Inducible beta-lactam resistance in Aeromonas hydrophila: therapeutic challenge for antimicrobial therapy.
Despite the abundant amount of knowledge about inducible chromosomally mediated beta-lactamases among Aeromonas species, extended-spectrum beta-lactam-resistant A. hydrophila strains selected in clinical practice were rarely reported. In the present study, two strains of A. hydrophila, A136 and A139, with markedly different susceptibilities to extended-spectrum cephalosporins were isolated from blood and the tip segment of an arterial catheter of a burn patient. Another strain (A136m) was selected in vitro by culturing A136 in a subinhibitory concentration of cefotaxime, the beta-lactam agent administered for the treatment of Aeromonas bacteremia in this patient. Typing studies by arbitrarily primed PCR and pulsed-field gel electrophoresis indicated a clonal relationship among strains A136, A136m, and A139. These strains were identified to be of DNA hybridization group 1. Wild-type strain A136 was resistant only to ampicillin and cephamycins, but A136m and A139 were highly resistant to the expanded- and broad-spectrum cephalosporins. The presence of increased beta-lactamase activity in A139 suggests that A139 is a derepressed mutant which overexpresses beta-lactamases. These results call attention to the use of beta-lactam agents for the treatment of invasive Aeromonas infections.
Departments of Internal Medicine, National Cheng Kung University Hospital, National Cheng Kung University Medical College, Tainan, Taiwan.
W C
WC
Ko
H M
HM
Wu
T C
TC
Chang
J J
JJ
Yan
J J
JJ
Wu
D016980:Aeromonas hydrophila / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics; D016470:Bacteremia / Q000150:complications / Q000188:drug therapy / Q000382:microbiology; D001483:Base Sequence; D002056:Burns / Q000150:complications / Q000601:surgery; D018550:Cephalosporin Resistance / Q000235:genetics; D002511:Cephalosporins / Q000627:therapeutic use*; D003428:Cross Infection / Q000150:complications / Q000188:drug therapy / Q000382:microbiology; D017931:DNA Primers / Q000235:genetics; D004269:DNA, Bacterial / Q000235:genetics / Q000302:isolation & purification; D016521:Electrophoresis, Gel, Pulsed-Field; D005260:Female; D005838:Genotype; D016905:Gram-Negative Bacterial Infections / Q000150:complications / Q000188:drug therapy* / Q000382:microbiology; D006801:Humans; D008875:Middle Aged; D009154:Mutation; D016133:Polymerase Chain Reaction; D013530:Surgical Wound Infection / Q000150:complications / Q000188:drug therapy / Q000382:microbiology; D001618:beta-Lactamases / Q000235:genetics / Q000378:metabolism
D002511:Cephalosporins; D017931:DNA Primers; D004269:DNA, Bacterial; D001618:beta-Lactamases