Bacterial contamination of milk and antimicrobial resistance profiles of selected pathogens in Kiboga District

Abstract

Milk when not properly handled during transportation and storage, favors growth of several microorganisms. Many factors exist in the cattle corridor of Uganda that suggest bacteria contamination of milk during transport to collection centres is an issue. A study was carried out to determine the bacteria contamination of milk along the transportation chain in Kiboga district using total plate counts (TPC) and characterize some of the isolated pathogenic bacteria using drug resistance/susceptibility patterns and molecular typing for resistance against vancomycin. Milk samples from 50 farms were collected at the farm and the same milk followed upto the collection centres and again collected. Bacteria contamination of raw milk was enumerated by TPC. The mean TPC was 6.16 X 106 cfu/ml in the farms and 6.62 X 107 cfu/ml in the collection centres with a minimum of 0 in the farms and 2300 cfu/ml in the collection centres. The maximum TCP was 48.6 X 106 cfu/ml in the farms and 1 X 109 cfu/ml in the collection centres. Generally, higher milk contamination was observed at the collection centres than in the farms (p = 0.000). Bacteria with the wide drug resistance patterns were Klebshiela spp and E.coli whereas those with the narrow resistance patterns were Staphylococcus aureus and Streptococcus spp. Pen G was the most inefficient drug with the following resistance patterns: Staphylococcus aureus 48%, CNS 91%, Klebsiella 96%, E.coli 100% and Streptococcus ssp 15%. The most effective drug was Ciprofloxacin with a susceptibility pattern among isolates as follows: Staphylococcus aureus 96%, CNS 61%, Klebsiella 100% and Streptococcus ssp 62%. The Van A gene associated with vancomycin resistance was detected in one Staphylococcus aureus isolate. No Van B gene was identified amongst the 15 vancomycin resistant isolates screened suggesting presence of other genetic markers for vancomycin resistance. In conclusion the bacteria contamination of milk in Kiboga district deteriorated during transportation due to the increase in bacterial load.