Antibiogram Testing of Bacterial Isolates from Cassava, Yam and Plantain Flours and Shelf Life Studies of the Products Sold in Some Markets in Port Harcourt, Nigeria

Abstract

Bacterial resistance to commonly used antibiotics is a threat to public health. This study focused on antibiogram testing of bacterial isolates from packaged and exposed cassava, plantain and yam flour using chloramphenicol, ciprofloxacin, erythromycin, levofloxacin, gentamicin, ampiclox, rifampicin, amoxil, streptomycin, norfloxacin, ampicillin, ceporex, tarivid, nalidixic acid, peflacine, augmentin and septrin. Shelf life studies involved monitoring total viable count, total fungal count and moisture content of the flour samples stored at room temperature (28± 2°C) at 1 Wk interval for 4 Wks. Standard methods and agar diffusion technique were adopted. Bacillus sp. and Staphylococcus sp. (Gram-positive) were identified in all the flour samples. Salmonella sp. and Escherichia coli (Gram negative) were isolated from exposed plantain and yam flour, respectively. Gram-positive isolates susceptible and resistant to each antibiotic ranged between 65.38-96.15% and 3.85-30.77%, respectively whereas that of Gram-negative isolates was between 25-75%. Antibiogram testing revealed that 76.92 and 30.77% of Bacillus and Staphylococci isolates, respectively were sensitive; 100% Salmonella sp. and E. coli (isolate OMY) was resistant and sensitive, respectively. Among antibiotics used for Gram-positive bacteria, rifampicin was most effective whereas streptomycin, tarivid, nalidixic acid, gentamycin, augmentin and ciprofloxacin were more effective than other antibiotics used for Gram negative bacteria. During storage of the flour samples, moisture content (8.6-23.20%) and total viable count (6.47-6.86 log10cfu/g) increased but total fungal count (3.53-2.15 log10cfu/g) decreased with few exceptions. Therefore, reduction in microbial contamination of edible flours by implementing good manufacturing practices and proper packaging of the commercialized products could reduce the spread of antimicrobial resistant bacteria.