Deborah Marriott

Epidemiology and Host- and Variety-Dependent Characteristics of Infection Due to Cryptococcus neoformans in Australia and New Zealand

A prospective population-based study was conducted in Australia and New Zealand during 1994-1997 to elucidate the epidemiology of cryptococcosis due to Cryptococcus neoformans var. neoformans (CNVN) and C. neoformans var. gattii (CNVG) and to relate clinical manifestations to host immune status and cryptococcal variety. The mean annual incidence per 10(6) population was 6.6 in Australia and 2.2 in New Zealand. Of 312 episodes, CNVN caused 265 (85%; 98% of the episodes in immunocompromised hosts) and CNVG caused 47 (15%; 44% of the episodes in immunocompetent hosts). The incidence of AIDS-associated cases in Australia declined annually (P<.001). Aborigines in rural or semirural locations (P<.001) and immunocompetent males (P<.001) were at increased risk of CNVG infection. Cryptococcomas in lung or brain were more common in immunocompetent hosts (P< or =.03) in whom there was an association only between lung cryptococcomas and CNVG. An AIDS-associated genetic profile of CNVN serotype A was confirmed by random amplification of polymorphic DNA analysis. Resistance to antifungal drugs was uncommon. The epidemiology of CNVN infection has changed substantially. Clinical manifestations of disease are influenced more strongly by host immune status than by cryptococcal variety.

Treatment of HIV-1-associated microsporidiosis and cryptosporidiosis with combination antiretroviral therapy

BACKGROUND Enterocytozoon bieneusi and Cryptosporidium parvum cause chronic antimicrobial-resistant gastrointestinal infections in HIV-1-infected individuals. HIV-1 reverse transcriptase inhibitors delay the onset of opportunistic infections, but are not known to reverse established infections. HIV-1 protease inhibitors are more effective across a broader range of HIV-1-infected immune cells. Combination antiretroviral therapy that includes a protease inhibitor could improve immunity to E bieneusi and C parvum. METHODS HIV-1 infected patients with chronic microsporidiosis (five), cryptosporidiosis (three), or dual infection (one), were treated with combination therapy that included at least one HIV-1 protease inhibitor. Outcome measures were symptoms, weight, use of antidiarrhoeal and antimicrobial drugs, T-lymphocyte subsets, HIV-1 viraemia, stool microscopy, and biopsy by endoscopy. FINDINGS All patients had complete clinical responses, gained a median 15 kg in weight, and ceased all antidiarrhoeal and antimicrobial therapies. Biliary cryptosporidiosis responded in both affected patients. Neither pathogen was detected in follow-up stool microscopy (eight of eight patients) or in biopsy samples by endoscopy (five of five). Intestinal architecture returned to normal in three patients. There was a dense CD8 lymphocyte and macrophage infiltrate and staining of intraepithelial E bieneusi with interferon-gamma before and after treatment, but little staining for CD4 or B lymphocytes, interleukin 10, or HIV-1 gp41. Five patients remained symptom-free after a median 13 months follow-up. Four patients had recurrent diarrhoea at 7-13 months (one with positive stool microscopy), associated with declining CD4 counts. INTERPRETATION Combination antiretroviral therapy that includes a protease inhibitor can restore immunity to E bieneusi or C parvum in HIV-1 infected individuals, and result in complete clinical, microbiological, and histological responses. The persistent CD8 cell and macrophage infiltrate, and the rapid time to relapse in patients with declining CD4 lymphocyte counts, suggest that neither infection was eradicated.

Laboratory Diagnostic Techniques for Entamoeba Species

SUMMARY The genus Entamoeba contains many species, six of which (Entamoeba histolytica, Entamoeba dispar, Entamoeba moshkovskii, Entamoeba polecki, Entamoeba coli, and Entamoeba hartmanni) reside in the human intestinal lumen. Entamoeba histolytica is the causative agent of amebiasis and is considered a leading parasitic cause of death worldwide in humans. Although recent studies highlight the recovery of E. dispar and E. moshkovskii from patients with gastrointestinal symptoms, there is still no convincing evidence of a causal link between the presence of these two species and the symptoms of the host. New approaches to the identification of E. histolytica are based on detection of E. histolytica-specific antigen and DNA in stool and other clinical samples. Several molecular diagnostic tests, including conventional and real-time PCR, have been developed for the detection and differentiation of E. histolytica, E. dispar, and E. moshkovskii in clinical samples. The purpose of this review is to discuss different methods that exist for the identification of E. histolytica, E. dispar, and E. moshkovskii which are available to the clinical diagnostic laboratory. To address the need for a specific diagnostic test for amebiasis, a substantial amount of work has been carried out over the last decade in different parts of the world. The molecular diagnostic tests are increasingly being used for both clinical and research purposes. In order to minimize undue treatment of individuals infected with other species of Entamoeba such as E. dispar and E. moshkovskii, efforts have been made for specific diagnosis of E. histolytica infection and not to treat based simply on the microscopic examination of Entamoeba species in the stool. The incorporation of many new technologies into the diagnostic laboratory will lead to a better understanding of the public health problem and measures to control the disease.

Low-Dose Trimethoprim-Sulfamethoxazole Prophylaxis for Toxoplasmic Encephalitis in Patients with AIDS

OBJECTIVE To determine the efficacy of low-dose trimethoprim-sulfamethoxazole (trimethoprim, 160 mg plus sulfamethoxazole, 800 mg; one tablet twice daily, 2 days per week) as primary prophylaxis against toxoplasmic encephalitis in patients with human immunodeficiency virus (HIV) infection and previous Pneumocystis carinii pneumonia. DESIGN A retrospective study. SETTING Tertiary referral teaching hospital. PATIENTS During a 3-year period after primary episodes of P. carinii pneumonia, 60 patients received trimethoprim-sulfamethoxazole, and 95 patients received pentamidine (aerosolized in 78 patients and intravenous in 17 patients) as secondary prophylaxis. RESULTS No patient in the trimethoprim-sulfamethoxazole group and no patient seronegative for Toxoplasma gondii developed toxoplasmic encephalitis, compared with 12 of 36 (33%; 95% Cl, 19% to 51%) seropositive patients in the pentamidine group (trimethoprim-sulfamethoxazole compared with pentamidine, P = 0.008). A significant difference was seen in the time to development of toxoplasmic encephalitis between the trimethoprim-sulfamethoxazole group (no case at 1153 days) and the pentamidine group (median time, 460 days) (P = 0.004). Neither the CD4+ lymphocyte count at the start of prophylaxis nor zidovudine therapy during the period of prophylaxis influenced the rate of toxoplasmic encephalitis in any group. CONCLUSIONS Low-dose trimethoprim-sulfamethoxazole (four tablets per week) appears to be effective prophylaxis against toxoplasmic encephalitis in HIV-infected patients with previous P. carinii pneumonia. A prospective, randomized, controlled study is needed to further evaluate these findings.

Not Just Little Adults: Candidemia Epidemiology, Molecular Characterization, and Antifungal Susceptibility in Neonatal and Pediatric Patients

OBJECTIVE. The purpose of this work was to identify differences in incidence, risk factors, microbiology, treatment, and clinical outcome of candidemia in neonates, children, and adults that might impact on management. PATIENTS AND METHODS. Cases of candidemia in Australia were identified prospectively by blood culture surveillance over 3 years. Episodes of candidemia in neonatal, pediatric, and adult age groups were analyzed and compared. RESULTS. Of 1005 incident cases, 33 occurred in neonates, 110 in children, and 862 in adults. The respective annual age-specific incidences were 4.4, 0.9, and 1.8 per 100 000 population. Prematurity and ICU admission were major risk factors in neonates. Hematologic malignancy and neutropenia were significantly more frequent in children than in neonates and adults. Diabetes, renal disease, hemodialysis, and recent surgery were more common in adults. Candidemia was attributed to a vascular access device in 58% of neonates, 70% of children, and 44% of adults. Candida albicans caused ∼48% of cases in all of the age groups. Candida parapsilosis was significantly more common in neonates and children (42% and 38% vs 15%). Candida glabrata was infrequent in neonates and children (9% and 3% vs 17%). Significantly more isolates from children were susceptible to fluconazole compared with those from adults (95% vs 75%). Fluconazole-resistant candidal isolates were infrequent in all of the age groups. Neonates and children were more likely to receive amphotericin B compared with adults. Adults were more likely to receive fluconazole. Survival rates at 30 days were 78% in neonates, 90% in children, and 70% in adults. CONCLUSIONS. This study identifies significant differences in candidemia in neonates, children, and adults. Neonatologists and pediatricians must consider age-specific differences when interpreting adult studies and developing treatment and prevention guidelines.

Active surveillance for candidemia, Australia.

This infection has a high death rate and is predominantly associated with healthcare.

Clinical Significance of Enteric Protozoa in the Immunosuppressed Human Population

SUMMARY Globally, the number of immunosuppressed people increases each year, with the human immunodeficiency virus (HIV) pandemic continuing to spread unabated in many parts of the world. Immunosuppression may also occur in malnourished persons, patients undergoing chemotherapy for malignancy, and those receiving immunosuppressive therapy. Components of the immune system can be functionally or genetically abnormal as a result of acquired (e.g., caused by HIV infection, lymphoma, or high-dose steroids or other immunosuppressive medications) or congenital illnesses, with more than 120 congenital immunodeficiencies described to date that either affect humoral immunity or compromise T-cell function. All individuals affected by immunosuppression are at risk of infection by opportunistic parasites (such as the microsporidia) as well as those more commonly associated with gastrointestinal disease (such as Giardia). The outcome of infection by enteric protozoan parasites is dependent on absolute CD4+ cell counts, with lower counts being associated with more severe disease, more atypical disease, and a greater risk of disseminated disease. This review summarizes our current state of knowledge on the significance of enteric parasitic protozoa as a cause of disease in immunosuppressed persons and also provides guidance on recent advances in diagnosis and therapy for the control of these important parasites.

Candidemia in nonneutropenic critically ill patients: risk factors for non-albicans Candida spp.

Objective:The objective of this study was to determine the clinical features associated with candidemia caused by non-albicans Candida spp. and with potentially fluconazole-resistant Candida spp. (C. glabrata and C. krusei) among candidemic intensive care unit patients. Design:The authors conducted a nationwide prospective cohort study. Setting:The study was conducted in Australian intensive care units. Patients:All patients with intensive care unit-acquired candidemia over a 3-yr period were included in the study. Measurements:Clinical risk factors occurring up to 30 days before candidemia, Candida spp. associated with candidemia, and outcomes were determined. Risk factors associated with either non-albicans Candida spp. or with potentially fluconazole-resistant Candida spp. (C. glabrata or C. krusei) were assessed using multivariate logistic regression. Main Results:Among 179 episodes of intensive care unit-acquired candidemia, C. albicans accounted for 62%, C. glabrata 18%, C. krusei 4%, and other Candida spp. 16%. Independently significant variables associated with non-albicans Candida bloodstream infection included recent prior gastrointestinal surgery (adjusted odds ratio, 2.87; 95% confidence interval, 1.68–4.91) and recent prior systemic antifungal exposure (4.6; 1.36–15.53). Those associated with potentially fluconazole-resistant candidemia included recent prior gastrointestinal surgery (3.31; 1.79–6.11) and recent prior fluconazole exposure (5.47; 1.23–24.32). No significant differences in outcomes were demonstrated for non-albicans or potentially fluconazole-resistant candidemia. Conclusions:Among candidemic intensive care unit patients, prior gastrointestinal surgery and systemic antifungal exposure were significantly associated with both a non-albicans Candida spp. and a potentially fluconazole-resistant Candida spp. LEARNING OBJECTIVESOn completion of this article, the reader should be able to:List clinical features discriminating between candidemia caused by C. albicans and those caused by other species.Describe predisposing factors that help discriminate between candidemia which are potentially fluconazole-resistant.Use this information in a clinical setting.Dr. Playford has disclosed that he was a consultant/advisor for Pfizer and Merck; was on the advisory board for Schering-Plough; and is a recipient of grant/research funds from Pfizer and Merck. Dr. Marriott has disclosed that she was/is a recipient of grant/research funds from Pfizer; was/is a consultant/advisor for Merck, Sharpe & Dohme and Sanofi-Pasteur; and was/is on the advisory board for Roche. Dr. Nguyen has disclosed that he has no financial relationships with or interests in any commercial companies pertaining to this educational activity. Dr. Chen has disclosed that she was a recipient of grant/research funds from Pfizer; is a recipient of grant/research funds from Gilead Sciences, Inc.; and is on the advisory board for Gilead Sciences, Inc. and Pfizer Australia. Dr. Ellis has disclosed that he was/is a recipient of grant/research funds from Pfizer Australia, Merck, Sharpe & Dohme Australia, Gilead Sciences Australia, and Schering-Plough Australia; was/is a consultant/advisor for Pfizer Australia, Merck, Sharpe & Dohme Australia, Gilead Sciences Australia, and Schering-Plough Australia; and was/is on the speakers bureau for Pfizer Australia, Merck, Sharpe & Dohme Australia, Gilead Sciences Australia, and Schering-Plough Australia. Dr. Slavin has disclosed that she was/is a recipient of grant/research funds from Pfizer Inc., Gilead Sciences, Schering-Plough, and Merck and Co.; and was/is on the advisory board for Pfizer Inc., Gilead Sciences, Schering-Plough, and Merck and Co. Dr. Sorrell has disclosed that she was/is a recipient of grant/research funds from Merck, Sharpe & Dohme Australia, Pfizer, and Gilead; and was/is a consultant/advisor for Pfizer, Merck, Gilead, and Schering-Plough.All faculty and staff in a position to control the content of this CME activity have disclosed that they have no financial relationship with, or financial interests in, any commercial companies pertaining to this educational activity.Lippincott CME Institute, Inc., has identified and resolved all faculty conflicts of interest regarding this educational activity.Visit the Critical Care Medicine Web Site (www.ccmjournal.org) for information on obtaining continuing medical education credit.

Posaconazole exposure-response relationship: evaluating the utility of therapeutic drug monitoring.

ABSTRACT Posaconazole has become an important part of the antifungal armamentarium in the prophylaxis and salvage treatment of invasive fungal infections (IFIs). Structurally related to itraconazole, posaconazole displays low oral bioavailability due to poor solubility, with significant drug interactions and gastrointestinal disease also contributing to the generally low posaconazole plasma concentrations observed in patients. While therapeutic drug monitoring (TDM) of plasma concentrations is widely accepted for other triazole antifungal agents such as voriconazole, the utility of TDM for posaconazole is controversial due to debate over the relationship between posaconazole exposure in plasma and clinical response to therapy. This review examines the available evidence for a relationship between plasma concentration and clinical efficacy for posaconazole, as well as evaluating the utility of TDM and providing provisional target concentrations for posaconazole therapy. Increasing evidence supports an exposure-response relationship for plasma posaconazole concentrations for prophylaxis and treatment of IFIs; a clear relationship has not been identified between posaconazole concentration and toxicity. Intracellular and intrapulmonary concentrations have been studied for posaconazole but have not been correlated to clinical outcomes. In view of the high mortality and cost associated with the treatment of IFIs, increasing evidence of an exposure-response relationship for posaconazole efficacy in the prevention and treatment of IFIs, and the common finding of low posaconazole concentrations in patients, TDM for posaconazole is likely to be of significant clinical utility. In patients with subtherapeutic posaconazole concentrations, increased dose frequency, administration with high-fat meals, and withdrawal of interacting medications from therapy are useful strategies to improve systemic absorption.

Evaluation of Multiplex Tandem Real-Time PCR for Detection of Cryptosporidium spp., Dientamoeba fragilis, Entamoeba histolytica, and Giardia intestinalis in Clinical Stool Samples

ABSTRACT The aim of this study was to describe the first development and evaluation of a multiplex tandem PCR (MT-PCR) assay for the detection and identification of 4 common pathogenic protozoan parasites, Cryptosporidium spp., Dientamoeba fragilis, Entamoeba histolytica, and Giardia intestinalis, from human clinical samples. A total of 472 fecal samples submitted to the Department of Microbiology at St. Vincents Hospital were included in the study. The MT-PCR assay was compared to four real-time PCR (RT-PCR) assays and microscopy by a traditional modified iron hematoxylin stain. The MT-PCR detected 28 G. intestinalis, 26 D. fragilis, 11 E. histolytica, and 9 Cryptosporidium sp. isolates. Detection and identification of the fecal protozoa by MT-PCR demonstrated 100% correlation with the RT-PCR results, and compared to RT-PCR, MT-PCR exhibited 100% sensitivity and specificity, while traditional microscopy of stained fixed fecal smears exhibited sensitivities and specificities of 56% and 100% for Cryptosporidium spp., 38% and 99% for D. fragilis, 47% and 97% for E. histolytica, and 50% and 100% for G. intestinalis. No cross-reactivity was detected in 100 stool samples containing various other bacterial, viral, and protozoan species. The MT-PCR assay was able to provide rapid, sensitive, and specific simultaneous detection and identification of the four most important diarrhea-causing protozoan parasites that infect humans. This study also highlights the lack of sensitivity demonstrated by microscopy, and thus, molecular methods such as MT-PCR must be considered the diagnostic methods of choice for enteric protozoan parasites.