Antibiotics susceptibility of some Bacillus strains isolated in the ground and rainwater in urbanized area in Cameroon (Central Africa), and potential impact of the season change

Abstract

This study assessed the antibiotics susceptibility of Bacillus cereus, B. thuringiensis and B. subtilis strains isolated in wells and rainwater samples in Yaounde (Cameroon). Water samples in wells were collected monthly during a long dry season (LDS), a short dry season (SDS), a long rainy season (LRS) and a short rainy season (SRS), and during the LRS and the SRS for rainwater. The antibiotics considered included Imipenem, Amikacin, Gentamycin, Ciprofloxacin, Ofloxacin, Sulfamethazol, and Tetracycline. With strains from the groundwater, the antibiotic inhibition diameters varied from 9.13 mm (Sulfametazole during SDS) to 32.78 mm (Imipenem during LDS) with B. thuringiensis, from 8.2 mm (Sulfametazole during SDS) to 35.25 mm (Imipenem during LDS) with B. cereus, and from 5.05 mm (Ofloxacin during LRS) to 29.25 mm (Imipenem during LDS) with B. subtilis. With those from the rainwater, they varied from 4.55 mm (Sulfametazole during LRS) to 25.65mm (Imipenem during LRS) with B. thuringiensis, from 2.13 mm (Imipenem during LRS) to 20.05mm (Imipenem during SRS) with B. cereus, and from 5.03 mm (Gentamicin during SRS) to 25.15mm (Tetracycline during SRS) with B. subtilis. Bacillus strains isolated during LRS were multiresistant to the majority of antibiotics. The inhibition diameters of the most antibiotics varied significantly from one season to another (p