RESUMEN
To detect genes for enterotoxins, exfoliative and toxic shock syndrome toxins in Staphylococcus aureus [S. aureus] strains isolated from clinical specimens. Cross-sectional observational study. Department of Molecular Genetics, Dr. Ziauddin Hospital, Karachi, from January to December 2010. Two hundred and ninety eight S. aureus clinical isolates were obtained from various clinical samples received at Dr. Ziauddin Hospital, Karachi. Out of these, 115 were detected as methicillin resistant [MRSA] by cefoxitin disk diffusion test showing a prevalence rate of 38.6%. Detection of individual toxin genes was performed by Polymerase Chain Reaction [PCR] by using only one primer pair for each tube. Uniplex primers were preferred as multiplex primers are longer in base pairs and have the potential for cross reaction due to non-specific binding and increase in optimization time. The possession of a single gene or more than a single gene in MRSA isolates was found in 61.73% of clinical samples; the highest number was found in pus swab, followed by sputum, blood, urethral swab, and urine. The prevalence of toxin genes was higher in MRSA as compared to methicillin sensitive [MSSA] isolates [19.12%]. PCR detects strains possessing toxin genes independent of their expression. The possession of genes for super-antigens seems to be a frequent and habitual trait of S. aureus more so in MRSA
RESUMEN
The in vitro antimicrobial activity of Sea buckthorn [SBT] [Hippophaerhamnoides], Green tea [Camellia sinensis] and Dandasa [Juglansregia] on selected methicillin resistant Staphylococcus aureus [MRSA] isolates from clinical samples was tested. The in vitro antimicrobial activity of six antiseptics/disinfectants against MRSA isolated from environmental samples was also evaluated. Experimental Observational. This study was conducted in Immunology and Infectious Diseases Research Laboratory [IIDRL] Lab, University of Karachi from January 2011 to July 2011. Minimum Inhibitory Concentration [MICs] of plant extracts was determined by micro- broth dilution method and, susceptibility of MRSA isolates from environmental samples against antiseptics/ disinfectants was estimated by the agar disk diffusion and agar well diffusion methods. None of the plant extracts inhibited the isolates originating from blood samples. SBT offered comparatively more inhibitory zones and among the antiseptics/disinfectants, savion was the most effective. In view of the rising antibiotic resistance, exploring possible natural plant extracts for their antimicrobial action seems like an attractive substitute. The results showed some degree of susceptibility and can be suggested for use in vivo after standard clinical trials
RESUMEN
Methicillin-resistant Staphylococcus aureus [S. aureus] [MRSA] is an important pathogen in hospitals and communities. There is advance in technologies but infections by MRSA are difficult to diagnose. The current study was conducted to compare three phenotypic methods for with a genotypic method. Cross-sectional study. Methicillin resistance was tested in 450 isolates of S. aureus retrieved from various clinical samples received in Dr. Ziauddin Laboratory Department of Molecular Genetics [DMG], Karachi from January to October 2011. Methods used were, oxacillin disc diffusion, oxacillin screen agar, cefoxitin disc diffusion and Polymerase Chain Reaction [PCR] for mecA gene, which was taken as the gold standard. The Kirby Bauer disc diffusion, using cefoxitin discs 30microg, identified a total of 174 [38.6%] S. aureus isolates as methicillin resistant. With oxacillin disk diffusion test, 152 [33.77%] strains were MRSA with sensitivity of 87.35% and specificity of 100%. Oxacillin-agar screen detected 168 [37.33%] strains with sensitivity of 96.5% and specificity of 100%. PCR method detected mec A gene in 169 [37.55%] isolates with sensitivity of 97.12%, specificity of 100%. The cefoxitin disc diffusion, as suggested by the Clinical and Laboratory Standards Institute [CLSI], is a consistent method for MRSA diagnosis but must be augmented with other methods like oxacillin screen agar, so that no MRSA is overlooked. PCR although taken as the gold standard cannot be recommended as routine because of the high cost and time consumption