Rifampicin resistance among multi-resistant MRSA clinical isolates from Chennai, India, and their molecular characterization

Abstract

ABSTRACT. High-level methicillin-resistant Staphylococcus aureus (MRSA) isolates show rapid evolution of rifampicin resistance, forcing reliance upon expensive and often inferior antibiotics to manage these infections. Accordingly, this study was conducted to: 1) evaluate the level of multidrug resistance among hospital-associated MRSA isolates from Chennai, India; 2) determine their rifampicin resistance and molecular characterization; and 3) analyze the identified rpoB gene mutations for predominant high-level rifampicin resistanceassociated nucleotide changes. Conventional laboratory techniques and antibiogram evaluation by disc diffusion were utilized for isolate phenotypic identification. Among the 54 isolates obtained, 74% (42) were found to be MRSA. All the isolates exhibited complete susceptibility to linezolid and vancomycin, and variable resistance to conventional antibiotics; the MAR index value calculated was 0.64. Genotypic identification of the high-level rifampicin-resistant isolate S. aureus KM05 was established through rpoB amplification and 2717 Rifampicin-resistant MRSA isolates from Chennai, India ©FUNPEC-RP www.funpecrp.com.br Genetics and Molecular Research 14 (1): 2716-2725 (2015) sequencing. The evolutionary relationship of KM05 to other isolates and its rpoB gene mutation status was determined to understand the genetic basis of its high rifampicin resistance. The S. aureus KM05 rpoB gene yielded ≥98% sequence similarity and a close phylogenetic relationship with other known reference database organisms. It also showed mutational changes in three rpoB codon positions encoding amino acids at positions 455, 481, and 529. These results have established the prevalence of rifampicin resistance among Chennai hospital MRSA isolates, and suggest that the predominant high-level resistance nucleotide changes would serve to form a basis for their diagnosis and control of rifampicin-resistant MRSA.

A Prospective Observational Study of Antibiotic Usage Patterns and Microbiological Analysis in Diabetic Foot Ulcer Patients

“…A study conducted by Umadevi et al, reported that Amikacin, Piperacillin/tazobactum and Imipenem were sensitive against Gram negative bacteria [24]. This present scenario distinguished from a study in Chennai that they reported E.Coli showed 100% sensitivity to Imipenem and Meropenem and they are resistant against Gentamycin [25]. Our study reported that E.Coli exhibited (83%) sensitivity to Clotimaxazole, (75%) to Meropenem and (33%) to Imipenem.…”

Egyptian fennel honey and/or propolis against MRSA harboring both mecA & icaAgenes

“…Figure 2 and the overall MAR index of tested strains was 0.48±0.12 (Figure 3). The tested MRSA strains had very high MAR index value since MAR index value just≥0.2, is considered high 40 and might be originated from environments with misuse of antibiotics where resistance developed and spread, 43 rather than harboring both mecA & icaA genes (Figure 4). All tested MRSA strains showed positive congo red testing concluding that these tested strains were biofilm producing MRSA pheno as well as genotypically.…”

Nasal Methicillin-resistant Staphylococcus aureus carriage and related risk factors in university student population

“…Previous studies with similar sample populations reported increased resistance rates of MRSA isolates to erythromycin, tetracycline [5,25,26] . However, resistance to rifampicin and kanamycin is observed in clinical MRSA isolates mostly isolated from hospitalized patients [27,28] . The reason may be the excessive use of such antibiotics in our sample population because they are still easily accessible in our country.…”