Salmonella enterica serotypes isolated for the first time in laying hens, and their susceptibility to antibiotics

In this study, a total of 323 drag swab samples were taken from laying hen fresh feces from 3 different provinces (Kırklareli, Edirne, and Tekirdağ), which are located in the European part of Türkiye. According to the ISO 6579: 2002 method, 17.3% of the samples were found positive for Salmonella. Obtained 56 Salmonella isolates were serotyped by slide agglutination using antisera according to Kauffmann White Le Minor Scheme. Sixteen serotypes of Salmonella were identified as S. Typhimurium (28.6%), S. Kentucky (17.9%), S. Abony (16.1%), S. Infantis (8.9%), S. Enteritidis (5.4%), S. Anatum (3.6%), S. Saintpaul (3.6%), S. Szentes (1.8%), S. Dibra (1.8%), S. Fallowfield (1.8%), S. Kimuenza (1.8%), S. Escanaba (1.8%), S. Nagoya (1.8%), S. Mbandaka (1.8%), S. Agona (1.8%), and Salmonella II 17: e, n, x, z15: 1,6 (1.8%). Isolations of S. Kimuenza, S. Escanaba, and S. Nagoya from laying hens are reported for the first time in Türkiye. The isolations of S. Dibra, S. Fallowfield, S. Szentes, and Salmonella II 17: e, n, x, z15: 1,6 from laying hens are the first report in the world. A total of 56 Salmonella isolates were tested for susceptibility to amoxicillin-clavulanic acid, cefepime, azithromycin, cefoxitin, and trimethoprim/sulfamethoxazole by the disk diffusion method. While 10% of S. Kentucky isolates were resistant to ofloxacin, and S. Kimuenza was only resistant to chloramphenicol.

Prevalence, Serovars, and Factors Associated with Salmonella Contamination of Chicken Carcasses Sold in Outlets of the Informal Market in Gauteng Province, South Africa

ABSTRACT

Salmonella has been linked to many foodborne illnesses and epidemics in both humans and animals. This cross-sectional study determined the prevalence, serovars, and factors associated with Salmonella contamination of chickens slaughtered in informal market outlets in Gauteng Province, South Africa. A total of 151 chicken carcasses were randomly collected from 47 outlets. Standard bacteriological and molecular methods were used to isolate, identify, and determine the serovar of Salmonella isolates. The prevalence of Salmonella in carcass swabs, cloacal swabs, and carcass drips was 29.1% (44 of 151), 27.2% (41 of 151), and 43.7% (66 of 151), respectively, and the differences were statistically significant (P = 0.004). Only 5 (township locations of outlet, throughput, carcass evisceration, location of carcass for sale, and outlet sanitation) of 10 factors investigated for the contamination of carcasses by Salmonella were statistically significantly (P < 0.05) associated with the isolation of Salmonella. Of the 268 isolates of Salmonella, 157 (58.6%) were typeable using a limited molecular PCR technique, and nine serovars were identified. The predominant Salmonella enterica serovars were Bovismorbificans (31.0%), Enteritidis (7.5%), and Hadar (6.7%). The five important factors found to be significantly associated with the isolation of Salmonella at these outlets offer opportunities for the reduction of Salmonella contamination. There is a need for further investigation of the probable causes of the predominant isolation of Salmonella serovar Bovismorbificans in chickens and its potential implications for human infections in South Africa. It is concluded that chickens purchased from the informal market in Gauteng Province can be a source for salmonellosis in humans if improperly cooked before consumption.

Prevalence, biosecurity factor, and antimicrobial susceptibility analysis of Salmonella species isolated from commercial duck farms in Korea

Duck meat consumption in South Korea has increased in recent years, but no standard about duck farm-specific biosecurity and hygiene guidelines have yet been established. We here investigated Salmonella contamination levels in duck farms to evaluate biosecurity and hygiene practices. We collected 1,116 environmental samples from 31 duck farms in Jeonnam Province, South Korea. The Salmonella-positive farm rate dramatically increased, from 22.6 to 71.0%, on introduction of ducklings. As the ducklings aged 4-6 wk, the positive rate slightly decreased to 64.5%. The Salmonella detection rate on each sampled surface, such as the feed pan (34.4%), wall (33.9%), litter (32.3%), and nipples (24.2%), was highest at 3 wk of age. The most frequently detected Salmonella serovars were Salmonella London (22.2%), Salmonella Albany (21.6%), Salmonella Bareilly (17.0%), and Salmonella Indiana (16.5%). Implementation of cleaning and disinfection procedures, rodent control, and metal house walls significantly lowered the prevalence of Salmonella (P < 0.001, P < 0.01, and P < 0.05, respectively). A high proportion of Salmonella isolates exhibited antimicrobial resistance: 100 and 62.9% exhibited resistance to erythromycin and nalidixic acid, respectively. Furthermore, a majority of S. Albany and all Salmonella Enteritidis isolates were multidrug resistant. These results indicate the level of Salmonella contamination in duck farm environments in Korea is high. Good biosecurity and hygiene practices are the most effective measures for controlling Salmonella contamination.

Occurrence and Characterization of Salmonella Isolated from Table Egg Layer Farming Environments in Western Australia and Insights into Biosecurity and Egg Handling Practices

The aim of this study was to investigate the occurrence and distribution of Salmonella in commercial layer farming environments of 26 flocks belonging to seven egg businesses (free-range and barn-laid) in Western Australia (WA). Between November 2017 and June 2018, a total of 265 environmental samples of dust, feed, water, pooled feces, and boot swabs were tested for detection of Salmonella according to standard culture-based methods. Isolates were assayed for serovar and subtyped by multilocus sequence typing (MLST). Salmonella spp. were recovered from 35% (93/265) of all tested samples. Dust (53.8%, 28/52) and pooled fecal (54.5%, 18/33) samples provided the highest Salmonella recovery rates. Nine different Salmonella serovars were characterized across the positive (n = 93) environmental samples, of which S. Typhimurium (60/93, 64.5%) and S. Infantis (21/93, 22.5%) were the most prevalent. MLST revealed that all S. Typhimurium isolates were of sequence type ST-19. Microbiological screening of Salmonella was not routinely practiced in any of the surveyed egg businesses. Some of the egg businesses exhibited variable levels of compliance with basic biosecurity measures as well as high-risk egg handling practices. Egg businesses in WA should be encouraged to adopt a voluntary program of environmental sampling and verification testing for Salmonella. Such voluntary programs will aid in supporting solutions for the management of this pathogen in the human food chain.

Salmonella spp. contamination in commercial layer hen farms using different types of samples and detection methods

The performance of detection methods (culture methods and polymerase chain reaction assay) and plating media used in the same type of samples were determined as well as the specificity of PCR primers to detected Salmonella spp. contamination in layer hen farms. Also, the association of farm characteristics with Salmonella presence was evaluated. Environmental samples (feces, feed, drinking water, air, boot-swabs) and eggs were taken from 40 layer hen houses. Salmonella spp. was most detected in boot-swabs taken around the houses (30% and 35% by isolation and PCR, respectively) follow by fecal samples (15.2% and 13.6% by isolation and PCR, respectively). Eggs, drinking water, and air samples were negative for Salmonella detection. Salmonella Schwarzengrund and S. Enteritidis were the most isolated serotypes. For plating media, relative specificity was 1, and the relative sensitivity was greater for EF-18 agar than XLDT agar in feed and fecal samples. However, relative sensitivity was greater in XLDT agar than EF-18 agar for boot-swab samples. Agreement was between fair to good depending on the sample, and it was good between isolation and PCR (feces and boot-swabs), without agreement for feed samples. Salmonella spp. PCR was positive for all strains, while S. Typhimurium PCR was negative. Salmonella Enteritidis PCR used was not specific. Based in the multiple logistic regression analyses, categorization by counties was significant for Salmonella spp. presence (P-value = 0.010). This study shows the importance of considering different types of samples, plating media and detection methods during a Salmonella spp. monitoring study. In addition, it is important to incorporate the sampling of floors around the layer hen houses to learn if biosecurity measures should be strengthened to minimize the entry and spread of Salmonella in the houses. Also, the performance of some PCR methods and S. Enteritidis PCR should be improved, and biosecurity measures in hen farms must be reinforced in the region of more concentrated layer hen houses to reduce the probability of Salmonella spp. presence.