Macrolide resistance in Staphylococcus from COVID-19 patients in Santander

Intensive use of macrolides, such as azithromycin, during the COVID-19 pandemic has facilitated the development of antimicrobial resistance in Gram-positive bacteria through multiple resistance mechanisms, including ribosomal RNA modification, efflux pumps, and enzymatic inactivation.

To describe the prevalence of resistance genes in bacteria isolated from COVID-19 patients in Santander, Colombia.

A descriptive study was conducted on 112 stored samples from nasopharyngeal and oropharyngeal swabs and tracheal aspirates collected from hospitalized COVID-19 patients in 2020, from which 48 Gram-positive strains were isolated. Macrolide resistance and the presence of the ermA, ermB, ermT, and mef(A/E) genes were evaluated through phenotypic and molecular tests.

Staphylococcus aureus was the most prevalent species at 58.33% (28), followed by Staphylococcus epidermidis at 31.25% (15). A total of 47.92% (23) of the strains showed phenotypic resistance to azithromycin, and 81.25% (39) displayed genotypic resistance, with ermB being the most prevalent at 58.33% (28) and ermT at 45.83% (22), with no detection of mef(A/E).

These findings reveal a high prevalence of macrolide resistance, which may be related to the extensive use of these antibiotics during the pandemic.

The increase in macrolide resistance among Gram-positive bacteria represents a critical public health challenge, especially in the context of pandemics. These results underscore the urgent need to implement control measures in antibiotic use.