Miliary pulmonary cryptococcosis

A 32-year-old HIV positive male presents with fevers and a non-productive cough. Initial X-ray and subsequent computerised tomography of the chest shows a bilateral miliary pattern of pulmonary infiltration highly suggestive of disseminated tuberculosis. However subsequent results were consistent with disseminated cryptococcosis, including pulmonary involvement, with cryptococcus identified on transbronchial tissue biopsy, and on blood and cerebrospinal fluid cultures.

Imaging features of pulmonary cryptococcosis are generally of well-defined pleural-based nodules and less commonly alveolar infiltrates, lymphadenopathy, pleural effusions or cavitating lesions. Miliary pulmonary infiltrates are an exceptionally rare presentation.

Treatment failure in patients with chronic Blastocystis infection

This article reports long-term infection and treatment failure in 18 symptomatic individuals infected with Blastocystis spp. Patients were initially treated with either metronidazole, iodoquinol or triple combination therapy consisting of nitazoxanide, furazolidone and secnidazole. Following treatment, resolution of clinical symptoms did not occur and follow-up testing revealed ongoing infection with the same subtype. Patients then underwent secondary treatment with a variety of antimicrobial agents but remained symptomatic with Blastocystis spp. still present in faeces. Sequencing of the SSU rDNA was completed on all isolates and four subtypes were identified in this group: ST1, ST3, ST4 and ST5. This study highlights the lack of efficacy of several commonly used antimicrobial regimens in the treatment of Blastocystis and the chronic nature of some infections. It also demonstrates the need for further research into treatment options for Blastocystis infection.

Antifungal therapy and management of complications of cryptococcosis due to Cryptococcus gattii

BACKGROUND

We describe antifungal therapy and management of complications due to Cryptococcus gattii infection in 86 Australian patients followed for at least 12 months.

METHODS

Patient data from culture-confirmed cases (2000-2007) were recorded at diagnosis, 6 weeks, 6 months, and 12 months. Clinical, laboratory, and treatment variables associated with raised intracranial pressure (ICP) and immune reconstitution inflammatory syndrome (IRIS) were determined.

RESULTS

Seven of 10 patients with lung infection received amphotericin B (AMB) induction therapy (6 with 5-flucytosine [5-FC] for a median of 2 weeks); median duration of therapy including azole eradication therapy was 41 weeks, with a complete/partial clinical response in 78%. For neurologic disease, 88% of patients received AMB, 78% with 5-FC, for a median of 6 weeks. The median total course was 18 months. Nine patients receiving fluconazole induction therapy were reinduced with AMB plus 5-FC for clinical failure. Raised ICP (31 patients) was associated with initial abnormal neurology, and neurologic sequelae and/or death at 12 months (both P = .02); cerebrospinal fluid drains/shunts were placed in 58% of patients and in 64% of 22 patients with hydrocephalus. IRIS developed 2-12 months after starting antifungals in 8 patients, who presented with new/enlarging brain lesions. Risk factors included female sex, brain involvement at presentation, and higher median CD4 counts (all P < .05); corticosteroids reduced cryptococcoma-associated edema.

CONCLUSIONS

Induction AMB plus 5-FC is indicated for C. gattii neurologic cryptococcosis (6 weeks) and when localized to lung (2 weeks). Shunting was often required to control raised ICP. IRIS presents with cerebral manifestations.

Current treatment options for Dientamoeba fragilis infections

Dientamoeba fragilis belongs to the trichomonad group of protozoan parasites and it has been implicated as a cause of gastrointestinal disease with world-wide prevalences ranging from 0.5% to 16%. The majority of patients with dientamoebiasis present with gastrointestinal complaints. Chronic symptoms are common with up to a third of patients exhibiting persistent diarrhoea. Numerous studies have successfully demonstrated parasite clearance, coupled with complete resolution of clinical symptoms following treatment with various antiparasitic compounds. Treatments reported to be successful for dientamoebiasis include carbarsone, diphetarsone, tetracyclines, paromomycin, erythromycin, hydroxyquinolines and the 5-nitroimidazoles, including metronidazole, secnidazole, tinidazole and ornidazole. It is of note that most current treatment data is based only on small number of case reports. No large scale double blind randomised placebo controlled trials testing the efficacy of antimicrobial agents against D. fragilis has been undertaken highlighting the need for further study. In addition there is very little in vitro susceptibility data available for the organism making some current treatment options questionable. The aim of this review is to critically discuss all treatment options currently available for dientamoebiasis.

Clinical manifestations of Cryptococcus gattii infection: determinants of neurological sequelae and death

BACKGROUND

Longer-term morbidity and outcomes of Cryptococcus gattii infection are not described. We analyzed clinical, microbiological, and outcome data in Australian patients followed for 12 months, to identify prognostic determinants.

METHODS

Culture-confirmed C. gattii cases from 2000 to 2007 were retrospectively evaluated. Clinical, microbiological, radiological, and outcome data were recorded at diagnosis and at 6 weeks, 6 months, and 12 months. Clinical and laboratory variables associated with mortality and with death and/or neurological sequelae were determined.

RESULTS

Annual C. gattii infection incidence was 0.61 per 10(6) population. Sixty-two of 86 (72%) patients had no immunocompromise; 6 of 24 immunocompromised hosts had idiopathic CD4 lymphopenia, and 1 had human immunodeficiency virus/AIDS. Clinical and microbiological characteristics of infection were similar in immunocompromised and healthy hosts. Isolated lung, combined lung and central nervous system (CNS), and CNS only disease was reported in 12%, 51% and 34% of the cases, respectively. Complications in CNS disease included raised intracranial pressure (42%), hydrocephalus (30%), neurological deficits (27%; 6% developed during therapy) and immune reconstitutionlike syndrome (11%). Geometric mean serum cryptococcal antigen (CRAG) titers in CNS disease were 563.9 (vs 149.3 in isolated lung infection). Patient immunocompromise was associated with increased mortality risk. An initial cerebrospinal fluid CRAG titer of ≥256 predicted death and/or neurological sequelae (P = .05).

CONCLUSIONS

Neurological C. gattii disease predominates in the Australian endemic setting. Lumbar puncture and cerebral imaging, especially if serum CRAG titers are ≥512, are essential. Long-term follow up is required to detect late neurological complications. Immune system evaluation is important because host immunocompromise is associated with reduced survival.

Detection and transmission of Dientamoeba fragilis from environmental and household samples

Dientamoeba fragilis is a commonly occurring pathogenic protozoan often detected at higher rates in stool samples than Giardia intestinalis. However, little is known about its life cycle and mode of transmission. A total of 210 environmental and household samples were examined for the presence of D. fragilis by culture and polymerase chain reaction. Of 100 environmental samples, D. fragilis was detected only in untreated sewage. In the household samples D. fragilis was detected in 30% of household contacts tested and was not detected in any domestic pets. This study provides evidence that environmental transmission of D. fragilis is unlikely and that pets played no role in transmission of the disease in this study. Direct transmission from infected persons is the most likely mode of transmission for D. fragilis. The study also highlights the need for household contacts to be screened, given the propensity of close contacts to become infected with the organism.

Identification of novel hybrids between Cryptococcus neoformans var. grubii VNI and Cryptococcus gattii VGII

Cryptococcus neoformans and Cryptococcus gattii are pathogenic yeasts causing meningoencephalitis in immunocompromised and immunocompetent hosts. The fungus is typically haploid, and sexual reproduction occurs normally between individuals with opposite mating types, α and a. C. neoformans var. grubii (serotype A) is comprised of molecular types VNI, VNII, and VNB, and C. neoformans var. neoformans (serotype D) contains the molecular type VNIV. Additionally, diploid or aneuploid AD hybrids (VNIII) have been reported. C. gattii contains the molecular types VGI, VGII, VGIII, and VGIV, which encompass both serotypes B and C. To identify possible hybrid strains, URA5-RFLP analysis was performed on 350 globally obtained clinical, environmental, and veterinary isolates. Four clinical isolates from cerebrospinal fluid showed combination patterns of C. neoformans var. grubii and C. gattii: Brazil (n = 2), Colombia (n = 1), and India (n = 1). These strains were monokaryotic and diploid or aneuploid. M13 PCR fingerprinting showed that they contained fragments of both proposed parental groups. Luminex IGS genotyping identified these isolates as hybrids with two different molecular type combinations: three VNI/VGII and one VNI/VGI. Blue color development on CGB agar was delayed in three isolates and absent in one. C. gattii-specific PCR confirmed the presence of C. gattii in the hybrids. CAP59 allele-specific PCR revealed that all the hybrids contained both serotype A and B alleles. Determination of mating-type allelic patterns by PCR revealed that the isolates were αA aB. This is the first study discovering novel natural hybrids between C. neoformans molecular type VNI and C. gattii molecular type VGII.

A review of Dientamoeba fragilis carriage in humans: several reasons why this organism should be considered in the diagnosis of gastrointestinal illness

Dientamoeba fragilis is a protozoan that inhabits the human gut. It is approximately 100 years since Dientamoeba's discovery and first description when it was described as a rare and harmless commensal. Since then it has struggled to gain recognition as a pathogen despite the evidence supporting its pathogenicity. Dientamoeba remains neglected, probably due to the misconceptions that it is uncommon and non-pathogenic. Usually, carriage of Dientamoeba is associated with symptoms such as abdominal pain and diarrhea. Moreover, antimicrobial therapy followed by resolution of symptoms coincides with the eradication of Dientamoeba. This manuscript reviews the scientific literature relating to Dientamoeba's prevalence and pathogenicity. While much of the evidence supporting its pathogenicity is only circumstantial, it is apparent that most researchers agree that Dientamoeba is pathogenic. Therefore, in symptomatic patients who harbor Dientamoeba and no other pathogen, Dientamoeba should be considered as the etiological agent and treated as such.

Seroprevalence of Entamoeba histolytica infection among men who have sex with men in Sydney, Australia

A retrospective analysis was undertaken to determine the seroprevalence of Entamoeba histolytica infection in Sydney, Australia. Using an enzyme-linked immunosorbent assay, 429 high risk human immunodeficiency virus (HIV)-infected men who have sex with men (MSM), 446 low risk HIV-uninfected MSM, and 456 HIV-uninfected controls were assessed. Seroprevalence rates were 5.13% for the high risk HIV-infected MSM group, 0.22% for the low risk HIV-uninfected MSM group, and 0.44% for the control group. We found that high risk HIV-infected MSM have a significantly greater seroprevalence of E. histolytica with a relative risk of 22.87, when compared with low risk HIV-uninfected MSM and 11.69 when compared with controls. These findings show that in Sydney, sexually active HIV-infected MSM are at greater risk of developing amoebic disease caused by E. histolytica than HIV-uninfected MSM and the general population.

Importance of nonenteric protozoan infections in immunocompromised people

There are many neglected nonenteric protozoa able to cause serious morbidity and mortality in humans, particularly in the developing world. Diseases caused by certain protozoa are often more severe in the presence of HIV. While information regarding neglected tropical diseases caused by trypanosomatids and Plasmodium is abundant, these protozoa are often not a first consideration in Western countries where they are not endemic. As such, diagnostics may not be available in these regions. Due to global travel and immigration, this has become an increasing problem. Inversely, in certain parts of the world (particularly sub-Saharan Africa), the HIV problem is so severe that diseases like microsporidiosis and toxoplasmosis are common. In Western countries, due to the availability of highly active antiretroviral therapy (HAART), these diseases are infrequently encountered. While free-living amoebae are rarely encountered in a clinical setting, when infections do occur, they are often fatal. Rapid diagnosis and treatment are essential to the survival of patients infected with these organisms. This paper reviews information on the diagnosis and treatment of nonenteric protozoal diseases in immunocompromised people, with a focus on patients infected with HIV. The nonenteric microsporidia, some trypanosomatids, Toxoplasma spp., Neospora spp., some free-living amoebae, Plasmodium spp., and Babesia spp. are discussed.

A review of the clinical presentation of dientamoebiasis

Among 750 symptomatic and asymptomatic patients, Dientamoeba fragilis was detected at a prevalence of 5.2% and more common than Giardia intestinalis. Most infected patients presented with diarrhea and abdominal pain with symptoms greater than 2 weeks duration being common. Bacterial and viral causes of infection were excluded by routine microbiological techniques. Treatment of D. fragilis infection with either iodoquinol, paromomycin, or combination therapy resulted in the eradication of the parasite and complete resolution of symptoms. Treatment failure/relapses were associated only with the use of metronidazole. Nineteen patients were examined for pin worm, no Enterobius vermicularis, a proposed vector of transmission, were detected. Intermittent shedding of D. fragilis was found to be highly variable. These studies confirm the pathogenic nature of D. fragilis and we recommend laboratories routinely test for the organism.

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.

Laryngeal cryptococcosis: Clinical presentation and treatment of a rare cause of hoarseness

Objective: Laryngeal cryptococcosis is rare, with few reported cases in the literature. We present current investigation and treatment recommendations for this disease.

Study Design: A structured literature review; additional cases and expert opinion are presented.

Results: Localized laryngeal cryptococcal infection most commonly presents with persisting hoarseness. Clinical suspicion of the disease is required for accurate diagnosis, with treatment based on the patient's immune status. Early microbiological advice and adequate follow-up is recommended to ensure disease resolution.

Conclusion: Isolated laryngeal cryptococcosis is a rare presentation of fungal infection. It is easily treated and should be considered in the differential diagnosis of patients with persisting hoarseness.

Repeated Dientamoeba fragilis infections: a case report of two families from Sydney, Australia

We report cases of two unrelated families who both presented with recurrent Dienta-moeba fragilis infections. Subsequent antimicrobial therapy resulted in the clearance of D. fragilis and total resolution of gastrointestinal symptoms in both families. This report highlights the potentially recurrent nature of D. fragilis infections and the need for laboratories to routinely test for this organism.

Clinical significance of enteric protozoa in the immunosuppressed human population

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.

Repeated Dientamoeba fragilis infections: a case report of two families from Sydney, Australia

We report cases of two unrelated families who both presented with recurrent Dientamoeba fragilis infections. Subsequent antimicrobial therapy resulted in the clearance of D. fragilis and total resolution of gastrointestinal symptoms in both families. This report highlights the potentially recurrent nature of D. fragilis infections and the need for laboratories to routinely test for this organism.

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.

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 approximately 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.

Limited genetic diversity among genotypes of Enterocytozoon bieneusi strains isolated from HIV-infected patients from Sydney, Australia

Microsporidia are intracellular parasites, with over 1200 species belonging to 143 genera described to date. They are opportunistic pathogens in humans and can cause chronic diarrhoea in immunosuppressed patients. Both Enterocytozoon bieneusi and Encephalitozoon intestinalis cause intestinal disease, with Enterocytozoon bieneusi more commonly identified in patients with human immunodeficiency virus (HIV) infection. In this study, intestinal microsporidial clinical isolates from patients in Sydney, Australia, were genotyped. All specimens were from HIV-infected men with low CD4(+) T-cell counts (<100 cells mm(-3)). Genotyping of the internal transcribed spacer regions of the rRNA gene showed the presence of only one genotype, the anthroponotic Enterocytozoon bieneusi genotype B strain. This study thus highlighted the limited genetic diversity among Australian Enterocytozoon bieneusi isolates, and it is hypothesized that, due to the reduced incidence of microsporidia and the subsequent reduction in the human reservoir of the anthroponotic genotype B, locally acquired intestinal microsporidiosis will rarely be seen in HIV-infected persons undergoing highly active antiretroviral therapy in the future in Australia.