Assessment of the microbiological quality of fresh tilapia fish sold at three markets in Kampala City, Uganda

Abstract

A microbiological analysis of tilapia for determination of Total Viable Count (TVC), Pseudomonas load and coliform count, was carried out on samples obtained from three different markets in Kampala City, Uganda. The study was carried out between September and December 2021. A total of 30 fresh tilapia fish of same size were collected from the three markets. The area of the fish skin was measured and approximate 216cm2 was obtained for each sample. From each fish sample, a sterile cotton was used to swab the whole skin whose area was 216 cm2 and then placed in 9mls of 0.1% Peptone water to make a 1/10 dilution. From each dilution, the samples were analyzed for Total Viable Count, Coliform count and Pseudomonas load using Plate count agar, MacConkey agar and King’s B agar respectively. Samples from Market 1 had the highest contamination compared to those from Market 3 with mean TVC of 2.45×108 cfu/cm2 and 1.01×105cfu/cm2, respectively. Generally, fifteen fish samples (50%) from all the three markets had acceptable TVC values. The mean TVC on fish samples from market 1 and 2 were greater than the acceptable limits whereas those in market 3 were acceptable. Samples from Market 1 had the highest contamination with coliforms compared to those from Market 3 with mean coliform counts of 4.40×106 cfu/cm2 and 1.72×105 cfu/cm2, respectively. All the fish samples from the three markets had unacceptable values of coliform counts when compared to the limits. Samples from Market 1 had the highest Pseudomonas load as compared to those from Market 3 with mean counts of 3.84×107cfu/cm2 and 4.00×105 cfu/cm2, respectively. Generally, twenty-three fish samples (90%) from all the three markets had acceptable Pseudomonas load. The mean Pseudomonas load on fish samples from market 1 and 2 were greater than the acceptable limits whereas those in market 3 were acceptable. Generally, there was a significant difference (p = 0.045) in the TVC enumerated from the fish samples obtained from the three markets; more specifically for fish samples from market 1 and market 3 (p = 0.036). There was no significant difference in the mean coliform count (p = 0.736) and the mean Pseudomonas load (p = 0.190) in fish samples from the three markets. It is therefore recommended that improvements in quality control systems, hygienic handling of fish should be adhered to in order to minimize contamination and hence the rate of deterioration of the fish quality. A similar study is should be carried out to quantify the bacterial load on individual fish species in different regions of the country.