Multidrug-Resistant Salmonella Isolates from Swine in the Eastern Cape Province, South Africa

One Health: a holistic approach for food safety in livestock

The food safety of livestock is a critical issue between animals and humans due to their complex interactions. Pathogens have the potential to spread at every stage of the animal food handling process, including breeding, processing, packaging, storage, transportation, marketing and consumption. In addition, application of the antibiotic usage in domestic animals is a controversial issue because, while they can combat food-borne zoonotic pathogens and promote animal growth and productivity, they can also lead to the transmission of antibiotic-resistant microorganisms and antibiotic-resistant genes across species and habitats. Coevolution of microbiomes may occur in humans and animals as well which may alter the structure of the human microbiome through animal food consumption. One Health is a holistic approach to systematically understand the complex relationships among humans, animals and environments which may provide effective countermeasures to solve food safety problems aforementioned. This paper depicts the main pathogen spectrum of livestock and animal products, summarizes the flow of antibiotic-resistant bacteria and genes between humans and livestock along the food-chain production, and the correlation of their microbiome is reviewed as well to advocate for deeper interdisciplinary communication and collaboration among researchers in medicine, epidemiology, veterinary medicine and ecology to promote One Health approaches to address the global food safety challenges.

Selection of Multidrug-Resistant Enterobacteria in Weaned Pigs and Its Association With In-feed Subtherapeutic Combination of Colistin and Tylosin

In-feed antibiotics are administered to piglets to improve performance and production efficiency. However, the use of growth promoters in the swine industry can select for multidrug-resistant (MDR) bacteria. Here, we evaluate the resistance profile of enterobacteria isolated from fecal samples of weaned pigs (21-35 days) fed or not with antibiotics (colistin and tylosin) and investigated the piglets gut microbiota in both groups. Six hundred and eighteen bacterial cultures were isolated from the control group (CON; n = 384) and antibiotic-fed pigs (ATB; n = 234). All isolates were tested for resistance to 12 antibiotics belonging to six distinct antibiotic classes. Isolates were highly resistant to ampicillin (90%; n = 553), amoxicillin (85%; n = 525), and tetracycline (81%; n = 498). A significant increase (P < 0.05) in resistance to cephalexin, kanamycin, doxycycline, and colistin was observed for bacteria from the ATB group. Piglets allocated in the ATB and CON groups shared similar intestinal microbiota, as revealed by alpha- and beta-diversity analyses. Our findings demonstrate that colistin and tylosin contribute to select MDR enterobacteria in weaned piglets. The high frequency of antibiotic resistance among isolates from the CON group suggests that environmental sources (e.g., fecal contents, aerosols, soil, water, food) also represent a potential reservoir of multidrug-resistant enterobacteria in pig production systems.

One Health Perspective of Salmonella Serovars in South Africa Using Pooled Prevalence: Systematic Review and Meta-Analysis

Salmonella is a bacterium that is commonly associated with food-borne infections and is regarded as one of the most important pathogens in public health. Salmonella serovars, particularly Typhimurium and Enteritidis, which are widely distributed globally, mainly result in outbreaks commonly linked to the consumption of animal products. This study is a systematic review and meta-analysis of studies reporting the prevalence of Salmonella serovars from one health perspective that included human, environmental, and animal samples in South Africa. PubMed, ScienceDirect, African Journals Online, and Scopus databases were used to conduct extensive searches of articles which were ultimately included or excluded following the Systematic Reviews and Meta-Analysis (PRISMA) guidelines. According to the data obtained in this review, the overall pooled prevalence estimates (PPE) of Salmonella serovars detection were 79.6%, 61.6%, 56.5%, and 43.2% for human, environment, animal, and environment/animal samples in South Africa, respectively. The majority of the studies (50%) used the polymerase chain reaction (PCR) technique for the detection of Salmonella serovars, followed by culture methods (26.7%), while 20% used serotyping. The PPE for nontyphoidal Salmonellae (NTS) was 65.6% and 34.4% for Salmonella Typhimurium and Salmonella Enteritidis, respectively. Our data further shows that 3 serovars, namely, Salmonella Typhimurium, Salmonella Enteriditis, and Salmonella Hadar, have been isolated from animals, humans, and the environment in South Africa. Our results highlight the ongoing spread of Salmonella spp. especially on animals which might end up infecting humans via direct contact with infected animals or eating infected animal products. This calls for deliberate “One Health” epidemiological studies in order to document information on the transmission between humans, animals, and the environment. This will ultimately result in the formulation of a consolidated salmonellosis control policy by the environmental, human, and veterinary health sectors.

Occurrence, Antibiotic Susceptibility and Genes Encoding Antibacterial Resistance of Salmonella spp. and Escherichia coli From Milk and Meat Sold in Markets of Bushenyi District, Uganda

The bacteriological safety of food/food products and the menace of antimicrobial resistance amongst enteropathogenic bacteria raise therapeutic management concerns within the public health system. Recently consumers of food/food products purchased from the public market of Bushenyi District presents with Enterobacteriaceae infection-associated symptoms and clinical conditions. We determine the molecular characterization and antibiotic signatures of some enteric bacterial recovered from foods/food products in markets of Bushenyi District, Uganda. Standard molecular biology techniques (Polymerase chain reaction PCR) and microbiological procedures were applied. Meat (MT) and milk (MK) samples were collected from 4 communities/town markets (Kizinda, Ishaka, Bushenyi, kashenyi) between April and September 2020 and analyzed. Our result reveals high differential counts of Salmonella species (175.33 ± 59.71 Log 10 CFU/100 ml) and Escherichia coli (53.33 ± 26.03 Log 10 CFU/100 ml) within the 4 markets with the count of Salmonella species higher than that of E. coli in each sampled market. The PCR further confirmed the detected strains (22.72% of E. coli and 54.29% of Salmonella species) and diverse multiple antibiotic-resistant determinants {TEM: (12 (23.1%) blaTEM-2 gene, 3 (5.8%) blaTEM gene}, 5 (9.6%) blaSHV gene, 3 (5.8%) bla-CTX-M-2, 1 (1.9%) bla-CTX-M-9 }. Other resistance genes detected were {10 (21.7%) strA gene} and 8 (17.4%) aadA gene} indicating a potential antibiotic failure. The need for alternative medicine and therapeutic measure is suggestive. Astute and routine surveillance/monitoring of potential pathogens and food products in the public market remains a core for maintaining future consumer safety.

Prevalence of Antibiotic Resistance in Salmonella Serotypes Concurrently Isolated from the Environment, Animals, and Humans in South Africa: A Systematic Review and Meta-Analysis

One of the main global concerns is the usage and spread of antibiotic resistant Salmonella serovars. The animals, humans, and environmental components interact and contribute to the rapid emergence and spread of antimicrobial resistance, directly or indirectly. Therefore, this study aimed to determine antibiotic resistance (AR) profiles of Salmonella serotypes isolated from the environment, animals, and humans in South Africa by a systematic review and meta-analysis. The preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines were followed to search four databases for studies published from 1980 to 2021, that reported the antibiotic resistance profiles of Salmonella serotypes isolated in South Africa. The AR was screened from 2930 Salmonella serotypes which were isolated from 6842 samples. The Western Cape province had high pooled prevalence estimates (PPE) of Salmonella isolates with AR profiles followed by North West, Gauteng, and Eastern Cape with 94.3%, 75.4%, 59.4%, and 46.2%, respectively. The high PPE and heterogeneity were observed from environmental samples [69.6 (95% CI: 41.7−88.3), Q = 303.643, I² = 98.353, Q-P = 0.045], animals [41.9 (95% CI: 18.5–69.5), Q = 637.355, I² = 98.745, Q-P = 0.577], as well as animals/environment [95.9 (95% CI: 5.4−100), Q = 55.253, I² = 96.380, Q-P = 0.300]. The majority of the salmonella isolates were resistant to sulphonamides (92.0%), enrofloxacin and erythromycin (89.3%), oxytetracycline (77.4%), imipenem (72.6%), tetracycline (67.4%), as well as trimethoprim (52.2%), among the environment, animals, and humans. The level of multidrug-resistance recorded for Salmonella isolates was 28.5% in this review. This study has highlighted the occurrence of AR by Salmonella isolates from animals, humans, and environmental samples in South Africa and this calls for a consolidated “One Health” approach for antimicrobial resistance epidemiological research, as well as the formulation of necessary intervention measures to prevent further spread.

Presence of Tetracycline and Sulfonamide Resistance Genes in Salmonella spp.: Literature Review

Tetracyclines and sulfonamides are broad-spectrum antibacterial agents which have been used to treat bacterial infections for over half a century. The widespread use of tetracyclines and sulfonamides led to the emergence of resistance in a diverse group of bacteria. This resistance can be studied by searching for resistance genes present in the bacteria responsible for different resistance mechanisms. Salmonella is one of the leading bacteria causing foodborne diseases worldwide, and its resistance to tetracyclines and sulfonamides has been widely reported. The literature review searched the Virtual Health Library for articles with specific data in the studied samples: the resistance genes found, the primers used in PCR, and the thermocycler conditions. The results revealed that Salmonella presented high rates of resistance to tetracycline and sulfonamide, and the most frequent samples used to isolate Salmonella were poultry and pork. The tetracycline resistance genes most frequently detected from Salmonella spp. were tetA followed by tetB. The gene sul1 followed by sul2 were the most frequently sulfonamide resistance genes present in Salmonella. These genes are associated with plasmids, transposons, or both, and are often conjugative, highlighting the transference potential of these genes to other bacteria, environments, animals, and humans.

Drug resistance and susceptibility testing of Gram negative bacterial isolates from healthy cattle with different β - Lactam resistance Phenotypes from Shandong province China

The objective of this study was to evaluate the effectiveness of common antibiotics against different microorganisms in apparently healthy cattle in Shandong province and its suburb. A total of 220 nasal swab samples were collected and cultured for bacteriological evaluation. All the bacteria isolates after preliminary identification were subjected to antibiogram studies following disc diffusion method. It was found in the study that E. coli is the most commonly associated isolate (21%), followed by Klebsiella spp. (18%), Pseudomonas aeruginosa (13%), Salmonella spp. (15%), Shigella spp (12%), and Proteus spp (11%). While the antibiogram studies reveled that highest number of bacterial isolates showed resistance to Ampicillin (95%), followed by Augmentin (91%), Cefuroxime (85%) and Tetracycline (95%) of (Escherichia coli and Klebsiella spp). In the case of pseudomonas spp. and Salmonella the highest resistance was showed by Ampicillin (90%) followed by Amoxicillin + Clavulanic Acid (80%), Cefixime (90%), and Erythromycin (80%). In Shigella spp and Salmonella spp highest resistance was showed by Amoxicillin, Ceftazidime, Augmentin (60%), and Amoxicillin + Clavulanic Acid (50%). It is concluded that in vitro antibiogram studies of bacterial isolates revealed higher resistance for Ampicillin, Augmentin, Cefuroxime, Cefixime, Tetracycline, Erythromycin, and Amoxicillin + Clavulanic Acid. The high multiple Antibiotics resistance indexes (MARI) observed in all the isolates in this study ranging from 0.6 to 0.9. MARI value of >0.2 is suggests multiple antibiotic resistant bacteria and indicate presence of highly resistant bacteria.

Preventing and managing antimicrobial resistance in the African region: A scoping review protocol

INTRODUCTION

Antimicrobial resistance (AMR) constitutes a significant threat to global health and food security, typically associated with high morbidity and mortality rate. The high burden of infectious diseases coupled with the weak health systems in most countries of Africa magnifies the risk of increasing AMR and its consequences thereof. This scoping review will be aimed at mapping the evidence on interventions used to prevent and manage antimicrobial resistance in Africa, guided by the "One Health" concept.

METHODS

We will consider interventions targeting multiple sectors such as health care systems, the agricultural and veterinary sectors. The outcomes to be considered include reduction of AMR decreased morbidity and mortality due to infectious diseases, increased awareness for rational use of antimicrobials and reduced antibiotic consumption. We will include all types of studies regardless of study designs conducted within the context of the WHO African region. Studies will be excluded if they are not conducted in Africa and if they are literature reviews, only describing the concept of AMR without mentioning interventions. We will include studies identified through a comprehensive search of peer-reviewed and grey literature databases. In addition, we will search the reference lists of included studies and relevant reviews. Finally, we plan to do a citation search for included studies. Findings of this review will be narratively synthesized.

Characterisation of Salmonella enterica clones carrying mcr-1 plasmids in meat products and patients in Northern Thailand using long read sequencing

Salmonella spp. is an important foodborne pathogen associated with consumption of contaminated food, especially food of livestock origin. Antimicrobial resistance (AMR) in Salmonella has been reported globally and increasing AMR in food production is a major public health issue worldwide. The objective of this study was to describe the genetic relatedness among Salmonella enterica isolates, which displayed identical DNA fingerprint profiles. Ten S. enterica isolates were selected from meat and human cases with an identical rep-PCR profile of serovars Rissen (n = 4), Weltevreden (n = 4), and Stanley (n = 2). We used long-read whole genome sequencing (WGS) on the MinION sequencing platform to type isolates and investigate in silico the presence of specific AMR genes. Antimicrobial susceptibility testing was tested by disk diffusion and gradient diffusion method to corroborate the AMR phenotype. Multidrug resistance and resistance to more than one antimicrobial agent were observed in eight and nine isolates, respectively. Resistance to colistin with an accompanying mcr-1 gene was observed among the Salmonella isolates. The analysis of core genome and whole genome MLST revealed that the Salmonella from meat and human salmonellosis were genetically related. Hence, it could be concluded that meat is one of the important sources for Salmonella infection in human.

Antimicrobial Resistance Profiles of Salmonella Isolates on Chickens Processed and Retailed at Outlets of the Informal Market in Gauteng Province, South Africa

The study determined the antimicrobial resistance profiles of Salmonella on chickens processed and retailed at outlets of the informal markets in Gauteng province, South Africa. The study also investigated the relationship of antimicrobial resistant Salmonella to the source and type of samples and their serotypes. Carcass swabs, cloacal swabs and carcass drips were randomly collected from each of 151 slaughtered chickens from six townships. Isolation and identification were performed using standard and polymerase chain reaction (PCR) methods. The disc diffusion method was used to determine the resistance of Salmonella isolates to 16 antimicrobial agents and PCR to determine their serovars. Ninety-eight (64.9%) of the 151 chickens were contaminated with Salmonella of which 94.9% (93/98) were resistant serovars. The frequency of antimicrobial resistance of Salmonella isolates was high to erythromycin (94.9%) and spectinomycin (82.7%) but was low to ciprofloxacin (1.0%) and norfloxacin (1.0%) (p < 0.05). All 170 isolates of Salmonella tested exhibited resistance to one or more antimicrobial agents and the frequency varied significantly (p < 0.05) across the townships, the type of samples and the serovars. The prevalence of multidrug resistance (MDR) in Salmonella was 81.8% (139/170). Our findings pose zoonotic, food safety and therapeutic risks to workers and consumers of undercooked, contaminated chickens from these outlets.

Characterization of Multidrug Resistance Patterns of Emerging Salmonella enterica Serovar Rissen along the Food Chain in China

Salmonella spp. are recognized as important foodborne pathogens globally. Salmonella enterica serovar Rissen is one of the important Salmonella serovars linked with swine products in numerous countries and can transmit to humans by food chain contamination. Worldwide emerging S. Rissen is considered as one of the most common pathogens to cause human salmonellosis. The objective of this study was to determine the antimicrobial resistance properties and patterns of Salmonella Rissen isolates obtained from humans, animals, animal-derived food products, and the environment in China. Between 2016 and 2019, a total of 311 S. Rissen isolates from different provinces or province-level cities in China were included here. Bacterial isolates were characterized by serotyping and antimicrobial susceptibility testing. Minimum inhibitory concentration (MIC) values of 14 clinically relevant antimicrobials were obtained by broth microdilution method. S. Rissen isolates from humans were found dominant (67%; 208/311). S. Rissen isolates obtained from human patients were mostly found with diarrhea. Other S. Rissen isolates were acquired from food (22%; 69/311), animals (8%; 25/311), and the environment (3%; 9/311). Most of the isolates were resistant to tetracycline, trimethoprim-sulfamethoxazole, chloramphenicol, streptomycin, sulfisoxazole, and ampicillin. The S. Rissen isolates showed susceptibility against ceftriaxone, ceftiofur, gentamicin, nalidixic acid, ciprofloxacin, and azithromycin. In total, 92% of the S. Rissen isolates were multidrug-resistant and ASSuT (27%), ACT (25%), ACSSuT (22%), ACSSuTAmc (11%), and ACSSuTFox (7%) patterns were among the most prevalent antibiotic resistance patterns found in this study. The widespread dissemination of antimicrobial resistance could have emerged from misuse of antimicrobial agents in animal husbandry in China. These findings could be useful for rational antimicrobial usage against Salmonella Rissen infections.

Antimicrobial Resistance Phenotype of Staphylococcus aureus and Escherichia coli Isolates Obtained from Meat in the Formal and Informal Sectors in South Africa

BACKGROUND

Foodborne diseases (FBD) caused by resistant pathogens are a global public health problem. One main driver of the increasing FBD incidence is the transfer of pathogenic organisms from animal guts to carcasses during processing and subsequent transfer from meat products to consumers.

METHODS

In this study, meat samples from abattoirs in the formal meat sector (FMS) (n = 140) and slaughter points in the informal meat sector (IMS) (n = 104) were collected for microbial detection and phenotypic AMR determination using polymerase chain reaction.

RESULTS

The antibiogram of Staphylococcus aureus isolates revealed that resistance to clindamycin (74.3%) and ampicillin (59.5%) was highest in the FMS, while resistance to penicillin (83.8%) and tetracycline (82.1%) was highest in the IMS. Escherichia coli isolates show significant resistance to chloramphenicol (90.7%) and tetracycline (82.3%) in the FMS. Likewise, resistance to tetracycline (92.3%) and sulfamethoxazole/trimethoprim (87.5%) was highest in the IMS. The multiple antibiotic resistance index (MARI) for S. aureus and E. coli ranged from 0.3 to 0.8 and 0.2 to 0.5, respectively.

CONCLUSION

This study suggests high-level contamination of meat with resistant pathogens and highlights the public health consequences associated with consuming such unhygienic products.

Antibiogram Signatures of Some Enterobacteria Recovered from Irrigation Water and Agricultural Soil in two District Municipalities of South Africa

This study was undertaken to evaluate the antibiogram fingerprints of some Enterobacteria recovered from irrigation water and agricultural soil in two District Municipalities of the Eastern Cape Province, South Africa using standard culture-based and molecular methods. The prevalent resistance patterns in the isolates follow the order: Salmonella enterica serovar Typhimurium [tetracycline (92.3%), ampicillin (69.2%)]; Enterobacter cloacae [amoxicillin/clavulanic acid (77.6%), ampicillin (84.5%), cefuroxime (81.0%), nitrofurantoin (81%), and tetracycline (80.3%)]; Klebsiella pneumoniae [amoxicillin/clavulanic acid (80.6%), ampicillin (88.9%), and cefuroxime (61.1%)]; and Klebsiella oxytoca [chloramphenicol (52.4%), amoxicillin/clavulanic acid (61.9%), ampicillin (61.9%), and nitrofurantoin (61.9%)]. Antibiotic resistance genes detected include tetC (86%), sulII (86%), and bla_AmpC (29%) in Salmonella enterica serovar Typhimurium., tetA (23%), tetB (23%), tetC (12%), sulI (54%), sulII (54%), catII (71%), bla_AmpC (86%), bla_TEM (43%), and bla_PER (17%) in Enterobacter cloacae., tetA (20%), tetC (20%), tetD (10%), sulI (9%), sulII (18%), FOX (11%) and CIT (11%)-type plasmid-mediated AmpC, bla_TEM (11%), and bla_SHV (5%) in Klebsiella pneumoniae and bla_AmpC (18%) in Klebsiella oxytoca. Our findings document the occurrence of some antibiotic-resistant Enterobacteria in irrigation water and agricultural soil in Amathole and Chris Hani District Municipalities, Eastern Cape Province of South Africa, thus serving as a potential threat to food safety.

The incidence of antibiotic resistance within and beyond the agricultural ecosystem: A concern for public health

The agricultural ecosystem creates a platform for the development and dissemination of antimicrobial resistance, which is promoted by the indiscriminate use of antibiotics in the veterinary, agricultural, and medical sectors. This results in the selective pressure for the intrinsic and extrinsic development of the antimicrobial resistance phenomenon, especially within the aquaculture‐animal‐manure‐soil‐water‐plant nexus. The existence of antimicrobial resistance in the environment has been well documented in the literature. However, the possible transmission routes of antimicrobial agents, their resistance genes, and naturally selected antibiotic‐resistant bacteria within and between the various niches of the agricultural environment and humans remain poorly understood. This study, therefore, outlines an overview of the discovery and development of commonly used antibiotics; the timeline of resistance development; transmission routes of antimicrobial resistance in the agro‐ecosystem; detection methods of environmental antimicrobial resistance determinants; factors involved in the evolution and transmission of antibiotic resistance in the environment and the agro‐ecosystem; and possible ways to curtail the menace of antimicrobial resistance.

Prevalence and antimicrobial resistance of retail-meat-borne Salmonella in southern China during the years 2009-2016: The diversity of contamination and the resistance evolution of multidrug-resistant isolates

Salmonella, one of the most important foodborne pathogens, can be the cause of bacterial food-borne illness and is commonly associated with the consumption of retail meat. Multidrug-resistant Salmonella isolates with high adaptability, have been responsible for many foodborne disease outbreaks. Here we present an investigation on the contamination and the antimicrobial resistance of Salmonella in retail meat obtained from supermarkets and from open markets in Guangxi, China. From the years 2009 to 2016, a total of 604 Salmonella isolates were recovered from a total of 3340 meat samples including 797 beef, 911 pork, 942 chicken and 690 duck, representing 18.08% of the samples tested. Pork was the most contaminated meat. Salmonella was detected in 322 samples from supermarkets and the positive rate of 21.03% was higher than that of 15.70% in 284 samples from open markets (P<0.05). The prevalence of Salmonella in retail meat in the summer and fall months: June (2015, 40.63%), October (2012, 34.6%; 2016, 43.75%) was higher than in other seasons of the year. One hundred and twenty-seven serotypes were identified among the 604 Salmonella enterica isolates, and S. Derby (28.48%), S. Agona (9.77%), S. London (4.97%) and S. Enteritidis (4.47%) were the most common serotypes. Tests of susceptibility to 21 antimicrobial agents showed that 87.58% of the isolates were resistant to at least one antimicrobial, and 57.79% exhibited multidrug resistance (MDR), as they were resistant to at least three antimicrobials. The presence of most of the antimicrobial-resistant genes tested was consistent with the resistant phenotypes found. Among all the antimicrobial resistant genes (ARGs) examined in this study, bla_TEM-1, aadA1, cmlA, tetA, sul1 and sul2 were the most prevalent resistant genes in the multidrug resistant isolates. Our findings show that there was a trend that the Salmonella contamination in retail meat had increased and isolates showed an MDR phenotype and that the MDR had become more and more serious. Twenty-one isolates of S. Agona were randomly analyzed by using the enterobacterial repetitive intergenic consensus sequence PCR (ERIC-PCR) and six different types were found, indicating the existence of cross-contamination in the food market. The results indicate that the hazard analysis of the critical control points (HACCP) system for the whole food chain of retail meat should be further analyzed and improved.

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.

Molecular Detection Of Multidrug-Resistant Salmonella Isolated From Livestock Production Systems In South Africa

BACKGROUND

Antibiotic-resistant bacterial pathogens associated with livestock remain a major concern worldwide as they get transmitted from animals to humans and cause foodborne and zoonotic diseases.

METHODS

Antimicrobial resistance in livestock-associated Salmonella spp in South Africa was investigated using molecular DNA methods. Three hundred and sixty-one environmental faecal samples were randomly collected from avian (chicken and ducks), cows, pigs, goats, and sheep. Salmonella spp. were isolated on selective media and were confirmed using the polymerase chain reaction. Antimicrobial susceptibility testing against ampicillin, chloramphenicol, ciprofloxacin, ceftriaxone, azithromycin, tetracycline, amoxicillin-clavulanate and trimethoprim-sulfamethoxazole was determined using the Kirby-Bauer disk diffusion method. Isolates were screened for the presence of blaTEM-1, blaCMY-2, tetA, tetC, sul2 and dfrA7 resistance genes by PCR.

RESULTS

Most of the isolates were resistant to ampicillin (64%), tetracycline (63%), amoxicillin-clavulanate (49%), trimethoprim-sulfamethoxazole (38%), and ceftriaxone (20%). Eight percent of the tested isolates were ciprofloxacin-resistant Salmonella spp. Multidrug resistance was observed with the mean multiple antibiotic resistance (MAR) index of 0.31. The study demonstrated that 43% of the isolates were multiple drug resistant. The prevalence rates of resistance genes were 44% for blaTEM-1 , 35% for blaCMY-2 , 21% for sul2, 18% for tetC, 14% for dfrA7 and 8% for tetA.

CONCLUSION

Resistance to ceftriaxone, detection of blaCMY-2 gene and the high level of intermediate susceptibility (33%) against ciprofloxacin suggested that livestock carry problematic Salmonella spp. This study used the global one-health initiative to report the potential public health risks of livestock-associated pathogens and highlights the importance of monitoring the trends of antimicrobial resistance for sustainability of antibiotics.

Antibiotic use in food animals worldwide, with a focus on Africa: Pluses and minuses

Antibiotics are frequently used in food animal production in developing countries to promote the well-being and growth of animals. This practice provides some economic benefits to producers and consumers at large. Nevertheless, this practice is also associated with a number of concerns. A major concern has been that repeatedly exposing these animals to small doses of antibiotics contributes significantly to antimicrobial resistance, since a good fraction of the antibiotics used are the same or surrogates of antibiotics used in human therapeutic practices. Studies over decades have shown an explicit relationship between antimicrobial use and antimicrobial resistance in veterinary science. Many antibiotics can be purchased over the counter in African countries, and antibiotic resistance is an important issue to address in this region. This review examines some of the risks and benefits associated with antibiotic use in food animals. We conclude that the use of antibiotics in food animal production constitutes a major contributing factor to the current antimicrobial resistance crisis and that antibiotics should only be used for the treatment of sick animals based on prior diagnosis of disease.

Antimicrobial Resistance and Genetic Diversity of Salmonella Serotypes Recovered from Edible Pork Offal from Korea

Although edible offal can be easily contaminated with foodborne bacteria and regarded as important transfers of antimicrobial resistance to humans, the characterization of bacteria from edible offal have not been researched sufficiently. This study is the first to focus on the molecular characterization of Salmonella isolated from edible pork offal. From a total of 52 Salmonella isolates from edible pork offal, 44 (80.7%) were resistant to at least one antimicrobial agent and 24 (46.2%) exhibited multidrug resistance (MDR). All MDR Salmonella were also resistant to β-lactams and 12 (50.0%) of the isolates were positive for bla_TEM-1. Eleven (68.8%) of the 16 gentamicin-resistant isolates harbored the ant(2'')-I gene. Among 18 tetracycline-resistant isolates, tetA and tetB genes were found in 9 (50.0%) and 3 (16.7%) isolates, respectively. The sul1 gene was identified in 9 (81.8%) of 11 trimethoprim/sulfamethoxazole-resistant isolates, and the cmlA gene was identified in only 2 (18.1%) among 11 chloramphenicol-resistant isolates. Eighteen (75.0%) of the 24 MDR Salmonella were identified as containing class 1 integrons, within which dfrA12-aadA2 (55.6%) was the most prevalent resistance gene cassettes. Twenty-one (87.5%) of the MDR isolates were also found to have the plasmid replicons. Replicon B/O (41.7%) was the most prevalent replicon types. These results suggest that edible pork offal can become a reservoir that not only harbors MDR Salmonella, but also contributes to their dissemination through cross-contamination processes.

Inhibitory effects of Azadirachta indica secondary metabolites formulated cosmetics on some infectious pathogens and oxidative stress radicals

BACKGROUND

Infectious diseases, particularly those due to multi-drug resistant bacterial strains are almost impossible to cure globally. In this study we investigated the inhibitory effects of Azadirachta indica A. Juss secondary metabolites (AISM) formulated soap and cream for management of infectious and oxidative stress-related diseases (OSD).

METHODS

The antibacterial, radical scavenging and cytotoxic effects of the neem cosmetics were examined by serial dilution, spectrophotometric and hemolytic techniques respectively, while the AISM in the essential oils (EOs) were elucidated by Gas chromatography-mass spectrometry (GC-MS) and retention index.

RESULTS

The neem cosmetics without AISM exhibited bacteriostatic effects against five reference bacterial strains (Staphylococcus aureus, Listeria ivanovii, Enterobacter cloacae, Mycobacterium smegmatis, and Streptococcus uberis) and two confirmed multi-drug resistant bacterial strains (Vibrio paraheamolyticues, Escherichia coli 180) at 0.80 mg/mL. Conversely, at less than 0.50 mg/mL the neem soap produced with AISM demonstrated bactericidal effects against most of these test pathogens linked to infectious diseases. The neem soap containing AISMs displayed noteworthy effects in scavenging radicals associated with OSD at < 1.76 mg/mL. The cosmetics were not toxic to human red blood cells below 0.70 mg/ mL. To our known, the AISM predominantly caryophyllene (30.02%), phytol (14.12%), elemene (13.40%) and linoleic acid (10.5%) exceptional inhibitory effects in neem cosmetics are reported here for the first time.

CONCLUSION

The study indicates that apart from traditional uses of A. indica, the EO contained potent bioactive AISM and feasible as an antimicrobial agent, an alternative to synthetic antioxidant, likewise considered novel in the pharmaceutical, cosmetics industries and as food preservatives.

Core genome sequence analysis to characterize Salmonella enterica serovar Rissen ST469 from a swine production chain

Salmonella enterica subsp. enterica serotype Rissen is the predominant serotype found in Thai pork production and can be transmitted to humans through contamination of the food chain. This study was conducted to investigate the genetic relationships between serovar Rissen isolates from all levels of the pork production chain and evaluate the ability of the in silico antimicrobial resistance (AMR) genotypes to predict the phenotype of serovar Rissen. A total of 38 serovar Rissen isolates were tested against eight antibiotic agents by a disk diffusion method and the whole genomes of all isolates were sequenced to detect AMR genetic elements using the ResFinder database.A total of 86.84% of the isolates were resistant to tetracycline, followed by ampicillin (78.96%) and sulfonamide-trimethoprim (71.05%). Resistance to more than one antimicrobial agent was observed in 78.95% of the isolates, with the most common pattern showing resistance to ampicillin, chloramphenicol, streptomycin, sulfonamide-trimethoprim, and tetracycline. The results of genotypic AMR indicated that 89.47% of the isolates carried tet(A), 84.22% carried bla_TEM-1B, 78.95% carried sul3, and 78.95% carried dfrA12. The genotypic prediction of phenotypic resistance resulted in a mean sensitivity of 97.45% and specificity of 75.48%. Analysis by core genome multilocus sequence typing (cgMLST) demonstrated that the Salmonella isolates from various sources and different locations shared many of the same core genome loci. This implies that serovar Rissen has infected every stage of the pork production process and that contamination can occur in every part of the production chain.

Molecular characterisation of antibiotic-resistant Salmonella enterica isolates recovered from meat in South Africa

Salmonella enterica is a leading cause of human gastroenteritis in both developed and developing countries, causing significant economic losses on humans and animals worldwide. There are several routes for contracting salmonellosis, but the consumption of contaminated foods is by far the most frequent cause of human infections. This study aimed to assess the prevalence and resistance determinants of S. enterica isolates obtained from meat. Swab samples from meat were cultured for the identification of Salmonella spp., and 239 presumptive S. enterica isolates were recovered, purified and kept in glycerol stocks. The S. enterica. confirmed by polymerase chain reaction (PCR) were further tested against 15 antimicrobials using the disc-diffusion method on Muller-Hinton agar and the genotypic antimicrobial resistance determinants by PCR. Resistance among tetracyclines, bêta-lactams, and 3rd generation cephalosporins was found to be most frequent with a noticeable rise in the number of multi-drug resistance ranging from two to seven antimicrobials. A total of 20 resistance determinants were assessed with their prevalence and distributions obtained as follows; [aminoglycosides: aadA (89%), aacC2 (100%), aphA1 (38%), aphA2 (0%) and strA (7%)], [β-lactams: (ampC 100%), blaTEM, (33%), blaZ (17%) and blaOXA (10%)], [Chloramphenicol: catI (9%), catII (7%), and cmIA1 (10%)] and [tetracyclines: tetA (57%), tetB (30%), tetC (11%), tetD (73%), tetK (20%) and tetM, (43%)], and [sulfonamides: sulI (82%), sulII (7%)]. The findings signify a high prevalence of multidrug-resistant (MDR) S. enterica isolates and resistance determinants indicating increased public health risks associated with the consumption of contaminated meat.

Systematic review in South Africa reveals antibiotic resistance genes shared between clinical and environmental settings

A systematic review was conducted to determine the distribution and prevalence of antibiotic-resistant bacteria (ARB), antimicrobial-resistant genes (ARGs), and antimicrobial-resistant gene determinants (ARGDs) in clinical, environmental, and farm settings and to identify key knowledge gaps in a bid to contain their spread. Fifty-three articles were included. The prevalence of a wide range of antimicrobial-resistant bacteria and their genes was reviewed. Based on the studies reviewed in this systematic review, mutation was found to be the main genetic element investigated. All settings shared 39 ARGs and ARGDs. Despite the fact that ARGs found in clinical settings are present in the environment, in reviewed articles only 12 were found to be shared between environmental and clinical settings; the inclusion of farm settings with these two settings increased this figure to 32. Data extracted from this review revealed farm settings to be one of the main contributors of antibiotic resistance in healthcare settings. ARB, ARGs, and ARGDs were found to be ubiquitous in all settings examined.

Aerobic Mesophilic, Coliform, Escherichia coli, and Staphylococcus aureus Counts of Raw Meat from the Formal and Informal Meat Sectors in South Africa

Foodborne disease (FBD) is a global public health concern, and foods from animal sources have been associated with outbreaks of food-related illness. In this study, animal carcasses from the two abattoirs (HT1 and HT2) in the formal meat sector (FMS) and slaughter points in the informal meat sector (INMS) were examined at two stages of slaughter (before washing and after washing) for aerobic colony counts (ACC) and total viable count (TCC), as well as Escherichia coli and Staphylococcus aureus count. At each stage, carcasses were sampled by swabbing at the neck, brisket, flank, and rump. ACC for beef, mutton, and pork carcasses at HT1 and HT2 before washing were between 2.5–5.8, 2.2–4.7, and 2.7–3.7 mean log CFU/cm², respectively, and TCC count before washing was highest on the neck of cattle (6.3 ± 2.4) and after washing was highest on the perineal of sheep (5.7 ± 6.9). In the INMS, TCC count was highest on the brisket (6.9 ± 3.2) and in the neck (5.5 ± 2.4). Higher ACC values of 6.2–6.7 mean log CFU/cm² were obtained in the INMS. The highest count for E. coli (4.2 mean log CFU/cm²) after washing was in the neck, while the highest count for S. aureus (4.0 mean log CFU/cm²) was in the flank. All bacteria count in the INMS exceeded acceptable limits, and washing did not significantly reduce microbial load in meat in the FMS and INMS. Bacteria count in the FMS and INMS exceeded acceptable standards. However, meat processed in the INMS poses a more significant risk of FBD to consumers.

Bioactive Constituents, Radical Scavenging, and Antibacterial Properties of the Leaves and Stem Essential Oils from Peperomia pellucida (L.) Kunth

Background:

Peperomia pellucida is an annual herbaceous ethnomedicinal plant used in the treatment of a variety of communicable and noncommunicable diseases in the Amazon region.

Objective:

The study aimed at profiling the bioactive constituents of the leaves and stem essential oils (LEO and SEO) of P. pellucida, their in vitro antibacterial and radical scavenging properties as probable lead constituents in the management of oxidative stress and infectious diseases. Materials and

Methods:

The EOs were obtained from the leaves and stem P. pellucida using modified Clevenger apparatus and characterized by a high-resolution gas chromatography-mass spectrometry, while the radicals scavenging and antibacterial effects on four oxidants and six reference bacteria strains were examined by spectrophotometric and agar diffusion techniques, respectively.

Results:

The EOs exhibited strong antibacterial activities against six bacteria (Escherichia coli [180], Enterobacter cloacae, Mycobacterium smegmatis, Listeria ivanovii, Staphylococcus aureus, Streptococcus uberis, and Vibrio paraheamolyticus) strains. The SEO antibacterial activities were not significantly different (P < 0.05) from the LEO against most of the test bacteria with minimum inhibitory concentration ranging between 0.15 and 0.20 mg/mL for both EOs. The two oils were bactericidal at 0.20 mg/mL against S. aureus while the minimum bactericidal concentration (0.15 mg/mL) of LEO against L. ivanovii was lower than of SEO (0.20 mg/mL) after 24 h. The LEO IC₅₀ value (1.67 mg/mL) revealed more radical scavenging activity than the SEO (2.83 mg/mL) and reference compounds against 2,2-diphenyl-1-picrylhydrazyl radical. The EOs also scavenged three other different radicals (2,2’-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt radical, lipid peroxyl radical, and nitric oxide radical) in concentration-dependent manner.

Conclusion:

Our results suggest that apart from the indigenous uses of the plant extracts, the EO contains strong bioactive compounds with antibacterial and radicals scavenging properties and may be good alternative candidates in the search for novel potent antibiotics in this present era of increasing multidrug-resistant bacterial strains as well as effective antioxidants agents.

SUMMARY

Established gas chromatography-mass spectrometry technique was applied to quantitatively and qualitatively analyze the volatile constituents in Peperomia pellucida essential oil (EO)

The Clinical and Laboratory Standards Institute (2014) guidelines were employed to evaluate the antibacterial effects of the EOs

Among the known prominent bioactive terpenoids, linalool 17.09%, limonene 14.25%, β-caryophyllene 12.52%, and linalyl acetate 10.15% were the main constituents of the EOs in this current study

The leaf and stem EOs were bactericidal at a concentration below 0.23 mg/mL against three multidrug-resistant bacteria and significantly scavenged known free radicals reported to be associated with contagious and oxidative stress-related disorders.

Abbreviations used: GC-MS: Gas chromatography-mass spectrometry, DPPH: 2,2-diphenyl-1-picrylhydrazyl, ABTS: 2,2-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt, DMSO: Dimethyl sulfoxide, LP^•: Lipid peroxide radical, NO^•: Nitric oxide radical, LEO: Leaf essential oil, SEO: Stem essential oil, RC: Reference compound, TBARS: Thiobarbituric acid

Bactericidal and antioxidant properties of essential oils from the fruits Dennettia tripetala G. Baker

Background

The antibacterial and antioxidant properties of the essential oils (EOs) of unripe and ripe fruits of Dennettia tripetala and their potential for the management of infectious and oxidative-stress diseases were investigated in-vitro in this study.

Method

Essential oil obtained from the fruit in Clevenger modified apparatus, was characterized by high resolution GC-MS, while antioxidant and antibacterial properties were tested by spectrophotometric and agar diffusion methods respectively.

Results

The EO demonstrated strong antibacterial properties when subjected to multi –drug resistant bacterial strains: Enterococcus faecium (ATCC19434), Escherichia coli (ATCC 700728), Staphylococcus aureus (NCINB 50080), Listeria ivanovii (ATCC 19119), Enterobacter cloacae (ATCC13047) and four previously confirmed multi resistant bacterial isolates from our laboratory stock culture. The unripe fruit oil (UFO) demonstrated greater activity than the ripe fruit oil (RFO) against most of the tested bacteria with minimum inhibition concentrations (MIC) ranging between 0.05–0.20 mg/mL while that of the ripe fruit oil (RFO) ranged from 0.10–0.20 mg/mL. The IC₅₀ for RFO (0.62 ± 0.12 mg/mL) showed that it has higher antioxidant strength than UFO and vitamin C (0.87 ± 0.23 and 3.39 ± 0.12 mg/mL) but a lower activity compared to β-carotene (0.32 ± 0.22 mg/mL) in scavenging 2, 2-diphenyl-1-picrylhydrazyl radicals (DPPH^•). The EOs also demonstrated strong ability in scavenging three other different radicals (ABTS, lipid peroxide and nitric oxide radicals) in concentration dependant -manner.

Conclusion

Findings from this study suggest that apart from the local uses of the plant extracts, the EO has strong bioactive compounds, noteworthy antibacterial, antiradical properties and may be good candidates in the search for lead constituents for the synthesis of novel potent antibiotics.