Screening pregnant women for chlamydia : what are the predictors of infection?

Objectives: To determine the risk factors associated with chlamydial infection in pregnancy and the sensitivity and specificity of these when used for selective screening.

Methods: A prospective, cross-sectional study of pregnant women aged 16–25 years attending four major public antenatal services across Melbourne, Australia. Between October 2006 and July 2007, women were approached consecutively and asked to complete a questionnaire and to provide a first-pass urine specimen for Chlamydia trachomatis testing using PCR.

Results: Of 1180 eligible women, 1087 were approached and 1044 (88%) consented to participate. Among the 987 women for whom a questionnaire and a definitive diagnostic assay were available, the prevalence of chlamydia was 3.2% (95% CI 1.8 to 5.9). In a multiple logistic regression model, more than one sexual partner in the past year (AOR 11.5; 95% CI 7.1 to 18.5) was associated with chlamydia infection. The use of any antibiotic within 3 months (AOR 0.2; 95% CI 0.1 to 0.6) was associated with a decreased risk of infection. Screening restricted to women who reported more than one sexual partner in the past year would have detected 44% of infections in women aged 16–25 years and would have required only 7% of women to be screened. The addition of those women aged 20 years and under would have required 27% of women to be screened and detection of 72% of infections.

Conclusions: Selective chlamydia screening of pregnant women based on risk factors can improve the yield from screening. However, the potential harm of missed infections among excluded women would need to be considered.

An improved purification procedure for cyclosporine synthetase

We have developed expedient and reliable methods to isolate cyclosporin synthetase for in vitro biosynthesis of cyclosporins. We have examined enzyme purification strategies suited to large-scale processing and present a chromatographic sequence that serves as a pilot model for industrial scale preparation of cyclosporin synthetase from cyclosporin producing fungi. A chromatographic sequence consisting of ammonium sulfate precipitation → gel filtration → hydrophobic interaction chromatography → anion exchange chromatography, yielded an electrophoretically homogeneous cyclosporin synthetase preparation (Coomassie G-250 brilliant blue staining). Furthermore, a native polyacrylamide gel electrophoresis system was developed for the isolation of active cyclosporin synthetase enzyme from crude extracts of cyclosporin producing fungi. The environmental factors affecting enzyme stability and the continuity of the in vitro cyclosporin biosynthetic reaction-temperature, pH, and substrate depletion were assessed and manageable conditions have been defined for sustainable cyclosporin biosynthesis with enzyme isolates. Cyclosporin synthetase exhibited an optimal temperature range of 24–29 °C and a pH optimum of 7.6. The native enzyme displayed a pI of 5.7, as determined by isoelectric focusing. The industrial implementation of an in vitro biosynthetic approach could potentially prove useful for the production of important therapeutic cyclosporins which occur as only minor fermentation by-products.

An improved method for the purification of rat liver-type fatty acid binding protein from Escherichia coli

We have developed expedient and reliable methods to isolate cyclosporin synthetase for in vitro biosynthesis of cyclosporins. We have examined enzyme purification strategies suited to large-scale processing and present a chromatographic sequence that serves as a pilot model for industrial scale preparation of cyclosporin synthetase from cyclosporin producing fungi. A chromatographic sequence consisting of ammonium sulfate precipitation → gel filtration → hydrophobic interaction chromatography → anion exchange chromatography, yielded an electrophoretically homogeneous cyclosporin synthetase preparation (Coomassie G-250 brilliant blue staining). Furthermore, a native polyacrylamide gel electrophoresis system was developed for the isolation of active cyclosporin synthetase enzyme from crude extracts of cyclosporin producing fungi. The environmental factors affecting enzyme stability and the continuity of the in vitro cyclosporin biosynthetic reaction-temperature, pH, and substrate depletion were assessed and manageable conditions have been defined for sustainable cyclosporin biosynthesis with enzyme isolates. Cyclosporin synthetase exhibited an optimal temperature range of 24–29 °C and a pH optimum of 7.6. The native enzyme displayed a pI of 5.7, as determined by isoelectric focusing. The industrial implementation of an in vitro biosynthetic approach could potentially prove useful for the production of important therapeutic cyclosporins which occur as only minor fermentation by-products.

Statphylococcus aureus bacteraemia : a major cause of mortaility in Australia and New Zealand

Objective : To document the types of, and mortality from, Staphylococcus aureus bacteraemia in Australia and New Zealand, and determine factors associated with mortality.

Design and setting : Prospective observational study in 27 independent or hospital pathology laboratories in Australia (24) and New Zealand (3), employing a web-based database to prospectively record demographic features, selected risk factors, principal antibiotic treatment and mortality data on all patients with positive blood cultures for S. aureus from June 2007 to May 2008.

Main outcome measure : 30-day all-cause mortality.

Results : 1994 episodes of S. aureus bacteraemia were identified, and complete 30-day follow-up data were available for 1865. Most episodes had their onset in the community (60.8%; 95% CI, 58.7%–63.0%). Methicillin-resistant S. aureus (MRSA) caused 450 episodes (24.1%; 95% CI, 22.2%–25.9%), and 123 of these (27.3%) had a susceptibility profile consistent with community-associated MRSA. All-cause mortality at 30 days was 20.6% (95% CI, 18.8%–22.5%). On univariate analysis, increased mortality was significantly associated with older age, European ethnicity, MRSA infection, infections not originating from a medical device, sepsis syndrome, pneumonia/empyema, and treatment with a glycopeptide or other non-β-lactam antibiotic. On multivariable analysis, independent predictors of mortality were age, sepsis syndrome, pneumonia/empyema, device-associated infection with a secondary focus, left-sided endocarditis, and treatment with a glycopeptide such as vancomycin, but not MRSA infection.

Conclusions : S. aureus bacteraemia is a common infection in both the community and hospitals in Australia and New Zealand, and is associated with appreciable mortality. Invasive MRSA infection may be more life-threatening, partly because of the inferior efficacy of the standard treatment, vancomycin. National web-based surveillance of S. aureus bacteraemia and its outcomes is not only important but also easily achievable.

Community onset staphylococcus aureus infections in Melbourne

Objective: To investigate the relative importance of methicillin resistant Staphylococcus aureus (MRSA) in the community in Melbourne by describing circulating S. aureus strains and infection characteristics.

Methods: Patients with any community-onset S. aureus infection were identified via clinical specimens submitted to a community-based pathology service in 2006. The referring doctors confirmed community onset and defined site and severity of each infection. Patient isolates were characterised by antibiotic resistance subtype and presence of the Panton-Valentine leukocidin gene (pvl).

Results: Between April and September 2006, 2,094 S. aureus isolates were processed. Of these, 133 (6.4%) were multiresistant MRSA (mMRSA) and 110 (5.3%) were resistant to less than 3 non-betalactam antibiotics (non-multiresistant MRSA or nmMRSA). We followed-up all nmMRSA (34) and mMRSA (15) confirmed community-onset infections, and a random subset of eligible patients with MSSA infections (57), for whom clinical data were available from referring doctors (82% response).

The majority of isolates were from skin infections (99/106), but drainage was performed in less than one third of cases (29/99). Antibiotics were prescribed for 89% (95%CI: 82, 94) of infections. The isolates were resistant to the prescribed antibiotic 100% of the time for mMRSA infections and 80% for nmMRSA. Those with infections caused by MRSA had on average one additional visit to their doctor compared with MSSA infections.

Ten nmMRSA clones were identified, including one new pvl positive nmMRSA. Of the 29 nmMRSA isolates, 14 were pvl positive (48%; 95%CIs: 30%, 66%) compared with 16% of MSSA and 0% mMRSA.

Patients with an infection caused by pvl positive strains (23) were younger ((mean age 23 years (95%CI: 16, 30) compared with the 55 years (95%CI: 50, 61)). Infection site also varied with presence of pvl; more pvl positive infections were found in the axilla (17.9% compared with 0%) and head and neck (35.7% compared with 8.2%), and less for the leg or foot (21.4% compared with 55.7%).

Conclusions: We estimate that 3.5% of community-onset S. aureus infections in Melbourne in 2006 were caused by MRSA, and 70 to 90% of patients with MRSA infections were treated initially with antibiotics to which their isolate was resistant. pvl positive isolates of S. aureus were associated with younger age and axillary or head and neck infections.

The ΔF508-CFTR mutation results in increased biofilm formation by Pseodomonas aeruginosa by increasing iron availability

Enhanced antibiotic resistance of Pseudomonas aeruginosa in the cystic fibrosis (CF) lung is thought to be due to the formation of biofilms. However, there is no information on the antibiotic resistance of P. aeruginosa biofilms grown on human airway epithelial cells or on the effects of airway cells on biofilm formation by P. aeruginosa. Thus we developed a coculture model and report that airway cells increase the resistance of P. aeruginosa to tobramycin (Tb) by >25-fold compared with P. aeruginosa grown on abiotic surfaces. Therefore, the concentration of Tb required to kill P. aeruginosa biofilms on airway cells is 10-fold higher than the concentration achievable in the lungs of CF patients. In addition, CF airway cells expressing ΔF508-CFTR significantly enhanced P. aeruginosa biofilm formation, and ΔF508 rescue with wild-type CFTR reduced biofilm formation. Iron (Fe) content of the airway in CF is elevated, and Fe is known to enhance P. aeruginosa growth. Thus we investigated whether enhanced biofilm formation on ΔF508-CFTR cells was due to increased Fe release by airway cells. We found that airway cells expressing ΔF508-CFTR released more Fe than cells rescued with WT-CFTR. Moreover, Fe chelation reduced biofilm formation on airway cells, whereas Fe supplementation enhanced biofilm formation on airway cells expressing WT-CFTR. These data demonstrate that human airway epithelial cells promote the formation of P. aeruginosa biofilms with a dramatically increased antibiotic resistance. The ΔF508-CFTR mutation enhances biofilm formation, in part, by increasing Fe release into the apical medium.

Self-assembly behavior of colistin and its prodrug colistin methanesulfonate : implications for solution stability and solubilization

Colistin is an amphiphilic antibiotic that has re-emerged into clinical use due to the increasing prevalence of difficult-to-treat Gram-negative infections. The existence of self-assembling colloids in solutions of colistin and its derivative prodrug, colistin methanesulfonate (CMS), was investigated. Colistin and CMS reduced the air−water interfacial tension, and dynamic light scattering (DLS) studies showed the existence of 2.07 ± 0.3 nm aggregates above 1.5 mM for colistin and of 1.98 ± 0.36 nm aggregates for CMS above 3.5 mM (mean ± SD). Above the respective critical micelle concentrations (CMC) the solubility of azithromycin, a hydrophobic antibiotic, increased approximately linearly with increasing surfactant concentration (5:1 mol ratio colistin:azithromycin), suggestive of hydrophobic domains within the micellar cores. Rapid conversion of CMS to colistin occurred below the CMC (60% over 48 h), while conversion above the CMC was less than 1%. The formation of colistin and CMS micelles demonstrated in this study is the proposed mechanism for solubilization of azithromycin and the concentration-dependent stability of CMS.

Early predictors of hospital admission in emergency department patients with chronic obstructive pulmonary disease

Background: Streamlining emergency department (ED) care of patients with chronic obstructive pulmonary disease (COPD) may be an important strategy in managing the increasing burden of this disease.

Study objectives: The aim of this study was to identify factors predictive of hospital admission in ED patients with COPD, specifically factors that can be used early in the ED episode of care.

Methods: Using retrospective regression analysis, case data from 321 randomly selected medical records from five Australian EDs were analysed. Patient characteristics, triage and ED system features, physiological status, and ED treatment during the first four hours of ED care were compared between discharged and admitted patients.

Results: Factors available on ED arrival associated with increased likelihood of admission were: age (OR = 1.04, p = 0.008) respiratory symptoms affecting activities of daily living (OR = 1.8, p = 0.043) and signs of respiratory dysfunction (OR = 2.5, p = 0.005). Factors available from the first four hours of ED care associated with increased likelihood of admission were: age (OR = 1.04, p = 0.021), oxygen use at four hours (OR = 3.5, p = 0.002) and IV antibiotic administration (OR = 2.6, p = 0.026). There were conflicting findings regarding the association between ambulance transport and admission.

Isolation of a novel Orientia species (O. chuto sp. nov.) from a patient infected in Dubai

In July 2006, an Australian tourist returning from Dubai, in the United Arab Emirates (UAE), developed acute scrub typhus. Her signs and symptoms included fever, myalgia, headache, rash, and eschar. Orientia tsutsugamushi serology demonstrated a 4-fold rise in antibody titers in paired serum collections (1:512 to 1:8,192), with the sera reacting strongest against the Gilliam strain antigen. An Orientia species was isolated by the in vitro culture of the patient's acute blood taken prior to antibiotic treatment. The gene sequencing of the 16S rRNA gene (rrs), partial 56-kDa gene, and the full open reading frame 47-kDa gene was performed, and comparisons of this new Orientia sp. isolate to previously characterized strains demonstrated significant sequence diversity. The closest homology to the rrs sequence of the new Orientia sp. isolate was with three strains of O. tsutsugamushi (Ikeda, Kato, and Karp), with a nucleotide sequence similarity of 98.5%. The closest homology to the 47-kDa gene sequence was with O. tsutsugamushi strain Gilliam, with a nucleotide similarity of 82.3%, while the closest homology to the 56-kDa gene sequence was with O. tsutsugamushi strain TA686, with a nucleotide similarity of 53.1%. The molecular divergence and geographically unique origin lead us to believe that this organism should be considered a novel species. Therefore, we have proposed the name “Orientia chuto,” and the prototype strain of this species is strain Dubai, named after the location in which the patient was infected.

Environmental impact assessment of the sewage outfall at Davis Station, East Antarctica

During the summer 2009/10, an environmental impact assessment of the sewage outfall was conducted at Davis Station, East Antarctica. An investigation of the nature and extent of impacts to the marine environment associated with current sewage treatment and effluent discharge practices included ecological surveys of macrobiological communities, physico-chemical analysis of sediments and receiving waters, microbiological analysis, and histopathological analysis of fish. Ecotoxicological testing using local invertebrates to determine effluent toxicity was interpreted alongside dispersal modelling data of the discharge plume to determine the potential extent of impacts and inform recommendations on the level of treatment and dilution of sewage required to minimise impacts. No evidence of impacts was detected on soft sediment infaunal or epifaunal communities, and only low levels of contamination and accumulation were found in sediments and waters in the immediate vicinity of the outfall and in the direction of primary current flow. In contrast, sterol biomarkers and faecal coliforms (E. coli) were detected in sediments collected adjacent to the outfall and in most water column samples. Marine invertebrates (Abatus and Laternula) also tested positive for E. coli and antibiotic resistance mechanisms were present in Laternula indicating the introduction and dispersal through the water column of foreign microbes and bacteria associated with human effluent. Fish (Trematomus bernacchii) close to the outfall showed significant histological alterations in all major tissues (liver, gill, gonad, muscle) resulting from exposure to sewage. Effluent was toxic to amphipods (Paramoera walkeri) and microgastropods (Skenella paludionoides), with reduced survival in concentrations as low as 3.125% over a 21d exposure period. Acute effects were also observed in both species following 24h exposure, with 100% mortality at the highest effluent concentrations tested (68%). The application of these results to support and guide decisions regarding the planned installation of new sewage treatment facilities at Davis will be discussed.

Why the tuberculosis incidence rate is not falling in New Zealand

Aims To assess the role of migration from high-incidence countries, HIV/AIDS infection, and prevalence of multi-drug resistant organisms as contributors to tuberculosis (TB) incidence in New Zealand (NZ) relative to ongoing local transmission and reactivation of disease.

Methods TB notification data and laboratory data for the period 1995 to 2004 and population data from the 1996 and 2001 Census were used to calculate incidence rates of TB by age and ethnicity, country of birth (distinguishing high and low -incidence countries), and interval between migration and onset of disease. Published reports of multi-drug-resistant TB for the period 1995 to 2004 were reviewed. Anonymous HIV surveillance data held by AIDS Epidemiology Group were matched with coded and anonymised TB surveillance data to measure the extent of HIV/AIDS coinfection in notified TB cases.

Results Migration of people from high-TB incidence countries is the main source of TB in NZ. Of those who develop TB, a quarter does so within a year of migration, and a quarter of this group (mainly refugees) probably enter the country with pre-existing disease. Rates of local TB transmission and reactivation of old disease are declining steadily for NZ-born populations, except for NZ-born Māori and Pacific people under 40. HIV/AIDS and multi-drug-resistant organisms are not significant contributors to TB incidence in NZ and there is no indication that their role is increasing.

Conclusion TB incidence is not decreasing in NZ mainly due to migration of TB infected people from high-incidence countries and subsequent development of active disease in some of them in NZ. This finding emphasises the importance of regional and global TB control initiatives. Refugees and migrants are not acting as an important source of TB for most NZ-born populations. Those caring for them should have a high level of clinical suspicion for TB.

Successful outcomes with oral fluoroquinolones combined with rifampicin in the treatment of Mycobacterium ulcerans : an observational cohort study

Background: The World Health Organization currently recommends combined streptomycin and rifampicin antibiotic treatment as first-line therapy for Mycobacterium ulcerans infections. Alternatives are needed when these are not tolerated or accepted by patients, contraindicated, or neither accessible nor affordable. Despite in vitro effectiveness, clinical evidence for fluoroquinolone antibiotic use against Mycobacterium ulcerans is lacking. We describe outcomes and tolerability of
fluoroquinolone-containing antibiotic regimens for Mycobacterium ulcerans in south-eastern Australia.

Methodology/Principal Findings: Analysis was performed of prospectively collected data including all primary Mycobacterium ulcerans infections treated at Barwon Health between 1998 and 2010. Medical treatment involved antibiotic use for more than 7 days; surgical treatment involved surgical excision of a lesion. Treatment success was defined as complete lesion healing without recurrence at 12 months follow-up. A complication was defined as an adverse event attributed to an antibiotic that required its cessation. A total of 133 patients with 137 lesions were studied. Median age was
62 years (range 3–94 years). 47 (34%) had surgical treatment alone, and 90 (66%) had combined surgical and medical treatment. Rifampicin and ciprofloxacin comprised 61% and rifampicin and clarithromycin 23% of first-line antibiotic
regimens. 13/47 (30%) treated with surgery alone failed treatment compared to 0/90 (0%) of those treated with combination medical and surgical treatment (p,0.0001). There was no difference in treatment success rate for antibiotic combinations containing a fluoroquinolone (61/61 cases; 100%) compared with those not containing a fluoroquinolone (29/29 cases; 100%). Complication rates were similar between ciprofloxacin and rifampicin (31%) and rifampicin and clarithromycin (33%) regimens (OR 0.89, 95% CI 0.27–2.99). Paradoxical reactions during treatment were observed in 8 (9%) of antibiotic treated cases.

Conclusions: Antibiotics combined with surgery may significantly increase treatment success for Mycobacterium ulcerans infections, and fluoroquinolone combined with rifampicin-containing antibiotic regimens can provide an effective and safe oral treatment option.

Community-onset Staphylococcus aureus infections presenting to general practices in South-eastern Australia

Community-acquired Staphylococcus aureus infections are a public health concern, yet little is known about infections that do not present to hospital. We identified community-onset S. aureus infections via specimens submitted to a community-based pathology service. Referring doctors confirmed eligibility and described infection site, severity and treatment. Isolates were characterized on antibiotic resistance, PFGE, MLST/SCCmec, and Panton–Valentine leukocidin (PVL), representing 106 community-onset infections; 34 non-multiresistant methicillin-resistant S. aureus (nmMRSA) (resistant to <3 non-β-lactam antibiotics), 15 multiply antibiotic-resistant MRSA (mMRSA) and 57 methicillin-sensitive S. aureus (MSSA). Most (93%) were skin and soft tissue infections. PVL genes were carried by 42% of nmMRSA isolates [95% confidence interval (CI) 26–61] and 15% of MSSA (95% CI 8–28). PVL was associated with infections of the trunk, head or neck (56·4% vs. 24·3%, P= 0·005) in younger patients (23 vs. 52 years, P< 0·001), and with boils or abscesses (OR 8·67, 95% CI 2·9–26·2), suggesting underlying differences in exposure and/or pathogenesis.

A case of Kingella kingae endocarditis complicated by native mitral valve rupture

We report a case of Kingella kingae endocarditis in a patient with a history of recent respiratory tract infection and dental extraction. This case is remarkable for embolic and vasculitic phenomena in association with a large valve vegetation and valve perforation. Kingella kingae is an organism known to cause endocarditis, however early major complications are uncommon. Our case of Kingella endocarditis behaved in a virulent fashion necessitating a combined approach of intravenous antibiotic therapy and a valve replacement. It highlights the importance of expedited investigation for endocarditis in patients with Kingella bacteraemia.

Clinical features and risk factors of oedematous Mycobacterium ulcerans lesions in an Australian population: beware cellulitis in an endemic area

Introduction
Oedematous lesions are a less common but more severe form of Mycobacterium ulcerans disease. Misdiagnosis as bacterial cellulitis can lead to delays in treatment. We report the first comprehensive descriptions of the clinical features and risk factors of patients with oedematous disease from the Bellarine Peninsula of south-eastern Victoria, Australia.

Methods
Data on all confirmed Mycobacterium ulcerans cases managed at Barwon Health, Victoria, were collected from 1/1/1998–31/12/2012. A multivariate logistic regression model was used to assess associations with oedematous forms of Mycobacterium ulcerans disease.

Results
Seventeen of 238 (7%) patients had oedematous Mycobacterium ulcerans lesions. Their median age was 70 years (IQR 17–82 years) and 71% were male. Twenty-one percent of lesions were WHO category one, 35% category two and 41% category three. 16 (94%) patients were initially diagnosed with cellulitis and received a median 14 days (IQR 9–17 days) of antibiotics and 65% required hospitalization prior to Mycobacterium ulcerans diagnosis. Fever was present in 50% and pain in 87% of patients. The WCC, neutrophil count and CRP were elevated in 54%, 62% and 75% of cases respectively. The median duration of antibiotic treatment was 84 days (IQR 67–96) and 94% of cases required surgical intervention. On multivariable analysis, there was an increased likelihood of a lesion being oedematous if on the hand (OR 85.62, 95% CI 13.69–535.70; P<0.001), elbow (OR 7.83, 95% CI 1.39–43.96; p<0.001) or ankle (OR 7.92, 95% CI 1.28–49.16; p<0.001), or if the patient had diabetes mellitus (OR 9.42, 95% CI 1.62–54.74; p = 0.02).

Conclusions
In an Australian population, oedematous Mycobacterium ulcerans lesions present with similar symptoms, signs and investigation results to, and are commonly mistakenly diagnosed for, bacterial limb cellulitis. There is an increased likelihood of oedematous lesions affecting the hand, elbow or ankle, and in patients with diabetes.