ampc β-lactamases in urinary klebsiella pneumoniae isolates: first report of acc type ampc β-lactamase resistance in iran

Background & objective: the production of plasmid-mediated ampc beta-lactamases (pmabls) among urinary klebsiella pneumoniae isolates causes a severe problem to the successful treatment of urinary tract infections (utis). this study was designed to evaluate antimicrobial resistance, the presence of ampc beta-lactamase genes, and the genetic relatedness among k. pneumoniae strains separated from patients with uti. materials & methods: in this cross-sectional descriptive study, a total of 100 k. pneumoniae isolates were collected from uti cases in milad hospital, tehran, iran. the sensitivity of the isolates to 12 antibiotics was tested using the kirby-bauer disk diffusion method. ampc production was determined using a boronic acid combined-disk test. polymerase chain reaction (pcr) was carried out to screen all isolates with family-specific pmabl genes. the genetic relatedness of ampc-producing isolates was determined by an enterobacterial repetitive intergenic consensus polymerase chain reaction (eric-pcr). results: over a period of 11 months, pmabls were detected in 49 isolates (49%) of k. pneumoniae. resistance to at least three classes of antimicrobials was detected in 30 (61.2%) pmabl producers. among ampc producers, 34 isolates harbored only one ampc gene group, including mox (n=11), ebc (n=8), acc (n=7), cit (n=4), fox (n=2), and dha (n=2). multiple ampc gene groups were detected in 15 isolates. the eric-pcr showed the polyclonal distribution of ampc-producing isolates. conclusion: in our study, a high frequency of ampc-producing k. pneumoniae was observed. this is the first report of acc type ampc beta-lactamase in iran. strategies to minimize the spread of ampc beta-lactamase-producing isolates should be implemented.