Isolation, identification and antimicrobial susceptibility profile of Salmonella isolated from poultry farms in Addis Ababa, Ethiopia

Occurrence, Risk Factors, and Antibiotic Resistance Patterns of Salmonella Isolates Obtained From Dairy Farms in Gondar Town, Northwest Ethiopia

Background: Salmonellosis is a foodborne diarrheal disease with significant public health and economic implications for humans and animals. Nevertheless, its epidemiological effects and multidrug resistance remain poorly studied in the study area. Methods: A cross-sectional study was conducted from March to August 2022 to determine the occurrence, risk factors, and antibiotic susceptibility patterns of Salmonella isolates in the study dairy farms. A total of 232 samples (200 study animals and 32 bulk tank milk) were collected from purposively selected dairy farms in the study area. Again, fecal and bulk tank milk samples were collected, pre-enriched, and cultured to examine the presence of Salmonella following standard techniques. The pure 30 isolates were also subjected to a Kirby-Bauer disk diffusion test on Muller-Hinton agar to assess their antibiotic susceptibility patterns. Binary logistic regression analysis in Statistical Package for Social Sciences (SPSS) Version 25 was used to determine the strength of the risk factors associated with the occurrence of this disease. Findings: The overall prevalence of Salmonella isolates was 12.9% (30/232) across all samples. Among these, 11.5% (23/200) of the fecal samples from the study animals and 21.9% (7/32) of the bulk tank milk samples tested positive for this disease. A statistically significant association was observed between the presence of the Salmonella isolates and the age of the study animals, farm size, bedding, and udder washing practices. The isolates also showed the highest resistance to ampicillin (100%) and tetracycline (96.7%). Conversely, the isolates were most sensitive to ciprofloxacin (100%) and kanamycin (90%). Conclusions: Generally, the high presence of Salmonella isolates and its resistance to drugs pose significant economic and public health challenges. Thus, it is crucial to implement improved management practices and appropriate antibiotic therapies in the study dairy farms.

Occurrence and antimicrobial susceptibility of Salmonella enterica in milk along the supply chain, humans, and the environment in Woliata Sodo, Ethiopia

BACKGROUND

Salmonella enterica is a major cause of foodborne illness and mortality worldwide, but its presence in milk along the milk supply chain and associated public health risks are under-studied. This research was aimed to investigate the occurrence and antimicrobial susceptibility of Salmonella enterica in milk, milking environments, milkers' hands, and diarrheic patients in Wolaita Sodo, Ethiopia.

METHODS

We collected 644 samples from 106 dairy farms that include direct milk from cow, bulk tank milk, milkers' hand swabs, teat surfaces swabs, farm floors swabs, milk storage containers swabs, collectors' bulk milk, retailers' bulk milk, and stool from diarrheic patients. Salmonella enterica was isolated using standard microbiological methods (culture-based detection, serology and PCR), and antimicrobial susceptibility was tested using the Kirby-Bauer disk diffusion method against 14 antimicrobials.

RESULTS

The overall occurrence of Salmonella enterica was 1.86% (12/644). The detection rate was 2.06% (7/339: 95% CI: 1.0-4.20) along the milk supply chain, 1.94% (2/103:95% CI: 0.53-6.81) in diarrheic outpatients and 1.49% (3/202: 95% CI: 0.51-4.27) in the milking environments. Relatively, higher contamination rate (6%, 3/50; 95% CI: 2.06-16.22) was observed in milk samples collected from milk collectors. The isolates exhibit higher resistance to clindamycin (100%), erythromycin (100%), vancomycin (100%), amoxicillin (100%), ceftazidime (100%), and ampicillin (75%). Of the isolates, 92%, 83% and 67% were susceptible to norfloxacin, ciprofloxacin and Trimethoprim, respectively. All the isolates were multidrug resistant (MDR).

CONCLUSIONS

The study findings showed the occurrence of a considerable proportion of antimicrobial resistant Salmonella enterica across all sample sources, indicating potential transmission risks between cattle and humans via milk, and the milking environment. The alarming multidrug-resistant strains limit treatment options and complicate pathogen control. To prevent transmission and spread of antimicrobial resistant pathogen, proper hygiene practices, public education, and antimicrobial stewardship are essential. These measures will help ensure the safety of milk and dairy products. Further research on genetic relatedness among isolates, quantifying public health risks of milk consumption, and cost-effective intervention options is needed to reduce Salmonella-related morbidity and mortality.

Virulence, multiple drug resistance, and biofilm-formation in Salmonella species isolated from layer, broiler, and dual-purpose indigenous chickens

Globally, the significant risk to food safety and public health posed by antimicrobial-resistant foodborne Salmonella pathogens is driven by the utilization of in-feed antibiotics, with variations in usage across poultry production systems. The current study investigated the occurrence of virulence, antimicrobial resistant profiles, and biofilm-forming potentials of Salmonella isolates sourced from different chicken types. A total of 75 cloacal faecal samples were collected using sterile swabs from layer, broiler, and indigenous chickens across 15 poultry farms (five farms per chicken type). The samples were analysed for the presence of Salmonella spp. using species-specific PCR analysis. Out of the 150 presumptive isolates, a large proportion (82; 55%) were confirmed as Salmonella species, comprising the serovars S. typhimurium (49%) and S. enteritidis (30%) while 21% were uncategorised. Based on phenotypic antibiotic susceptibility test, the Salmonella isolates were most often resistant to erythromycin (62%), tetracycline (59%), and trimethoprim (32%). The dominant multiple antibiotic resistance phenotypes were SXT-W-TE (16%), E-W-TE (10%), AML-E-TE (10%), E-SXT-W-TE (13%), and AMP-AML-E-SXT-W-TE (10%). Genotypic assessment of antibiotic resistance genes revealed that isolates harboured the ant (52%), tet (A) (46%), sui1 (13%), sui2 (14%), and tet (B) (9%) determinants. Major virulence genes comprising the invasion gene spiC, the SPI-3 encoded protein (misL) that is associated with the establishment of chronic infections and host specificity as well as the SPI-4 encoded orfL that facilitates adhesion, autotransportation and colonisation were detected in 26%, 16%, and 14% of the isolates respectively. There was no significant difference on the proportion of Salmonella species and the occurrence of virulence and antimicrobial resistance determinants among Salmonella isolates obtained from different chicken types. In addition, neither the chicken type nor incubation temperature influenced the potential of the Salmonella isolates to form biofilms, although a large proportion (62%) exhibited weak to strong biofilm-forming potentials. Moderate to high proportions of antimicrobial resistant pathogenic Salmonella serovars were detected in the study but these did not vary with poultry production systems.

Antibiotic Resistance Profile of Salmonella sp. Isolates from Commercial Laying Hen Farms in Central-Western Brazil

Microbial resistance to antibiotics poses a significant threat to both human and animal health, necessitating international efforts to mitigate this issue. This study aimed to assess the resistance profiles of Salmonella sp. isolates and identify the presence of intl1, sul1, and blaTEM resistance genes within antigenically characterized isolates, including Agona, Livingstone, Cerro, Schwarzengrund, Salmonella enterica subsp. enterica serotype O:4.5, Anatum, Enteritidis, Johannesburg, Corvallis, and Senftenberg. These isolates underwent susceptibility testing against 14 antibiotics. The highest resistance percentages were noted for sulfamethoxazole (91%), sulfonamides (51%), and ceftiofur (28.9%), while no resistance was observed for ciprofloxacin. Salmonella Johannesburg and Salmonella Corvallis showed resistance to one antibiotic, whereas other serovars were resistant to at least two. Salmonella Schwarzengrund exhibited resistance to 13 antibiotics. The intl1 gene was detected in six out of the ten serovars, and the sul1 gene in three, always co-occurring with intl1. The blaTEM gene was not identified. Our findings highlight the risk posed by the detected multiple resistances and genes to animal, human, and environmental health. The multidrug resistance, especially to third-generation cephalosporins and fluoroquinolones, highlights the need for stringent monitoring of Salmonella in laying hens. The potential of the environment, humans, eggs, and their products to act as vectors for antibiotic resistance represents a significant concern for One Health.

A Systematic review on Prevalence, Serotypes and Antibiotic resistance of Salmonella in Ethiopia, 2010-2022

Background

In Ethiopia, salmonellosis is one of the most common zoonotic and foodborne illnesses. Ethiopia continues to be at risk for its fast-expanding medication resistance. For the development of preventative and control methods, summarized knowledge regarding salmonellosis is necessary. Determining a thorough evaluation of the prevalence, serotypes, and antibiotic resistance of Salmonella in humans and animals from January 1, 2010, to December 30, 2022, in Ethiopia was our goal.

Methods

To find Salmonella related articles that published in English, we used the Google Scholar and PubMed search engines. Three researchers conducted the eligible studies using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist, making sure to include the necessary keywords. If studies were duplicates, incomplete publications, or reported without an antimicrobial test were excluded. Excel 2013 was used to calculate frequencies and tabulate data.

Results

There were a total of 43 investigations from food handlers, diarrhoeic patients, and animals. The prevalence rates ranged from 1% to 10% and 1% to 13% among food handlers and diarrhoea patients, respectively. The highest prevalence was among pigs (41.6%). S. Anatum in animals and S. Typhimurium in people were the predominant serotypes. Amoxicillin and ampicillin were claimed to be 100% resistant in human studies. The highest recorded resistances for ceftriaxone and ciprofloxacin were 16.7% and 100%, respectively. Animal studies revealed that Salmonella resistances to ampicillin, streptomycin and tetracycline were 100%, 90%, 86.4%, respectively. S. Kentucky showed complete resistance to tetracycline, ampicillin, gentamicin, ciprofloxacin, and streptomycin.

Conclusion

The prevalence of Salmonella among asymptomatic food handlers, diarrheal patients and animals were high in Ethiopia. S. Typhimurium that have the zoonotic importance was presented predominantly in human study. High levels of resistances were showed to tetracycline, ampicillin and streptomycin in animal studies. Salmonellosis prevention and control techniques should be strengthened.

A South African Perspective on the Microbiological and Chemical Quality of Meat: Plausible Public Health Implications

Meat comprises proteins, fats, vitamins, and trace elements, essential nutrients for the growth and development of the body. The increased demand for meat necessitates the use of antibiotics in intensive farming to sustain and raise productivity. However, the high water activity, the neutral pH, and the high protein content of meat create a favourable milieu for the growth and the persistence of bacteria. Meat serves as a portal for the spread of foodborne diseases. This occurs because of contamination. This review presents information on animal farming in South Africa, the microbial and chemical contamination of meat, and the consequential effects on public health. In South Africa, the sales of meat can be operated both formally and informally. Meat becomes exposed to contamination with different categories of microbes, originating from varying sources during preparation, processing, packaging, storage, and serving to consumers. Apparently, meat harbours diverse pathogenic microorganisms and antibiotic residues alongside the occurrence of drug resistance in zoonotic pathogens, due to the improper use of antibiotics during farming. Different findings obtained across the country showed variations in prevalence of bacteria and multidrug-resistant bacteria studied, which could be explained by the differences in the manufacturer practices, handling processes from producers to consumers, and the success of the hygienic measures employed during production. Furthermore, variation in the socioeconomic and political factors and differences in bacterial strains, geographical area, time, climatic factors, etc. could be responsible for the discrepancy in the level of antibiotic resistance between the provinces. Bacteria identified in meat including Escherichia coli, Listeria monocytogenes, Staphylococcus aureus, Campylobacter spp., Salmonella spp., etc. are incriminated as pathogenic agents causing serious infections in human and their drug-resistant counterparts can cause prolonged infection plus long hospital stays, increased mortality and morbidity as well as huge socioeconomic burden and even death. Therefore, uncooked meat or improperly cooked meat consumed by the population serves as a risk to human health.

Salmonella Phages Affect the Intestinal Barrier in Chicks by Altering the Composition of Early Intestinal Flora: Association With Time of Phage Use

Phages show promise in replacing antibiotics to treat or prevent bacterial diseases in the chicken breeding industry. Chicks are easily affected by their environment during early growth. Thus, this study investigated whether oral phages could affect the intestinal barrier function of chicks with a focus on the cecal microbiome. In a two-week trial, forty one-day-old hens were randomly divided into four groups: (1) NC, negative control; (2) Phage 1, 10⁹ PFU phage/day (days 3–5); (3) Phage 2, 10⁹ PFU phage/day (days 8–10); and (4) AMX, 1 mg/mL amoxicillin/day (days 8–10). High-throughput sequencing results of cecal contents showed that oral administration of phages significantly affected microbial community structure and community composition, and increased the relative abundance of Enterococcus. The number of different species in the Phage 1 group was much higher than that in the Phage 2 group, and differences in alpha and beta diversity also indicated that the magnitude of changes in the composition of the cecal microbiota correlated with the time of phage use. Particularly in the first stage of cecal microbiota development, oral administration of bacteriophages targeting Salmonella may cause substantial changes in chicks, as evidenced by the results of the PICRUSt2 software function prediction, reminding us to be cautious about the time of phage use in chicks and to avoid high oral doses of phages during the first stage. Additionally, the Phage 2 samples not only showed a significant increase in the relative abundance of Bifidobacterium and Subdoligranulum, but also improved the intestinal morphology (jejunum) and increased the mRNA expression level of occludin and ZO-1. We concluded that phages do not directly interact with eukaryotic cells. The enhancement of intestinal barrier function by phages in chicks may be related to changes in the intestinal flora induced by phages. This implies that phages may affect intestinal health by regulating the intestinal flora. This study provides new ideas for phage prevention of intestinal bacterial infections and promotes large-scale application of phages in the poultry industry.