Invasive amebiasis in men who have sex with men, Australia

Entamoeba histolytica is a pathogenic ameba that has recently been recognized as an emerging pathogen in men who have sex with men (MSM) in Asia-Pacific countries where it is not endemic, i.e., Japan, Taiwan, and Republic of Korea. We report locally acquired invasive amebiasis in Sydney, Australia, exclusively in MSM.

Prevalence and significance of coagulase-negative staphylococci isolated from blood cultures in a tertiary hospital

Blood cultures (BC) are the most important tool in the diagnosis of bloodstream infections. However, false positive results are associated with increased laboratory costs and inappropriate antibiotic use. In order to determine the prevalence and location of blood cultures contaminated with coagulase-negative staphylococci (CNS), we performed a retrospective analysis of all blood cultures performed at St. Vincent's Hospital, Sydney during a 6-month period. From a total of 4234 patients with BC collected, CNS was isolated from 109 patients (2.6%). 94% of all CNS isolates (101/109) were contaminants. In the emergency department (ED), CNS isolates were significantly more likely to be contaminants (62/63, p<0.02) compared with the rest of the hospital, representing a 3.3% patient BC contamination rate. Treatment for a contaminant with vancomycin was significantly more likely to occur in ward patients (14/28, p<0.01) compared to the rest of the hospital. Duration of therapy did not differ across the hospital. Strategies to reduce the numbers of contaminants should be directed at medical staff in ED. Inappropriate vancomycin therapy could be curtailed by greater clinical microbiology liaison and vancomycin stewardship.

Leishmaniasis, an emerging imported infection: report of 20 cases from Australia

Leishmaniasis is a protozoan infection rarely reported in Australia. However, with the advent of increased international tourism and migration of refugees from endemic regions, leishmaniasis has emerged as an increasingly imported infection. We report 20 cases (17 cutaneous, 2 visceral, and 1 post-kala-azar dermal leishmaniasis). These data highlight the range of species causing leishmaniasis imported in Australia and demonstrate the importance of species identification in determining proper treatment.

Achromobacter xylosoxidans subsp. xylosoxidans prosthetic aortic valve infective endocarditis and aortic root abscesses

We report a case of prosthetic valve infective endocarditis and aortic root abscesses caused by Achromobacter xylosoxidans subsp. xylosoxidans. The patient was an intravenous drug user and had injected amphetamines using 'duck pond water' as a diluent. After surgical intervention and 6 weeks of intravenous meropenem therapy, the patient made an uneventful recovery.

Comparison of stool antigen detection kits to PCR for diagnosis of amebiasis

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. Vincent's 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.

Candida dubliniensis meningitis as delayed sequela of treated C. dubliniensis fungemia

We present a case of Candida dubliniensis meningitis that developed 2 months after apparently successful treatment of an episode of C. dubliniensis candidemia in a heart-lung transplant recipient in Australia. This case highlights the importance of follow-up in patients with candidemia or disseminated infection, especially in immunosuppressed patients.

Gorillas are a host for Dientamoeba fragilis: an update on the life cycle and host distribution

Dientamoeba fragilis is a gastrointestinal protozoan that has a worldwide distribution and is emergeing as a common cause of diarrhea. As D. fragilis has a propensity to cause chronic illness with symptoms similar to irritable bowel syndrome (IBS) it is not surprising that some patients with D. fragilis are misdiagnosed as having IBS. In contrast to most other pathogenic protozoa very little is known about its life cycle, epidemiology and mode of transmission. What role animal reservoirs play in the transmission of this parasite is unknown. Consequently we undertook a prospective study to determine the host distribution of D. fragilis. Over a 2-year-period, 608 faecal samples from a wide range of animal and bird species, including pigs and other food species, were screened using permanent stained smears for the presence of D. fragilis. Trophozoites of D. fragilis were only detected in Western lowland gorillas (3/10) (Gorilla g. gorilla) and confirmed by PCR targeting the SSU rRNA gene. The limited host range detected suggests human infection may not involve transmission from other animal species. In addition, we provide an update on the limited knowledge about the life cycle of this parasite and its host distribution.

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

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-beta-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.

Declining incidence of intestinal microsporidiosis and reduction in AIDS-related mortality following introduction of HAART in Sydney, Australia

Limited data exist regarding the incidence of intestinal microsporidiosis following the introduction of highly active antiretroviral therapy (HAART) in Australia. At St Vincent's Hospital, Sydney, all faecal samples submitted for diarrhoea from HIV-infected patients between 1995 and 2006 underwent screening for microsporidiosis. A total of 3564 patients (7366 faecal specimens) was examined, resulting in 159 patients identified with microsporidiosis. The incidence of microsporidiosis declined from 11% in 1995 to 0% from 2004 onwards. At presentation the majority of patients were severely immunocompromised (median CD4 105 cells/mm(3)), with only 16% of patients on effective HAART. Twenty-four patients (24/76, 32%) died within a median of 22 months following microsporidiosis diagnosis. Significant predictors of AIDS-related mortality at presentation included the level of immunodeficiency and receiving no or ineffective HAART (P<0.05). Patients presenting after 1998 had a significant reduction in the risk of AIDS-related mortality compared with patients presenting before 1998 (hazard ratio 0.27, 95% CI 0.79-0.92). All 52 (68%) surviving patients were on effective HAART, with a median CD4 count 382 cells/mm(3) and HIV RNA of < 50 copies/ml at follow-up (median 4 years). The dramatic decline of intestinal microsporidiosis in our study reconfirms the importance of effective HAART in preventing advanced immunodeficiency, opportunistic infections and associated AIDS-related deaths.

Laboratory diagnostic techniques for Entamoeba species

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.

Rhizopus microsporus var. rhizopodiformis sinus-orbital zygomycosis in an immunosuppressed patient: successful treatment with posaconazole after a complicated clinical course

A case of sinus-orbital Rhizopus microsporus var. rhizopodiformis infection in a patient with graft versus host disease following allogeneic blood stem cell transplantation is reported. Commercially available pea straw compost used for gardening was suspected to be the source of the infection. After an initial relapse, treatment with surgical debridement, liposomal amphotericin B and posaconazole was successful.

Bordetella petrii from a clinical sample in Australia: isolation and molecular identification

The first isolation of Bordetella petrii from a patient with chronic suppurative mastoiditis is reported. Molecular characterization of the isolate was performed by sequencing the small-subunit rRNA gene, the Bordetella outer-membrane protein A gene (ompA) and the RisA response regulator gene (risA). This is the first reported case of B. petrii causing suppurative mastoiditis and only the second documented case of a clinically significant B. petrii isolate.

Prevalence of enteric protozoa in human immunodeficiency virus (HIV)-positive and HIV-negative men who have sex with men from Sydney, Australia

A prospective, comparative study of the prevalence of enteric protozoa was determined among human immunodeficiency virus (HIV)- positive and HIV-negative men who have sex with men (MSM) in Sydney, Australia. A total of 1,868 patients submitted stool specimens; 1,246 were from MSM (628 HIV positive and 618 HIV positive) and 622 from non-MSM were examined over a 36-month period. A total of 651 (52.2%) stool specimens from MSM were positive for protozoa compared with 85 (13%) from non-MSM. There was a significant difference in the prevalence of Blastocystis hominis, Endolimax nana, Entamoeba histolytica/dispar complex, Entamoeba hartmanni, Iodamoeba butschlii, and Enteromonas hominis detected between MSM and non-MSM (P<0.001). The only notable difference between HIV-negative and HIV-positive MSM was that HIV-infected MSM were found to more likely have a Cryptosporidium parvum infection. Entamoeba histolytica was found in 3 patients, E. dispar in 25, and E. moshkovskii in 17, all of whom were MSM. When compared with a control group, MSM were significantly more likely to harbor intestinal protozoa and have multiple parasites present. The results of this study show high rates of enteric parasites persist in MSM and highlight the importance of testing for intestinal parasites in MSM. This is the first report of E. moshkovskii from MSM.

Active surveillance for candidemia, Australia

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

Population-based surveillance for candidemia in Australia from 2001 to 2004 identified 1,095 cases. Annual overall and hospital-specific incidences were 1.81/100,000 and 0.21/1,000 separations (completed admissions), respectively. Predisposing factors included malignancy (32.1%), indwelling vascular catheters (72.6%), use of antimicrobial agents (77%), and surgery (37.1%). Of 919 episodes, 81.5% were inpatient healthcare associated (IHCA), 11.6% were outpatient healthcare associated (OHCA), and 6.9% were community acquired (CA). Concomitant illnesses and risk factors were similar in IHCA and OHCA candidemia. IHCA candidemia was associated with sepsis at diagnosis (p<0.001), death <30 days after infection (p<0.001), and prolonged hospital admission (p<0.001). Non–Candida albicans species (52.7%) caused 60.5% of cases acquired outside hospitals and 49.9% of IHCA candidemia (p = 0.02). The 30-day death rate was 27.7% in those >65 years of age. Adult critical care stay, sepsis syndrome, and corticosteroid therapy were associated with the greatest risk for death. Systematic epidemiologic studies that use standardized definitions for IHCA, OHCA, and CA candidemia are indicated.

Lymphogranuloma venereum in Australia: anorectal Chlamydia trachomatis serovar L2b in men who have sex with men

Lymphogranuloma venereum (LGV) is a sexually transmitted infection that is causing an ongoing epidemic in men who have sex with men (MSM) in Europe, the United Kingdom, and North America. Twenty-nine rectal swabs positive for Chlamydia trachomatis were analyzed by real-time PCR for the presence of LGV serovars. Genotyping revealed an identical L2b serovar from four specimens. All patients were MSM and human immunodeficiency virus infected. Three of the four presented with severe ulcerative proctitis. We report a cluster of rectal LGV serovar L2b infections in Sydney, Australia.

PCR detection of Entamoeba histolytica, Entamoeba dispar, and Entamoeba moshkovskii in stool samples from Sydney, Australia

This study investigated the presence of Entamoeba histolytica, Entamoeba dispar, and Entamoeba moshkovskii in stool samples from a patient population in Sydney, Australia. Stool samples were tested by microscopy and PCR. Five patients were found with E. histolytica infections, while E. dispar and E. moshkovskii were observed in 63 (70.8%) and 55 (61.8%) patients, respectively, by PCR. This is the first study in Australia using molecular techniques to determine the presence of E. histolytica, E. dispar, and E. moshkovskii.

Dientamoeba fragilis as a cause of travelers' diarrhea: report of seven cases

Dientamoeba fragilis is a pathogenic trichomonad parasite that causes gastrointestinal disease in humans. We report seven cases of travelers' diarrhea caused by D fragilis in patients who had traveled to overseas destinations within Asia or the Pacific which occurred over an 8-month period. Patients presented with diarrhea lasting from 5 days to over 4 weeks. Dientamoeba fragilis should be considered as a cause of diarrhea in returning travelers.

Veillonella parvula discitis and secondary bacteremia: a rare infection complicating endoscopy and colonoscopy?

We report a case of Veillonella parvula lumbar discitis and secondary bacteremia confirmed by molecular characterization of the 16S rRNA genes. Identification of the organism was essential for an appropriate choice of antimicrobial therapy following the failure of empirical flucloxacillin. Veillonella spp. are normal flora of the gastrointestinal tract, raising the possibility that an endoscopy and colonoscopy performed 8 weeks prior to presentation, during which small intestinal and rectal biopsies were obtained, was the portal of entry. This case highlights the importance of obtaining a microbiologic diagnosis, particularly in patients who previously have had procedures involving instrumentation.

Irritable bowel syndrome: a review on the role of intestinal protozoa and the importance of their detection and diagnosis

Irritable bowel syndrome (IBS) is a functional gastrointestinal disorder in which abdominal pain is associated with a defect or a change in bowel habits. Gut inflammation is one of the proposed mechanisms of pathogenesis. Recent studies have described a possible role for protozoan parasites, such as Blastocystis hominis and Dientamoeba fragilis, in the etiology of IBS. Dientamoeba fragilis is known to cause IBS-like symptoms and has a propensity to cause chronic infections but its diagnosis relies on microscopy of stained smears, which many laboratories do not perform, thereby leading to the misdiagnosis of dientamoebiasis as IBS. The role of B. hominis as an etiological agent of IBS is inconclusive, due to contradictory reports and the controversial nature of B. hominis as a human pathogen. Although Entamoeba histolytica infections occur predominately in developing regions of the world, clinical diagnosis of amebiasis is often difficult because symptoms of patients with IBS may closely mimic those patients with non-dysenteric amoebic colitis. Clinical manifestations of Giardia intestinalis infection also vary from asymptomatic carriage to acute and chronic diarrhoea with abdominal pain. These IBS-like symptoms can be continuous, intermittent, sporadic or recurrent, sometimes lasting years without correct diagnosis. It is essential that all patients with IBS undergo routine parasitological investigations in order to rule out the presence of protozoan parasites as the causative agents of the clinical signs.

Post-kala-azar dermal leishmaniasis due to Leishmania infantum in a human immunodeficiency virus type 1-infected patient

We report the first case of post-kala-azar dermal leishmaniasis due to Leishmania infantum in a human immunodeficiency virus type 1-infected patient in Australia. Molecular characterization of the isolate was performed using PCR restriction fragment length polymorphism targeting both repetitive sequences from Leishmania nuclear DNA and repetitive kinetoplast DNA minicircles for species differentiation.

Secondary syphilis presenting as tonsillitis in three patients

We describe three homosexual men presenting to the ear, nose and throat clinic with severe tonsillitis. All were subsequently diagnosed with secondary syphilis of the tonsil. Syphilis should be considered as a diagnosis in high risk patients presenting with tonsillar lesions, even in the absence of other classical features of the disease.

Evaluation of three diagnostic methods, including real-time PCR, for detection of Dientamoeba fragilis in stool specimens

Dientamoeba fragilis is a protozoan parasite of humans that infects the mucosa of the large intestine and is associated with gastrointestinal disease. We developed a 5' nuclease (TaqMan)-based real-time PCR assay, targeting the small subunit rRNA gene, for the detection of D. fragilis in human stool specimens and compared its sensitivity and specificity to conventional PCR and microscopic examination by a traditional modified iron-hematoxylin staining procedure. Real-time PCR exhibited 100% sensitivity and specificity.

Minor changes in calculated creatinine clearance and anion-gap are associated with tenofovir disoproxil fumarate-containing highly active antiretroviral therapy

BACKGROUND

Tenofovir disoproxil fumarate (Tenofovir DF, TDF), the first nucleotide reverse transcriptase inhibitor approved for the treatment of HIV disease, has been associated with renal dysfunction in isolated cases. The aim of this study was to assess changes in renal parameters in individuals receiving TDF- and non-TDF-containing highly active antiretroviral therapy (HAART).

METHODS

All individuals on HAART attending our clinic were included in the analysis. Time-weighted changes in serum creatinine, calculated creatinine clearance (CCrCl) and anion-gap were assessed for individuals on TDF- and non-TDF HAART.

RESULTS

Of 948 individuals on HAART, 290 (31%) and 618 (65%) were on TDF- and non-TDF HAART, with 40 (4%) having ceased TDF HAART. Baseline values for serum creatinine, CCrCl and anion-gap were similar for those on TDF- and non-TDF HAART. In a multivariate analysis, statistically significant differences were observed in time-weighted change from baseline in anion-gap and CCrCl between individuals on TDF- and non-TDF HAART [mean difference in change between groups: anion-gap 0.78 mmol/L (standard error, 0.19) and CCrCl-6.80 (standard error 2.2); P = 0.005 and P = 0.032, respectively] after adjusting for baseline anion-gap and CCrCl, respectively. Two cases of TDF-associated renal failure were observed.

CONCLUSION

Overt renal failure with TDF HAART is rare. However, subtle but statistically significant changes in anion-gap and CCrCl were observed which were associated with TDF HAART. These parameters may be of use in monitoring individuals on HAART.