Tropheryma whipplei colonization in HIV-infected individuals is not associated with lung function or inflammation.

Studies demonstrate that Tropheryma whipplei (T. whipplei) is present in the lungs of healthy individuals without acute respiratory symptoms or acute respiratory infection and is more common in the lungs of HIV-infected individuals and in smokers. The impact of T. whipplei colonization in the lung on local inflammation and pulmonary dysfunction in HIV-infected individuals is currently unknown. In this study, we performed specific polymerase chain reaction (PCR) and sequencing for T. whipplei in bronchoalveolar lavage (BAL) and induced sputum (IS) samples in 76 HIV-infected participants from three clinical sites. Pulmonary function and proinflammatory cytokine and chemokine levels in BAL were measured. Frequency of T. whipplei in either BAL or IS was 43.4%. The sensitivity and specificity of IS compared to BAL for detection of T. whipplei was 92.3% and 84.2%, respectively, and isolates of T. whipplei in the BAL and IS in the same subject shared genetic identity. Pulmonary function measures were not associated with T. whipplei colonization, and proinflammatory cytokine and chemokine levels in BAL and plasma as well as percentages of inflammatory cells in BAL and IS were not higher in colonized individuals. Overall, these results indicate that T. whipplei colonization in the lung is common, but may not be associated with decreased pulmonary function or inflammation in HIV-infected individuals.

Mycorrhiza-induced alleviation of plant disease caused by Clavibacter michiganensis subsp. michiganensis and role of ethylene in mycorrhiza-induced resistance in tomato.

The protective role of arbuscular mycorrhizal fungi (AMF) against the phytopathogen Clavibacter michiganensis subsp. michiganensis (Cmm) was examined in tomato plants. Seven different AMF isolates were used to determine which ones were able to induce effectively resistance against Cmm. Stems of seven-week tomato plants were infected with Cmm, then a disease severity index (DSI) was determined during the next three weeks. In addition to different responses to mycorrhizal inoculation, three levels of responses to the bacterial disease were recognized in treatments. Plants inoculated with Rhizophagus irregularis (Ri) showed both the highest colonization and the highest induced resistance to Cmm while the effect of Funneliformis mosseae, Gigaspora margarita and Claroideoglomus claroideum on mycorrhizal colonization and on the induced resistance were intermediate and high, respectively. Subsequently, Ri was chosen to inoculate ethylene-insensitive tomato mutant line Never ripe (Nr) and its background (Pearson) to investigate the possible role of ethylene (ET) in the mycorrhiza-induced resistance (MIR). The results showed that Ri could induce systemic resistance against Cmm in the Pearson background, whereas ET-insensitivity in Nr plants impaired MIR. These results suggest that ET is required for Ri-induced resistance against Cmm. To our knowledge, this is the first study to examine the effect of different AMF isolates on the response of tomato plants to Cmm and involvement of ET in MIR against Cmm.

Unusual Extrapulmonary Rhodococcus Equi Infection in a Kidney Transplant Patient.

Rhodococcus equi is a well-recognized pathogen in veterinary medicine that can also affect immuno-compromised human subjects. The most common clinical features in humans include necrotizing pneumonia with subacute pulmonary disease, progressive cough, chest pain and fever. We report a case of a 49-year-old kidney transplant patient who developed a Rhodococcus equi infection characterized by multiple abscesses of the soft tissues and muscles without any respiratory manifestation. Combining specific antibiotic therapy and surgical management of the abscesses without immunosuppression discontinuation led to a complete recovery of both patient and graft.

Peritoneal-dialysis related peritonitis caused by Gordonia species: report of four cases and literature review.

AIM: To investigate the clinical course and outcome of peritoneal dialysis-associated peritonitis secondary to Gordonia species. METHOD: We reviewed all Gordonia peritonitis episodes occurring in a single dialysis unit from 1994 to 2013. RESULTS: During the study period, four episodes of Gordonia peritonitis were recorded. All were male patients. One patient responded to vancomycin therapy. One patient had refractory peritonitis despite vancomycin, but responded to imipenem and amikacin combination therapy. One patient had relapsing peritonitis and required catheter removal. The fourth patient had an elective Tenckhoff catheter exchange. No patient died of peritonitis. Causative organism was not fully identified until 7 to 18 days of peritonitis. CONCLUSION: Gordonia species is increasingly recognized to cause serious infections. In patients undergoing peritoneal dialysis, Gordonia peritonitis should be considered in case of refractory Gram-positive bacilli peritonitis, especially when the exact organism could not be identified one week after the onset of peritonitis. A close liaison with a microbiologist is needed for a timely diagnosis.

Clinical characteristics of infections caused by Tsukamurella spp. and antimicrobial susceptibilities of the isolates.

To investigate the clinical and microbiological characteristics of infections caused by Tsukamurella spp., the computerised database of the Bacteriology Laboratory at National Taiwan University Hospital (Taipei, Taiwan) was reviewed retrospectively to identify patients with infections caused by this species during the period January 1997 to December 2008. All of the isolates had been initially misidentified as Rhodococcus spp. Identification of Tsukamurella isolates to species level was carried out by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis of the heat shock protein gene (hsp65) as well as 16S rRNA gene sequencing. During the study period, a total of eight patients with Tsukamurella infection and two patients with Tsukamurella colonisation were identified. Tsukamurella tyrosinosolvens (n=6) was the most prevalent species, followed by Tsukamurella spumae (n=3) and Tsukamurella pulmonis (n=1). Keratitis was the most common type of infection (n=3), followed by catheter-related bloodstream infection (n=2). One of the patients with Tsukamurella infection died due to bacteraemia; the other seven patients with Tsukamurella infection had favourable outcomes. The three species had different drug susceptibility patterns; T. pulmonis was the most resistant pathogen, with higher minimum inhibitory concentrations of clindamycin (>2 mg/L), erythromycin (2 mg/L) and tetracycline (8 mg/L) than those for the other Tsukamurella spp. In conclusion, strains of Tsukamurella spp., including T. spumae, are uncommon causative agents of ocular infections and bacteraemia in cancer patients. Molecular diagnostic methods are essential to distinguish species in the Tsukamurella genus from species in other phylogenetically related genera such as Rhodococcus.

Bearded dragons (Pogona vitticeps) asymptomatically infected with Devriesea agamarum are a source of persistent clinical infection in captive colonies of dab lizards (Uromastyx sp.).

Devriesea agamarum causes dermatitis and septicaemia in a variety of lizards, notably those belonging to the genus Uromastyx, whereas other species such as bearded dragons (Pogona vitticeps) seem to be asymptomatic carriers. Using amplified fragment length polymorphism (AFLP), the relatedness between 69 D. agamarum isolates was examined. The isolates derived from 44 diseased lizards, of which 31 belonged to the genus Uromastyx, and from 25 healthy lizards, of which 21 were bearded dragons. Eight AFLP genotypes were obtained, four of which comprised 93% of the isolates. These four genotypes were each present in 2, 2, 8 and 13 different captive colonies. Up to three genotypes were isolated from a single infected colony simultaneously. On two occasions, the same genotype was found in healthy bearded dragons and diseased Uromastyx lizards from the same colony, confirming the role of the former as an asymptomatic source of infection for the latter. Two genotypes, comprising 12 isolates, were exclusively associated with diseased Uromastyx lizards, suggesting strain dependent host adaptation. Finally, D. agamarum was shown to be able to persist for at least seven years in a lizard colony, persistently causing severe disease in several lizard species.

Phospholipase D promotes Arcanobacterium haemolyticum adhesion via lipid raft remodeling and host cell death following bacterial invasion.

BACKGROUND: Arcanobacterium haemolyticum is an emerging bacterial pathogen, causing pharyngitis and more invasive infections. This organism expresses an unusual phospholipase D (PLD), which we propose promotes bacterial pathogenesis through its action on host cell membranes. The pld gene is found on a genomic region of reduced %G + C, suggesting recent horizontal acquisition. RESULTS: Recombinant PLD rearranged HeLa cell lipid rafts in a dose-dependent manner and this was inhibited by cholesterol sequestration. PLD also promoted host cell adhesion, as a pld mutant had a 60.3% reduction in its ability to adhere to HeLa cells as compared to the wild type. Conversely, the pld mutant appeared to invade HeLa cells approximately two-fold more efficiently as the wild type. This finding was attributable to a significant loss of host cell viability following secretion of PLD from intracellular bacteria. As determined by viability assay, only 15.6% and 82.3% of HeLa cells remained viable following invasion by the wild type or pld mutant, respectively, as compared to untreated HeLa cells. Transmission electron microscopy of HeLa cells inoculated with A. haemolyticum strains revealed that the pld mutant was contained within intracellular vacuoles, as compared to the wild type, which escaped the vacuole. Wild type-infected HeLa cells also displayed the hallmarks of necrosis. Similarly inoculated HeLa cells displayed no signs of apoptosis, as measured by induction of caspase 3/7, 8 or 9 activities. CONCLUSIONS: These data indicate that PLD enhances bacterial adhesion and promotes host cell necrosis following invasion, and therefore, may be important in the disease pathogenesis of A. haemolyticum infections.

Tropheryma whipplei in children with gastroenteritis.

Tropheryma whipplei, which causes Whipple disease, is found in human feces and may cause gastroenteritis. To show that T. whipplei causes gastroenteritis, PCRs for T. whipplei were conducted with feces from children 2-4 years of age. Western blotting was performed for samples from children with diarrhea who had positive or negative results for T. whipplei. T. whipplei was found in samples from 36 (15%) of 241 children with gastroenteritis and associated with other diarrheal pathogens in 13 (33%) of 36. No positive specimen was detected for controls of the same age (0/47; p = 0.008). Bacterial loads in case-patients were as high as those in patients with Whipple disease and significantly higher than those in adult asymptomatic carriers (p = 0.002). High incidence in patients and evidence of clonal circulation suggests that some cases of gastroenteritis are caused or exacerbated by T. whipplei, which may be co-transmitted with other intestinal pathogens.

Propionibacterium endocarditis: a case series from the International Collaboration on Endocarditis Merged Database and Prospective Cohort Study.

Propionibacterium species are occasionally associated with serious systemic infections such as infective endocarditis. In this study, we examined the clinical features, complications and outcome of 15 patients with Propionibacterium endocarditis using the International Collaboration on Endocarditis Merged Database (ICE-MD) and Prospective Cohort Study (ICE-PCS), and compared the results to 28 cases previously reported in the literature. In the ICE database, 11 of 15 patients were male with a mean age of 52 y. Prosthetic valve endocarditis occurred in 13 of 15 cases and 3 patients had a history of congenital heart disease. Clinical findings included valvular vegetations (9 patients), cardiac abscesses (3 patients), congestive heart failure (2 patients), and central nervous system emboli (2 patients). Most patients were treated with beta-lactam antibiotics alone or in combination for 4 to 6 weeks. 10 of the 15 patients underwent valve replacement surgery and 2 patients died. Similar findings were noted on review of the literature. The results of this paper suggest that risk factors for Propionibacterium endocarditis include male gender, presence of prosthetic valves and congenital heart disease. The clinical course is characterized by complications such as valvular dehiscence, cardiac abscesses and congestive heart failure. Treatment may require a combination of medical and surgical therapy.

The effects of Arcanobacterium pyogenes on endometrial function in vitro, and on uterine and ovarian function in vivo.

Uterine bacterial infection after parturition causes endometritis, perturbs ovarian function and leads to infertility in cattle. Although endometritis is caused by mixed infections, endometrial pathology is associated with the presence of Arcanobacterium pyogenes. The aims of the present study were to determine the effects of A. pyogenes on endometrial function in vitro, and on uterine and ovarian function in vivo. Heat-killed A. pyogenes did not affect the production of prostaglandin F2alpha (PGF) or prostaglandin E(2) (PGE) from endometrial explants, or purified populations of endometrial epithelial or stromal cells. However, the explants produced more PGF and PGE than controls when treated with a bacteria-free filtrate (BFF) cultured from A. pyogenes. Similarly, BFF stimulated PGF and PGE production by epithelial and stromal cells, respectively. So, BFF or control PBS was infused into the uterus of heifers (n=7 per group) for 8 days, starting the day after estrus. Emergence of the follicle wave, dominant follicle or corpus luteum diameter, and peripheral plasma FSH, LH, estradiol, progesterone, PGFM, or acute phase protein concentrations were unaffected by the BFF infusion. In the live animal it is likely that the intact uterine mucosa limits the exposure of the endometrial cells to the exotoxin of A. pyogenes, whereas the cells are readily exposed to the toxin in vitro.

Eight cases of lower respiratory tract infection caused by Stomatococcus mucilaginosus.

Stomatococcus mucilaginosus was isolated from 8 patients suffering from lower respiratory tract infections over a 4-y period (1999-2003). The infections ranged from mild cases of pneumonia to a life-threatening case of recurrent lung abscesses in a neutropenic patient. The various strains were cultured from specimens obtained by bronchoscopy, blood, and sputum specimens. All strains were fully susceptible to rifampicin, vancomycin and gentamicin. They showed variable susceptibility to penicillin and ciprofloxacin. S. mucilaginosus is likely to be under-reported as a pathogen due to difficulties in obtaining samples for culture as well as misidentification due to its biochemical characteristics.

Invasive Streptomyces infections: six cases and literature review.

Streptomyces are saprophytic soil organisms rarely known to cause invasive infections other than mycetoma. We report 6 cases of invasive Streptomyces infections and review 13 previously reported cases. Our series included 2 cases of lung abscess or pneumonitis, 3 cases of central venous catheter-related bloodstream infection, and I case of possible hypersensitivity pneumonitis. Most previous cases also included lung infections and bloodstream infections. Preexisting conditions, such as cancer, AIDS or HIV infection, presence of a central venous catheter, and prosthetic heart valve, were present in all cases since 1985. Diverse Streptomyces species were involved, consistent with the highly opportunistic nature of the infections. Clinical management depended on the clinical situation of individual cases without consensus. Available susceptibility data showed that Streptomyces organisms were consistently susceptible to amikacin; frequently susceptible to imipenem, clarithromycin or erythromycin, minocycline, and trimethoprim-sulfamethoxazole; and infrequently susceptible to ciprofloxacin and ampicillin. The diagnosis of Streptomyces infection required microbiologic and pathologic correlation to rule out contamination.

Murine model of infection by Tropheryma whipplei.

We developed an animal model reproducing several aspects of Whipple's disease. Immunocompetent mice were persistently infected with Tropheryma whipplei, its etiological agent, and developed liver granulomas. SCID mice were infected similarly but did not develop tissue lesions. The delayed clearance of T. whipplei suggests a protective role for innate immunity.

Two cases of equine abortion caused by Rhodococcus equi.

Rhodococcus equi was isolated from lung, liver, spleen, and stomach content of two aborted equine fetuses of 7 and 8 months gestation from two different farms. Lesions included diffuse pyogranulomatous pneumonia with numerous Gram-positive coccobacilli within the cytoplasm of macrophages, multinucleated Langhans giant cells and neutrophils, and enhanced extramedullary hematopoiesis with megakaryocytosis within the liver and spleen. Detection of R. equi was made by bacteriology and immunohistochemistry for R. equi and VapA, the virulence factor of R. equi. R. equi and VapA were identified within the lungs of both fetuses, and its distribution correlated with lesions. Fetal lesions were similar to those observed in foals. We speculate that the fetuses contracted infection from the placenta by normal breathing movements or by swallowing of the amniotic fluid contaminated with R. equi.

Effect of pathogen-specific clinical mastitis on milk yield in dairy cows.

Our objective was to estimate the effects of the first occurrence of pathogen-specific clinical mastitis (CM) on milk yield in 3071 dairy cows in 2 New York State farms. The pathogens studied were Streptococcus spp.,Staphylococcus aureus, Staphylococcus spp., Escherichia coli, Klebsiella spp., Arcanobacterium pyogenes, other pathogens grouped together, and "no pathogen isolated." Data were collected from October 1999 to July 2001. Milk samples were collected from cows showing signs of CM and were sent to the Quality Milk Production Services laboratory at Cornell University for microbiological culture. The SAS statistical procedure PROC MIXED, with an autoregressive covariance structure, was used to quantify the effect of CM and several other control variables (herd, calving season, parity, month of lactation, J-5 vaccination status, and other diseases) on weekly milk yield. Separate models were fitted for primipara and multipara, because of the different shapes of their lactation curves. To observe effects of mastitis, milk weights were divided into several periods both pre- and postdiagnosis, according to when they were measured in relation to disease occurrence. Another category contained cows without the type of CM being modeled. Because all pathogens were modeled simultaneously, a control cow was one without CM. Among primipara, Staph. aureus, E. coli, Klebsiella spp., and "no pathogen isolated" caused the greatest losses. Milk yield generally began to drop 1 or 2 wk before diagnosis; the greatest loss occurred immediately following diagnosis. Mastitic cows often never recovered their potential yield. Among older cows, Streptococcus spp., Staph. aureus, A. pyogenes, E. coli, and Klebsiella spp. caused the most significant losses. Many multipara that developed CM were actually higher producers before diagnosis than their nonmastitic herd-mates. As in primipara, milk yield in multipara often began to decline shortly before diagnosis; the greatest loss occurred immediately following diagnosis. Milk loss persisted until at least 70 d after diagnosis for Streptococcus spp., Klebsiella spp., and A. pyogenes. The tendency for higher producing cows to contract CM may mask its impact on cow health and production. These findings provide dairy producers with more information on which pathogen-specific CM cases should receive treatment and how to manage these cows, thereby reducing CM impact on cow well being and profitability.

Mucosal immune response to Tropheryma whipplei.

Whipple's disease is a rare infectious disease caused by the ubiquitously occurring Tropheryma whipplei in predisposed persons. Genetic or acquired defects in the mucosal and peripheral immune system become apparent as diminished Th1 immune functions with decreased production of IL-12 and IFN-gamma accompanied by an increased secretion of IL-4. These defects may enable T. whipplei to survive and replicate. The recently established cultivation of the bacterium in HEL cells and the isolation from infected intestinal biopsies enable a multitude of experimental possibilities which may lead to an improved diagnosis as well as understanding of the etiology and pathogenesis of Whipple's disease.

Gas exchange during intense exercise in Standardbreds with earlier Rhodococcus equi pneumonia.

It is not known if pulmonary function and gas exchange during exercise are altered after pyogranulomatous pneumonia caused by Rhodococcus equi infection in the foal. The aim was to evaluate whether pulmonary gas exchange during high intensity exercise was altered in mature Standardbreds with a history of R. equi pneumonia as foals. In 7 foals, R. equi pneumonia was confirmed and treated. At age 3 years, when these horses were subjected to professional training, an inclined treadmill exercise test including 4 speeds was performed. Samples were collected when a steady state in VO2 was obtained. Red cell volume, heart rate, respiratory rate, and systemic and pulmonary mean arterial pressures were measured and cardiac output calculated. Oxygen and carbon dioxide tensions in arterial and mixed venous blood were analysed. The alveolar ventilation and the alveolar-arterial oxygen tension difference were determined. Pulmonary gas exchange was assessed and the ventilation-perfusion distribution, VA/Q, was estimated by the multiple inert gas elimination technique. Ventilation-perfusion mismatch and shunt were determined and diffusion limitation calculated. The gas exchange in Standardbred trotters previously infected with R. equi and successfully treated was not compromised during intense treadmill exercise compared with reference values for healthy, fit Standardbreds. We conclude that adult Standardbreds trotters with diagnosed R. equi pneumonia as foals, can achieve an adequate gas exchange at a workload close to VO2peak.

Lochial secretions of Escherichia coli- or Arcanobacterium pyogenes-infected bovine uteri modulate the phenotype and the functional capacity of neutrophilic granulocytes.

It has been suggested that in cases of puerperal endometritis of cattle infected with Escherichia coli and Arcanobacterium pyogenes, the neutrophils are compromised in their defense capacity or downregulated functionally. In addition to direct bacterial effects, contents of lochial secretions and secreted products of locally activated polymorphonuclear neutrophilic granulocytes (PMNs) may also account for changes in function of freshly immigrating neutrophils. In this study, lochial secretions were obtained from healthy cows and from cows infected by E. coli or A. pyogenes. Separated uterine PMN of infected cows displayed an altered phenotype and function which correlated with the degree of bacterial contamination. Concurrently tested circulating PMN showed no such changes. Infected lochial secretions sterilized by filtration also changed the phenotype of blood PMN. Lochial secretions of healthy cows displayed only minor effects. The effects on PMN function in infected cows varied: ingestion was less affected, whereas generation of reactive oxygen species (ROS) was severely depressed. Concurrently tested purified bacterial products (solubles and fragments) of E. coli and A. pyogenes did not induce the phenotypical and functional changes observed in blood PMN. Since infected lochia also contained high numbers of immigrated and probably activated PMN, the influence of supernatants from phorbol myristate acetate-activated PMN were tested on freshly isolated blood PMN. Such supernatants also increased the expression of certain surface molecules and inhibited the ROS generation. Thus, reduced function and altered phenotypes of PMN which immigrate into the uteri of cows with bacterial endometritis is due not only to interactions with bacteria or bacterial products, but is also to the uterine milieu.

Rhodococcus equi: an emerging pathogen.

More than 100 cases of Rhodococcus equi infection have been reported since the first description of human disease caused by this organism. The vast majority of patients infected with R. equi are immunocompromised, and two-thirds have human immunodeficiency virus infection. The clinical manifestations of R. equi infection are diverse, although 80% of patients have some pulmonary involvement. The organism is easily cultured from specimens of infected tissue or body fluid, but it may be misdiagnosed as a contaminant. Treatment is often prolonged, and relapses at distant sites are common. This article summarizes the history, diagnosis, clinical features, and treatment of infection with this emerging pathogen.