Interleukin-13 promotes susceptibility to chlamydial infection of the respiratory and genital tracts

Chlamydiae are intracellular bacteria that commonly cause infections of the respiratory and genital tracts, which are major clinical problems. Infections are also linked to the aetiology of diseases such as asthma, emphysema and heart disease. The clinical management of infection is problematic and antibiotic resistance is emerging. Increased understanding of immune processes that are involved in both clearance and immunopathology of chlamydial infection is critical for the development of improved treatment strategies. Here, we show that IL-13 was produced in the lungs of mice rapidly after Chlamydia muridarum (Cmu) infection and promoted susceptibility to infection. Wild-type (WT) mice had increased disease severity, bacterial load and associated inflammation compared to IL-13 deficient (−/−) mice as early as 3 days post infection (p.i.). Intratracheal instillation of IL-13 enhanced bacterial load in IL-13−/− mice. There were no differences in early IFN-g and IL-10 expression between WT and IL-13−/− mice and depletion of CD4+ T cells did not affect infection in IL-13−/− mice. Collectively, these data demonstrate a lack of CD4+ T cell involvement and a novel role for IL-13 in innate responses to infection. We also showed that IL-13 deficiency increased macrophage uptake of Cmu in vitro and in vivo. Moreover, the depletion of IL-13 during infection of lung epithelial cells in vitro decreased the percentage of infected cells and reduced bacterial growth. Our results suggest that enhanced IL-13 responses in the airways, such as that found in asthmatics, may promote susceptibility to chlamydial lung infection. Importantly the role of IL-13 in regulating infection was not limited to the lung as we showed that IL-13 also promoted susceptibility to Cmu genital tract infection. Collectively our findings demonstrate that innate IL-13 release promotes infection that results in enhanced inflammation and have broad implications for the treatment of chlamydial infections and IL-13-associated diseases.

The intraocular pressure response to dehydration : a pilot study

This study was designed to determine the Intraocular Pressure (IOP) response to differing levels of dehydration. Seven males participated in a 90 minute treadmill walk (5 km/h and 1 % grade) in both a cool (22 °C) and hot (43 °C) climate. At Baseline and at 30 minute intervals measurements of IOP, by tonometery, and indicators of hydration status (nude weight and plasma osmolality (Posm)) were taken. Body temperature and heart rate were also measured at these time points. Statistically significant interactions (time point (4) by trial (2)) were observed for IOP (F = 10.747, p = 0.009) and body weight loss (F = 50.083, p < 0.001) to decrease, and Posm (F = 34.867, p < 0.001) to increase, by a significantly greater amount during the hot trial compared to the cool. A univariate general linear model showed a significant relationship between IOP and body weight loss (F = 37.63, p < 0.001) and Posm (F = 38.53, p < 0.001). A significant interaction was observed for body temperature (F = 20.908, p < 0.001) and heart rate (F = 25.487, p < 0.001) between the trials and time points, but there was negligible association between these variables and IOP (Pearson correlation coefficient < ±0.5). The present study provides evidence to suggest that IOP is influenced by hydration status.

Wolbachia-mediated resistance to dengue virus infection and death at the cellular level

Dengue is currently the most important arthropod-borne viral disease of humans. Recent work has shown dengue virus displays limited replication in its primary vector, the mosquito Aedes aegypti, when the insect harbors the endosymbiotic bacterium Wolbachia pipientis. Wolbachia-mediated inhibition of virus replication may lead to novel methods of arboviral control, yet the functional and cellular mechanisms that underpin it are unknown.

The open window of susceptibility to infection after acute exercise in healthy young male elite athletes

The 'open window' theory is characterised by short term suppression of the immune system following an acute bout of endurance exercise. This window of opportunity may allow for an increase in susceptibility to upper respiratory illness (URI). Many studies have indicated a decrease in immune function in response to exercise. However, many studies do not indicate changes in immune function past 2 hours after the completion of exercise, consequently failing to determine whether these immune cells numbers, or importantly their function, return to resting levels before the start of another bout of exercise. Ten male 'A' grade cyclists (age 24.2 +/- 5.3 years; body mass 73.8 +/- 6.5 kg; VO(2peak) 65.9 +/- 7.1 mL.kg(-1).min(-1)) exercised for two hours at 90% of their second ventilatory threshold. Blood samples were collected pre-, immediately post-, 2 hours, 4 hours, 6 hours, 8 hours, and 24 hours post-exercise. Immune variables examined included total leukocyte counts, neutrophil function (oxidative burst and phagocytic function), lymphocyte subset counts (CD4(+), CD8(+), and CD16(+)/56(+)), natural killer cell activity (NKCA), and NK phenotypes (CD56(dim)CD16(+), and CD56(bright)CD16(-)). There was a significant increase in total lymphocyte numbers from pre-, to immediately post-exercise (p<0.01), followed by a significant decrease at 2 hours post-exercise (p<0.001). CD4(+) T-cell counts significantly increased from pre-exercise, to 4 hours post- (p<0.05), and 6 hours post-exercise (p<0.01). However, NK (CD16(+)/56(+)) cell numbers decreased significantly from pre-exercise to 4 h post-exercise (p<0.05), to 6 h post-exercise (p<0.05), and to 8 h post-exercise (p<0.01). In contrast, CD56(bright)CD16- NK cell counts significantly increased from pre-exercise to immediately post-exercise (p<0.01). Neutrophil oxidative burst activity did not significantly change in response to exercise, while neutrophil cell counts significantly increased from pre-exercise, to immediately post-exercise (p<0.05), and 2 hours post-exercise (p<0.01), and remained significantly above pre-exercise levels to 8 hours post-exercise (p<0.01). Neutrophil phagocytic function significantly decreased from 2 hours post-exercise, to 6 hours post- (p<0.05), and 24 hours post-exercise (p<0.05). Finally, eosinophil cell counts significantly increased from 2 hours post to 6 hours post- (p<0.05), and 8 hours post-exercise (p<0.05). This is the first study to show changes in immunological variables up to 8 hours post-exercise, including significant NK cell suppression, NK cell phenotype changes, a significant increase in total lymphocyte counts, and a significant increase in eosinophil cell counts all at 8 hours post-exercise. Suppression of total lymphocyte counts, NK cell counts and neutrophil phagocytic function following exercise may be important in the increased rate of URI in response to regular intense endurance training.

Vaccination to protect against infection of the female reproductive tract

Infection of the female genital tract can result in serious morbidities and mortalities from reproductive disability, pelvic inflammatory disease and cancer, to impacts on the fetus, such as infant blindness. While therapeutic agents are available, frequent testing and treatment is required to prevent the occurrence of the severe disease sequelae. Hence, sexually transmitted infections remain a major public health burden with ongoing social and economic barriers to prevention and treatment. Unfortunately, while there are two success stories in the development of vaccines to protect against HPV infection of the female reproductive tract, many serious infectious agents impacting on the female reproductive tract still have no vaccines available. Vaccination to prevent infection of the female reproductive tract is an inherently difficult target, with many impacting factors, such as appropriate vaccination strategies/mechanisms to induce a suitable protective response locally in the genital tract, variation in the local immune responses due to the hormonal cycle, selection of vaccine antigen(s) that confers effective protection against multiple variants of a single pathogen (e.g., the different serovars of Chlamydia trachomatis) and timing of the vaccine administration prior to infection exposure. Despite these difficulties, there are numerous ongoing efforts to develop effective vaccines against these infectious agents and it is likely that this important human health field will see further major developments in the next 5 years.

Antenatal ureaplasma infection impairs development of the fetal ovine gut in an IL-1-dependent manner

Ureaplasma infection of the amniotic cavity is associated with adverse postnatal intestinal outcomes. We tested whether interleukin-1 (IL-1) signaling underlies intestinal pathology following ureaplasma exposure in fetal sheep. Pregnant ewes received intra-amniotic injections of ureaplasma or culture media for controls at 3, 7, and 14 d before preterm delivery at 124 d gestation (term 150 d). Intra-amniotic injections of recombinant human interleukin IL-1 receptor antagonist (rhIL-1ra) or saline for controls  were given 3 h before and every 2 d after Ureaplasma injection. Ureaplasma exposure caused fetal gut inflammation within 7 d with damaged villus epithelium and gut barrier loss. Proliferation, differentiation, and maturation of enterocytes were significantly reduced after 7 d of ureaplasma exposure, leading to severe villus atrophy at 14 d. Inflammation, impaired development and villus atrophy of the fetal gut was largely prevented by intra-uterine rhIL-1ra treatment. These data form the basis for a clinical understanding of the role of ureaplasma in postnatal intestinal pathologies.

A cost-outcome description of the septic work-up for bacterial infection in neonates in a tertiary care hospital

Analysis of the septic work-up of 194 neonates at Women's College Hospital, Toronto, showed that the only antepartum condition predicting neonatal sepsis was the mother being on antibiotics. The only postnatal condition predicting sepsis was a maternal postpartum white blood cell count over 11,000. The average cost for tests for a septic work-up in these 194 mother-neonate pairs was $71.48 (Canadian dollars), and the average cost of tests to find a septic case was $1,066.77.

Predictors of sexually transmitted infection in Australian women : evidence from the Australian longitudinal study on women’s health

This longitudinal study examined characteristics of women diagnosed with sexually transmitted infections (STI) for the first time in their later 20s and early 30s. Participants were 6,840 women (born 1973–1978) from the Australian Longitudinal Study on Women’s Health. Women aged 18–23 years were surveyed in 1996 (S1), 2000 (S2), 2003 (S3), and 2006 (S4). There were 269 women reporting an STI for the first time at S3 or S4. Using two multivariable logistic regression analyses (examining 18 predictor variables), these 269 women were compared (1) with 306 women who reported an STI at S2 and (2) with 5,214 women who never reported an STI across the four surveys. Women who reported an STI for the first time at S3 or S4 were less likely to have been pregnant or had a recent Pap smear compared to women reporting an STI at S2.Women reporting a first STI at S3 or S4 were less likely to have been pregnant or had a recent Pap smear compared to women reporting an STI at S2. Women were more likely to report an STI for the first time at S3 or S4 compared to women not reporting an STI at any survey if they were younger, unpartnered, had a higher number of sexual partners, had never been pregnant, were recently divorced or separated, and reported poorer access to Women’s Health or Family Planning Centres at S2. These findings demonstrate the value of longitudinal studies of sexual health over the life course beyond adolescence.

Evolving and expanding : the scope of practice of the infection control practitioner

Infection control practitioners (ICPs) work across the full spectrum of health care settings and carry out a broad range of practice activities. Whilst several studies have reported on the role of the ICP, there has been little investigation of the scope of infection control practice. This knowledge is essential to inform the professional, legal, educational and financial implications of this specialist role. One hundred and thirteen ICPs from a range of health care settings across Queensland were surveyed. Respondents were asked to rate the extent to which they were and should be engaging in the range of practices identified by Gardner, Jones & Olesen (1999). Significant differences were evident between what ICPs said was their actual practice versus what they thought they should be doing. Overall, the respondents consistently reported that they should be engaging in more of the range of infection control activities than they were, particularly with regard to management practices. A number of differences were found according to the context in which the practitioners worked, such as the type and size of facility and their employment status. The results of this study indicate that the scope of infection control practice has clearly moved beyond those practices that are confined by the hospital wall and defined by surveillance activities.

Use of focus group technique to investigate infection control practice

Use of focus groups as a technique of inquiry is gaining attention in the area of health-care research. This paper will report on the technique of focus group interviewing to investigate the role of the infection control practitioner. Infection control is examined as a specialty area of health-care practice that has received little research attention to date. Additionally, it is an area of practice that is expanding in response to social, economic and microbiological forces. The focus group technique in this study helped a group of infection control practitioners from urban, regional and rural areas throughout Queensland identify and categorise their daily work activities. The outcomes of this process were then analysed to identify the growth in breadth and complexity of the role of the infection control practitioner in the contemporary health-care environment. Findings indicate that the role of the infection control practitioner in Australia has undergone changes consistent with and reflecting changing models of health-care delivery.

The human dimension of nosocomial wound infection : a study in liminality

Nosocomial wound infection is a disease that has to date been primarily understood through the language of science and biomedicine. This paper reports on findings from a sociological, interpretive study that focused on the experiential dimension of this phenomenon. The illness experience of a nosocomial wound infection is examined within a cultural milieu that values the smooth, untroubled body and alternatively ascribes cultural meaning to a body that has a definable illness. Within this context the person with a chronic wound from nosocomial infection defies normative categorisation and is thus situated outside the patterning of society. The human dimension of nosocomial wound infection includes the private, existential and embodied aspects of living with a chronic, infected wound. This report indicates that the experiential dimension is characterised by an embodied state of liminality. People with this illness live an indeterminate existence that is in-between health and illness, cure and disease. As such they have no recognised place in the medical or social world.

Research report : computer surfaces and cross-infection

The computer is fast becoming part of the furniture in many hospital settings. Increasing reliance on the computer for documentation and dissemination of information in patient-care areas has increased the need to consider this equipment as a potential environmental reservoir for microorganisms. This paper reports on a small experimental study which investigated the potential role of computers in cross-infection. The results indicate that computer surfaces are similar to other environmental surfaces and carry the same risks for cross-infection.