EXISTENCE OF VANCOMYCIN RESISTANCE AMONG METHICILLIN RESISTANT S. aureus RECOVERED FROM ANIMAL AND HUMAN SOURCES IN EGYPT

Abstract

The increased resistance of vancomycin among methicillin resistant Staphylococcus aureus (MRSA) has produced a major formidable threat in the therapeutic field. The current study analyzed the vancomycin resistance traits among MRSA isolates recovered from 148 samples of animal and human origins in Sharkia Governorate, Egypt. All staphylococci isolates were examined against 8 antimicrobials and vancomycin minimal inhibitory concentrations (MICs) were then determined among phenotypic vancomycin resistant and intermediate S. aureus. Furthermore, all vancomycin-resistant S. aureus (VRSA) isolates were exposed to PCR analysis of mecA and van genes. Herein, 45 of 86 Staphylococcus spp. were identified as S. aureus, while 41 were coagulase negative staphylococci (CoNS). A higher incidence rate of S. aureus was observed in meat products (58.06%), but majority of CoNS isolates were isolated from milk samples (54.54%) with no statistical differences (P < 0.05) in the distribution of S. aureus and CoNS among all samples. Oxacillin and amoxicillin-clavulanic acid recorded the highest resistance percentages among S. aureus (93.33 and 88.89%) and CoNS (75.61 and 87.80%), respectively. Multidrug resistance (MDR) was detected in high proportions of S. aureus (64.4%) and CoNS (34.1%). Forty-two of 45 S. aureus isolates were MRSA, of which 14 were vancomycin resistant with MIC values ranged from 32-1024 μg/mL. PCR detection of mecA and van genes in the tested isolates revealed that they were all mecA gene positive, while 10 out of them had van genes. The vanB gene was found in 5 isolates with higher MICs (64- 256 μg/mL), while vanA gene was detected in 4 isolates with MICs of 128-512 μg/mL and only one isolate harbored both vanA and vanB genes with MIC value of 1024 μg/mL. According to the upsurge of VRSA prevalence rates, more attentions should be oriented for continuous monitoring of antimicrobial usage with the need for effective drugs against VRSA.