Molecular epidemiology and characterization of plasmid-encoded beta-lactamases produced by Tunisian clinical isolates of Salmonella enterica serotype Mbandaka resistant to broad-spectrum cephalosporins.
We studied 31 clinical isolates of Salmonella enterica serotype Mbandaka resistant to broad-spectrum cephalosporins and recovered in Tunisia over a 5-year period. The transferability of this resistance was demonstrated by conjugation experiments. Thirty of the 31 isolates were positive in the double-disk synergy test. By isoelectric focusing analysis, all of the isolates were found to produce a band of beta-lactamase activity with a pI of 5.9. Three of these isolates produced an additional band with a pI of 7.6. PCR and DNA sequencing identified these beta-lactamases as TEM-4 and SHV-2a, respectively. The remaining isolate, highly resistant to ceftazidime but susceptible to cefepime, produced a beta-lactamase that focused at pI 7.8. No synergy was detected by the double-disk synergy test. Sequence analysis of the bla gene amplified by PCR showed that the plasmid-mediated AmpC-type enzyme was ACC-1a. Fingerprinting analysis by repetitive-element PCR and enterobacterial repeat intergenic consensus-PCR suggested that 29 of the 31 Salmonella serotype Mbandaka isolates belonged to the same clonal population.
Makanera
Abdoulaye
A
Laboratoire de Biochimie et Biologie Moléculaire, Faculté des Sciences de Tunis, Département de Biologie, Université de Tunis El Manar, 2092 Tunis, Tunisia.
Arlet
Guillaume
G
Gautier
Valérie
V
Manai
Mohamed
M
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002511:Cephalosporins / Q000494:pharmacology*; D003227:Conjugation, Genetic; D016172:DNA Fingerprinting / Q000379:methods; D008826:Microbial Sensitivity Tests; D017720:Molecular Epidemiology; D010957:Plasmids / Q000235:genetics; D016133:Polymerase Chain Reaction; D012480:Salmonella Infections / Q000453:epidemiology / Q000382:microbiology*; D019779:Salmonella enterica / Q000145:classification / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics; D012703:Serotyping; D018440:beta-Lactam Resistance; D001618:beta-Lactamases / Q000235:genetics* / Q000378:metabolism
D000900:Anti-Bacterial Agents; D002511:Cephalosporins; C062760:beta-lactamase SHV-2; C061036:beta-lactamase TEM-4; D001618:beta-Lactamases