D. Marriott

Candidaemia in adult cancer patients: risks for fluconazole-resistant isolates and death

BACKGROUND Candidaemia in cancer patients is associated with increasing fluconazole resistance. Models for predicting such isolates and their clinical impact are required. METHODS Clinical, treatment and outcome data from a population-based candidaemia survey (2001-2004) were collected at 5 and 30 days after diagnosis. Speciation and antifungal susceptibility testing was performed. RESULTS There were 138 candidaemia episodes (33% Candida albicans) in adults with haematological malignancies and 150 (51% C. albicans) in adults with solid organ malignancies. Thirty-nine isolates had fluconazole MICs of >or=64 mg/L and 40 had MICs of 16-32 mg/L (predominantly Candida glabrata and Candida krusei). By multivariate analysis, triazole therapy, gastrointestinal tract (GIT) surgery in the 30 days before candidaemia and age >65 years were predictive of fluconazole-resistant candidaemia. Thirty day crude mortality was 40% in haematology patients and 45% in oncology patients. Fluconazole-resistant isolates were associated with increased risk of mortality by univariate (P = 0.04) and Kaplan-Meier survival analyses. By Cox proportional hazards modelling, the strongest predictors of mortality at onset of candidaemia were invasive ventilation, elevated creatinine, intensive care unit (ICU) admission and receipt of systemic triazoles or corticosteroids in the previous 30 days. Removal of a central venous access device (CVAD) at or within 5 days of onset was associated with decreased mortality. CONCLUSIONS Risk factors for fluconazole-resistant candidaemia in adults with cancer include fluconazole/triazole exposure and GIT surgery. ICU admission, invasive ventilation, renal impairment, age >65 years and prior exposure to corticosteroids and triazoles are risk factors for death. CVAD removal reduced mortality. These findings should be integrated into surveillance and treatment algorithms.

Methicillin-Resistant Staphylococcus aureus (MRSA) Detection: Comparison of Two Molecular Methods (IDI-MRSA PCR Assay and GenoType MRSA Direct PCR Assay) with Three Selective MRSA Agars (MRSA ID, MRSASelect, and CHROMagar MRSA) for Use with Infection-Control Swabs

ABSTRACT Methicillin-resistant Staphylococcus aureus (MRSA) is an increasing problem. Rapid detection of MRSA-colonized patients has the potential to limit spread of the organism. We evaluated the sensitivities and specificities of MRSA detection by two molecular methods (IDI-MRSA PCR assay and GenoType MRSA Direct PCR assay) and three selective MRSA agars (MRSA ID, MRSASelect, and CHROMagar MRSA), using 205 (101 nasal, 52 groin, and 52 axillary samples) samples from consecutive known MRSA-infected and/or -colonized patients. All detection methods had higher MRSA detection rates for nasal swabs than for axillary and groin swabs. Detection of MRSA by IDI-MRSA was the most sensitive method, independent of the site (94% for nasal samples, 80% for nonnasal samples, and 90% overall). The sensitivities of the GenoType MRSA Direct assay and the MRSA ID, MRSASelect, and CHROMagar MRSA agars with nasal swabs were 70%, 72%, 68%, and 75%, respectively. All detection methods had high specificities (95 to 99%), independent of the swab site. Extended incubation for a further 24 h with selective MRSA agars increased the detection of MRSA, with a corresponding decline in specificity secondary to a significant increase in false-positive results. There was a noticeable difference in test performance of the GenoType MRSA Direct assay in detection of MRSA (28/38 samples [74%]) compared with detection of nonmultiresistant MRSA (17/31 samples [55%]) (susceptible to two or more non-β-lactam antibiotics). This was not observed with selective MRSA agar plates or IDI-MRSA. Although it is more expensive, in addition to rapid turnaround times of 2 to 4 h, IDI-MRSA offers greater detection of MRSA colonization, independent of the swab site, than do conventional selective agars and GenoType MRSA Direct.

Voriconazole concentrations and outcome of invasive fungal infections

Twenty-five patients with proven or probable invasive fungal infections (IFIs) who experienced two or more episodes of voriconazole therapeutic drug monitoring (TDM) at a tertiary referral hospital were reviewed to explore the association between serum trough concentrations and outcomes of IFI. Microbiological and/or clinical success, in addition to IFI-related mortality, was assessed. We performed two separate analyses, one based on the initial trough voriconazole concentration at steady state, and the other on the median trough voriconazole concentration (derived from repeated TDM episodes) for each patient. Large interpatient and intrapatient variability of trough plasma voriconazole concentrations was observed, with no correlation between dose and concentration (r = 0.065). Classification and regression tree analysis revealed an association between IFI-related mortality and initial trough voriconazole concentrations, with patients more likely to die when their initial steady-state concentration was ≤0.35 mg/L (p 0.004; OR 11, 95% CI 2.9-41.2). Successful outcomes were more likely among patients with a median trough voriconazole concentration >2.2 mg/L (p 0.003; OR 2.7, 95% CI 1.4-5). Nineteen adverse events, with four severe events, were documented in 14 patients. Patients with severe adverse events had higher median voriconazole concentrations than the remaining cohort (2.38 mg/L vs. 1.30 mg/L; p <0.04). All adverse events resolved after cessation of voriconazole treatment. Our data suggest that voriconazole TDM is appropriate for all patients as soon as steady state is achieved. For non-responding patients with low trough concentrations, the association with IFI-related mortality indicates the need for dose adjustments to achieve and sustain voriconazole concentrations.

Candidaemia with uncommon Candida species: predisposing factors, outcome, antifungal susceptibility, and implications for management

The risk factors for and clinical features of bloodstream infection with uncommon Candida spp. (species other than C. albicans, C. glabrata, C. parapsilosis, C. tropicals and C. krusei) are incompletely defined. To identify clinical variables associated with these species that might guide management, 57 cases of candidaemia resulting from uncommon Candida spp. were analysed in comparison with 517 episodes of Candida albicans candidaemia (2001-2004). Infection with uncommon Candida spp. (5.3% of candidaemia cases), as compared with C. albicans candidaemia, was significantly more likely to be outpatient-acquired than inpatient-acquired (15 of 57 vs. 65 of 517 episodes, p 0.01). Prior exposure to fluconazole was uncommon (n=1). Candida dubliniensis was the commonest species (n=22, 39%), followed by Candida guilliermondii (n=11, 19%) and Candida lusitaniae (n=7, 12%).C. dubliniensis candidaemia was independently associated with recent intravenous drug use (p 0.01) and chronic liver disease (p 0.03), and infection with species other than C. dubliniensis was independently associated with age<65 years (p 0.02), male sex (p 0.03) and human immunodeficiency virus infection (p 0.05). Presence of sepsis at diagnosis and crude 30-day mortality rates were similar for C. dubliniensis-related, non-C. dubliniensis-related and C. albicans-related candidaemia. Haematological malignancy was the commonest predisposing factor in C. guilliermondii (n=3, 27%) and C. lusitaniae (n=3, 43%) candidaemia. The 30-day mortality rate of C. lusitaniae candidaemia was higher than the overall death rate for all uncommon Candida spp. (42.9% vs. 25%, p not significant). All isolates were susceptible to amphotericin B, voriconazole, posaconazole, and caspofungin; five strains (9%) had fluconazole MIC values of 16-32 mg/L. Candidaemia due to uncommon Candida spp. is emerging among hospital outpatients; certain clinical variables may assist in recognition of this entity.

Comparison of Stool Antigen Detection Kits to PCR for Diagnosis of Amebiasis

ABSTRACT The present study was conducted to compare two stool antigen detection kits with PCR for the diagnosis of Entamoeba histolytica infections by using fecal specimens submitted to the Department of Microbiology at St. Vincents Hospital, Sydney, and the Institute of Medical and Veterinary Science, Adelaide, Australia. A total of 279 stool samples containing the E complex (E. histolytica, Entamoeba dispar, and Entamoeba moshkovskii) were included in this study. The stool specimens were tested by using two commercially produced enzyme immunoassays (the Entamoeba CELISA PATH and TechLab E. histolytica II kits) to detect antigens of E. histolytica. DNA was extracted from all of the samples with a Qiagen DNA stool mini kit (Qiagen, Hilden, Germany), and a PCR targeting the small-subunit ribosomal DNA was performed on all of the samples. When PCR was used as a reference standard, the CELISA PATH kit showed 28% sensitivity and 100% specificity. The TechLab ELISA (enzyme-linked immunosorbent assay) kit did not prove to be useful in detecting E. histolytica, as it failed to identify any of the E. histolytica samples which were positive by PCR. With the TechLab kit, cross-reactivity was observed for three specimens, one of which was positive for both E. dispar and E. moshkovskii while the other two samples contained E. moshkovskii. Quantitative assessment of the PCR and ELISA results obtained showed that the ELISA kits were 1,000 to 10,000 times less sensitive, and our results show that the CELISA PATH kit and the TechLab ELISA are not useful for the detection of E. histolytica in stool samples from patients in geographical regions where this parasite is not endemic.

Managing antituberculosis drug therapy by therapeutic drug monitoring of rifampicin and isoniazid

Background:  Current therapeutic regimens with rifampicin and isoniazid have proven successful in treating tuberculosis, however, toxicity, therapeutic failure, relapse and multiple drug resistance are serious concerns. Optimizing drug dose using therapeutic drug monitoring (TDM) may be a better approach than administering therapy as a standard dose.

Invasive infections due to filamentous fungi other than Aspergillus: epidemiology and determinants of mortality

The epidemiology of invasive fungal disease (IFD) due to filamentous fungi other than Aspergillus may be changing. We analysed clinical, microbiological and outcome data in Australian patients to determine the predisposing factors and identify determinants of mortality. Proven and probable non-Aspergillus mould infections (defined according to modified European Organization for Research and Treatment of Cancer/Mycoses Study Group criteria) from 2004 to 2012 were evaluated in a multicentre study. Variables associated with infection and mortality were determined. Of 162 episodes of non-Aspergillus IFD, 145 (89.5%) were proven infections and 17 (10.5%) were probable infections. The pathogens included 29 fungal species/species complexes; mucormycetes (45.7%) and Scedosporium species (33.3%) were most common. The commonest comorbidities were haematological malignancies (HMs) (46.3%) diabetes mellitus (23.5%), and chronic pulmonary disease (16%); antecedent trauma was present in 21% of cases. Twenty-five (15.4%) patients had no immunocompromised status or comorbidity, and were more likely to have acquired infection following major trauma (p <0.01); 61 (37.7%) of cases affected patients without HMs or transplantation. Antifungal therapy was administered to 93.2% of patients (median 68 days, interquartile range 19-275), and adjunctive surgery was performed in 58.6%. The all-cause 90-day mortality was 44.4%; HMs and intensive-care admission were the strongest predictors of death (both p <0.001). Survival varied by fungal group, with the risk of death being significantly lower in patients with dematiaceous mould infections than in patients with other non-Aspergillus mould infections. Non-Aspergillus IFD affected diverse patient groups, including non-immunocompromised hosts and those outside traditional risk groups; therefore, definitions of IFD in these patients are required. Given the high mortality, increased recognition of infections and accurate identification of the causative agent are required.

Candidemia following solid organ transplantation in the era of antifungal prophylaxis: the Australian experience.

Abstract: Solid organ transplant (SOT) recipients have high rates of invasive fungal infections, with Candida species the most commonly isolated fungi. The aim of this study was to identify differences between incidence rates, risk factors, clinical presentations, and outcomes of candidemia in SOT recipients and non‐SOT patients. Data from the multicenter prospective Australian Candidaemia Study were examined. From August 2001 to July 2004, 24 episodes (2.2%; 24/1068) of candidemia were identified in SOT recipients. During this period, the numbers of transplanted organs included liver (n=455), kidney (n=1605), single lung (n=57), bilateral lung (n=183), heart and lung (n=18), heart (n=157), and pancreas (n=62). The overall annual estimated incidence of candidemia in SOT recipients was higher (3 per 1000 transplant admissions) than in non‐SOT patients (incidence 0.21 per 1000 admissions; P<0.001). The incidence and timing of candidemia post transplant was influenced by the transplanted organ type, with the majority of episodes (n=14, 54%) occurring >6 months after renal transplantation. Risk factors for candidemia in the month preceding diagnosis were similar to non‐SOT recipients except for corticosteroid therapy (P<0.001). Antifungal prophylaxis did not select for more resistant or non‐albicans Candida species in the SOT group. The 30‐day all‐cause mortality was similar to non‐SOT patients with candidemia and remains high at 21%. All deaths in SOT recipients occurred early (within 5 days of diagnosis), underlining a need for better diagnostic tests, targeted prevention, and early treatment strategies.

Post-transplant Pneumocystis jirovecii pneumonia--a re-emerged public health problem?

Pneumocystis jirovecii is a unicellular organism that in individuals with impaired immunity may cause pneumonia that can progress from minor illness to severe inflammatory pneumonia (PCP) with respiratory failure and death. Despite antimicrobial prophylaxis, which has reduced the incidence of PCP, clusters of late infections have been reported among kidney transplant recipients worldwide. A nosocomial PCP cluster was first recognized in 2010 at a Sydney hospital, but PCP clusters have since occurred in almost half of the renal transplant units on the eastern Australian seaboard, refocussing attention on optimal prophylaxis regimens and the likelihood of patient-to-patient transmission. A consensus meeting was conducted to derive the lessons from this experience for responding to PCP outbreaks. These included: (1) acting quickly--clusters of PCP in kidney transplant recipients with patient-to-patient transmission required transplant programs to act quickly to institute prophylactic and treatment measures; (2) instituting universal prophylaxis for all patients seen in the affected unit; (3) reducing patient-to-patient transmission via airborne droplets in the outpatient waiting areas; (4) examining the P. jirovecii genotypes. The meeting also considered recommendations for the duration of prophylaxis following de novo transplant and, for the individuals in whom long term prophylaxis is required, separating units with and without clusters of PCP.

MRSA detection: comparison of two molecular methods (BD GeneOhm® PCR assay and Easy-Plex) with two selective MRSA agars (MRSA-ID and Oxoid MRSA) for nasal swabs

Screening of patients is an important component for methicillin-resistant Staphylococcus aureus (MRSA) containment. The aim of this study was to determine the utility of molecular methods compared to selective agars for MRSA detection. Consecutive high risk patients (n = 200) were screened for nasal MRSA colonization using chromogenic selective agars (MRSA ID and CMRSA) as well as the BD GeneOhm MRSA (previously known as IDI-MRSA) and the Easy-Plex commercial real time PCR assays. The sensitivities of the molecular methods were similar to the BD GeneOhm MRSA (86%) and Easy-Plex (84%). The chromogenic agars, MRSA ID and CMRSA, showed sensitivities of 62% and 84%, respectively. Sensitivity was influenced by both the MRSA antibiograms and MRSA clonal type. The specificity was >98% in all methods except for the Easy-Plex assay (90%). Sensitivity of selective agars increased with 48 hours of incubation with a corresponding decrease in specificity. In conclusion, molecular detection methods for MRSA remain sensitive and rapid but are associated with greater expense.