Figure 1Resistance percent of isolates to the 21 antibiotics used in this study. AK = amikacin; AMO–CLA = amoxicillin–clavulanic acid; AZ = aztreonam; CAZ = ceftazidime; CIP = ciprofloxacin; CMD = cefamandole; COL = colistin; CRO = ceftriaxone; CT = cefotetan; CTX = cefotaxime; E = erythromycin; FEP = cefepime; FOX = cefoxitin; GM = gentamicin; IMI = imipenem; LEV = levofloxacin; MEM = meropenem; PT = piperacillin–tazobactam; RIP = rifampicin; T = tetracycline; TS = trimethoprim/sulfamethoxazole.
Figure 2Results of the phenotypic methods for detection of plasmid-mediated AmpC and carbapenemase enzymes in Klebsiella pneumoniae isolates. (A) MBL-positive isolate, (B) AmpC Etest, inconclusive result in isolate, (C) cephamycin Hodge test (CHT), AmpC-negative and AmpC-positive isolates, (D) modified Hodge test (MHT), (E and F) AmpC-negative and AmpC-positive isolates, (G) a positive result obtained from blaGES using the imipenem + boronic acid disk test (top) and a positive result obtained from AmpC using the cefoxitin + boronic acid disk test (bottom), (H) cefoxitin + boronic acid disk test (positive isolate), (I) positive result obtained from MBL-producer isolate using the EDTA disk synergy (EDS) test. BA = boronic acid; CHT = cephamycin Hodge test; FOX = cefoxitin; IMI = imipenem; MBL = metallo-β-lactamase; MHT = modified Hodge test; Ne = negative; Po = positive.
Table 1Characteristics of the 19 AmpC-positive isolates in this study.a
No. of isolates |
AmpC group |
Cephalosporin phenotype
|
AmpC disk test |
Cephamycin Hodge test |
AmpC Etest |
Cefoxitin/cefoxitin+ boronic acid |
CAZ |
CTX |
FOX |
CT |
FEP |
5 |
CIT |
S |
S |
S |
S |
S |
− |
− |
− |
+ |
7 |
CIT |
S |
S |
S |
S |
S |
− |
− |
− |
+ |
9 |
MOX |
R |
R |
R |
R |
R |
− |
− |
IR |
+ |
11 |
MOX |
R |
R |
R |
R |
R |
+ |
− |
IR |
+ |
12 |
MOX |
R |
R |
R |
R |
R |
− |
− |
IR |
+ |
17 |
MOX |
R |
R |
R |
R |
R |
− |
− |
+ |
+ |
1 |
MOX |
R |
R |
S |
S |
R |
− |
− |
− |
+ |
21 |
MOX |
S |
S |
S |
S |
S |
− |
− |
− |
+ |
22 |
MOX |
R |
R |
R |
S |
S |
+ |
+ |
− |
+ |
3 |
DHA |
R |
R |
R |
R |
S |
+ |
− |
IR |
+ |
6 |
EBC |
S |
S |
S |
S |
S |
− |
− |
− |
+ |
51 |
EBC |
R |
R |
S |
S |
R |
− |
− |
− |
+ |
49 |
CIT |
R |
R |
S |
S |
R |
− |
− |
− |
+ |
55 |
CIT |
R |
R |
R |
R |
R |
+ |
+ |
IR |
+ |
60 |
CIT |
R |
R |
R |
S |
R |
+ |
+ |
− |
+ |
68 |
CIT |
R |
R |
R |
R |
R |
− |
− |
IR |
+ |
75 |
CIT |
R |
R |
R |
R |
S |
+ |
+ |
IR |
+ |
89 |
CIT |
R |
R |
R |
R |
R |
− |
− |
IR |
+ |
27 |
EBC |
R |
R |
R |
R |
S |
+ |
+ |
+ |
+ |
Table 2Characteristics of 12 carbapenemase-positive isolates in this study.
Isolates |
Carbapenem phenotype
|
β-Lactamases |
IMI/IMI +boronic acid |
MHT |
IMI/IMI+ EDTA |
CAZ/CAZ+ EDTA |
MBL Etest |
IMI |
MEM |
15 |
R |
R |
VIM |
+ |
− |
+ |
+ |
+ |
18 |
R |
R |
VIM |
+ |
+ |
+ |
+ |
+ |
20 |
R |
R |
VIM |
− |
− |
+ |
+ |
+ |
39 |
S |
R |
VIM |
+ |
+a
|
− |
+ |
+ |
43 |
S |
R |
VIM |
− |
− |
− |
+ |
+ |
47 |
S |
R |
VIM |
− |
− |
− |
+ |
+ |
55 |
R |
R |
VIM and CIT |
+ |
+ |
− |
− |
− |
69 |
S |
R |
VIM |
+ |
+ |
− |
+ |
+ |
70 |
R |
R |
VIM |
+ |
+ |
− |
+ |
+ |
74 |
R |
R |
VIM |
+ |
+ |
− |
+ |
+ |
23 |
R |
R |
GES |
+ |
+ |
+ |
+ |
− |
73 |
R |
R |
GES |
+ |
+ |
+ |
+ |
− |