Clonal Complexes Research Articles

Genomic profiling of methicillin-sensitive Staphylococcus aureus (MSSA) isolates in Kuwait hospitals.

Staphylococcus aureus is an important pathogen that causes mild to invasive infections in hospitals and the community. Although methicillin-susceptible Staphylococcus aureus (MSSA) isolates continue to cause different infections, there is no data on the genetic backgrounds of the MSSA colonizing or causing infections in Kuwait hospitals. This study aimed to investigate MSSA isolated from patients admitted to Kuwait hospitals for antibiotic resistance and genetic backgrounds to understand their clonal composition. Consecutive MSSA isolates were collected from single patients during two surveillance periods in 2016 and 2021 in 13 public hospitals. The isolates were characterized using antibiogram, staphylococcal protein A (spa) typing, DNA microarray analysis, and multilocus sequence typing (MLST) using standard protocols. A total of 446 MSSA was cultured from different clinical samples in 2016 (n = 240) and 2021 (n = 206). All isolates were susceptible to vancomycin [minimum inhibitory concentration (MIC) ≤ 2 mg/L], teicoplanin (MIC ≤2 mg/L), linezolid (MIC ≤4 mg/L), ceftaroline (MIC ≤2 mg/L), rifampicin, and mupirocin but were resistant to erythromycin (21.3%), clindamycin (14.0%), gentamicin (3.8%), kanamycin (10.5%), fusidic acid (27.0%), tetracycline (6.9%), trimethoprim (23.1%), and ciprofloxacin (35.2%). Molecular typing identified 155 spa types, dominated by t127 (15.0%), t084 (5.4%), t3841 (5.4%), t267 (2.4%), t442 (2.2%), t091 (2.2%), t021 (2.2%), and t003 (2.2%); 31 clonal complexes (CCs); and 56 sequence types (STs). The majority of the isolates (n = 265; 59.4%) belonged to CC1 (20.6%), CC15 (10.9%), CC22 (5.1%), CC30 (7.6%), CC361 (10.1%), and CC398 (4.7%). The MSSA isolates belonged to diverse genetic backgrounds dominated by CC1, CC15, CC22, CC30, CC361, and CC398. The distribution of MSSA clones in 2016 and 2021 showed the stability of these clones over time. The study provides the first comprehensive data on the clonal distribution of MSSA in Kuwait hospitals.

Genetic markers associated with host status and clonal expansion of Group B Streptococcus in the Netherlands.

Certain Group B Streptococcus (GBS) genotypes are associated with invasive disease in neonates. We conducted a comparative genomic analysis of GBS isolates from neonatal disease and maternal carriage in the Netherlands to determine distribution of genetic markers between the two host groups. Whole genome sequencing was used to characterise 685 neonatal invasive isolates (2006-2021) and 733 maternal carriage isolates (2017-2021) collected in the Netherlands. Clonal complex (CC) 17 and serotype III were significantly more common in disease while carriage isolates were associated with serotypes II, IV, V as well as CC1. Previously reported CC17-A1 sub-lineage was dominant among disease isolates and significantly less common in carriage. The phiStag1 phage, previously associated with expansion of invasive CC17 isolates in the Netherlands, was more common among disease isolates compared to carriage isolates overall, however it was equally distributed between CC17 isolates from carriage and disease. Prevalence of antimicrobial resistance genes was overall lower in disease compared to carriage isolates, but increased significantly over time, mediated by rise in prevalence of a multidrug resistance element ICESag37 among disease isolates. There is a stable association between certain GBS genotypes and invasive disease, which suggests opportunities for developing more precise disease prevention strategies based on GBS targeted screening. In contrast, GBS mobile genetic elements appear less likely to be correlated with carriage or disease, and instead are associated with clonal expansion events across the GBS population.

Gut colonization by extended-spectrum β-lactamase-producing Escherichia coli in dairy herd in Brazil: successful dissemination of a One Health clone.

The overuse of antimicrobials in livestock has contributed to the emergence and selection of clinically relevant multidrug-resistant bacteria. In Brazil, there is no conclusive information on the occurrence of Escherichia coli producing extended-spectrum β-lactamase (ESβL) in cattle breeding, which is an important sector of agribusiness in this country. Herein, we investigated the presence of ESβL-positive E. coli strains in dairy cattle from a commercial farm with routine practice of therapeutic cephalosporins. Ninety-five rectal swab samples were collected from healthy dairy calves and cows under treatment with ceftiofur. Samples were screened for the presence of ESβL producers, and positive isolates were identified by MALDI-TOF, with subsequent screening for genes encoding ESβL variants by PCR and sequencing. The presence of ESβL (CTX-M-15)-producing E. coli was confirmed in calves, and lactating and dry cows. Most ESβL strains with genetic homologies ≥ 90% were grouped into two major PFGE clusters, confirming the suscessful expansion of clonally related lineages in animals from different lactating cycles, on the same property. Four representatives CTX-M-15-positive E. coli strains had their genomes sequenced, belonging to the clonal complex (CC) 23 and sequence type (ST) 90. A phylogeographical landscape of ST90 was performed revealing a global One Health linkage. Our results highlight the intestinal microbiota of dairy cattle as a hotspot for the spread of critical priority ESβL-producing E. coli and demonstrate that ST90 is an international clone genomically adapted to human and animal hosts, which deserve additional investigation to determine its zoonotic potential and impact in food chain.

Emergence of genetic diversity and multi-drug resistant Clostridium perfringens from wild birds

BackgroundClostridium perfringens (C. perfringens) is an important zoonotic microorganism that can cause animal and human infections, however information about the prevalence status in wild birds of this pathogenic bacterium is currently limited.ResultIn this study, 57 strains of C. perfringens were isolated from 328 fecal samples of wild birds. All the isolates were identified as type A and 70.18% of the isolates carried the cpb2 gene. Antimicrobial susceptibility testing showed that and 22.80% of the isolates were classified as multidrug-resistant strains. The MLST analysis of the 57 isolates from wild birds was categorized into 55 different sequence types (STs) and clustered into eight clonal complexes (CCs) with an average of 20.1 alleles and the Simpson Diversity index (Ds) of 0.9812, and revealed a high level of genetic diversity within the C. perfringens populations. Interestingly, the isolates from swan goose were clustered in the same CC while isolates from other bird species were more scattered suggesting that a potential difference in genetic diversity among the C. perfringens populations associated with different bird species.ConclusionC. perfringens exhibits a wide range of host adaptations, varying degrees of antimicrobial resistance, and a high degree of genetic diversity in wild birds. Understanding the prevalence, toxin type, antimicrobial resistance, and genetic diversity of C. perfringens in wildlife populations is essential for developing effective strategies for disease control and management.

Risk factors for dairy cows mastitis in Algeria, antibiotic resistance and molecular typing of the causative Staphylococcus aureus.

Adoption of a rational management in dairy farms would improve the milk quality and farmers' income. In the current study, we aimed to describe bovine mastitis in 32 dairy herds, identify the main cow- and herd-associated risk factors, and analyze both epidemiological along with molecular characteristics of Staphylococcus aureus infecting udders. Based on Californian Mastitis Test and clinical examination, the prevalence of mastitis in cows was 52.25% (116/222), of which 6.3% was clinical mastitis and 45.94% was subclinical mastitis. Overall, 218 (24.54%) quarters suffered from mastitis, whose 29.81% (65/218) infected with S. aureus. Mastitis was lowest in mid-lactation with OR = 0.371 with 95% confidence interval (CI) of 0.141-0.976, and in cows separated from their calves (OR = 0.164, 95% CI 0.056-0.477) than suckler cows. Similar results were obtained from S. aureus related mastitis. To assess the genetic lineages of S. aureus isolates, we determined clonal complexes (CC) using DNA microarray hybridization profiles and performed spa typing. The strains were assigned to nine clonal complexes, and 19 spa types; with CC97 (44.77%), and CC22 (40.29%) were the most predominant lineages and t223 (40.29%), t7136 (10.44%), t359 (8.95%) and t267 (5.97%) were the most common spa types. A total of 88.05% (n = 59) isolates were resistant to at least one tested antibiotic while only 4.47% were multi-drug resistant strains. Higher rates of resistance were observed for penicillin (86.5%) and tetracycline (14.9%) respectively. Our results show the need for adoption of feasible mastitis program with special emphasis on sub-clinical mastitis and associated risk factors.

Large-Scale S. aureus Screening with Molecular Epidemiology; the Role of MSSA and Community MRSA in Hospital Transmissions

Background: The frequency of Staphylococcus aureus transmission in hospitals is unknown: symptomatic infection may occur months after transmission and colonization, and infection prevention efforts rely on indirect measurements, rather than direct detection of transmission events. We implemented a hospital-based S. aureus screening program, combined with whole genome sequencing of S. aureus surveillance and clinical cultures and data extracted from the electronic health record, to identify S. aureus clonal complex-, patient- and location-specific factors associated with S. aureus transmission in our health system. Methods: Screening S. aureus cultures were obtained at admission by nasal swab for adults admitted to Medicine, Transplant, Oncology and intensive care, and weekly by swab of nares, axilla and groin for children admitted to intensive care and Oncology at NYU Langone Health in New York City. All methicillin-resistant S. aureus (MRSA) from screening and clinical (blood, wound, sputum) cultures and all methicillin-susceptible S. aureus (MSSA) from screening and blood cultures underwent whole genome sequencing. Isolates from distinct patients with < 2 0 single nucleotide pair differences were considered genetically related. Electronic health data was extracted for descriptive statistics and for spatiotemporal plots to assess plausible transmissions. We used REDCap electronic data capture tools hosted at NYU Grossman School of Medicine and SAS software for data analysis to evaluate S. aureus transmissions between November 2022 and November 2023. Results: We analyzed 8,567 S. aureus isolates: including 6,552 screening cultures, 1,008 blood cultures, and 1,007 clinical cultures. We found 424 plausible S. aureus hospital transmissions using sequencing and electronic health data. Screening cultures identified 75% of transmissions that would have otherwise been missed with blood and clinical cultures alone. The majority of positive screening cultures isolated MSSA, but the proportion of transmissions due to MSSA differed by age. In children, MSSA colonization accounted for 62% of transmissions. In adults, only 15% of transmissions were due to MSSA colonization, whereas MRSA colonization accounted for 56% of transmissions. Analysis of adult MRSA isolates by clonal complex found that 45% of transmissions were due to CC8, higher than the 17% among isolates agnostic of transmissions. Emergency departments and the neonatal intensive care unit had the highest number of transmissions. Patients involved in transmissions had longer lengths of stay and frequent hospitalizations. Conclusions: A S. aureus screening program, coupled with genome sequencing and electronic health data, can identify patient group, hospital locations and clonal complexes that are at high risk for S. aureus transmissions.

Analysis of molecular epidemiological characteristics and antimicrobial susceptibility of vancomycin-resistant and linezolid-resistant Enterococcus in China

BackgroundThis study investigates the distribution and characteristics of linezolid and vancomycin susceptibilities among Enterococcus faecalis (E. faecalis) and Enterococcus faecium (E. faecium) and explores the underlying resistance mechanisms.MethodsA total of 2842 Enterococcus clinical isolates from patients were retrospectively collected, and their clinical data were further analyzed. The minimum inhibitory concentrations (MICs) of vancomycin and linezolid were validated by broth dilution method. The resistance genes optrA, cfr, vanA, vanB and vanM were investigated using polymerase chain reaction (PCR). Housekeeping genes and resistance genes were obtianed through whole-genome sequencing (WGS).ResultsOf the 2842 Enterococcus isolates, 88.5% (2516) originated from urine, with E. faecium accounted for 60.1% of these. The vanA gene was identified in 27/28 vancomycin resistant Enterococcus (VRE) isolates, 4 of which carried both vanA and vanM genes. The remaining strain was vanM positive. The optrA gene was identified in all E. faecalis isolates among linezolid resistant Enterococcus (LRE). E. faecium showed a higher multiple antibiotic resistance index (MAR index) compared to E. faecalis. The multi-locus sequence typing (MLST) showed the sequence type of E. faecium mainly belongs to clonal complex (CC) 17, nearly E. faecalis isolates analyzed were differentiated into 7 characteristics of sequence types (STs), among which ST16 of CC16 were the major lineage.ConclusionUrine was the primary source of VRE and LRE isolates in this study. E. faecium showed higher levels of resistance compared to E. faecalis. OptrA gene was detected in 91.6% of LRE, which could explain linezolid resistance, and van genes were detected in all vancomycin resistant Enterococcus strains, while vanA was a key resistance mechanism in VRE identified in this study.

Time-calibrated phylogenetic and chromosomal mobilome analyses of Staphylococcus aureus CC398 reveal geographical and host-related evolution

An international collection of Staphylococcus aureus of clonal complex (CC) 398 from diverse hosts spanning all continents and a 30 year-period is studied based on whole-genome sequencing (WGS) data. The collection consists of publicly available genomic data from 2994 strains and 134 recently sequenced Swiss methicillin-resistant S. aureus (MRSA) CC398 strains. A time-calibrated phylogeny reveals the presence of distinct phylogroups present in Asia, North and South America and Europe. European MRSA diverged from methicillin-susceptible S. aureus (MSSA) at the beginning of the 1950s. Two major European phylogroups (EP4 and EP5), which diverged approximately 1974, are the main drivers of MRSA CC398 spread in Europe. Within EP5, an emergent MRSA lineage spreading among the European horse population (EP5-Leq) diverged approximately 1996 from the pig lineage (EP5-Lpg), and also contains human-related strains. EP5-Leq is characterized by staphylococcal cassette chromosome mec (SCCmec) IVa and spa type t011 (CC398-IVa-t011), and EP5-Lpg by CC398-SCCmecVc-t011. The lineage-specific antibiotic resistance and virulence gene patterns are mostly mediated by the acquisition of mobile genetic elements like SCCmec, S. aureus Genomic Islands (SaGIs), prophages and transposons. Different combinations of virulence factors are present on S. aureus pathogenicity islands (SaPIs), and novel antimicrobial resistance gene containing elements are associated with certain lineages expanding in Europe. This WGS-based analysis reveals the actual evolutionary trajectory and epidemiological trend of the international MRSA CC398 population considering host, temporal, geographical and molecular factors. It provides a baseline for global WGS-based One-Health studies of adaptive evolution of MRSA CC398 as well as for local outbreak investigations.

Utilizing whole genome sequencing to characterize Listeria spp. persistence and transmission patterns in a farmstead dairy processing facility and its associated farm environment

Farmstead dairy processing facilities may be particularly susceptible to Listeria spp. contamination due to the close physical proximity of their processing environments (PE) to associated dairy farm environments (FE). In this case study, we supported the implementation of interventions focused on improving (i) cleaning and sanitation efficacy, (ii) hygienic zoning, and (iii) sanitary equipment/facility design and maintenance in a farmstead dairy processing facility, and evaluated their impact on Listeria spp. detection in the farmstead's PE over 1 year. Detection of Listeria spp. in the farmstead's PE was numerically reduced from 50% to 7.5% after 1 year of intervention implementation, suggesting that these interventions were effective at improving Listeria spp. control. In addition, environmental samples were also collected from the farmstead's FE to evaluate the risk of the FE as a potential source of Listeria spp. in the PE. Overall, detection of Listeria spp. was higher in samples collected from the FE (75%, 27/36) compared with samples collected from the PE (24%, 29/120). Whole genome sequencing (WGS) performed on select isolates collected from the PE and FE supported the identification of 6 clusters (range of 3 to 15 isolates per cluster) that showed ≤ 50 high quality single nucleotide polymorphism (hqSNP) differences. Of these 6 clusters, 3 (i.e., clusters 2, 4, and 5) contained isolates that were collected from both the PE and FE, suggesting that transmission between these 2 environments was likely. Moreover, all cluster 2 isolates represented a clonal complex (CC) of L. monocytogenes commonly associated with dairy farm environmental reservoirs (i.e., CC666), which may support that the farmstead's FE represented an upstream source of the cluster 2 isolates that were found in the PE. Overall, our data underscore that, while the FE can represent a potential upstream source of Listeria spp. contamination in a farmstead dairy processing facility, implementation of targeted interventions can help effectively minimize Listeria spp. contamination in the PE.

Insights into Aspergillus fumigatus Colonization in Cystic Fibrosis and Cross-Transmission between Patients and Hospital Environments.

Approximately 60% of individuals with cystic fibrosis (CF) are affected by Aspergillus fumigatus infection. This condition is correlated with a decline in lung function and is identified as an independent risk factor contributing to hospital admissions among CF patients. This study investigates the dynamic interplay of A. fumigatus within the context of CF patients, tracing its evolution over time, with a specific emphasis on colonization dynamics. An analysis was conducted on 83 sequential A. fumigatus isolates derived from sputum samples of six patients receiving care at a renowned CF hospital in Brazil. Employing microsatellite genotyping techniques, alongside an investigation into cyp51A gene mutations, this research sheds light on the genetic variations, colonization, and resistance of A. fumigatus within the CF respiratory environment. Our research findings indicate that CF patients can harbor A. fumigatus strains from the same clonal complexes for prolonged periods. Additionally, we identified that clinical isolates have the potential to spread among patients in the same healthcare facility, evidencing hospital contamination. Two patients who underwent long-term Itraconazole treatment did not show phenotypic resistance. However, one of these patients exhibited mutations in the cyp51A gene, indicating the need to monitor resistance to azoles in these patients colonized for long periods by A. fumigatus. We also observed co-colonization or co-infection involving multiple genotypes in all patients over time. This comprehensive examination offers valuable insights into the pathogenesis of A. fumigatus infections in CF patients, potentially shaping future therapeutic strategies and management approaches. This enhanced understanding contributes to our knowledge of A. fumigatus impact on disease progression in individuals with cystic fibrosis. Additionally, the study provides evidence of cross-contamination among patients undergoing treatment at the same hospital.

First Insight into the Whole Genome Sequencing Whole Variations in Mycobacterium bovis from Cattle in Morocco.

Six cattle heads which tested positive against bovine tuberculosis (bTB) in Morocco were investigated to confirm the disease and to determine the source(s) of infection. Polymerase Chain Reaction (PCR) was directly performed on tissue samples collected from slaughtered animals. All investigated animals tested positive to PCR for the Mycobacterium bovis sub-type. Bacteriological isolation was conducted according to the technique recommended by WOAH for the cultivation of the Mycobacterium tuberculosis Complex (MBTC). Whole genome sequencing (WGS) was carried out on six mycobacterial isolates and the phylogenic tree was constructed. The six Moroccan isolates fit with clades II, III, IV, V and VII and were confirmed to belong to the clonal complexes Eu2, Unknown 2 and 7 as well as to sublineages La1.7.1, La1.2 and La1.8.2. The significant Single Nucleotide Polymorphism (SNPs) ranged from 84 to 117 between the isolates and the reference M. bovis strain and from 17 to 212 between the six isolates. Considering the high resolution of WGS, these results suggests that the source of infection of the bTB could be linked to imported animals as five of the investigated reactor animals were imported a few months prior. WGS can be a useful component to the Moroccan strategy to control bTB.

Insights into the molecular basis of reduced vancomycin susceptibility among three prominent Staphylococcus aureus clonal complexes.

Our understanding of the mechanisms that underlie the development of vancomycin-intermediate Staphylococcus aureus (VISA) is incomplete. To provide a more comprehensive view of this process, we compared genome sequences of clonal complex (CC) 5, CC8, and CC45 VISA clinical isolates and measured changes in the transcriptomes of these isolates during culture with a subtherapeutic concentration of vancomycin. Notably, we identified differentially expressed genes that were lineage-specific or common to the lineages tested, including genes that have not been previously reported to contribute to a VISA phenotype. Changes in gene expression were accompanied by reduced growth rate, increased cell wall thickness, and reduced susceptibility to daptomycin, televancin, tigecycline, and vancomycin. Our results provide support to the idea that changes in gene expression contribute to the development of VISA among three CCs that are a prominent cause of human infections.

Prediction by genetic MATS of 4CMenB vaccine strain coverage of invasive meningococcal serogroup B isolates circulating in Taiwan between 2003 and 2020.

Neisseria meningitidis serogroup B (NmB) strains have diverse antigens, necessitating methods for predicting meningococcal serogroup B (MenB) vaccine strain coverage. The genetic Meningococcal Antigen Typing System (gMATS), a correlate of MATS estimates, predicts strain coverage by the 4-component MenB (4CMenB) vaccine in cultivable and non-cultivable NmB isolates. In Taiwan, 134 invasive, disease-causing NmB isolates were collected in 2003-2020 (23.1%, 4.5%, 5.2%, 29.8%, and 37.3% from individuals aged ≤11 months, 12-23 months, 2-4 years, 5-29 years, and ≥30 years, respectively). NmB isolates were characterized by whole-genome sequencing and vaccine antigen genotyping, and 4CMenB strain coverage was predicted using gMATS. Analysis of phylogenetic relationships with 502 global NmB genomes showed that most isolates belonged to three global hyperinvasive clonal complexes: ST-4821 (27.6%), ST-32 (23.9%), and ST-41/44 (14.9%). Predicted strain coverage by gMATS was 62.7%, with 27.6% isolates covered, 2.2% not covered, and 66.4% unpredictable by gMATS. Age group coverage point estimates ranged from 42.9% (2-4 years) to 66.1% (≤11 months). Antigen coverage estimates and percentages predicted as covered/not covered were highly variable, with higher estimates for isolates with one or more gMATS-positive antigens than for isolates positive for one 4CMenB antigen. In conclusion, this first study on NmB strain coverage by 4CMenB in Taiwan shows 62.7% coverage by gMATS, with predictable coverage for 29.8% of isolates. These could be underestimated since the gMATS calculation does not consider synergistic mechanisms associated with simultaneous antibody binding to multiple targets elicited by multicomponent vaccines or the contributions of minor outer membrane vesicle vaccine components.IMPORTANCEMeningococcal diseases, caused by the bacterium Neisseria meningitidis (meningococcus), include meningitis and septicemia. Although rare, invasive meningococcal disease is often severe and can be fatal. Nearly all cases are caused by six meningococcal serogroups (types), including meningococcal serogroup B. Vaccines are available against meningococcal serogroup B, but the antigens targeted by these vaccines have highly variable genetic features and expression levels, so the effectiveness of vaccination may vary depending on the strains circulating in particular countries. It is therefore important to test meningococcal serogroup B strains isolated from specific populations to estimate the percentage of bacterial strains that a vaccine can protect against (vaccine strain coverage). Meningococcal isolates were collected in Taiwan between 2003 and 2020, of which 134 were identified as serogroup B. We did further investigations on these isolates, including using a method (called gMATS) to predict vaccine strain coverage by the 4-component meningococcal serogroup B vaccine (4CMenB).

Implication of genotypes for prognosis of Candida glabrata bloodstream infections.

Genotyping isolates of a specific pathogen may demonstrate unique patterns of antimicrobial resistance, virulence or outcomes. However, evidence for genotype-outcome association in Candida glabrata is scarce. We aimed to characterize the mycological and clinical relevance of genotypes on C. glabrata bloodstream infections (BSIs). Non-duplicated C. glabrata blood isolates from hospitalized adults were genotyped by MLST, and further clustered by the unweighted pair group method with arithmetic averages (UPGMA). A clonal complex (CC) was defined by UPGMA similarities of >90%. Antifungal susceptibility testing was performed by a colorimetric microdilution method and interpreted following CLSI criteria. Of 48 blood isolates evaluated, 13 STs were identified. CC7 was the leading CC (n = 14; 29.2%), including 13 ST7. The overall fluconazole and echinocandin resistance rates were 6.6% and 0%, respectively. No specific resistance patterns were associated with CC7 or other CCs. Charlson comorbidity index (adjusted OR, 1.49; 95% CI, 1.05-3.11) was the only predictor for CC7. By multivariable Cox regression analyses, CC7 was independently associated with 28 day mortality [adjusted HR (aHR), 3.28; 95% CI, 1.31-8.23], even after considering potential interaction with neutropenia (aHR, 3.41; 95% CI, 1.23-9.42; P for interaction, 0.24) or limited to 34 patients with monomicrobial BSIs (aHR, 2.85; 95% CI, 1.15-7.08). Also, the Kaplan-Meier estimate showed greater mortality with CC7 (P = 0.003). Fluconazole resistance or echinocandin therapy had no significant impact on mortality. Our data suggested comorbid patients were at risk of developing CC7 BSIs. Further, CC7 was independently associated with worse outcomes.

Genetic Complexity of CC5 Staphylococcus aureus Isolates Associated with Sternal Bursitis in Chickens: Antimicrobial Resistance, Virulence, Plasmids, and Biofilm Formation.

Sternal bursitis, a common inflammatory condition in poultry, poses significant challenges to both animal welfare and public health. This study aimed to investigate the prevalence, antimicrobial resistance, and genetic characteristics of Staphylococcus aureus isolates associated with sternal bursitis in chickens. Ninety-eight samples were collected from affected chickens, and 24 S. aureus isolates were identified. Antimicrobial susceptibility testing revealed resistance to multiple agents, with a notable prevalence of aminoglycoside resistance genes. Whole genome sequencing elucidated the genetic diversity and virulence profiles of the isolates, highlighting the predominance of clonal complex 5 (CC5) strains. Additionally, biofilm formation assays demonstrated moderate biofilm production capacity among the isolates. These findings underscore the importance of vigilant monitoring and targeted interventions to mitigate the impact of sternal bursitis in poultry production systems.

Phenotypic and genotypic characteristics of mecA - positive oxacillin-sensitive Staphylococcus aureus isolated from patients with bloodstream infection in a tertiary hospital in Southern Brazil.

Staphylococcus aureus are extremely important microorganisms, either from an epidemiological point of view or as a pathogen, responsible for causing a series of infectious processes, whether simple, restricted to the skin, or invasive infections such as bacteremia. The emergence of Oxacillin Sensitive-Methicillin Resistant S.aureus (OS-MRSA) isolates has imposed difficulties in the treatment of patients with staphylococcal infection, as such isolates can be mistakenly classified as sensitive and lead to failure of the therapy used. Thus, the objective of this study is to evaluate the prevalence, and genotypic and phenotypic characteristics, of OS-MRSA isolates, from bloodstream infections, collected from patients admitted to a hospital in southern Brazil, as well as to evaluate the treatment used. For this, 801 unique isolates of S. aureus, collected from blood cultures, between January 2011 and December 2020 were evaluated. Of these, 96 isolates were classified as sensitive to oxacillin. The isolates were identified and had their sensitivity profile performed by manual and automated methods. The minimum inhibitory concentration for vancomycin, daptomycin, oxacillin, linezolid and teicoplanine was performed by e-test. The mecA, vanA genes, typing of the SCCmec elements, as well as the search for the icaA, tst-1 and pvl virulence genes were performed by PCR. Biofilm formation was performed using the crystal violet technique. The Sequence Type (ST), as well as the Clonal Complex (CC) of the isolates was evaluated by the RTq -PCR. The clinical characteristics of the patients were evaluated through an active search in medical records. After investigating the mecA gene, 27.1% (26/96) of the isolates were considered OS-MRSA, with SCCmec type I being the most prevalent, 46.1% (12/26). Among the evaluated isolates, 41% (9/22) were included in CC5 and ST9. As for virulence, all isolates were positive for the icaA gene and characterized as strong biofilm formers. The pvl gene was found in 92.3% (24/26) of the isolates and the toxic shock syndrome toxin was present in 61.5% of the isolates (16/26). All isolates were negative for the presence of the van A gene. As for the clinical outcome, 73% (19/26) of the patients were discharged from the hospital and 27% (7/26) died. It was possible to observe a high frequency of OS-MRSA isolates causing bloodstream infections. Furthermore, such isolates contain several virulence genes, which may contribute to a worse clinical outcome.

Host specificity and virulence of Flavobacterium psychrophilum: a comparative study in ayu (Plecoglossus altivelis) and rainbow trout (Oncorhynchus mykiss) hosts

Flavobacterium psychrophilum, the causative agent of bacterial cold-water disease, is a devastating, worldwide distributed, fish pathogen causing significant economic loss in inland fish farms. Previous epidemiological studies showed that prevalent clonal complexes (CC) differ in fish species affected with disease such as rainbow trout, coho salmon and ayu, indicating significant associations between particular F. psychrophilum genotypes and host species. Yet, whether the population structure is driven by the trade of fish and eggs or by host-specific pathogenicity is uncertain. Notably, all F. psychrophilum isolates retrieved from ayu belong to Type-3 O antigen (O-Ag) whereas only very few strains retrieved from other fish species possess this O-Ag, suggesting a role in outbreaks affecting ayu. Thus, we investigated the links between genotype and pathogenicity by conducting comparative bath infection challenges in two fish hosts, ayu and rainbow trout, for a collection of isolates representing different MLST genotypes and O-Ag. Highly virulent strains in one host species exhibited low to no virulence in the other. F. psychrophilum strains associated with ayu and possessing Type-3 O-Ag demonstrated significant variability in pathogenicity in ayu, ranging from avirulent to highly virulent. Strikingly, F. psychrophilum strains retrieved from rainbow trout and possessing the Type-3 O-Ag were virulent for rainbow trout but not for ayu, indicating that Type-3 O-Ag alone is not sufficient for pathogenicity in ayu, nor does it prevent pathogenicity in rainbow trout. This study revealed that the association between a particular CC and host species partly depends on the pathogen’s adaptation to specific host species.

Genomic characterization and resistance features of Streptococcus agalactiae isolated from non-pregnant adults in Shandong, China

BackgroundStreptococcus agalactiae is a recognized pathogen that primarily affects infants and pregnant women. However, its increasingly important role in causing invasive infections among non-pregnant adults has become a significant health concern due to the severity and variety of its clinical impacts. MethodsNonduplicate S. agalactiae clinical strains associated with clinical infections (n = 139) were isolated from non-pregnant adults in Shandong, China. Antibiotic susceptibility testing, whole-genome sequencing and genomic analyses were conducted to characterize the genome and identify resistance features of these strains. ResultsThe strains exhibited universal susceptibility to penicillin, ampicillin, cefotaxime, meropenem, linezolid and vancomycin. Notably, high resistance rates were observed for erythromycin (91.4%), clindamycin (89.2%), levofloxacin (84.2%), tetracycline (54.0%) and, to a lesser extent, chloramphenicol (12.9%). Serotyping revealed seven serotypes and one non-typeable strain. Serotypes Ia, Ib, III and V predominated, representing 95.7% of the strains. Nineteen sequence types were categorized into seven clonal complexes, with CC10 being the most prevalent at 48.9%. The resistance genes mreA (100%), ermB (70.5%) and tetM (46.0%) were commonly detected. All the isolates carried at least one pilus backbone determinant and one alpha-like protein gene, with the PI-1+PI-2a and the bca gene being the most frequent at 84.2% and 54.7%, respectively. ConclusionsWhile S. agalactiae strains in non-pregnant adults retain sensitivity to β-lactam antibiotics, the elevated resistance to erythromycin, clindamycin, levofloxacin and tetracycline is concerning. Given the growing elderly population worldwide, the burden of S. agalactiae infections is significant. Continuous surveillance of serotype distribution and antibiotic resistance patterns is imperative for targeted prevention and therapeutic strategies.

Comparative Genomics of an Emerging Multidrug-Resistant blaNDM-Carrying ST182 Lineage in Enterobacter cloacae Complex.

Enterobacter cloacae, E. hormaechei and related subspecies remain the most clinically relevant among the Enterobacter cloacae complex (ECC). Carbapenemase-producing ECC strains are increasingly identified in hospital-acquired infections and usually belong to four main multilocus sequence types (MLST STs) named ST114, ST93, ST90 and ST78. Instead, ST182 has been sporadically reported among E. hormaechei strains, and recently, outbreaks of blaNDM-producing ST182 clonal strains have emerged. Herein, we aimed to investigate the presence of ST182 and explore its evolution and modes of blaNDM acquisition. A phylogenetic analysis of 646 MLST STs identified among 4685 E. hormaechei whole-genome sequencing (WGS) assemblies deposited in public repositories was performed, as well as an in silico comparative and phylogenomic analyses for 55 WGS assemblies of ST182. blaNDM-harboring contigs were also compared to published plasmid sequences. ST182 E. hormaechei strains were recovered from patients on five continents during 2011-2021. They were divided into three major genomic clusters, comprising a separate clonal complex with six other STs. In 30 out of 55 ST182 WGS assemblies, blaNDM-harboring structures were identified that were similar to the plasmids predominant in Gram-negative bacteria, harboring resistance genes to multiple antibiotic classes and virulence genes. No associations between the genomic clusters and the country/continent of isolation or the presence and the plasmid types of the blaNDM-harboring contigs were observed. Our findings show that ST182 E. hormaechei strains have been identified in the past decade worldwide; 54.5% of them carried diverse blaNDM genetic structures, suggesting recent acquisition of the blaNDM alleles. Thus, blaNDM-harboring ST182 is an emerging multidrug-resistant and virulent lineage in ECC strains that requires close monitoring.

Genomic characterization of Staphylococcus aureus isolated from patients admitted to intensive care units of a tertiary care hospital: epidemiological risk of nasal carriage of virulent clone during admission.

We conducted a molecular epidemiological study of Staphylococcus aureus using whole-genome sequence data and clinical data of isolates from nasal swabs of patients admitted to the intensive care unit (ICU) of Hiroshima University hospital. The relationship between isolate genotypes and virulence factors, particularly for isolates that caused infectious diseases during ICU admission was compared with those that did not. The nasal carriage rates of methicillin-resistant S. aureus (MRSA) and methicillin-susceptible S. aureus (MSSA) in patients admitted to the ICU were 7.0% and 20.1%, respectively. The carriage rate of community-acquired (CA)-MRSA was 2.3%, accounting for 32.8% of all MRSA isolates. Whole-genome sequencing analysis of the MRSA isolates indicated that most, including CA-MRSA and healthcare-associated (HA)-MRSA, belonged to clonal complex (CC) 8 [sequence type (ST) 8] and SCCmec type IV. Furthermore, results for three disease foci (pneumonia, skin and soft tissue infection, and deep abscess) and the assessment of virulence factor genes associated with disease conditions [bacteremia, acute respiratory distress syndrome (ARDS), disseminated intravascular coagulopathy (DIC), and septic shock] suggested that nasal colonization of S. aureus clones could represent a risk for patients within the ICU. Particularly, MRSA/J and MSSA/J may be more likely to cause deep abscess infection; ST764 may cause ventilation-associated pneumonia, hospital-acquired pneumonia and subsequent bacteremia, and ARDS, and tst-1-positive isolates may cause DIC onset.IMPORTANCENasal colonization of MRSA in patients admitted to the intensive care unit (ICU) may predict the development of MRSA infections. However, no bacteriological data are available to perform risk assessments for Staphylococcus aureus infection onset. In this single-center 2-year genomic surveillance study, we analyzed all S. aureus isolates from nasal swabs of patients admitted to the ICU and those from the blood or lesions of in-patients who developed infectious diseases in the ICU. Furthermore, we identified the virulent clones responsible for causing infectious diseases in the ICU. Herein, we report several virulent clones present in the nares that are predictive of invasive infections. This information may facilitate the design of preemptive strategies to identify and eradicate virulent MRSA strains, reducing nosocomial infections within the ICU.