Nasal colonization and drug-resistance patterns of Staphylococcus aureus and Staphylococcus epidermidis among young residents within the vicinity of Calajunan Dumpsite, Mandurriao, Iloilo City

Abstract

Poor disposal and handling of wastes is one of the problems in developing countries as well as in urban places. Leachate, which includes potential pathogens like Staphylococcus aureus and Staphylococcus epidermidis, occurs when solid wastes adsorb moisture and may contaminate ground water sources. The increasing antibiotic resistance of these species poses a great risk to those exposed to the dumpsite. This study generally aimed to investigate nasal colonization by multidrug-resistant S. aureus and S. epidermidis in young residents of Barangay Calajunan, Mandurriao, Iloilo City and to evaluate the relationship between multidrug-resistance of S. aureus and S. epidermidis and possible risk factors such as direct exposure to the dumpsite, close contact with waste-pickers, antibiotic use, hospitalization, skin and soft-tissue infections, and personal hygiene. Nasal swabs were obtained from eighty-three young residents aged 5-14 years. Isolation and identification of Staphylococcus spp. were based on standard conventional biochemical methods such as mannitol fermentation, catalase and coagulase tests. Anti-staphylococcal agents for the detection of drug susceptibility patterns were penicillin G (10 units), oxacillin (1 µg), cefoxitin (30 μg), ampicillin (10 μg), vancomycin (30 μg), erythromycin (15 µg), tetracycline (30 µg), and clindamycin (2 µg). Of the fifty-one isolated presumptively identified staphylocococcal species, 92% (n=49) were identified as S. aureus and 4% (n=2) as S. epidermidis. The prevalence of nasal colonization of S. aureus and S. epidermidis among the study populace was 59% and 2.41%, respectively. Eighty-two percent (n=42) of the S. aureus isolates exhibited susceptibility to tetracycline, while 98% (n=48) exhibited resistance to ampicillin. One hundred percent (n=2) of the S. epidermidis isolates exhibited susceptibility to erythromycin and tetracycline, and resistance to penicillin G and ampicillin. Multidrug-resistant (MDR) strains were phenotypically determined based on non-sensitivity to two or more of the different antimicrobial classes. Sixty-one percent (n=31) of S. aureus isolates and 50% (n=2) of S. epidermidis were MDR strains. Of these staphylococcal isolates, 54.8% (n=17) were resistant to antimicrobials belonging to Penicillins and Glycopeptides with one isolate being S. epidermidis and 16 S. aureus. No significant association between multidrug resistance of S. aureus and S. epidermidis and the risk factors was observed among the study population (p>0.05), however, it was observed that those who bathed and washed more often were more likely to have both nasal colonization and multidrug resistance of S. aureus and S. epidermidis.