Imipenem Resistance in Salmonella enterica Serovar Wien Related to Porin Loss and CMY-4 β-Lactamase Production

Two multidrug-resistant Salmonella enterica serovar Wien strains (SW468 and SW1107) were isolated in 2001 in Tunis. Both strains produced the β-lactamases TEM-1, SHV-2a, and CMY-4, whereas strain SW1107 also produced the β-lactamase CTX-M-3. The imipenem-resistant strain (SW468) was totally devoid of the OmpF-immunorelated porin. Imipenem resistance was shown as being related to porin loss and CMY-4 β-lactamase production

Clonal lineages detected amongst tetracyclineresistant meticillin-resistant Staphylococcus aureus isolates of a Tunisian hospital, with detection of lineage ST398

Tetracycline resistance has been postulated as a potential phenotypic marker of livestockassociated lineage ST398 amongst meticillin-resistant Staphylococcus aureus (MRSA) clinical isolates in some European hospitals. The objective of this study was to determine if this marker could also be applied to Maghrebian countries. In total, 99 MRSA isolates were collected in a Tunisian hospital during January 2011October 2012, and 24 tetracycline-resistant MRSA isolates of this collection were characterized. All isolates were tested for antimicrobial resistance phenotypes and genotypes, molecular typing, and virulence genes. Multilocus sequence typing showed that the majority of the isolates (19/24) belonged to clonal complex CC8 (ST247, n512 isolates; ST239, n56isolates; ST241, n51 isolate). The remaining isolates belonged to CC398 (ST398, n51 isolate), CC5 (ST5 and ST641, n52 isolates), and CC80 (ST728, n52 isolates). Spa typing discriminated MRSA in eight spa types: t052 (n512 isolates), t037 (n55 isolates), t044 (n52 isolates), and t899, t129, t311, t1744 and the new t14712 (n51 isolate each). Three agr groups were found amongst the studied isolates: agr group I (n520 isolates), agr group II (n52) and agr group III (n52 isolates). We report the detection of one MRSA ST398t899 isolate in the nasal sample of a farmer patient in Tunisia, representing the first report of ST398 in humans in Africa. Tetracycline resistance seems not to be a good phenotypic marker for MRSA ST398 strains in Tunisia, where CC8 was the most prevalent lineage. Continuous efforts to understand the changing epidemiology of this micro-organism are necessary not only for appropriate antimicrobial treatment and effective infection control, but also to monitor its evolution. © 2015 The Authors