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ThesisItem Open Access Bacterial quality of milk at the point of production with special emphasis o the quality assuarance programme(Department of Veterinery Public Health, College of Veterinary and Animal Science, Mannuthy, 2006) Lekha, Chacko K; KAU; Nanu, EIn the present study a total of 108 milk samples were collected from farmers of three societies (S1, S2 and S3) and analysed for microbial quality, by estimating various microbial counts and also by assessing the presence of certain bacteria of public health importance. Antibiotic susceptibility of Escherichia coli and Staphylococcus aureus was also evaluated. The samples were graded based on total viable count and also by methylene blue reduction test. The critical control points of bacterial contamination of milk at various stages of production were also assessed during the investigation. Analysis of variance test of the data revealed highly significant difference (P0.01) between the mean counts of milk samples collected from three societies. Milk samples from S2 had the highest mean total viable count (6.57 ± 0.13 log10 cfu/ml), coliform count (3.89 ± 0.08 log10 cfu/ml), Escherichia coli count (1.11 ± 0.19 log10 cfu/ml), faecal streptococcal count (3.86 ± 0.08 log10 cfu/ml) and psychrotrophic count (5.57 ± 0.12 log10 cfu/ml). But the highest mean yeast and mould count (4.08 ± 0.01 log10 cfu/ml) was observed in samples collected from S1. Milk samples from S2 revealed maximum contamination. Analysis of data revealed that highly significant (P<0.01) and positive correlation between various bacterial counts. Highly significant (P<0.01) and positive association was observed between total viable count and psychrotrophic count and also between the former count and faecal streptococcal count. Microbial analysis of milk samples collected from six farmers of S1 revealed that samples from F4 had highest mean total viable count (7.44 ± 0.01 log10 cfu/ml) and the lowest in samples of F3 (4.82 ± 0.03 log10 cfu/ml). Similarly, the other bacterial counts, viz., coliform count, Escherichia coli count, faecal streptococcal count, psychrotrophic count was also seen in the highest level in the samples of F4. Whereas the highest mean yeast and mould count was observed in the samples of F1. Microbial analysis of the samples collected from farmers of S2 revealed that the highest mean total viable count (7.42 ± 0.08 log10 cfu/ml) and coliform count (4.44 ± 0.08 log10 cfu/ml) was seen in the samples of F5. Whereas these counts were lowest in the samples of F2. But the Escherichia coli count was highest in the samples collected from F3. However, the organism was not detected in the samples of F2 of S2. The highest mean faecal streptococcal count and psychrotrophic count was also seen in samples of F5, indicating that the hygienic practices followed by the farmer is very poor. Microbial analysis of the milk samples collected from six farmers of S3 revealed that the samples from F4 had the highest mean total viable count, coliform count, Escherichia coli count, faecal streptococcal count and psychrotrophic count indicating the poor hygienic practices followed by the farmer. The highest yeast and mould count was observed in the samples of F6. The presence of these organisms revealed the unsanitary condition of production of milk. The public health impact on the consumer was assessed by isolation and identification of Escherichia coli, Staphylococcus aureus, Listeria monocytogenes, Bacillus cereus, Yersinia enterocolitica, Aeromonas and Salmonella. The presence of coliforms and faecal streptococci indicate unhygienic handling of milk and possible faecal contamination. Escherichia coli was isolated from 41.67 per cent of the samples examined. A total of 45 isolates were obtained. Only 22 (48.89 per cent) out of 45 isolate were serotyped. The isolates fell into 10 serotypes viz., O116, O24, O84, O145, O172, O125, O79, O87, O103 and O157. Out of these serotypes except 024, 079 and 087 showed a positive congo red binding test which indicate the property of pathogenisity of isolates. Staphylococcus aureus was isolated from 33 (30.56 per cent) samples. The highest number of isolates was obtained from S2 (14) followed by S1 (12) and S3 (7). Listeria monocytogenes was isolated from 3 (2.70 per cent) samples. All isolates were obtained from F5 of S1. Bacillus cereus was isolated from 3.70 per cent of the total samples. Of the four isolates obtained, one was from S3 and three from S2. The per cent of isolation of Aeromonas was 18.51. Two species of Aeromonas were obtained viz., Aeromonas hydrophila and Aeromonas caviae. None of the samples tested revealed the presence of salmonella and Yersinia enterocolitica. Antibiogram of Escherichia coli isolates obtained from the samples belonging to various sources revealed that all isolates were sensitive to chloramphenicol, co-trimoxazole and gentamicin. None of the isolates showed resistance to all the antibiotics used. Antibiogram of Staphylococcus aureus isolates revealed that all the isolates were sensitive to chloramphenicol. Highest per cent (36.36) of organisms showed resistance against erythromycin followed by oxytetracycline (21.22). None of the isolates revealed resistance to all the antibiotics used. Milk samples collected from three societies were graded based on total viable count. Out of the 108 samples analysed 16.67, 29.63, 20.37 and 33.33 per cent were graded as very good, good, fair and poor quality based on BIS (1977). However 16.67 per cent from S1 and 33.33 from S3 were graded as very good. The per cent of samples graded as good, fair and poor from S1 was 19.44, 30.56 and 33.33, respectively. However, the corresponding per cent from S2 was 33.33, 16.67 and 50.00. The per cent of good, fair and poor samples from S3 was 36.11, 13.89 and 16.67, respectively. Milk samples collected from three societies were graded based on methylene blue reduction test and the result showed that 22.22, 34.26, 25.00 and 18.52 per cent of samples were graded as very good, good, fair and poor, respectively. The various critical control points of bacterial contamination of milk was evaluated by collecting samples of air, water, rinsinging of utensils, hand wash of the milker and udder washes of the animals and estimating their bacterial load. The highest bacterial counts were observed in the hand wash samples of the milker, followed by udder wash of the animal and these two were considered as the point of major source of contamination of milk. The highest bacterial counts in water, utensil rinsings, hand wash of milker and udder washes of animal were observed in samples collected from S2. Thus it may be inferred that the high bacterial load of milk samples from S2 might be due to the contamination of milk from these sources. Therefore, utmost care should be given to monitor the microbial quality of milk at various stages of production, and also to identify various sources of bacterial contamination of milk. Then only we can improve the quality and shelf life of milk produced.ThesisItem Open Access Bacterial quality of raw milk at the co-operative society level with special reference to quality assuarance programme(Department of Veterinary Public Health, College of Veterinary and Animal Sciences, Mannuthy, 2006) Jaibi, K; KAU; Nanu, EA total of 144 raw milk samples, consisting of individual and pooled milk samples collected from three societies, viz. S1, S2 and S3 were tested to assess the microbial quality by determining Total Viable Count (TVC), Coliform Count (CC), Escherichia coli Count (ECC), Faecal Streptococcal Count (FSC), Psychrotrophic Count (PC), and Yeast and Mould Count (YMC). The presence of certain bacterial pathogens like Escherichia coli, Staphylococcus aureus, Listeria monocytogenes, Bacillus cereus, Yersinia enterocolitica, Aeromonas and Salmonella was also assessed. Statistical analysis of the data revealed highly significant difference (P<0.01) in microbial counts of individual samples of the three sources. The overall mean total viable count, coliform count, faecal streptococcal count, psychrotrophic count, and yeast and mould count was 6.12 ± 0.07, 3.27 ± 0.04, 3.06 ± 0.05, 3.81 ± 0.06, 3.48 ± 0.07 log10 cfu/ml, respectively. Escherichia coli was not detected in 61.11 per cent of individual samples. The overall Escherichia coli count of the samples was 1.23 ± 0.15 log10 cfu/ml. Samples of S2 had the highest mean count. Highly significant (P<0.01) and positive correlation was observed between all the bacterial counts. Association between total viable count and psychrotrophic count, total viable count and coliform count and coliform count and psychrotrophic count was the highest. Anlaysis of variance test of the data revealed highly significant (P<0.01) difference between the bacterial count of the 36 pooled milk samples obtained from the three sources. The overall mean total viable count, coliform count, faecal streptococcal count and psychrotrophic count were 6.52 ± 0.08, 3.47 ± 0.07, 1.52 ± 0.27, 3.37 ± 0.07 and 4.26 ± 0.07 log10 cfu/ml, respectively. Significant (P<0.05) difference was observed in the mean yeast and mould count of pooled milk samples and the overall mean count was 3.85 ± 0.09 log10 cfu/ml. The highest mean microbial count was observed in the samples of S2. Highly significant (P<0.01) and positive correlation was observed between total viable count and other bacterial counts. The correlation between psychrotrophic count and other counts was also very high. Among the individual samples of S1, highest mean total viable count was seen in the samples of F4 (6.75 ± 0.07 log10 cfu/ml) and the lowest mean count was in the samples of F2 (4.68 ± 0.05 log10 cfu/ml). The highest coliform count and psychrotrophic count were observed in the samples of F4 and the lowest count was seen in the samples of F2. Samples of F4 had the highest Escherichia coli count (2.68 ± 0.54 log10 cfu/ml). and the lowest count was observed in the samples of F6 (1.04 ± 0.66 log10 cfu/ml). None of the samples of F2 and F3 revealed the presence of the organism. Faecal streptococcal count was the highest in the samples of F5 and the lowest mean count was in the samples of F2. The mean yeast and mould count was the highest in samples of F4 (4.26 ± 0.06 log10 cfu/ml) and the lowest in the samples of F2 (2.25 ± 0.07 log10 cfu/ml). The association between psychrotrophic count and the other bacterial counts was highly significant (P<0.01). Highly significant (P<0.01) association was also observed between total viable count and coliform count. The total viable count of individual samples of S2 showed highly significant (P<0.01) difference. Samples of F2 had the highest mean count (6.72 ± 0.06 log10 cfu/ml). The lowest mean count was observed in the samples of F6 (6.09 ± 0.08 log10 cfu/ml). All bacterial count, except Escherichia coli count was highest in the samples of F2. The highest Escherichia coli count was in the samples of F3. All the microbial counts, except faecal streptococcal count was lowest in the samples of F6. Faecal streptococcal count was lowest in the samples of F3. Total viable count of samples of farmers belonging to S3 showed highly significant (P<0.01) difference. The samples of F1 had the lowest count (4.74 ± 0.04 log10 cfu/ml) and the highest count was observed in the samples of F6 (6.72 ± 0.05 log10 cfu/ml). All microbial counts were highest in the samples of F6. Escherichia coli was isolated from 38.89 per cent individual samples and 47.22 per cent of pooled milk samples. Only 23 isolates from individual samples and eight isolates from pooled milk samples were serotyped. The serotypes obtained were O5, O24, O25, O68, O84, O87, O103, O116, O157 and O172. Out of the isolates, 14 and five from individual samples and seven and two from pooled samples were untypable and rough, respectively. Congo red binding property was shown by 17 serotyped and 10 untypable isolates obtained from individual milk samples and five serotyped and four untypable strains obtained from pooled milk samples. Staphylococcus aureus was isolated from 28.70 per cent of individual and 27.78 per cent of pooled milk samples. Listeria monocytogens was isolated from two individual milk samples from S3. Bacillus cereus was isolated from two milk samples obtained from S2. Aeromonas was isolated from 12.04 per cent of individual samples and 25.00 per cent of pooled milk samples. From the individual samples, seven isolates of Aeromonas sobria and six isolates of Aeromonas caviae were obtained. From the pooled milk samples, three isolates of Aeromonas hydrophilia and six isolates of Aeromonas caviae were obtained. Antibiogram of the Escherichia coli isolates revealed that the isolates were highly sensitive to cephotaxime, chloramphenicol, ciprofloxacin and gentamicin whereas 11.86 per cent isolates were resistant to streptomycin. Staphylococcus aurues isolates were sensitive to cephotaxime, chloramphenicol, ciprofloxacin and gentamicin. But 19.51 per cent and 9.76 per cent isolates were resistant to erythromycin and penicillin, respectively. Grading of individual milk samples based on total viable count as per the standards prescribed by Indian Standards (1977), revealed that 42.59 per cent samples were graded as fair. Only 16.67 per cent samples were graded as very good whereas 20.37 per cent each were graded as good and poor. None of the pooled milk samples was graded as very good, while 16.67, 58.33 and 25.00 per cent samples were graded as good, fair and poor, respectively. Based on methylene blue reduction test, 21.30, 30.56, 39.81 and 8.33 per cent individual samples were graded as very good, good, fair and poor, respectively while, 13.89, 30.56, 47.22 and 8.33 per cent pooled milk samples were graded as very good, good, fair and poor, respectively. The various critical control points of microbial contamination of milk was evaluated by collecting samples of air, water, hand wash of the handler and utensil wash and subjecting to estimation of the bacterial load. Hand wash was found to be a major source of contamination. The highest microbial count in the samples of air and hand wash was observed in S2. The higher mean microbial count in the milk samples of S2 might be attributed to the contamination from these sources. The microbial count in water and utensil wash was the highest in the samples of S1.