Prevalence of community-acquired methicillin-resistant Staphylococcus aureus from inmates of the Manila City Jail, characterization for SCCmec type and occurrence of Panton-Valentine leukocidin gene

Abstract

Methicillin-resistant Staphylococcus aureus (MRSA) has established itself as a significant cause of hospital and community-acquired infections worldwide. Resistance to methicillin compromises clinical treatment options, as it results in cross resistances to all other β-lactam antibiotics, which are the most commonly prescribed antibacterial agents. The study determined the prevalence of MRSA among inmates of the Manila City Jail with and without pyoderma, their antibiograms (susceptibility to other antimicrobial agents), SCCmec type and occurrence of the lukslukf Panton-Valentine leukocidin (PVL) virulence gene among the isolates. Methicillin resistance was determined using oxacillin and cefoxitin discs and the detection of mecA gene and its product, PBP2a. The MRSA isolates were studied for their SCCmec types and for the presence of the PVL gene using multiplex polymerized chain reaction and nucleotide sequencing. Staphylococcus aureus was isolated from 78% of 105 inmates M with pyoderma, 41% of which were resistant to methicillin, giving an overall prevalence rate of 32% among the infected inmates. Nasal carriage rates of S. aureus and MRSA among 104 inmates without pyoderma were 12% and 5%, respectively. All MRSA were susceptible to vancomycin; 35% and 44% were susceptible to erythromycin and clindamycin, respectively. Intermediate susceptibility to erythromycin and clindamycin was seen in 59% and 50%, respectively, while 6% were resistant to each of erythromycin and clindamycin. PBP2a and mecA gene were present in 94% of the 35 MRSA isolates tested. SCCmec type IV was demonstrated in 30 of the 33 isolates with mecA gene, while the remaining three were of SCCmec type I. PVL gene was detected in 83% of MRSA isolates. Nucleotide sequencing of the PCR amplicons from representative isolates studied all showed a G to C transversion at position 1004 of the luks-lukf gene, resulting in the substitution of valine (GTT) with leucine (CTT). This is the first report on the prevalence of MRSA carrying SCCmec type IV and the PVL genes in the Philippines and in a jail setting. Type IV mecA is the most easily transferred SCCmec, and its acquisition converts methicillin susceptible strains to resistance, while luks-lukf PVL is a composite of virulence genes that results in more serious infections. The study shows that community-acquired infection with this strain exists, and can be a growing problem that has to be fully addressed immediately to prevent further spread not only within the crowded penitentiary, but in the community as well.