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In vitro susceptibility of Actinobaculum schaalii to mecillinam

2011; Oxford University Press; Volume: 66; Issue: 9 Linguagem: Inglês

10.1093/jac/dkr270

1460-2091

P. Andersen, Karen Marie Søby, Steffen Bank, J. Prag,

Diphtheria, Corynebacterium, and Tetanus

Twenty-two out of these 50 ESBL-producing Salmonella isolates showed variable levels of resistance to the aminoglycosides tested (gentamicin, kanamycin and streptomycin) and were screened for detection of the armA methylase gene by PCR, as described by Gonzalez-Zorn et al. 7 The armA gene was detected in the isolates showing high-level resistance (no inhibition zone) to all of the aminoglycosides tested: Salmonella Typhimurium (n¼13); and Salmonella 4,12:-:1,2 (n¼1).The armA gene was also detected in four isolates of Salmonella Enteritidis displaying high-level resistance to gentamicin and kanamycin but susceptibility to streptomycin.No armA gene was detected among the four isolates displaying high-level resistance to gentamicin and streptomycin but susceptibility to kanamycin.Sequencing of the bla CTX-M genes from the 18 armA-positive isolates allowed identification of the CTX-M-15 determinant.Moreover, 13 of them co-produced CMY-2 (Table 1).The conjugal transfer of the 16S rRNA methylase and ESBL determinants was performed with Escherichia coli J53 and nalidixic acid-resistant E. coli JM109 as recipient strains.Selection of the transconjugants was performed on agar plates containing 100 mg/L sodium azide supplemented with 50 mg/L amoxicillin, and on agar plates supplemented with 30 mg/L amikacin and 30 mg/L gentamicin.In each experiment, no strain highly resistant to aminoglycosides and to b-lactams was recovered after this selection.The genetic diversity of the armA-positive isolates was analysed by PFGE using the standardized PulseNet protocol. 8PFGE analysis of 12 armA-positive isolates of Salmonella Typhimurium revealed an identical pattern, suggesting the spread of an epidemic clone.The four armA-positive Salmonella Enteritidis isolates displayed three distinct PFGE patterns, most likely indicating horizontal spread of the resistance determinants (Table 1).So far, enterobacterial isolates co-harbouring the bla CTX-M-15 and armA genes have been identified as Klebsiella pneumoniae, Klebsiella oxytoca and E. coli. 5,9,10Interestingly, in the study by Bogaerts et al., 5 the patients seemed to have been transferred from Algeria.We report here the concomitant occurrence of these two genes among ESBL-producing S. enterica isolates that have been recovered in Algeria.In that country, the armA gene had been previously identified among CTX-M-3-producing S. enterica serotype Senftenberg isolates. 4 The emergence of the armA methylase gene among CTX-M-15 ESBL-harbouring strains of S. enterica is a public health concern in Algeria.It certainly requires the implementation of a strict hospital infection control policy as well as the promotion of epidemiological surveys in the community in order to avoid the dissemination of such multiresistant strains.