Antibiotic Resistance Testing Research Articles

Seafood as a source of antibiotic resistant Enterococcus spp

Seafood is a crucial global food source, but its role as a reservoir for antibiotic-resistant pathogens is concerning. This study focuses on the prevalence of antibiotic resistance in retail seafood, using Enterococcus spp. as an indicator. Seven categories of raw seafood were collected from retail markets in Central Italy. Out of 422 samples, 288 tested positive for Enterococcus spp., resulting in a prevalence rate of 68.25% (CI95%: 63.66%-72.51%). The most common species were E. faecalis (48%) and E. faecium (17.4%). Enterococcus spp. was most frequently found in cephalopods, salmon, bivalves, and crustaceans than in sea bass and bream. The odds of Enterococcus spp. recovery were higher in frozen than in fresh samples, while there was no difference between farm-raised and wild-caught seafood. A subset of 102 isolates was selected for antibiotic resistance testing, showing the highest resistance rates to quinupristin/dalfopristin (52.94%) and tetracycline (27.45%). Over 70% of isolates were multidrug-resistant. Additionally, strains resistant to vancomycin and oxazolidinones, two last-resort antimicrobials, were detected. Vancomycin resistance was observed in E. casseliflavus and E. gallinarum, which are naturally resistant due to the vanC chromosomal cluster. The optrA gene, responsible for resistance to oxazolidinones and phenicols, was found in E. thailandicus and E. faecium, where it was located on to a transferable plasmid. In conclusion, this study confirms the widespread presence of Enterococcus spp. in retail seafood. The detection of multi-resistant isolates and resistance to last-resort antimicrobials highlights significant human health risks, stressing the importance of including Enterococcus spp. in seafood antibiotic resistance surveillance.

Clonal distribution and molecular characterization of Staphylococcus aureus isolated strains in Chania and Heraklion, Crete.

This study investigates the demographic distribution, antibiotic resistance profiles, and molecular characteristics of Staphylococcus aureus infections. The study was carried out in 141 patients, 60.4% male, in patients from Chania and Heraklion, Crete. The highest infection prevalence observed in the older adults (≥65 years) age group. The predominant infection types were skin lesions (39.72) and respiratory tract infection (22.7%). Antibiotic resistance testing revealed that 57.44% of strains were MRSA, with high resistance to Tetracycline, Ciprofloxacin, Kanamycine Erythromycin and Clindamycin. Molecular analysis showed 19.14% of strains were Pvl-positive, highlighting the presence of both MRSA and MSSA strains with Pvl genes. The study underscores the need for continuous surveillance and targeted infection control strategies to manage the spread of MRSA, particularly in vulnerable populations.

Hazard Characterization of Antibiotic-resistant Aeromonas spp. Isolated from Mussel and Oyster Shellstock Available for Retail Purchase in Canada

Surveillance and monitoring of foods for the presence of antimicrobial-resistant (AMR) bacteria are required to assess the risks these bacteria pose to human health. Frequently consumed raw or lightly cooked, live bivalve shellfish such as mussels and oysters can be a source of exposure to AMR bacteria. This study sought to determine the prevalence of third-generation cephalosporin (3GC) and carbapenem-resistant bacteria in live mussel and oyster shellstock available for retail purchase through the course of one calendar year. Just over half of the 180 samples (52%) tested positive for the presence of 3GC-resistant bacteria belonging to thirty distinct bacterial species. Speciation of the isolates was carried out using the Bruker MALDI Biotyper. Serratia spp., Aeromonas spp., and Rahnella spp. were the most frequently isolated groups of bacteria. Antibiotic resistance testing confirmed reduced susceptibility for 3GCs and/or carbapenems in 15 of the 29 Aeromonas isolates. Based on AMR patterns, and species identity, a subset of ten Aeromonas strains was chosen for further characterization by whole genome sequence analysis. Genomic analysis revealed the presence of multiple antibiotic resistance and virulence genes. A number of mobile genetic elements were also identified indicating the potential for horizontal gene transfer. Differences in gene detection by the bioinformatic tools and databases used (ResFinder. CARD RGI, PlasmidFinder, and MobSuite) are discussed. This study highlights the strengths and limitations of using genomics tools to perform hazard characterization of diverse foodborne bacterial species.

Assessment of the bioflocculant production and safety properties of Metabacillus hrfriensis sp. nov. based on phenotypic and whole-genome sequencing analysis

Bioflocculant is considered to have broad application prospect in multi fields for the nontoxic and biodegradation properties. Screening new bioflocculant-producing bacteria with high flocculating activity, stress resistance characteristics, and application security is a significant action in the development of the biofloc technique. A novel bioflocculant-producing species, Metabacillus hrfriensis CT-WN-B3, was isolated from alkali-tolerant strains distributing in Daqing, Heilongjiang Province, China. A strong activity flocculant was detected in the extracellular polymeric substance (EPS) of CT-WN-B3, which could form biofloc more effectively under alkali conditions, with a flocculating rate of more than 70 %. The principal component of the bioflocculant was identified as the polysaccharide of extracellular polymeric substance (EPS) because of its 75.183 ± 2.268 % flocculation contribution, which was very significantly higher than that of the protein and the lipid (p < 0.01). Basing on the whole-genome sequencing analysis of CT-WN-B3, none gene encodes a known virulence factor, but two genes correspond to antibiotic resistance. Antibiotic resistance tests showed CT-WN-B3 was resistant to clindamycin. In the assessment of the antimicrobial spectrum, no antibacterial active substance was detected in the supernatant of CT-WN-B3 culture. Totally, the results of the safety assessment had eliminated the doubts about the application risk of CT-WN-B3. These results indicated that CT-WN-B3 is an alkali-suitable flocculant-producing bacterium for application in multiple fields, under alkali conditions especially.

Isolation of Lactobacillus spp. from Healthy Infants' Feces and Study of their Antibiotic Susceptibility

This study aimed to isolate Lactobacillus spp. bacteria from the feces of healthy newborns and investigate their susceptibility to antibiotic resistance. 120 fecal samples were obtained from infants under 12 months of age and susceptibility was identified using biochemical tests and molecular identification methods. A total of 30 positive isolates, chosen randomly from the 90 positive samples, were selected to conduct a safety assessment. the isolates were analyzed for their hemolytic activity and susceptibility to antibiotics. Using 16S rRNA sequencing, a total of 30 positive isolates were determined to be lactobacillus spp. The results of the antibiotic resistance test indicated that the majority of the isolates showed susceptibility to tetracycline, chloramphenicol, gentamicin, clindamycin, and amoxicillin while demonstrating resistance to vancomycin, nalidixic acid, streptomycin, and amikacin. conclusion: Based on these specific traits, the isolates of Lactobacillus spp. demonstrated favorable qualities as probiotics.

Probiotic properties, whole-genome sequence analysis, and safety assessment of BreviBacillus borstelensis S8

In previous studies, BreviBacillus borstelensis S8 exhibited favorable enzyme production characteristics. In this study, the whole genome of Br borstelenensis S8 was sequenced to analyze its genomic sequence information and functions, investigating its genotype and potential probiotic properties. The whole genome sequence of S8 was determined to be 5,559,180 bp with an average GC content of 51.5%. A total of 5406 protein-coding genes were identified and annotated using NCBI Prokaryotic Genome Annotation. By comparing it with the complete genome sequences of Bacillus cereus strains, 1911 orthologous gene families were recognized. Genome analysis revealed the absence of active antibiotic resistance genes, virulence factor genes, and toxin-encoding genes. Safety assessments included hemolytic assays, antibiotic resistance tests, and evaluations of biogenic amine production. Functional gene analysis highlighted S8's metabolic pathways based on its genomic features. The presence of adhesion-related genes, stress response genes (e.g., acid and bile salts), antimicrobial gene clusters, and genes involved in vitamin and essential amino acid synthesis in the genome showcased the probiotic potential of S8. Simultaneously, analysis of hemolytic activity, biogenic amines production ability, acid and bile salt tolerance for the strain S8 also demonstrated its probiotic traits. The genomic exploration and probiotic activity of S8 revealed its potential as a probiotic, offering valuable genomic insights and a foundation for its safe utilization in the food industry.

Assessment of the Safety and Exopolysaccharide Synthesis Capabilities of Bacillus amyloliquefaciens D189 Based on Complete Genome and Phenotype Analysis.

Exopolysaccharides (EPS) are natural macromolecular carbohydrates with good functional activity and physiological activities, which can be utilized as an emulsifier, viscosity enhancer, stabilizer, gelling agent, and water retention agent in a wide range of food products. In this study, the whole genome of Bacillus amyloliquefaciens D189, an EPS-producing bacteria, was sequenced. The result showed that D189 contains a single, circular chromosome of 3,963,356bp with an average GC content of 45.74% and 3996 coding genes. The gene annotation results showed that D189 is a potentially safe strain and confirmed to be safe associated with hemolytic assay, and antibiotic resistance test. Meanwhile, D189 genome possessed 240 genes related to carbohydrate metabolism. More importantly, D189 could transport 9 sugars and contained a complete biosynthetic pathway for 8 nucleotide sugars. Based on the validation experiments, strain D189 could metabolize 8 sugars (glucose, sucrose, trehalose, fructose, cellobiose, maltose, mannitol, and N-acetyl-D-glucosamine) to produce EPS, with the highest yield of 1.212g/L when sucrose was the carbon source. Therefore, the whole genome sequencing preliminarily elucidated the physiological mechanism of EPS, providing several pathways for engineering D189 to further enhance the yield of EPS.

Pheno- and Genotypic Epidemiological Characterization of Vancomycin-Resistant Enterococcus faecium Isolates from Intensive Care Unit Patients in Central Türkiye.

Vancomycin-resistant Enterococcus faecium (VRE) has been detected in Türkiye. Only limited information is available on its dissemination in the central regions of the country. This study describes the first epidemiological characterization of VRE clinical isolates detected in patients in a hospital in the province of Aksaray. In this one-year study conducted between 2021 and 2022, stool samples from intensive care unit patients were screened for VRE using the phenotypic E-test method, and the antibiotic sensitivity test was analyzed by using the VITEK® 2 system. A molecular assay for confirmation of species level was carried out by 16S rRNA gene-based sequencing and testing for antibiotic resistance (vanA or vanB) and virulence factor-encoding genes (esp, asa1, and hyl). Further, genotypic characterization was determined by macro-restriction fragment pattern analysis (MRFPA) of genomic DNA digested with SmaI restriction enzyme. Of the total 350 Enterococcus positive patients from different hospital intensive care units, 22 (6.3%) were positive for VRE using the phenotypic E-test method. All isolates showed resistance to ampicillin, ciprofloxacin, vancomycin, and teicoplanin and positive amplification for the vanA gene. However, none of the isolates was positive for the vanB gene. The most prevalent virulence gene was esp. The results indicate that the isolates are persistent in the hospital environment and subsequently transmitted to hospitalized patients, thus representing challenges to an outbreak and infection control. These study results would also help formulate more effective strategies to reduce the transmission and propagation of VRE contamination in various hospital settings.

A Situation Analysis of the Capacity of Laboratories in Faith-Based Hospitals in Zambia to Conduct Surveillance of Antimicrobial Resistance: Opportunities to Improve Diagnostic Stewardship.

Antimicrobial resistance (AMR) is a public health problem exacerbated by the overuse and misuse of antibiotics and the inadequate capacity of laboratories to conduct AMR surveillance. This study assessed the capacity of laboratories in seven faith-based hospitals to conduct AMR testing and surveillance in Zambia. This multi-facility, cross-sectional exploratory study was conducted from February 2024 to April 2024. We collected and analysed data using the self-scoring Laboratory Assessment of Antibiotic Resistance Testing Capacity (LAARC) tool. This study found an average score of 39%, indicating a low capacity of laboratories to conduct AMR surveillance. The highest capacity score was 47%, while the lowest was 25%. Only one hospital had a full capacity (100%) to utilise a laboratory information system (LIS). Three hospitals had a satisfactory capacity to perform data management with scores of 83%, 85%, and 95%. Only one hospital had a full capacity (100%) to process specimens, and only one hospital had good safety requirements for a microbiology laboratory, with a score of 89%. This study demonstrates that all the assessed hospitals had a low capacity to conduct AMR surveillance, which could affect diagnostic stewardship. Therefore, there is an urgent need to strengthen the microbiology capacity of laboratories to enhance AMR surveillance in Zambia.

Genetic Characterization, Antibiotic Resistance, and Virulence Genes Profiling of Bacillus cereus Strains from Various Foods in Japan.

Bacillus cereus sensu stricto is a foodborne pathogen that causes food poisoning. Their spore and biofilm-forming abilities persist in various environments and foods. This study investigated the prevalence, virulence, antibiotic resistance, and genetic diversity of B. cereus s. s. strains isolated from various food samples. Of 179 samples, 22.34% were positive for B. cereus s. s., with significantly high detection rates in milk products and raw chicken meat. Forty strains were isolated from positive samples. Matrix-assisted laser desorption ionization/time of flight mass spectrometry analysis revealed nine distinct clusters and multi-locus sequence typing revealed 34 sequence types including 23 novel sequences, demonstrating high genetic diversity among the isolates. PCR analysis revealed that all the strains contained at least one toxin gene, but none contained the cytK gene. Antibiotic resistance tests revealed that all isolates were classified as multidrug-resistant, with high resistance levels, particularly to β-lactam antibiotics and vancomycin, but were susceptible to gentamicin. All isolates showed variations in biofilm formation. This study highlights the significant public health risk due to B. cereus s. s. and underscores the need for stringent monitoring and control measures in food production to manage antimicrobial resistance and ensure food safety.

A Comparative Evaluation of Bifilac Clausi Vs Enterogermina and Other Selected Brands for Probiosimilarity

Purpose: To compare the qualitative and quantitative parameters of various Bacillus clausii brands that are available in the Indian market with the International reference product, Enterogermina. Study Centre: JSS College of Pharmacy, Ooty Study Period: 06th Nov 2022 to 30th Dec 2022 Methods &amp; Materials: Various parameters like total spore count, number of strains isolated (based on their sensitivity/ resistance pattern to antibiotics), pH &amp; Transmittance, antibiotic resistance test, microbial purity, DNA sequencing and species identification were tested with various Bacillus Clausii brands that are available in Indian market and were compared with the International reference product, Enterogermina. Results: Only Bifilac Clausi (Bacillus clausii - TIL 19T, TIL 21C, TIL 28S, TIL 30R) a product of Tablets (India) Limited passed all the qualitative and quantitative parameters in terms of assay, same number of strains (4 strains), taxonomical similarity, pH and suspension clarity, as well as resistance/sensitivity pattern to commonly used antibiotics. Conclusion: Based on the results of the testing of various Bacillus clausii formulations, we conclude that only Bifilac Clausi (Bacillus clausii - TIL 19T, TIL 21C, TIL 28S, TIL 30R) showed a similarity to the International reference product, Enterogermina. Hence Bifilac Clausi was found to be probiosimilar to Enterogermina and is a viable alternative to Enterogermina to provide similar probiotic benefits. Keywords: [Probiosimilar, Bacillus clausii formulation, Indian market, Qualitative &amp; Quantitative parameters, 16S RNA sequence]

Prevalence And Pattern Sensitivity Multidrug Antibiotics Resistant Pseudomonas aeruginosa in the High Care Unit at Dr. Soetomo General Academic Hospital Period 2022-2023

The prevalence of Multidrug antibiotic-resistant Pseudomonas aeruginosa (MDRPA) has been increasing during the decade And has become attention in hospital patients. This retrospective descriptive descriptive aimed to determine the prevalence of MDRPA and its sensitivity patterns. Data were taken from results of bacterial culture and antibiotic resistance tests from various clinical specimens from patients at Dr. Soetomo General Academic Hospital throughout 2022-2023. The resistance test was carried out using a Vitek 2 compact instrument. MDRPA is defined as Pseudomonas aeruginosa that is not sensitive to three or more of the following classes of antibiotics: meropenem or imipenem, ciprofloxacin, gentamicin or amikacin, ceftazidime or cefepime, and piperacillin/ tazobactam. The prevalence of MDRPA was 57.0%. MDRPA isolates were also the most common origin from the burn unit and HCU A (high care unit A), mostly from pus specimens and sputum. Pseudomonas aeruginosa sensitivity was best with piperacillin/tazobactam (55.5%), meropenem (54.8%), amikacin (47.5%), gentamicin (46.5%), cefepime (46.3%), ceftazidime (45.0%), ciprofloxacin (44.7%) and aztreonam (43.2%). The sensitivity of MDRPA to antibiotics is much lower than that of Pseudomonas aeruginosa. This study showed high number of MDRPA specifically in Surabaya and the pattern sensitivity of Pseudomonas aeruginosa can become guidelines in choosing antibiotics treatment for patients.

Population structure and antibiotic resistance of swine extraintestinal pathogenic Escherichia coli from China

Extraintestinal Pathogenic Escherichia coli (ExPEC) pose a significant threat to human and animal health. However, the diversity and antibiotic resistance of animal ExPEC, and their connection to human infections, remain largely unexplored. The study performs large-scale genome sequencing and antibiotic resistance testing of 499 swine-derived ExPEC isolates from China. Results show swine ExPEC are phylogenetically diverse, with over 80% belonging to phylogroups B1 and A. Importantly, 15 swine ExPEC isolates exhibit genetic relatedness to human-origin E. coli strains. Additionally, 49 strains harbor toxins typical of enteric E. coli pathotypes, implying hybrid pathotypes. Notably, 97% of the total strains are multidrug resistant, including resistance to critical human drugs like third- and fourth-generation cephalosporins. Correspondingly, genomic analysis unveils prevalent antibiotic resistance genes (ARGs), often associated with co-transfer mechanisms. Furthermore, analysis of 20 complete genomes illuminates the transmission pathways of ARGs within swine ExPEC and to human pathogens. For example, the transmission of plasmids co-harboring fosA3, blaCTX-M-14, and mcr-1 genes between swine ExPEC and human-origin Salmonella enterica is observed. These findings underscore the importance of monitoring and controlling ExPEC infections in animals, as they can serve as a reservoir of ARGs with the potential to affect human health or even be the origin of pathogens infecting humans.

Antibiotic Resistance Patterns in Bacterial Conjunctivitis

Background: The conjunctivitis, known generally as pink eyes, is the inflammation of the inner eyelids, as well as the entire surface of the eye´s outermost part, which makes it get a reddish-pink look. The symptoms may involve pain, burning and itching, most often when an allergic cause is implicated. Method: The present work considered 306 scenarios of human blepharitis, cultured swabs were plated on MacConkey agar and Blood agar used streak technique and incubated at 37°C in a 24-hour experiment. Bacterial isolates were pointed based on their appearance, gram-staining, direct microscopy and biochemical tests comprising of catalase, oxidase, mannitol fermentation and hemolysis. Enterosystem 18 R system and the Vitek-2 compact system were used for the confirmation of bacterial species. Microplate method was used to test for biofilm formation of the bacterial isolates. Results: Antibiotic resistance test of isolates, however, reflected relatively high resistance among them, with Staphylococcus aureus, Pseudomonas aeruginosa, Streptococcus pneumoniae, Moraxella catarrhalis and Klebsiellapneumoniae all being 100% resistant to amoxicillin. Klebsiella pneumonia and E. coli isolates showed a 90% resistance to moxifloxacin, and to ciprofloxacin by Staphylococcus aureus isolates. Pseudomonas aeruginosa, Klebsiella pneumoniae, Proteus vulgaris, and Streptococcus pneumoniae exhibited significant biofilm production, whereas the other isolated species showed lower biofilm-forming tendencies.

Anti-fungal effects of lactic acid bacteria from pickles on the growth and sterigmatocystin production of Aspergillus versicolor

Sterigmatocystin (STC) is an emerging mycotoxin that poses a significant threat to the food security of cereal crops. To mitigate STC contamination in maize, this study employed selected lactic acid bacteria as biocontrol agents against Aspergillus versicolor, evaluating their biocontrol potential and analyzing the underlying mechanisms. Lactiplantibacillus plantarum HJ10, isolated from pickle, exhibited substantial in vitro antifungal activity and passed safety assessments, including antibiotic resistance and hemolysis tests. In vivo experiments demonstrated that L. plantarum HJ10 significantly reduced the contents of A. versicolor and STC in maize (both >84 %). The impact of heat, enzymes, alkali, and other treatments on the antifungal activity of cell-free supernatant (CFS) was investigated. Integrated ultra-high-performance liquid chromatography (UPLC) and gas chromatography–mass spectrometry (GC–MS) analysis revealed that lactic acid, acetic acid, and formic acid are the key substances responsible for the in vitro antifungal activity of L. plantarum HJ10. These metabolites induced mold apoptosis by disrupting cell wall structure, increasing cell membrane fluidity, reducing enzyme activities, and disrupting energy metabolism. However, in vivo antagonism by L. plantarum HJ10 primarily occurs through organic acid production and competition for growth space and nutrients. This study highlights the potential of L. plantarum HJ10 in reducing A. versicolor and STC contamination in maize.

Identification and antibiotic resistance patterns of Klebsiella sp. isolated from the feces of Bornean Orangutans (Pongo pygmaeus) at Taman Safari Indonesia, Bogor

Orangutans are the only great apes that still survive in the Southeast Asian Region. However, their population in the wild habitat continues to decline, with estimates indicating a 50% decreased over the last 60 years. There is limited microbiological data on the antibiotic resistance of Klebsiella sp. in the feces of Bornean Orangutan (Pongo pygmaeus). This study aimed to identify the presence of Klebsiella sp. and assess its resistance pattern to various antibiotics in the feces of Bornean Orangutans. The research involved isolation, identification, and antibiotic resistance testing. Results showed that three isolates (37.5%) were positive for Klebsiella sp. Sensitivity test revealed two distinct resistance patterns among Klebsiella sp. isolates from the feces of healthy P. pygmaeus in Taman Safari Indonesia, Bogor. These isolates exhibited resistance to β-lactam antibiotics but remained sensitive to aminoglycoside, tetracycline, and fluoroquinolone antibiotics.

Isolation, identification, antibiotic resistance profile and molecular analysis of Ornithobacterium rhinotracheal isolates from turkeys.

Ornithobacterium rhinotracheal (ORT) infects numerous birds, particularly chickens and turkeys. ORT is an emerging bacterial pathogen of global concern in the poultry industry. As ORT is rapidly spreading throughout commercial poultry, it requires intensive studies of its epidemiology, diagnostic procedures, molecular typing, virulence genes and antimicrobial resistance. The present study was conducted in isolation and identification of ORT from slaughtered turkeys. Cleft palate swabs of 200 were collected from slaughtered turkeys and cultured on blood agar. ORT was characterized using biochemical tests and PCR targeting the ORT 16S rRNA gene. Virulence genes of isolates were determined targeting adenylate kinase (adk), copA and virulence-associated protein D (vapD) genes. Additionally, diversity of ORT isolates was performed by enterobacterial repetitive intergenic consensus (ERIC) and RAPD PCR. Disk diffusion was used to determine the antibiotic sensitivity of the isolates. ORT was identified in 23 (11.5%) samples using both the biochemical tests and PCR. The result of detecting virulence genes showed that all the isolates (23: 100%) had the adk gene, whereas two (8.7%) isolates had the copA gene, and seven (30.43%) isolates had the vapD gene. Molecular typing of isolates revealed 21 different patterns by RAPD PCR assay using M13 primer and 20 distinct patterns by ERIC PCR test. Both ERIC and RAPD PCR were distinctive methods for investigating the genetic diversity of ORT isolates. The antibiotic resistance test showed that 18 (78.26%) isolates were resistant to gentamicin, amikacin, cefazolin, streptomycin and penicillin. All isolates (100%) were resistant to cloxacillin and fosfomycin. This study showed the prevalence of ORT in turkey and high resistance of this bacterium to many common veterinary antibiotics. Moreover, both ERIC and RAPD PCR are distinctive methods for investigating the genetic diversity of ORT isolates. These data may help monitor antibiotic resistance and typing of ORT in epidemiological studies and serve as the foundation for designing region-specific vaccines for future use.

Investigating lactic acid bacteria genus Lactococcus lactis properties: Antioxidant activity, antibiotic resistance, and antibacterial activity against multidrug-resistant bacteria Staphylococcus aureus

BackgroundLactic acid bacteria (LAB) are utilized as a starter culture in the manufacturing of fermented dairy items, as a preservative for various food products, and as a probiotic. In our country, some research has been carried out, even if LAB plays a principal role in food preservation and improves the texture and taste of fermented foods, that is why we tried to evaluate their probiotic effect. The objective of this research was to determine the antibacterial activity of Lactococcus lactis (L. lactis) against Staphylococcus aureus (S. aureus) ATCC 29213, investigate their antioxidant activity, and characterize their sensitivity against 18 antibiotics. MethodsA total of 23 LAB (L. lactis subsp. cremoris, L. lactis subsp. Lactis diacetylactis, L. lactis subsp. lactis) were isolated from cow's raw milk. The antibacterial activity was performed using two techniques, competition for nutrients and a technique utilizing components nature, using the disk diffusion method. The sensitivity of the studied LAB to different antibiotics was tested on Man rogosa sharp (MRS) agar using commercial antibiotic disks. All strains of LAB were examined for their antioxidant activity. The antioxidant activity of L. lactis was tested by 2,2-diphenyl-1 picrylhydrazyl (DPPH). ResultsThe results showed that the MRS medium was more adapted than Muller Hinton Agar (MHA) to investigate the antibacterial activity of L. lactis against S. aureus ATCC 29213. Also, L. lactis exhibited a notable degree of antibacterial activity against S. aureus ATCC 29213. L. Lactis subsp. Lactis displayed higher antibacterial activities, followed by L. lactis ssp. lactis biovar. diacetylactis, and lastly, L. lactis ssp. cremoris against S. aureus ATCC 29213. Lc 26 among all strains of L. lactis showed a high potential antibacterial activity reaching 40 ± 3 mm against S. aureus ATCC 29213. All strains of L. lactis showed a slightly moderate antioxidant activity (10.56 ± 1.28%-26.29 ± 0.05 %). The results of the antibiotic resistance test indicate that all strains of L. lactis were resistant to cefotaxime, sulfamethoxazole-trimethoprim, and streptomycin and were sensitive to Ampicillin, Amoxicillin, Penicillin G, Teicoplanin, Vancomycin, Gentamicin 500, Tetracycline, and Chloramphenicol. These test results indicate that this strain falls within the criteria of not posing any harmful effects on human health. The important antibacterial properties recorded for all L. Lactis strains were derived from the production of antibacterial active metabolites, such as protein, diacetyl, hydrogen peroxide, and lactic acid, together with the fight for nutrients. ConclusionThis study suggests that the strains of L. lactis could be added as an antibacterial agent against S. aureus ATCC 29213 and can provide an important nutritional property for their antioxidant potential.

Serodiversity, antibiotic resistance, and virulence genes of Vibrio parahaemolyticus in oysters collected in coastal areas of northwestern Mexico between 2012 and 2020

This study aimed to determine the prevalence of V. parahaemolyticus in oysters from the northwestern coast of Mexico and to identify the serotypes, virulence factors, and antibiotic resistance of the strains. Oyster samples were collected from 2012 to 2020 from the northwest coast of Mexico; biochemical and molecular methods were used to identify V. parahaemolyticus from oysters; antiserum reaction to determine V. parahaemolyticus serotypes, and PCR assays were performed to identify pathogenic (tdh and/or trh) or pandemic (toxRS/new, and/or orf8) strains and antibiotic resistance testing. A total of 441 oyster samples were collected and tested for V. parahaemolyticus. Forty-seven percent of oyster samples were positive for V. parahaemolyticus. Ten different O serogroups and 72 serovars were identified, predominantly serotype O1:KUT with 22.2% and OUT:KUT with 17.3%. Twenty new serotypes that had not been previously reported in our region were identified. We detected 4.3% of pathogenic clones but no pandemic strains. About 73.5% of strains were resistant to at least one antibiotic, mainly ampicillin and ciprofloxacin; 25% were multi-drug resistant. In conclusion, the pathogenic strains in oysters and antibiotic resistance are of public health concern, as the potential for outbreaks throughout northwestern Mexico is well established.

In Vitro Evaluation of Gastrointestinal Stability of Pediococcus pentosaceus Isolated from Fermented Maize and Pearl Millet for Possible Novel Chicken Probiotic Development

Research has identified certain bio-based products, such as probiotics, as alternatives to antibiotics for use in animal feed. They are capable of controlling, preventing or minimizing the colonization of the gastrointestinal tract by pathogenic bacteria. To isolate Pediococcus spp. and assess its technological properties for possible probiotic development, maize and pearl millet were used. The cereals were steeped and wet milled after 48 h of fermentation. The milled cereals were kneaded into dough for 24 h, after which a 10% slurry was prepared for tenfold serial dilution to enumerate the LAB by employing pour plate techniques using MRS Agar. Based on the cell morphology of the isolated bacteria, eight isolates (four from maize and four from millet) that were selected for identification using MALDI-TOF MS showed that five were Pediococcus pentosaceus (P. pentosaceus), one was Pediococcus acidilactici, and two did not match any organism. Subsequently, the six isolates were labeled as MZ1, MZ2, MZ3, MZ4 for the maize isolate and MLT5 and MLT7 for the millet isolate. The six Pediococcus spp. were assessed in vitro for acid and bile salt tolerance, gastric juice and intestinal fluid tolerance and antibiotic resistance and antimicrobial susceptibility tests were performed, and the survivability rate of the strains was calculated. With regard to the mean count, there was a reduction in log10 CFU/mL under the lower pH conditions and their duration of exposure with regard to time. Among the isolates, no differences were noted at the various periods of exposure (0 h, 1 h, 2 h and 3 h) at pH 4 (p &gt; 0.05). However, significant differences were noted at pH 3, 2 and 1 among the isolates (p &lt; 0.05). The percentage survival of MZ4 and MLT7 at pH 1 was higher compared to the other isolates at 0 h. Significant differences were observed among the isolated at pH 2, 3 and 4 across the various periods. The mean count of the isolates in gastric juice was similar at 0 and 1 h, but significant differences were noted at 2 and 3 h, where MLT7 was highest (p &lt; 0.05). A similar trend was observed for percentage survival. The mean count and the percentage survival of isolates under different concentrations of bile salt were similar. Significant differences were noted among isolates in both mean count and percentage survival when exposed to intestinal fluid (p &lt; 0.05). All of the isolates were highly tolerant to the antibiotics tested and possessed antibacterial properties against the selected pathogens. The LABs proved to be good probiotic materials, according to the results obtained. However, the Pediococcus strain MLT7 proved to be the LAB of choice; therefore, its molecular identity was verified using the 16S rRNA sequence and was labeled as Pediococcus pentosaceus GT001 after it was discovered to have 100% similarity with some strains of Pediococcus pentosaceus.