Bacterial Analysis of Different Types of Milk (Pasteurized, Unpasteurized and Raw Milk) Consumed in Kathmandu Valley

Abstract

Objectives: The presence of pathogenic bacteria in milk is the major public health concern resulting in food borne illness. The aim of this study is to determine the microbial quality of three different types of milk consumed in Kathmandu Valley with respect to the acceptable standard guideline and measure the antibiotic susceptibility pattern of the Escherichia coli and Staphylococcus aureus isolates.Methods: A total of 66 samples (16 pasteurized, 25 unpasteurized and 25 raw milk) were collected from various sites of Kathmandu Valley. Those samples were subjected for total plate count and total coliform count by pour plate method. Furthermore, identification was made for the presence of E. coli and S. aureus with biochemical tests.Results: The mean total plate count (TPC) of pasteurized, unpasteurized and raw milk was 1.2X106 cfu/ml, 2.3 X 107 cfu/ml and 2.0 X 107 cfu/ml respectively. And, the mean total coliform count (TCC) of pasteurized, unpasteurized and raw milk was 2.9 X 104cfu/ml, 6.3 X 105 cfu/ml and 1.6 X 105 cfu/ ml respectively. Coliforms were detected in 50%, 84% and 56% of the pasteurized, unpasteurized and raw milk sample respectively. E. coli and S. aureus were isolated from 18.8% and 12.5% of pasteurized, 40% and 16% of unpasteurized and 20% and 24% of the raw milk samples respectively. Among total E. coli isolates (n=18), 16.7% were susceptible to ampicillin whereas 100% isolates were susceptible to other tested antibiotics. Similarly, 33.3% and 66.7% of the isolated S. aureus were susceptible to penicillin and cefoxitin respectively, whereas all S. aureus isolates were sensitive to all other antibiotics.Conclusion: The mean value of TPC and TCC of pasteurized and raw milk exceed the standard guideline by FDA. Higher total plate count and presence of coliforms (also E. coli) and S. aureus in this study necessitates the close monitoring of the pasteurization process and post pasteurization process (packaging, transportation, storage etc.).

Microbiological Quality and Adulteration of Pasteurized and Raw Milk Marketed in Dharan, Nepal

“…Additionally, higher prevalence rates might be due to unhygienic processing, improper cleaning, deficient handling, and contamination of utensils. In contrast, our result was lesser than the findings of former studies by Acharya et al (2017), Dahal et al (2010), Aaku et al (2004), Mwangi et al (2000), Moustafa et al (1988) and Mohamed & El Zubeir (2007) who found the average value of 104.71×10 5 CFU/ml, 107 CFU/ml, 107×10 6 CFU/ml, 1×10 9 CFU/ml and 5.63×10 9 CFU/ml respectively. The differences in findings of these studies can be correlated to difference in time as well as place.…”

“…Furthermore, the prevalence of E. coli, S. aureus and Thermoduric bacteria in raw milk were 55%, 45% and 95% respectively (Table 2 and 3). E. coli was reported in 18.75% and 20% of pasteurized milk samples by Acharya et al (2017) and Parajuli et al (2018) respectively which is just lesser than results of this study.…”

“…Hence, the result of this study complied with the study done by DFTQC showing that most of the milk being sold in Nepal might be microbiologically unsafe for consumption. A similar study was done by Acharya et al (2017) and reported the Total Coliform count range from 2-52% in raw milk. The higher coliform count detected in this study may be due to poor hygiene of farm, use of contaminated water while milking and use of contaminated utensils by farmers.…”

“…It suggests that proper handling of milk, improvement in sanitation, proper sterilization and disinfestations of contaminated utensils and use of safe water is mandatory for all stakeholders In this study, 80% of pasteurized and 95% of raw milk samples were tested positive with an average Coliform count of 14×10 3 CFU/ml and 14×10 4 CFU/ml respectively (Table 3). This finding was higher than some previous studies (Silva et al, 2010;El Nahas et al, 2015 andAcharya et al, 2017). The annual report published by DFTQC (2011/2012) reported that out of 65 milk and milk products analyzed, 31 (47%) milk samples were found to be microbiologically unsafe (DFTQC, 2011).…”

Antibiogram of Escherichia coli and Staphylococcus aureus isolated from milk sold in Kathmandu district

“…However, as both harmful and beneficial microbes can reside in milk and higher microbial load does not necessarily indicate the exact type of microbes present in the milk, it may not be appropriate to gauge the quality of milk solely based on microbial load unless each of the microbial strain in the milk are identified. The quality issue aside, apparently similar prevalence of higher microbial load in pasteurized milk in Kathmandu was documented in a [17]. Even the DFTQC, Nepal reported the higher rate of noncompliance among milk and milk product in the annual bulletin of 2019 [18].…”