Nasal carriage of Staphylococcus aureus in healthy dairy cows in Algeria: antibiotic resistance, enterotoxin genes and biofilm formation.

BACKGROUND: Staphylococcus aureus can colonize and infect a variety of animal species. In dairy herds, it is one of the leading causes of mastitis cases. The objective of this study was to characterize the S. aureus isolates recovered from nasal swabs of 249 healthy cows and 21 breeders of 21 dairy farms located in two provinces of Algeria (Tizi Ouzou and Bouira). METHODS: The detection of enterotoxin genes was investigated by multiplex PCRs. Resistance of recovered isolates to 8 antimicrobial agents was determined by disc-diffusion method. The slime production and biofilm formation of S. aureus isolates were assessed using congo-red agar (CRA) and microtiter-plate assay. Molecular characterization of selected isolates was carried out by spa-typing and Multi-Locus-Sequence-Typing (MLST). RESULTS: S. aureus was detected in 30/249 (12%) and 6/13 (28.6%) of nasal swabs in cows and breeders, respectively, and a total of 72 isolates were recovered from positive samples (59 isolates from cows and 13 from breeders). Twenty-six of these isolates (36.1%) harbored genes encoding for staphylococcal enterotoxins, including 17/59 (28.8%) isolates from cows and 9/13 (69.2%) from breeders. Moreover, 49.1% and 92.3% of isolates from cows and breeders, respectively, showed penicillin resistance. All isolates were considered as methicillin-susceptible (MSSA). Forty-five (76.3%) of the isolates from cows were slime producers and 52 (88.1%) of them had the ability to form biofilm in microtiter plates. Evidence of a possible zoonotic transmission was observed in two farms, since S. aureus isolates recovered in these farms from cows and breeders belonged to the same clonal lineage (CC15-ST15-t084 or CC30-ST34-t2228). CONCLUSIONS: Although healthy cows in this study did not harbor methicillin-resistant S. aureus isolates, the nares of healthy cows could be a reservoir of enterotoxigenic and biofilm producing isolates which could have implications in human and animal health.

Confirmation of the invasive American mink (Neogale vison) as carrier of Mycobacterium bovis in southern Chile.

Bovine tuberculosis (bTB) is a chronic infectious-contagious disease with worldwide distribution, caused by the zoonotic pathogen Mycobacterium bovis. It is believed that the existence of wild cycles may hamper the success of bTB control strategies worldwide, where wildlife species could be reservoirs of this bacterial agent across their native (e.g., European badgers, wild boars) or non-indigenous (e.g., brushtail possum in New Zealand) ranges. However, further studies are required to understand the potential risk posed by non-native wildlife in becoming carriers of M. bovis in other neglected latitudes, such as the Southern Cone of South America. In this study, we performed a specific M. bovis-RD4 real-time PCR (qPCR) assay to detect bacterial DNA in tissues from the invasive American mink (Neogale vison) in Los Ríos region, Chile. We detected M. bovis DNA in blood samples collected from 13 out of 186 (7 %) minks with known sex and age. We did not find any significant differences in bacterial DNA detection according to mink sex and age. We found that 92 % (12/13) of specimens were positive in lung, 39 % (5/13) in mediastinal lymph node, and 15 % (2/13) in mesenteric lymph node, which suggest that both respiratory and digestive pathways as possible routes of transmission between infected hosts and minks. Our study is the first report on M. bovis molecular detection in invasive minks in an area where the largest cattle population in the country is located. Furthermore, this area is characterized by a low within-herd prevalence of M. bovis infection in cattle, with a relatively low number of infected herds, and so far, no attempts at eradicating the disease have been successful.

Staphylococcal carriage among captive dingoes (Canis dingo) in Victoria, Australia.

The evolutionary lineage and taxonomy of the Australian dingo is controversial, however recent genomic and gut metagenomic research has suggested that dingoes are evolutionarily distinct from modern dogs. Staphylococcus species are known commensal organisms of dogs and other mammals. In this study we took the opportunity to determine the carriage rate and antimicrobial resistance profiles of Staphylococcus species from 15 captive Australian dingoes. S. pseudintermedius was the only coagulase-positive species recovered, isolated from 6/15 (40%) and 9/13 (69%) of the animals during the 2020 (winter) and 2021 (summer) sampling times, respectively. Twenty-three coagulase-negative isolates were characterised, with S. equorum being the most frequently (20/23, 87%) recovered species. Two isolates of S. equorum had their genomes sequenced to learn more about this species. Antimicrobial resistance amongst both coagulase-positive and -negative isolates was low; with resistance to only 3 of 12 antimicrobials observed: penicillin, erythromycin, and trimethoprim. We have shown that the Australian dingo is a host organism for S. pseudintermedius much like it is in dogs, however the carriage rate was lower than has previously been reported from dogs in Australia.

Carrier state of enterotoxigenic Escherichia coli virulence markers in pigs: Effects on gut microbiota modulation and immune markers transcription.

Enterotoxigenic Escherichia coli (ETEC) causes diarrhea in pigs at early age, leading to high mortality rates and significant economic losses in the swine industry. ETEC effect on gut microbiota and immune system is mostly studied in diarrheic model under controlled laboratory conditions, however its impact on asymptomatic carriers remains unknown. Thus, we investigated whether ETEC can modulate gut microbiota or regulate the transcription of immune markers in asymptomatic pigs in farm environment. Stool samples from newborn piglets, nursery and growing pigs, and sows were screened for ETEC markers, then submitted to 16S-rDNA sequencing to explore gut microbiota composition in carriers (ETEC+) and non-carriers (ETEC-) animals. We observed a reduced α-diversity in ETEC+ animals (p < 0.05), while bacterial compositions were mostly driven by ageing (p > 0.05). Prevotella marked ETEC-carrier group, while Rikenellaceae RC9 gut group was a marker for a healthy gut microbiota, suggesting that they might be biomarker candidates for surveillance and supplementation purposes. Furthermore, we observed transcription regulation of il6 and tff2 genes in ETEC+ in newborn and nursery stages, respectively. Our findings indicate that ETEC presence modulate gut microbiota and the immune response in asymptomatic pigs; nevertheless, further studies using a probabilistic design must be performed to assess the effect of ETEC presence on gut imbalance in pigs despite the age bias.

Risk factors for meticillin-resistant Staphylococcus aureus (MRSA) carriage in MRSA-exposed household pets.

BACKGROUND: Household pets can carry meticillin-resistant Staphylococcus aureus (MRSA) introduced to the home by their human companions. Specific factors promoting pet carriage of this pathogen have not been fully elucidated. OBJECTIVE: This study evaluated MRSA cultured from pets and the home environment in households where a human infected with MRSA had been identified, and aimed to determine potential risk factors for pet MRSA carriage. MATERIALS AND METHODS: Humans diagnosed with community-associated MRSA (CA-MRSA) skin or soft-tissue infection (SSTI) in the mid-Atlantic United States were identified. One hundred forty-two dogs and cats from 57 affected households were identified of which 134 (94.4%) pets and the household environment were sampled for bacterial culture, PCR confirmation and spa-typing for MRSA strain determination. Samples were obtained 3 months later from 86 pets. RESULTS: At baseline, 12 (9.0%) pets carried MRSA. Potential risk factors associated with carriage included pet bed (environmental) MRSA contamination, flea infestation and prior antimicrobial use in the pet. Pets tended to carry human-adapted MRSA strains and spa-types of MRSA isolates cultured from pets were concordant with strains cultured from the home environment in seven of eight homes (87.5%) at baseline. CONCLUSIONS AND CLINICAL RELEVANCE: Results may inform risk-based veterinary clinical recommendations and provide evidence for selective pet testing as a possible alternative to early removal of pets from the homes of humans infected with MRSA. MRSA contamination of the home environment is likely an important risk factor for pet MRSA carriage, and household interventions should be considered to reduce risk of MRSA carriage in exposed pets.

Two In Vivo Models to Study Salmonella Asymptomatic Carrier State in Chicks.

In chicken, Salmonella Enteritidis and Salmonella Typhimurium, the two main serotypes isolated in human infections, can persist in the host organism for many weeks and up to many years without causing any symptoms. This persistence generally occurs after a short systemic infection that may either lead to death of very young birds or develop into cecal asymptomatic persistence, which is often accompanied by a high level of bacterial excretion, facilitating Salmonella transmission to counterparts. Here we describe two models of chick infection. The first model reproduces well the poultry infection in farm flocks. Numerous reinfections and animal-animal recontaminations occur leading to a high level of cecal colonization and fecal excretion in all chicks in the flock, over several weeks. In the second model, these animal reinfections and recontaminations are hampered leading to heterogeneity of infection characterized by the presence of low and super-shedders. This model allows for more mechanistic studies of Salmonella/chicks interactions as animal recontaminations are lowered.

Nasal carriage of Methicillin-Resistant Staphylococcus aureus among sympatric free-ranging domestic pigs and wild Chlorocebus pygerythrus in a rural African setting.

BACKGROUND: Methicillin Resistant Staphylococcus aureus (MRSA) nasal carriage in domestic pigs and vervet monkeys is a risk factor for subsequent severe infections in domestic pigs and for dissemination to the human population. This study assessed nasal carriage of MRSA in domestic pigs and sympatric vervet monkeys in a rural African village during an outbreak of a virus hemorrhagic fever suspected to be contracted from wild primates. This study was conducted during the 2012 Ebola outbreak to determine nasal carriage of MRSA in free-ranging domestic pigs and sympatric freely roaming vervet monkeys using conventional methods. Staphylococcus aureus (S. aureus) isolated from the anterior nares were tested for susceptibility to commonly used antibiotics and conventional PCR was used to confirm methicillin resistance. The MRSA strains were then genotyped using SCCmec typing. RESULTS: Overall, there was a high level of resistance to tetracycline [90% (63/70) in pigs and 67% (10/15) in vervet monkeys], trimethoprim/sulphamethoxazole [90% (63/70) in pigs and 67% (10/15) in vervet monkeys], and penicillin [83% (58/70) in pigs and 67% (10/15) in vervet monkeys]. Most of the MRSA strains (91.6%, 11/12) were of the SCCmec type I [1B] genotype. CONCLUSION: The nasal carriage of drug resistant S. aureus in freely roaming domestic and wild animals presents a risk for widespread environmental spread of antimicrobial resistance thus presenting a risk for treatment failure in domestic animals, wild animals, and humans.

Clinically healthy household dogs and cats as carriers of multidrug-resistant Salmonella enterica with variable R plasmids.

Introduction. Antimicrobial resistance (AMR) is a One Health issue concerning humans, animals and the environment and a unified One Health approach is required to contain this problematic issue. Dogs and cats are popular pet animals and are known to carry many bacterial pathogens that are of public health importance, including Salmonella. However, data on AMR in companion animals is limited.Gap statement. Scant AMR data from bacteria originating from companion animals limits an accurate assessment of the impacts of pet-animal-related AMR on public health.Purpose. This study aimed to phenotypically and genetically investigate AMR in Salmonella isolated from pet dogs and cats in Thailand.Methodology. Salmonella enterica were isolated from pet dogs (n=159) and cats (n=19) in Thailand between 2016 and 2019. All isolates were serotyped. Phenotypic and genotypic antimicrobial resistance was examined. PCR-based replicon typing, replicon sequence typing and plasmid multilocus sequence typing were conducted to characterize plasmids.Results. Seventy-seven serovars were identified, with serovars Weltevreden (9.6%) and Stockholm (9.0%) the most common. Most of the isolates (34.3%) were multidrug-resistant. The serovar Stockholm was an ESBL-producer and carried the ß-lactamase genes bla TEM-1 and bla CTX-M-55. The plasmid-mediated quinolone resistance (PMQR) gene, qnrS, was also detected (10.1%). Class 1 integrons carrying the dfrA12-aadA2 cassette array were most frequent (45.9%). Five plasmid replicon types as IncA/C (0.6%), N (1.1%), IncFIIA (28.7%), IncHI1 (2.2%), and IncI1 (3.4%) were identified. Based on the pMLST typing scheme (n=9), plasmids were assigned into five different STs including IncA/C-ST6 (n=1), IncH1-ST16 (n=4), IncI1-ST3 (n=1), IncI1-ST60 (n=1) and IncI1-ST136 (n=1). The ST 16 of IncHI1 plasmid was a novel plasmid ST. Subtyping F-type plasmids using the RST scheme (n=9) revealed four different combinations of replicons including S1:A-:B- (n=4), S1:A-:B22 (n=2), S3:A-:B- (n=1) and S-:A-:B47 (n=1).Conclusions. Our findings highlight the role of clinically healthy household dogs and cats as carriers of AMR Salmonella strains with different R plasmid. The implementation of AMR phenotypes instigation and genotypic monitoring and surveillance programmes in companion animals are imperative as integral components of the One Health framework.

Repeated nasopharyngeal lavage predicts freedom from silent carriage of Streptococcus equi after a strangles outbreak.

BACKGROUND: The value of repeated nasopharyngeal lavage (NPL) to detect silent carriers of Streptococcus equi has not been investigated. HYPOTHESIS/OBJECTIVES: Determine if results of serial testing for S. equi by NPL predicts subsequent true carrier status as determined by both NPL and guttural pouch lavage. ANIMALS: An outbreak of strangles with 100% morbidity in 41 mature Icelandic horses was followed prospectively to investigate development of silent carriers. All were initially positive to S. equi on NPL. The farm was closed to horse movement during the entire study. METHODS: Prospective observational study. Testing for S. equi was performed by NPL at weeks 18, 28, 29, and 30 postindex case and subsequently at week 45 by both NPL and guttural pouch lavage. Carrier status at week 45 was compared to results obtained at weeks 18, 28, 29, and 30. Descriptive statistics were calculated. Comparisons were made using Fisher's exact test or the Freeman-Halton extension with a P < .05 level of significance. RESULTS: Of 24 noncarriers at week 45, only 4 horses were negative on all 3 consecutive weekly NPL samples at weeks 28 to 30. However, 10 of the 11 horses with at least 3 negative NPL obtained from weeks 18, 28, 29, and 30 were S. equi-free at week 45 (P = .03). CONCLUSIONS AND CLINICAL IMPORTANCE: Repeated NPL on at least 3 separate occasions can assist in predicting S. equi carrier-free status in horses after recovery from a strangles outbreak.

Detecção do vírus da imunodeficiência felina em gatos domésticos (Felis catus) pela técnica de reação em cadeia da polimerase / Detection of feline immunodeficiency virus in domestic cats (Felis catus) by polymerase chain reaction technique

O objetivo deste trabalho foi detectar a presença de DNA do Vírus da Imunodeficiência Felina (FIV) em gatos domesticos (Feliz catus) assintomáticos. Foi realizada a tecnica de reação em cadeia da polimerase (PCR) em 50 animais. Para tal, foram coletadas amostras de sangue, por venopunção da jugular, de forma asséptica para armazenamento de 1-2 mL de sangue total. Os animais que participaram do estudo fizeram parte do projeto de castração "Vida digna" da Universidade Federal Rural da Amazônia. E a escolha dos animais foi realizada de maneira aleatória, sem distinção por sexo ou idade, resultando em 29 foram fêmeas e 21 machos. Para o diagnóstico, foi realizada a extração do DNA, em seguida as amostras foram testadas em duas reações de PCR utilizando- se dois conjuntos de primers do Gene gag de FIV. Achou-se uma prevalência de 2% (1/50), confirmando assim a presença do vírus na cidade de Belém. Assim, evidenciando a importância de testar os felinos mesmo sendo assintomáticos. Desta forma, faz-se necessário a realização de trabalhos futuros que amplie o número amostral dos animais testados para assim elucidar o perfil epidemiológico da doença na região de Belém do Pará, considerando a relevância clínica desta infecção e a correta conduta médica veterinária para evitar novas infecções.

The objective of this work was to detect the presence of Feline Immunodeficiency Virus (FIV) proviral DNA in asymptomatic domestic cats (Feliz catus). The polymerase chain reaction technique was performed from 50 animals. For this, blood samples were collected by jugular venipuncture, aseptically for storage of 1-2 mL of whole blood. The animals that participated in the study were part of the castration project "Vida digna" at the Universidade Federal Rural da Amazônia. And the choice of animals was performed randomly, without distinction by sex or age, resulting in 29 females and 21 males. For diagnosis, DNA extraction was performed, then the samples were tested in two PCR reactions using two sets of FIV gag gene primers. A prevalence of 2% (1/50) was observed, thus confirming the presence of the virus in the city of Belém. Thus, highlighting the importance of testing the felines even if they are asymptomatic. Therefore, it is necessary to carry out future work that expands the sample number of animals tested in order to elucidate the epidemiological profile of the disease in the region of Belém do Pará, considering the clinical relevance of this infection and the correct veterinary medical conduct to avoid new infections.

A model exploration of carrier and movement transmission as potential explanatory causes for the persistence of foot-and-mouth disease in endemic regions.

Foot-and-mouth disease (FMD) is a virulent and economically important disease of livestock, still endemic in many areas of Asia and sub-Saharan Africa. Transmission from persistently infected livestock, also known as carriers, has been proposed as a mechanism to support the persistence of FMD in endemic regions. However, whether carrier livestock can infect susceptible animals is controversial; recovered virus is infectious and there are claims of field transmission, but it remains undemonstrated experimentally. Alternate hypotheses for persistence include the movement of livestock within and between regions, and fomite contamination of the environment. Using a stochastic compartmental ordinary differential equation (ODE) model, we investigate the minimum rates of carrier transmission necessary to contribute to the maintenance of FMD in a region, and compare this to the alternate mechanism of persistence through cattle shipments. We find that carrier transmission can theoretically support persistence even at transmission rates much lower than the highest realistic rates previously proposed, and that the parameters with the most effect on the feasibility of carrier-mediated persistence are the average duration of both the carrier phase and natural immunity. However, shipment-mediated persistence remains a viable alternate mechanism for persistence without carrier transmission.

Phage Treatment Trial to Eradicate LA-MRSA from Healthy Carrier Pigs.

The increase of livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) causes a threat to human health. LA-MRSA can be transmitted from animals to animal caretakers, which may further spread MRSA to communities and health care facilities. The objective of this work was to study the efficacy of phage treatment in the eradication of LA-MRSA from healthy carrier pigs. A total of 19 MRSA -positive weanling pigs were assigned to a test (n = 10) and a control group (n = 9). A phage cocktail containing three Staphylococcus phages, or a control buffer was administered to the nares and skin of the pigs three times every two days, after which the phage and MRSA levels in nasal and skin swab samples were monitored for a three-week period. The sensitivity of the strains isolated during the follow-up period to the phage cocktail and each phage individually was analyzed and the pig sera were tested for antibodies against the phages used in the cocktail. The phage treatment did not cause any side effects to the pigs. Phages were found in the skin and nasal samples on the days following the phage applications, but there was no reduction in the MRSA levels in the sampled animals. Phage-resistant strains or phage-specific antibodies were not detected during the experiment. The MRSA load in these healthy carrier animals was only 10-100 CFU/swab or nasal sample, which was likely below the replication threshold of phages. The effectiveness of phage treatment to eradicate MRSA from the pigs could thus not be (reliably) determined.

Simultaneous and Staggered Foot-and-Mouth Disease Virus Coinfection of Cattle.

Foot-and-mouth disease (FMD) field studies have suggested the occurrence of simultaneous infection of individual hosts by multiple virus strains; however, the pathogenesis of foot-and-mouth disease virus (FMDV) coinfections is largely unknown. In the current study, cattle were experimentally exposed to two FMDV strains of different serotypes (O and A). One cohort was simultaneously infected with both viruses, while additional cohorts were initially infected with FMDV A and subsequently superinfected with FMDV O after 21 or 35 days. Coinfections were confirmed during acute infection, with both viruses concurrently detected in blood, lesions, and secretions. Staggered exposures resulted in overlapping infections as convalescent animals with persistent subclinical FMDV infection were superinfected with a heterologous virus. Staggering virus exposure by 21 days conferred clinical protection in six of eight cattle, which were subclinically infected following the heterologous virus exposure. This effect was transient, as all animals superinfected at 35 days post-initial infection developed fulminant FMD. The majority of cattle maintained persistent infection with one of the two viruses while clearing the other. Analysis of viral genomes confirmed interserotypic recombination events within 10 days in the upper respiratory tract of five superinfected animals from which the dominant genomes contained the capsid coding regions of the O virus and nonstructural coding regions of the A virus. In contrast, there were no dominant recombinant genomes detected in samples from simultaneously coinfected cattle. These findings inculpate persistently infected carriers as potential FMDV mixing vessels in which novel strains may rapidly emerge through superinfection and recombination. IMPORTANCE Foot-and-mouth disease (FMD) is a viral infection of livestock of critical socioeconomic importance. Field studies from areas of endemic FMD suggest that animals can be simultaneously infected by more than one distinct variant of FMD virus (FMDV), potentially resulting in emergence of novel viral strains through recombination. However, there has been limited investigation of the mechanisms of in vivo FMDV coinfections under controlled experimental conditions. Our findings confirmed that cattle could be simultaneously infected by two distinct serotypes of FMDV, with different outcomes associated with the timing of exposure to the two different viruses. Additionally, dominant interserotypic recombinant FMDVs were discovered in multiple samples from the upper respiratory tracts of five superinfected animals, emphasizing the potential importance of persistently infected FMDV carriers as sources of novel FMDV strains.

Multiple Mechanisms of Tigecycline Resistance in Enterobacteriaceae from a Pig Farm, China.

We isolated eight tigecycline-resistant Enterobacteriaceae strains from a pig farm in Shanghai, China, including Escherichia coli (n = 1), Proteus cibarius (n = 1), and Enterobacter hormaechei (n = 6). Two of them (E. coli and P. cibarius) were positive for tet(X). E. coli SH19PTE6 contained an IncFIA18/IncFIB(K)/IncX1 hybrid plasmid pYUSHP6-tetX, highly similar to other tet(X)-bearing hybrid plasmids from E. coli in China. In P. cibarius SH19PTE4, tet(X) was located within a new chromosomal integrative and conjugative element (ICE), ICEPciChn2, belonging to the SXT/R391 ICE family. All tigecycline-resistant E. hormaechei isolates carried the tet(A) variant; cloning and transfer of this tet(A) variant into various hosts increased their MICs for tigecycline (4- to 8-fold). Tigecycline resistance observed on a pig farm is mediated by the tet(A) variant and tet(X) via a plasmid or ICE. The rational use of antibiotics such as doxycycline and surveillance of tigecycline resistance in livestock are warranted. IMPORTANCE As a last-resort antimicrobial agent to treat serious infections, the emergence and spread of tigecycline resistance in Enterobacteriaceae and Acinetobacter have raised global concerns. Multiple mechanisms mediate tigecycline resistance in Enterobacteriaceae, such as the monooxygenase Tet(X), mutations in Tet proteins, and overexpression of efflux pumps. Although tigecycline is not approved for animals, tigecycline resistance has been observed in Escherichia coli, Proteus cibarius, and Enterobacter hormaechei isolates on a pig farm, mediated by the tet(A) variant and tet(X) via a plasmid or ICE. The heavy use of tetracyclines such as doxycycline in food-producing animals in China may be the reason for the emergence and transmission of tigecycline resistance.

Analysis of Virulence and Antimicrobial Resistance Gene Carriage in Staphylococcus aureus Infections in Equids Using Whole-Genome Sequencing.

While Staphylococcus aureus is associated with significant morbidity and mortality in equids (horses, donkeys, and mules), few studies have performed whole-genome sequencing to fully categorize large collections of equine isolates. Such sequencing allows for a comprehensive analysis of the genetic lineage and relationships of isolates, as well as the virulence genes present in each, which can be important for understanding the epidemiology of strains and their range of infections. Seventy-two clinical Staphylococcus aureus isolates from equids were collected at the Texas A&M University Veterinary Medical Teaching Hospital between 2007 and 2017. Whole-genome sequencing was performed to characterize the isolates according to sequence typing, biofilm association, antimicrobial resistance, and toxin gene carriage. Of the 72 isolates, 19% were methicillin resistant, of which the majority belonged to clonal complex 8. Eighteen distinct sequence types (STs) were represented, with the most common being ST1, ST133, ST8, and ST97. Most isolates had weak or negative overall biofilm production. Toxin and antimicrobial resistance gene carriage was varied; of note, this study revealed that a large proportion of North American equine isolates carry the leucocidin PQ toxin (66% of isolates). One isolate (17-021) carried genes imparting lincosamide and high-level mupirocin resistance, a combination not previously reported in equine-derived S. aureus isolates. IMPORTANCE This is one of the first studies to perform whole-genome sequencing (WGS) of a large collection of Staphylococcus aureus isolates, both methicillin resistant and susceptible, collected from horses. A large proportion of the isolates carry leucocidin PQ (LukPQ), making this one of the first reports of such carriage in the United States. The presence of lincosamide and high-level mupirocin resistance in a methicillin-susceptible S. aureus (MSSA) isolate highlights the importance of MSSA as a reservoir of important antimicrobial resistance genes. As microbial resistance genes on mobile genetic elements can pass between S. aureus strains and livestock-associated strains can be transferred to humans, these findings have important public health implications.

High Body Temperature is an Unlikely Cause of High Viral Tolerance in Bats.

The global SARS-CoV-2 pandemic and the role of bats in zoonotic spillover have renewed interest in the flight-as-fever hypothesis, which posits that high body temperatures experienced by bats during flight contribute to their high viral tolerance. We argue that flight-as-fever is unlikely to explain why bats harbor more viruses than other mammals on the basis of two lines of reasoning. First, flight temperatures reported in the literature overestimate true flight temperatures because of methodologic limitations. Second, body temperatures in bats are only high relative to humans, and not relative to many other mammals. We provide examples of mammals from diverse habitats to show that temperatures in excess of 40 C during activity are quite common in species with lower viral diversity than bats. We caution scientists against stating the flight-as-fever hypothesis as unquestioned truth, as has repeatedly occurred in the popular media in the wake of the SARS-CoV-2 pandemic.

S. pseudintermedius and S. aureus lineages with transmission ability circulate as causative agents of infections in pets for years.

BACKGROUND: Staphylococcus pseudintermedius (SP) and Staphylococcus aureus (SA) are common colonizers of companion animals, but they are also considered opportunistic pathogens, causing diseases of diverse severity. This study focused on the identification and characterization of 33 coagulase-positive staphylococci isolated from diseased pets (28 dogs and five cats) during 2009-2011 in a veterinary hospital in Spain in order to stablish the circulating lineages and their antimicrobial resistance profile. RESULTS: Twenty-eight isolates were identified as SP and five as SA. Nine methicillin-resistant (MR) isolates (27%) carrying the mecA gene were detected (eight MRSP and one MRSA). The 55% of SP and SA isolates were multidrug-resistant (MDR). MRSP strains were typed as ST71-agrIII-SCCmecII/III-(PFGE) A (n=5), ST68-agrIV-SCCmecV-B1/B2 (n=2), and ST258-agrII-SCCmecIV-C (n=1). SP isolates showed resistance to the following antimicrobials [percentage of resistant isolates/resistance genes]: penicillin [82/blaZ], oxacillin [29/mecA] erythromycin/clindamycin [43/erm(B)], aminoglycosides [18-46/aacA-aphD, aphA3, aadE], tetracycline [71/tet(M), tet(K)], ciprofloxacin [29], chloramphenicol [29/catpC221], and trimethoprim-sulfamethoxazole [50/dfrG, dfrK]. The dfrK gene was revealed as part of the radC-integrated Tn559 in two SP isolates. Virulence genes detected among SP isolates were as follow [percentage of isolates]: siet [100], se-int [100], lukS/F-I [100], seccanine [7], and expB [7]. The single MRSA-mecA detected was typed as t011-ST398/CC398-agrI-SCCmecV and was MDR. The methicillin-susceptible SA isolates were typed as t045-ST5/CC5 (n=2), t10576-ST1660 (n=1), and t005-ST22/CC22 (n=1); the t005-ST22 feline isolate was PVL-positive and the two t045-ST45 isolates were ascribed to Immune Evasion Cluster (IEC) type F. Moreover, the t10576-ST1660 isolate, of potential equine origin, harbored the lukPQ and scneq genes. According to animal clinical history and data records, several strains seem to have been acquired from different sources of the hospital environment, while some SA strains appeared to have a human origin. CONCLUSIONS: The frequent detection of MR and MDR isolates among clinical SP and SA strains with noticeable virulence traits is of veterinary concern, implying limited treatment options available. This is the first description of MRSA-ST398 and MRSP-ST68 in pets in Spain, as well the first report of the dfrK-carrying Tn559 in SP. This evidences that current transmissible lineages with mobilizable resistomes have been circulating as causative agents of infections among pets for years.

Dogs are carriers of Clostridioides difficile lineages associated with human community-acquired infections.

There is an increasing concern about the role of animals as reservoirs of Clostridioides difficile. In this study, we investigated prevalence, antimicrobial resistance and zoonotic potential of C. difficile in dogs. Two-hundred and twenty-five dog faecal deposits were collected from trashcans in nine public gardens. C. difficile was isolated using selective plating and enrichment culture, identified by MALDI-TOF, tested for susceptibility to seven antibiotics by E-test, and sequenced on an Illumina NextSeq platform. Genome sequences were analysed to determine multilocus sequence types and resistance and toxin gene profiles. Zoonotic potential was assessed by measuring genetic variations of core genome (cg)MLST types between canine isolates and 216 temporally and spatially related human clinical isolates from a national database. C. difficile was isolated from 11 samples (4.9%). Seven isolates were toxigenic (tcdA+, tcdB+, cdtA/B-) and belonged to the sequence types ST2, ST6, ST10 and ST42. The four non-toxigenic isolates were assigned to ST15, ST26 and one novel ST. ST2, corresponding to PCR ribotype RT014/020, was the dominating lineage (n = 4) and, together with ST26 and ST42 isolates, showed close resemblance to human isolates, i.e. 2-5 allelic differences among the 1999 genes analysed by cgMLST. Three non-toxigenic isolates displayed resistance to clindamycin, erythromycin and tetracycline mediated by erm(B) and tet(M). Resistance to metronidazole, moxifloxacine, rifampicin or vancomycin was not detected. In conclusion, a small proportion of faecal deposits contained toxigenic C. difficile such as ST2 (RT014/020), which is a major cause of community-acquired infections. Our finding suggests that pathogenic strains can be exchanged between dogs and humans.

Characterization of potential superspreader farms for bovine tuberculosis: A review.

BACKGROUND: Variation in host attributes that influence their contact rates and infectiousness can lead some individuals to make disproportionate contributions to the spread of infections. Understanding the roles of such 'superspreaders' can be crucial in deciding where to direct disease surveillance and controls to greatest effect. In the epidemiology of bovine tuberculosis (bTB) in Great Britain, it has been suggested that a minority of cattle farms or herds might make disproportionate contributions to the spread of Mycobacterium bovis, and hence might be considered 'superspreader farms'. OBJECTIVES AND METHODS: We review the literature to identify the characteristics of farms that have the potential to contribute to exceptional values in the three main components of the farm reproductive number - Rf : contact rate, infectiousness and duration of infectiousness, and therefore might characterize potential superspreader farms for bovine tuberculosis in Great Britain. RESULTS: Farms exhibit marked heterogeneity in contact rates arising from between-farm trading of cattle. A minority of farms act as trading hubs that greatly augment connections within cattle trading networks. Herd infectiousness might be increased by high within-herd transmission or the presence of supershedding individuals, or infectiousness might be prolonged due to undetected infections or by repeated local transmission, via wildlife or fomites. CONCLUSIONS: Targeting control methods on putative superspreader farms might yield disproportionate benefits in controlling endemic bovine tuberculosis in Great Britain. However, real-time identification of any such farms, and integration of controls with industry practices, present analytical, operational and policy challenges.

Failure of serological testing for antigens A and C of Streptococcus equi subspecies equi to identify guttural pouch carriers.

BACKGROUND: Serology is commonly used as a means of identifying horses that might be chronic and silent carriers of S. equi but its sensitivity is rarely examined. OBJECTIVES: The study was designed to investigate the sensitivity of serological testing for antibodies against S. equi antigens A and C to detect guttural pouch carriers of S. equi. STUDY DESIGN: Retrospective clinical study. METHODS: As part of routine surveillance and quarantine procedures horses arriving at a welfare charity quarantine unit were subject to both microbiological sampling of guttural pouches and also serological testing for antibodies directed at S. equi antigens A and C. Laboratory results and endoscopic findings were examined to determine associations between serological results and guttural pouch carriage of S. equi. RESULTS: Of 287 included horses, 9 (3.1%) were found to be guttural pouch carriers. There was no significant association between serological status and guttural pouch carriage of S. equi Only one of the nine carriers (11%) was seropositive using a cut-off of OD ≥ 0.5, and only three of nine (33%) using a cut-off of OD ≥ 0.3. MAIN LIMITATIONS: Horses examined in this study were new arrivals at a welfare centre rather than from a general, well-managed, equid population. As a retrospective clinical study, the laboratory test results could not be repeated for further confirmation. CONCLUSIONS: Caution is advised when relying on seronegativity to antigens A and C in order to discount the possibility of chronic carriage of S. equi in guttural pouches.