ABSTRACT
Methicillin resistant S. aureus [MRSA], besides having established itself as a major hospital pathogen, is now beginning to prevail in the community. However, several notable differences were found to exist between hospital acquired strains [HA-MRSA] and community acquired strains [CA-MRSA]. Panton-Valentine leukocidin gene [PVL] is a cytotoxin which was found to represents an important virulence factor in some strains of S. aureus which cause some sorts of severe infections. The aims of this study were to assess the association of PVL gene with HA-MRSA and CA-MRSA and the role of this gene in pathogenesis of these infections
Methods: Two groups of patients with different types of infections were included in this study: the first group included 150 patients with hospital acquired infections and the second group included 85 patients with community acquired infections. All isolated S. aureus strains were tested for methicillin resistance by determination of MIC [minimum inhibitory concentration] using agar dilution method. All the detected MRSA isolates were tested for the presence of PVL gene by polymerase chain reaction [PCR]
Results: within the isolated CA S. aureus strains, MRSA isolates were found to be significantly higher compared to MRSA isolates from HA S. aureus infections [30/52: 57.7% and 25/74: 33.7% respectively]. PVL gene was detectable in 16/30 [53.3%] of CA-MRSA isolates while this gene was not found in any of HA-MRSA [0/25: 0%]. In CAMRSA isolates, PVL gene was found in 2/2 [100%] of cases with pneumonia, 8/10 [80%] of cutaneous abscesses, 4/4 [100%] of cases with furunclosis, 1/3 [33.3%] of finger pulp infections, 1/2 [50%] of breast abscesses while no isolates from cases with cellulites, impetigo or osteomyelitis harbored the PVL gene
Conclusion: our results revealed that PVL gene is strongly associated with CA-MRSA while it is not associated with HA-MRSA. PVL gene is mostly associated with primary necrotic infections [abscesses, furunclosis and Pneumonia], but not with invasive and secondary infections commonly encountered in HA S. aureus infections. The results of this study drive the attention to the current increase of CA-MRSA in Egypt which makes implementation of infection control guidelines of great concern to prevent more dissemination of MRSA in the community or to hospitals. A wide scale study of CA and HA-MRSA is recommended on the national level in Egypt to investigate the general prevalence rate, pathogenesis and the changes in antibiotic resistance and their relations to PVL gene and other genetic and virulence factors which may allow better management and control of these infections