Faecal Contaminants in Edible Bivalves from Maputo Bay, Mozambique: Seasonal Distribution, Pathogenesis and Antibiotic Resistance

摘要

In Maputo, Mozambique marine bivalves considerably contribute to the diet of the population. This studyaimed to investigate seasonal distribution of Escherichia coli and Salmonella in clams from Maputo Bay, and examinetheir pathogenesis and antibiotic-resistant patterns. Standard multiple tube method revealed that the concentration of coliformsin all samples exceeded the limit for direct consumption, according to EU standards. Thirty-eight percent of thesamples contained >60,000 MPN per 100 gram flesh. The occurrence of E. coli did not differ significantly due to season,while Salmonella was present in 100% of the samples during the rainy period and only in 30% during the dry. Multiplexpolymerase chain reaction showed that 45% of E. coli isolates were positive for the virulent indicator gene fimA. The Salmonellaisolates were identified as S. enterica serovar Typhimurium. Among other isolated coliformic Enterobacteriaceae,Shigella sp. (specie), which in low doses can cause severe gastrointestinal infections, was identified. Antimicrobial susceptibility,recorded by the disk diffusion method, showed resistance to the most commonly used antibiotics. This highlevels of faecal contaminants in the clams points out the need for risk assessment and sanitary improvements.