TABLE 2.
Results of the modified Hodge test and the Triton Hodge test and carbapenem susceptibility of selected carbapenemase-producing and nonproducing clinical isolates
| Group and β-lactamase | Bacterial species | % of resistance (% of nonsusceptibility)a to: |
No. (%) positive |
|||||
|---|---|---|---|---|---|---|---|---|
| MHT |
THT |
|||||||
| IMP | MEM | ERT | MEM | ERT | MEM | ERT | ||
| MBLs (n = 60) | ||||||||
| Enterobacteriaceae (n = 33) | ||||||||
| IMP-8 (n = 15) | C. freundii (n = 1), E. coli (n = 2), Enterobacter asburiae (n = 1), E. cloacae (n = 7), Klebsiella oxytoca (n = 1), K. pneumoniae (n = 2), S. marcescens (n = 1) | 27 (75) | 27 (75) | 33 (87.5) | 15 (100) | 15 (100) | 15 (100) | 15 (100) |
| VIM-1 (n = 1) | E. coli (n = 1) | 100 | 100 | 100 | 1 (100) | 1 (100) | 1 (100) | 1 (100) |
| VIM-2 (n = 16) | E. cloacae (n = 6), K. pneumoniae (n = 2), P. rettgeri (n = 4), P. stuartii (n = 4) | 68.8 (81.3) | 81.3 (81.3) | 81.3 (100) | 16 (100) | 16 (100) | 16 (100) | 16 (100) |
| VIM-11 (n = 1) | E. cloacae (n = 1) | 0 (0) | 0 (0) | 100 | 1 (100) | 1 (100) | 1 (100) | 1 (100) |
| All Enterobacteriaceae | 33 (100) | 33 (100) | 33 (100) | 33 (100) | ||||
| Non-Enterobacteriaceae (n = 27) | ||||||||
| IMP-1 (n = 4) | Acinetobacter junii (n = 2), Acinetobacter ursingii (n = 2) | 100 | 100 | ND | 4 (100) | 4 (100) | 4 (100) | 4 (100) |
| IMP-13 (n = 4) | P. aeruginosa (n = 4) | 50 (50) | 50 (50) | ND | 2 (50) (uninterp, 2) | 2 (50) (uninterp, 2) | 3 (75) (uninterp, 1) | 3 (75) (uninterp, 1) |
| IMP-16 (n = 4) | P. aeruginosa (n = 4) | 100 | 100 | ND | 2 (50) (uninterp, 2) | 2 (50) (uninterp, 2) | 4 (100) | 4 (100) |
| IMP-18 (n = 1) | P. aeruginosa (n = 1) | 100 | 100 | ND | 0 (0) (uninterp, 1) | 0 (0) (uninterp, 1) | 1 (100) | 0 (0) (uninterp, 1) |
| VIM-2 (n = 11) | P. aeruginosa (n = 5), Pseudomonas chlororaphis (n = 1), Pseudomonas fulva (n = 1), Pseudomonas monteili (n = 1), Pseudomonas oleovorans (n = 1), Pseudomonas putida (n = 2) | 100 | 100 | ND | 2 (18) (uninterp, 5)b | 5 (45) (uninterp, 5)b | 11 (100) | 11 (100) |
| VIM-11 (n = 1) | P. aeruginosa (n = 1) | 100 | 100 | ND | 0 (0) (uninterp, 1) | 0 (0) (uninterp, 1) | 1 (100) | 1 (100) |
| SPM-1 (n = 2) | P. aeruginosa (n = 2) | 100 | 100 | ND | 2 (100) | 2 (100) | 2 (100) | 2 (100) |
| All non-Enterobacteriaceae | 12 (44) | 15 (56) | 26 (96) | 25 (93) | ||||
| All MBLs (n = 60) | 45 (75) | 48 (80) | 59 (98) | 58 (97) | ||||
| Class A carbapenemases (n = 25) | ||||||||
| Enterobacteriaceae (n = 19) | ||||||||
| KPC-2 (n = 14) | Citrobacter braakii (n = 1), C. freundii (n = 1), E. coli (n = 3), E. cloacae (n = 2), Leclercia adecarboxylata (n = 1), K. oxytoca (n = 1), K. pneumoniae (n = 5) | 50 (85.7) | 50 (71.4) | 64.2 (85.7) | 14 (100) | 14 (100) | 14 (100) | 14 (100) |
| KPC-3 (n = 1) | K. pneumoniae (n = 1) | 100 | 100 | 100 | 1 (100) | 1 (100) | 1 (100) | 1 (100) |
| GES-3 (n = 1) | K. pneumoniae (n = 1) | 100 | 100 | 100 | 1 (100) | 1 (100) | 1 (100) | 1 (100) |
| NMC-A (n = 1) | E. cloacae (n = 1) | 100 | 100 | 100 | 1 (100) | 1 (100) | 1 (100) | 1 (100) |
| SME-1b (n = 2) | S. marcescens (n = 2) | 100 | 50 (50) | 0 (0) | 1 (50) (uninterp, 1) | 1 (50) (uninterp, 1) | 2 (100) | 2 (100) |
| All Enterobacteriaceae | 18 (95) | 18 (95) | 19 (100) | 19 (100) | ||||
| Non-Enterobacteriaceae (n = 6) | ||||||||
| KPC-2 (n = 5) | P. aeruginosa (n = 5) | 100 | 100 | ND | 5 (100) | 5 (100) | 5 (100) | 5 (100) |
| GES-5 (n = 1) | P. aeruginosa (n = 1) | 100 | 100 | ND | 1 (100) | 1 (100) | 1 (100) | 1 (100) |
| All non-Enterobacteriaceae | 6 (100) | 6 (100) | 6 (100) | 6 (100) | ||||
| All class A carbapenemases (n = 25) | 24 (96) | 24 (96) | 25 (100) | 25 (100) | ||||
| Class D carbapenemases (n = 20) | ||||||||
| OXA-48 (n = 5) | E. coli (n = 3), K. oxytoca (n = 1), K. pneumoniae (n = 1) | 20 (80) | 40 (100) | 80 (100) | 5 (100) | 5 (100) | 5 (100) | 5 (100) |
| OXA-163 (n = 11) | C. freundii (n = 1), E. cloacae (n = 3), E. coli (n = 2), K. pneumoniae (n = 3), P. stuartii (n = 2) | 18.1 (27.3) | 27.3 (27.3) | 100 | 11 (100) | 11 (100) | 11 (100) | 11 (100) |
| OXA-181 (n = 1) | K. pneumoniae (n = 1) | 100 | 100 | 100 | 1 (100) | 1 (100) | 1 (100) | 1 (100) |
| OXA-247 (n = 2) | E. coli (n = 1), K. pneumoniae (n = 1) | 50 (100) | 50 (100) | 50 (100) | 2 (100) | 2 (100) | 2 (100) | 2 (100) |
| OXA-438 (n = 1) | E. coli (n = 1) | 100 | 100 | 100 | 1 (100) | 1 (100) | 1 (100) | 1 (100) |
| All class D carbapenemases (n = 20) | 20 (100) | 20 (100) | 20 (100) | 20 (100) | ||||
| Carbapenemase nonproducers (n = 40) | ||||||||
| ESBLs + porin loss (n = 20)c | E. aerogenes (n = 1), E. cloacae (n = 2), K. pneumoniae (n = 16), S. marcescens (n = 1) | 10 (50) | 85 (90) | 95 (100) | 1 (5) | 2 (10) | 2 (10) | 3 (15) |
| Overexpression of chromosomal AmpC + porin loss (n = 18) | E. aerogenes (n = 2), E. cloacae (n = 14), E. coli (n = 2) | 61.1 (100) | 44.4 (88.9) | 100 | 1 (6) | 1 (6) | 1 (6) | 2 (11) |
| CMY-2 (n = 2) | E. coli (n = 1), K. pneumoniae (n = 1) | 0 (0) | 0 (0) | 0 (0) | 0 (0) | 0 (0) | 0 (0) | 0 (0) |
| All nonproducers (n = 40) | 2 (5) | 3 (7.5) | 3 (7.5) | 5 (12.5) | ||||
a
Intermediate plus resistant isolates for the indicated carbapenem (when applied). IMP, imipenem; MEM, meropenem; ERT, ertapenem; ND, not determined; uninterp, uninterpretable test due to inhibition of growth of the indicator strain along the tested isolate.
b
Four isolates of P. aeruginosa and one isolate of P. putida producing VIM-2 with uninterpretable results.
c
The ESBLs included were CTX-M-2 (n = 16) and CTX-M-15 (n = 4).