Bacteriological assessment of crab (Pachycheles pubescens) and dog whelk (Nucella lapillus) shellfishes from mesotidal estuarine ecosystem

Abstract

Background: Shellfishes are susceptible to a wide variety of bacterial pathogens, most of which are capable of causing disease in humans but are  considered to be saprophytic in nature. Bacteriological diversity of shellfishes depends on the fishing grounds, habitats and environmental factors  around them. This study assessed the bacteria associated with shellfishes, Pachycheles pubescens (crab) and Nucella lapillus (dog whelk) harvested from mesotidal estuarine ecosystem.

Methodology: The bacteriological assessment of crab (Pachycheles pubescens) and dog whelk (Nucella lapillus) harvested from Okwano Obolo estuary in  Eastern Obolo local government area (LGA), Akwa Ibom was evaluated. The density of heterotrophic and potential pathogens was determined using  standard analytical procedures. The pure bacterial isolates were grouped into recognizable taxonomic units and characterized to their generic level.

Results: The mean (and range) total heterotrophic bacterial count (THBC), total coliform count (TCC), faecal coliform count (FCC), Salmonella-Shigella  count (SSC) and total Vibrio count (TVC) of the crab samples (log10 cfu/g) for the crab samples are; 4.281±0.085 (4.18-4.39); 4.187±0.078 (4.11-4.30); 4.115±0.081 (4.00-4.20); 4.076±0.058 (4.00-4.14); and 4.114±0.085 (4.00-4.23) respectively (p=0.003915). For the dog whelk samples, the mean (and range)  THBC, TCC, FCC, SSC and TVC are 4.232±0.095 (4.11-4.36); 4.185±0.095 (4.04-4.28); 4.082±0.068 (4.00-4.18); 4.062±0.055 (4.00-4.15) and 5.155±0.062  (4.08-4.23) respectively (p=0.028856. Bacterial species isolated from the crab and dog whelk samples included Salmonella, Bacillus, Shigella,    Corynebacterium, Pseudomonas aeruginosa and Vibrio (which was the most frequently isolated bacteria pathogen from both samples in 80%).

Conclusion: Some of the bacteria species especially Vibrio, Salmonella and Shigella isolated from the crab and dog whelk samples are known human  pathogens, that can pose serious health risk if these seafoods are not properly cooked before consumption.