Pantoea agglomerans: A rare infectious outbreak affecting maintenance hemodialysis patients in a tertiary care hospital.

BACKGROUND: Pantoea agglomerans is an environmental pathogen known to cause infection in immunocompromised individuals, particularly after thorn injuries. However, previous data showed few cases of human disease caused by contaminated medical products such as parenteral nutrition, anesthetic agents, blood, and peritoneal dialysis solutions. Infection in hemodialysis patients is rare. In this study, we presented a detailed account of several hemodialysis patients infected with this contagious pathogen and compared them with noninfected dialysis patients. METHODS: We retrospectively reviewed the hospital records of 105 hemodialysis patients. Seventeen of 105 patients were diagnosed with P. agglomerans infection. We carefully analyzed their entire in-hospital course. RESULTS: Among infected patients, 52.9% were male with a median age of 49 (IQR: 32-66) years. Compared to the noninfected patients, age below 50 years, prior kidney transplantation, prior immunosuppression and antibiotics use, and dialysis via a tunneled vascular catheter were the significant epidemiological features. Despite negative microbiological investigations, we suspect the possible infectious spread via infected central venous catheter was the likely infectious source. Most importantly, all patients responded well to intravenous antibiotics. Only two patients required the removal of the tunneled catheter. Their mortality rate was 0%. CONCLUSION: P. agglomerans infection, although considered rare, is becoming increasingly prevalent among dialysis patients. Its occurrence must be appraised as an infectious outbreak rather than mere contamination. Prompt treatment, source identification, and early implementation of preventive strategies should always be the goal to curtail this infection at an early stage.

Integrating sample similarities into latent class analysis: a tree-structured shrinkage approach.

This paper is concerned with using multivariate binary observations to estimate the probabilities of unobserved classes with scientific meanings. We focus on the setting where additional information about sample similarities is available and represented by a rooted weighted tree. Every leaf in the given tree contains multiple samples. Shorter distances over the tree between the leaves indicate a priori higher similarity in class probability vectors. We propose a novel data integrative extension to classical latent class models with tree-structured shrinkage. The proposed approach enables (1) borrowing of information across leaves, (2) estimating data-driven leaf groups with distinct vectors of class probabilities, and (3) individual-level probabilistic class assignment given the observed multivariate binary measurements. We derive and implement a scalable posterior inference algorithm in a variational Bayes framework. Extensive simulations show more accurate estimation of class probabilities than alternatives that suboptimally use the additional sample similarity information. A zoonotic infectious disease application is used to illustrate the proposed approach. The paper concludes by a brief discussion on model limitations and extensions.

Plugging the leaks: antibiotic resistance at human-animal interfaces in low-resource settings.

Antibiotic resistance is one of the greatest public health challenges of our time. International efforts to curb resistance have largely focused on drug development and limiting unnecessary antibiotic use. However, in areas where water, sanitation, and hygiene infrastructure is lacking, we propose that bacterial flow between humans and animals can exacerbate the emergence and spread of resistant pathogens. Here, we describe the consequences of poor environmental controls by comparing mobile resistance elements among Escherichia coli recovered from humans and meat in Cambodia, a middle-income country with substantial human-animal connectivity and unregulated antibiotic use. We identified identical mobile resistance elements and a conserved transposon region that were widely dispersed in both humans and animals, a phenomenon rarely observed in high-income settings. Our findings indicate that plugging leaks at human-animal interfaces should be a critical part of addressing antibiotic resistance in low- and especially middle-income countries.

Transmission of Antimicrobial-Resistant Staphylococcus aureus Clonal Complex 9 between Pigs and Humans, United States.

Transmission of livestock-associated Staphylococcus aureus clonal complex 9 (LA-SA CC9) between pigs raised on industrial hog operations (IHOs) and humans in the United States is poorly understood. We analyzed whole-genome sequences from 32 international S. aureus CC9 isolates and 49 LA-SA CC9 isolates from IHO pigs and humans who work on or live near IHOs in 10 pig-producing counties in North Carolina, USA. Bioinformatic analysis of sequence data from the 81 isolates demonstrated 3 major LA-SA CC9 clades. North Carolina isolates all fell within a single clade (C3). High-resolution phylogenetic analysis of C3 revealed 2 subclades of intermingled IHO pig and human isolates differing by 0-34 single-nucleotide polymorphisms. Our findings suggest that LA-SA CC9 from pigs and humans share a common source and provide evidence of transmission of antimicrobial-resistant LA-SA CC9 between IHO pigs and humans who work on or live near IHOs in North Carolina.

mcr-Positive Escherichia coli ST131-H22 from Poultry in Brazil.

Escherichia coli sequence type (ST) 131 is of concern because it can acquire antimicrobial resistance and cause extraintestinal infections. E. coli ST131-H22 sublineage appears capable of being transmitted to humans through poultry. We report on multidrug-resistant ST131-H22 poultry isolates in Brazil closely related to international human and poultry isolates.

Accessory Traits and Phylogenetic Background Predict Escherichia coli Extraintestinal Virulence Better Than Does Ecological Source.

Background: The distinguishing characteristics of extraintestinal pathogenic Escherichia coli (ExPEC) strains are incompletely defined. Methods: We characterized 292 diverse-source human Escherichia coli isolates (116 from fecal specimens, 79 from urine specimens [of which 39 were from patients with cystitis and 40 were from patients with pyelonephritis], and 97 from blood specimens) for phylogenetic group, sequence type complex (STc), and 49 putative extraintestinal pathogenic E. coli (ExPEC)-associated virulence genes. We then assessed these traits and ecological source as predictors of illness severity in a murine sepsis model. Results: The study isolates exhibited a broad range of virulence in mice. Most of the studied bacterial characteristics corresponded significantly with experimental virulence, as did ecological source and established molecular definitions of ExPEC and uropathogenic E. coli (UPEC). Multivariable modeling identified the following bacterial traits as independent predictors of illness severity both overall and among the fecal and clinical (ie, urine and blood) isolates separately: fyuA (yersiniabactin receptor), kpsM K1 (K1 capsule), and kpsM II (group 2 capsules). Molecular UPEC status predicted virulence independently only among fecal isolates. Neither ecological source (ie, clinical vs fecal) nor molecular ExPEC status added predictive power to these traits, which accounted collectively for up to 49% of the observed variation in virulence. Conclusions: Among human-source E. coli isolates, specific accessory traits and phylogenetic/clonal backgrounds predict experimental virulence in a murine sepsis model better than does ecological source.

Inactivation of Transcriptional Regulators during Within-Household Evolution of Escherichia coli.

We analyzed the within-household evolution of two household-associated Escherichia coli strains from pandemic clonal group ST131-H30, using isolates recovered from five individuals within two families, each of which had a distinct strain. Family 1's strain was represented by a urine isolate from the index patient (older sister) with recurrent cystitis and a blood isolate from her younger sister with fatal urosepsis. Family 2's strain was represented by a urine isolate from the index patient (father) with pyelonephritis and renal abscesses, blood and kidney drainage isolates from the daughter with emphysematous pyelonephritis, and urine and fecal isolates from the mother with cystitis. Collectively, the several variants of each family's strain had accumulated a total of 8 (family 1) and 39 (family 2) point mutations; no two isolates were identical. Of the 47 total mutations, 36 resulted in amino acid changes or truncation of coded proteins. Fourteen such mutations (39%) targeted genes encoding transcriptional regulators, and 9 (25%) involved DNA-binding transcription factors (TFs), which significantly exceeded the relative contribution of TF genes to the isolates' genomes (∼6%). At least one-half of the transcriptional regulator mutations were inactivating, based on phenotypic and/or transcriptional analysis. In particular, inactivating mutations in the global regulator LrhA (repressor of type 1 fimbriae and flagella) occurred in the blood isolates from both households and increased the virulence of E. coli strains in a murine sepsis model. The results indicate that E. coli undergoes adaptive evolution between and/or within hosts, generating subpopulations with distinctive phenotypes and virulence potential.IMPORTANCE The clonal evolution of bacterial strains associated with interhost transmission is poorly understood. We characterized the genome sequences of clonal descendants of two Escherichia coli strains, recovered at different time points from multiple individuals within two households who had different types of urinary tract infection. We found evidence that the E. coli strains underwent extensive mutational diversification between and within these individuals, driven disproportionately by inactivation of transcriptional regulators. In urosepsis isolates, the mutations observed in the global regulator LrhA increased bacterial virulence in a murine sepsis model. Our findings help in understanding the adaptive dynamics and strategies of E. coli during short-term natural evolution.

The semen microbiome and its relationship with local immunology and viral load in HIV infection.

Semen is a major vector for HIV transmission, but the semen HIV RNA viral load (VL) only correlates moderately with the blood VL. Viral shedding can be enhanced by genital infections and associated inflammation, but it can also occur in the absence of classical pathogens. Thus, we hypothesized that a dysregulated semen microbiome correlates with local HIV shedding. We analyzed semen samples from 49 men who have sex with men (MSM), including 22 HIV-uninfected and 27 HIV-infected men, at baseline and after starting antiretroviral therapy (ART) using 16S rRNA gene-based pyrosequencing and quantitative PCR. We studied the relationship of semen bacteria with HIV infection, semen cytokine levels, and semen VL by linear regression, non-metric multidimensional scaling, and goodness-of-fit test. Streptococcus, Corynebacterium, and Staphylococcus were common semen bacteria, irrespective of HIV status. While Ureaplasma was the more abundant Mollicutes in HIV-uninfected men, Mycoplasma dominated after HIV infection. HIV infection was associated with decreased semen microbiome diversity and richness, which were restored after six months of ART. In HIV-infected men, semen bacterial load correlated with seven pro-inflammatory semen cytokines, including IL-6 (p = 0.024), TNF-α (p = 0.009), and IL-1b (p = 0.002). IL-1b in particular was associated with semen VL (r(2)  = 0.18, p = 0.02). Semen bacterial load was also directly linked to the semen HIV VL (r(2) = 0.15, p = 0.02). HIV infection reshapes the relationship between semen bacteria and pro-inflammatory cytokines, and both are linked to semen VL, which supports a role of the semen microbiome in HIV sexual transmission.

Intermingled Klebsiella pneumoniae Populations Between Retail Meats and Human Urinary Tract Infections.

BACKGROUND: Klebsiella pneumoniae is a common colonizer of the gastrointestinal tract of humans, companion animals, and livestock. To better understand potential contributions of foodborne K. pneumoniae to human clinical infections, we compared K. pneumoniae isolates from retail meat products and human clinical specimens to assess their similarity based on antibiotic resistance, genetic relatedness, and virulence. METHODS: Klebsiella pneumoniae was isolated from retail meats from Flagstaff grocery stores in 2012 and from urine and blood specimens from Flagstaff Medical Center in 2011-2012. Isolates underwent antibiotic susceptibility testing and whole-genome sequencing. Genetic relatedness of the isolates was assessed using multilocus sequence typing and phylogenetic analyses. Extraintestinal virulence of several closely related meat-source and urine isolates was assessed using a murine sepsis model. RESULTS: Meat-source isolates were significantly more likely to be multidrug resistant and resistant to tetracycline and gentamicin than clinical isolates. Four sequence types occurred among both meat-source and clinical isolates. Phylogenetic analyses confirmed close relationships among meat-source and clinical isolates. Isolates from both sources showed similar virulence in the mouse sepsis model. CONCLUSIONS: Meat-source K. pneumoniae isolates were more likely than clinical isolates to be antibiotic resistant, which could reflect selective pressures from antibiotic use in food-animal production. The close genetic relatedness of meat-source and clinical isolates, coupled with similarities in virulence, suggest that the barriers to transmission between these 2 sources are low. Taken together, our results suggest that retail meat is a potential vehicle for transmitting virulent, antibiotic-resistant K. pneumoniae from food animals to humans.

Clonal Dissemination of Enterobacter cloacae Harboring blaKPC-3 in the Upper Midwestern United States.

Carbapenemase-producing, carbapenem-resistant Enterobacteriaceae, or CP-CRE, are an emerging threat to human and animal health, because they are resistant to many of the last-line antimicrobials available for disease treatment. Carbapenemase-producing Enterobacter cloacae harboring blaKPC-3 recently was reported in the upper midwestern United States and implicated in a hospital outbreak in Fargo, North Dakota (L. M. Kiedrowski, D. M. Guerrero, F. Perez, R. A. Viau, L. J. Rojas, M. F. Mojica, S. D. Rudin, A. M. Hujer, S. H. Marshall, and R. A. Bonomo, Emerg Infect Dis 20:1583-1585, 2014, http://dx.doi.org/10.3201/eid2009.140344). In early 2009, the Minnesota Department of Health began collecting and screening CP-CRE from patients throughout Minnesota. Here, we analyzed a retrospective group of CP-E. cloacae isolates (n = 34) collected between 2009 and 2013. Whole-genome sequencing and analysis revealed that 32 of the strains were clonal, belonging to the ST171 clonal complex and differing collectively by 211 single-nucleotide polymorphisms, and it revealed a dynamic clone under positive selection. The phylogeography of these strains suggests that this clone existed in eastern North Dakota and western Minnesota prior to 2009 and subsequently was identified in the Minneapolis and St. Paul metropolitan area. All strains harbored identical IncFIA-like plasmids conferring a CP-CRE phenotype and an additional IncX3 plasmid. In a single patient with multiple isolates submitted over several months, we found evidence that these plasmids had transferred from the E. cloacae clone to an Escherichia coli ST131 bacterium, rendering it as a CP-CRE. The spread of this clone throughout the upper midwestern United States is unprecedented for E. cloacae and highlights the importance of continued surveillance to identify such threats to human health.

A case control study of environmental and occupational exposures associated with methicillin resistant Staphylococcus aureus nasal carriage in patients admitted to a rural tertiary care hospital in a high density swine region.

BACKGROUND: Distinct strains of methicillin resistant Staphylococcus aureus (MRSA) have been identified on livestock and livestock workers. Industrial food animal production may be an important environmental reservoir for human carriage of these pathogenic bacteria. The objective of this study was to investigate environmental and occupational exposures associated with nasal carriage of MRSA in patients hospitalized at Vidant Medical Center, a tertiary hospital serving a region with intensive livestock production in eastern North Carolina. METHODS: MRSA nasal carriage was identified via nasal swabs collected within 24 hours of hospital admission. MRSA carriers (cases) were gender and age matched to non-carriers (controls). Participants were interviewed about recent environmental and occupational exposures. Home addresses were geocoded and publicly available data were used to estimate the density of swine in residential census block groups of residence. Conditional logistic regression models were used to derive odds ratio (OR) estimates and 95% confidence intervals (CI). Presence of the scn gene in MRSA isolates was assessed. In addition, multi locus sequence typing (MLST) of the MRSA isolates was performed, and the Diversilab® system was used to match the isolates to USA pulsed field gel electrophoresis types. RESULTS: From July - December 2011, 117 cases and 119 controls were enrolled. A higher proportion of controls than cases were current workforce members (41.2% vs. 31.6%) Cases had a higher odds of living in census block groups with medium densities of swine (OR: 4.76, 95% CI: 1.36-16.69) and of reporting the ability to smell odor from a farm with animals when they were home (OR: 1.51, 95% CI: 0.80-2.86). Of 49 culture positive MRSA isolates, all were scn positive. Twenty-two isolates belonged to clonal complex 5. CONCLUSIONS: Absence of livestock workers in this study precluded evaluation of occupational exposures. Higher odds of MRSA in medium swine density areas could reflect environmental exposure to swine or poultry.

Abrupt emergence of a single dominant multidrug-resistant strain of Escherichia coli.

BACKGROUND: Fluoroquinolone-resistant Escherichia coli are increasingly prevalent. Their clonal origins--potentially critical for control efforts--remain undefined. METHODS: Antimicrobial resistance profiles and fine clonal structure were determined for 236 diverse-source historical (1967-2009) E. coli isolates representing sequence type ST131 and 853 recent (2010-2011) consecutive E. coli isolates from 5 clinical laboratories in Seattle, Washington, and Minneapolis, Minnesota. Clonal structure was resolved based on fimH sequence (fimbrial adhesin gene: H subclone assignments), multilocus sequence typing, gyrA and parC sequence (fluoroquinolone resistance-determining loci), and pulsed-field gel electrophoresis. RESULTS: Of the recent fluoroquinolone-resistant clinical isolates, 52% represented a single ST131 subclonal lineage, H30, which expanded abruptly after 2000. This subclone had a unique and conserved gyrA/parC allele combination, supporting its tight clonality. Unlike other ST131 subclones, H30 was significantly associated with fluoroquinolone resistance and was the most prevalent subclone among current E. coli clinical isolates, overall (10.4%) and within every resistance category (11%-52%). CONCLUSIONS: Most current fluoroquinolone-resistant E. coli clinical isolates, and the largest share of multidrug-resistant isolates, represent a highly clonal subgroup that likely originated from a single rapidly expanded and disseminated ST131 strain. Focused attention to this strain will be required to control the fluoroquinolone and multidrug-resistant E. coli epidemic.

To evaluate the utility of Oxford classification in predicting renal outcome in IgA nephropathy patients.

BACKGROUND: Immunoglobulin A Nephropathy (IgAN) is a heterogeneous disorder. Multiple ethnicities conducted studies to assess the effectiveness of the Oxford classification of IgAN in prognostication. However, there is no study on the Pakistani population. We aim to identify its prognostic effectivity in our patients. METHODS: We retrospectively reviewed the medical records of 93 biopsy-proven cases of primary IgAN. We collected the clinical and pathological data at baseline and on follow-ups. The median follow-up period was 12 months. We defined the renal outcome as a ≥ 50% decline in eGFR or end-stage renal disease (ESRD). RESULTS: Of 93 cases, 67.7% were males with a median age of 29. Glomerulosclerosis was the most prevalent lesion (71%). The median MEST-C was 3. On follow-up, median serum creatinine worsened from 1.92 to 2.2 mg/dL, and median proteinuria reduced from 2.3 g/g to 1.072 g/g. The reported renal outcome was 29%. T and C scores and MEST-C scores above 2 were significantly associated with pre-biopsy eGFR. On Kaplan-Meier analysis, the T and C scores' association was significant with the renal outcome (p-value 0.000 and 0.002). In univariate and multivariate analyses, the association of T-score (p-value 0.000, HR 4.691), total MEST-C score (p-value 0.019), and baseline serum creatinine (p-value 0.036, HR 1.188) were significant with the outcome. CONCLUSION: We validate the prognostic significance of the Oxford classification. T and C scores, baseline serum creatinine, and total MEST-C score significantly affect the renal outcome. Furthermore, we recommend the inclusion of the total MEST-C score in determining the IgAN prognosis.

Gut microbiome predictors of Escherichia coli sequence type 131 colonization and loss.

BACKGROUND: Escherichia coli sequence type 131 (ST131), specifically its fluoroquinolone-resistant H30R clade (ST131-H30R), is a global multidrug-resistant pathogen. The gut microbiome's role in ST131-H30R intestinal carriage is undefined. METHODS: Veterans and their household members underwent longitudinal fecal swab surveillance for ST131 in 2014-2018. The fecal microbiome was characterized by 16S rRNA qPCR and sequencing. We evaluated associations between ST131-H30R carriage and gut microbiome at baseline by random forest models to identify the most informative gut bacterial phyla and genera attributes for ST131 and ST131-H30R carriage status. Next, we assessed longitudinal associations between fecal microbiome and ST131-H30R carriage using a mixed-effects logistic regression with longitudinal measures. FINDINGS: Of the 519 participants, 78 were carriers of ST131, among whom 49 had ST131-H30R. At the baseline timepoint, H30R-positive participants had higher proportional abundances of Actinobacteria phylum (mean: 4.9% vs. 3.1%) than ST131-negative participants. H30R-positive participants also had higher abundances of Collinsella (mean: 2.3% vs. 1.1%) and lower abundances of Alistipes (mean: 2.1% vs. 2.6%) than ST131-negative participants. In the longitudinal analysis, Collinsella abundance correlated positively with ST131-H30R carriage status and negatively with the loss of ST131-H30R. Conversely, Alistipes corresponded with the loss and persistent absence of ST131-H30R even in the presence of a household exposure. INTERPRETATION: Abundances of specific fecal bacteria correlated with ST131-H30R carriage, persistence, and loss, suggesting their potential as targets for microbiome-based strategies to reduce carriage of ST131-H30R, a significant risk factor for invasive infections. FUNDING: This work was supported in part by National Institute of Allergy and Infectious Diseases of the National Institutes of Health under award numbers R21AI117654 and UM1AI104681 and the Office of Research and Development, Department of Veterans Affairs. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health or the Department of Veterans Affairs.

Insertive vaginal sex is associated with altered penile immunology and enrichment of Gardnerella vaginalis in uncircumcised Ugandan men.

PROBLEM: HIV susceptibility is linked to the penile immune milieu (particularly IL-8 levels) and microbiome. The effects of insertive vaginal sex itself on penile immunology and microbiota are not well described. METHOD OF STUDY: We compared the immune milieu and microbiology of the coronal sulcus (CS) and distal urethra in 47 uncircumcised Ugandan men reporting ever (n = 42) or never (n = 5) having had vaginal intercourse. Soluble immune factors were assayed by multiplex ELISA, and penile bacteria abundance by 16S rRNA qPCR and sequencing. Co-primary endpoints were penile levels of IL-8 and soluble E-cadherin. RESULTS: Independent of classical STIs, men reporting prior vaginal sex demonstrated elevated IL-8 levels in both the coronal sulcus (1.78 vs. 0.81 log10 pg/mL, p = .021) and urethra (2.93 vs. 2.30 log10 pg/mL; p = .003), with a strong inverse relationship between urethral IL-8 levels and the time from last vaginal sex (r = -0.436; p = .004). Vaginal sex was also associated with elevated penile IL-1α/ß and soluble E-cadherin (sEcad), a marker of epithelial disruption. Gardnerella vaginalis (Gv) was only present in the penile microbiome of men reporting prior vaginal sex, and urethral Gv absolute abundance was strongly associated with urethral inflammation (r = 0.556; p < .001); corynebacteria were enriched in the CS of men reporting no prior vaginal sex and were associated with reduced CS inflammation. CONCLUSIONS: Sexual intercourse was associated with sustained changes in penile immunology, potentially mediated through microbial alterations, in particular the urethral abundance of G. vaginalis. Future studies should further characterize the effects of sexual debut on penile bacteria and immunology.

Comparison of the penile microbiome in infant male circumcision: Mogen clamp versus Shangring.

BACKGROUND: This study aimed to characterise the infant penile (coronal sulcus) microbiome and the effects of early infant male circumcision (EIMC), following a standard surgical method (Mogen Clamp) and a non-surgical alternative (ShangRing). METHODS: We collected coronal sulcus swabs at baseline and on days 7 and 14 post-circumcision from infants assigned to receive EIMC by Mogen Clamp (n = 15) or ShangRing (n = 15), in a randomised trial in Rakai and Kakuuto, Uganda. We used 16S rRNA gene-based sequencing and broad-coverage qPCR to characterise the infant penile microbiome and assess the effects of EIMC in both study arms. FINDINGS: Prior to EIMC, the infant penile microbiome had a mixture of facultative and strict anaerobes. In both study arms, EIMC caused penile microbiome proportional abundance changes characterised by decreases in penile anaerobes [ShangRing Prevotella: -15.0%, (SD = 19.1); Mogen clamp Prevotella: -3.6% (11.2); ShangRing Veillonella: -11.3% (17.2); Mogen clamp Veillonella: -2.6% (11.8)] and increases in skin-associated facultative anaerobes [ShangRing Corynebacterium: 24.9%, (22.4); Mogen clamp Corynebacterium: 4.7% (21.3); ShangRing Staphylococcus: 21.1% (20.5); Mogen clamp Staphylococcus: 18.1% (20.1)]. Clostridium tetani was not detected during the study. INTERPRETATION: Mogen Clamp and ShangRing EIMC both changed the composition of the infant penile microbiome by reducing the proportional abundances of anaerobes and uropathogens, which is consistent with medical male circumcision findings in adults. C. tetani was not increased by either EIMC method. FUNDING: Bill and Melinda Gates Foundation.

Pediatric urinary tract infections caused by poultry-associated Escherichia coli.

Escherichia coli is the leading cause of urinary tract infections (UTIs) in children and adults. The gastrointestinal tract is the primary reservoir of uropathogenic E. coli, which can be acquired from a variety of environmental exposures, including retail meat. In the current study, we used a novel statistical-genomic approach to estimate the proportion of pediatric UTIs caused by foodborne zoonotic E. coli strains. E. coli urine isolates were collected from DC residents aged 2 months to 17 years from the Children's National Medical Center Laboratory, 2013-2014. During the same period, E. coli isolates were collected from retail poultry products purchased from 15 sites throughout DC. A total of 52 urine and 56 poultry isolates underwent whole-genome sequencing, core genome phylogenetic analysis, and host-origin prediction by a Bayesian latent class model that incorporated data on the presence of mobile genetic elements (MGEs) among E. coli isolates from multiple vertebrate hosts. A total of 56 multilocus sequence types were identified among the isolates. Five sequence types-ST10, ST38, ST69, ST117, and ST131-were observed among both urine and poultry isolates. Using the Bayesian latent class model, we estimated that 19% (10/52) of the clinical E. coli isolates in our population were foodborne zoonotic strains. These data suggest that a substantial portion of pediatric UTIs in the Washington DC region may be caused by E. coli strains originating in food animals and likely transmitted via contaminated poultry meat.IMPORTANCEEscherichia coli UTIs are a heavy public health burden and can have long-term negative health consequences for pediatric patients. E. coli has an extremely broad host range, including humans, chickens, turkeys, pigs, and cattle. E. coli derived from food animals is a frequent contaminant of retail meat products, but little is known about the risk these strains pose to pediatric populations. Quantifying the proportion of pediatric UTIs caused by food-animal-derived E. coli, characterizing the highest-risk strains, and identifying their primary reservoir species could inform novel intervention strategies to reduce UTI burden in this vulnerable population. Our results suggest that retail poultry meat may be an important vehicle for pediatric exposure to zoonotic E. coli strains capable of causing UTIs. Vaccinating poultry against the highest-risk strains could potentially reduce poultry colonization, poultry meat contamination, and downstream pediatric infections.

Design and validation of Dolosigranulum pigrum specific PCR primers using the bacterial core genome.

Dolosigranulum pigrum-a lactic acid bacterium that is increasingly recognized as an important member of the nasal microbiome. Currently, there are limited rapid and low-cost options for confirming D. pigrum isolates and detecting D. pigrum in clinical specimens. Here we describe the design and validation of a novel PCR assay targeting D. pigrum that is both sensitive and specific. We designed a PCR assay targeting murJ, a single-copy core species gene identified through the analysis of 21 D. pigrum whole genome sequences. The assay achieved 100% sensitivity and 100% specificity against D. pigrum and diverse bacterial isolates and an overall 91.1% sensitivity and 100% specificity using nasal swabs, detecting D. pigrum at a threshold of 1.0 × 104 D. pigrum 16S rRNA gene copies per swab. This assay adds a reliable and rapid D. pigrum detection tool to the microbiome researcher toolkit investigating the role of generalist and specialist bacteria in the nasal environment.

Using source-associated mobile genetic elements to identify zoonotic extraintestinal E. coli infections.

A one-health perspective may provide new and actionable information about Escherichia coli transmission. E. coli colonizes a broad range of vertebrates, including humans and food-production animals, and is a leading cause of bladder, kidney, and bloodstream infections in humans. Substantial evidence supports foodborne transmission of pathogenic E. coli strains from food animals to humans. However, the relative contribution of foodborne zoonotic E. coli (FZEC) to the human extraintestinal disease burden and the distinguishing characteristics of such strains remain undefined. Using a comparative genomic analysis of a large collection of contemporaneous, geographically-matched clinical and meat-source E. coli isolates (n = 3111), we identified 17 source-associated mobile genetic elements - predominantly plasmids and bacteriophages - and integrated them into a novel Bayesian latent class model to predict the origins of clinical E. coli isolates. We estimated that approximately 8 % of human extraintestinal E. coli infections (mostly urinary tract infections) in our study population were caused by FZEC. FZEC strains were equally likely to cause symptomatic disease as non-FZEC strains. Two FZEC lineages, ST131-H22 and ST58, appeared to have particularly high virulence potential. Our findings imply that FZEC strains collectively cause more urinary tract infections than does any single non-E. coli uropathogenic species (e.g., Klebsiella pneumoniae). Our novel approach can be applied in other settings to identify the highest-risk FZEC strains, determine their sources, and inform new one-health strategies to decrease the heavy public health burden imposed by extraintestinal E. coli infections.

BactQuant: an enhanced broad-coverage bacterial quantitative real-time PCR assay.

BACKGROUND: Bacterial load quantification is a critical component of bacterial community analysis, but a culture-independent method capable of detecting and quantifying diverse bacteria is needed. Based on our analysis of a diverse collection of 16 S rRNA gene sequences, we designed a broad-coverage quantitative real-time PCR (qPCR) assay--BactQuant--for quantifying 16 S rRNA gene copy number and estimating bacterial load. We further utilized in silico evaluation to complement laboratory-based qPCR characterization to validate BactQuant. METHODS: The aligned core set of 4,938 16 S rRNA gene sequences in the Greengenes database were analyzed for assay design. Cloned plasmid standards were generated and quantified using a qPCR-based approach. Coverage analysis was performed computationally using >670,000 sequences and further evaluated following the Minimum Information for Publication of Quantitative Real-Time PCR Experiments (MIQE) guidelines. RESULTS: A bacterial TaqMan® qPCR assay targeting a 466 bp region in V3-V4 was designed. Coverage analysis showed that 91% of the phyla, 96% of the genera, and >80% of the 89,537 species analyzed contained at least one perfect sequence match to the BactQuant assay. Of the 106 bacterial species evaluated, amplification efficiencies ranged from 81 to 120%, with r2-value of >0.99, including species with sequence mismatches. Inter- and intra-run coefficient of variance was <3% and <16% for Ct and copy number, respectively. CONCLUSIONS: The BactQuant assay offers significantly broader coverage than a previously reported universal bacterial quantification assay BactQuant in vitro performance was better than the in silico predictions.