Naturally acquired immunity to Plasmodium pitheci in Bornean orangutans (Pongo pygmaeus).

Naturally acquired immunity to the different types of malaria in humans occurs in areas of endemic transmission and results in asymptomatic infection of peripheral blood. The current study examined the possibility of naturally acquired immunity in Bornean orangutans, Pongo pygmaeus, exposed to endemic Plasmodium pitheci malaria. A total of 2140 peripheral blood samples were collected between January 2017 and December 2022 from a cohort of 135 orangutans housed at a natural forested Rescue and Rehabilitation Centre in West Kalimantan, Indonesia. Each individual was observed for an average of 4.3 years during the study period. Blood samples were examined by microscopy and polymerase chain reaction for the presence of plasmodial parasites. Infection rates and parasitaemia levels were measured among age groups and all 20 documented clinical malaria cases were reviewed to estimate the incidence of illness and risk ratios among age groups. A case group of all 17 individuals that had experienced clinical malaria and a control group of 34 individuals having an event of >2000 parasites µL−1 blood but with no outward or clinical sign of illness were studied. Immature orangutans had higher-grade and more frequent parasitaemia events, but mature individuals were more likely to suffer from clinical malaria than juveniles. The case orangutans having patent clinical malaria were 256 times more likely to have had no parasitaemia event in the prior year relative to asymptomatic control orangutans. The findings are consistent with rapidly acquired immunity to P. pitheci illness among orangutans that wanes without re-exposure to the pathogen.

Pharmacokinetic profile and effect on the faecal microbiome of a single dose of pradofloxacin oral suspension in the rabbit (Oryctolagus cuniculus).

Fluoroquinolones are often administered to pet rabbits given their perceived safety and limited effects on anaerobic gut microbiota. However, the pharmacokinetics and relative safety of pradofloxacin, a third-generation veterinary fluoroquinolone with a much broader spectrum of activity, have not been reported in this species. Here, we determined the pharmacokinetic profile of a single dose of oral pradofloxacin in rabbits and evaluated effects on the faecal microbiome. Four mature female rabbits were administered pradofloxacin (25 mg/ml oral suspension), at a dose of 7.5 mg/kg. The pradofloxacin median (range) Tmax was 4.50 (2.00-5.00) h, Cmax 600.66 (395.85-886.72) ng/ml and t½ was 1.27 (0.12-1.39) h. These results indicated that oral absorption of pradofloxacin was slower, and elimination faster compared with other fluoroquinolones in healthy rabbits, as well as relative to cats and dogs. Following treatment with pradofloxacin, faecal microbiota profiling showed some compositional differences between treated and control animals. This was the result of a significant decrease in the abundance of Proteobacteria, in particular bacteria belonging to the Pseudomonas, Atopostipes and Parabacteroides genera. The pharmacokinetic profile of pradofloxacin in rabbits should be further studied by increasing the sample size and using multiple-dose protocols (i.e. 7 days) to confirm safety. Further information on the effects of protein binding, higher dosages and disease on pradofloxacin pharmacokinetics in rabbits are needed before an accurate dosing regimen can be recommended.

Bacteroides caecicola sp. nov. and Bacteroides gallinaceum sp. nov., isolated from the caecum of an Indonesian chicken.

Six strains of anaerobic bacteria, C13EG70T, C13EG118, C13EG186T, C13GAMG5, C13GAMG28 and C13GAMG40, were isolated from the caecum of a healthy chicken bred in Bogor, Indonesia. Phylogenetic analysis showed the isolates were separated into two groups. Group I (C13EG70T and C13EG118) showed nearly identical 16S rRNA gene sequences (99.9 % sequence similarity). Group II (C13EG186T, C13GAMG5, C13GAMG28 and C13GAMG40) showed nearly identical 16S rRNA gene sequences (>99.4 % sequence similarity). The isolates showed low 16S rRNA gene sequence similarities to recognized species of the genus Bacteroides. High gene sequence similarities were found between type strains (C13EG70T and C13EG186T) and Bacteroides salanitronis JCM 13657T (87.9, 91.5 %, respectively). Physiological, biochemical and genotypic characteristics demonstrated that these strains could be separated from the type strain of B. salanitronis. It is concluded that Group I and Group II represent novel species. Two novel species of the genus Bacteroides are proposed as Bacteroides caecicola sp. nov. (type strain C13EG70T = LIPI12-4-Ck732T = JSAT12-4-Ck732T = InaCC B449T = NBRC 110958T) and Bacteroides gallinaceum sp. nov. (type strain C13EG186T = LIPI12-4-Ck844T = JSAT12-4-Ck884T = InaCC B451T = NBRC 110963T).

Bacteroides caecigallinarum sp. nov., isolated from caecum of an Indonesian chicken.

Three strains of anaerobic Gram-stain-negative, short to longer rod-shaped bacteria isolated from the caecum of chicken in Indonesia were studied using a polyphasic taxonomic approach. These strains belonged to the genus Bacteroides, based on sequence analysis of 16S rRNA and hsp60 (groEL) genes, with similarities of 93.2-94.1 and 89.8-90.8 %, respectively, to the closest recognized species, Bacteroides coprocola JCM 17929T. Sugar fermentation and enzyme characteristics, cellular fatty acid profiles, menaquinone profiles and metabolic end products were also investigated. Furthermore, DNA-DNA hybridization studies confirmed that the three novel strains are different from the closest related species. The strains were also found to be distinct from each other on the basis of ribotype profiles. The DNA G+C contents of the three strains were 41.1-41.8 mol%. Based on phenotypic and phylogenetic characteristics, a novel species, Bacteroides caecigallinarum sp. nov., is proposed (type strain C13EG111T = LIPI12-4-Ck773T = JSAT12-4-Ck773T = InaCC B455T = NBRC 110959T).

Potential zoonotic spillover at the human-animal interface: A mini-review.

Wildlife markets and wet wildlife markets, a type of human-animal interface, are commonly trading centers for wild-caught and captive-exotic animals as well as their products. These markets provide an ideal environment for spillovers of zoonotic and emerging infectious diseases (EIDs). These conditions may raise serious concerns, particularly in relation to wildlife species that frequently interact with humans and domestic animals. EIDs pose a significant risk to humans, ecosystems, and public health, as demonstrated by the current COVID-19 pandemic, and other previous outbreaks, including the highly pathogenic avian influenza H5N1. Even though it seems appears impossible to eliminate EIDs, we may still be able to minimalize the risks and take several measures to prevent new EIDs originated from animals. The aim of this study was to review several types of human-animal interfaces with a high risk of zoonotic spillover, infectious agents, and animal hosts or reservoirs. Identifying those factors will support the development of interventions and effective disease control in human-animal interface settings.

Possible intraindividual evolution of SARS-CoV-2 in nasopharyngeal and anal swab in an octogenarian: a case report.

Introduction: COVID-19 is an emerging infectious disease that remains to be further investigated. Case report: Here, we describe a case of COVID-19 in an octogenarian woman with comorbidities who slowly recovered during hospitalization, but died due to sudden cardiac death after 2 weeks of hospitalization. Her nasopharyngeal and anal swabs returned positive for SARS-CoV-2 by RT-PCR on day 7 of hospitalization. The NGS showed possible intraindividual evolution of virus. The sample from the nasopharyngeal swab yielded a B.1470 variant classified as clade GH. This variant showed mutation in the spike gene D614G; N gene; NS3 gene; NSP2 gene and NSP12 gene. The sample from the anal swab showed similar mutation but with additional point mutation in spike gene S12F and was classified as B.1.465 variant. Conclusions: The possibility of the gastrointestinal tract that served as reservoir for virus mutation accumulation should also be considered and the potential impact of viral fecal transmission in the environment should be further investigated.

The dynamics of circulating SARS-CoV-2 lineages in Bogor and surrounding areas reflect variant shifting during the first and second waves of COVID-19 in Indonesia.

Background: Indonesia is one of the Southeast Asian countries with high case numbers of COVID-19 with up to 4.2 million confirmed cases by 29 October 2021. Understanding the genome of SARS-CoV-2 is crucial for delivering public health intervention as certain variants may have different attributes that can potentially affect their transmissibility, as well as the performance of diagnostics, vaccines, and therapeutics. Objectives: We aimed to investigate the dynamics of circulating SARS-CoV-2 variants over a 15-month period in Bogor and its surrounding areas in correlation with the first and second wave of COVID-19 in Indonesia. Methods: Nasopharyngeal and oropharyngeal swab samples collected from suspected patients from Bogor, Jakarta and Tangerang were confirmed for SARS-CoV-2 infection with RT-PCR. RNA samples of those confirmed patients were subjected to whole genome sequencing using the ARTIC Network protocol and sequencer platform from Oxford Nanopore Technologies (ONT). Results: We successfully identified 16 lineages and six clades out of 202 samples (male n = 116, female n = 86). Genome analysis revealed that Indonesian lineage B.1.466.2 dominated during the first wave (n = 48, 23.8%) while Delta variants (AY.23, AY.24, AY.39, AY.42, AY.43 dan AY.79) were dominant during the second wave (n = 53, 26.2%) following the highest number of confirmed cases in Indonesia. In the spike protein gene, S_D614G and S_P681R changes were dominant in both B.1.466.2 and Delta variants, while N439K was only observed in B.1.466.2 (n = 44) and B.1.470 (n = 1). Additionally, the S_T19R, S_E156G, S_F157del, S_R158del, S_L452R, S_T478K, S_D950N and S_V1264L changes were only detected in Delta variants, consistent with those changes being characteristic of Delta variants in general. Conclusions: We demonstrated a shift in SARS-CoV-2 variants from the first wave of COVID-19 to Delta variants in the second wave, during which the number of confirmed cases surpassed those in the first wave of COVID-19 pandemic. Higher proportion of unique mutations detected in Delta variants compared to the first wave variants indicated potential mutational effects on viral transmissibility that correlated with a higher incidence of confirmed cases. Genomic surveillance of circulating variants, especially those with higher transmissibility, should be continuously conducted to rapidly inform decision making and support outbreak preparedness, prevention, and public health response.

Porphyromonas spp., Fusobacterium spp., and Bacteroides spp. dominate microbiota in the course of macropod progressive periodontal disease.

Macropod progressive periodontal disease (MPPD) is a necrotizing, polymicrobial, inflammatory disease commonly diagnosed in captive macropods. MPPD is characterized by gingivitis associated with dental plaque formation, which progresses to periodontitis and then to osteomyelitis of the mandible or maxilla. However, the underlying microbial causes of this disease remain poorly understood. In this study, we collected 27 oral plaque samples and associated clinical records from 22 captive Macropodidae and Potoroidae individuals that were undergoing clinical examination at Adelaide and Monarto Zoos in South Australia (15 healthy, 7 gingivitis and 5 periodontitis-osteomyelitis samples). The V3-V4 region of the 16S ribosomal RNA gene was sequenced using an Illumina Miseq to explore links between MPPD and oral bacteria in these animals. Compositional differences were detected between the microbiota of periodontitis-osteomyelitis cases compared to healthy samples (p-value with Bonferroni correction < 0.01), as well as gingivitis cases compared to healthy samples (p-value with Bonferroni correction < 0.05) using Permutational Multivariate Analysis of Variance (PERMANOVA). An overabundance of Porphyromonas, Fusobacterium, and Bacteroides taxa was also identified in animals with MPPD compared to healthy individuals using linear discriminant analysis effect size (LEfSe; p = < 0.05). An increased abundance of Desulfomicrobium also was detected in MPPD samples (LEfSe; p < 0.05), which could potentially reflect differences in disease progression. This is the first microbiota analysis of MPPD in captive macropods, and these results support a polymicrobial pathogenesis of MPPD, suggesting that the microbial interactions underpinning MPPD may be more complex than previously documented.

Genomic analysis of phylogenetic group B2 extraintestinal pathogenic E. coli causing infections in dogs in Australia.

This study investigated the prevalence of extraintestinal pathogenic E. coli (ExPEC)-associated sequence types (STs) from phylogenetic group B2 among 449 fluoroquinolone-susceptible dog clinical isolates from Australia. Isolates underwent PCR-based phylotyping and random amplified polymorphic DNA analysis to determine clonal relatedness. Of the 317 so-identified group B2 isolates, 77 underwent whole genome sequencing (WGS), whereas the remainder underwent PCR-based screening for ST complexes (STc) STc12, STc73, STc372, and ST131. The predominant ST was ST372 according to both WGS (31 % of 77) and ST-specific PCR (22 % of 240), followed by (per WGS) ST73 (17 %), ST12 (7 %), and ST80 (7 %). A WGS-based phylogenetic comparison of ST73 isolates from dogs, cats, and humans showed considerable overall phylogenetic diversity. Although most clusters were species-specific, some contained closely related human and animal (dog > cat) isolates. For dogs in Australia these findings both confirm ST372 as the predominant E. coli clonal lineage causing extraintestinal infections and clarify the importance of human-associated group B2 lineage ST73 as a cause of UTI, with some strains possibly being capable of bi-directional (i.e., dog-human and human-dog) transmission.

Companion Animals Are Spillover Hosts of the Multidrug-Resistant Human Extraintestinal Escherichia coli Pandemic Clones ST131 and ST1193.

Escherichia coli sequence types 131 (ST131) and 1193 are multidrug-resistant extraintestinal pathogens that have recently spread epidemically among humans and are occasionally isolated from companion animals. This study characterized a nationwide collection of fluoroquinolone-resistant (FQ R ) E. coli isolates from extraintestinal infections in Australian cats and dogs. For this, 59 cat and dog FQ R clinical E. coli isolates (representing 6.9% of an 855-isolate collection) underwent PCR-based phylotyping and whole-genome sequencing (WGS). Isolates from commensal-associated phylogenetic groups A (14/59, 24%) and B1 (18/59, 31%) were dominant, with ST224 (10/59, 17%), and ST744 (8/59, 14%) predominating. Less prevalent were phylogenetic groups D (12/59, 20%), with ST38 (8/59, 14%) predominating, and virulence-associated phylogenetic group B2 (7/59, 12%), with ST131 predominating (6/7, 86%) and no ST1193 isolates identified. In a WGS-based comparison of 20 cat and dog-source ST131 isolates with 188 reference human and animal ST131 isolates, the cat and dog-source isolates were phylogenetically diverse. Although cat and dog-source ST131 isolates exhibited some minor sub-clustering, most were closely related to human-source ST131 strains. Furthermore, the prevalence of ST131 as a cause of FQ R infections in Australian companion animals was relatively constant between this study and the 5-year-earlier study of Platell et al. (2010) (9/125 isolates, 7.2%). Thus, although the high degree of clonal commonality among FQ R clinical isolates from humans vs. companion animals suggests the possibility of bi-directional between-species transmission, the much higher reported prevalence of ST131 and ST1193 among FQ R clinical isolates from humans as compared to companion animals suggests that companion animals are spillover hosts rather than being a primary reservoir for these lineages.

Genomic analysis of fluoroquinolone-susceptible phylogenetic group B2 extraintestinal pathogenic Escherichia coli causing infections in cats.

Extraintestinal pathogenic Escherichia coli (ExPEC) can cause urinary tract and other types of infection in cats, but the relationship of cat ExPEC to human ExPEC remains equivocal. This study investigated the prevalence of ExPEC-associated sequence types (STs) from phylogenetic group B2 among fluoroquinolone-susceptible cat clinical isolates. For this, 323 fluoroquinolone-susceptible cat clinical E. coli isolates from Australia underwent PCR-based phylotyping and random amplified polymorphic DNA analysis to determine clonal relatedness. Of the 274 group B2 isolates, 53 underwent whole genome sequencing (WGS), whereas 221 underwent PCR-based screening for (group B2) sequence type complexes (STc) STc12, STc73, ST131, and STc372. Group B2 was the dominant phylogenetic group (274/323, 85 %), whereas within group B2 ST73 dominated, according to both WGS (43 % of 53; followed by ST127, ST12, and ST372 [4/53, 8 % each]) and ST-specific PCR (20 % of 221). In WGS-based comparisons of cat and reference human ST73 isolates, cat isolates had a relatively conserved virulence gene profile but were phylogenetically diverse. Although in the phylogram most cat and human ST73 isolates occupied host species-specific clusters within serotype-specific clades (O2:H1, O6:H1, O25:H1, O50/O2:H1), cat and human isolates were intermingled within two serotype-specific clades: O120:H31 (3 cat and 2 human isolates) and O22:H1 (3 cat and 5 human isolates). These findings confirm the importance of human-associated group B2 lineages as a cause of urinary tract infections in cats. The close genetic relationship of some cat and human ST73 strains suggests bi-directional transmission may be possible.

Diagnostic accuracy of phenotypic assays for determining antimicrobial resistance status in Staphylococcus pseudintermedius isolates from canine clinical cases.

This study evaluated the diagnostic test accuracy of disc diffusion relative to broth-microdilution for clinical Staphylococcus pseudintermedius isolated from dogs in Australia (n = 614). Accuracy of disc diffusion and broth-microdilution for oxacillin relative to mecA real-time PCR was also assessed. Each isolate had paired minimum inhibitory concentration and zone diameter values for ten antimicrobial agents. Data was dichotomised using Clinical and Laboratory Standards Institute susceptible and resistant clinical breakpoints. Test accuracy was reported using relative diagnostic sensitivity (RSe), specificity (RSp), likelihood ratio pairs, diagnostic odds ratio, and area-under-the receiver-operating characteristic (ROC AUC) analysis. Disc diffusion was found to have high test accuracy for most antimicrobials (ROC AUC range: 0.96 - 0.99) except rifampicin (ROC AUC = 0.80). The RSp of disc diffusion was high for all antimicrobials (range, 97.1%-100%). However, RSe was considerably variable (range, 35.7%-98.8%), particularly for amoxicillin-clavulanic acid (51.5%, 95% CI, 38.9%, 64.0%), cefoxitin (35.7%, 95% CI, 12.8%, 64.9%), and cephalothin (43.6%, 95% CI, 27.8%, 60.4%). When disc diffusion and broth-microdilution were compared to mecA real-time PCR, the overall accuracy of both assays was similar (ROC AUC, 0.99 respectively). However, the RSe for broth-microdilution (96.1%, 95% CI, 88.9%, 99.2%) was significantly higher than for disc diffusion (86.8%, 95% CI, 77.1%, 93.5%) (McNemars mid-p value 0.01). Overall, these findings demonstrate that for most antimicrobials, disc diffusion performed according to CLSI guidelines can be used to differentiate clinical S. pseudintermedius isolates that might otherwise be assessed by broth-microdilution, provided consideration is given to the performance estimates reported here.

Relative performance of antimicrobial susceptibility assays on clinical Escherichia coli isolates from animals.

The assessment of antimicrobial resistance in bacteria derived from animals is often performed using the disc diffusion assay. However broth-microdilution is the preferred assay for national antimicrobial resistance surveillance programs. This study aimed to evaluate the accuracy of disc diffusion relative to broth-microdilution across a panel of 12 antimicrobials using data from a collection of 994 clinical Escherichia coli isolates from animals. Disc diffusion performance was evaluated by diagnostic sensitivity, specificity, likelihood ratio pairs and receive-operating characteristic (ROC) analysis. Data was dichotomised using CLSI susceptible and resistant clinical breakpoints. In addition, disc diffusion breakpoints produced using diffusion Breakpoint Estimation Testing Software (dBETS) were evaluated. Analysis revealed considerable variability in performance estimates for disc diffusion susceptible and resistant breakpoints (AUC ranges: 0.78-0.99 and 0.92-1.0, respectively) across the panel of antimicrobials. Ciprofloxacin, tetracycline, and ampicillin estimates were robust across both breakpoints, whereas estimates for several antimicrobials including amoxicillin-clavulanic acid, cefoxitin and gentamicin were less favourable using susceptible breakpoints. Overall performance estimates were moderately improved when dBETS susceptible breakpoints were applied. For most antimicrobials, disc diffusion was accurate at predicting resistance of clinical E. coli from animals that could otherwise be determined by broth-microdilution. While disc diffusion is suboptimal for assessing the proportion of fully susceptible isolates for some drugs, sensitivity and specificity estimates provided here allow for the use of standard formula to correct this. For this reason, disc diffusion has applicability in national surveillance provided the performance of the assay is taken into account.

Characterization of Staphylococcal Cassette Chromosome mec Elements from Methicillin-Resistant Staphylococcus pseudintermedius Infections in Australian Animals.

We examined the oxacillin resistance phenotype and genomic structure of staphylococcal cassette chromosome mec (SCCmec) elements from 77 veterinary methicillin-resistant Staphylococcus pseudintermedius (MRSP) isolates. Isolates were characterized by oxacillin broth microdilution, whole-genome sequencing, and bioformatics analysis. Five previously described SCCmec elements, and a sixth novel element, were identified: SCCmec III (also known as II-III), ΨSCCmec57395, and SCCmecNA45 (a SCCmec VII variant), all previously described in MRSP, and SCCmec IVg and SCCmec VT, previously described in both methicillin-resistant Staphylococcus aureus (MRSA) and MRSP. The sixth element was novel and found among nine geographically clustered isolates. This novel pseudostaphylococcal cassette chromosome (ΨSCCmecKW21) contained a class A mec gene complex but lacked ccr genes. It also harbored heavy metal (cadmium) resistance determinants. The median oxacillin MIC values among ΨSCCmecKW21, SCCmec III, and SCCmec VT isolates were significantly higher than those determined for the SCCmecNA45 VII variant isolates and ΨSCCmec57395 and SCCmec IVg isolates. ΨSCCmecKW21 was found exclusively in sequence type 497 (ST497), an MRSP clone that is locally successful in Victoria, Australia. Future studies are necessary to determine if this clone has disseminated further afield and if ΨSCCmecKW21 has moved into other MRSP lineages or staphylococcal species.IMPORTANCEStaphylococcus pseudintermedius is a significant veterinary pathogen and occasional cause of infections in humans. ß-Lactams are an important group of antimicrobials used to treat staphylococcal infections in humans and animals. However, when staphylococci become methicillin resistant via the acquisition of a mobile genetic element called staphylococcal cassette chromosome mec (SCCmec), they become resistant to all ß-lactams. This study detected a novel SCCmec element among a cluster of methicillin-resistant S. pseudintermedius isolates from animals in Australia. It also detected SCCmec elements in S. pseudintermedius that had high similarity to those identified in methicillin-resistant Staphylococcus aureus, demonstrating how human and animal pathogens can share the same resistance determinants.

Clonal diversity and geographic distribution of methicillin-resistant Staphylococcus pseudintermedius from Australian animals: Discovery of novel sequence types.

Methicillin-resistant Staphylococcus pseudintermedius (MRSP) is an increasingly prevalent pathogen in veterinary medicine. This study examined the molecular epidemiology of clinical MRSP isolated from Australian animals. Clinical staphylococci submitted to all Australian veterinary diagnostic laboratories were collected during 2013 and identified using traditional phenotypic tests and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS). Phenotypic antimicrobial resistance was determined using broth microdilution and disk diffusion. MRSP isolates were characterized by whole genome sequencing which included identification of the mecA gene. Phylogenetic relationships were inferred by comparison of single nucleotide polymorphisms. Of the 669 S. pseudintermedius isolates collected from dogs, cats and cattle, 77 (11.5%) were MRSP. Nineteen multilocus sequence types (STs) were identified, with most isolates belonging to one of five STs (ST71, ST497, ST316, ST496 and ST45). Phylogenetic analysis revealed that Australian ST71 appears closely related to ST71 from overseas. ST497 and ST496 represented novel sequence types, not previously reported outside Australia. Most other STs were novel and only distantly related to each other. Geographical clustering of STs was observed. All isolates belonging to the five main STs were multi- to extensively- drug resistant while isolates from singleton STs generally had lower levels of antimicrobial resistance. The frequency of ciprofloxacin, trimethoprim-sulfamethoxazole, gentamicin, chloramphenicol and tetracycline resistance varied significantly between STs (p<0.01). Australian MRSP isolates are phylogenetically diverse, with a mix of previously unreported and well known international MRSP clones that demonstrate geographic clustering and exhibit both multidrug-resistant and extensively drug-resistant phenotypes.

Molecular Characterization of Methicillin-Resistant Staphylococcus aureus Isolated from Australian Animals and Veterinarians.

This study aimed to determine the frequency and molecular epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) from Australian animals and whether animal-derived MRSA was similar to that from Australian veterinarians. A total of 1,080 clinical coagulase positive Staphylococcus isolates from Australian animals were collected during 2013. Sixteen (4%) of 360 S. aureus isolates were MRSA. Most MRSA came from companion animals, while none came from livestock. MRSA isolates were characterized using whole genome sequencing. ST22-IV (EMRSA-15) was the most common clone in dogs and cats. Clonal complex (CC) 8 was most common in horses. Most ST22-IV isolates were resistant to ciprofloxacin. Animal-derived MRSA genomes were interrogated for the presence of host-specific genetic markers (staphylokinase gene [scn], chemotaxis-inhibiting proteins gene [chp], staphylococcal complement inhibitor gene [sak], enterotoxin A gene [sea], and Von Willebrand Factor binding protein gene [vwb]). A subset of MRSA genomes previously collected from Australian veterinarians was also interrogated. There was no clear pattern in the distribution of host-specific markers among animal and veterinarian isolates. Animal- and veterinarian-derived MRSA were intermingled in the phylogenetic tree. The absence of MRSA in Australian livestock is in stark contrast with its presence in livestock from other countries. Possible explanations include Australia's geographic isolation, the absence of live animal importation into Australia, and most notably, the restrictions placed on the use of antimicrobials of critical importance in Australian livestock.

Dissemination and persistence of extended-spectrum cephalosporin-resistance encoding IncI1-blaCTXM-1 plasmid among Escherichia coli in pigs.

This study investigated the ecology, epidemiology and plasmid characteristics of extended-spectrum cephalosporin (ESC)-resistant E. coli in healthy pigs over a period of 4 years (2013-2016) following the withdrawal of ESCs. High carriage rates of ESC-resistant E. coli were demonstrated in 2013 (86.6%) and 2014 (83.3%), compared to 2015 (22%) and 2016 (8.5%). ESC resistance identified among E. coli isolates was attributed to the carriage of an IncI1 ST-3 plasmid (pCTXM1-MU2) encoding blaCTXM-1. Genomic characterisation of selected E. coli isolates (n = 61) identified plasmid movement into multiple commensal E. coli (n = 22 STs). Major STs included ST10, ST5440, ST453, ST2514 and ST23. A subset of the isolates belong to the atypical enteropathogenic E. coli (aEPEC) pathotype that harboured multiple LEE pathogenic islands. pCTXM1-MU2 was similar (99% nt identity) to IncI1-ST3 plasmids reported from Europe, encoded resistance to aminoglycosides, sulphonamides and trimethoprim, and carried colicin Ib. pCTXM1-MU2 appears to be highly stable and readily transferable. This study demonstrates that ESC resistance may persist for a protracted period following removal of direct selection pressure, resulting in the emergence of ESC-resistance in both commensal E. coli and aEPEC isolates of potential significance to human and animal health.

Antimicrobial resistance in clinical Escherichia coli isolated from companion animals in Australia.

Multidrug-resistant (MDR) Escherichia coli have become a major public health concern to both humans and animal health. While the frequency of antimicrobial resistance (AMR) in clinical E. coli is monitored regularly in human medicine, current frequency of AMR in companion animals remains unknown in Australia. In this study we conducted antimicrobial susceptibility testing (AST) and where possible, determined potential risk factors for MDR infection among 883 clinical Escherichia coli isolated from dogs (n=514), cats (n=341) and horses (n=28). AST was undertaken for 15 antimicrobial agents according to the Clinical Laboratory Standards Institute (CLSI) guidelines and interpreted using epidemiological cut-off values (ECOFFs) as well as CLSI veterinary and human clinical breakpoints. The AST revealed complete absence of resistance to carbapenems while resistance to amikacin was observed at a low level in isolates from dogs (1.6%) and cats (1.5%) compared to horses (10.7%). Among dog isolates, resistance to fluoroquinolones ranged from 9.1%-9.3% whereas among cat isolates, it ranged from 3.2%-5%. Among dog isolates, the proportion showing a 3rd generation cephalosporin (3GC) non-wild type phenotype was significantly higher (P<0.05) in skin and soft tissue infection (SSTI, n=122) isolates (17.2%-20.5%) compared to urinary tract infection (UTI, n=392) isolates (9.9%-10.2%). The frequency of multidrug resistance was 18.1%, 11.7% and 42.9% in dog, cat and horse isolates, respectively. Risk factor analysis revealed that MDR E. coli isolated from UTI were positively associated with chronicity of infection and previous antimicrobial treatment. Dogs and cats with chronic UTI that had been previously treated with antimicrobials were eight times and six times more likely to be infected with MDR E. coli compared to dogs and cats with non-chronic UTI, and no history of antimicrobial treatment, respectively. This study revealed that pre-existing disease condition and prior antimicrobial use were the major risks associated with UTI with MDR E. coli in companion animals.

Antimicrobial resistance in coagulase-positive staphylococci isolated from companion animals in Australia: A one year study.

Methicillin-resistant coagulase-positive staphylococci (CoPS) have become increasingly recognised as opportunistic pathogens that limit therapeutic options in companion animals. The frequency of methicillin resistance amongst clinical isolates on an Australia-wide level is unknown. This study determined antimicrobial susceptibility patterns for CoPS isolated from clinical infections in companion animals (dogs, cats and horses) as part of the first nation-wide survey on antimicrobial resistance in animal pathogens in Australia for a one-year period (January 2013 to January 2014). Clinical Staphylococcus spp. isolates (n = 888) obtained from 22 veterinary diagnostic laboratories were identified by MALDI-TOF mass spectrometry and subjected to antimicrobial susceptibility testing for 16 antimicrobials, representing 12 antimicrobial classes. Potential risk factors associated with methicillin resistance in Staphylococcus pseudintermedius isolates from dogs were analysed based on demographic factors and clinical history, including gender, age, previous antimicrobial treatment, chronic and/or recurrent diseases and site of infections. The most commonly identified CoPS were S. pseudintermedius (70.8%; dogs n = 616, cats n = 13) and S. aureus (13.2%, horses n = 53, dogs n = 47 and cats n = 17). Overall, the frequency of methicillin resistance among S. pseudintermedius (MRSP) and S. aureus (MRSA) was 11.8% and 12.8%, respectively. MRSP isolates were strongly associated with resistance to fluoroquinolones (OR 287; 95%CI 91.2-1144.8) and clindamycin (OR 105.2, 95%CI 48.5-231.9). MRSA isolates from dogs and cats were also more likely to be resistant to fluoroquinolones (OR 5.4, 95%CI 0.6-252.1), whereas MRSA from horses were more likely to be resistant to rifampicin. In multivariate analysis, MRSP-positive status was significantly associated with particular infection sites, including surgical (OR 8.8; 95%CI 3.74-20.7), and skin and soft tissue (OR 3.9; 95%CI 1.97-7.51). S. pseudintermedius isolated from dogs with surgical site infections were three times more likely to be methicillin-resistant if cases had received prior antimicrobial treatment. Whilst the survey results indicate the proportion of CoPS obtained from Australian companion animals that are methicillin-resistant is currently moderate, the identified risk factors suggest that it could rapidly increase without adequate biosecurity and infection control procedures in veterinary practice.