Isolation of Salmonella from poultry droppings and other environmental sources in Awka, Nigeria

Prevalence and serotype of poultry salmonellosis in Africa: a systematic review and meta-analysis

RESEARCH HIGHLIGHTS

The pooled sample prevalence of poultry salmonellosis in Africa is high (14.4%).The highest PPE was recorded in meat and meat products.Salmonella serotypes of zoonotic importance were found in all sample types.Salmonella Enteritidis and Typhimurium are common serotypes spreading in Africa.

Quantitative assessment of food safety interventions for Campylobacter spp. and Salmonella spp. along the chicken meat supply chain in Burkina Faso and Ethiopia

Rural and small-scale chicken farming is a major source of income in most African countries, and chicken meat is an important source of nutrients. However, chicken meat can be contaminated with Campylobacter spp. and Salmonella spp., pathogens with a high reported burden of foodborne illnesses. Therefore, it is essential to control these pathogens in chicken meat. Quantitative microbial risk assessments (QMRA) can aid the development of effective food safety control measures and are currently lacking in chicken meat supply chains in the African context. In this study, we developed stochastic QMRA models for Salmonella spp. and Campylobacter spp. in the chicken meat supply chain in Burkina Faso and Ethiopia employing the modular process risk model in @Risk software. The study scope covered chicken farming, transport, slaughtering, consumer handling, and consumption. Effectiveness of candidate interventions was assessed against baseline models' outputs, which showed that the mean annual Campylobacter spp. risk estimates were 6482 cases of illness per 100,000 persons and 164 disability adjusted life years (DALYs) per 100,000 persons in Burkina Faso, and 12,145 cases and 272 DALYs per 100,000 persons in Ethiopia. For Salmonella spp., mean annual estimates were 2713 cases and 1212 DALYs per 100,000 persons in Burkina Faso, and 4745 cases and 432 DALYs per 100,000 persons in Ethiopia. Combining interventions (improved hand washing plus designated kitchen utensils plus improved cooking) resulted in 75 % risk reduction in Burkina Faso at restaurants and 93 to 94 % in Ethiopia at homes for both Salmonella spp. and Campylobacter spp. For Burkina Faso, adding good hygienic slaughter practices at the market to these combined interventions led to over 91 % microbial risk reduction. Interventions that involved multiple food safety actions in a particular step of the supply chain or combining different interventions from different steps of the supply chain resulted in more risk reduction than individual action interventions. Overall, this study demonstrates how diverse and scanty food supply chain information can be applied in QMRA to provide estimates that can be used to stimulate risk-based food safety action in African countries.

An Alternative Approach Using Nano-garlic Emulsion and its Synergy with Antibiotics for Controlling Biofilm-Producing Multidrug-Resistant Salmonella in Chicken

Surface-growing antibiotic-resistant pathogenic Salmonella is emerging as a global health challenge due to its high economic loss in the poultry industry. Their pathogenesis, increasing antimicrobial resistance, and biofilm formation make them challenging to treat with traditional therapy. The identification of antimicrobial herbal ingredients may provide valuable solutions to solve this problem. Therefore, our aim is to evaluate the potency of nano garlic as the  alternative of choice against multidrug-resistant (MDR) Salmonella isolates using disc diffusion and microdilution assays. Then, checkerboard titration in trays was applied, and FIC was measured to identify the type of interaction between the two antimicrobials. A disc diffusion assay revealed that neomycin was the drug of choice. The range of nano garlic MIC was 12.5-25 μg/ml, while the neomycin MIC range was 32-64 μg/ml. The FIC index established a synergistic association between the two tested drugs in 85% of isolates. An experimental model was used including nano garlic and neomycin alone and in combination against Salmonella infection. The combination therapy significantly improved body productivity and inhibited biofilm formation by more than 50% down regulating the CsgBAD, motB, and sipA operons, which are responsible for curli fimbriae production and biofilm formation in Salmonella serotypes.

In Vitro Characterization of Probiotic Potential of Limosilactobacillus fermentum against Salmonella Gallinarum Causing Fowl Typhoid

Fowl typhoid, a septicaemic disease of poultry, is caused by Salmonella Gallinarum and leads to severe economic losses. The aim of the present study was to isolate, select and characterize indigenous probiotic lactobacilli with anti-Salmonella Gallinarum activity. A total 55 lactobacilli were isolated from the caeca and ileum parts of healthy chickens and identified to species level by 16S rDNA sequencing. All the isolates were initially screened for antimicrobial activity and selected isolates were further subjected to in vitro evaluation of probiotic properties. Lactobacilli isolates (n = 21) showed varying levels of activity (08-18 mm) against Salmonella Gallinarum. These selected isolates also showed tolerance to acidic conditions (pH 3 and 4). Out of these 21 isolates, 13 showed growth (>0.5 OD at 600 nm) 0.3% bile salts. Moreover, these isolates also had the ability of auto-aggregation (20.05 ± 0.62%-50.70 ± 1.40%), and co-aggregation with Salmonella Gallinarum (5.22 ± 0.21%-42.07 ± 0.70%). Results revealed that lactobacilli had a higher level of resistance to vancomycin (100%), streptomycin (100%), ciprofloxacin (95%), gentamicin (90%), doxycycline (90%), oxytetracycline (85%), and bacitracin (80%), and a lower level of resistance to penicillin (33%), erythromycin (28%), chloramphenicol (23%), fusidic acid (23%) and amoxicillin (4%). The Limosilactobacillus fermentum PC-10 and PC-76 were sensitive to most of the antibiotics. The overall results revealed that two Limosilactobacillus fermentum strains (PC-10 and PC-76) fulfill the in vitro selection criteria of probiotics, i.e, tolerance to low pH, resistance to bile salts, auto-aggregation, co-aggregation with Salmonella Gallinarum, and absence of acquired antibiotic resistance. The Limosilactobacillus fermentum PC-10 and PC-76 also inhibited the (>5 log10) growth of Salmonella Gallinarum in co-culture assay. It is concluded that Limosilactobacillus fermentum PC-10 and PC-76 may be further investigated and developed as anti-Salmonella Gallinarum probiotics for poultry.

Prevalence and Antimicrobial Resistance of Salmonella in Poultry Products in Central Ethiopia

Salmonellosis is a bacterial infection caused by salmonella, a member of the Enterobacteriaceae family. From December 2021 to May 2021, a cross-sectional study was carried out to isolate Salmonella from poultry farms in the towns of Bishoftu and Adama and to determine the antimicrobial susceptibility frequency of the isolates. A total of 384 samples were tested for the presence of Salmonella, including 259 feces, 56 eggs, and 69 types of meat, using the ISO, 2002 standard procedures. The raw data were organized, coded, and entered into an Excel spreadsheet before being analyzed with STATA via descriptive analysis with chi-square. From 384 collected samples, 62 (16.15%) isolates were obtained, with 9.9%, 3.65, and 2.6% found in feces, eggs, and meat, respectively. Statistically, there was a significant difference between breeds (p value = 0.036). Bovines had the highest prevalence (32.83%), while Saso had the lowest (30.81%). The variation within each sample type, housing condition, and age group was not statistically significant (p value >0.05). Antimicrobial resistance was found in 29 (96.77%) of the isolates. Ampicillin and sulphamethoxazole-trimethoprim were effective against all isolates. Salmonella was isolated from various locations, sample types, ages, and breeds, indicating a wider distribution. Salmonellosis detection isolates suggested that it could be an emerging poultry and public health issue. As a result, future research should concentrate on isolating and identifying salmonella from poultry in backyard systems and comparing it to that of an intensive farm, as well as molecular characterization for serotyping and genetic studies, as well as genes responsible for salmonella pathogenicity and drug resistance.

CRISPR-Cas System: An Adaptive Immune System’s Association with Antibiotic Resistance in Salmonella enterica Serovar Enteritidis

Several factors are involved in the emergence of antibiotic-resistant bacteria and pose a serious threat to public health safety. Among them, clustered regularly interspaced short palindromic repeat- (CRISPR-) Cas system, an adaptive immune system, is thought to be involved in the development of antibiotic resistance in bacteria. The current study was aimed at determining not only the presence of antibiotic resistance and CRISPR-Cas system but also their association with each other in Salmonella enteritidis isolated from the commercial poultry. A total of 139 samples were collected from poultry birds sold at the live bird markets of Lahore City, and both phenotypic and genotypic methods were used to determine antimicrobial resistance. The presence of the CRISPR-Cas system was determined by PCR, followed by sequencing. All isolates of S. enteritidis (100%) were resistant to nalidixic acid, whereas 95% of isolates were resistant to ampicillin. Five multidrug-resistant isolates (MDR) such as S. enteritidis isolate (S. E1, S. E2, S. E4, S. E5, and S. E8) were found in the present study. The CRISPR-Cas system was detected in all of these MDR isolates, and eight spacers were detected within the CRISPR array. In addition, an increased expression of CRISPR-related genes was observed in the standard strain and MDR S. enteritidis isolates. The association of the CRISPSR-Cas system with multiple drug resistance highlights the exogenous acquisition of genes by horizontal transfer. The information could be used further to combat antibiotic resistance in pathogens like Salmonella.

Antimicrobial resistance and virulence genes in Salmonella enterica serovars isolated from droppings of layer chicken in two farms in Nigeria

AIM

This study aimed to investigate the isolation rate, antibiotic resistance, and virulence genes of Salmonella enterica serovar from two commercial farms in Nigeria.

METHODS AND RESULTS

Salmonella isolation was performed according to the United States Food and Drug Agency (USFDA) method. Serotyping, antimicrobial susceptibility testing, detection of resistance and virulence genes were done using the Kauffman-White Scheme, disc diffusion, minimum inhibitory concentration, and real-time polymerase chain reaction techniques. Salmonella serovars were isolated from only farm A at 22/50 (44.0%) while none were isolated from farm B. Salmonella Typhi, 9 (40.9%); Salmonella Typhimurium, 2 (9.1%), Salmonella Enteritidis, 2 (9.1%), Salmonella Pullorum, 1 (4.5%), Salmonella Kentucky, 4 (18.2%) were identified while 4 (18.2%) were untypable. Sixteen isolates (72.7%) showed multiple drug resistance and 17 different resistance profile types with AMP-CHL-TRM-SXT as the most prevalent pattern. Resistance genes (blaTEM, 12/22 (54.5%) and virulence genes (InvA, sopB, mgtC, and spi4D, 22/22 (100.0%), ssaQ, 16/22 (72.7%), and spvC, 13/22 (59.1%) were found, while blaSHV, blaCTX-M, floR, tetA, tetB, tetG, and LJSGI-1 genes were absent.

CONCLUSION

Pathogenic Salmonella were isolated from the chicken droppings in this study. Most of these strains were resistant to antibiotics and possessed characteristics of virulence.

SIGNIFICANCE AND IMPACT OF THE STUDY

Chicken droppings from this study area contained pathogenic strains of Salmonella and a rare occurrence of Salmonella Typhi. The study revealed that the environment and the food chain could be at risk of contamination of highly virulent and antimicrobial-resistant strains of Salmonella. These could affect the profitability of the poultry industry and food consumption. There is a need for caution in indiscriminate disposal of poultry waste and the use of uncomposted chicken droppings in soil amendment.

Examination of Australian backyard poultry for Salmonella, Campylobacter and Shigella spp., and related risk factors

Worldwide, foodborne illness is a significant public health issue in both developed and developing countries. Salmonellosis, campylobacteriosis and shigellosis are common foodborne gastrointestinal illnesses caused by the bacteria Salmonella spp., Campylobacter spp. and Shigella spp. respectively. These zoonotic diseases are frequently linked to eggs and poultry products. The aim of this study was to investigate the presence of these pathogens in Australian backyard poultry flocks and to determine risk factors for these pathogens. Poultry faeces samples were collected from 82 backyards and screened for Salmonella spp., Campylobacter spp. and Shigella spp. using qPCR. A questionnaire was administered to the backyard poultry owners to assess their knowledge regarding management of poultry and eggs and to identify potential risk factors that may contribute to the presence of zoonotic pathogens in the flocks. One composite faecal sample was collected from each backyard (82 samples). Composite sampling here means taking one or more grab samples from a backyard to make up approximately 10 grams. Four per cent of samples, that is 4% backyards tested, were positive for Salmonella spp., 10% were positive for Campylobacter spp. and none were positive for Shigella spp. A higher infection rate was seen in multi-aged flocks (24%) compared with the single-aged flocks (3%). The survey found that many participants were engaging in risky food safety behaviours with 46% of participants responding that they washed their eggs with running water or still water instead of wiping the dirt off with a damp cloth to clean the eggs and 19% stored their eggs at room temperature. This study demonstrated that backyard poultry may pose a potential risk for salmonellosis and campylobacteriosis. Additionally, Australian public health and food safety regulations should be modified and effectively implemented to address the risks associated with backyard poultry husbandry.

Multilocus sequence typing of multidrug-resistant Salmonella strains circulating in poultry farms of Bangladesh

Salmonella is one of the most important foodborne zoonotic pathogens, and becoming multidrug-resistant (MDR), which represents a serious public health concern worldwide. This study aimed to identify the circulating MDR strains of Salmonella through cutting edge molecular techniques including gene specific PCR, RAPD-PCR, ribosomal gene sequencing, and multilocus sequence types (MLST) in the poultry industry of Bangladesh. Two hundred Salmonella isolates were retrieved from 154 samples comprising droppings (n = 60), cloacal swabs (n = 60), feeds (n = 14), feeding water (n = 14), and handler's swab (n = 6) from 14 commercial layer farms of Bangladesh. The isolates were confirmed as Salmonella through invA gene specific PCR, and further genotyping was done by RAPD-PCR, and 16S rRNA sequencing. The isolates were distributed into 18 different genotypes according to RAPD typing. The phylogenetic analysis identified three diverging phylogroups such as S. enterica Litchfield, S. enterica Enteritidis and S. enterica Kentucky with 11, 8, and 6 strains, respectively. The in vitro antibiogram profiling the Salmonella isolates through disc diffusion method using 13 commercially available antibiotics revealed highest resistance against doxycycline (91.5%) followed by tetracycline and ampicillin (86.0%, in each), and 72.0% isolates as MDR, being resistant to ≥ 5 antibiotics. The MLST typing was carried out based on the PCR amplification of seven housekeeping genes (aroC, hisD, hemD, purE, secA, thrA, and dnaN). MLST typing also revealed three sequence types (STs) such as ST11, ST198, and ST214 in these isolates, and eBURST analysis showed ST11 as the founder genotype. The three STs were highly resistant to tetracyclines and quinolone group of antibiotics, and all of the isolates harboring S. enterica Litchfield showed the highest resistance. Circulating common MLSTs with MDR properties in different farms confirmed the possibility of a common route of intra-farm transmission. We report for the first time of the association serovar Litchfield (ST11) in avian salmonellosis with MDR properties which is an urgent public health concern in Bangladesh.

Salmonella Characterization in Poultry Eggs Sold in Farms and Markets in Relation to Handling and Biosecurity Practices in Ogun State, Nigeria

Salmonella remains one of the notable food-borne bacterial pathogens. It is associated with poultry and poultry products including eggs. This study investigated Salmonella distribution in eggshell and content, their antimicrobial resistance pattern, and the possible risk factors driving contamination in Ogun State, Nigeria. A total of 500 eggs (5 eggs pooled into one sample) were collected and culturally examined for the presence of Salmonella serovars. Isolates were further characterized biochemically using Microbact 20E (Oxoid) and Antimicrobial susceptibility determined by the Kirby-Bauer disk diffusion method. A total of 14 Salmonella isolates spread across 10 serovars were recovered from the 100 pooled egg samples; 10 (10%) from the market and 4 (4%) farms, 13(13%) eggshell, and 1(1%) egg content. All tested serovars were susceptible to ampicillin, chloramphenicol, florfenicol, and kanamycin. Resistance was mostly observed in sulfamethoxazole 8 (80%), followed by ciprofloxacin 5 (50%) and tetracycline 3 (30%). Sales of eggs in the market appear to be a strong factor encouraging contamination in addition to poor biosecurity and unhygienic handling of eggs on the farm.

Characterization of non-typhoidal Salmonella from poultry in Punjab, India

Present study was done to determine the prevalence, virulence and antimicrobial spectrum of identified serotypes. A total of 693 samples, comprising 585 poultry fecal samples (420 from layer, 120 from broiler and 45 from backyard poultry), 54 each poultry feed and farm water were collected from 31 poultry farms of three districts of Punjab. A total of 6 Salmonella isolates were obtained from these samples. Out of 585 fecal samples, 6 (1.02%) were positive for Salmonella. Out of 31 farms, 2 (6.45%) farms were positive for Salmonella. Out of 6 Salmonella isolates, four isolates from one farm were serotype Salmonella IIIa, 35: z24: z23 and two Salmonella isolates from another farm were untypable and also carried spvC gene. Isolates showed resistance to gentamicin (2/6, 33.3%), co-trimoxazole (1/6, 16.7%). Antibiotics ampicillin, tetracycline, ciprofloxacin, chloramphenicol and enrofloxacin were effective against all the isolates. On PFGE analysis, four isolates from one farm were clustered in two clusters and two isolates from other farm were similar and clustered together. Based on the results we can say that drug resistant Salmonella is present in poultry flock in Punjab.

Molecular detection of virulence genes in Salmonella spp. isolated from chicken faeces in Mafikeng, South Africa

Chickens have been implicated in most Salmonella disease outbreaks because they act as carriers of the pathogen in their gut. There are over 2500 serotypes of Salmonella that have been reported worldwide and 2000 of these serovars can be found in chickens. The main objective of this study was to determine the Salmonella serotypes found in poultry farms around Mafikeng district, South Africa. Salmonella was identified according to the guidelines of the International Organization for Standardization (ISO) (ISO 6579:2002) standard techniques. Faecal samples were collected and analysed for Salmonella using conventional cultural methods and polymerase chain reaction targeting the 16S Ribosomal Deoxyribonucleic acid (rDNA) gene for Salmonella identification. Out of 130 presumptive Salmonella isolates determined by urease and triple sugar iron tests, only 46 isolates were identified as Salmonella serotypes of which S. Typhimurium was the most frequent with 18 (39.1%), followed by S. Heidelberg with 9 (19.6%), S. bongori with 7 (15.2%), S. Enteritidis with 6 (13.0%) and both S. Paratyphi B and S. Newport with 3 (6.5%) each. Seven virulence genes including invA 100%, spy 39%, hilA 9%, misL 30%, sdfI 13%, orfL 11% and spiC 9% were detected from these Salmonella isolates in this study. The presence of these virulence genes indicates high pathogenicity potential of these isolates which is a serious public health concern because of zoonotic potential of Salmonella.

Prevalence of Campylobacter and Salmonella in African food animals and meat: A systematic review and meta-analysis

BACKGROUND

Campylobacter and Salmonella, particularly non-typhoidal Salmonella, are important bacterial enteric pathogens of humans which are often carried asymptomatically in animal reservoirs. Bacterial foodborne infections, including those derived from meat, are associated with illness and death globally but the burden is disproportionately high in Africa. Commercial meat production is increasing and intensifying in many African countries, creating opportunities and threats for food safety.

METHODS

Following Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines, we searched six databases for English language studies published through June 2016, that reported Campylobacter or Salmonella carriage or infection prevalence in food animals and contamination prevalence in food animal products from African countries. A random effects meta-analysis and multivariable logistic regression were used to estimate the species-specific prevalence of Salmonella and Campylobacter and assess relationships between sample type and region and the detection or isolation of either pathogen.

RESULTS

Seventy-three studies reporting Campylobacter and 187 studies reporting Salmonella across 27 African countries were represented. Adjusted prevalence calculations estimate Campylobacter detection in 37.7% (95% CI 31.6-44.3) of 11,828 poultry samples; 24.6% (95% CI 18.0-32.7) of 1975 pig samples; 17.8% (95% CI 12.6-24.5) of 2907 goat samples; 12.6% (95% CI 8.4-18.5) of 2382 sheep samples; and 12.3% (95% CI 9.5-15.8) of 6545 cattle samples. Salmonella were detected in 13.9% (95% CI 11.7-16.4) of 25,430 poultry samples; 13.1% (95% CI 9.3-18.3) of 5467 pig samples; 9.3% (95% CI 7.2-12.1) of 2988 camel samples; 5.3% (95% CI 4.0-6.8) of 72,292 cattle samples; 4.8% (95% CI 3.6-6.3) of 11,335 sheep samples; and 3.4% (95% CI 2.2-5.2) of 4904 goat samples. 'External' samples (e.g. hide, feathers) were significantly more likely to be contaminated by both pathogens than 'gut' (e.g. faeces, cloaca) while meat and organs were significantly less likely to be contaminated than gut samples.

CONCLUSIONS

This study demonstrated widespread prevalence of Campylobacter species and Salmonella serovars in African food animals and meat, particularly in samples of poultry and pig origin. Source attribution studies could help ascertain which food animals are contributing to human campylobacteriosis and salmonellosis and direct potential food safety interventions.

Identification and characterization of Salmonella spp. from samples of broiler farms in selected districts of Bangladesh

Background and Aim:

Salmonella spp. are an important group of pathogens responsible for human and animal diseases. This study aimed to estimate the prevalence and identify and characterize of Salmonella spp. isolated from broiler farms of Gazipur, Tangail, and Dhaka districts of Bangladesh. This study also evaluated the difference of Salmonella positivity status between two groups of farms, good practices adapted in broiler rearing at the project intervened farms, and non-project intervened traditional farms.

Materials and Methods:

A total of 352 samples including 128 cloacal swabs, 32 whole carcasses, 64 feed, 64 water, and 64 attendants’ hand rinses were collected through convenient sampling technique from 16 poultry food safety project of Food and Agricultural Organization of United Nations Bangladesh intervened farms and other 16 non-project intervened farms in the same location. Various cultural based techniques and biochemical methods were employed for the estimation of prevalence, isolation, and identification of Salmonella spp. which was further evaluated by polymerase chain reaction. Antimicrobial susceptibility test using disk diffusion methods and serogrouping by slide agglutination test was accomplished for additional characterization.

Results:

Among the samples, an overall prevalence of Salmonella spp. was 31.25% (110/352) (95% confidence interval [CI]=26.44-36.38%). However, the prevalence of Salmonella spp. was 24.43% (43/176) (95% CI=18.28-31.47) in project intervened farms and 38.07% (67/176) (95% CI=30.87-45.68%) in non-intervened farms. Among the 110 isolates, 31.82% (35/110) were fitted under serogroup B, and the rest of the isolates 75 (68.18%) under serogroup D. Of 110 isolates, 82.72%, 77.27%, 81.82%, and 79.09% were susceptible to ciprofloxacin, gentamycin, norfloxacin, and streptomycin, respectively. In addition, 81.82% and 80% isolates were resistant to erythromycin and tetracycline, respectively. Isolated Salmonella spp. presented moderate resistance to both amoxicillin and azithromycin. Alarmingly, 80.91% (89/110) isolates were shown to be multidrug-resistant Salmonella spp.

Conclusion:

The study has presented a significant variation of the prevalence of Salmonella spp. between project intervened and non-project intervened farms, and this indicates project intervened farms are comparatively safer than the non-intervened farms considering public health and food safety grounds. This research outcome also has highlighted a substantial proportion of poultry origin multidrug resistance Salmonella spp. is a potential source of public health hazards. In this regard, proper awareness creation and motivational activities on good agriculture practices in poultry rearing and maintaining good personal hygiene at the farmers’ level are warranted through participatory training.

Evaluation of a Salmonella Strain Isolated from Honeybee Gut as a Potential Live Oral Vaccine Against Lethal Infection of Salmonella Typhimurium

In this research, Salmonella species were isolated from the animal, insect and human enteric sources in Faisalabad, Punjab, Pakistan. These species were characterized by different microbiological and molecular techniques including polymerase chain reaction (PCR) by amplification of the 16S rRNA gene. Furthermore, sequencing of the amplicons confirmed all ten isolates as Salmonella strains. The antigenic cross-reactivity was found maximum between the HB1 (strain isolated from honeybee) antiserum and its antigen with an antibody titer of 1:128, while the HB1 antiserum showed a cross-reactive titer range of 1:8 to 1:64. On the basis of the highest geometric mean titer (GMT) shown by the antiserum of the HB1 antigen, it was selected as the best candidate for a cross-reactive live Salmonella oral antigen. Moreover, the HB1 antigen was used a live oral antigen (1 × 10¹⁰ CFU/ml) in a safety test in rabbits and proved to be avirulent. During the animal trial, three different oral doses of the HB1 live oral antigen were evaluated in four different rabbits' groups (R1, R2, R3, and R4). The dose number 2 of 0.5 ml (two drops orally and repeated after one week) gave the best GMT measured by indirect hemagglutination (IHA) as compared to the other two doses, while R4 group was kept as control. Results of the challenge protection test also validated the efficacy of the double dose of the HB1 live vaccine, which gave the highest survival percentage. Results of this study lay the foundation for a potential cross-reactive live oral Salmonella vaccine that has proved to be immunogenic in rabbits.

In this research, Salmonella species were isolated from the animal, insect and human enteric sources in Faisalabad, Punjab, Pakistan. These species were characterized by different microbiological and molecular techniques including polymerase chain reaction (PCR) by amplification of the 16S rRNA gene. Furthermore, sequencing of the amplicons confirmed all ten isolates as Salmonella strains. The antigenic cross-reactivity was found maximum between the HB1 (strain isolated from honeybee) antiserum and its antigen with an antibody titer of 1:128, while the HB1 antiserum showed a cross-reactive titer range of 1:8 to 1:64. On the basis of the highest geometric mean titer (GMT) shown by the antiserum of the HB1 antigen, it was selected as the best candidate for a cross-reactive live Salmonella oral antigen. Moreover, the HB1 antigen was used a live oral antigen (1 × 10¹⁰ CFU/ml) in a safety test in rabbits and proved to be avirulent. During the animal trial, three different oral doses of the HB1 live oral antigen were evaluated in four different rabbits’ groups (R1, R2, R3, and R4). The dose number 2 of 0.5 ml (two drops orally and repeated after one week) gave the best GMT measured by indirect hemagglutination (IHA) as compared to the other two doses, while R4 group was kept as control. Results of the challenge protection test also validated the efficacy of the double dose of the HB1 live vaccine, which gave the highest survival percentage. Results of this study lay the foundation for a potential cross-reactive live oral Salmonella vaccine that has proved to be immunogenic in rabbits.

Evaluation of a Salmonella Strain Isolated from Honeybee Gut as a Potential Live Oral Vaccine Against Lethal Infection of Salmonella Typhimurium

In this research, Salmonella species were isolated from the animal, insect and human enteric sources in Faisalabad, Punjab, Pakistan. These species were characterized by different microbiological and molecular techniques including polymerase chain reaction (PCR) by amplification of the 16S rRNA gene. Furthermore, sequencing of the amplicons confirmed all ten isolates as Salmonella strains. The antigenic cross-reactivity was found maximum between the HB1 (strain isolated from honeybee) antiserum and its antigen with an antibody titer of 1:128, while the HB1 antiserum showed a cross-reactive titer range of 1:8 to 1:64. On the basis of the highest geometric mean titer (GMT) shown by the antiserum of the HB1 antigen, it was selected as the best candidate for a cross-reactive live Salmonella oral antigen. Moreover, the HB1 antigen was used a live oral antigen (1 × 10¹⁰ CFU/ml) in a safety test in rabbits and proved to be avirulent. During the animal trial, three different oral doses of the HB1 live oral antigen were evaluated in four different rabbits’ groups (R1, R2, R3, and R4). The dose number 2 of 0.5 ml (two drops orally and repeated after one week) gave the best GMT measured by indirect hemagglutination (IHA) as compared to the other two doses, while R4 group was kept as control. Results of the challenge protection test also validated the efficacy of the double dose of the HB1 live vaccine, which gave the highest survival percentage. Results of this study lay the foundation for a potential cross-reactive live oral Salmonella vaccine that has proved to be immunogenic in rabbits.

Salmonellosis: Serotypes, prevalence and multi-drug resistant profiles of Salmonella enterica in selected poultry farms, Kwara State, North Central Nigeria

Salmonellosis is a major threat facing the poultry industry globally. This study was conducted to investigate the level of Salmonella contaminations and determine the resistance pattern of isolates obtained from selected poultry farms in Kwara State, a transition state between southern and northern regions of Nigeria. A total of 900 samples were collected between January and August 2017, from the poultry environment, apparently including healthy and dead birds. Salmonella was isolated and identified using standard bacteriological methods. All presumptive Salmonella isolates were serotyped and tested for antimicrobial susceptibility using 11 different antimicrobials. A total of 58 (6.4%) Salmonella isolates were obtained, and the isolation rate was only statistically significant (p < 0.05) in live birds. The isolates comprised of 13 serovars. The three predominant serovars, Salmonella enterica ser. 6.7:d:- (29.0%), Salmonella Agama (28.0%) and Salmonella Typhimurium (16.0%), were isolated from all three sample types. Rare serovars like Salmonella Albany, Salmonella Colindale, Salmonella Istanbul, Salmonella Larochelle, Salmonella Nigeria and Salmonella Orion were also isolated in this study. A high frequency of resistance was generally observed with all the isolates exhibiting a total of (100%) resistance to ampicillin, cefotaxime and ceftazidime. This study documents the first predominant isolation of S. enterica ser. 6.7:d:- and S. Agama from chickens. It also documents the high frequency of fluoroquinolone and cephalosporins resistance of the isolates indicating the presence of selective pressure in the environment. Controls and targeted interventions against Salmonella and the frequent occurrence of antimicrobial resistance in chickens should be initiated to prevent the spread of this organism.

Prevalence, antimicrobial susceptibility and risk factors associated with non-typhoidal Salmonella on Ugandan layer hen farms

BACKGROUND

Non-typhoidal Salmonella (NTS) are among the leading global foodborne pathogens and a significant public health threat. Their occurrence in animal reservoirs and their susceptibilities to commonly used antimicrobials are poorly understood in developing countries. The aim of this study was to estimate the prevalence, determine antimicrobial susceptibility and identify risk factors associated with NTS presence in laying hen farms in Uganda through a cross-sectional study.

RESULTS

Pooled faecal samples were collected from 237 laying hen farms and these were analysed for NTS following standard laboratory procedures. In total, 49 farms (20.7%; 95% Confidence interval (CI): 15.6-25.6%) were positive for NTS presence. Altogether, ten Salmonella serotypes were identified among the confirmed 78 isolates, and the predominant serotypes were Salmonella Newport (30.8%), S. Hadar (14.1%), S. Aberdeen (12.8%), S. Heidelberg (12.8%), and S. Bolton (12.8%). Phenotypic antimicrobial resistance was detected in 45(57.7%) of the isolates and the highest resistance was against ciprofloxacin (50.0%) followed by sulphonamides (26.9%) and sulphamethoxazole/trimethoprim (7.7%). Resistance was significantly associated with sampled districts (p = 0.034). Resistance to three or more drugs, multi-drug resistance (MDR) was detected in 12 (15.4%) of the isolates, 9 (75%) of these were from Wakiso district. A multivariable logistic model identified large farm size (OR = 7.0; 95% CI: 2.5-19.8) and the presence of other animal species on the farm (OR = 5.9; 95% CI: 2.1-16.1) as risk factors for NTS prevalence on farms. Having a separate house for birds newly brought to the farms was found to be protective (OR = 0,4; 95% CI: 0.2-0.8).

CONCLUSION

This study has highlighted a high prevalence and diversity of NTS species in laying hen farms in Uganda and identified associated risk factors. In addition, it has demonstrated high levels of antimicrobial resistance in isolates of NTS. This could be because of overuse or misuse of antimicrobials in poultry production. Also importantly, the insights provided in this study justifies a strong case for strengthening One Health practices and this will contribute to the development of NTS control strategies at local, national and international levels.

Salmonella serovars and their distribution in Nigerian commercial chicken layer farms

Commercial poultry farms (n° 523), located in all the six regions of Nigeria were sampled with a view to generate baseline information about the distribution of Salmonella serovars in this country. Five different matrices (litter, dust, faeces, feed and water) were collected from each visited farm. Salmonella was isolated from at least one of the five matrices in 228 farms, with a farm prevalence of 43.6% (CI95[39.7-48.3%]). Altogether, 370 of 2615 samples collected (14.1%, CI95[12.8; 15.5%]) contained Salmonella. Considering the number of positive farms and the number of positive samples, it was evident that for the majority of the sampled farms, few samples were positive for Salmonella. With regard to the matrices, there was no difference in Salmonella prevalence among the five matrices considered. Of the 370 isolates serotyped, eighty-two different serotypes were identified and Salmonella Kentucky was identified as having the highest isolation rate in all the matrices sampled (16.2%), followed by S. Poona and S. Elisabethville. S. Kentucky was distributed across the country, whereas the other less frequent serovars had a more circumscribed diffusion. This is one of few comprehensive studies on the occurrence and distribution of Salmonella in commercial chicken layer farms from all the six regions of Nigeria. The relatively high prevalence rate documented in this study may be attributed to the generally poor infrastructure and low biosecurity measures in controlling stray animals, rodents and humans. Data collected could be valuable for instituting effective intervention strategies for Salmonella control in Nigeria and also in other developing countries with a similar poultry industry structure, with the final aim of reducing Salmonella spread in animals and ultimately in humans.

Food safety management systems performance in African food processing companies: a review of deficiencies and possible improvement strategies

This study seeks to provide insight into current deficiencies in food safety management systems (FSMS) in African food-processing companies and to identify possible strategies for improvement so as to contribute to African countries' efforts to provide safe food to both local and international markets. This study found that most African food products had high microbiological and chemical contamination levels exceeding the set (legal) limits. Relative to industrialized countries, the study identified various deficiencies at government, sector/branch, retail and company levels which affect performance of FSMS in Africa. For instance, very few companies (except exporting and large companies) have implemented HACCP and ISO 22000:2005. Various measures were proposed to be taken at government (e.g. construction of risk-based legislative frameworks, strengthening of food safety authorities, recommend use of ISO 22000:2005, and consumers' food safety training), branch/sector (e.g. sector-specific guidelines and third-party certification), retail (develop stringent certification standards and impose product specifications) and company levels (improving hygiene, strict raw material control, production process efficacy, and enhancing monitoring systems, assurance activities and supportive administrative structures). By working on those four levels, FSMS of African food-processing companies could be better designed and tailored towards their production processes and specific needs to ensure food safety.

The first attempt of an active integrated laboratory-based Salmonella surveillance programme in the north-eastern region of Nigeria

AIM

To identify the sources of Salmonella contamination, distribution, prevalence and antimicrobial susceptibility patterns, which have significant impact on public and animal health, and international trade.

METHODS AND RESULTS

A total of 1888 samples were collected by stratified random sampling from 2009 to 2011 from cattle, camels, poultry, fish, vegetables and humans. All identified Salmonella isolates were serotyped and tested for antimicrobial susceptibility by MIC determinations. A total of 149 Salmonella isolates comprising 17 different serovars were obtained (7·9% prevalence). Salmonella Hadar (37%), S. Eko (17%), S. Enteritidis (10%), S. Kentucky (7%) and S. Uganda (7%) were isolated from different sources. The occurrence of antimicrobial resistance was generally low, but S. Enteritidis and S. Eko showed variable antimicrobial resistance patterns, while all S. Kentucky isolates were resistant to seven of 17 tested antimicrobials, including ciprofloxacin and nalidixic acid. Three S. Hadar isolates revealed reduced susceptibility to ciprofloxacin and susceptibility to nalidixic acid and harboured the plasmid-mediated quinolone resistance gene qnrS1.

CONCLUSIONS

Salmonella serovars Hadar, Enteritidis and the previously very rarely reported Eko were the major serovars associated with human infections, animal and environmental contamination in the north-eastern region of Nigeria.

SIGNIFICANCE AND IMPACT OF THE STUDY

These serovars constitute a health risk to poultry, environment and human population in the region.

Occurrence and antimicrobial resistance profiles of Salmonella species in retail meat products

In the present study, a total of 225 retail meat products (poultry meat, ground beef, and beef samples) were tested for the prevalence of Salmonella. Of these, 50 (22.2%) were positive for Salmonella. Overall, the pathogen was detected in 22 (29.3%) samples of poultry meat (n = 75), 16 (21.3%) samples of ground beef (n = 75), and 12 (16%) samples of beef (n = 75). The most common isolate was Salmonella enterica serovar Typhimurium (9.8%), followed by S. bongori species (8.9%) and S. enterica subsp. diarizonae (3.5%). The Salmonella strains isolated were also examined for antimicrobial resistance patterns and production of β-lactamase enzyme. The resistance levels of the isolates against 14 different antimicrobial agents were tested by the disk diffusion method. None of the strains exhibited resistance to cefotaxime, ciprofloxacin, norfloxacin, or levofloxacin. However, the highest resistance rates in the meat isolates were 64% each for ampicillin and cephazolin and 56% for amoxicillin-clavulanic acid. A total of 62% of the 50 Salmonella strains were multiresistant to three or more antimicrobial agents. The exhibited multiple resistance to four or more antimicrobial drugs was 32%. Furthermore, none of the isolates had β-lactamase enzyme activity.

Changes in antimicrobial resistance among Salmonella enterica subspecies enterica serovar Pullorum isolates in China from 1962 to 2007

There are few data available for the trends of antimicrobial resistance of Salmonella enterica subspecies enterica serovar Pullorum (S. Pullorum) in China and other parts of the world. Thus, the objective of this study was to evaluate the changes in antimicrobial resistance of S. Pullorum isolated from diseased chickens in China from 1962 to 2007. A total of 450 S. Pullorum isolates were tested for their susceptibility to 17 antimicrobials in a disk diffusion method. 39-95% of the isolates displayed a high level of resistance, particularly against ampicillin, carbenicillin, streptomycin, tetracycline, trimethoprim and sulfafurazole. Isolates exhibited increased resistance to carbenicillin, spectinomycin, trimethoprim, trimethoprim/sulfamethoxazole and nalidixic acid during the study period. Moreover, 56.2% of the isolates exhibited multiple drug resistance (MDR; resistance> or =4 antimicrobials) and showed an increasing trend between 1970-1979 and 2000-2007. Therefore, the results suggest that certain measures, including continued surveillance of antimicrobial resistance and the rational use of antimicrobials, are necessary and important in order to control the rapid increase in antimicrobial resistance in S. Pullorum.

An allele-specific PCR assay for the rapid and serotype-specific detection of Salmonella pullorum

Salmonella serovar Pullorum is a causative agent of pullorum disease (PD) in poultry and is responsible for severe economic losses to the poultry industry in many parts of the world. A definitive detection of Pullorum requires culture followed by serotyping and biochemical identification, a process that is tedious and takes several weeks to accomplish. We have developed a rapid allele-specific polymerase chain reaction (PCR) method based on the nucleotide polymorphism in rfbS gene sequence for the serotype-specific detection of Pullorum and its differentiation from the closely related Gallinarum. The specificity of this PCR assay was tested using DNA samples from Pullorum (n = 13), Salmonella serotypes other than Pullorum (n = 19), and closely related non-Salmonella organisms (n = 5). The PCR assay was highly serotype-specific as the PCR amplicon of 147 base pairs was observed only in the case of Pullorum, while all the other DNA samples tested PCR negative. A definitive identification of Pullorum cultures was possible in less than 3 hr. As little as 100 pg of SP DNA was detected. This allele-specific PCR method is highly specific as well as sensitive and may be an effective molecular tool in the rapid and serotype-specific detection of Pullorum and differentiation from other Salmonella species.