Phenotypic Detection of Macrolide-Lincosamide-Streptogramin Resistance among Staphylococcus aureus and Staphylococcus epidermidis in Baghdad, Iraq

Abstract

Introduction: Staphylococci emerged as the most frequent nosocomial and community-acquired pathogens. Macrolide-lincosamide-streptogramin (MLS) antibiotics resistance was increasing among Staphylococcus aureus and Staphylococcus epidermidis (S. epidermidis) isolates. Objective: In the present study, the aim was to detect the phenotypic resistance pattern of MLS (constitutive and inducible) among S. aureus and S. epidermidis isolated from Iraqi patients. Methods: A total of 120 staphylococcal isolates (60 S. aureus and 60 S. epidermidis) were isolated from urine, wound swab, blood, and sputum specimens, then specified by the VITEK 2 system. Whole isolates were investigated by the disk-diffusion method against many antibiotics, then they were checked for the MLS phenotype by the D-zone test. Results: Out of 60 S. aureus isolates and 60 S. epidermidis, the isolation rates from wound, urine, blood, and sputum were 66.6 and 50%, 16.7 and 26.7%, 11.7 and 18.3%, and 5% for each species, respectively. The higher frequency rates of resistance were showed against erythromycin, clindamycin, and streptomycin, for both S. aureus with 83.3, 53.3, and 83.3%, respectively, and S. epidermidis with 73.3, 45, and 76.7%, respectively. Constitutive MLS resistance phenotype (MLSc) was shown in 32 isolates (53.3%) of S. aureus and inducible MLS resistance phenotype (MLSi) was noted in 16 isolates (26.7%). Conclusion: The current study concluded that the D-zone test must be applied within the routine work of the antimicrobial susceptibility test for staphylococcal isolates, to exclude the false results of staphylococcal isolates sensitivity against clindamycin.