Document Type : Original Article
Authors
1
Microbiology and Immunology department, faculty of pharmacy,Zagazig University, Zagazig, Egypt
2
Department of Microbiology and Immunology, Faculty of Pharmacy, Zagazig University, Egypt
Abstract
The study aimed to compare the sensitivity of Staphylococcus isolates from hospital and non hospital sources to some commonly used antibiotics and biocides, and to investigate whether resistance to either types of antimicrobials are correlated. The minimum inhibitory concentrations (MICs) of the antibiotics and biocides were determined for clinical (47), hospital environment (64) and non hospital (33) isolates using agar dilution method. Arithmetic progression in biocides concentration was used instead of the geometric progression for antibiotics. Pearson's correlation coefficients (r) between MIC-MIC, Log MIC-Log MIC, and MIC-Log MIC for individual biocides and antibiotics, respectively, were compared. Also, the frequencies of antibiotic resistance among biocide-susceptible and biocide-resistant isolates were calculated. The antibiotics included: ampicillin, penicillin G, oxacillin, cefepime, streptomycin, tetracycline, gentamicin, azithromycin, ciprofloxacin, vancomycin and chloramphenicol, while biocides included chlorocresol, benzalkonium chloride, cetrimide, chlorhexidine, phenyl mercuric nitrate, povidone-iodine and ethidium bromide. Hospital isolates showed higher resistance rates to antibiotics and biocides and more predominance of methicillin resistance compared to non-hospital isolates. The most likely correlation between antibiotic and biocide resistance was best expressed by comparing log MIC of antibiotic with MIC of biocide. For hospital isolates, positive correlations were found between increased resistance to most of tested antibiotics (except for vancomycin and occasionally ciprofloxacin and tetracycline) and reduced susceptibility to biocides, except for chlorhexidine and povidone-iodine. For non hospital isolates, only resistance to benzalkonium chloride and cetrimide correlated with resistance to most of the tested antibiotics. Except for chlorhexidine and povidone-Iodine higher resistance rates to antibiotics were found among biocide resistant isolates.
Keywords
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