Volume 22, Number 9—September 2016
Dispatch
Multidrug-Resistant Shigella Infections in Patients with Diarrhea, Cambodia, 2014–2015
Table 2
Antimicrobial susceptibility results and molecular characterization of resistance genes of Shigella isolates collected from patients in Cambodia, July 2014–April 2015*
Isolate no. | Organism | Antimicrobial resistance | CIP MIC, µg/mL† | Amino acid substitutions in QRDR |
AZM MIC, µg/mL‡ | mphA gene | ESBL confirmatory test | β-lactamase genes | ||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
gyrA |
parC |
|||||||||||
Ser 83 | Asp 87 | Ser 57 | Ser 80 | |||||||||
1 | S. flexneri 2a | AMP-SXT-TET-NAL | 0.25 | Leu | – | – | – | 2.00 | Neg | Neg | TEM-1, OXA-1 | |
2 | S. flexneri 2a | AMP-SXT-TET-NAL | 0.25 | Leu | – | – | – | 1.50 | Neg | Neg | TEM-1, OXA-1 | |
3 | S. flexneri 2v | AMP-SXT-TET-NAL | 0.19 | Leu | – | – | – | 1.50 | Neg | Neg | TEM-1, OXA-1 | |
4 | S. flexneri 3a | AMP-SXT-TET-NAL | 0.25 | Leu | – | – | – | 1.00 | Neg | Neg | TEM-1 | |
5 | S. flexneri 3a | AMP-SXT-TET-NAL | 0.19 | Leu | – | – | – | 1.50 | Neg | Neg | TEM-1 | |
6 | S. flexneri 3a | AMP-SXT-TET-NAL-CIP | 4.00 | Leu | – | Arg | – | 0.75 | Neg | Neg | TEM-1 | |
7 | S. flexneri 3a | AMP-SXT-TET-NAL-CIP | 4.00 | Leu | – | Arg | – | 1.00 | Neg | Neg | TEM-1 | |
8 | S. flexneri 3a | AMP-SXT-TET-NAL-CIP | 4.00 | Leu | – | Arg | – | 1.00 | Neg | Neg | TEM-1 | |
9 | S. flexneri 3a | AMP-SXT-TET-NAL-CIP-AZM-CRO-CTX | 6.00 | Leu | – | Arg | – | 32.00 | Pos | Pos | TEM-1, CTX-M-27 | |
10 | S. sonnei | AMP-SXT-TET-NAL-CIP-CRO-CTX-CAZ | 6.00 | Leu | Gly | – | Ile | 4.00 | Neg | Pos | CTX-M-55 |
*AMP, ampicillin; Arg, arginine; Asp, aspartate; AZM, azithromycin; CAZ, ceftazidime; CIP; ciprofloxacin; CRO, ceftriaxone; CTX, cefotaxime; ESBL, extended-spectrum β-lactamase; Gly, glycine; Ile, isoleucine; Leu, leucine; NAL, nalidixic acid; Neg, negative; Pos, positive; QRDR, quinolone-resistance determining region; Ser, serine; SXT, trimethoprim/sulfamethoxazole; TET, tetracycline; –, no amino acid substitutions found.
†CIP MIC interpretive criteria for Enterobacteriaceae is susceptible <1, resistant >4 µg/mL.
‡AZM MIC interpretive criteria for Salmonella enterica serovar Typhi is susceptible <16, resistant >32 µg/mL.