Antibiotic-resistant Foodborne Pathogens Research Articles

Therapeutic use of biologically produced sulfur nanoparticles from Allium fistulosum against antibiotic-resistant foodborne pathogens

Abstract. Saddiqua A, Ullah S, Khan MS, Rehman S, Abubakar AA, Safdar K, Ali S, Javaria S, Kanwal A, Batool SN, Bhatti F, Sucipto TH, Ansori ANM. 2024. Therapeutic use of biologically produced sulfur nanoparticles from Allium fistulosum against antibiotic-resistant foodborne pathogens. Biodiversitas 25: 2348-2354. Food spoilage is a significant issue since foodborne illnesses affect millionsworldwide. The main root cause of food spoilage is the presence of microbes, some of which show resistance to commercially available antibiotic drugs. Therefore, it is essential to search for fresh and effective antibacterial medications. Nanotechnology can give solutions to fight against foodborne pathogens. Sulfur nanoparticles show many beneficial and effective results as antimicrobial agents. The aim of this study was to evaluate the efficacy of biologically synthesized sulfur nanoparticles from Allium fistulosum to inhibit antibiotic-resistant foodborne pathogens. The green synthesis of sulfur nanoparticles was done by combining plant leaf extract with sodium sulfide. This study used the plant Allium fistulosum to make sulfur nanoparticles. The characterization of SNPs was done through a scanning electron microscope, UV spectrophotometer, fourier transform infrared spectrometer, and nanoparticle tracking analysis. Then, the antimicrobial properties of the bioengineered sulfur-based nanoparticles against foodborne pathogens were checked alone and in combination with market-available antibacterial agents. Aspergillus flavus and Salmonella typhi were among the foodborne pathogens against which SNPs' in-vitro antibacterial activity was tested. Sulfur nanoparticles from Allium fistulosum had 291 nm absorption spectra showing to be almost 100 nm in size and had a spherical shape. The strongest antibacterial efficacy against S. typhi was observed by SNPs (24 mm). Synergistic antibacterial action was seen when nanoparticles were combined with antibiotics of commercial importance. A noticeable antifungal effect against A. flavus was observed by combining SNPs with amphotericin B. The findings of in vitro studies prove that novely designed sulfur nanoparticle have profound impacts on microorganisms. It was also observed that the effect of antibiotics like ampicillin and amphotericin B was enhanced when coupled with nanoparticles.

ANTIBIOTIC RESISTANCE OF ESBL-PRODUCING E. COLI AND OTHER GRAM-NEGATIVE BACTERIA ISOLATED FROM STREET-VENDED FOODS IN BANGLADESH

The prevalence and impact of antibiotic-resistant pathogens transmitted through food, particularly street-vended foods, is becoming a major public health concern. Although a significant proportion of the urban population in developing countries consumes street-vended foods, the role of these foods in spreading antibiotic resistance has been rarely investigated. In this study, 50 bacterial isolates were obtained from 25 samples representing five categories of street-vended foods: Phuchka, Chatpati, Sausage, Bun, and Salad. The IMVIC test revealed a notably high occurrence of Escherichia coli (n=32) within the collected samples. Three representative isolates were selected for molecular identification using DNA sequencing of 16S rDNA. They were identified as Klebsiella oxytoca, Burkholderia fungorum, and Serratia nematodiphila. The antibiotic susceptibility of the identified isolates (n=35) was investigated using twelve antibiotics following the Kirby-Bauer disk diffusion method. Around 65.63% of the E. coli isolates (n=21) exhibited multidrug resistance. Double Disc Synergy Test (DDST) and Phenotypic Confirmatory Disk Diffusion Test (PCDDT) confirmed ESBL production of Eight multidrug-resistant E. coli isolates (38.09%). The multiple antibiotic resistance (MAR) index showed that 22 E. coli isolates had MAR above 0.2, with resistance mostly against oxacillin, ampicillin, and cefuroxime. The Klebsiella oxytoca isolate showed multidrug resistance viz., ampicillin, oxacillin, cefuroxime, and kanamycin. The Burkholderia fungorum isolate showed no distinct inhibition zone against ampicillin and chloramphenicol. Additionally, the Serratia nematodiphila isolate showed no distinct inhibition zone against three antibiotics, including ampicillin, oxacillin, and cefuroxime. These findings might contribute to the knowledge of emerging antibiotic-resistant foodborne pathogens and raise concerns about the safety of street-vended foods in Bangladesh.

Effects of antibiotic-induced resistance on the growth, survival ability and virulence of Salmonella enterica

Salmonella enterica is an important foodborne pathogen that constitutes a major health hazard. The emergence and aggravation of antibiotic-resistant Salmonella has drawn attention widely around the world. Conducting a risk assessment of antibiotic-resistant foodborne pathogens throughout the food chain is a pressing requirement for ensuring food safety. The growth, survival capability, and virulence of antibiotic-resistant Salmonella represent crucial biological characteristics that play an important role in microbial risk assessment. In this study, eight antibiotic-sensitive S. enterica strains were induced by Ampicillin (Amp) and Ciprofloxacin (CIP), respectively, and AMP-resistant and CIP-resistant mutants were obtained. The growth characteristics under different temperatures (25, 30, 35 °C), viability after exposure to heat (55, 57.5, 60 °C) and acid (HCl, pH = 3.0), the virulence potential (adhesion and invasion to Caco-2 cells, biofilm formation and motility) and the lethality in a model species (Galleria mellonella) were evaluated and compared for S. enterica strains before and after antibiotic exposure. The induction by AMP and CIP are likely to promote cross-antibiotic resistance to their antibiotic classes, β-lactams and quinolones, as well as some compound antibiotics. It was observed that generally the antibiotic-induction-resistant strains showed decreased growth ability and lower heat resistance, although the differences were not significant at all the conditions tested. The AMP-resistant strains were significantly less acid resistance than the sensitive and the CIP-resistant ones, while exhibiting increased biofilm formation ability. In general, the antibiotic-induced resistance did not significantly affect the motility, adherence, or invasion ability of Caco-2 cells. However, CIP-resistant strains displayed lower lethality in G. mellonella infection, whereas AMP-resistant strains did not, and even two strains improved lethality. The study of the biological characteristics of antibiotic-resistant S. enterica is essential in better understanding the microbial risks to both the food chain and human health, thereby facilitating a more accurate risk assessment.

Biocontrol of Salmonella Typhimurium in milk, lettuce, raw pork meat and ready-to-eat steamed-chicken breast by using a novel bacteriophage with broad host range

Salmonella spp., one of the most frequently reported bacteria, causes foodborne illness and economic losses. Due to the threat of increasing antibiotic resistant foodborne pathogens, application of bacteriophages as novel antibacterial agents in food matrices has become an emerging strategy. In this study, a novel Salmonella phage PS3-1 with high lytic activity against Salmonella Typhimurium was identified from previously isolated phages. PS3-1 belonged to the class Caudoviricetes with a broad host range, and had relatively short latent period (15 min), large burst size (92 PFU/cell), high pH stability (pH 3.0–11.0) and thermal tolerance (4–60 °C). Genome sequencing analysis showed that PS3-1 genome consisted of 107,110 bp DNA, without antibiotic resistance and virulence related genes. The results of growth curve and time-kill assay showed that PS3-1 not only inhibited the growth of S. Typhimurium, but also effectively decreased the viable cell counts (0.30–4.72 log) after 24-h incubation at 7, 25 and 37 °C (P < 0.05). Moreover, >1.28 log of established biofilm cells were effectively removed after 24-h treatment with PS3-1. Besides, PS3-1 significantly reduced the viability of S. Typhimurium in milk, lettuce, raw pork meat and ready-to-eat steamed-chicken breast at different temperatures (P < 0.05). These results demonstrated that PS3-1 may be an excellent antibacterial agent for controlling S. Typhimurium in food industry.

Characterization of lactic acid bacteria isolated from street pickles of Dhaka, Bangladesh

Traditionally fermented pickles are a popular street food in Bangladesh famous for their unique flavors and health benefits. Pickles are often prepared by fermentation using lactic acid bacteria (LAB) that can act as probiotics. The study was aimed to isolate and characterize lactic acid bacteria from pickle samples collected from streets of Dhaka city, as well as assess the microbial quality of pickles for food safety.A total of 30 pickle samples of different kinds were collected from streets of Dhaka city. Isolation and identification were conducted using conventional cultural and biochemical tests, followed by molecular confirmation of identity. Antibiotic susceptibility of isolates was investigated against 7 antibiotics of different groups. Antimicrobial activity of LAB isolates was analyzed by well-diffusion assay and phenotypic enterocin activity assay. Physiological characterizations of LAB were performed to determine their tolerance to temperature, salt, pH, bile, carbohydrate fermentation pattern, proteolytic activity and biofilm formation.Fifty isolates were obtained from pickle samples, of which 18% was identified as LAB, including Enterococcus faecalis (6) and Enterococcus faecium (3). The rest included S. aureus (18), E. coli (11), Klebsiella spp. (5), Salmonella (3), Shigella (3) and Pseudomonas aeruginosa (1). Antibiotic resistance pattern revealed higher occurrence of resistance against azithromycin among the non-LAB isolates, but none of the LAB isolates were found to resist any of the antibiotics used. Antimicrobial activity of LAB isolates was not observed against the foodborne isolates. All LAB isolates fermented a wide range of carbohydrates and showed adequate tolerance to salt, pH, temperature and bile. Out of 9 isolates, 5 displayed proteolytic activity, and 6 were found as strong biofilm producer.These results suggest that although the LAB isolates from street pickles collected from Dhaka does not have antimicrobial activities, they still have potential to be used as probiotics. It also shows high occurrence of antibiotic resistant foodborne pathogens in pickles, indicating that consumption of such street food can be serious health hazard.

Occurrence and Multidrug Resistance in Strains of Listeria monocytogenes Recovered from the Anaerobic Co-Digestion Sludge Contained in a Single Stage Steel Biodigester: Implications for Antimicrobial Stewardship.

L. monocytogenes is a zoonotic foodborne pathogen with inherent adaptability to tolerate environmental and physiological stresses, thereby causing severe disease outbreaks. Antibiotic resistant foodborne pathogens are a challenge to the food industry. A total of 18 samples were pooled from a bio-digester co-digesting swine manure/pinewood sawdust, and evaluated for the occurrence of bacterium plus total viable counts using the spread plate method. The recovered bacterial isolates were presumptively identified by growth on selective medium and confirmed by biochemical characterisation, leading to the isolation of 43 L. monocytogenes. The isolates were characterized based on their susceptibility to antibiotics via the Kirby-Bauer disc diffusion technique against a panel of 14 antibiotics. Equally, the multiple antibiotic resistance (MAR) index was calculated, and MAR phenotypes generated. The bacterial counts were between 102 and104 cfu/mL. Complete susceptibility (100%) was demonstrated to ampicillin, gentamicin and sulfamethoxazole, which are the drugs of choice in the treatment of listeriosis. In addition, intermediate sensitivity occurred at 25.58% to cefotaxime, and the highest resistance (51.16%) was exhibited against nalidixic acid. The MAR index ranged from 0 to 0.71. Overall, 41.86% of the Listeria isolates displayed multidrug resistance, with 18 different MAR phenotypes, demonstrating CIP, E, C, TET, AUG, S, CTX, NA, AML, NI as the greatest MAR phenotype. It can be concluded that the isolates yielding MAR > 0.2 originated from the farm, where antibiotics had been in routine use. Therefore, strict monitoring of antibiotics use in the farm is crucial to mitigate further increase in antibiotic resistance amongst these bacterial isolates.

Carriage of Antibiotic Resistant Bacteria and Associated Factors Among Food Handlers in Tamale Metropolis, Ghana: Implications for Food Safety.

Bacteria pathogens constitute a significant proportion of diarrhoea-causing food contaminants. Transmission of antibiotic resistant foodborne pathogens to humans is a major threat to food safety, especially in developing countries where quality hygiene and sanitation facilities are lacking. Factors related to antibiotic use, sanitation and hand hygiene have been associated with the spread of infectious diseases as well as antibiotic resistant bacteria. Proper food handling ensures that food is not contaminated with potential pathogenic bacteria. This study assessed the carriage of antibiotic resistant bacteria and associated factors. A cross-sectional study was conducted among food handlers who sell ready to eat food in the Tamale metropolis of the Northern Region of Ghana. Food vending stations with huge customer base were randomly selected and the food handlers recruited using written informed consent. Structured questionnaires were used to collect participants sociodemographic details and information on sanitation, hand hygiene practice and antibiotic use. Sterile cotton swabs soaked in phosphate buffered saline was used to swab the palms of participating food handlers for bacteria isolation. All identified bacteria were tested for susceptibility to 12 antibiotics. In all, 406 food handlers participated in this study, the mean (SD) age was 26.5 (2.64) years. Bacteria isolated were predominantly Staphylococci 60 (14.8%) and Escherichia coli 54 (13.3%). All the isolates were resistant to at least one antibiotic tested. The isolates showed high resistance to broad-spectrum antibiotics such as ampicillin (40.0%-75.0%), tetracycline (40.0%-80.0%), amoxiclav (20.0%-80.0%) and chloramphenicol (7.7%-50.0%). Logistic regression model revealed that the carriage of antibiotic resistant bacteria by food handlers was significantly associated with age, educational level, years on the job, training in food preparation, hygiene practice, water source, type of toilet facility used and antibiotic use. Street food handlers could be potential sources of food-borne transmission of antibiotic resistant bacteria.

Antimicrobial Resistance Pattern of Escherichia coli O157:H7 Isolated from Cattle in West Java, Indonesia

Antimicrobials are commonly used in animal production to prevent disease and promote growth. This practice puts the public’s health at risk by causing commensals living in the intestinal tracts of food animals to inevitably develop antimicrobial resistance. Cattle are common hosts of E. coli O157:H7 but the bacteria do not infect them. Human hemorrhagic colitis (HC) and hemolytic-uremic syndrome (HUS) are known to be caused by E. coli O157:H7. Antibiotics are a common therapy and have been chosen to treat HC and HUS. However, it is now known that the E. coli strain is resistant to a wide range of antibiotics. The goal of this study was to determine the resistance pattern of E. coli O157:H7 isolated from cattle in Cianjur, Sukabumi, and Lembang, West Java, Indonesia. A total of 62 isolates of E. coli were tested for susceptibility to 15 types of antibiotics using agar diffusion techniques. Test results showed that E. coli O157:H7 is resistant to Sulphamethoxazole, Cephalotin, Ampicillin, Nalidixic Acid, Amoxicillin/Clavulanic Acid, Streptomycin, Tetracycline, Kanamycin, Trimethoprim, Gentamycin, Norfloxacin, Enrofloxacin, Ciprofloxacin, and Amoxicillin. There are differences in multi-drug resistance among the local isolates of E. coli O157:H7 tested, which were resistant to antibiotics of the 1-5 type (79.03%), 6-10 type (4.84%), and 11-15 type (4.84%). In order to control the occurrence of multidrug antibiotic resistance and stop the spread of antibiotic-resistant foodborne pathogens to humans, it is necessary to monitor the use of antibiotics in cattle on farms.

Emergence and spread of antibiotic-resistant foodborne pathogens from farm to table.

Antibiotics have been overused and misused for preventive and therapeutic purposes. Specifically, antibiotics are frequently used as growth promoters for improving productivity and performance of food-producing animals such as pigs, cattle, and poultry. The increasing use of antibiotics has been of great concern worldwide due to the emergence of antibiotic resistant bacteria. Food-producing animals are considered reservoirs for antibiotic resistance genes (ARGs) and residual antibiotics that transfer from the farm through the table. The accumulation of residual antibiotics can lead to additional antibiotic resistance in bacteria. Therefore, this review evaluates the risk of carriage and spread of antibiotic resistance through food chain and the potential impact of antibiotic use in food-producing animals on food safety. This review also includes in-depth discussion of promising antibiotic alternatives such as vaccines, immune modulators, phytochemicals, antimicrobial peptides, probiotics, and bacteriophages.

Biofabrication of ZnO nanoparticles using Acacia arabica leaf extract and their antibiofilm and antioxidant potential against foodborne pathogens.

Emergence of multidrug resistant pathogens is increasing globally at an alarming rate with a need to discover novel and effective methods to cope infections due to these pathogens. Green nanoparticles have gained attention to be used as efficient therapeutic agents because of their safety and reliability. In the present study, we prepared zinc oxide nanoparticles (ZnO NPs) from aqueous leaf extract of Acacia arabica. The nanoparticles produced were characterized through UV-Visible spectroscopy, scanning electron microscopy, and X-ray diffraction. In vitro antibacterial susceptibility testing against foodborne pathogens was done by agar well diffusion, growth kinetics and broth microdilution assays. Effect of ZnO NPs on biofilm formation (both qualitatively and quantitatively) and exopolysaccharide (EPS) production was also determined. Antioxidant potential of green synthesized nanoparticles was detected by DPPH radical scavenging assay. The cytotoxicity studies of nanoparticles were also performed against HeLa cell lines. The results revealed that diameter of zones of inhibition against foodborne pathogens was found to be 16–30 nm, whereas the values of MIC and MBC ranged between 31.25–62.5 μg/ml. Growth kinetics revealed nanoparticles bactericidal potential after 3 hours incubation at 2 × MIC for E. coli while for S. aureus and S. enterica reached after 2 hours of incubation at 2 × MIC, 4 × MIC, and 8 × MIC. 32.5–71.0% inhibition was observed for biofilm formation. Almost 50.6–65.1% (wet weight) and 44.6–57.8% (dry weight) of EPS production was decreased after treatment with sub-inhibitory concentrations of nanoparticles. Radical scavenging potential of nanoparticles increased in a dose dependent manner and value ranged from 19.25 to 73.15%. Whereas cytotoxicity studies revealed non-toxic nature of nanoparticles at the concentrations tested. The present study suggests that green synthesized ZnO NPs can substitute chemical drugs against antibiotic resistant foodborne pathogens.

The potential role of probiotics to adhere with caco-2 cells and control the antibiotic-resistant foodborne pathogens adhesion in vitro

The potential role of probiotics to adhere with caco-2 cells and control the antibiotic-resistant foodborne pathogens adhesion in vitro

Lactic acid bacterial bacteriocins and their bioactive properties against food-associated antibiotic-resistant bacteria

PurposeIncidence of foodborne diseases and growing resistance of pathogens to classical antibiotics is a major concern in the food industry. Consequently, there is increasing demand for safe foods with fewer chemical additives but natural products which are not harmful to the consumers. Bacteriocins, produced by lactic acid bacteria (LAB), is of interest because they are active in a nanomolar range, do not have toxic effects, and are readily available in fermented food products.MethodsIn this research, LAB were isolated from fufu, gari, kunu, nono, and ogi using De Mann, Rogosa, and Sharpe agar. Cell-free supernatants were prepared from 18-24 h LAB culture grown on MRS broth. Effect of organic acid was eliminated by adjusting the pH of the supernatants to 7.0 with 1M NaOH while the effect of hydrogen peroxide was eliminated by treating with Catalase enzyme. The supernatant was then filter-sterilized using a membrane filtration unit with a 0.2-μm pore size millipore filter and subjected to agar well diffusion assay against foodborne antibiotic-resistant bacteria.ResultA total of 162 isolates were obtained from the food samples. The antimicrobial sensitivity test yielded positive results for 45 LAB isolates against Staphylococcus aureus ATCC 25923 while 52 LAB isolates inhibited Escherichia coli ATCC 25922. On confirmation of the bacteriocinogenic nature of the inhibitory substance, 4 of the LAB isolates displayed a remarkable degree of inhibition to Leuconostoc mesenteroides, Salmonella typhimurium, and Bacillus cereus. Agar well diffusion assay was also performed against antibiotic-resistant foodborne pathogens using the cell-free supernatant (CFS) obtained from Lactobacillus fermentum strain NBRC15885 (Limosilactobacillus fermentum), Lactobacillus fermentum strain CIP102980 (Limosilactobacillus fermentum), Lactobacillus plantarum strain JCM1149 (Lactiplantibacillus garii), and Lactobacillus natensis strain LP33 (Companilactobacillus nantensis). The foodborne pathogens exhibited a notable level of resistance to antibiotics, with B. cereus exhibiting a resistance profile of 40%, S. aureus (50%), K. pnuemoniae (70%), E. coli (60%), and S. typhi (40%). The (CFS) was able to inhibit the growth of B. cereus, Klebsiella pneumonia, S. typhimurium, S. aureus, and E. coli.ConclusionTherefore, it portends that the bacteriocins produced by the LAB isolated from these food products could act as probiotics for effective inhibition of the growth of antibiotic-resistant foodborne pathogens.

Addressing the antibiotic resistance and improving the food safety in food supply chain (farm-to-fork) in Southeast Asia

Antibiotics are the compounds widely used to treat bacterial infections in human and variety of agricultural sectors including livestock farming, plants and crops, and aquaculture. However, rampant and uncontrolled use of antibiotics results in the emergence of resistant bacterial strains. Such resistant strains on the food chain possibly increase the risk of antibiotic resistant foodborne pathogens. Antibiotic resistant bacteria can reach human either directly via the contact with the infected animal or indirectly via the food chain through the consumption of contaminated food. Prevalence of antibiotic resistant bacteria in Southeast Asia region threatens the global public health as this region is regarded as a hotspot of antibiotic resistant bacteria. The risk of development of antibiotic resistance can be reduced only with appropriate regulation and policies. However, the lack of appropriate surveillance systems in this region leads to the absence of reliable national data on the level of antibiotics. To counteract the risk of antibiotic resistance, the World Health Organization (WHO) has published the global action plan on antimicrobial resistance which has been adopted by several countries in Southeast Asia.

Studies on the Antibacterial Activity and Chemical Composition of Methanol Extract of Cochlospermum tinctorium Root

The aim of study was to evaluate the antibacterial activity of Cochlospermum tinctorium against ten (10) strains of antibiotic resistant food-borne pathogens Staphylococcus aureus and Listeria monocytogene. Ten (10) strains of antibiotic resistant food-borne pathogens Staphylococcus aureus and Listeria monocytogene procured from Microbiology Research Laboratory Usman Danfodiyo University Sokoto. The roots of Cochlospermum tinctorium were collected from the rock side in Dambu Gomo, Zuru Local Government Area of Kebbi State, Nigeria. The roots were washed, air-dried and milled to powder using mortal and pestle and sieved to obtained fine powder. Maceration was used for extraction using methanol as solvent. The antibacterial activity of the plant was determined on Mueller Hinton agar using agar well diffusion method. Minimum concentration (MIC) and minimum inhibitory concentration (MBC) of plant extract was also determined. Thin layer chromatography and column chromatography was employed for separation and fraction of different compounds in the plant extract. The fractions were screened for antibacterial activity and active fractions having high antibacterial activity were subjected Gas Chromatography Mass Spectoscopy (GC-MS) analysis. The result of methanol extraction yield 5.17% extracts. The methanol extract of Cochlospermum tinctorium was effective in inhibiting the isolates at high concentration of 10 mg/mL. The results thin layer chromatography revealed four spots with Rf values 0.02, 0.37, 0.44 and 0.80 respectively. The GC-MS analysis of the active methanol extract of Cochlospermum tinctorium root powder revealed the existence of major peaks 1-(+)-Ascorbic acid 2,6-dihexadecanoate (R.T: 13.666), Diethyl phthalate (R.T: 10.440), Undecyl acetate (R.T: 10.007), 3-tetradecanone (R.T: 9.793), 3-hexadecanone (R.T: 12.427). It therefore concluded that the root of Cochlospermum tinctorium has immense potential to be used in the area of pharmacology as it possess antimicrobial activity against the antibiotic resistant food-borne pathogens, thus could be exploited as alternative antimicrobial drugs.

ANTIMICROBIAL PHENOTYPES OF GEOGRAPHICALLY MATCHED Staphylococcus aureus ISOLATED FROM BUFFALO’S MILK AND CLINICAL HUMAN CASES IN EGYPT: POTENTIAL ZOONOTIC RISKS

Global emergence of antibiotic-resistant food-borne pathogens is a major public health problem. This study aimed to determine the potential zoonotic risk of Staphylococcus aureus in buffalo's milk in Egypt. A total of 102 raw buffalo’s milk samples and 51 human nasal swabs were collected at Kafrelsheikh city, Egypt. All samples were examined for occurrence of S. aureus. Detected isolates were characterised based on DNase activity, mecA gene acquisition, and antibiotic resistance patterns. S. aureus was detected in 33.3% of buffalo's milk samples and29.4% of human nasal swabs. Multiple drug-resistant S.aureus (MDRSA) represented 88.2% and 90% of buffalo and human S. aureus isolates, respectively. Buffalo and human S. aureus isolates showed highest resistance rate for erythromycin (100%), and lowest resistance rate for gentamicin (22.2%). Interestingly, there was no significant difference in resistance patterns between methicillin-resistant S. aureus (MRSA) and methicillin-sensitive S. aureus (MSSA) (P&lt;0.46 - 0.97). One-third of the detected S. aureus phenotypes (5/15, 33.3%) were identical between buffalo and human isolates. Moreover, there was no significant difference in antibiotic resistance patterns between buffalo and human isolates (P&lt;0.1 - 0.97).This study highlights the potential public health risk of MDRSA transmission via buffalo's milk.Key words: buffalo’s milk, S. aureus, DNase, mecA, antibiogram, zoonotic risk

Poultry Farm and Poultry Products as Sources of Multiple Antimicrobial-Resistant Salmonella and S. aureus

Background: Poultry production is a key interface for the spread of novel zoonotic and antibiotic-resistant foodborne pathogens. Salmonella spp. and S. aureus isolates from 2 poultry production were tested for resistance to clinical antibiotics. Methods: One hundred 100 anal swab samples were aseptically collected from 2 small scale poultry farms located within Agulu, during the period of February 2016 to May 2016. The swab sticks were carefully transferred into the buffered peptone water and incubated at 37°C for 24hours and pre-enriched in sterile nutrient broth at 37°C for 24hours. After which, the culture was streaked on selective media Salmonella-shigella Agar and Mannitol Salt Agar using a sterile wire loop and further incubated at 37°C for 24 hours. S. aureus and Salmonella isolates were identified using standard microbiological identification techniques. The isolates were evaluated for antibiotic susceptibility, and for the expression of extended spectrum β-lactamase as well as vancomycin sensitivity. Results: One hundred bacterial isolates (44 S. aureus and 56 Salmonella spp.) were bacteriologically obtained from the poultry samples. Resistance pattern of the isolates to antibiotics was in the order of ceftazidime>cefuroxime>cloxacillin>augmentin®>ceftriaxone>erythromycin>gentamicin>ofloxacin for S. aureus while the Salmonella spp. had augmentin®>cefuroxime~ofloxacin>gentamicin>ceftazidime>ceftriaxone. Only 5.3% (3/56) Salmonella spp. was ESBL producers while 27.3% S. aureus were Vancomycin resistant. Conclusion: Our findings demonstrated that the poultry farm and poultry products could be a source of multiple antimicrobial-resistant Salmonella and S. aureus and may constitute a public health concern considering the circulation and consumption of livestock and their products, especially chickens and eggs.

Antimicrobial properties of rosin acids-loaded nanoparticles against antibiotic-sensitive and antibiotic-resistant foodborne pathogens

Rosin acids (RA) from coniferous trees are used in folk medicine for healing various skin infections. Despite the antimicrobial potential of RA, their poor solubility in aqueous media may limit their use. In this work RA-loaded polyethylene glycol-poly(lactic-co-glycolic acid) nanoparticles (RA-NPs) with enhanced antimicrobial properties against foodborne bacterial pathogens were produced. RA-NPs were prepared by solvent displacement technique and characterized for relevant colloidal features by dynamic light scattering, laser Doppler anemometry and transmission electron microscopy. Association of RA to NPs occurred with high yields (86% w/w). RA and RA-NPs (∼130 nm) were strongly active against antibiotic-sensitive Gram + pathogens, i.e. Clostridium perfringens, Listeria monocytogenes and antibiotic-resistant Staphylococcus aureus. However, both failed in inhibiting the growth of Gram – pathogens (Campylobacter jejuni, Campylobacter coli, Escherichia coli and Salmonella enterica). Association to NPs enhanced the antimicrobial activity of RA. MIC, IC50, IC90, and MBC values of RA-NPs were ten-times lower than RA. RA-NPs did not change the intrinsic toxicity potential of RA. This is the first study on the enhancement of the antimicrobial activity of RA when associated to nanocarriers. This approach may be an effective strategy to produce aqueous-based RA solutions with enhanced antimicrobial activity against antibiotic-sensitive and antibiotic-resistant Gram + pathogens.

Interrelationship between tetracycline resistance determinants, phylogenetic group affiliation and carriage of class 1 integrons in commensal Escherichia coli isolates from cattle farms

BackgroundCarriage of antibiotic-resistant foodborne pathogens by food production animals is one of many contributors to treatment failure in health care settings, and it necessitates an integrated approach to investigate the carriage of resistant pathogens harboring integrons in food-producing animals.MethodsEscherichia coli isolates with reduced susceptibility to tetracycline antibiotics (n = 92) were tested for associations between carriage of class1 integrons, phylogenetic group affiliation and tetracycline resistance determinants using the MIC method, PFGE analysis, PCR and sequencing.ResultsPhylogroups B1 and A were the most common (58.7 and 19.6%, respectively), followed by groups D (20.7%) and B2 (1.1%). All isolates carried at least one of the tet genes examined. In addition, 88 (95.7%) of all tetracycline-resistant isolates carried tet(A) or tet(B), while 47 (51.1%) and 41 (44.6%) harbored only tet(A) or tet(B), respectively. Likewise, isolates harboring these genes had a higher chance (P < 0.05) of carrying class 1 integrons. Of the tested isolates, 38 (41.3%) carried the intI1 gene. Classical integrons with complete genes (sul1 and qacE∆1) at the 3′-CS were recognized in 27 isolates. PCR screening and subsequent sequencing demonstrated that 84.2% (32/38) of the intI1-positive isolates harbored resistance gene cassettes. Overall, seven gene cassettes were identified, either solely or combined with another gene cassette. The most common gene was aadA1 (10 isolates), followed by a combination of aadA1-dfrA1 (seven isolates), aadA1-dfrA12 (six isolates) and aadA1-aadA2-dfrA12 (three isolates). Genetic typing using PFGE showed minimum clonal relatedness with 28 different clusters and 12–25 discernible DNA fragments.ConclusionsThis study brings new insight into the relationships between the presence of integrons, phylogenetic group association and characteristics of tetracycline antibiotic resistance determinants in commensal E. coli strains.

Pathogenic Characteristics and Antibiotic Resistance of Bacterial Isolates from Farmstead Cheeses.

The objective of this study was to investigate the pathogenicity and antimicrobial resistance of foodborne pathogens isolated from farmstead cheeses. Twenty-seven isolates, including 18 Bacillus cereus, two Escherichia coli, and seven Staphylococcus aureus, were subjected to polymerase chain reaction (PCR) to detect virulence genes and toxin genes, and the antibiotic resistances of the isolates were determined. All E. coli isolates were determined by PCR to be non-pathogenic. Among the 18 B. cereus isolates, 17 isolates (94.4%) were diarrheal type, as indicated by the presence of nheA, entFM, hbIC, cytK and bceT genes, and one isolate (5.6%) was emetic type, based on the presence of the CER gene. Among the seven S. aureus isolates, three (42.9%) had the mecA gene, which is related to methicillin-resistance. Most B. cereus isolates (94.7%) showed antibiotic resistance to oxacillin and penicillin G, and some strains also showed resistance to ampicillin (26.3%), erythromycin (5.3%), tetracycline (10.5%), and vancomycin (5.3%). These results indicate that microbial food safety measures for farmstead cheese must be implemented in Korea because antibiotic resistant foodborne pathogens, with resistance even to vancomycin, harboring virulence genes were found to be present in the final products of farmstead cheese.

Assessment of synergistic combination potential of probiotic and bacteriophage against antibiotic-resistant Staphylococcus aureus exposed to simulated intestinal conditions

This study was designed to evaluate the combined effect of probiotic Lactobacillus rhamnosus and bacteriophage SA11 on the control of antibiotic-sensitive Staphylococcus aureus (ASSA) and antibiotic-resistant S. aureus (ARSA) under the simulated intestinal conditions. The survivability of ASSA and ARSA were determined in the simulated phosphate-buffered saline (PBS)-, trypticase soy broth (TSB)-, and milk-based gastric juices adjusted to pH 2.0, 3.0, and 5.0 at 37 °C for 30 min. The inhibitory effect of bacteriophage SA11 and probiotic on the growth of ASSA and ARSA was evaluated in the simulated intestinal juices at 37 °C for 20 h. The least reductions in the numbers of ASSA and ARSA were observed in the milk-based gastric juices at pH 2.0 (<1 log). No significant changes in the teichoic acid-mediated sliding motility were observed for ASSA and ARSA after 30-min exposure to the simulated gastric juices (pH 2.0, 3.0, and 5.0), responsible for the enhanced bacterial attachment to the epithelial cells. The bacteriophage SA11 was stable down to pH 5.0 and up to 0.06 % bile salts. The bacteriophage SA11 combined with probiotic effectively inhibited the growth of ASSA and ARSA in the simulated intestinal conditions, showing more than 4 log reduction. The relative expression levels of adhesion-related genes (clfA, eno, and fnbA) and efflux-related genes (mdeA, norB, and norC) were less decreased in ARSA than in ASSA after exposure to the simulated gastrointestinal conditions. These results might shed light on the application of bacteriophage to control the ingested antibiotic-resistant foodborne pathogens in the intestinal tract.