100.00 | 7 | 100.00 | 16 | 76.19 | 14 | 82.35 | 9 | 100.00 | 0.04 | 0.87 |
| Cefpodoxime | 5 | 100.00 | 7 | 100.00 | 16 | 76.19 | 14 | 82.35 | 9 | 100.00 | 0.04 | 0.87 |
| Imipenem | 3 | 60.00 | 6 | 85.71 | 15 | 71.43 | 11 | 64.71 | 1 | 11.11 | 5.53 | 0.02 |
| Meropenem | 3 | 60.00 | 6 | 85.71 | 15 | 71.43 | 11 | 64.71 | 1 | 11.11 | 5.53 | 0.02 |
| Ceftazidime | 2 | 40.00 | 6 | 85.71 | 15 | 71.43 | 12 | 70.59 | 1 | 11.11 | 2.71 | 0.13 |
| Tetracycline | 2 | 40.00 | 6 | 85.71 | 15 | 71.43 | 11 | 64.71 | 2 | 22.22 | 1.99 | 0.20 |
| Piperacillin | 2 | 40.00 | 6 | 85.71 | 15 | 71.43 | 11 | 64.71 | 1 | 11.11 | 3.22 | 0.08 |
| Ticacillin | 2 | 40.00 | 6 | 85.71 | 15 | 71.43 | 11 | 64.71 | 1 | 11.11 | 3.22 | 0.08 |
| Ampicillin | 2 | 40.00 | 6 | 85.71 | 15 | 71.43 | 11 | 64.71 | 1 | 11.11 | 3.22 | 0.08 |
| Cefotaxime | 2 | 40.00 | 6 | 85.71 | 15 | 71.43 | 11 | 64.71 | 1 | 11.11 | 3.22 | 0.08 |
| Ceftizoxime | 2 | 40.00 | 6 | 85.71 | 15 | 71.43 | 11 | 64.71 | 1 | 11.11 | 3.22 | 0.08 |
| Moxifloxacin | 2 | 40.00 | 6 | 85.71 | 15 | 71.43 | 11 | 64.71 | 1 | 11.11 | 3.22 | 0.08 |
| Ciprofloxacin | 2 | 40.00 | 6 | 85.71 | 15 | 71.43 | 11 | 64.71 | 1 | 11.11 | 3.22 | 0.08 |
| Doxycycline | 2 | 40.00 | 6 | 85.71 | 15 | 71.43 | 11 | 64.71 | 1 | 11.11 | 3.22 | 0.08 |
| Levofloxacin | 0 | 0.00 | 6 | 85.71 | 15 | 71.43 | 11 | 64.71 | 1 | 11.11 | 0.50 | 0.49 |
| Cefepime | 2 | 40.00 | 6 | 85.71 | 13 | 61.90 | 8 | 47.06 | 1 | 11.11 | 4.42 | 0.04 |
| Minocycline | 2 | 40.00 | 6 | 85.71 | 10 | 47.62 | 7 | 41.18 | 0 | 0.00 | 6.10 | 0.01 |
| SXT | 1 | 20.00 | 5 | 71.43 | 10 | 47.62 | 6 | 35.29 | 1 | 11.11 | 2.01 | 0.16 |
| Cefoperazone | 2 | 40.00 | 3 | 42.86 | 3 | 14.29 | 9 | 52.94 | 1 | 11.11 | 0.14 | 0.81 |
| Tigecycline | 2 | 40.00 | 2 | 28.57 | 4 | 19.05 | 6 | 35.29 | 0 | 0.00 | 1.33 | 0.28 |
| Colistin | 1 | 20.00 | 5 | 71.43 | 1 | 4.76 | 2 | 11.76 | 0 | 0.00 | 6.12 | 0.02 |
SXT, Trimethoprim/Sulfamethoxazole; Z-value, a test statistic for Z-tests
Table 6.
Resistance rates to common antimicrobial agents of P. aeruginosa isolated from blood cultures from 2015–2024
| Antimicrobial agents | 2015–2016(n = 4) | 2017–2018 (n = 6) | 2019–2020 (n = 8) | 2021–2022 (n = 10) | 2023–2024 (n = 17) | Z | P | |||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| n | % | n | % | n | % | n | % | n | % | |||
| Cefotetan | 3 | 75.00 | 5 | 83.33 | 2 | 25.00 | 9 | 90.00 | 17 | 100.00 | 4.89 | 0.04 |
| Cefpoxime | 3 | 75.00 | 5 | 83.33 | 2 | 25.00 | 9 | 90.00 | 17 | 100.00 | 4.89 | 0.04 |
| Cefotaxime | 0 | 0.00 | 3 | 50.00 | 2 | 25.00 | 9 | 90.00 | 16 | 94.12 | 17.86 | < 0.01 |
| Ampicillin | 0 | 0.00 | 3 | 50.00 | 2 | 25.00 | 6 | 60.00 | 17 | 100.00 | 17.48 | < 0.01 |
| Tetracycline | 0 | 0.00 | 3 | 50.00 | 2 | 25.00 | 5 | 50.00 | 16 | 94.12 | 13.92 | < 0.01 |
| Ceftizoxime | 0 | 0.00 | 3 | 50.00 | 2 | 25.00 | 5 | 50.00 | 16 | 94.12 | 13.92 | < 0.01 |
| Cefepime | 0 | 0.00 | 3 | 50.00 | 2 | 25.00 | 8 | 80.00 | 0 | 0.00 | 0.80 | 0.40 |
| Moxifloxacin | 0 | 0.00 | 3 | 50.00 | 2 | 25.00 | 2 | 20.00 | 4 | 23.53 | 0.01 | 1.00 |
| Ticacillin | 0 | 0.00 | 3 | 50.00 | 3 | 37.50 | 3 | 30.00 | 2 | 11.76 | 0.74 | 0.45 |
| Ciprofloxacin | 0 | 0.00 | 2 | 33.33 | 2 | 25.00 | 2 | 20.00 | 3 | 17.65 | 0.00 | 1.00 |
| Levofloxacin | 1 | 25.00 | 0 | 0.00 | 2 | 25.00 | 2 | 20.00 | 4 | 23.53 | 0.31 | 0.68 |
| Doripenem | 0 | 0.00 | 3 | 50.00 | 2 | 25.00 | 1 | 10.00 | 1 | 5.88 | 2.03 | 0.17 |
| Cefoperazone | 0 | 0.00 | 2 | 33.33 | 2 | 25.00 | 1 | 10.00 | 0 | 0.00 | 2.32 | 0.16 |
| Ceftazidime | 0 | 0.00 | 2 | 33.33 | 2 | 25.00 | 1 | 10.00 | 0 | 0.00 | 2.32 | 0.16 |
| Piperacillin | 0 | 0.00 | 2 | 33.33 | 2 | 25.00 | 1 | 10.00 | 0 | 0.00 | 2.32 | 0.16 |
| Tobramycin | 0 | 0.00 | 2 | 33.33 | 2 | 25.00 | 1 | 10.00 | 0 | 0.00 | 2.32 | 0.16 |
| Colistin | 0 | 0.00 | 0 | 0.00 | 1 | 12.50 | 0 | 0.00 | 0 | 0.00 | 0.25 | 0.78 |
| Imipenem | 0 | 0.00 | 0 | 0.00 | 0 | 0.00 | 0 | 0.00 | 0 | 0.00 | - | - |
| Meropenem | 0 | 0.00 | 0 | 0.00 | 0 | 0.00 | 0 | 0.00 | 0 | 0.00 | - | - |
Z-value, a test statistic for Z-tests
S. aureus had a relatively high resistance rate to penicillin G, but it showed a downward trend (P = 0.03; Table 7). The resistance rate of S. aureus to levofloxacin and moxifloxacin appeared to be rising (P = 0.03 and P = 0.02, respectively; Table 7). S. aureus was extremely sensitive to linezolid, vancomycin, teicoplanin, and tigecycline, and no resistant strains were found (Table 7). The frequency of methicillin-resistant S. aureus (MRSA) increased from 25.00% in 2015–2016 to 40.00% in 2023–2024 (Fig. 1A), and the proportion of MRSA isolates in ICU patients was relatively higher (Figs. 1B, C). E. faecium isolates showed significantly higher resistance rates to penicillin G, levofloxacin, moxifloxacin, and erythromycin than E. faecalis isolates (Tables 8 and 9). Similar to S. aureus, the resistance rates of E. faecalis and E. faecium isolates to linezolid, vancomycin, and tigecycline were 0.00.
Table 7.
Resistance rates to common antimicrobial agents of S. aureus isolated from blood cultures from 2015–2024
| Antimicrobial agents | 2015–2016(n = 24) | 2017–2018 (n = 51) | 2019–2020 (n = 70) | 2021–2022 (n = 92) | 2023–2024 (n = 80) | Z | P | |||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| n | % | n | % | n | % | n | % | n | % | |||
| Penicillin G | 22 | 91.67 | 50 | 98.04 | 51 | 72.86 | 79 | 85.87 | 62 | 77.50 | 5.01 | 0.03 |
| Erythromycin | 12 | 50.00 | 18 | 35.29 | 21 | 30.00 | 45 | 48.91 | 32 | 40.00 | 0.23 | 0.63 |
| Oxacillin | 6 | 25.00 | 18 | 35.29 | 21 | 30.00 | 34 | 36.96 | 32 | 40.00 | 1.88 | 0.17 |
| Levofloxacin | 1 | 4.17 | 16 | 31.37 | 9 | 12.86 | 28 | 30.43 | 24 | 30.00 | 4.59 | 0.03 |
| Moxifloxacin | 1 | 4.17 | 8 | 15.69 | 8 | 11.43 | 21 | 22.83 | 18 | 22.50 | 5.64 | 0.02 |
| Gentamicin | 3 | 12.50 | 6 | 11.76 | 5 | 7.14 | 11 | 11.96 | 8 | 10.00 | 0.02 | 0.89 |
| SXT | 0 | 0.00 | 3 | 5.88 | 2 | 2.86 | 3 | 3.26 | 3 | 3.75 | 0.03 | 0.86 |
| Rifampicin | 1 | 4.17 | 0 | 0.00 | 0 | 0.00 | 1 | 1.09 | 0 | 0.00 | 1.27 | 0.26 |
| Linezolid | 0 | 0.00 | 0 | 0.00 | 0 | 0.00 | 0 | 0.00 | 0 | 0.00 | - | - |
| Vancomycin | 0 | 0.00 | 0 | 0.00 | 0 | 0.00 | 0 | 0.00 | 0 | 0.00 | - | - |
| Teicoplanin | 0 | 0.00 | 0 | 0.00 | 0 | 0.00 | 0 | 0.00 | 0 | 0.00 | - | - |
| Tigecycline | 0 | 0.00 | 0 | 0.00 | 0 | 0.00 | 0 | 0.00 | 0 | 0.00 | - | - |
SXT, Trimethoprim/Sulfamethoxazole; Z-value, a test statistic for Z-tests
Table 8.
Resistance rates to common antimicrobial agents of E. faecalis isolated from blood cultures from 2015–2024
| Antimicrobial agents | 2015–2016(n = 7) | 2017–2018 (n = 8) | 2019–2020 (n = 11) | 2021–2022 (n = 13) | 2023–2024 (n = 25) | Z | P | |||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| n | % | n | % | n | % | n | % | n | % | |||
| Erythromycin | 4 | 57.14 | 6 | 75.00 | 5 | 45.45 | 4 | 30.77 | 10 | 40.00 | 2.38 | 0.13 |
| Moxifloxacin | 3 | 42.86 | 3 | 37.50 | 3 | 27.27 | 2 | 15.38 | 9 | 36.00 | 0.12 | 0.77 |
| Gentamicin | 2 | 28.57 | 6 | 75.00 | 2 | 18.18 | 2 | 15.38 | 8 | 32.00 | 0.87 | 0.39 |
| Levofloxacin | 3 | 42.86 | 1 | 12.50 | 2 | 18.18 | 2 | 15.38 | 9 | 36.00 | 0.18 | 0.69 |
| Penicillin G | 1 | 14.29 | 1 | 12.50 | 1 | 9.09 | 2 | 15.38 | 4 | 16.00 | 0.10 | 0.80 |
| Linezolid | 0 | 0.00 | 0 | 0.00 | 0 | 0.00 | 0 | 0.00 | 0 | 0.00 | - | - |
| Vancomycin | 0 | 0.00 | 0 | 0.00 | 0 | 0.00 | 0 | 0.00 | 0 | 0.00 | - | - |
| Tigecycline | 0 | 0.00 | 0 | 0.00 | 0 | 0.00 | 0 | 0.00 | 0 | 0.00 | - | - |
Z-value, a test statistic for Z-tests
Table 9.
Resistance rates to common antimicrobial agents of E. faecium isolated from blood cultures from 2015–2024
| Antimicrobial agents | 2015–2016(n = 5) | 2017–2018 (n = 5) | 2019–2020 (n = 11) | 2021–2022 (n = 12) | 2023–2024 (n = 24) | Z | P | |||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| n | % | n | % | n | % | n | % | n | % | |||
| Penicillin G | 4 | 80.00 | 4 | 80.00 | 10 | 90.91 | 12 | 100.00 | 20 | 83.33 | 0.03 | 0.88 |
| Levofloxacin | 3 | 60.00 | 4 | 80.00 | 10 | 90.91 | 10 | 83.33 | 20 | 83.33 | 0.58 | 0.52 |
| Moxifloxacin | 3 | 60.00 | 4 | 80.00 | 10 | 90.91 | 10 | 83.33 | 20 | 83.33 | 0.58 | 0.52 |
| Erythromycin | 4 | 80.00 | 4 | 80.00 | 7 | 63.64 | 12 | 100.00 | 13 | 54.17 | 1.50 | 0.23 |
| Gentamicin | 3 | 60.00 | 3 | 60.00 | 5 | 45.45 | 6 | 50.00 | 9 | 37.50 | 1.24 | 0.27 |
| Linezolid | 0 | 0.00 | 0 | 0.00 | 0 | 0.00 | 0 | 0.00 | 0 | 0.00 | - | - |
| Vancomycin | 0 | 0.00 | 0 | 0.00 | 0 | 0.00 | 0 | 0.00 | 0 | 0.00 | - | - |
| Tigecycline | 0 | 0.00 | 0 | 0.00 | 0 | 0.00 | 0 | 0.00 | 0 | 0.00 | - | - |
Z-value, a test statistic for Z-tests
Correlation between BSIs and prognosis
Mortality was evaluated 30 days after diagnosis to provide a comprehensive understanding of the prognosis. The overall in-hospital mortality rate among the patients with BSIs was 5.67% (38/670) in 2023–2024. Patients infected with A. baumannii, E. coli, K. pneumoniae, P. aeruginosa, and E. cloacae had an overall mortality rate of 33.33% (3/9), 7.77% (8/103), 19.40% (13/67), 17.65% (3/17), and 25.00% (3/12), respectively. Patients infected with S. aureus and CoNS had mortality rates of 8.75% (7/80) and 0.69% (1/144), respectively. Kaplan–Meier survival analysis showed that A. baumannii infection led to a higher 30-day mortality than infections caused by other bacteria (P = 0.01; Fig. 2).
Fig. 2.
Analysis of thirty-day patient survival trends for bloodstream infections caused by different pathogen. Kaplan–Meier survival curve was used to estimate the survival function from lifetime data. The sample size was 670 participants. Statistical significance was assessed using the Log rank test to compare survival differences between groups, with P < 0.05 indicating significant differences
Discussion
BSIs originate from pathogens in the environment and endogenous colonization or infection, leading to intravascular lesions that can spread to any organ that typically filters the blood, such as the lung or bladder [2]. They pose a serious threat to public health and receive increasing attention. Given factors such as population aging and the continuous emergence of antibiotic resistance, the number of patients at risk will likely increase, which highlights the importance of exploring the distribution and drug sensitivity of common pathogens in blood culture specimens.
In this study, we retrospectively analyzed the prevalence and drug resistance of BSI-related pathogens in a large tertiary traditional Chinese medicine hospital in Shanghai from 2015 to 2024. The surveillance data indicated E. coli (17.97%), followed closely by S. aureus (13.96%) and K. pneumoniae (10.70%), as the major identified pathogens from BSIs in our hospital. In line with previous reports [12, 13], our study demonstrated that E. coli was the most frequently isolated bacillus causing BSIs. Nevertheless, some studies have shown that S. aureus is the most common pathogen causing BSI infection [14, 15]. It is noteworthy that the isolation rate of E. coli exhibited a striking decreasing trend, which is inconsistent with previous surveys [16].
Given that E. coli is a major cause of BSIs, its antibiotic resistance rate has attracted great attention. The antimicrobial susceptibility monitoring data showed that resistance rates of E. coli to most antibiotics changed a little during the observation period. The resistance rates of E. coli to tobramycin showed a downward trend. However, increased resistance rate to ciprofloxacin was observed, which was probably owing to the excessive use of quinolones. We found that imipenem, meropenem, and amikacin were still the most effective antibiotics against E. coli isolates, and the susceptibility rates exceeded 90.00%. Similar phenomenon has been observed in another report [17]. In addition, an extremely low level of E. coli resistance to carbapenems was observed in this monitoring period, which is consistent with a previous study [18].
It has been shown that, after E. coli, K. pneumoniae is a significant pathogen causing BSIs [19, 20]. High virulence and carbapenem resistance (CR) have become two distinct evolutionary directions leading to the successful prevalence of high-risk K. pneumoniae lineages [21, 22]. CRKP emerges as one of the most serious problems among BSIs and a looming threat in clinical settings. China Antimicrobial Surveillance Network (CHINET) surveillance of bacterial resistance showed that CRKP increased significantly from 2005 to 2014 [23]. Liu et al. [18] reported a remarkable increasing trend in K. pneumoniae resistance to carbapenems, from 6.70% in 2010–2011 to 56.70% in 2018–2019. Interestingly, the isolation rate of CRKP strains decreased from 39.13% in 2015–2016 to 10.45% in 2023–2024 in our study. And dramatic decreasing trends were observed in K. pneumoniae resistance to TZP, cephalosporins, imipenem, tobramycin, and levofloxacin, suggesting a reduction of multidrug resistance (MDR) K. pneumoniae and CRKP in BSIs. This might be closely related to combination of Chinese medicine with antibacterial drugs for BSIs treatment in our hospital. Previous studies have shown that traditional Chinese medicine exploits good antibacterial effects by inhibiting or killing bacteria, regulating the body’s immunity, reducing bacterial resistance, and delaying or even reversing bacterial resistance [24, 25].
A. baumannii and P. aeruginosa were the seventh (2.60%) and ninth (1.98%) most commonly isolated organisms associated with BSIs in our study. A. baumannii is one of the main pathogens causing hospital-acquired infections worldwide, and it is generally very resistant to commonly used antibiotics such as meropenem and imipenem [26]. According to the CHINET, the resistance rate of A. baumannii to meropenem and imipenem in China has increased from 39.00% to 31.00% in 2005 to 69.00% and 68.10% in 2020 [23, 27]. The transmission of CRAB is currently the main challenge in clinical treatment. The prevalence of CRAB ranged from 11.11% to 85.71% during the monitoring period, which was not significantly different from that in other studies [18, 28]. It has been suggested that the poor prognosis of patients suffering from A. baumanii-associated BSIs stems from the difficulty of treating the infections, leading to high mortality [29, 30]. Similarly, A. baumannii infection led to a high 30-day mortality in our study. Multiple studies have shown that P. aeruginosa is highly sensitive to common antibiotics [31, 32]. However, the resistance rates of P. aeruginosa to cefotaxime, ampicillin, tetracycline, and ceftizoxime showed a significant upward trend. Interestingly, over the past 10 years, our hospital has never encountered any strains of P. aeruginosa resistant to carbapenem antibiotics. This might be related to the medication regimen used by patients suffering from P. aeruginosa infection. Following P. aeruginosa, there were 29 E. cloacae strains and 216 other Gram-negative bacteria strains. Proteus mirabilis, Burkholderia cepacian, Klebsiella oxytoca, Serratia marcescens, and Enterobacter asburiae were the major pathogen among the 216 strains (Supplementary Table S1). We noticed that the expansion of strain library in MALDI-TOF MS system has led to the identification of an increasing number of new strains in BSIs.
In our investigation, S. aureus was identified as the predominant Gram-positive bacterium in BSIs. The isolation rate of MRSA was relatively stable and increased slightly from 25.00% to 40.00%. Our result is inconsistent with other regional and national surveillance, which reported a significant decline of MRSA prevalence [18, 33]. This phenomenon might be due to the small sample size (coming from a single center), and it was not representative. S. epidermidis and S. hominis, the major CoNS, were the fourth and fifth most prevalent organisms associated with BSIs after K. pneumoniae. For many years, CoNS have not been regarded as the causative agents of BSIs and were usually considered to be contamination. Identification of the infection source can be rather challenging, as these microorganisms belong to the normal flora on the human skin, and their transmission may occur through the hands of healthcare workers [34]. However, in recent years, the CoNS isolates have gradually been considered as important clinical pathogens causing BSIs and a high mortality rate [35]. S. epidermidis and S. hominis showed high resistance to penicillin G, oxacillin, erythromycin, and levofloxacin. Besides, linezolid, vancomycin, and tigecycline were found to be highly effective against S. epidermidis and S. hominis in our study (Supplementary Tables S2 and S3).
E. faecalis and E. faecium were the sixth (2.82%) and eighth (2.51%) most prevalent organisms associated with BSIs in the monitoring study. During the period from 2015 to 2024, our hospital did not identify any strains of E. faecalis or E. faecium that were resistant to linezolid, vancomycin, and tigecycline. Therefore, vancomycin, linezolid, and tigecycline can be regarded as better options for treating Enterococcus that has developed resistance to commonly used antibiotics.
Several limitations of our study should be considered. First, the retrospective design carried risks of incomplete documentation of clinical details and microbiological data. Second, this was not a multicenter investigation, which may limit the generalizability of our findings. Third, the number of some isolates was too small to conduct reliable trend analysis of antimicrobial sensitivity. However, we firmly believe that we could address this gap regarding the epidemiology and antimicrobial sensitivity of BSIs isolated in traditional Chinese medicine hospitals by retrospectively analyzing data from patients at our hospital between 2015 and 2024.
Conclusions
We conducted a retrospective study of the distribution of pathogens causing BSIs and changes in their antimicrobial resistance at a large tertiary traditional Chinese medicine hospital in Shanghai. It was demonstrated that E. coli, S. aureus, and K. pneumoniae were the most common pathogens isolated from BSIs. The isolation rate of E. coli exhibited a striking decreasing trend, and the resistance rates of E. coli to cephalosporins and aztreonam hardly changed during these 10 years. It is noteworthy that the dramatic decreasing trends were observed in K. pneumoniae resistance to TZP, cephalosporins, imipenem, meropenem, tobramycin, and levofloxacin. The resistance rate of E. coli against carbapenems remained low, and the isolation rate of MRSA was relatively stable during the 10 years. A. baumannii infection led to a high 30-day mortality.
Electronic Supplementary Material
Below is the link to the electronic supplementary material.
Acknowledgements
Not applicable.
Abbreviations
- BSIs
bloodstream infections
- CoNS
Coagulase-negative staphylococci (CoNS)
- MALDI-TOF
Matrix-assisted laser desorption/ionization time-of-flight
- MS
Mass spectrometry
- CLSI
Clinical and Laboratory Standards Institute
- FDA
Food and Drug Administration
- LLA
Linear-by-linear association
- ICU
Intensive care unit
- SXT
Trimethoprim/sulfamethoxazole
- TZP
Piperacillin/tazobactam
- CRKP
Carbapenem-resistant K. pneumoniae
- CRAB
Carbapenem-resistant A. baumannii
- MRSA
Methicillin-resistant S. aureus
- CR
Carbapenem resistance
- CHINET
China Antimicrobial Surveillance Network
- MDR
Multidrug resistance
Author contributions
Weiwei Liu instructed the study, Jia Chen and Guanyi Zhang contributed to data collection, data analysis and writing, Xin Zheng analyzed data.
Funding
This research was supported by Youth talent training program of Longhua Hospital, Shanghai University of Traditional Chinese Medicine (No. XH40204-20250471). This was also supported by Science and Technology Development Project of Shanghai University of Traditional Chinese Medicine (No. 25KFL69).
Data availability
The data and materials supporting the findings of this study are available from the corresponding author upon reasonable request.
Declarations
Ethical approval
This retrospective study was approved by the Medical Research Ethics Committee of Longhua Hospital (No. 2024LCSY156), and was conducted in accordance with the principles of the Declaration of Helsinki. Individual data were collected anonymously and the requirement to obtain informed written consent was waived.
Consent for publication
Not applicable.
Competing interests
The authors declare no competing interests.
Footnotes
Publisher’s note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Jia Chen and Guanyi Zhang contributed equally to this work.
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Supplementary Materials
Data Availability Statement
The data and materials supporting the findings of this study are available from the corresponding author upon reasonable request.