Microbiological Quality of Raw Cow's Milk at Collection Centers in Trinidad

Differences in sheep and goats milk microbiological profile between conventional and organic farming systems in Greece

The aim of this study was to examine differences in the microbiological profile and antimicrobial resistance of bacteria isolated from milk from organic and conventional sheep and goat farms. Twenty-five organic and 25 conventional sheep and goat farms in the region of Thessaly, Greece participated in this study. A standardised detailed questionnaire was used to describe farming practices. A total of 50 samples were collected and analysed for total viable count (TVC), total coliform count (TCC) and somatic cell count (SCC), while Staphylococcus aureus and Escherichia coli were isolated using standard methods. Isolates were identified at species level by Api-test and Matrix-Assisted Laser Desorption/Ionisation-Time of Flight Mass Spectrometry (MALDI-TOF MS). Susceptibility to a panel of 20 for E. coli and 16 for S. aureus antimicrobials was determined by the agar dilution method. Pulsed Field Gel Electrophoresis (PFGE) was performed for S. aureus and E. coli isolates to determine predominant clones. Lower counts of TVC, TCC and SCC were identified in milk from the organic farms, possibly due to differences in the hygienic farming practices found on those farms. API-tests and MALDI-TOF MS showed no significant differences in the S. aureus and E. coli isolates. Overall, antimicrobial resistance rates were low, while a statistically higher percentage was estimated among strains originating from conventional farms in comparison with organic farms, possibly due to the restriction of antibiotic use in organic farming. PFGE revealed diversity among S. aureus and E. coli populations in both organic and conventional farms indicating circulation of 2-3 main clones changing slightly during their evolution. Consequently, there is evidence that milk from the organic farms presents a better microbiological profile when compared with milk from conventional farms.

An overview of food safety and bacterial foodborne zoonoses in food production animals in the Caribbean region

Foodborne diseases (FBDs) in the Caribbean have a high economic burden. Public health and tourism concerns rise along with the increasing number of cases and outbreaks registered over the last 20 years. Salmonella spp., Shigella spp., and Campylobacter spp. are the main bacteria associated with these incidents. In spite of undertaking limited surveillance on FBD in the region, records related to bacterial foodborne zoonoses in food-producing animals and their associated epidemiologic significance are poorly documented, giving rise to concerns about the importance of the livestock, food animal product sectors, and consumption patterns. In this review, we report the available published literature over the last 20 years on selected bacterial foodborne zoonoses in the Caribbean region and also address other food safety-related aspects (e.g., FBD food attribution, importance, surveillance), mainly aiming at recognizing data gaps and identifying possible research approaches in the animal health sector.

Quality and safety of raw cow’s milk in Slovakia in 2011

The quality and safety of raw cow’s milk is very important for dairy companies and consumers of milk products. Due to the methods of production, it is impossible to completely eliminate contamination of milk with microorganisms, therefore the microbial content of milk is a major feature in determining its quality. Other important factors to consider include somatic cells count, veterinary drug residues, milk composition and freezing point. Somatic cells represent the udder health and can be used for monitoring of subclinical mastitis. A high level of somatic cells can increase proteolysis in milk which affects technological processes. Veterinary drugs administered to cows may lead to residues in the milk which are harmful to humans. The content of fat, protein and solids-non-fat are the main indicators used by dairies for technological purposes. In this article we discuss the quality and safety of raw cow’s milk in Slovakia during 2011. We found that 73.53% of samples tested for somatic cell count, and 84.54% of samples tested for total bacterial count, met the European Union legislation limits. We found the largest decrease in fat and protein content was during the summer period and the largest increase was in the winter period. We found that 92.14 %, 98.7% and 91.38% of samples met the limit presented in STN 570529:1999 for fat content, protein content and freezing point respectively. The percentage of drug positive samples was 0.087%.

Inhibition of growth of pathogenic bacteria in raw milk by legume protein esters

Protein isolates from soybean and chickpea, as well as their methylated esters, were tested for their inhibitory action against the propagation of pathogenic bacteria in raw milk during its storage either at room temperature or under refrigeration. Raw milk was inoculated with a mixed culture of Listeria monocytogenes Scott A and Salmonella enterica serovar Enteritidis strain PT4 at ca. 2 log CFU ml⁻¹. Aerobic plate count, coliform count, and presumptive E. coli in raw milk treated with esterified legume proteins were inhibited by 2 to 3 log relative to a control after 6 to 8 days of storage at 4°C. At room temperature, bacterial populations (aerobic plate count, coliform count, and presumptive E. coli) in raw milk treated with esterified legume proteins were inhibited by ca. 1.5 to 1.6 log relative to the control after 12 h. Supplementation of raw milk with esterified soybean protein could significantly inhibit the counts of the two inoculated pathogens (L. monocytogenes Scott A and Salmonella Enteritidis PT4), which were initially inoculated at ca. 2 log CFU ml⁻¹, by ca. 2.4 log and 1.6 log CFU ml⁻¹, respectively, on day 8 of storage under cold conditions. Corresponding reductions amounting to 2.7 and 1.8 log CFU ml⁻¹ were observed after 12 h of storage at room temperature. Supplementation of raw milk with esterified soybean protein (0.5%) reduced the maximum level of titratable acidity to 0.21 and maintained the pH level at 6.4 after 8 days of storage under cold conditions as compared with 4 days for untreated raw milk. Similar results were observed when raw milk was stored at room temperature for 10 h.

Characterization of Staphylococcus aureus isolated from poultry meat in Spain

Ninety-six Staphylococcus aureus isolates from retail chicken carcasses in Spain were characterized using cultural and biochemical tests. The strains were phage typed with the international bacteriophage set for typing S. aureus of human origin. Eighty-eight (91.7%) strains were of the poultry ecovar. Strains of human ecovar were not found. These facts are congruent with findings of other authors. Ninety (93.7%) strains were phage typeable. Lysis by phages of Group III was the most frequent with 66 (68.7%) sensitive strains. Twenty-eight (29.2%) strains were sensitive at 100 routine test dilution (RTD) and only 16 (16.7%) at RTD. By using reversed phage typing, we managed to increase the number of phage typeable strains by 46 (47.9%). More than one S. aureus phage type was detected in 14 (35%) carcasses, which emphasizes the convenience of subtyping several S. aureus isolates from the same food sample in epidemiological studies. Two phage patterns (75/84 and 6/1030/ W57) were the most common. The S. aureus isolates were closely related, as 78 strains showed the most common or indistinguishable (<2 phage reaction differences) phage patterns.

Study on risk factors and their association with subclinical mastitis in lactating dairy cows in Trinidad

A cross-sectional study was conducted on dairy farms in eight milking centres in Trinidad to determine the prevalence of risk factors for mastitis and to assess their relationship to occurrence of subclinical mastitis. The California mastitis test (CMT) was used to determine the prevalence of subclinical mastitis by estimating the somatic cell counts in bulk and composite milk. Of a total of 177 dairy farms studied, 121 (68.4%), 39 (22.0%) and 17 (9.6%) practised semi-intensive, extensive and intensive management systems, respectively. A total of 129 (72.9%), 37 (20.9%) and 11 (6.2%) farms milked cows in parlours, stanchions and pasture/out-on-field, respectively. Based on sanitary practices, 40 (22.6%), 123 (69.5%), and 14 (7.9%) farms were classified as good, fair, and poor, respectively, while 76 (42.9%) and 60 (33.9%) farms reported to rarely experience and frequently experience water shortages, respectively. Amongst the 177 farms, only seven (4.0%) used machine-milking primarily, 152 (85.9%) screened for mastitis as a routine, 18 (10.2%) teat dipped, and 49 (27.7%) practised dry cow therapy. To detect mastitis, of 152 farms involved, 20 (13.2%) used the strip cup while only two (1.3%) employed the CMT. Pipe-borne water delivered directly from the hose was the only source of water to 91 (51.4%) farms while seven (4.0%) and eight (4.5%) farms used only well and surface water (ponds and rivers), respectively. Based on bulk milk samples, the farm prevalence of subclinical mastitis was 60.5% (107 of 177) with a range from 33.3% (centre 5H) to 100.0% (centre 2B). The difference was statistically significant (P < 0.01; chi 2). However, using composite milk, the farm prevalence of subclinical mastitis was 52.5% (93 of 177) with a range from 21.2% (centre 5H) to 92.9% (centre 2B) and again, the difference in prevalence was statistically significant (P < 0.001; chi 2). Subclinical mastitis was detected in 150 (45.0%) of 333 lactating cows screened and the range of prevalence was from 17.9% (centre 5H) to 56.3% (centre 1C). The difference was statistically significant (P < 0.001; chi 2). Of a total of 14 risk factors for mastitis studied which were related to animal husbandry, personnel, mastitis control and water, only two, the herd size and practice of dry cow therapy were significantly (P < 0.05; chi 2) associated with subclinical mastitis. It was concluded that the high prevalence of subclinical mastitis in Trinidad dairy herds could significantly reduce milk production with associated economic loss. Although a majority of the risk factors studied were not found to be significantly associated with the occurrence of subclinical mastitis possibly due to confounding factors, the need to eliminate or reduce these risk factors cannot be over-emphasized.

Relatedness of Staphylococcus aureus strains isolated from milk and human handlers in dairy farms in Trinidad

The susceptibility of S. aureus strains isolated from milk and human handlers in dairy farms in Trinidad to bacteriophages was determined. Of the 110 strains isolated from bulk milk, 73 (66.4%) were typable either at routine test dilution (RTD) or 100-RDT compared to 108 (72.5%) of 149 strains from composite milk sensitive but the difference was not statistically significant (P > or = 0.05; chi 2). Strains of S. aureus from human handlers had significantly (P < or = 0.05; chi 2) lower sensitivity, with only 90 (59.6%) of 151 strains typable. Phages in various groups were predominantly more active on both milk isolates, 54.1% (98 of 181) and human strains, 73.3% (66 of 90). Phage 42D alone lysed 22 (12.2%) but with other phages typed 90 (49.7%) of 181 typable strains from milk compared to a lytic activity of only 1.1% (1 of 90) alone and 35 (38.9%) with other phages for strains isolated from human handlers. The differences were however not statistically significant (P > or = 0.05; chi 2). Relatedness of S. aureus strains isolated from bulk milk, composite milk and human handlers on each farm was demonstrated in 21 (46.7%) of 45 dairy farms using the phage patterns detected. Similarly, the relatedness of S. aureus strains isolated from the anterior nares and hands of each human milker was detected on 10 (35.7%) of 28 dairy farms studied. It was concluded that S. aureus strains from human milkers contaminated both composite and bulk milk on the farms studied while bovine strains of S. aureus were also acquired by humans during milking.