Prevalence of constitutive and inducible clindamycin resistance among clinical isolates of Staphylococcus aureus in a tertiary care institute in North India

Abstract

Background: Clindamycin is an important drug used in the treatment of Methicillin Sensitive Staphylococcus aureus (MSSA) as well as in Methicillin-resistant Staphylococcus aureus (MRSA) infections. This drug is widely used in the treatment of skin and soft tissue infections caused by them. Therapeutic failure caused by macrolide-lincosamine-streptogramin B constitutive and inducible clindamycin resistance (MLSBc and MLSBi) is being more commonly reported.Methods: The present study was conducted over a period of six months from October 2016 to March 2017 to know the incidence of MLSBc and MLSBi in Staphylococcus aureus (S. aureus) isolates obtained in our hospital by D-test as per CLSI guidelines. A total of 130 isolates of S.aureus were obtained from different clinical specimens which included pus/ wound swab (n=266), urine (n=577), sputum (n=225), blood (n=221), throat swab (n=71), ear/eye discharge (n=21), high vaginal swab (n=20) and body fluids (n=50). All the isolates were subjected to antibiotic sensitivity testing by Kirby Bauer’s disc diffusion method. Amoxyclav, Erythromycin, Clindamycin, Co-trimoxazole, Tetracycline, Ofloxacin, Gentamicin, Linezolid and Vancomycin were the antibiotics used.Results: Out of 130 (8.9%) isolates of S. aureus obtained from 1451 clinical samples, 82 (63.1%) were found to be MSSA and 48 (36.9%) were MRSA. Among S. aureus, 43 (33.1%) isolates showed MLSBc resistance, 22 (16.9%) isolates showed MLSBi resistance and 20 (15.4%) isolates showed MS phenotype. The remaining 45 (34.6%) isolates remained sensitive to Erythromycin. Among MSSA, MLSBc were observed in 18 (22%) isolates and MLSBi in 9 (11%) while in MRSA, MLSBc were observed in 25 (52.1%) isolates and MLSBi in 13 (27.1%) isolates. Almost all clinical isolates showed 100% sensitivity to Vancomycin and Linezolid in routine antibiotic susceptibility testing. Both MLSBc and MLSBi resistance was significantly higher (p<0.05) in MRSA than in MSSA.Conclusions: The study emphasizes the importance of conducting D test along with routine antibiotic susceptibility testing for better utilization of clindamycin in S. aureus infections.

Incidence of Inducible Clindamycin Resistance in Clinical Isolates of Staphylococci and Their Antibiotic Sensitivity Pattern

“…AST pattern for MRSA isolates is shows the best sensitivity for linezolid of 83.54 %, followed by Gentamycin 72.15 %. A 100% sensitivity for linezolid was reported by Shetty J et al, Bansal et al29,30 Hatkar et al has reported a sensitivity of 73.86 % 31. Pai et al has reported a sensitivity of about 40% for gentamycin, which is less as compared to our study.…”

Phenotypic Detection of Inducible Clindamycin Resistance among Clinical Isolates of Staphylococcus aureus in Bharatpur Hospital

“…19 Another study from North India showed 16.9% iMLSB phenotype whereas cMLSB phenotype was 33.1%, much higher than our study. 6 Among 35 MRSA isolates, 34% showed iMLSB phenotype whereas only 6% showed cMLSB phenotype and 60% showed MS phenotype. Other studies such as one in India showed 32% iMLSB phenotype and36% MSSA phenotype among the MRSA isolates.…”

“…15 In another similar study in North India, growth rate was found to be 8.9%. 6 The variation in isolation of S. aureus among different studies could be due to many factors like differences in personal hygiene, lifestyle, population characteristics, direct skin to skin contact, crowded living environment, hospitalization, sharing of individual objects, etc. 16 In the current study, majority of the isolates were recovered from females (74.1%).…”

“…4,5 Clindamycin is mostly used in the treatment of MRSA but can also be used in the case of MSSA infections. 6 Clindamycin, a semisynthetic drug and protein synthesis inhibitor, developed in 1966, is capable of decreasing toxin production and increase microbial opsonization and phagocytosis at subinhibitory concentrations. It is used in treatment of skin and soft tissue infections, abscesses, decubitus ulcers, osteomyelitis, head and neck, pleuropulmonary, abdominal and pelvic infections besides being an alternative in penicillin allergic patients.…”

“…It is used in treatment of skin and soft tissue infections, abscesses, decubitus ulcers, osteomyelitis, head and neck, pleuropulmonary, abdominal and pelvic infections besides being an alternative in penicillin allergic patients. 6,7 Macrolide resistance in S. aureus occurs due to active efflux mechanism coded by mecA gene which confers resistance to macrolide and streptogramins type B (MLSB) or due to erm genes which encode enzymes capable of conferring inducible (iMLSB) or constitutive (cMLSB) resistance to all the three group of drugs via methylation of the 23S rRNA. 8 Clindamycin suppresses production of Panton-Valentine leucocidin and other virulence factors in MRSA.…”