Open access articles
The seasonal variation of infectious diseases is an important factor in the diagnosis of a disease. In this study, Ramsey et al. have retrospectively evaluated the seasonality of antimicrobial resistance rates of community-acquired E. coli bloodstream isolates to various agents in Richland county, South Carolina, USA and evaluate seasonality of multi-drug resistant E. coli and its association with antimicrobial consumption in the community. Summer months were independently associated with a decrease in antimicrobial resistance to amoxicillin + clavulanic acid, cefazoline, ceftriaxone and cotrimoxazole, which are antibiotics mostly prescribed for community-acquired infections. Interestingly, there was a significant association between the proportion of community acquired MDR E. coli bloodstream infection and ambulatory antimicrobial consumption in South Carolina. These findings are important to better understand local epidemiology of resistance and maybe to better adapt empirical treatment according to the seasons, for example.
Evidence of a transmission of multi-drug resistant bacteria between animals and human is a challenging question. In this study, Sun et al. explored the prevalence of Methicillin-Resistance Staphylococcus aureus (MRSA) along a food production chain, operation workers, environment and surrounding community in China. The livestock-associated clone MRSA-CC9 was detected from commercial farm and slaughterhouse, but its presence decreased along the chain and was not found in the surrounding community and villages. In humans, the clone MRSA ST59-t437 commonly found in the community was identified. However, the ST398 MSSA was identified both in human and pigs but belong to two different populations. This study shows how the spread of a clone is limited here to its direct environment (i.e. farm, animals, food production chain, operation workers) but does not spread to the surrounding community. Interestingly, the MSSA ST398 clone which is present in both pigs and humans has divided in two populations that evolved separately in their different hosts and did not mix.