A host receptor enables type 1 pilus-mediated pathogenesis of Escherichia coli pyelonephritis.

Type 1 pili have long been considered the major virulence factor enabling colonization of the urinary bladder by uropathogenic Escherichia coli (UPEC). The molecular pathogenesis of pyelonephritis is less well characterized, due to previous limitations in preclinical modeling of kidney infection. Here, we demonstrate in a recently developed mouse model that beyond bladder infection, type 1 pili also are critical for establishment of ascending pyelonephritis. Bacterial mutants lacking the type 1 pilus adhesin (FimH) were unable to establish kidney infection in male C3H/HeN mice. We developed an in vitro model of FimH-dependent UPEC binding to renal collecting duct cells, and performed a CRISPR screen in these cells, identifying desmoglein-2 as a primary renal epithelial receptor for FimH. The mannosylated extracellular domain of human DSG2 bound directly to the lectin domain of FimH in vitro, and introduction of a mutation in the FimH mannose-binding pocket abolished binding to DSG2. In infected C3H/HeN mice, type 1-piliated UPEC and Dsg2 were co-localized within collecting ducts, and administration of mannoside FIM1033, a potent small-molecule inhibitor of FimH, significantly attenuated bacterial loads in pyelonephritis. Our results broaden the biological importance of FimH, specify the first renal FimH receptor, and indicate that FimH-targeted therapeutics will also have application in pyelonephritis.

Spontaneous Bacterial Peritonitis Caused by Bordetella hinzii.

Although Bordetella hinzii coccobacilli is most commonly identified in respiratory tracts of birds and rodents, this organism has occasionally been isolated in human infections. We describe a case of B. hinzii spontaneous bacterial peritonitis in Missouri, USA. Whole-genome sequencing of blood and peritoneal fluid isolates confirmed B. hinzii infection.

Gata4 potentiates second heart field proliferation and Hedgehog signaling for cardiac septation.

GATA4, an essential cardiogenic transcription factor, provides a model for dominant transcription factor mutations in human disease. Dominant GATA4 mutations cause congenital heart disease (CHD), specifically atrial and atrioventricular septal defects (ASDs and AVSDs). We found that second heart field (SHF)-specific Gata4 heterozygote embryos recapitulated the AVSDs observed in germline Gata4 heterozygote embryos. A proliferation defect of SHF atrial septum progenitors and hypoplasia of the dorsal mesenchymal protrusion, rather than anlage of the atrioventricular septum, were observed in this model. Knockdown of the cell-cycle repressor phosphatase and tensin homolog (Pten) restored cell-cycle progression and rescued the AVSDs. Gata4 mutants also demonstrated Hedgehog (Hh) signaling defects. Gata4 acts directly upstream of Hh components: Gata4 activated a cis-regulatory element at Gli1 in vitro and occupied the element in vivo. Remarkably, SHF-specific constitutive Hh signaling activation rescued AVSDs in Gata4 SHF-specific heterozygous knockout embryos. Pten expression was unchanged in Smoothened mutants, and Hh pathway genes were unchanged in Pten mutants, suggesting pathway independence. Thus, both the cell-cycle and Hh-signaling defects caused by dominant Gata4 mutations were required for CHD pathogenesis, suggesting a combinatorial model of disease causation by transcription factor haploinsufficiency.

Androgen exposure potentiates formation of intratubular communities and renal abscesses by Escherichia coli.

Females across their lifespan and certain male populations are susceptible to urinary tract infections (UTI). The influence of female vs. male sex on UTI is incompletely understood, in part because preclinical modeling has been performed almost exclusively in female mice. Here, we employed established and new mouse models of UTI with uropathogenic Escherichia coli (UPEC) to investigate androgen influence on UTI pathogenesis. Susceptibility to UPEC UTI in both male and female hosts was potentiated with 5α-dihydrotestosterone, while males with androgen receptor deficiency and androgenized females treated with the androgen receptor antagonist enzalutamide were protected from severe pyelonephritis. In androgenized females and in males, UPEC formed dense intratubular, biofilm-like communities, some of which were sheltered from infiltrating leukocytes by the tubular epithelium and by peritubular fibrosis. Abscesses were nucleated by small intratubular collections of UPEC first visualized at five days postinfection and briskly expanded over the subsequent 24 hours. Male mice deficient in Toll-like receptor 4, which fail to contain UPEC within abscesses, were susceptible to lethal dissemination. Thus, androgen receptor activation imparts susceptibility to severe upper-tract UTI in both female and male murine hosts. Visualization of intratubular UPEC communities illuminates early renal abscess pathogenesis and the role of abscess formation in preventing dissemination of infection. Additionally, our study suggests that androgen modulation may represent a novel therapeutic route to combat recalcitrant or recurrent UTI in a range of patient populations.

Androgens Enhance Male Urinary Tract Infection Severity in a New Model.

Urinary tract infections (UTIs) occur predominantly in females but also affect substantial male patient populations; indeed, morbidity in complicated UTI is higher in males. Because of technical obstacles, preclinical modeling of UTI in male mice has been limited. We devised a minimally invasive surgical bladder inoculation technique that yields reproducible upper and lower UTI in both male and female mice, enabling studies of sex differences in these infections. Acute uropathogenic Escherichia coli (UPEC) cystitis in C57BL/6 and C3H/HeN males recapitulated the intracellular bacterial community pathway previously shown in females. However, surgically infected females of these strains exhibited more robust bladder cytokine responses and more efficient UPEC control than males. Compared with females, C3H/HeN males displayed a striking predilection for chronic cystitis, manifesting as persistent bacteriuria, high-titer bladder bacterial burdens, and chronic inflammation. Furthermore, males developed more severe pyelonephritis and 100% penetrant renal abscess (a complication that is rare in female mice). These phenotypes were sharply abrogated after castration but restored with exogenous testosterone, suggesting that male susceptibility to UTI is strongly influenced by androgen exposure. These data substantiate the long-standing presumption that anatomic differences in urogenital anatomy confer protection from UTI in males; however, as clinically observed, male sex associated with more severe UTI once these traditional anatomic barriers were bypassed. This study introduces a highly tractable preclinical model for interrogating sex differences in UTI susceptibility and pathogenesis, and illuminates an interplay between host sex and UTI that is more complex than previously appreciated.

Tbx5 and Osr1 interact to regulate posterior second heart field cell cycle progression for cardiac septation.

RATIONALE: Mutations of TBX5 cause Holt-Oram syndrome (HOS) in humans, a disease characterized by atrial or occasionally ventricular septal defects in the heart and skeletal abnormalities of the upper extremity. Previous studies have demonstrated that Tbx5 regulates Osr1 expression in the second heart field (SHF) of E9.5 mouse embryos. However, it is unknown whether and how Tbx5 and Osr1 interact in atrial septation. OBJECTIVE: To determine if and how Tbx5 and Osr1 interact in the posterior SHF for cardiac septation. METHODS AND RESULTS: In the present study, genetic inducible fate mapping showed that Osr1-expressing cells contribute to atrial septum progenitors between E8.0 and E11.0. Osr1 expression in the pSHF was dependent on the level of Tbx5 at E8.5 and E9.5 but not E10.5, suggesting that the embryo stage before E10.5 is critical for Tbx5 interacting with Osr1 in atrial septation. Significantly more atrioventricular septal defects (AVSDs) were observed in embryos with compound haploinsufficiency for Tbx5 and Osr1. Conditional compound haploinsufficiency for Tbx5 and Osr1 resulted in a significant cell proliferation defect in the SHF, which was associated with fewer cells in the G2 and M phases and a decreased level of Cdk6 expression. Remarkably, genetically targeted disruption of Pten expression in atrial septum progenitors rescued AVSDs caused by Tbx5 and Osr1 compound haploinsufficiency. There was a significant decrease in Smo expression, which is a Hedgehog (Hh) signaling pathway modulator, in the pSHF of Osr1 knockout embryos at E9.5, implying a role for Osr1 in regulating Hh signaling. CONCLUSIONS: Tbx5 and Osr1 interact to regulate posterior SHF cell cycle progression for cardiac septation.

Small molecule inhibitors of Staphylococcus aureus RnpA alter cellular mRNA turnover, exhibit antimicrobial activity, and attenuate pathogenesis.

Methicillin-resistant Staphylococcus aureus is estimated to cause more U.S. deaths annually than HIV/AIDS. The emergence of hypervirulent and multidrug-resistant strains has further amplified public health concern and accentuated the need for new classes of antibiotics. RNA degradation is a required cellular process that could be exploited for novel antimicrobial drug development. However, such discovery efforts have been hindered because components of the Gram-positive RNA turnover machinery are incompletely defined. In the current study we found that the essential S. aureus protein, RnpA, catalyzes rRNA and mRNA digestion in vitro. Exploiting this activity, high through-put and secondary screening assays identified a small molecule inhibitor of RnpA-mediated in vitro RNA degradation. This agent was shown to limit cellular mRNA degradation and exhibited antimicrobial activity against predominant methicillin-resistant S. aureus (MRSA) lineages circulating throughout the U.S., vancomycin intermediate susceptible S. aureus (VISA), vancomycin resistant S. aureus (VRSA) and other Gram-positive bacterial pathogens with high RnpA amino acid conservation. We also found that this RnpA-inhibitor ameliorates disease in a systemic mouse infection model and has antimicrobial activity against biofilm-associated S. aureus. Taken together, these findings indicate that RnpA, either alone, as a component of the RNase P holoenzyme, and/or as a member of a more elaborate complex, may play a role in S. aureus RNA degradation and provide proof of principle for RNA catabolism-based antimicrobial therapy.

Inactivation of phospholipase D diminishes Acinetobacter baumannii pathogenesis.

Acinetobacter baumannii is an emerging bacterial pathogen of considerable health care concern. Nonetheless, relatively little is known about the organism's virulence factors or their regulatory networks. Septicemia and ventilator-associated pneumonia are two of the more severe forms of A. baumannii disease. To identify virulence factors that may contribute to these disease processes, genetically diverse A. baumannii clinical isolates were evaluated for the ability to proliferate in human serum. A transposon mutant library was created in a strain background that propagated well in serum and screened for members with decreased serum growth. The results revealed that disruption of A. baumannii phospholipase D (PLD) caused a reduction in the organism's ability to thrive in serum, a deficiency in epithelial cell invasion, and diminished pathogenesis in a murine model of pneumonia. Collectively, these results suggest that PLD is an A. baumannii virulence factor.

New approaches to detection and identification of Rickettsia africae and Ehrlichia ruminantium in Amblyomma variegatum (Acari: Ixodidae) ticks from the Caribbean.

Imported from Africa in the 1700s and despite frequent modern eradication efforts, Amblyomma variegatum (F.) spread through the Caribbean by cattle transport, small ruminants, and migrating birds. A. variegatum is a vector for Rickettsia africae, the causative agent of African tick bite fever, and Ehrlichia ruminantium, the causative agent of heartwater. We examined 95 A. variegatum and six Rhipicephalus (Boophilus) microplus (Canestrini) collected from cattle at an abattoir in Antigua. Engorged tick extracts adsorbed on Nobotu filter paper strips and new nested polymerase chain reaction (PCR) assays for E. ruminantium and Dermatophilus congolensis were used to evaluate these ticks for the presence of these pathogenic bacteria. Amblyomma ticks (62.4%) contained R. africae DNA by PCR/restriction fragment length polymorphism analysis and DNA sequencing of the OmpA and 17-kDa antigen genes. Twenty Amblyomma and two Rh. microplus contained E. ruminantium DNA. No E. chaffeensis, Anaplasma phagocytophilum, Coxiella burnetii, or D. congolensis DNA was detected in these ticks. The continued presence of Am. variegatum in the Caribbean poses a significant risk of infection in cattle with E. ruminantium and in humans by R. africae. Eradication efforts are essential to prevent the further spread of Am. variegatum.

A long-term maternal diet intervention is necessary to avoid the obesogenic effect of maternal high-fat diet in the offspring.

Although a pre-pregnancy dietary intervention is believed to be able to prevent offspring obesity, research evidence is absent. We hypothesize that a long period of pre-pregnancy maternal diet transition from a high-fat (HF) diet to a normal-fat (NF) diet effectively prevents offspring obesity, and this preventive effect is independent of maternal body weight change. In our study, female mice were either continued on an NF diet (NF group) or an HF diet (HF group) until weaning, or switched from an HF to an NF for 1 week (H1N group), 5 weeks (H5N group) or 9 weeks (H9N group) before pregnancy. After weaning, the offspring were given the HF diet for 12 weeks to promote obesity. The mothers, regardless of which group, did not display maternal body weight change and glucose intolerance either before pregnancy or after weaning. Compared to the HF group, the H1N and H5N, but not the H9N, offspring developed glucose intolerance earlier, with more severely imbalanced glucose homeostasis. These offspring also displayed hepatocyte degeneration and significant adipocyte hypertrophy associated with higher expression of lipogenesis genes. The molecular mechanistic study showed blunted insulin signaling, overactivated adipocyte Akt signaling and hepatic AMPK signaling with enhanced lipogenesis genes in the H1N and H5N versus the NF offspring. However, maternal H9N diets normalized glucose and lipid metabolism of the offspring via resensitized insulin signaling and normalized Akt and AMPK signaling. In summary, we showed that a long-term maternal diet intervention effectively released the intergenerational obesogenic effect of maternal HF diet independent of maternal weight management.

Renal scar formation and kidney function following antibiotic-treated murine pyelonephritis.

We present a new preclinical model to study treatment, resolution and sequelae of severe ascending pyelonephritis. Urinary tract infection (UTI), primarily caused by uropathogenic Escherichia coli (UPEC), is a common disease in children. Severe pyelonephritis is the primary cause of acquired renal scarring in childhood, which may eventually lead to hypertension and chronic kidney disease in a small but important fraction of patients. Preclinical modeling of UTI utilizes almost exclusively females, which (in most mouse strains) exhibit inherent resistance to severe ascending kidney infection; consequently, no existing preclinical model has assessed the consequences of recovery from pyelonephritis following antibiotic treatment. We recently published a novel mini-surgical bladder inoculation technique, with which male C3H/HeN mice develop robust ascending pyelonephritis, highly prevalent renal abscesses and evidence of fibrosis. Here, we devised and optimized an antibiotic treatment strategy within this male model to more closely reflect the clinical course of pyelonephritis. A 5-day ceftriaxone regimen initiated at the onset of abscess development achieved resolution of bladder and kidney infection. A minority of treated mice displayed persistent histological abscess at the end of treatment, despite microbiological cure of pyelonephritis; a matching fraction of mice 1 month later exhibited renal scars featuring fibrosis and ongoing inflammatory infiltrates. Successful antibiotic treatment preserved renal function in almost all infected mice, as assessed by biochemical markers 1 and 5 months post-treatment; hydronephrosis was observed as a late effect of treated pyelonephritis. An occasional mouse developed chronic kidney disease, generally reflecting the incidence of this late sequela in humans. In total, this model offers a platform to study the molecular pathogenesis of pyelonephritis, response to antibiotic therapy and emergence of sequelae, including fibrosis and renal scarring. Future studies in this system may inform adjunctive therapies that may reduce the long-term complications of this very common bacterial infection.

Subversion of Host Innate Immunity by Uropathogenic Escherichia coli.

Uropathogenic Escherichia coli (UPEC) cause the majority of community-onset urinary tract infections (UTI) and represent a major etiologic agent of healthcare-associated UTI. Introduction of UPEC into the mammalian urinary tract evokes a well-described inflammatory response, comprising pro-inflammatory cytokines and chemokines as well as cellular elements (neutrophils and macrophages). In human UTI, this inflammatory response contributes to symptomatology and provides means for diagnosis by standard clinical testing. Early in acute cystitis, as demonstrated in murine models, UPEC gains access to an intracellular niche that protects a population of replicating bacteria from arriving phagocytes. To ensure the establishment of this protected niche, UPEC employ multiple strategies to attenuate and delay the initiation of host inflammatory components, including epithelial secretion of chemoattractants. Recent work has also revealed novel mechanisms by which UPEC blunts neutrophil migration across infected uroepithelium. Taken together, these attributes distinguish UPEC from commensal and nonpathogenic E. coli strains. This review highlights the unique immune evasion and suppression strategies of this bacterial pathogen and offers directions for further study; molecular understanding of these mechanisms will inform the development of adjunctive, anti-virulence therapeutics for UTI.

A review of hypogonadism and erectile dysfunction among HIV-infected men during the pre- and post-HAART eras: diagnosis, pathogenesis, and management.

Hypogonadism and erectile dysfunction (ED) appear to be more common among men infected with HIV compared to age-matched men within the general U.S. population. HIV providers should consider these conditions and utilize standardized evaluation and diagnostic criteria. Treatment of both hypogonadism and ED increases sexual function and quality of life; testosterone supplementation in the setting of hypogonadism may also improve lean body mass, mental status, and anemia. We review the epidemiology, diagnosis, pathogenesis, and treatment options of both hypogonadism and ED among HIV-infected men.

History of U.S. military contributions to the study of bacterial zoonoses.

Bacterial zoonoses have afflicted campaigns throughout military history, at times playing an important role in determining their outcomes. In addition, zoonotic bacteria are among the leading biological warfare threats. The U.S. military medical services have been at the forefront of research to define the basic microbiology, ecology, epidemiology, and clinical aspects of these diseases. This historical review discusses the military significance of plague, Q fever, anthrax, leptospirosis, bartonellosis, tularemia, and brucellosis and the U.S. military medical research counteroffensive. These contributions have ranged from basic molecular biology to elegant epidemiological surveys, from defining pathogenesis to developing new vaccine candidates. In an era of emerging diseases and biological weapons, the U.S. military will continue to lead a dynamic research effort to counter these disease threats.

History of U.S. military contributions to the study of rickettsial diseases.

Rickettsial diseases have affected the military throughout history. Efforts such as those of the Joint U.S. Typhus Commission near the beginning of World War II and of military researchers since have reduced the impact of these diseases on U.S. and Allied forces. Despite the postwar development of effective antibiotic therapies, the newly emerging antibiotic-resistant scrub typhus rickettsial strains of the Asian Pacific region mandate continued research and surveillance. Similarly, tick-infested training areas in the United States and similar exposure abroad render the spotted fevers and the ehrlichioses problematic to deployed troops. The military continues to work on countermeasures to control the arthropod vectors, as well as actively participating in the development of rapid accurate diagnostic tests, vaccines, and improved surveillance methods. Several rickettsial diseases, including epidemic typhus, scrub typhus, the ehrlichioses, and the spotted fevers, are reviewed, with emphasis on the military historical significance and contributions.

The Epidemiology of Upper Extremity Fractures in the United States, 2009.

BACKGROUND: No single epidemiological study of upper extremity fractures exists in the United States using data from all payers. Current epidemiological estimates are based on case series, foreign databases, or Medicare data, which are not representative of the entire US population. The objective of this project was to accurately describe the incidence of fractures of the upper extremity in a representative sample of the US population. METHODS: Using International Classification of Disease, Ninth Edition codes for patient visits reported in the 2009 State Emergency Department Database and the State Inpatient Database, available from the Healthcare Cost and Utilization Project, and 2010 US Census data, we calculated the annual incidence rates per 10,000 persons of upper extremity fractures of all patients, regardless of age or payer type. This was done using a representative national sample from 8 states: Arizona, California, Iowa, Maryland, Massachusetts, New Jersey, and Vermont. RESULTS: Overall, in this population of over 87 million Americans, there were 590,193 fractures of the upper extremity, yielding an annual incidence of 67.6 fractures per 10,000 persons. Distal radius and ulna fractures were the most common upper extremity fractures (16.2 fractures per 10,000 persons), followed by hand fractures (phalangeal and metacarpal fractures; 12.5 and 8.4 per 10,000, respectively), proximal humerus fractures (6.0 per 10,000), and clavicle fractures (5.8 per 10,000). The most common type of fracture for all age groups was distal radius fractures, except in the 18- to 34-year-old group, in which metacarpal and phalangeal fractures were more common (16.1 and 12.5 per 10,000, respectively) and the 35- to 49-year-old group, in which phalangeal fractures were most common (11.5 per 10,000). The incidence of distal radius fractures was bimodal, with the highest rates in the under 18 and over 65 age groups (30.18 and 25.42 per 10,000, respectively) with lower rates in the middle age groups. The most common type of fracture for males was phalangeal fractures (11.5 per 10,000), and distal radius and ulna fractures were the most common type for females (11.8 per 10,000). Interestingly, phalangeal and metacarpal fractures varied by socioeconomic status (SES), which decreased with increasing SES. No other fracture type varied by SES. CONCLUSIONS: Epidemiological studies are necessary for research, clinical applications, and public health and health policy initiatives. This study reports national estimates of upper extremity fractures with subgroup analysis.

Endemic infectious diseases of Afghanistan.

The current crisis in Afghanistan has resulted in an influx of Western military personnel, peacekeepers, humanitarian workers, and journalists. At the same time, unprecedented numbers of internally displaced persons and refugees have overwhelmed much of the already fragile infrastructure, setting the stage for outbreaks of infectious diseases among both foreigners and local populations. This review surveys the literature concerning the infectious diseases of Afghanistan and south-central Asia, with particular emphasis on diseases not typically seen in the Western world.

Halting a pneumococcal pneumonia outbreak among United States Marine Corps trainees.

BACKGROUND: Streptococcus pneumoniae is the leading cause of bacterial pneumonia in all age groups. Identifying outbreaks of pneumococcal disease and key risk factors may lead to improvements in vaccination and prevention strategies for high-risk groups. A significant outbreak of S. pneumoniae pneumonia that occurred among Marine recruits is reported here. METHODS: An outbreak was investigated using standard microbiologic procedures and epidemiologic evaluation to define the extent of the outbreak, determine the microbiologic causative agent(s), identify risk factors for the development of disease, and institute preventive measures against further cases of pneumonia among recruits. RESULTS: Fifty-two cases of radiographically confirmed pneumonia occurred among 3367 Marine recruits over a 2-week period in November 2000. Twenty-five of these cases occurred in a single company of 481 men, with an attack rate of 5.2%. Twelve of the 25 cases were caused by S. pneumoniae, serotypes 4 and 9v. The outbreak rapidly ended following isolation of cases, prophylaxis with oral azithromycin, and administration of the 23-valent pneumococcal vaccine. CONCLUSIONS: This outbreak of pneumococcal disease occurred in the setting of intense military training and a crowded environment. The use of the pneumococcal vaccine year-round in military trainees and other high-risk populations to reduce pneumococcal disease should be considered.

Lumbar disc herniation in the Spine Patient Outcomes Research Trial: does educational attainment impact outcome?

STUDY DESIGN: Randomized trial with concurrent observational cohort. A total of 1171 patients were divided into subgroups by educational attainment: high school or less, some college, and college degree or above. OBJECTIVE: To assess the influence of education level on outcomes for treatment of lumbar disc herniation. SUMMARY OF BACKGROUND DATA: Educational attainment has been demonstrated to have an inverse relationship with pain perception, comorbidities, and mortality. METHODS: The Spine Patient Outcomes Research Trial enrolled surgical candidates (imaging-confirmed disc herniation with at least 6 weeks of persistent signs and symptoms of radiculopathy) from 13 multidisciplinary spine clinics in 11 US states. Treatments were standard open discectomy versus nonoperative treatment. Outcomes were changes from baseline for 36-Item Short Form Health Survey (SF-36), bodily pain (BP), and physical function (PF) scales and the modified Oswestry Disability Index (ODI) at 6 weeks, 3 months, 6 months, and yearly through 4 years. RESULTS: Substantial improvement was seen in all patient cohorts. Surgical outcomes did not differ by level of education. For nonoperative outcomes, however, higher levels of education were associated with significantly greater overall improvement over 4 years in BP (P = 0.007), PF (P = 0.001), and ODI (P = 0.003). At 4 years a "dose-response" type relationship was shown for BP (high school or less = 25.5, some college = 31, and college graduate or above = 36.3, P = 0.004) and results were similar for PF and ODI. The success of nonoperative treatment in the more educated cohort resulted in an attenuation of the relative benefit of surgery. CONCLUSION: Patients with higher educational attainment demonstrated significantly greater improvement with nonoperative treatment while educational attainment was not associated with surgical outcomes.