Inducible clindamycin resistance among clinical Staphylococcus aureus strains in Iran: A contemporaneous systematic review and meta-analysis

Abstract

Clindamycin has long been considered as an effective alternative drug against Staphylococcus aureus. Strains with inducible clindamycin resistance (iMLSB phenotype) raise concerns because therapeutic failure may occur during the course of treatment. In this systematic review and meta-analysis, we sought to determine the overall prevalence of iMLSB phenotype (D-test positive) among clinical S. aureus strains in Iran during 2015–2020. Furthermore, the percentages of genes conferring resistance to the MLSB antibiotics together with different genetic backgrounds of the iMLSB strains were analyzed. The overall prevalence of iMLSB in Iran was 10.40% (95% CI: 8.25–12.76%), ranging from 1 to 18.75%. These strains are commonly encountered in wound and blood samples. The pooled prevalence of iMLSB in S. aureus was greater than that of methicillin-resistant Staphylococcus aureus (MRSA). Several studies also showed high rates of ermC, while the others reported ermA as the predominant gene among iMLSB strains. Regarding multilocus sequence typing (MLST) and staphylococcal cassette chromosome mec (SCCmec) typing, ST239-MRSA-SCCmec III and ST22-MRSA-SCCmec IV, also known as ERMSA-15, were the most frequent clones. As for S. aureus Protein A (spa) typing, spa types t037 and t021 are predominant ones among MRSA and methicillin-sensitive Staphylococcus aureus (MSSA) strains with iMLSB phenotype, respectively. Accessory gene regulator (agr) group I was shown to be abundant among D-test positive strains. Overall, we found that iMLSB strains are closely linked with certain clonal lineages. There is an urgent need for ongoing and nationwide surveillance studies to further evaluate these strains.