Prevalence and mechanisms of linezolid resistance among staphylococcal clinical isolates from Egypt

AbstractThe emergence of methicillin-resistant staphylococci necessitated the search for alternative agents as linezolid, introduced to treat infections due to multidrug-resistant bacteria. Linezolid resistance has since emerged, yet its global prevalence remains low. In Egypt, little is known about the situation. We investigated the prevalence and mechanisms of resistance among Egyptian staphylococcal clinical isolates. Linezolid resistance among 232 staphylococcal isolates obtained from Alexandria Main Hospitals between 2011 and 2016 was assessed using disc diffusion and minimum inhibitory concentration. Resistant isolates were checked forcfr presence using polymerase chain reaction. The V domain of different alleles of 23S rRNA gene was investigated for mutations. Selection for linezolid-resistant mutants was performed in vitro through serial passages in linezolid sub-inhibitory concentrations. Combinations of linezolid with imipenem or anti-inflammatory agents were investigated using time-kill and modified checkerboard assays. ThreeStaphylococcus haemolyticus isolates (1.3%) from 2015 to 2016 were linezolid-resistant. One isolate carriedcfr which was plasmid-borne, and together with another isolate which had a G2603T point mutation in the V domain of 23S rRNA gene. Successive exposure to linezolid sub-inhibitory concentrations was selected for three resistantStaphylococcus aureus mutants out of ten susceptible isolates. These mutants were more resistant towards different ...
Source: European Journal of Clinical Microbiology and Infectious Diseases - Category: Microbiology Source Type: research