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Indian Journal of Medical Microbiology
Medknow Publications on behalf of Indian Association of Medical Microbiology
ISSN: 0255-0857 EISSN: 1998-3646
Vol. 29, Num. 3, 2011, pp. 318-319

Indian Journal of Medical Microbiology, Vol. 29, No. 3, July-September, 2011, pp. 318-319

Correspondence

Antibiotic resistance and molecular subtypes of clinical methicillin-resistant Staphylococcus aureus in a teaching hospital

E Zeinali, R Moniri, GH Musavi

Departments of Microbiology and Immunology, School of Medicine, Kashan University of Medical Sciences, Kashan; Department of Biostatic, School of Health, Kashan University of Medical Sciences, Kashan, Iran
Correspondence Address: R Moniri, Departments of Microbiology and Immunology, School of Medicine, Kashan University of Medical Sciences, Kashan; Department of Biostatic, School of Health, Kashan University of Medical Sciences, Kashan, Iran, moniri@kaums.ac.ir

Date of Submission: 14-Mar-2011 
Date of Acceptance: 13-Jun-2011

Code Number: mb11080

PMID: 21860123

DOI: 10.4103/0255-0857.83926

Dear Editor,

Emergence of multi-drug resistant methicillin resistant Staphylococcus aureus (MDR-MRSA) has profoundly affected the choice of empirical treatment for staphylococcal infection. This descriptive study was done on 87 MRSA isolates which were collected from the clinical samples of patients from a tertiary teaching hospital in Kashan, Iran, in 2010. The isolates were tested for antibiotic resistance by the disc diffusion method for 10 antimicrobials. The MRSA genotypes were determined by a multiplex polymerase chain reaction (PCR) based on the staphylococcal cassette chromosome mec (SCCmec).

All the isolates remained susceptible to vancomycin and low resistance rates were noted for amikacin (13.8%). Three (3.4%) of MRSA strains were SCCmec type I, 12 (13.8%) SCCmec type II, 8 (9.2%) SCCmec type IVb, 4 (4.6%) SCCmec type IVd and 3 (3.4%) SCCmec type V. Interestingly, there was also a high frequency of non-typeable strains 51 (58.6%) as they did not show any characteristic bands.

The resistance rates of the isolates to 10 antimicrobial agents are summarised in [Table - 1]. The SCCmec type II is harboured by hospital acquired MRSA (HA-MRSA) and usually presents multi-drug resistant MRSA strains. [1] Other studies reported a higher prevalence of SCCmec type II in MRSA isolates. [2] No SCCmec type III element was detected in the MRSA isolates in this study in contrast to other reports of SCCmec type III (HA-MRSA) prevalence from 14 to 52%. [3],[4]

The second most common type was SCCmec type IVb which were all sensitive to amikacin but showed high resistance rates to erythromycin, clindamycin, tetracycline and sulfamethoxazole-trimethoprim. CA-MRSA is typically characterised by the presence of SCCmec IV, V or VII which is susceptible to non-β-lactams.[5]

In conclusion, all MRSA isolates from the teaching hospital were multi-drug-resistant, and SCCmec type II and type IV predominated. Effective hospital control practices need to be reinforced to avoid transmission of multi-drug resistant organisms.

References

1.File TM. Methicillin-resistant Staphylococcus aureus (MRSA): Focus on community-associated MRSA. South Afr J Epidemiol Infect 2008;23:13-5.  Back to cited text no. 1    
2.Kilic A, Haijing L, Stratton C. Antimicrobial susceptibility patterns and Staphylococcal cassette chromosome mec types of, as well a Panton-Valentine leukocidin occurrence among, methicillin-resistant Staphylococcus aureus isolates from children and adults in middle Tennessee. J Clin Microbiol 2006;44:4436-40.  Back to cited text no. 2    
3.Machado AB, Reiter KC, Paiva RM. Distribution of staphylococcal cassette chromosome mec (SCCmec) types I, II, III and IV in coagulase-negative staphylococci from patients attending a tertiary hospital in southern Brazil. J Med Microbiol 2007;56:1328-33.  Back to cited text no. 3    
4.Makgotlho PE, Kock MM, Hoosen A, Lekalakala R, Omar S, Dove M, et al. Molecular identification and genotyping of MRSA isolates. FEMS Immunol Med Microbiol 2009;57:104- 15.  Back to cited text no. 4  [PUBMED]  [FULLTEXT]
5.Takano T, Higuchi W, Otsuka T, Baranovich T, Enany S, Saito K, et al. Novel characteristics of community-acquired methicillin-resistant Staphylococcus aureus belonging to multilocus sequence type 59 in Taiwan. Antimicrob Agents Chemother 2008;52:837-45.  Back to cited text no. 5  [PUBMED]  [FULLTEXT]

Copyright 2011 - Indian Journal of Medical Microbiology

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