In-vitro susceptibility patterns of some major respiratory tract pathogens in Nigeria to eleven selected antibiotics.

A study of the antibiotic sensitivity patterns of nine pathogens isolated from bronchopulmonary infections was made using the disc diffusion method. Erythromycin, carbenicillin and chloramphenicol were in that sequence the drugs most effective against the Gram-positive cocci, followed by ampicillin to which however, 56% of the strains of staphylococcus aureus tested showed resistance. More than 95% of the strains of Haemophilus influenza were very susceptible to carbenicillin and chloramphenicol while over 70% were sensitive to ampicillin, penicillin G, and erythromycin. All strains of Pseudomonas aeruginosa tested were sensitive to carbenicillin and gentamicin. Klebsiella pneumoniae was moderately sensitive to tetracycline, carbenicillin, streptomycin, gentamicin and septrin (co-trimoxazole). Sixty-seven percent of Escherichia coli were sensitive to septrin while 50% were susceptible to chloramphenicol, erythromycin and ampicillin. In general there was evidence that tetracycline, septrin, penicillin G, streptomycin and orbenin had become less effective against most of the respiratory tract pathogens. The study shows the necessity for the early identification of the aetiologic agents and their antibiotic sensitivity patterns so as to reduce the degree of wasteful polypharmacy or the development of high resistance rates in hospitals and their environments.