Predominant Serovar Research Articles

Genomic characterization of a clonal emergent Salmonella Minnesota lineage in Brazil reveals the presence of a novel megaplasmid of resistance and virulence.

Salmonella Minnesota has emerged in Brazil as the predominant serovar in poultry and poultry products, along with Salmonella Heidelberg. To understand the emergence of Salmonella Minnesota over the last few years in Brazil, we performed a comparative analysis between 69 selected S. Minnesota genomes from Pathogen Detection database and 65 clonal emergent genomes isolated from Brazil. We demonstrate the presence of multidrug resistance genes against tetracycline [tet(A)], sulfonamide (sul2), and AmpC beta-lactamase (blaCMY-2) in emergent genomes, along with the carriage of a megaplasmid of resistance and virulence (~210 kb), designated pESM (plasmid for emergent Salmonella Minnesota). pESM is an IncC/A2 plasmid predicted to increase S. Minnesota environmental tolerance to mercury (mer operon) and provide resistance to tetracycline and ampicillin due to the presence of tet(A) and blaCMY-2, respectively. Moreover, pESM carries the yersiniabactin siderophore (high-pathogenicity island of Yersinia) related to the iron uptake. The temporal inference demonstrated that the most recent common ancestor dated from ~1978 and that the clonal emergent genomes carrying the pESM belong to a completely different lineage of S. Minnesota. Our results indicate that the presence of pESM likely contributes to the emergence of S. Minnesota and is precisely related to the successful spread of this particular clonal lineage in Brazil.IMPORTANCESalmonella Minnesota has emerged in Brazil as one of the leading serovars related to human and animal infection, presenting high virulence and antibiotic resistance to drugs classified as the highest priority for clinical treatment in humans. This study performed whole-genome sequencing, temporal analysis, and phylogenetics to understand the genetic insights related to the emergence of Salmonella Minnesota in Brazil. Long-read sequencing has led to the identification and characterization of a unique megaplasmid carrying virulence, antibiotic resistance, and heavy-metal tolerance genes, which may play a central role in S. Minnesota's successful emergence in Brazil and possibly worldwide. The potentially high transmissibility of this plasmid between clones and serovars represents a risk to public health since its acquisition may increase Salmonella's fitness, virulence, resistance, and persistence. Understanding the genetic aspects related to the emergence of serovars can help devise measures to mitigate the spread of hazardous multidrug-resistant strains.

Serovar and sequence type distribution and phenotypic and genotypic antimicrobial resistance of Salmonella originating from pet animals in Chongqing, China.

A total of 334 Salmonella isolates were recovered from 6,223 pet rectal samples collected at 50 pet clinics, 42 pet shops, 7 residential areas, and 4 plazas. Forty serovars were identified that included all strains except for one isolate that did not cluster via self-agglutination, with Salmonella Typhimurium monophasic variant, Salmonella Kentucky, Salmonella Enteritidis, Salmonella Pomona, and Salmonella Give being the predominant serovars. Fifty-one sequence types were identified among the isolates, and ST198, ST11, ST19, ST451, ST34, and ST155 were the most common. The top four dominant antimicrobials to which isolates were resistant were sulfisoxazole, ampicillin, doxycycline, and tetracycline, and 217 isolates exhibited multidrug resistance. The prevalence of β-lactamase genes in Salmonella isolates was 59.6%, and among these isolates, 185 harbored blaTEM, followed by blaCTX-M (66) and blaOXA (10). Moreover, six PMQR genes, namely, including qnrA (4.8%), qnrB (4.2%), qnrD (0.9%), qnrS (18.9%), aac(6')-Ib-cr (16.5%), and oqxB (1.5%), were detected. QRDR mutations (76.6%) were very common in Salmonella isolates, with the most frequent mutation in parC (T57S) (47.3%). Furthermore, we detected six tetracycline resistance genes in 176 isolates, namely, tet(A) (39.5%), tet(B) (8.1%), tet(M) (7.7%), tet(D) (5.4%), tet(J) (3.3%), and tet(C) (1.8%), and three sulfonamide resistance genes in 303 isolates, namely, sul1 (84.4%), sul2 (31.1%), and sul3 (4.2%). Finally, we found 86 isolates simultaneously harboring four types of resistance genes that cotransferred 2-7 resistance genes to recipient bacteria. The frequent occurrence of antimicrobial resistance, particularly in dogs and cats, suggests that antibiotic misuse may be driving multidrug-resistant Salmonella among pets.IMPORTANCEPet-associated human salmonellosis has been reported for many years, and antimicrobial resistance in pet-associated Salmonella has become a serious public health problem and has attracted increasing attention. There are no reports of Salmonella from pets and their antimicrobial resistance in Chongqing, China. In this study, we investigated the prevalence, serovar diversity, sequence types, and antimicrobial resistance of Salmonella strains isolated from pet fecal samples in Chongqing. In addition, β-lactamase, QRDR, PMQR, tetracycline and sulfonamide resistance genes, and mutations in QRDRs in Salmonella isolates were examined. Our findings demonstrated the diversity of serovars and sequence types of Salmonella isolates. The isolates were widely resistant to antimicrobials, notably with a high proportion of multidrug-resistant strains, which highlights the potential direct or indirect transmission of multidrug-resistant Salmonella from pets to humans. Furthermore, resistance genes were widely prevalent in the isolates, and most of the resistance genes were spread horizontally between strains.

Trends in antimicrobial susceptibility pattern of Salmonella species isolated from bacteremia patients at a tertiary care center in Northern India

The study was done to assess the antimicrobial susceptibility pattern among Salmonella enterica serovars causing bacteremia in Northern India. In this observational study, blood samples positive for Salmonella enterica serovars from January 2021 to April 2023 were studied. Species identification was done using MALDI-ToF MS. Serotyping was done using slide agglutination method. Antimicrobial susceptibility was interpreted as per the CLSI guidelines. During the study period, 32 Salmonella enterica serovars were isolated. Salmonella enterica serovar Typhi was the predominant serovar, followed by Salmonella enterica serovar Paratyphi A. All isolates were susceptible to ceftriaxone, chloramphenicol, co-trimoxazole and cefotaxime. Pefloxacin showed 100% resistance. Resistance to nalidixic acid was found in 81.2% isolates. Of the isolates resistant to nalidixic acid, 19(73.08%) isolates were resistant to ciprofloxacin also. This changing susceptibility pattern necessitates continuous surveillance of antibiogram of Salmonella isolates to rationalize the treatment protocols for invasive salmonellosis and prevent emergence of resistant strains.

Occurrence, virulence, and resistance genes in Salmonella enterica isolated from an integrated poultry company in Jordan

Salmonella is considered one of the most common foodborne pathogens worldwide. The annual number of hospitalizations and deaths related to zoonotic salmonellosis, which is transmitted from animals to humans and infects poultry and meat, is expected to be significant. Hence, the primary aims of this research were to isolate and characterize Salmonella species obtained from an integrated poultry company and identify some virulence, and antimicrobial resistance, with a specific concern about colistin resistance genes. A total of 635 samples collected from various sources in an integrated company in Jordan were screened for Salmonella species accompanying their virulence and antimicrobial resistance genes. Samples were collected from parent stock house drag swabs, broiler farms, premix, cecum at the slaughterhouse level, pre-chilling and post-chilling stages, and the final product. Salmonella species were detected in 3% (6\\200) of investigated parent stock house drag swabs, 13.8% (11/80) from cloacal swabs from broiler farms, 16.9% (11/65) from boiler farms premix, 24.4% (11/45) from the cecum at slaughterhouse level, 16.4% (9/55) from the pre-chilling stage, 37.8% (17/45) from the post-chilling stage and 53.3% (24/45) from the final product stage. No isolates were detected in feed mills (0/20), parents' premix (0/40), or hatcheries (0/40). Salmonella isolates were resistant to ciprofloxacin (91.0%), nalidixic acid (86.5%), doxycycline (83.1%), tetracycline (83.1%), sulphamethoxazole-trimethoprim (79.8%) and ampicillin (76.4%). Serotyping shows that S. Infantis was the predominant serovar, with 56.2%. Based on the minimum inhibitory concentration (MIC) test, 39.3% (35/89) of the isolates were resistant to colistin; however, no mcr genes were detected. Among antimicrobial-resistant genes, blaTEM was the most prevalent (88.8%). Furthermore, the spvC, ompA, and ompF virulence genes showed the highest percentages (97.8%, 97.8%, and 96.6%, respectively). In conclusion, Salmonella isolates were found at various stages in the integrated company. S. Infantis was the most prevalent serotype. No mcr genes were detected. Cross-contamination between poultry production stages highlights the importance of good hygiene practices. Furthermore, the presence of virulence genes and the patterns of antimicrobial resistance present significant challenges for public health.

Genomic investigation and nationwide tracking of pediatric invasive nontyphoidal Salmonella in China.

Invasive nontyphoidal Salmonella (iNTS) causes significant concern with ~15% morbidity, affecting populations mainly in African countries. However, iNTS infections among the Chinese pediatric population remain largely unknown. Here, we conducted a genomic investigation to study pediatric iNTS infections in a Chinese hospital. iNTS isolates accounted for 15.2% (18/119) of all nontyphoidal Salmonella (NTS) strains. Compared to non-iNTS isolates, iNTS isolates harbored a lower prevalence of antimicrobial-resistant genes of fluoroquinolones and β-lactams, as well as disinfectant determinants and plasmids, but carried a significantly higher prevalence of cdtB, faeCDE, and tcpC genes. Importantly, we detected an emerging serovar Goldcoast as the predominant iNTS serovar locally. By integrating 320 global Goldcoast genomes based on the One Health samplings, we conducted nationwide phylogenomic tracking and detected repeated human-to-human transmission events among iNTS cases caused by an underestimated serovar Goldcoast. Together, our exploratory genomic approach highlights a new trend in pediatric iNTS infections.

Genomic analysis of Salmonella enterica from Metropolitan Manila abattoirs and markets reveals insights into circulating virulence and antimicrobial resistance genotypes.

The integration of next-generation sequencing into the identification and characterization of resistant and virulent strains as well as the routine surveillance of foodborne pathogens such as Salmonella enterica have not yet been accomplished in the Philippines. This study investigated the antimicrobial profiles, virulence, and susceptibility of the 105 S. enterica isolates from swine and chicken samples obtained from slaughterhouses and public wet markets in Metropolitan Manila using whole-genome sequence analysis. Four predominant serovars were identified in genotypic serotyping, namely, Infantis (26.7%), Anatum (19.1%), Rissen (18.1%), and London (13.3%). Phenotypic antimicrobial resistance (AMR) profiling revealed that 65% of the isolates were resistant to at least one antibiotic, 37% were multidrug resistant (MDR), and 57% were extended-spectrum β-lactamase producers. Bioinformatic analysis revealed that isolates had resistance genes and plasmids belonging to the Col and Inc plasmid families that confer resistance against tetracycline (64%), sulfonamide (56%), and streptomycin (56%). Further analyses revealed the presence of 155 virulence genes, 42 of which were serovar-specific. The virulence genes primarily code for host immune system modulators, iron acquisition enzyme complexes, host cell invasion proteins, as well as proteins that allow intracellular and intramacrophage survival. This study showed that virulent MDR S. enterica and several phenotypic and genotypic AMR patterns were present in the food chain. It serves as a foundation to understand the current AMR status in the Philippines food chain and to prompt the creation of preventative measures and efficient treatments against foodborne pathogens.

Salmonella serovars trend in poultry Malaysia from 2011 to 2020.

Data and geographical trend of Salmonella serovars infecting poultry in Malaysia is limited. In this study, the trend of Salmonella serovars infection was presented for the past ten years from 2011 to 2020 and the predominant serovars were mapped based on geographical distribution. Analysis of passive surveillance data demonstrated a shift of Salmonella serovars that infected poultry in Malaysia. The Salmonella serovars varied within ten years of registered cases with the Veterinary Research Institute, Ipoh, Malaysia involving samples from live and dead birds. Total number of cases found from the year 2011 to 2020 were 391 cases, involving 73 Salmonella serovars with an additional one group of unclassified serovars known as Salmonella spp. Further analysis revealed that eight serovars were found predominant throughout the ten-year period. These included S. Albany, S. Braenderup, S. Brancaster, S. Corvallis, S. Enteritidis, S. Kentucky, S. Typhimurium and S. Weltevreden. Salmonella spp. (Salmonella that is incapable to be identified based on serotyping) were also one of the major groups observed throughout the years. This study could help the authorities to improvise policies for better disease control programs through the establishment of diagnostic tools for rapid Salmonella screening in poultry.

Detection and Molecular Characterization of Salmonella Enterica Serovar Enteritidis in Household Chicken Eggs: A Case Study From Erzurum, Türkiye

Salmonella enterica serovar Enteritidis (S. Enteritidis) is the most predominant serovar in poultry and eggs, and it poses a significant threat to public health worldwide as it is a leading cause of salmonellosis in humans, which is transmitted through the consumption of contaminated poultry products like eggs. The objective of this study was to evaluate the presence of S. Enteritidis in household chicken eggs collected from Erzurum Province, Türkiye. A total of 168 household chicken eggs were collected from 168 small family poultry farms. Salmonella spp. was not isolated from any of the examined egg internal contents; however, successful isolation and identification of Salmonella spp. were achieved in 4 of the shell samples. Further characterization of the identified Salmonella spp. isolates was performed at the serovar level using 16S rDNA sequence analysis, and all 4 isolates were identified as S. Enteritidis. In conclusion, this study highlights the inherent risk of S. Enteritidis contamination in household chicken eggs and emphasizes the vital significance of implementing stringent food safety measures to safeguard consumer well-being and ensure the protection of public health.

Characterization of nontyphoidal Salmonella strains from a tertiary hospital in China: serotype diversity, multidrug resistance, and genetic insights.

Nontyphoidal Salmonella is a significant public health concern due to its ability to cause foodborne illnesses worldwide. This study aims to characterize the nontyphoidal Salmonella strains isolated from patients in China. A total of 19 nontyphoidal Salmonella strains were characterized through serovar identification, antimicrobial susceptibility testing (AST), biofilm formation assessment. Genetic relatedness was determined using pulsed-field gel electrophoresis (PFGE). WGS was employed to decipher the resistance mechanism and to contextualize the S. serovar Mbandaka strains among previously sequenced isolates in China. The biofilm associated mrkA gene was examined by PCR. The predominant serovar identified was S. Enteritidis, followed by S. Mbandaka, S. Thompson, S. Livingston, S. Alachua, and S. Infantis. PFGE analysis indicated a notable genetic similarity among the S. Mbandaka isolates. Phylogenetic analysis suggested that these strains were likely derived from a single source that had persisted in China for over five years. One multidrug resistance (MDR) S. Enteritidis isolate carried a highly transferable IncB/O/K/Z plasmid with bla CTX-M-15. One S. Thompson strain, harboring the mrkABCDF operon in an IncX1 plasmid, isolated from cutaneous lesions, demonstrated robust biofilm formation. However, no mrkABCDF loci were detected in other strains. Our study emphasizes the importance of persisted surveillance and prompt response to Salmonella infections to protect public health. The dissemination of bla CTX-M-15-harboring IncB/O/K/Z plasmid and the spread of virulent mrkABCDF operon among Salmonella in China and other global regions warrant close monitoring.

Characterization of Virulence Genotypes, Antimicrobial Resistance Patterns, and Biofilm Synthesis in Salmonella spp Isolated from Foodborne Outbreaks.

Salmonella is the main bacterial pathogen that causes foodborne disease, particularly in developing countries. Nontyphoidal Salmonella (NTS) include Enteritidis and Typhimurium as the most prevalent strains which are one of the significant causes of acute gastroenteritis in children. Therefore, identifying the most predominant serovars, types of common contaminated food, and paying attention to their antibiotic resistance are the main factors in the prevention and control strategy of salmonellosis. This study was undertaken to evaluate the prevalence rate of serovars, the biofilm formation, antimicrobial resistance (AMR) status, and phenotypic virulence factors of Salmonella strains isolated from diarrhea samples in some cities of Iran. A total of 40 (10.41%) Salmonella isolates were recovered from 384 diarrhea samples processed and the most common serovar was Salmonella serovar Typhimurium (82.5). Also, all isolates belonging to serovar Typhimurium showed more virulence factors compared to other serovars. The isolates showed a high resistance rate to ampicillin (95%) and nalidixic acid (87.5%), while a low resistance rate was found for chloramphenicol (2.5%). Moreover, significant variances in the capacity of biofilm formation were found between different Salmonella serotypes. The resistance of NTS to extant choice drugs is a potential public health problem. Constant monitoring of AMR pattern and virulence profile of NTS serovars is suggested for the prevention of salmonellosis in humans.

Why do Doctors Miss the Diagnosis of Leptospiral Uveitis? Emergence of New Serovars and Challenges in Diagnosis

ABSTRACT Purpose Leptospirosis is an endemic disease in India and uveitis is its late complication. Several Indian reports showed diversity of serovars, changing patterns and existence of new serovars. Failure to add new serovars in testing panel result in increased false-negativity in serology. Aim To analyse seroprevalence, changing patterns and to discuss the resulting challenges in diagnosis. Methods In this retrospective study covering the period from 1994 to 2020, we analysed data from laboratory records of patients diagnosed with leptospiral uveitis in South India. Microscopic agglutination Test (MAT) and/or Enzyme-Linked Immunosorbent Assay (ELISA) were performed on clinically diagnosed leptospiral uveitis cases from our hospital, as well as on systemic leptospirosis patients from government and private hospitals. Results Out of a total of 87 216 new uveitis cases with varying causes over 27 years, 3,658 (4.1%) were clinically diagnosed as leptospiral uveitis. Among them, 1,268 (34.7%) patients were seropositive. In 1994, 92% of clinically diagnosed leptospirosis patients were seropositive in the MAT performed at the Centers for Disease Control and Prevention in Atlanta. However, the positivity rate gradually declined to 35% over the years. The predominant serovars identified were L. autumnalis, L. icterohaemorrhagiae, and L. australis. There were notable variations in the distribution of serovars over the years. Conclusions The data suggest a declining sensitivity of MAT and ELISA, possibly due to the emergence of new serovars. Customizing the panel based on local isolates could enhance the performance of MAT. Critical need is the addition of advanced molecular techniques to improve the diagnosis.

The serological and genetic diversity of the Leptospira interrogans Icterohaemorrhagiae serogroup circulating in the UK.

Strains of Leptospira interrogans belonging to two very closely related serovars, Icterohaemorrhagiae and Copenhageni, have been associated with disease in mammalian species and are the most frequently reported agents of human leptospirosis. They are considered the most pathogenic serovars and represent more than half of the leptospires encountered in severe human infections. Nineteen such isolates from the United Kingdom - human, domestic and wildlife species - were typed using three monoclonal antibodies (F12 C3, F70 C14 and F70 C24) in an attempt to elucidate their epidemiology. They were further examined by restriction endonuclease analysis (REA), multiple-locus variable-number tandem repeat analysis (MLVA) and lic12008 gene sequence analysis. Monoclonal antibody F12 C3, which is highly specific for Icterohaemorrhagiae and Copenhageni, confirmed that all the strains belonged to these two serovars. Sixteen strains were identified as Copenhageni and three as Icterohaemorrhagiae serovar. Only one restriction pattern type was identified, thus confirming that REA is not able to discriminate between the Icterohaemorrhagiae and Copenhageni serovars. Variable-number tandem-repeat analysis found three loci with differences in the repeat number, indicating genetic diversity between British isolates. Sequences of the lic12008 gene showed that all isolates identified as the Icterohaemorrhagiae serotype have a single base insertion, in contrast to the same sequences of the Copenhageni serotype. Copenhageni is the predominant serovar in the Icterohaemorrhagiae serogroup isolated in British Isles. There is a genetic diversity of MLVA patterns of the isolates but no genetic tool used in the study was able to determine serovars.

Seroprevalence of Leptospira infection in slaughtered cattle in Unguja Island, Zanzibar, Tanzania

Background: Leptospirosis is an important disease of global distribution affecting humans and animals in the tropical and subtropical regions caused by pathogenic Leptospira serovars. It’s an occupational disease with little information in Unguja Island, Zanzibar. Methods: A cross-sectional study was conducted in four selected slaughter facilities to determine the seroprevalence for Leptospira infection in slaughtered cattle in Unguja Island, Zanzibar. The blood samples and demographic data from 355 slaughtered cattle were collected and sera were separated for the Microscopic Agglutination Test (MAT) by using five types of Leptospira serovars; Hebdomadis, Sokoine, Lora, Grippotyphosa and Pomona with cutoff titer ≥ 1:40. The Chi-square test at p < 0.05 was used to assess the association between the variables and seropositivity of Leptospira infection. Results: The overall seroprevalence of Leptospira infection in the slaughtered cattle sampled was 13.0% (46/355). The predominant serovars from the tested serogroups were Hebdomadis (3.9%), followed by Pomona (2.8%), Grippotyphosa (2.8%), and Lora (2.3%); while the least reacted was Sokoine (1.1%). The body condition score was the only significant significant variable (χ2=103.9038, p=0.00001) associated with Leptospira infection seropositivity. Conclusion: The study offers the first report on the Leptospira seroprevalence in slaughtered cattle on Unguja Island. This might be a probable source of infection to slaughter facilities workers and other animals encroaching on the area. Therefore, precautions should be observed to prevent infection, especially for slaughter facility workers in Unguja.

Prevalence and molecular characterization of cefotaxime-resistant Salmonella strains recovered from retail meat samples in Shenzhen, China, during 2014-2017.

In this work, we collected foodborne Salmonella strains in Shenzhen, China, during 2014-2017 and investigated the genetic profile of all cefotaxime-resistant isolates in the collection. The strains were subjected to antimicrobial susceptibility tests, whole-genome sequencing, bioinformatics analysis, and conjugation studies. A total of 79 cefotaxime-resistant Salmonella were identified and found to exhibit multidrug resistance. Resistance rate recorded during the study period increased from 1.9% to 9.1%. Salmonella Typhimurium was the predominant serovar, and CTX-M family genes were dominant among the ESBLs genes detected. Notably, CTX-M-bearing plasmids or transposons often contain other drug resistance genes. Furthermore, a combination of CTX-M-55 and CTX-M-65 genes was detected for the first time in foodborne Salmonella strains. Our findings reveal the prevalence and molecular characteristics of cefotaxime-resistant foodborne Salmonella strains in southern China. IMPORTANCE Cefotaxime-resistant Salmonella strains pose an increasing threat to human health by causing infections with limited treatment options. It is therefore necessary to undertake a surveillance on the prevalence of such strains and investigate the resistance and transmission mechanisms. In this work, various ESBL genes flanked by different IS located in different mobile genetic elements were detectable among cefotaxime-resistant Salmonella strains. These data show that the high prevalence and genotypic diversity of cefotaxime-resistant foodborne Salmonella strains in China are possibly attributed to the evolution and transmission of a wide range of multidrug resistance-encoding mobile genetic elements.

Drug Resistance, Characterization and Phylogenetic Discrepancy of Salmonella enterica Isolates from Distinct Sources.

Salmonella enterica is one of the foodborne pathogens that can infect humans, spreading from one person to another by contaminated food and water. To identify the pathogenicS. entericafrom the contaminated food product, culture-based and molecular identifications, drug resistance profiling, virulence and genetic traits of the strains have been used. Herein, different animal products was subjected to screen for S. enterica prevalence, pathogenic characterization and compared with clinical Salmonella isolates (human). A total of 173 isolates from animal products and 51 isolates from clinical samples were collected.S. Typhi, S. Agona andS. Ohio were predominant serovars in blood, stool and different animal products. Both, clinical [37% (n = 19/51)] and animal product-associated isolates [21% (n = 37/173)] expressed their highest resistance to nalidixic acid. Thirty-one percentage of (n = 16/51) clinical isolates and 12% (n = 21/173) animal food-associated isolates were resistant to multiple classes of antibiotics. Class 1 integrons encoded byS. Typhi,S. Infantis andS. Emek were screened for sequence analysis, the result revealed that the cassettes encoded-aminoglycoside acetyltransferase and dihydrofolate reductase enzymes. Salmonellapathogenicity island-1 encoded-hilAgene was detected most frequently in all the isolates. PFGE profile revealed the genetic traits of the isolates which were closely linked with antibiotic-resistant properties and virulent characteristics. OnlyS. Enteritidis, collected from different samples had clonal similarities. In summary, drug-resistant pathogenicSalmonellaprevalence was observed in the animal product that could be an important alarm to consumers with the risk of enteric fever and it causes the potential risk to public health.

Dominant Salmonella Serovars in Australian Broiler Breeder Flocks and Hatcheries: a Longitudinal Study.

A longitudinal study was conducted to determine the dominance and prevalence of Salmonella enterica subsp in Australian broiler breeder flocks and hatcheries. Twenty-two flocks (n = 3339 samples) were sampled over 6 time points beginning at placement until week 40. Hatcheries (n = 274 samples) were sampled following removal of chicks hatched from eggs originating from the 22 donor parent flocks. The percent of positive flocks (36%) and frequency of positive samples (15.6%) were highest during rearing at week 7. The frequency of positive samples decreased over the 40 weeks; however, the number of positive flocks remained relatively consistent. Geographical location had a greater influence on Salmonella detection frequency than company sample origin, despite differing management and vaccination protocols within and between companies. Twelve serovars were detected in total. The predominant serovars during rearing were Salmonella Mbandaka (32%), S. Saintpaul (27%), and S. Liverpool (18%). The predominant serovars detected during production were S. Cubana (27%), S. Saintpaul (24%), and S. Havana (13%). Salmonella Typhimurium, S. Ohio, and S. Hessarek were detected in the hatcheries. Of the serovars detected, only S. Typhimurium and S. Ohio were found in both broiler breeder flocks and hatcheries. However, detection did not correspond to the status of the flock eggs feeding into the hatchery. This study provides an up-to-date capture of the current Salmonella serovars circulating in the broiler breeder industry. Continued surveillance within the Australian Chicken Meat industry is imperative to mitigate and reduce the risk of salmonellosis in the community related to chicken meat. IMPORTANCE This study identified prevalent and dominant Salmonella enterica subsp in Australian Broiler Breeder flocks, as well as in hatcheries post chick hatch and removal, from eggs originating from these donor parent flocks. The captured Salmonella data was further compared to the most common Salmonella serovars isolated from broilers, as well as human salmonellosis notification data, which is useful for consideration of the circulating serovars within the chicken meat industry and their significance in public health. As there are multiple entry points for Salmonella during the entire chicken meat production chain that can lead to carcass contamination, it is important to distinguish serovars present between the different stages of vertical integration to implement and enable Salmonella control strategies.

Seroprevalence of leptospirosis among hospitalized febrile patients in Unguja Island

Background: Leptospirosis is one of the neglected causes of febrile illness and death in developing countries, including Tanzania. The study aims to determine the seroprevalence of leptospirosis among hospitalized febrile patients in Unguja Island. Methods: A cross-sectional study was carried out in the three selected hospitals in Unguja Island between January and March 2022. A total of 402 participants with febrile illness were enrolled in the study, and blood samples were collected for sera preparation. Microscopic agglutination test (MAT) was used to detect antibodies against five Leptospira serovars, including Sokoine, Lora, Pomona, Grippotyphosa, and Hebdomadis. All sera samples reacted with MAT titers≥1:160 were counted as positive, MAT titers ranging from 1:20 to 1:80 were counted as exposed to Leptospira bacteria while the absence of agglutination was regarded as negative. The data was analyzed using SPSS version 26, 2019. Descriptive and logistic regression was performed, and p≤0.05 was considered statistically significant. Results: The mean age of study participants was 29.62 ±16.34, with a range of 0 days to 80 years. Most of them were females (64.2%) and unemployed (67.9%). The overall seroprevalence of leptospirosis was 7.7% (95% CI: 5.3-10.8). Females were 1.016 times higher likelihood to have leptospirosis (AOR = 1.016, 95% CI: 0.47-2.185, p = 0.968). Participants aged 18-35 were 2.093 times more likely to be infected with leptospirosis (AOR= 2.093, 95% CI: 0.835-5.250, p = 0.115). Participants who were unemployed (AOR = 1.169, 95% CI: 0.522-2.615, p = 0.704) revealed a significantly higher likelihood of being infected with leptospirosis. The predominant Leptospira serovars circulating among febrile patients were Sokoine 44 (10.9%), Lora 25 (6.2%), Grippotyphosa 20 (5.0%), Pomona 10 (2.5%), and Hebdomadis 9 (2.2%). Conclusion: Leptospirosis is a public health threat among febrile patients in Unguja Island; therefore, it’s important to be considered in the differential diagnosis of non-malaria febrile patients for early prevention and control strategies.

Application of a CRISPR Sequence-Based Method for a Large-Scale Assessment of Salmonella Serovars in Ontario Poultry Production Environments.

Accurate detection of all Salmonella serovars present in a sample is important in surveillance programs. Current detection protocols are limited to detection of a predominant serovar, missing identification of less abundant serovars in a sample. An alternative method, called CRISPR-SeroSeq, serotyping by sequencing of amplified CRISPR spacers, was employed to detect multiple serovars in a sample without the need of culture isolation. The CRISPR-SeroSeq method successfully detected 34 most frequently reported Salmonella serovars in pure cultures and target serovars at 104 CFU/mL in 27 Salmonella-negative environmental enrichment samples post-spiked with one of 15 different serovars, plus 2 additional serovars at 1 log CFU/mL higher abundance. When the method was applied to 442 naturally contaminated environmental samples collected from 192 poultry farms, 25 different serovars were detected from 430 of the samples. In 73.1% of the samples, 2 to 7 serovars were detected, with Salmonella Kiambu (55.7%), Salmonella Infantis (48.4%), Salmonella Kentucky (27.1%), Salmonella Livingstone (26.6%), and Salmonella Mbandaka/Montevideo (23.4%) being the most prevalent on the farms. Single isolates from 384 samples were also analyzed using a traditional serotyping method, and the same serovar identified by culture was detected by CRISPR-SeroSeq in 96.1% (369/384) of samples, with the former missing detection of additional and sometimes critical serovars. The surveillance data obtained via CRISPR-SeroSeq revealed a significant emergence of Salmonella Kiambu and Salmonella Rissen on poultry farms in Ontario. The results highlight the effectiveness of the CRISPR-SeroSeq approach in detecting multiple Salmonella serovars in poultry environmental samples under applied conditions, providing updated surveillance information on Salmonella serovars on poultry farms in Ontario. IMPORTANCE The CRISPR-SeroSeq method represents an alternative molecular tool to the traditional culture-based serotyping method that can detect multiple Salmonella serovars in a sample and provide rapid serovar results without the need of selective enrichment and culture isolation. The evaluation results can facilitate implementation of the method in routine Salmonella surveillance on poultry farms and in outbreak investigations. The application of the method can increase the accuracy of current serovar prevalence information. The results highlight the effectiveness of the validated method and the need for monitoring Salmonella serovars in poultry environments to improve current surveillance programs. The updated surveillance data provide timely information on emergence of different Salmonella serovars on poultry farms in Ontario and support on-farm risk assessment and risk management of Salmonella.

CHARACTERIZATION OF FOUR MAIN SALMONELLA SEROVARS, ALBANY, KENTUCKY, MBANDAKA, AND MONTEVIDEO, ASSOCIATED WITH CHICKEN LINES, FARMS, AND SAMPLE SOURCES IN SOUTHERN TAIWAN

Poultry and its products are often referred to as reservoirs of Salmonella to infect humans. Salmonella serovars were determined from samples of terminated eggs (early-terminated eggs, EEs, and late-terminated eggs, LEs) on farms YA (layers), YB (native hybrid broilers, NHCs), and YF (NHCs); one-day-old chicks (OCs) on farm YB; and shoe covers (SCs) on farms YB, YC (broilers), YD (broilers), YE (NHCs), and YF using multiplex PCR and agglutination methods. One hundred isolates were examined for susceptibility to 13 antimicrobials and profiles of pulsotypes and plasmids. Nine serovars were identified as serogroup B Agona and Schwarzengrund, serogroup C1 Montevideo and Mbandaka, serogroup C2 Albany, Kentucky and Newport, serogroup E Weltevreden, and serogroup G Kedougou. Different from those in 2003, Albany, Kentucky, Montevideo, and Mbandaka were the predominant serovars that differed in chromosomal and plasmid variations and antibiogram profiles. Albany and Kentucky isolates had higher resistance levels to the antimicrobials than the Montevideo and Mbandaka isolates. The antibiogram differences among the serovars may be related to the presence of antibiotic resistance genes in Salmonella genomic island 1-F (SGI1-F) and plasmids in Albany isolates. Albany and Kentucky exhibited the largest chromosomal and plasmid variations, respectively. The main serovars associated with embryogenesis termination were Mbandaka and Montevideo in EEs and LEs, Newport in NHCs, and Kedougou in LEs from layers. Furthermore, Montevideo and Agona were the only serovars detected in OCs, and Albany and Kentucky were the main serovars on SCs. Farm management also affected the Salmonella prevalence and predominant serovars.

Genetic Correlation of Virulent Salmonella Serovars (Extended Spectrum β-Lactamases) Isolated from Broiler Chickens and Human: A Public Health Concern.

This study aimed to detect the virulent Salmonella serovars (including ESBLs producing) isolated from broiler chickens and humans. Three hundred broilers and sixty human fecal samples were bacteriologically examined. Thirty (10%) and fourteen (23.4%) Salmonella isolates were recovered from broiler and human samples, respectively. The most predominant serovar was S. enteritidis and S. typhimurium. All Salmonella isolates were confirmed by conventional PCR-based invA and ompA genes. Multidrug resistant (MDR) isolates were screened for the detection of adrA and csgD biofilm-associated genes, which were found in all isolated serovars except one S. typhimurium and 2 S. infantis of chicken isolates that were devoid of the adrA gene. Moreover, MDR isolates were screened for detection of seven resistance genes including ESBLs and other classes of resistance genes. Chicken isolates harbored blaTEM, int1, blaCTX and qnrS genes as 100, 27.8, 11.1 and 11.1%, respectively, while all human isolates harbored blaTEM, int1 and int3 genes. The genetic correlations between virulent Salmonella serovars (including antimicrobial resistance) avian and human origins were compared. In conclusion, the high prevalence of virulent ESBL producing Salmonella serovars in broilers and humans with genetic correlations between them might be zoonotic and public health hazards.