Table 2.
Characteristics of Colonizing Fluoroquinolone-Resistant Enterobacterales Isolates Prior to Transplant
| Organism Type | No. (% of Total of 56 Isolates) |
|---|---|
| Species and most common MLST | |
| Escherichia coli | 51 (89) |
| ST131 | 23 |
| ST1193 | 9 |
| Klebsiella pneumoniae | 3 (5) |
| Citrobacter freundii | 1 (2) |
| Enterobacter cloacae | 1 (2) |
| Antimicrobial susceptibilities, % susceptible | |
| Amikacin | 100 |
| Amoxicillin-clavulanate | 70 |
| Ampicillin-sulbactam | 34 |
| Ampicillin | 16 |
| Aztreonam | 68 |
| Cefazolin | 34 |
| Cefepime | 70 |
| Cefoxitin | 88 |
| Ceftazidime | 71 |
| Ceftriaxone | 66 |
| Cefuroxime | 59 |
| Ciprofloxacin | 0 |
| Ertapenem | 100 |
| Gentamicin | 79 |
| Levofloxacin | 5 |
| Meropenem | 100 |
| Piperacillin-tazobactam | 100 |
| Tobramycin | 75 |
| Trimethoprim-sulfamethoxazole | 36 |
| Fluoroquinolone resistance determinantsa | |
| Chromosomal mutations | |
| gyrA mutations | 48 (87) |
| Mutation at codon 83 | 48 (87) |
| Mutation at codon 87 | 47 (86) |
| parC mutations | 50 (91) |
| Mutation at codon 80 | 49 (89) |
| Mutation at codon 84 | 21 (38) |
| parE mutations | 41 (75) |
| 5 chromosomal mutations | 20 (36) |
| 4 chromosomal mutations | 22 (40) |
| 3 chromosomal mutations | 5 (9) |
| 2 chromosomal mutations | 1 (2) |
| 1 chromosomal mutations | 2 (4) |
| No chromosomal mutations | 5 (9) |
| Plasmid-mediated resistance determinants | |
| Qnr | 9 (16) |
| aac(6’)-Ib-cr | 4 (7) |
| Oqx b | 2 (4) |
| Notable β-lactamase genesa | |
| ESBL genes: blaCTX-Mc,d | 14 (25) |
| AmpC-encoding genese | 4 (7) |
| Narrow-spectrum β-lactamase genes | 33 (60) |
| bla TEM-1 | 28 (51) |
| blaSHV-1 or blaSHV-11 | 2 (4) |
| bla OXA-1 | 4 (7) |
Abbreviations: ESBL, extended-spectrum β-lactamase; MLST, multilocus sequence type; ST, sequence type.
aThe genetic characterizations are based on 55 isolates that underwent whole-genome sequencing.
bThree additional Klebsiella pneumoniae strains harbored chromosomal oqxA genes, but these genes do not confer fluoroquinolone resistance in K. pneumoniae.
cTwo strains tested positive for ESBL production by phenotypic testing, but no ESBL-encoding genes were identified by sequencing. blaCTX-M was the only type of ESBL gene identified.
dThe most common CTX-M variants were CTX-M-27 (n = 9), CTX-M-15 (n = 3), CTX-M-14 (n = 1), and CTX-M-55 (n = 1).
eThe most common AmpC-encoding genes were blaCMY-2 (n = 2), blaCMY-55 and blaDHA-1 (n = 1), and blaACT-17 (n = 1).