Distribution of Arcobacter butzleri and its correlation with faecal contamination in the aquatic environment.

Arcobacter butzleri, a foodborne pathogen of increasing public health relevance and associated with the gut of warm blooded animals is widely distributed in aquatic environments. Its association with the extensively studied faecal indicator, Escherichia coli remains unclear, yet is important for clarifying the ecology of pathogens and assessing risks. This study evaluated the prevalence and correlation between A. butzleri and E. coli in finfish, shellfish and water sampled across multiple contamination points- markets, landing centres, and fishing vessels in Mumbai, India. A total of 70 samples (30 finfish, 30 shellfish, 10 water) were tested using a miniaturized Most Probable Number-quantitative Polymerase Chain Reaction (MPN-qPCR), which bypasses lengthy culture procedures and offers a reliable approach in the absence of a standard isolation method for A. butzleri. A. butzleri was present in 73% of the samples and E. coli in 81% samples indicating a high microbial burden of both organisms within this seafood ecosystem.. Contamination varied by source, with market samples showing highest levels, followed by landing centres and lowest from on-board vessels, indicating post-harvest contamination influenced by nearshore water pollution. Regression analysis indicated positive correlation between A. butzleri and E. coli (ρ = 0.88, R² = 0.78, p < 0.001) and particularly robust associations were observed in shellfish and water matrices. This supports the close association of A. butzleri with sewage-impacted environments and its potential role as a supplementary indicator of fecal contamination.