Shelly Rodrigo

Microbial health risk posed by table eggs in Trinidad

A survey of the microbial quality of table eggs sold in Trinidad was conducted. For 23 poultry layer farms each visited twice approximately 1 month apart, 25 pooled eggs constituted a composite sample, for 14 shopping malls each visited twice approximately 1 month apart, six pooled eggs made a composite sample and for a total of 102 other retailers across the country each visited once over a 4-month period, six pooled eggs constituted a composite sample. Swabs of egg shells and egg content were tested for selected bacteria. Twenty-four (13.0%), 68 (37.0%), and two (1.1%) of a total of 184 composite eggs (shells, egg content or both) sampled were positive for Salmonella, Escherichia coli, and Campylobacter respectively. All 184 samples tested were negative for Listeria spp. Salmonella was recovered from seven (3.8%) egg shell samples only compared with 14 (7.6%) egg content samples only positive for the pathogen. Fifty-two (28.3%) egg shell samples and seven (3.8%) egg content samples were positive for E. coli. Both isolates of Campylobacter coli originated from egg contents. Of a total of 24 composite egg samples positive for Salmonella, eight different serotypes of Salmonella were isolated from a total of 24 Salmonella-positive composite eggs of which S. Enteritidis was the most prevalent, 58.3% (14/24). Salmonella Georgia was isolated for the first time in Trinidad. Failure to properly handle or heat table eggs sold in Trinidad poses a potential health hazard to consumers because of their poor microbial quality.

Prevalence of antimicrobial residues in table eggs in Trinidad.

The prevalence of antimicrobial residues in pooled table eggs from layer farms, shopping malls, and supermarkets in Trinidad was determined. A total of 23 layer farms and 14 shopping malls were sampled twice, 1 month apart, whereas 102 supermarkets were each sampled once. For each farm, 25 eggs were randomly collected and pooled to constitute a composite sample, whereas six eggs from each farm source available at sale outlets were randomly sampled from malls and supermarkets to constitute a composite sample. Questionnaires were administered at the farms to determine the occurrence of risk factors for contamination of antimicrobial residues in eggs and at sale outlets to determine storage conditions. The Charm II test was used to qualitatively detect antimicrobial residues (beta-lactams, macrolides, sulfonamides, and tetracyclines). Of 46 composite eggs tested from farms, 3 (6.5%) were contaminated with residues compared with 5 (16.1%) of 31 and 16 (15.0%) of 107 mall and supermarket eggs, respectively, but the difference was not statistically significant (P > 0.05). The residues detected were as follows: sulfonamides, 12 (6.5%) of 184; macrolides, 7 (3.8%) of 184; tetracycline, 5 (2.7%) of 184; and beta-lactam, 0 (0.0%) of 184. The difference was statistically significant (P < 0.05). The use of medicated feeds on farm, claim of adherence to the antimicrobial withdrawal period, and temperature of egg storage did not significantly (P > 0.05) affect the prevalence of residues in eggs. It was concluded that the presence of antimicrobial residues, particularly sulfonamides, in table eggs could be of public health significance to the consumer.

Occurrence of Selected Foodborne Pathogens on Poultry and Poultry Giblets from Small Retail Processing Operations in Trinidad

We conducted a study to determine quantitatively and qualitatively the presence of Campylobacter spp., Escherichia coli, staphylococci, total coliforms, total aerobic bacteria, and Salmonella on broiler carcasses from selected small retail processors in Trinidad. We used standard media and procedures for detection and quantification. All carcass and weep samples were positive for aerobic bacteria, E. coli, total coliforms, and staphylococci. Significant differences in the mean counts of aerobic bacteria were observed for samples of carcass (P = 0.001), weep (P = 0.038), and liver and heart (P = 0.017). There was a significant difference (P < 0.05) in the prevalence of E. coli and Campylobacter for liver and heart samples and gizzard samples across various areas (health divisions) in Trinidad and for Campylobacter jejuni and Campylobacter coli for offal samples. The prevalence of Salmonella in carcass, drip, gizzard, and liver and heart samples was 7.3, 3.1, 2.1, and 1.0%, respectively, and three serotypes, Salmonella Kiambu (53.8%), Salmonella Kentucky (38.5%), and Salmonella Mbandaka (7.7%) were isolated. Of the six groups of microbes considered with respect to sale activity, the differences in the prevalence of Campylobacter in medium-activity sale shops (95.8%) and low-activity sale shops (83.3%) and the mean counts of staphylococci for medium-activity sale shops (5.5 +/- 0.9) and low-activity sale shops (5.1 +/- 0.8) were statistically significant (P < 0.05). Carcasses rinsed in a stagnant system had a significantly higher (P < 0.05) prevalence (92.3%) and mean count per milliliter (3.1 +/- 0.7) for Campylobacter compared with 77.8% and 2.7 +/- 0.7 for shops that rinsed with constantly running water. The frequency of rinse water change significantly (P = 0.04) affected the prevalence of Salmonella on carcasses. It is recommended that a quality control system be introduced for these shops, particularly with respect to evisceration and rinsing practices.

Survey of Salmonella Contamination in Chicken Layer Farms in Three Caribbean Countries

This study was conducted to investigate the demography, management, and production practices on layer chicken farms in Trinidad and Tobago, Grenada, and St. Lucia and the frequency of risk factors for Salmonella infection. The frequency of isolation of Salmonella from the layer farm environment, eggs, feeds, hatchery, and imported day-old chicks was determined using standard methods. Of the eight risk factors (farm size, age group of layers, source of day-old chicks, vaccination, sanitation practices, biosecurity measures, presence of pests, and previous disease outbreaks) for Salmonella infection investigated, farm size was the only risk factor significantly associated (P = 0.031) with the prevalence of Salmonella; 77.8% of large farms were positive for this pathogen compared with 33.3 and 26.1% of medium and small farms, respectively. The overall isolation rate of Salmonella from 35 layer farms was 40.0%. Salmonella was isolated at a significantly higher rate (P < 0.05) from farm environments than from the cloacae. Only in Trinidad and Tobago did feeds (6.5% of samples) and pooled egg contents (12.5% of samples) yield Salmonella; however, all egg samples from hotels, hatcheries, and airports in this country were negative. Salmonella Anatum, Salmonella group C, and Salmonella Kentucky were the predominant serotypes in Trinidad and Tobago, Grenada, and St. Lucia, respectively. Although Salmonella infections were found in layer birds sampled, table eggs appear to pose minimal risk to consumers. However, the detection of Salmonella -contaminated farm environments and feeds cannot be ignored. Only 2.9% of the isolates belonged to Salmonella Enteritidis, a finding that may reflect the impact of changes in farm management and poultry production in the region.

Resistance to antimicrobial agents among Salmonella isolates recovered from layer farms and eggs in the Caribbean region.

This investigation determined the frequency of resistance of 84 isolates of Salmonella comprising 14 serotypes recovered from layer farms in three Caribbean countries (Trinidad and Tobago, Grenada, and St. Lucia) to eight antimicrobial agents, using the disc diffusion method. Resistance among isolates of Salmonella was related to the country of recovery, type of sample, size of layer farms, and isolate serotype. Overall, all (100.0%) of the isolates exhibited resistance to one or more of seven antimicrobial agents tested, and all were susceptible to chloramphenicol. The resistance detected ranged from 11.9% to sulphamethoxazole-trimethoprim (SXT) to 100.0% to erythromycin. The difference was, however, not statistically significant (P = 0.23). Across countries, for types of samples that yielded Salmonella, significant differences in frequency of resistance were detected only to SXT (P = 0.002) in Trinidad and Tobago and to gentamycin (P = 0.027) in St. Lucia. For the three countries, the frequency of resistance to antimicrobial agents was significantly different for ampicillin (P = 0.001) and SXT (P = 0.032). A total of 83 (98.8%) of the 84 isolates exhibited 39 multidrug resistance patterns. Farm size significantly (P = 0.032) affected the frequency of resistance to kanamycin across the countries. Overall, among the 14 serotypes of Salmonella tested, significant (P < 0.05) differences in frequency of resistance were detected to kanamycin, ampicillin, and SXT. Results suggest that the relatively high frequency of resistance to six of the antimicrobial agents (erythromycin, streptomycin, gentamycin, kanamycin, ampicillin, and tetracycline) tested and the multidrug resistance detected may pose prophylactic and therapeutic concerns for chicken layer farms in the three countries studied.

Biotypes and serotypes of Campylobacter spp. isolated from broilers in Trinidad

Purpose – This paper sets out to investigate the biotypes of Campylobacter jejuni and C. coli and the serotypes of C. jejuni present in broilers from selected small retail processors in six counties in Trinidad.Design/methodology/approach – Samples were plated on blood‐free Campylobacter CCDA, incubated at 42°C in 8‐10 per cent CO2 in a CO2 incubator and isolates were biotyped using the Lior scheme and serotyped using 25 Penner heat‐stable antisera by the passive hemagglutination method.Findings – Amongst the 743 C. jejuni isolates biotyped, 85.3 per cent and 14.7 per cent belonged to biotype I and II respectively compared with C. coli isolates where 84.3 per cent were grouped as biotype I and 15.7 per cent were biotype II amongst a total of 681 isolates. The difference in frequency of both biotypes amongst C. jejuni and C. coli was statistically significant (p<0.05; χ2). Of the 52 isolates of C. jejuni, 48 (92.3 per cent) were typable. The predominant serotype Penner HS O:31 accounted for 19.2 per cent o...