Erythromycin Resistance in Bacterial Isolates from Patients with Respiratory Tract Infections in Ikere-Ekiti, Nigeria

The occurrence of erythromycin resistance in bacteria causing respiratory tract infections varies among populations and is associated with inappropriate antibiotic usage. This study was undertaken to determine erythromycin resistance in bacterial isolates from patients with respiratory tract infections in Ikere-Ekiti. Bacteria were isolated from sputum specimens using standard microbiological protocols while the antibiotic susceptibility pattern of isolates was determined using the Kirby-Bauer method. Erythromycin resistance genes: mefA, ermA, and ermB were detected using multiplex polymerase chain reaction (PCR). Out of the 157 bacterial isolates identified using standard microbiological methods, Klebsiella spp. 40 (25%) was the most frequent followed by Staphylococcus aureus 34 (22%) and Proteus spp. 34 (22%) while Streptococcus spp., Escherichia coli, and Bacillus spp. had 19 (12%), 20 (13%), and 10 (6%) respectively. Most of the bacterial isolates were resistant to penicillin 148 (94%), cloxacillin 147 (93.6%), amoxicillin-clavulanic acid 141 (90%), erythromycin 141 (90%), and tetracycline 124 (79%). However, the isolates were least resistant to trimethoprim-sulfamethoxazole 57 (36%). Out of the 48 bacterial isolates investigated using multiplex PCR amplification for erythromycin resistance genes, 10 (20.8%) were positive for mefA, 3 (6.3%) were positive for ermA, and 2 (4.2%) were positive for ermB. The association between the presence of mefA, ermA, and ermB genes and erythromycin resistance was not significant (p=0.464). The presence of erythromycin resistant genes in pathogenic bacterial isolates from the respiratory tract was revealed in this study. Awareness of the risk of self-medication and abuse of antibiotics should be emphasized.