ABSTRACT
Background and objectives: staphylococcus aureus [S. aureus] is a very successful hospital and community-acquired pathogen. Methicillin-resistant S. aureus [MRSA] is a major cause of hospital acquired infection worldwide. The number of MRSA strains isolated from community-acquired infections [CA-MRSA] has increased. Most of CA-MRSA strains carry the Panton-Valentine leukocidin [PVL] gene at a high level of incidence. We aimed to determine the prevalence of PVL genes among S. aureus isolates, association with various types of staphylococcal disease and determine the characters of PVL-positive isolates from hospital and community setting
Materials and methods: 386 S. aureus isolates, 182 community-acquired and 204 nosocomial S. aureus isolates were enrolled in the present study. Antimicrobial susceptibility for all isolates was done and methicillin resistance was confirmed by 1[micro]g oxacillin and 30[micro]g cefoxitin disk diffusion. All isolates were tested for the presence of PVL genes [lukS-PV and lukF-PV] using specific primer sequences and polymerase chain reaction amplification
Results: twenty three [5.95%] S. aureus isolates were positive for carrying the PVL genes. The majority of them 16/182[8.79%] community acquired isolates were from skin and soft tissue infections [abscesses [n = 8], cellulitis [n =3], skin lesions [n = 2], and boils [n = 3]]. Among 182 communities acquired S. aureus, 53 isolates were CA MRSA, 7[13.20%] of them were PVL-positive and 129 CA-MSSA, 9[6.97%] of them were PVL positive. On the other hand, only 7/204[3.43%] hospital acquired isolates were from other sites of infection [pneumonia [n = 3], wound [n = 2], septicemia [n = 2]]. Five [3.06%] PVL positive isolates were cured from 163 hospital associated MRSA [HA-MRSA] and 2[4.87%] out of 41 HAMSSA. Antimicrobial susceptibility patterns differed among the PVL-positive isolates. Twelve [52.17%] were resistant to methicillin and oxacillin. Several of the isolates were resistant to penicillin and ampicillin 19[82.60%], gentamicin 13[56.52%], fusidic acid and trimethoprim 10[43.47%], tetracycline 9[39.13%], erythromycin 6[26.08%], cefotaxime 5[21.74%], chloramphenicol 4[17.39%], and while resistance to ciprofloxacin, was rare 1[4.34%]. All isolates were susceptible to vancomycin
Conclusion: the PVL genes are carried by a relatively low number of S. aureus isolates. These isolates were associated mostly with necrotic infections of the skin and soft tissue. We recommend test MRSAs for susceptibility to ciprofloxacin as a marker of putative CA-MRSA since the majority of HA-MRSA are resistant to ciprofloxacin