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Prevalence and genotypic relatedness of methicillin resistant Staphylococcus aureus in a tertiary care hospital.
J Postgrad Med. 2014 Oct-Dec; 60(4):386-9.JP

Abstract

BACKGROUND

Methicillin-resistant Staphylococcus aureus (MRSA) is the most common multidrug-resistant pathogen causing nosocomial infections across the world. MRSA is not only associated with significant mortality and morbidity but also places a large economic strain on our health care system. MRSA isolates are also typically resistant to multiple, non-β-lactam antibiotics. We conducted a prospective study in a tertiary care hospital, to determine the prevalence of MRSA and to establish the clonal distribution of MRSA isolates recovered from various clinical specimens.

MATERIALS AND METHODS

Clinical samples were cultured and S. aureus was identified as per standard microbiological procedures. Susceptibility testing was done by agar disk diffusion and minimum inhibitory concentration (MIC) method as recommended by CLSI. Methicillin resistance was detected by phenotypic methods namely, oxacillin disc diffusion (ODD), minimum inhibitory concentration (MIC) of oxacillin, cefoxitin disk diffusion (CDD), and MIC of cefoxitin. Amplification of mecA gene by PCR was used as gold standard for detection of methicillin resistance. Pulsed field gel electrophoresis (PFGE) typing was performed for MRSA isolates.

RESULTS

Out of 390 S. aureus isolates, 154 (39.48%) isolates were MRSA and 236 (60.51%) isolates were MSSA. Penicillin was the least effective antibacterial drug against the hospital associated S. aureus isolates with 85.64% resistance rate. All the isolates were susceptible to vancomycin. The MRSA showed a high level of resistance to all antimicrobials in general in comparison to the MSSA and the difference was statistically significant (P < 0.05). Multiplex PCR performed for all strains showed amplification of both the mecA and nucA genes in MRSA strains whereas MSSA strains showed amplification of only nucA gene. PFGE of these isolates showed 10 different patterns.

CONCLUSION

Prevalence of MRSA in our hospital was 39.48%. Most of these isolates were resistant to erythromycin, clindamycin, cotrimoxazole, and ciprofloxacin, whereas high sensitivity was seen to vancomycin followed by gentamicin. CDD and MIC for cefoxitin showed 100% sensitivity, specificity, PPV and NPV as compared to PCR for mecA gene. In maximum number of isolates PFGE type A pattern was seen suggesting clonal relatedness.

Authors+Show Affiliations

Department of Microbiology, Sher-I-Kashmir Institute of Medical Sciences, Srinagar, Jammu and Kashmir, India.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

25370547

Citation

Fomda, B A., et al. "Prevalence and Genotypic Relatedness of Methicillin Resistant Staphylococcus Aureus in a Tertiary Care Hospital." Journal of Postgraduate Medicine, vol. 60, no. 4, 2014, pp. 386-9.
Fomda BA, Thokar MA, Bashir G, et al. Prevalence and genotypic relatedness of methicillin resistant Staphylococcus aureus in a tertiary care hospital. J Postgrad Med. 2014;60(4):386-9.
Fomda, B. A., Thokar, M. A., Bashir, G., Khan, A., Kour, A., Zahoor, D., & Ray, P. (2014). Prevalence and genotypic relatedness of methicillin resistant Staphylococcus aureus in a tertiary care hospital. Journal of Postgraduate Medicine, 60(4), 386-9. https://doi.org/10.4103/0022-3859.143964
Fomda BA, et al. Prevalence and Genotypic Relatedness of Methicillin Resistant Staphylococcus Aureus in a Tertiary Care Hospital. J Postgrad Med. 2014;60(4):386-9. PubMed PMID: 25370547.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Prevalence and genotypic relatedness of methicillin resistant Staphylococcus aureus in a tertiary care hospital. AU - Fomda,B A, AU - Thokar,M A, AU - Bashir,G, AU - Khan,A, AU - Kour,A, AU - Zahoor,D, AU - Ray,P, PY - 2014/11/6/entrez PY - 2014/11/6/pubmed PY - 2015/8/28/medline SP - 386 EP - 9 JF - Journal of postgraduate medicine JO - J Postgrad Med VL - 60 IS - 4 N2 - BACKGROUND: Methicillin-resistant Staphylococcus aureus (MRSA) is the most common multidrug-resistant pathogen causing nosocomial infections across the world. MRSA is not only associated with significant mortality and morbidity but also places a large economic strain on our health care system. MRSA isolates are also typically resistant to multiple, non-β-lactam antibiotics. We conducted a prospective study in a tertiary care hospital, to determine the prevalence of MRSA and to establish the clonal distribution of MRSA isolates recovered from various clinical specimens. MATERIALS AND METHODS: Clinical samples were cultured and S. aureus was identified as per standard microbiological procedures. Susceptibility testing was done by agar disk diffusion and minimum inhibitory concentration (MIC) method as recommended by CLSI. Methicillin resistance was detected by phenotypic methods namely, oxacillin disc diffusion (ODD), minimum inhibitory concentration (MIC) of oxacillin, cefoxitin disk diffusion (CDD), and MIC of cefoxitin. Amplification of mecA gene by PCR was used as gold standard for detection of methicillin resistance. Pulsed field gel electrophoresis (PFGE) typing was performed for MRSA isolates. RESULTS: Out of 390 S. aureus isolates, 154 (39.48%) isolates were MRSA and 236 (60.51%) isolates were MSSA. Penicillin was the least effective antibacterial drug against the hospital associated S. aureus isolates with 85.64% resistance rate. All the isolates were susceptible to vancomycin. The MRSA showed a high level of resistance to all antimicrobials in general in comparison to the MSSA and the difference was statistically significant (P < 0.05). Multiplex PCR performed for all strains showed amplification of both the mecA and nucA genes in MRSA strains whereas MSSA strains showed amplification of only nucA gene. PFGE of these isolates showed 10 different patterns. CONCLUSION: Prevalence of MRSA in our hospital was 39.48%. Most of these isolates were resistant to erythromycin, clindamycin, cotrimoxazole, and ciprofloxacin, whereas high sensitivity was seen to vancomycin followed by gentamicin. CDD and MIC for cefoxitin showed 100% sensitivity, specificity, PPV and NPV as compared to PCR for mecA gene. In maximum number of isolates PFGE type A pattern was seen suggesting clonal relatedness. SN - 0972-2823 UR - https://www.unboundmedicine.com/medline/citation/25370547/Prevalence_and_genotypic_relatedness_of_methicillin_resistant_Staphylococcus_aureus_in_a_tertiary_care_hospital_ L2 - http://www.jpgmonline.com/article.asp?issn=0022-3859;year=2014;volume=60;issue=4;spage=386;epage=389;aulast=Fomda DB - PRIME DP - Unbound Medicine ER -