Virulence Gene Profiles Research Articles

Genetic diversity and virulence of Bacillus cereus group isolates from bloodstream infections.

Bacillus cereus catheter-related bloodstream infections (CRBSIs) are an increasing concern in Japanese hospitals. Although their clinical characteristics have been explored, the genetic relationships and virulence profiles of B. cereus isolates from CRBSIs remain understudied. Here, using advanced genomic techniques, we investigated the genetic diversity, phylogenetic relationships, and virulence profiles of B. cereus isolates from patients with bloodstream infections. We analyzed 28 B. cereus group strains isolated from blood samples at the University of Tokyo Hospital between 2005 and 2017 using whole-genome sequencing, core-genome single-nucleotide polymorphism (SNP) typing, and virulence gene profiling. Core-genome SNP analysis revealed significant genetic diversity among the isolates, suggesting multiple independent sources of infection. The isolates predominantly belonged to panC clades III and IV, with distinct virulence gene profiles. All panC clade III isolates contained hbl operon genes, whereas four isolates from clade IV harbored cereulide synthetase genes (cesABCD). One isolate possessed a capsule gene operon (capBCADE), a rare finding among clinical B. cereus strains. Biofilm formation ability was observed in 50% of catheter-related isolates, although this ability was not significantly different from that of the noncatheter-related isolates.IMPORTANCEThis study provides novel insights into the genetic diversity and virulence potential of B. cereus strains causing bloodstream infections in a Japanese hospital setting. These findings suggest diverse infection pathways and highlight the importance of continuous molecular epidemiological surveillance for effective infection control.

Antimicrobial Resistance, Virulence Gene Profiling, and Spa Typing of Staphylococcus aureus Isolated from Retail Chicken Meat in Alabama, USA

Antibiotic-resistant Staphylococcus aureus (S. aureus) in retail meat poses a public health threat requiring continuous surveillance. This study investigated the frequency of isolation, toxin genes, and antibiotic resistance profile of S. aureus recovered from retail poultry meat samples and presented results beneficial to public health interventions. Of 200 samples collected, 16% (32/200) tested positive for S. aureus, and these were recovered from thigh 37.5% (12/32), wing 34.4% (11/32), gizzard (15.6% (5/32), and liver 12.5% (4/32) samples. Findings of spa typing analysis revealed that 68.8% (22/32), 18.8% (6/32), 9.4% (3/32), and 3.0% (1/32) of the isolates belonged to the spa types t267, t160, t548, and t008, respectively. For antibiotic susceptibility testing, 12.5% (4/32) of the isolates were resistant to only penicillin, but one isolate (1/32; 3%) showed resistance to the antibiotics penicillin, erythromycin, ampicillin, and oxacillin. PCR analysis revealed that 9.4% (3/32) of the isolates carried the mecA gene associated with methicillin-resistant Staphylococcus aureus (MRSA) isolates. One MRSA isolate was identified as a t008 spa type, and harbored a 26,974 bp-sized plasmid, which was the source of its resistance to penicillin, ampicillin, erythromycin, and oxacillin. The staphylococcal enterotoxin (SE) genes seg, sei, sek, seb, selm, and seln were also identified among the isolates, and mostly the antimicrobial and enterotoxin genes were carried on plasmids of the isolates. This study raises awareness on the continuous circulation of pathogenic microbes like S. aureus in retail poultry meat.

Assessment of typing methods, virulence genes profile and antimicrobial susceptibility for clinical isolates of Proteus mirabilis

Proteus mirabilis (P. mirabilis) is one of the most important causative pathogens associated with complicated urinary tract infections with a 20% incidence. For epidemiological determinations, several phenotypic and molecular typing methods have been implicated. Sixty P. mirabilis isolated undergo antibiotic susceptibility test by standard Kirby Bauer method. They showed high resistance to nitrofurantoin and trimethoprim/sulfamethoxazole that appear mainly in 3rd age group. The 2nd age group comprised most of the resistant isolates to the tested antibiotics. A total of 73.33% of isolates were classified as multi drug resistance (MDR) and 78.3% of isolates were distributed in several antibiotypes with MAR index over 0.2. Twenty-one isolates were strong biofilm-producers and they were significantly related to MDR. Different virulence factors as protease, urease and hemolysin production are detected. Detection of several virulence genes by PCR; zapA and ureC were harbored by all isolates, followed by rsbA (95%), ureA and flaA (93%), hpmA (91.7%) and mrpA (73.3%). Determination of genetic diversity between isolates was performed by different methods (RAPD, ISSR, ERIC, BOX-AIR and REP-PCR) by using several parameters as typeability and discriminatory power indicating that ERIC-PCR was the best method followed by REP-PCR 1R. Rand’s & Wallace coefficients were used for calculating the congruence among typing methods. Conclusions: The results obtained from both conventional and molecular typing methods indicated that molecular methods are superior to conventional methods in the discrimination of isolates. ERIC-PCR and Rep-PCR provide high discrimination ability among P. mirabilis clinical isolates contributing to epidemiological studies.

Monitoring the Spread of Multidrug-Resistant Escherichia coli Throughout the Broiler Production Cycle.

The extensive use of antimicrobials in broiler production is changing the bird microbiota, fostering drug-resistant bacteria, and complicating therapeutic interventions, making the problem of multidrug resistance global. The monitoring of antimicrobial virulence and resistance genes are tools that have come to assist the breeding of these animals, directing possible treatments as already used in human medicine and collecting data to demonstrate possible dissemination of multidrug-resistant strains that may cause damage to industry and public health. This work aimed to monitor broiler farms in southern Brazil, isolating samples of E. coli and classifying them according to the profile of resistance to antimicrobials of interest to human and animal health. We also monitored the profile of virulence genes and conducted an epidemiological survey of possible risk factors that contribute to this selection of multidrug-resistant isolates. Monitoring was carried out on farms in the three southern states of the country, collecting samples of poultry litter, cloacal swabs, and beetles of the species Alphitobius diaperinus, isolating E. coli from each of these samples. These were evaluated by testing their susceptibility to antimicrobials of animal and human interest; detecting whether the samples were extended-spectrum β-lactamase enzyme (ESBL) producers; and when positive, selected for genotypic tests to identify resistant genes (CTX-M, TEM, and SHV) and virulence. Among the antimicrobials tested, enrofloxacin and ciprofloxacin demonstrated some of the highest frequencies of resistance in the isolated strains, with significant statistical results. The use of these antimicrobials increased the likelihood of resistance by over three times and was associated with a 1.5-fold higher probability of multidrug resistance. Of all isolates, 95% were multidrug-resistant, raising concerns for production and public health. Among 231 ESBL-positive samples, the CTX-M1 group predominated.

Salmonella enterica serovar Schwarzengrund: Distribution, Virulence, and Antimicrobial Resistance.

The global incidence of Salmonella enterica serovar Schwarzengrund has risen in recent years. This serotype has been isolated from poultry, retail meat, and other food products, leading to multiple outbreaks. Alongside the increase in infections, there are growing concerns about the increasing levels of antimicrobial resistance (AMR) among S. Schwarzengrund strains. This study aims to better understand the genetic factors possibly contributing to the rising prevalence of S. Schwarzengrund by analyzing the sequences of 2058 isolates from both human patients (N = 313) and food- and animal-associated sources, including chicken (N = 1145), turkey (N = 300), pork (N = 132), and other sources (N = 168). Data were obtained from GenBank and analyzed for AMR genes using AMRFinder. Additionally, putative virulence genes and plasmid transfer genes were assessed using the Virulence and AMR Plasmid Transfer Factor Database. AMR genes were found in 1269 (61.7%) of the isolates, with a total of 2478 AMR genes among the isolates, the most common being aph(3″)-Ib (N = 969, 47.1%), tet(A) (N = 190, 9.2%), and sul2 (N = 150, 7.3%), which are responsible for resistance to aminoglycoside, tetracycline, and sulfonamide, respectively. Additionally, 1060 (51.5%) isolates carried multiple plasmid transfer genes associated with IncFIB-FIC(FII) plasmids. Other plasmid types found in at least 1% of the strains included IncI1 (N = 101, 4.9%), IncHI2 (N = 62, 3.0%), or IncHI1 (N = 24, 1.2%). The virulence gene profiles of human isolates showed diversity but largely overlapped with those from different food sources. Notably, the aerobactin iron acquisition genes, associated with Salmonella's virulence and colonization, were highly prevalent among chicken isolates (N = 1019, 89.0%) but less frequent in isolates from other sources (N = 65, 7.2%). IncFIB-FIC(FII) plasmids, commonly harboring the aerobactin operon, were highly prevalent among chicken-related isolates and present in about 10% of human isolates. The diverse plasmid, AMR, and virulence gene profiles in human-associated isolates suggest that multiple factors may contribute to the increased virulence in S. Schwarzengrund.

Relationship of biofilm formation with antibiotic resistance, virulence determinants and genetic diversity in clinically isolated Acinetobacter baumannii strains in Karachi, Pakistan.

Multi-drug resistant (MDR) Acinetobacter baumannii causes nosocomial infections due to a plethora of virulence determinants like biofilm formation which are pivotal to its survival and pathogenicity. Hence, investigation of these mechanisms in currently circulating strains is required for effective infection control and drug development. This study investigates the prevalence of antibiotic resistance and virulence factors and their relationship with biofilm formation in Acinetobacter baumannii strains in Karachi, Pakistan. Enterobacterial Repetitive Intergenic Consensus Polymerase Chain Reaction (ERIC PCR) was used for observing genetic variations. The results revealed that 100% A. baumannii strains were MDR and 74.4% had multiple antibiotic resistance index (MARi) of 0.875-1. There were 27 biofilm forming strains with a moderate correlation between biofilm formation and MARi. A high prevalence of abaI (86.04%), bfmR (95.3%), bfmS (97.6%), csuE (90.69%), ompA (74.4%), and pgaA virulence genes (95.3%) and resistance genes adeF (53.4%), adeJ (74.4%), ampC (51.1%), tem-1 (51.1%), and vim (65.1%)) were observed in these strains. ERIC PCR revealed that 5 of 22 genetic types had strong biofilm form strains with similar virulence genes profiles. Conclusively, the study shows escalated resistance and virulence in clinical strains which warrants consistent epidemiological studies to prevent infections spread and future outbreaks.

Incidence and virulence gene profiling of Pseudomonas aeruginosa in broiler chickens from Fayoum Governorate, Egypt

Incidence and virulence gene profiling of Pseudomonas aeruginosa in broiler chickens from Fayoum Governorate, Egypt

Antimicrobial resistance, virulence gene profiling, and genetic diversity of multidrug-resistant Pseudomonas aeruginosa isolates in Mazandaran, Iran

BackgroundPseudomonas aeruginosa is a major cause of healthcare-associated infections (HAIs), particularly in immunocompromised patients, leading to high morbidity and mortality rates. This study aimed to investigate the antimicrobial resistance patterns, virulence gene profiles, and genetic diversity among P. aeruginosa isolates from hospitalized patients in Mazandaran, Iran.MethodsFrom September 2021 to April 2022, 82 non-duplicate P. aeruginosa isolates were collected from diverse clinical sources. Identification was confirmed using API 20 NE (bioMérieux, Marcy l’Etoile, France). Antimicrobial susceptibility testing was conducted using the Kirby-Bauer disk diffusion method according to CLSI guidelines to assess resistance to a range of antibiotics. The virulence profile (exoT, exoY, exoU, toxA, plcH, plcN, algD, aprA, lasB and exoS) of each P. aeruginosa isolate was determined by PCR. The genetic diversity among the strains was evaluated using the random amplification of polymorphic DNA (RAPD) technique. Clustering was based on a Dice similarity coefficient of ≥ 85%.ResultsOf the 82 total strains, P. aeruginosa exhibited the highest and lowest resistance toward ticarcillin-clavulanate (98.78%) and colistin (0%), respectively. Moreover, 100% of the P. aeruginosa isolates were MDR. The following prevalence of virulence factor genes was observed: aprA, lasB, algD, toxA, plcH, exoY, and exoT in 100% of isolates. The plcN, exoS, and exoU were identified 98.78%, 67.07%, and 45.12%, respectively. The RAPD patterns obtained with primers 272 and 208 had respectively 2–19 and 6–17 bands. According to the Dice similarity coefficient of higher than 85%, 56 and 39 clusters were recognized.ConclusionThe high rate of multidrug resistance combined with the widespread presence of virulence genes in P. aeruginosa isolates highlights the potential for increased infection severity, morbidity, and mortality in hospitalized patients. The substantial genetic diversity observed among isolates suggests that P. aeruginosa in this region may rapidly evolve, necessitating ongoing surveillance and more targeted antimicrobial strategies.Clinical trial numberNot applicable.

Characterization of an Enterococcus sp. SMC-9 strain isolated from bile of a patient with cholangitis.

The genus Enterococcus is increasingly recognized for its involvement in various human infections, with several species known to be pathogenic. This study characterized Enterococcus sp. SMC-9, isolated from bile of a patient with cholangitis, and compared its characteristics with those of Enterococcus montenegrensis CoE-012-22T, recently isolated from dried beef sausage. A comprehensive analysis, encompassing phylogenetic, genomic, and phenotypic studies, confirmed that strain SMC-9 belongs to the same species as E. montenegrensis CoE-012-22T. However, comparative genomic analysis revealed key differences in virulence and antibiotic resistance gene profiles between the two strains. Notably, genes related to exopolysaccharide biosynthesis and the L-rhamnose biosynthesis pathway were found exclusively in strain SMC-9, suggesting their role in the strain's colonization of the biliary tract and its involvement in cholangitis. Additionally, the tetracycline resistance gene tet(M), which was absent in E. montenegrensis CoE-012-22T, was identified in strain SMC-9, explaining its high tetracycline minimum inhibitory concentration (>16 μg/mL). These findings highlight the unique pathogenic traits of strain SMC-9 compared to E. montenegrensis CoE-012-22T. Our study underscores the significant genetic and phenotypic variations that can exist among strains within the same species, highlighting the critical need for strain typing to assess their potential impact on patient outcomes and public health.

Evolution and zoonotic risk of O1:K1 and O2:K1 avian pathogenic Escherichia coli.

The O1 and O2 serogroups of avian pathogenic E. coli (APEC) and human extraintestinal pathogenic E. coli (huExPEC) are closely related, but their evolutionary relationships need to be further elucidated. This study classified nineteen O1 and O2 APEC into rpoB sequence types (RSTs) and compared them with reference huExPEC using molecular prophage typing, virulence and antibiotic resistance gene profiling, and comparative genomics. Most O1:K1 and O2:K1 APEC (73.7%) were classified as RST46-1 and RST47-9. RST47-9 is unique to Korean O1 APEC and likely derives from RST46-1 APEC. The six APEC showed high genome coverage/identity with the Korean RST46-1 huExPEC. Based on RST network and comparative genomics, we hypothesized that the O1 antigen first appeared in RST19-1 and O2 in RST24-1 E. coli in humans. Then, O1 and O2-antigen horizontally transferred to human RST46-1, where a unique K1 capsule (K1-cps) first appeared. The Korean APEC and huExPEC share evolutionary CRISPR spacers but differ in molecular antibiograms and prophage contents. Thus, RST46-1 huExPEC transmitted and evolved in poultry. The zoonotic risks remain unknown, but the substantial virulence of the RST46-1 APEC indicates that the reverse zoonotic risk of huExPEC in poultry is alarming.

Antimicrobial resistance, virulence gene profiles, and molecular epidemiology of enterococcal isolates from patients with urinary tract infections in Shanghai, China.

This study highlighted the critical need to understand Enterococcal strains causing UTIs in Shanghai, given their high prevalence. By assessing antimicrobial resistance profiles, virulence gene presence, and molecular epidemiology, the research offered valuable insights into the local epidemiology of Enterococcus faecalis and Enterococcus. faecium. Identifying linezolid-resistant strains, all of which carry the optrA gene, including the first report of ST300 in China and recognizing dominant MLST types, such as ST16 and ST179 for E. faecalis and ST78 for E. faecium, are vital for guiding treatment and addressing the challenges these infections present. The data emphasize the need for ongoing surveillance and customized therapeutic approaches to combat emerging resistance and virulence factors in Enterococcal UTIs.

Arcobacter species isolated from human stool samples, animal products, ready-to-eat salad mixes, and ambient water: prevalence, antimicrobial susceptibility, and virulence gene profiles

IntroductionArcobacter species are emerging foodborne pathogens increasingly associated with human illness worldwide. They are commonly found in the gastrointestinal tracts of animals and are frequently isolated from various food sources, including raw meat, poultry, and seafood. The aim of this study is to investigate the antimicrobial resistance patterns of Arcobacter spp. isolated from human stool samples, animal products, ready-to-eat salad mixes, and ambient water, assess the presence of resistance genes, and explore their potential implications for public health.MethodsIn this study, a total of 683 samples were collected from the Shahrekord area over a 12-month period. Samples were obtained from human stool, chicken meat, raw cow milk, RTE salad mixes, and environmental water sources. Two different methods were used to detect Arcobacter, depending on the sample type: bacteriological isolation and identification, and molecular identification. After identification, antimicrobial susceptibility testing was conducted. Polymerase chain reaction (PCR) was used to identify ten putative Arcobacter virulence and resistance genes.FindingsThe results revealed that Arcobacter spp. were present in 26.06% (178 out of 683) of the tested samples, with varying isolation rates across different sample types. A. butzleri being the most commonly isolated species across all sample types, while A. cryaerophilus was restricted to RTE salads, surface waters, and chicken meat. Notably, A. skirrowii was only isolated from chicken meat and environmental water. The differences of Arcobacter spp. in prevalence between the sample types were statistically significant (p < 0.05), and no significant seasonal variation was found across the sampling periods (p > 0.05). PCR analysis for ten putative virulence genes indicated that the cadF gene was present in all Arcobacter isolates. Similarly, 83.33% of the tested strains harbored the ciaB gene, while other genes were less frequently detected. Regarding resistance genes, tet(O) (7.69%) was the most identified gene, followed by blaOXA-61 (4.37%).ConclusionIn conclusion, this study highlights the alarming prevalence of antimicrobial resistance in Arcobacter spp. Monitoring Arcobacter spp. resistance can be achieved through surveillance, risk assessments, antibiotic stewardship in agriculture, public education, research collaborations, rapid diagnostics, and harmonized policies, all aimed at reducing contamination and safeguarding public health effectively.

First Detection of Vibrio parahaemolyticus in Migratory Birds in Egypt: Antibiogram, Virulence, and Resistance Gene Profiles Indicating Zoonotic and Public Health Risks.

This study examined the occurrence of Vibrio parahaemolyticus obtained from migrating birds, marking the first instance of such research conducted in Egypt. The study assessed potential risks using an antibiogram, virulence characteristics, antibiotic-resistance, and gene profile. Randomly collected 80 samples were tested for V. parahaemolyticus. Eleven (13.75%) samples were V. parahaemolyticus-contaminated. All isolates were positive for 16SrRNA and species-specific toxR genes. Interestingly, our strain is genetically similar to human and shrimp isolates, suggesting zoonotic transmission may pose a health danger. All isolates had 100% l-lysine decarboxylase, 45.45% beta-hemolytic, and 100% l-ornithine decarboxylase activity. All isolates displayednol-arginine decarboxylase activity. Notably, every isolate possessed a minimum of two virulence genes. In addition, the profiles of virulence genes were identified, tdh + /trh + (27.3%), tdh-/trh + (27.3%), and tdh + /trh- (45.4%). Out of the V. parahaemolyticus isolates, 18.2% (2/11) were extensively drug-resistant (XDR) to six different antimicrobials classes and possessed the blaTEM, blaOXA, sul1, and tetA genes. Furthermore, 63.6% of the isolates displayed multidrug resistance (MDR). The correlation highlights a strong relationship between phenotypic and genotypic resistance. Besides thestrong correlation between virulence and resistance genes.In summary, this work highlighted the presence of newly identified MDR and XDR V. parahaemolyticus carried toxR, trh, and tdh virulence genes, as well as blaTEM, blaOXA, sul1, and tetA resistance genes in migratory birds, indicating a significant public health risk.

Escherichia coli in betel leaves: prevalence, virulence characterization and antibiogram

Escherichia coli is a significant foodborne pathogen, frequently linked to hemorrhagic diarrhea, especially in developing nations, where it presents considerable public health concerns. This study was conducted to examine the virulence gene profiles and antibiotic resistance patterns of E. coli strains isolated from piper betel leaves. A total of 100 betel leaf samples, including fresh (n = 60) and ready-to-eat (n = 40) specimens, were collected and tested for the presence of E. coli using standard diagnostic techniques, such as selective culture methods, staining, latex agglutination, and polymerase chain reaction (PCR) assays. Further, the identified E. coli isolates underwent PCR-based testing for virulence genes and disk diffusion assays to assess antibiotic susceptibility. Among the 100 samples screened, 4% (n = 4/100; 95% CI: 1.57–9.84; P = 0.1126) were identified as E. coli O157, and 33% (n = 33/100; 95% CI: 24.56–42.69; P = 0.4011) were classified as non-O157 isolates. The virulence gene stx1 was found in 10.81% of isolates, while stx2, eaeA, and hlyA genes were not detected in any samples. Antibiotic resistance analysis showed that all isolates (100%, 37/37) were resistant to amoxicillin and erythromycin, with 75.68% (28/37) demonstrating resistance to tetracycline. Notably, all isolates were fully susceptible to ceftriaxone and ciprofloxacin. A majority (72.97%, 27/37) of isolates were sensitive to streptomycin, and 67.57% (25/37) were sensitive to gentamicin. Additionally, 86.48% of the E. coli isolates exhibited multidrug resistance (MDR), showing 10 resistance patterns, including 8 MDR patterns. The most common MDR pattern was AMX-TE-E, observed in 56.76% (21/37) of isolates. One isolate demonstrated resistance to six of the eight tested antibiotics across four distinct classes, with the resistance pattern AMX-TE-GEN-S-E-AZM. The MAR indices for E. coli isolates ranged between 0.25 and 0.75. These findings highlight the significant threat posed to global public health by multidrug-resistant shiga toxin-producing E. coli found on piper betel leaves in urban environments. Asian Australas. J. Biosci. Biotechnol. 2024, 9(3), 33-44

Environmental Drivers of the Divergence of Harveyi Clade Pathogens with Distinctive Virulence Gene Profiles.

Fish and shellfish pathogens of the Harveyi clade of the Vibrio genus cause significant losses to aquaculture yields and profits, with some of them also causing infections in humans. The present study aimed to evaluate the presence of Harveyi clade fish and shellfish pathogens and their possible diversification in response to environmental drivers in southeastern USA waters. The presence and abundance of potential pathogens were evaluated via the detection and quantitation of six Harveyi-clade-specific virulence genes (toxR, luxR, srp, vhha, vhh, and vhp; VGs) in environmental DNA with clade-specific primers. The environmental DNA was obtained from water and sediments collected from three Georgia (USA) cultured clam and wild oyster grounds. In sediments, the VG concentrations were, on average, three orders of magnitude higher than those in water. The most and least frequently detected VGs were vhp and toxR, respectively. In water, the VGs split into two groups based on their seasonal trends. The first group, composed of luxR, vhp, vhha, and vhh, peaked in August and remained at lower concentrations throughout the duration of the study. The second group, composed of toxR and srp, peaked in June and disappeared between July and December. The first group revealed a high adaptation of their carriers to an increase in temperature, tolerance to a wide range of pH, and a positive correlation with salinity up to 25 ppt. The second group of VGs demonstrated a lower adaptation of their carriers to temperature and negative correlations with pH, salinity, potential water density, conductivity, and dissolved solids but a positive correlation with turbidity. No such trends were observed in sediments. These data reveal the role of VGs in the adaptability of the Harveyi clade pathogens to environmental parameters, causing their diversification and possibly their stratification into different ecological niches due to changes in water temperature, acidity, salinity, and turbidity. This diversification and stratification may lead to further speciation and the emergence of new pathogens of this clade. Our data urge further monitoring of the presence and diversification of Harveyi clade pathogens in a global warming scenario.

Molecular Characterization and Antibiogram of &lt;i&gt;Pseudomonas aeruginosa&lt;/i&gt; Isolated from Fish Sold in Markets of Tirupati, India

Pseudomonas aeruginosa is an emerging opportunistic pathogen and is one of the pathogens in the acronym ESKAPE representing a global threat to human health associated with antimicrobial resistance. The present study aimed for molecular characterization, virulence gene profiling and antimicrobial resistance studies of P. aeruginosa isolated from 200 fish samples collected from different fish markets in Tirupati, Andhra Pradesh, India. Of the 200 fish samples screened, 30.5% were confirmed as P. aeruginosa by PCR, targeting the 16S rRNA gene. Among the positive isolates, it was found that 70.4% and 75.4% of the isolates harbored toxA and exoS virulence markers, respectively. All 61 P. aeruginosa isolates recovered were phenotypically characterized for antimicrobial resistance patterns by the disc diffusion method. The study has found 100% resistance against erythromycin followed by 98.4% resistance to amoxicillin, 91.8% resistance against tetracycline, 88.5% resistance to vancomycin and cotrimoxazole, 45.9% resistance to ciprofloxacin, 44.2% resistance against cefepime and 9.9% resistance to gentamicin. The MAR indices were in the range from 0.5 to 1.0. The prevalence of multiple antibiotic resistance of P. aeruginosa harboringvirulence genes in fish can pose a serious threat and hazard to public health through the consumption of raw or undercooked fish.

Virulence plasmid with IroBCDN deletion promoted cross-regional transmission of ST11-KL64 carbapenem-resistant hypervirulent Klebsiella pneumoniae in central China

BackgroundCarbapenem-resistant and hypervirulent Klebsiella pneumoniae (CR-hvKP) caused infections of high mortality and brought a serious impact on public health. This study aims to evaluate the epidemiology, resistance and virulence characteristics of CR-hvKP and to identify potential drivers of cross-regional transmission in different regions of China, in order to provide a basis for developing targeted prevention measures.MethodsClinical K. pneumoniae strains were collected from Jiujiang and Nanchang in Jiangxi province between November 2021 to June 2022. Clinical data of patients (age, sex, source of infection, and diagnosis) were also gathered. We characterized these strains for their genetic relatedness using PFGE, antimicrobial and virulence plasmid structures using whole-genome sequencing, and toxicity using Galleria mellonella infection model.ResultsAmong 609 strains, 45 (7.4%) CR-hvKP were identified, while the strains.isolated from Nanchang and Jiujiang accounted for 10.05% (36/358) and 3.59% (9/251). We observed that ST11-KL64 CR-hvKP had an overwhelming epidemic dominance in these two regions. Significant genetic diversity was identified among all ST11-KL64 CR-hvKP cross-regional transmission between Nanchang and Jiujiang and this diversity served as the primary driver of the dissemination of clonal groups. Virulence genes profile revealed that ST11-KL64 CR-hvKP might harbour incomplete pLVPK-like plasmids and primarily evolved from CRKP by acquiring the hypervirulence plasmid. We found the predominance of truncated-IncFIB/IncHI1B type virulence plasmids with a 25 kb fragment deletion that encoded iroBCDN clusters.ConclusionST11-KL64 is the most cross-regional prevalent type CR-hvKPs in Jiangxi province, which mainly evolved from CRKPs by acquiring a truncated-IncHI1B/IncFIB virulence plasmid with the deletion of iroBCDN. Stricter surveillance and control measures are urgently needed to prevent the epidemic transmission of ST11-KL64 CR-hvKP.

Escherichia coli and Enterobacteriaceae Counts, Virulence Gene Profile, Antimicrobial Resistance, and Biofilm Formation Capacity during Pig Slaughter Stages.

This study aimed to count Enterobacteriaceae and Escherichia coli in different locations on pig carcasses (shank, loin, abdomen, shoulder, and jowl) from two slaughterhouses (A and B) between September 2019 and July 2021 during different slaughter stages (after bleeding, after passing through the epilator machine, after manual toileting in the dirty area, before and after evisceration, and after the final washing), as well as verify antimicrobial resistance and biofilm formation capacity. The main points of Enterobacteriaceae and E. coli contamination were identified in the two slaughterhouses through three collections. The stages with the highest counts were post-bleeding and evisceration in both slaughterhouses and after manual toileting in slaughterhouse B in the first collection. Most E. coli isolates were resistant to multiple antimicrobials, with higher resistance frequencies to amoxicillin, ampicillin, chloramphenicol, sulfonamides, and streptomycin. The virulence genes eae, stx1, and stx2 were also detected. Three isolates had all three genes and exhibited resistance to at least six antimicrobial classes (β-lactams, macrolides, aminoglycosides, sulfonamides, amphenicols, and quinolones). E. coli isolates also showed a high frequency of strains with moderate and strong in vitro biofilm-forming capacity. This is the first study to characterize microbial contamination by pig slaughter stage in the Federal District region, demonstrating the critical points for hygienic production. E. coli was isolated from the surface of pig carcasses, as well as the virulence genes stx1, stx2, and eae were detected. The multi-antimicrobial resistant isolates also had a moderate-to-strong biofilm formation capacity, thus demonstrating risks to public health.

Unveiling the genetic landscape of Streptococcus agalactiae bacteremia: emergence of hypervirulent CC1 strains and new CC283 strains in Tehran, Iran

BackgroundThe emergence of Streptococcus agalactiae infections in patients with bacteremia is increasing. It is crucial to investigate the epidemiology, molecular characteristics, biofilm status, and virulence analysis of Streptococcus agalactiae in these patients.MethodsIn this cross-sectional study, 61 S. agalactiae isolated from blood infection were subjected to characterization through antimicrobial susceptibility tests, biofilm formation, multilocus sequence typing (MLST), and PCR analysis for detecting resistance (tet and erm family) and virulence genes (alp2/3, alp4, bca, bac, eps, rib, lmb, cylE, and pilus island genes).ResultsOverall, 32.7% of the isolates demonstrated an inducible clindamycin resistance phenotype. The results showed that 49.2, 24.6, and 8.2% of confirmed Streptococcus agalactiae strains were classified as strong, intermediate, and weak biofilm-forming strains, respectively. tet(M) (57.1%) was recovered most, followed by tet(M) + tet(L) (14.3%), tet(S) + tet(K) (10.7%), tet(M) + tet(K) (8.9%), tet(M) + tet(K) + tet(O) (5.4%), and tet(S) + tet(L) + tet(O) (3.6%). Three virulence gene profiles of cylE, lmb, bca, rib (24.6%; 15/61), cylE, lmb, rib, alp3 (19.7%; 12/61), and cylE, lmb, bac, rib (16.4%; 10/61) were detected in approximately two-thirds of the isolates. MLST revealed that the 61 isolates belonged to six clonal complexes, including CC1 (49.2%), followed by CC12 (18%), CC19 (13.1%), CC22 (9.8%), CC17 (6.6%), and CC283 (3.3%), and 11 different sequence types (STs), including ST1 (24.6%), ST7 (14.8%), ST918 (13.1%), ST2118 (9.8%), ST19 (9.8%), ST48 (6.6%), ST1372 (4.9%), ST22 (4.9%), ST40 (4.9%), ST734 (3.3%), and ST283 (3.3%). Remarkably, all CC1 and CC12 isolates, three-fourths of CC19, and half of CC22 were confirmed as biofilm producers. Conversely, CC17 and CC28 isolates were found to be nonproducers. The occurrence of strong biofilm formation was limited to specific CCs, namely CC1 (34.4%), CC12 (8.2%), CC19 (3.3%), and CC22 (3.3%).ConclusionThe high prevalence of CC1 and CC12 clones among S. agalactiae strains reflects the emergence of these lineages as successful clones in Iran, which is a serious concern and poses a potential threat to patients.

Impact of salinity on Streptococcus agalactiae and health parameters of Oreochromis niloticus during streptococcosis outbreaks

S. agalactiae infection is one of the most important bacterial diseases imparting mass mortality in the aquaculture sector, worldwide. It is responsible for posing both economic burdens and risks of cross-infectivity and zoonotic transmission. In this aspect, this study examined the virulence gene profiles, molecular serotyping and pathogenicity of S. agalactiae strains isolated from tilapia farms in Kerala, India in 2022. Following sample collection and processing, three S. agalactiae strains (KSA/01, KSA/02, and KSA/03) were isolated and confirmed the bacterial identity using 16S rRNA sequencing. In pathogenicity test, the LD50 of the S. agalactiae was found to be 1 × 106 CFU/ml. An increase in the salinity was found to affect the pathogenicity of S. agalactiae as well as the hematological and serological profile of tilapia. Thus the presence of S. agalactiae, a highly virulent and zoonotic pathogen in tilapia farms, underscores the imperative of continuous monitoring in aquaculture facilities.