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Clostridioides difficile infection (CDI) remains an urgent global One Health threat. The genetic heterogeneity seen across C. difficile underscores its wide ecological versatility and has driven the significant changes in CDI epidemiology seen in the last 20 years. We analysed an international collection of over 12,000 C. difficile genomes spanning the eight currently defined phylogenetic clades. Through whole-genome average nucleotide identity, and pangenomic and Bayesian analyses, we identified major taxonomic incoherence with clear species boundaries for each of the recently described cryptic clades CI–III. The emergence of these three novel genomospecies predates clades C1–5 by millions of years, rewriting the global population structure of C. difficile specifically and taxonomy of the Peptostreptococcaceae in general. These genomospecies all show unique and highly divergent toxin gene architecture, advancing our understanding of the evolution of C. difficile and close relatives. Beyond the taxonomic ramifications, this work may impact the diagnosis of CDI.

In recent years, community-associated Clostridium difficile infection (CA-CDI) has emerged as a significant health problem, accounting for ∼50% of all CDI cases. We hypothesized that the home garden environment could contribute to the dissemination of C. difficile spores in the community and investigated 23 homes in 22 suburbs of Perth, Western Australia. We identified a high prevalence of toxigenic C. difficile in this environment. In total, 97 samples consisting of soil (n = 48), compost (n = 15), manure (n = 12), and shoe sole swabs (n = 22) were collected. All samples were cultured anaerobically on C. difficile ChromID agar and enriched in brain heart infusion broth, and isolates were characterized by toxin gene PCR and PCR ribotyping. Two-thirds (67%; 95% confidence interval [CI], 57 to 76%) of home garden samples, including 79% (95% CI, 68 to 91%) of soil, 67% (95% CI, 43 to 90%) of compost, 83% (95% CI, 62% to 100%) of manure, and 32% (95% CI, 12 to 51%) of shoe sole samples, contained C. difficile. Of 87 isolates, 38% (95% CI, 28 to 48%) were toxigenic, and 26 PCR ribotypes (RTs), 5 of which were novel, were identified. The toxigenic C. difficile strain RT014/020 was the most prevalent RT. Interestingly, 19 esculin hydrolysis-negative strains giving white colonies were identified on C. difficile ChromID agar, 5 of which were novel toxigenic RTs that produced only toxin A. Clearly, there is the potential for transmission of C. difficile in the community due to the contamination of home gardens. Our findings highlight the importance of a “One Health” approach to dealing with CDI. IMPORTANCE Recently, community-associated Clostridium difficile infection (CA-CDI) has emerged as a significant problem, accounting for ∼50% of all CDI cases and reported to affect a younger population without traditional risk factors. Possible sources of CA-CDI are soil, food, and water contaminated by animal feces, and recent reports show overlapping ribotypes of C. difficile in animals, humans, and the environment; however, the epidemiology of CA-CDI and related risk factors need to be better understood. Our research aimed to determine the prevalence of C. difficile in home gardens and on the shoe soles of homeowners in Perth, Western Australia. There were high rates of contamination with C. difficile in gardens, and some of the ribotypes identified had been isolated from human cases of CDI in Western Australia. This study shows that home gardens and shoes may be a source of C. difficile in CA-CDI.

Background: Clostridium difficile is a common antimicrobial-resistant bacterium in healthcare and community settings. C. difficile colonises the gastrointestinal tract and proliferates as a result of the disruption to microbiota from antimicrobial exposure. Increasing rates of hospital and community-acquired C. difficile infections (CA-CDI) in children have been recorded in many parts of the world, however, research in Australia has been limited. The C. difficile Antimicrobial Resistance Surveillance (CDARS) study is a longitudinal investigation of both the molecular epidemiology and antimicrobial resistance phenotype of C. difficile isolated in Australia since 2013. Here we report the molecular characterization of C. difficile isolated from paediatric patients during this period. Methods & Materials: C. difficile isolates (or PCR positive stool samples) were sent from 10 laboratories (one private and one public laboratory) across five states in Australia. Isolates were characterized by PCR for toxin genes and ribotyping. Results: Of the 1542 isolates recovered throughout the study period (August–September 2013–February–March 2018), 127 (8.2%) were from paediatric patients with ages ranging from

Clostridium difficile has not been studied in detail in Asia, particularly Southeast Asia. We thus performed a prevalence study across four hospitals in Central Java province, Indonesia. Stool samples were collected from patients with diarrhoea and tested by enzyme immunoassay for glutamate dehydrogenase (GDH) and toxin A/B (C DIFF QUIK CHEK COMPLETE, TechLab). Specimens were cultured and molecular typing was performed. In total, 340 samples were tested, of which 70 (20.6%) were GDH positive, with toxin detected in 19 (5.6%). Toxigenic C. difficile was isolated from 37 specimens (10.9%), while a further 36 (10.6%) nontoxigenic isolates were identified. The most common strain was ribotype 017 (24.3% of 74 isolates), followed by nontoxigenic types QX 224 (9.5%), and QX 238 and QX 108 (both 8.1%). The high prevalence of C. difficile highlights a need for ongoing surveillance of C. difficile infection in Indonesia.

Background Exposure to antimicrobials is the major risk factor associated with Clostridium difficile infection (CDI). Paradoxically, treatment of CDI with antimicrobials remains the preferred option. To date, only three studies have investigated the antimicrobial susceptibility of C. difficile from Thailand, two of which were published in the 1990s. This study aimed to investigate the contemporary antibiotic susceptibility of C. difficile isolated from patients in Thailand. Methods A collection of 105 C. difficile isolated from inpatients admitted at Siriraj Hospital in Bangkok in 2015 was tested for their susceptibility to nine antimicrobials via an agar incorporation method. Results All isolates were susceptible to vancomycin, metronidazole, amoxicillin/clavulanate and meropenem. Resistance to clindamycin, erythromycin and moxifloxacin was observed in 73.3%, 35.2% and 21.0% of the isolates, respectively. The in vitro activity of fidaxomicin (MIC50/MIC90 0.06/0.25 mg/L) was superior to first-line therapies vancomycin (MIC50/MIC90 1/2 mg/L) and metronidazole (MIC50/MIC90 0.25/0.25 mg/L). Rifaximin exhibited potent activity against 85.7% of the isolates (MIC ≤0.03 mg/L), and its MIC50 (0.015 mg/L) was the lowest among all antimicrobials tested. The prevalence of multi-drug resistant C. difficile, defined by resistance to ≥3 antimicrobials, was 21.9% (23/105). Conclusions A high level of resistance against multiple classes of antimicrobial was observed, emphasising the need for enhanced antimicrobial stewardship and educational programmes to effectively disseminate information regarding C. difficile awareness and appropriate use of antimicrobials to healthcare workers and the general public.

Bacterial speciation is a fundamental evolutionary process characterized by diverging genotypic and phenotypic properties. However, the selective forces that affect genetic adaptations and how they relate to the biological changes that underpin the formation of a new bacterial species remain poorly understood. Here, we show that the spore-forming, healthcare-associated enteropathogen Clostridium difficile is actively undergoing speciation. Through large-scale genomic analysis of 906 strains, we demonstrate that the ongoing speciation process is linked to positive selection on core genes in the newly forming species that are involved in sporulation and the metabolism of simple dietary sugars. Functional validation shows that the new C. difficile produces spores that are more resistant and have increased sporulation and host colonization capacity when glucose or fructose is available for metabolism. Thus, we report the formation of an emerging C. difficile species, selected for metabolizing simple dietary sugars and producing high levels of resistant spores, that is adapted for healthcare-mediated transmission.

Clostridioides difficile (Clostridium difficile) sequence type 11 (ST11) is well established in production animal populations worldwide and contributes considerably to the global burden of C. difficile infection (CDI) in humans. Increasing evidence of shared ancestry and genetic overlap of PCR ribotype 078 (RT078), the most common ST11 sublineage, between human and animal populations suggests that CDI may be a zoonosis. We performed whole-genome sequencing (WGS) on a collection of 207 ST11 and closely related ST258 isolates of human and veterinary/environmental origin, comprising 16 RTs collected from Australia, Asia, Europe, and North America. Core genome single nucleotide variant (SNV) analysis identified multiple intraspecies and interspecies clonal groups (isolates separated by ≤2 core genome SNVs) in all the major RT sublineages: 078, 126, 127, 033, and 288. Clonal groups comprised isolates spread across different states, countries, and continents, indicative of reciprocal long-range dissemination and possible zoonotic/anthroponotic transmission. Antimicrobial resistance genotypes and phenotypes varied across host species, geographic regions, and RTs and included macrolide/lincosamide resistance (Tn6194 [ermB]), tetracycline resistance (Tn6190 [tetM] and Tn6164 [tet44]), and fluoroquinolone resistance (gyrA/B mutations), as well as numerous aminoglycoside resistance cassettes. The population was defined by a large “open” pan-genome (10,378 genes), a remarkably small core genome of 2,058 genes (only 19.8% of the gene pool), and an accessory genome containing a large and diverse collection of important prophages of the Siphoviridae and Myoviridae. This study provides novel insights into strain relatedness and genetic variability of C. difficile ST11, a lineage of global One Health importance. IMPORTANCE Historically, Clostridioides difficile (Clostridium difficile) has been associated with life-threatening diarrhea in hospitalized patients. Increasing rates of C. difficile infection (CDI) in the community suggest exposure to C. difficile reservoirs outside the hospital, including animals, the environment, or food. C. difficile sequence type 11 (ST11) is known to infect/colonize livestock worldwide and comprises multiple ribotypes, many of which cause disease in humans, suggesting CDI may be a zoonosis. Using high-resolution genomics, we investigated the evolution and zoonotic potential of ST11 and a new closely related ST258 lineage sourced from diverse origins. We found multiple intra- and interspecies clonal transmission events in all ribotype sublineages. Clones were spread across multiple continents, often without any health care association, indicative of zoonotic/anthroponotic long-range dissemination in the community. ST11 possesses a massive pan-genome and numerous clinically important antimicrobial resistance elements and prophages, which likely contribute to the success of this globally disseminated lineage of One Health importance.

Coagulase-negative staphylococci (CoNS), such as Staphylococcus capitis, are major causes of bloodstream infections in neonatal intensive care units (NICUs). Recently, a distinct clone of S. capitis (designated S. capitis NRCS-A) has emerged as an important pathogen in NICUs internationally., Coagulase-negative staphylococci (CoNS), such as Staphylococcus capitis, are major causes of bloodstream infections in neonatal intensive care units (NICUs). Recently, a distinct clone of S. capitis (designated S. capitis NRCS-A) has emerged as an important pathogen in NICUs internationally. Here, 122 S. capitis isolates from New Zealand (NZ) underwent whole-genome sequencing (WGS), and these data were supplemented with publicly available S. capitis sequence reads. Phylogenetic and comparative genomic analyses were performed, as were phenotypic assessments of antimicrobial resistance, biofilm formation, and plasmid segregational stability on representative isolates. A distinct lineage of S. capitis was identified in NZ associated with neonates and the NICU environment. Isolates from this lineage produced increased levels of biofilm, displayed higher levels of tolerance to chlorhexidine, and were multidrug resistant. Although similar to globally circulating NICU-associated S. capitis strains at a core-genome level, NZ NICU S. capitis isolates carried a novel stably maintained multidrug-resistant plasmid that was not present in non-NICU isolates. Neonatal blood culture isolates were indistinguishable from environmental S. capitis isolates found on fomites, such as stethoscopes and neonatal incubators, but were generally distinct from those isolates carried by NICU staff. This work implicates the NICU environment as a potential reservoir for neonatal sepsis caused by S. capitis and highlights the capacity of genomics-based tracking and surveillance to inform future hospital infection control practices aimed at containing the spread of this important neonatal pathogen.

Background Current knowledge of the epidemiology of Clostridium difficile infection in Asia, and in particular the Greater Mekong Subregion, is very limited. Only a few studies from Thailand and Vietnam have been reported from the region with variable testing methods and results, and no studies from Lao People’s Democratic Republic (PDR). Therefore we investigated the presence of C. difficile in a single centre in the Lao PDR and determined the ribotypes present. Method Seventy unformed stool samples from hospital inpatients at Mahosot Hospital, Vientiane, were tested for the presence of C. difficile using selective differential agar and confirmed by latex agglutination. C. difficile isolates were further characterised by ribotyping and toxin gene detection. Results C. difficile was isolated from five of the 70 patients, and five different ribotypes were identified (014, 017, 020, QX 107 and QX 574). Conclusion This is the first isolation of C. difficile from human stool samples in the Lao PDR. These results will add to the limited amount of data on C. difficile in the region. In addition, we hope this information will alert clinicians to the presence of C. difficile in the country and will help inform future investigations into the epidemiology and diagnosis of C. difficile in Lao PDR.

The diarrheal pathogen Clostridium difficile consists of at least six distinct evolutionary lineages. The RT017 lineage is anomalous, as strains only express toxin B, compared to strains from other lineages that produce toxins A and B and, occasionally, binary toxin. Historically, RT017 initially was reported in Asia but now has been reported worldwide. We used whole-genome sequencing and phylogenetic analysis to investigate the patterns of global spread and population structure of 277 RT017 isolates from animal and human origins from six continents, isolated between 1990 and 2013. We reveal two distinct evenly split sublineages (SL1 and SL2) of C. difficile RT017 that contain multiple independent clonal expansions. All 24 animal isolates were contained within SL1 along with human isolates, suggesting potential transmission between animals and humans. Genetic analyses revealed an overrepresentation of antibiotic resistance genes. Phylogeographic analyses show a North American origin for RT017, as has been found for the recently emerged epidemic RT027 lineage. Despite having only one toxin, RT017 strains have evolved in parallel from at least two independent sources and can readily transmit between continents.

Background: Well-known risk factors for Clostridium difficile infection (CDI) are exposure to antibiotics and gastric acid suppressants. Recent studies have provided some evidence of an association between hypovitaminosis D and the risk of CDI. Therefore, this meta-analysis aimed to pool all the existing evidence to investigate the association between 25-hydroxyvitamin D (25[OH]D) and CDI. Methods: A systematic search was conducted in 3 databases (PubMed, Embase, and Web of Sciences) for epidemiological studies that examined the association between mean 25(OH)D concentrations and CDI as well as between 25(OH)D status and CDI severity or recurrence. 25(OH)D status was defined as "lower" or "higher" at a threshold concentration of

The epidemiology of Clostridium difficile infection (CDI) has changed over time and between countries. It is therefore essential to monitor the characteristics of patients at risk of infection and the circulating strains to recognize local and global trends, and improve patient management. From December 2011 to May 2012 we conducted a prospective, observational epidemiological study of patients with laboratory-confirmed CDI at two tertiary teaching hospitals in Perth, Western Australia to determine CDI incidence and risk factors in an Australian setting. The incidence of CDI varied from 5.2 to 8.1 cases/10 000 occupied bed days (OBDs) at one hospital and from 3.9 to 16.3/10 000 OBDs at the second hospital. In total, 80 patients with laboratory-confirmed CDI met eligibility criteria and consented to be in the study. More than half (53.8%) had hospital-onset disease, 28.8% had community-onset and healthcare facility-associated disease and 7.5% were community-associated infections according to the definitions used. Severe CDI was observed in 40.0% of these cases but the 30-day mortality rate for all cases was only 2.5%. Besides a shorter length of stay among cases of community-onset CDI, no characteristics were identified that were significantly associated with community-onset or severe CDI. From 70 isolates, 34 different ribotypes were identified. The predominant ribotypes were 014 (24.3%), 020 (5.7%), 056 (5.7%) and 070 (5.7%). Whereas this study suggests that the characteristics of CDI cases in Australia are not markedly different from those in other developed countries, the increase in CDI rate observed emphasizes the importance of surveillance.

Introduction: Clostridium difficile infection (CDI) is a significant gastrointestinal disease in the developed world and increasingly recognised as a zoonotic infection. In North America and Europe, the PCR ribotype (RT) 078 strain of C. difficile is commonly found in production animals and as a cause of disease in humans although proof of transmission from animals is lacking. This strain is absent in Australian livestock. We report a case of human CDI caused by a strain of C. difficile belonging to known Australian livestock-associated RT 237. Case presentation: A young male was admitted for multiple trauma following a motor vehicle accident and placed on piperacillin/tazobactam for pneumonia. After 4 days of treatment, he developed symptoms of CDI, which was confirmed in the laboratory. His symptoms resolved after 6 days of intravenous metronidazole. The strain of C. difficile isolated was identified as RT 237, an unusual RT previously found in with several Western Australia piggeries. Conclusion: This case of CDI caused by an unusual livestock-associated C. difficile RT 237 supports the hypothesis of zoonotic transmission. The case highlights the potential of livestock to act as reservoir for C. difficile and the need for continued surveillance of CDI in both human and animal populations.

The symptoms of Clostridium difficile infection are caused by toxins expressed from its 19 kb pathogenicity locus (PaLoc). Stable integration of the PaLoc is suggested by its single chromosomal location and the clade specificity of its different genetic variants. However, the PaLoc is variably present, even among closely related strains, and thus resembles a mobile genetic element. Our aim was to explain these apparently conflicting observations by reconstructing the evolutionary history of the PaLoc. Phylogenetic analyses and annotation of the regions spanning the PaLoc were performed using C. difficile population-representative genomes chosen from a collection of 1,693 toxigenic (PaLoc present) and nontoxigenic (PaLoc absent) isolates. Comparison of the core genome and PaLoc phylogenies demonstrated an eventful evolutionary history, with distinct PaLoc variants acquired clade specifically after divergence. In particular, our data suggest a relatively recent PaLoc acquisition in clade 4. Exchanges and losses of the PaLoc DNA have also occurred, via long homologous recombination events involving flanking chromosomal sequences. The most recent loss event occurred ∼30 years ago within a clade 1 genotype. The genetic organization of the clade 3 PaLoc was unique in containing a stably integrated novel transposon (designated Tn6218), variants of which were found at multiple chromosomal locations. Tn6218 elements were Tn916-related but nonconjugative and occasionally contained genes conferring resistance to clinically relevant antibiotics. The evolutionary histories of two contrasting but clinically important genetic elements were thus characterized: the PaLoc, mobilized rarely via homologous recombination, and Tn6218, mobilized frequently through transposition.

To the Editor: In Queensland, Australia, a steady increase in community-acquired (CA) Clostridium difficile infections (CDI) during 2003–2012 could not be explained by patients’ demographic characteristics or environmental factors (1). Several risk factors have been implicated in the increased rates of CA-CDI, primarily exposure to antimicrobial drugs, gastric acid–suppression drugs, and corticosteroids (2). Given the recent rise in prescription of corticosteroids and proton pump inhibitors in Australia, we hypothesized that the observed increase in CA-CDI was associated with increased drug prescriptions.

TOC Summary: Prior episodes increase risk for long-term adverse health effects., To quantify the risk and types of sequelae attributable to prior enteric infections, we undertook a population-based retrospective cohort study using linked administrative records. The risk for first-time hospitalization for sequelae was modeled by using Cox proportional regression analysis controlling for other health and sociodemographic factors. We identified a significant increase of 64% in the rate of first-time hospitalization for sequelae for persons with prior enteric infections: 52% for intragastrointestinal sequelae and 63% for extragastrointestinal sequelae compared with first-time hospitalization for those without prior infection. Extragastrointestinal sequelae occurred predominantly during the first 5 years after first-time enteric infection. In contrast, most intragastrointestinal sequelae occurred >10 years later. Infective gastroenteritis during childhood or adolescence increases the risk for first-time hospitalization for intragastrointestinal and extragastrointestinal disease over the 2 decades after first-time enteric infection, highlighting the importance of identifying ways of reducing the incidence of such infections.

Following rapid, global clonal dominance of hypervirulent ribotypes, Clostridium difficile now constitutes the primary infectious cause of nosocomial diarrhoea. Evidence indicates at least three possible mechanisms of hypervirulence that facilitates the successful invasion of these atypical strains: 1) increased infectiousness relative to endemic strains; 2) increased symptomatic disease rate relative to endemic strains; and 3) an ability to outcompete endemic strains in the host’s gut. Stochastic simulations of an infection transmission model demonstrate clear differences between the invasion potentials of C. difficile strains utilising the alternative hypervirulence mechanisms and provide new evidence that favours certain mechanisms (1 and 2) more than others (3). Additionally, simulations illustrate that direct competition between strains (inside the host’s gut) is not a prerequisite for the sudden switching that has been observed in prevailing ribotypes; previously dominant C. difficile strains can be excluded by hypervirulent ribotypes through indirect (exploitative) competition.

BACKGROUND: Studies have demonstrated seasonal variability in rates of Clostridium difficile infection (CDI). Synthesising all available information on seasonality is a necessary step in identifying large-scale epidemiological patterns and elucidating underlying causes. METHODS: Three medical and life sciences publication databases were searched from inception to October 2014 for longitudinal epidemiological studies written in English, Spanish or Portuguese that reported the incidence of CDI. The monthly frequency of CDI were extracted, standardized and weighted according to the number of follow-up months. Cross correlation coefficients (XCORR) were calculated to examine the correlation and lag between the year-month frequencies of reported CDI across hemispheres and continents. RESULTS: The search identified 13, 5 and 2 studies from North America, Europe, and Oceania, respectively that met the inclusion criteria. CDI had a similar seasonal pattern in the Northern and Southern Hemisphere characterized by a peak in spring and lower frequencies of CDI in summer/autumn with a lag of 8 months (XCORR = 0.60) between hemispheres. There was no difference between the seasonal patterns across European and North American countries. CONCLUSION: CDI demonstrates a distinct seasonal pattern that is consistent across North America, Europe and Oceania. Further studies are required to identify the driving factors of the observed seasonality.

Thirty two new binaphthyl-based, functionalized oxazole and thiazole peptidomimetics and over thirty five novel leucine-containing intermediate oxazoles and thiazoles were prepared in this study. This includes the first examples of the direct C-5 arylation of an amino acid dipeptide-derived oxazole. Moderate to excellent antibacterial activity was observed for all new compounds across Gram positive isolates with MICs ranging from 1-16 μg mL(-1). Results for Gram negative E. coli and A. baumannii were more variable, but MICs as low as 4 μg mL(-1) were returned for two examples. Significantly, the in vitro results with a fluoromethyl-oxazole derivative collectively represent the best obtained to date for a member of our binaphthyl peptide antimicrobials.

Clostridium difficile causes neonatal enteritis in piglets; strains of PCR ribotype 078 are most commonly identified. We investigated C. difficile prevalence in piglets in Australia and isolated a novel strain with a unique pathogenicity locus. In a mouse infection model, this strain produced more weight loss than did a ribotype 078 strain.

Clostridium difficile is the leading cause of infectious diarrhea in hospitalized patients. Integrating several infection control and prevention methods is a burgeoning strategy for reducing disease incidence in healthcare settings. We present an up-to-date review of the literature on 'control bundles' used to mitigate the transmission of this pathogen. All clinical studies of control bundles reported substantial reductions in disease rates, in the order of 33%-61%. Using a biologically realistic mathematical model we then simulated the efficacy of different combinations of the most prominent control methods: stricter antimicrobial stewardship; the administering of probiotics/intestinal microbiota transplantation; and improved hygiene and sanitation. We also assessed the health gains that can be expected from reducing the average length of stay of inpatients. In terms of reducing the rates of colonization, all combinations had the potential to give rise to marked improvements. For example, halving the number of inpatients on broad-spectrum antimicrobials combined with prescribing probiotics or intestinal microbiota transplantation could cut pathogen carriage by two-thirds. However, in terms of symptomatic disease incidence reduction, antimicrobials, probiotics and intestinal microbiota transplantation proved substantially less effective. Eliminating within-ward transmission by improving sanitation and reducing average length of stay (from six to three days) yielded the most potent symptomatic infection control combination, cutting rates down from three to less than one per 1000 hospital bed days. Both the empirical and theoretical exploration of C. difficile control combinations presented in the current study highlights the potential gains that can be achieved through strategically integrated infection control.

Nontypeable Haemophilus influenzae (NTHI) strains are responsible for respiratory-related infections which cause a significant burden of disease in Australian children. We previously identified a disparity in NTHI culture-defined carriage rates between Aboriginal and non-Aboriginal children (42% versus 11%). The aim of this study was to use molecular techniques to accurately determine the true NTHI carriage rates (excluding other culture-identical Haemophilus spp.) and assess whether the NTHI strain diversity correlates with the disparity in NTHI carriage rates. NTHI isolates were cultured from 595 nasopharyngeal aspirates collected longitudinally from asymptomatic Aboriginal ( n = 81) and non-Aboriginal ( n = 76) children aged 0 to 2 years living in the Kalgoorlie-Boulder region, Western Australia. NTHI-specific 16S rRNA gene PCR and PCR ribotyping were conducted on these isolates. Confirmation of NTHI by 16S rRNA gene PCR corrected the NTHI carriage rates from 42% to 36% in Aboriginal children and from 11% to 9% in non-Aboriginal children. A total of 75 different NTHI ribotypes were identified, with 51% unique to Aboriginal children and 13% unique to non-Aboriginal children ( P < 0.0001). The strain richness (proportion of different NTHI ribotypes) was similar for Aboriginal (19%, 65/346) and non-Aboriginal children (19%, 37/192) ( P = 0.909). Persistent carriage of the same ribotype was rare in the two groups, but colonization with multiple NTHI strains was more common in Aboriginal children than in non-Aboriginal children. True NTHI carriage was less than that estimated by culture. The Aboriginal children were more likely to carry unique and multiple NTHI strains, which may contribute to the chronicity of NTHI colonization and subsequent disease.

Typing of Clostridium difficile facilitates understanding of the epidemiology of the infection. Some evaluations have shown that certain strain types (for example, ribotype 027) are more virulent than others and are associated with worse clinical outcomes. Although restriction endonuclease analysis (REA) and pulsed-field gel electrophoresis have been widely used in the past, PCR ribotyping is the current method of choice for typing of C. difficile . However, global standardization of ribotyping results is urgently needed. Whole-genome sequencing of C. difficile has the potential to provide even greater epidemiologic information than ribotyping.

Recent reports in North America and Europe of Clostridium difficile being isolated from livestock and retail meats of bovine origin have raised concerns about the risk to public health. To assess the situation in Australia, we investigated the prevalence and genetic diversity of C. difficile in adult cattle and calves at slaughter. Carcass washings, gastrointestinal contents, and feces were collected from abattoirs across five Australian states. Selective culture, toxin profiling, and PCR ribotyping were performed. The prevalence of C. difficile was 56% (203/360 samples) in feces from

This study examined the effect of subinhibitory Melaleuca alternifolia (tea tree) essential oil on the development of antibiotic resistance in Staphylococcus aureus and Escherichia coli . Frequencies of single-step antibiotic-resistant mutants were determined by inoculating bacteria cultured with or without subinhibitory tea tree oil onto agar containing 2 to 8 times the MIC of each antibiotic and with or without tea tree oil. Whereas most differences in resistance frequencies were relatively minor, the combination of kanamycin and tea tree oil yielded approximately 10-fold fewer resistant E. coli mutants than kanamycin alone. The development of multistep antibiotic resistance in the presence of tea tree oil or terpinen-4-ol was examined by culturing S. aureus and E. coli isolates daily with antibiotic alone, antibiotic with tea tree oil, and antibiotic with terpinen-4-ol for 6 days. Median MICs for each antibiotic alone increased 4- to 16-fold by day 6. Subinhibitory tea tree oil or terpinen-4-ol did not greatly alter results, with day 6 median MICs being either the same as or one concentration different from those for antibiotic alone. For tea tree oil and terpinen-4-ol alone, day 6 median MICs had increased 4-fold for S. aureus ( n = 18) and 2-fold for E. coli ( n = 18) from baseline values. Lastly, few significant changes in antimicrobial susceptibility were seen for S. aureus and S. epidermidis isolates that had been serially subcultured 14 to 22 times with subinhibitory terpinen-4-ol. Overall, these data indicate that tea tree oil and terpinen-4-ol have little impact on the development of antimicrobial resistance and susceptibility.

Stenotrophomonas maltophilia is an opportunistic pathogen that occupies a variety of niches both inside and outside hospitals, mostly in moist environments ([1][1]). Whitby et al. recently developed species-specific PCR (SS-PCR) primers directed at a region of the S. maltophilia 23S rRNA gene to