Eosinopenia as a diagnostic marker of bloodstream infection in hospitalised paediatric and adult patients: a case-control study.

The objective of this study was to assess whether eosinopenia was a reliable diagnostic marker of bloodstream infection in hospitalised adult and paediatric patients. The design was a case-control study, set in a tertiary adult and paediatric hospital. A total of 157 adult and 85 paediatric patients with bloodstream infection ('cases') were compared to 195 and 94 randomly selected adult and paediatric patients who had clinical suspicion of bloodstream infection but with a negative blood culture ('controls') respectively. Patients with haematological or immunosuppressive disease and control patients who were treated with antibiotics within one week prior to the blood culture were excluded. Eosinopenia, or undetectable eosinophil count (<0.01 x 10(9) or <10/mm3), was more common among the cases than the controls (46.5% vs 21.5%, respectively). The specificity of eosinopenia to predict bloodstream infection in adult patients was reasonable (79%, 95% confidence interval [CI] 74 to 82), but its sensitivity was low (47%, 95% CI 41 to 52). The absolute eosinophil count only had a modest ability to discriminate bloodstream infections from controls in adult patients (area under receiver operating characteristic curve 0.349, 95% CI 0.288 to 0.411). Eosinophil counts had very little overall predictive ability (area under receiver operating characteristic curve 0.448, 95% CI 0.363 to 0.533, P=0.237), and the sensitivity (54%, 95% CI 47 to 61) and specificity (56%, 95% CI 49 to 63) of eosinopenia to predict bloodstream infection in paediatric patients were both low. In the multivariate analyses, only C-reactive protein concentrations and neutrophil counts, but not eosinopenia, were significantly associated with the presence of bloodstream infection in both adult and paediatric patients. The presence of eosinopenia can be considered as an inexpensive warning test for bloodstream infection in hospitalised adult patients so that further investigations can be initiated. An absence of eosinopenia is, however not sensitive enough to exclude bloodstream infection. C-reactive protein concentrations and neutrophil counts were both better markers of bloodstream infection than eosinopenia in hospitalised paediatric and adult patients.

Decreased IFNγ production correlates with diminished production of cytokines by dendritic cells in patients infected with hepatitis C virus and receiving therapy.

Toll-like receptor (TLR) expression and the signalling pathways that lead to the production of accessory cytokines by antigen-presenting cells (APCs) both have potential to limit T-cell responses to viral antigens. Here, expression of TLR and retinoic acid inducible gene I (RIG-I) and responses evoked through these proteins were evaluated in patients chronically infected with HCV, before and during pegylated interferon-α (IFNα) and ribavirin therapy. Expression of TLR2, 3, 4, 7, 9 and RIG-I on APCs and cytokine production by DCs were measured by flow cytometry. Production of IL-12 by myeloid dendritic cells (mDCs), IFNα by plasmacytoid cells (pDCs) and IFNγ by peripheral blood mononuclear cells was measured after stimulation with TLR ligands. IFNγ ELISpot responses to HCV and CMV antigens declined on therapy. TLR and RIG-I expression on mDCs, pDCs, B cells and monocytes was either similar or higher in patients than that in controls and generally increased during therapy. Therapy impaired IL-12 and IFNα production by DCs and reduced production of IFNγ by PBMCs after stimulation with ligands for TLR3, TLR7/8, TLR9 and RIG-I. This was independent of whether patients attained a sustained virological response. HCV disease and interferon-based therapy reduced IFN-γ responses to HCV antigens and TLR agonists. This was not accompanied by reduced expression of pertinent TLR but correlated with diminished production of co-stimulatory cytokines by DCs stimulated via TLR.

Could a loss of memory T cells limit responses to hepatitis C virus (HCV) antigens in blood leucocytes from patients chronically infected with HCV before and during pegylated interferon-alpha and ribavirin therapy?

The proportions and activation status of T cells may influence responses to hepatitis C virus (HCV) and treatment outcome in patients receiving pegylated interferon (IFN)-alpha/ribavirin therapy. We confirmed that IFN-gamma enzyme-linked immunospot (ELISPOT) responses to HCV are poor in HCV patients and showed that responses to HCV and cytomegalovirus (CMV) antigens decrease during therapy. This was most apparent in patients with sustained virological response (SVR). Baseline frequencies of CD4+ effector memory (TEM) T cells were lower in SVR than non-SVR. Proportions of CD4+ and CD8+ TEM and terminally differentiated effector memory (TEMRA) T cells declined on therapy in SVR, as did proportions of Fas+ CD8+ TEMRA T cells. Baseline frequencies of programmed death (PD)-1-expressing CD4+ TEM and TEMRA T-cells were higher in SVR. Therapy increased percentages of PD-1+ CD4+ central memory (TCM) T cells and PD-1+ CD8+ TEM and TEMRA T cells in SVR. We conclude that successful therapy depletes circulating antigen-specific CD4+ T cell responses. This paralleled decreases in proportions of effector memory T cells and higher percentages of CD4+ TCM T cells expressing PD-1.

Outbreak of invasive methicillin-resistant Staphylococcus aureus infection associated with acupuncture and joint injection.

OBJECTIVE: To describe an outbreak of invasive methicillin-resistant Staphylococcus aureus (MRSA) infection after percutaneous needle procedures (acupuncture and joint injection) performed by a single medical practitioner. SETTING: A medical practitioner's office and 4 hospitals in Perth, Western Australia. PATIENTS: Eight individuals who developed invasive MRSA infection after acupuncture or joint injection performed by the medical practitioner. METHODS: We performed a prospective and retrospective outbreak investigation, including MRSA colonization surveillance, environmental sampling for MRSA, and detailed molecular typing of MRSA isolates. We performed an infection control audit of the medical practitioner's premises and practices and administered MRSA decolonization therapy to the medical practitioner. RESULTS: Eight cases of invasive MRSA infection were identified. Seven cases occurred as a cluster in May 2004; another case (identified retrospectively) occurred approximately 15 months earlier in February 2003. The primary sites of infection were the neck, shoulder, lower back, and hip: 5 patients had septic arthritis and bursitis, and 3 had pyomyositis; 3 patients had bacteremia, including 1 patient with possible endocarditis. The medical practitioner was found to be colonized with the same MRSA clone [ST22-MRSA-IV (EMRSA-15)] at 2 time points: shortly after the first case of infection in March 2003 and again in May 2004. After the medical practitioner's premises and practices were audited and he himself received MRSA decolonization therapy, no further cases were identified. CONCLUSIONS: This outbreak most likely resulted from a breakdown in sterile technique during percutaneous needle procedures, resulting in the transmission of MRSA from the medical practitioner to the patients. This report demonstrates the importance of surveillance and molecular typing in the identification and control of outbreaks of MRSA infection.

The frequency of high-grade intraepithelial neoplasia in anal/perianal warts is higher than previously recognized.

A retrospective review of the prevalence of intraepithelial neoplasia (IN) in surgically removed perianal/anal warts from December 1995 to December 2004 was undertaken in patients referred to the Sexual Health Clinic at Royal Perth Hospital. Data were analysed from 115 men and 38 women, 29 of whom had HIV infection (27 men and two women). Perianal/anal IN within the warts was found in 78% (52% high grade) of men with HIV infection. In men without HIV infection, the overall rate of IN within warts was 33% (20% high grade). The IN rate was 8.3% for HIV-negative women (2.8% high grade). Rates of IN within perianal/anal warts in men with or without HIV infection are higher than previously reported, and suggest the likelihood of a substantial increase in the future incidence of anal cancer. The association between IN and genital warts needs to be further studied.

Immune restoration disease after the treatment of immunodeficient HIV-infected patients with highly active antiretroviral therapy.

BACKGROUND: To determine if infectious disease events in HIV-infected patients treated with highly active antiretroviral therapy (HAART) are a consequence of the restoration of pathogen-specific immune responses, a single-centre retrospective study of all HIV-infected patients commencing HAART prior to 1 July 1997 was undertaken to determine the incidence, characteristics and time of onset of disease episodes in HAART responders (decrease in plasma HIV RNA of > 1 log10 copies/mL). METHODS: Baseline and post-therapy changes in CD4 T-cell counts and HIV RNA were compared in patients with and without disease and delayed-type hypersensitivity responses to mycobacterial antigens were measured in selected patients. RESULTS: Thirty-three of 132 HAART responders (25%) exhibited one or more disease episodes after HAART, related to a pre-existent or subclinical infection by an opportunistic pathogen. Disease episodes were most often related to infections by mycobacteria or herpesviruses but hepatitis C virus (HCV), molluscum contagiosum virus and human papilloma virus were also implicated. They were most common in patients with a baseline CD4 T-cell count of < 50/uL and occurred most often during the first 2 months of therapy and when CD4 T-cell counts were increasing. Mycobacteria- and HCV-related diseases were associated with restoration of pathogen-specific immune responses. CONCLUSIONS: We conclude that improved immune function in immunodeficient patients treated with HAART may restore pathogen-specific immune responses and cause inflammation in tissues infected by those pathogens.

Bartonella henselae associated with Parinaud's oculoglandular syndrome.

Bartonella henselae was recovered from the conjunctival scraping of a 38-year-old woman who presented with a 2-week history of tender preauricular lymphadenopathy and a 1-day history of a red left eye. Dry adherent colonies were observed on agar plates at 21 days of incubation, and the isolate was identified through conventional and molecular tests. Polymerase chain reaction (PCR) amplification of a specific region of the 16S rRNA gene and confirmation by a separate PCR reaction with hybridization of the product with a B. henselae-specific probe confirmed the isolate as B. henselae. This is the first reported isolation of the causative agent of cat scratch disease from ocular tissue in a patient with Parinaud's oculoglandular syndrome.

A comparison of the diseases caused by Ross River virus and Barmah Forest virus.

Barmah Forest virus (BFV) and Ross River virus (RRV) are mosquito-borne viruses with similar vectors and environmental requirements. They cause diseases characterised by arthralgia, arthritis and myalgia, often accompanied by fever and rash. Arthritis is more common and more prominent in RRV disease and rash is more common and florid with BFV infection, although the diseases cannot be reliably distinguished by their clinical symptoms. Diagnosis is based on serological tests and a definite diagnosis of recent infection requires the demonstration of rising titres of IgG. Arthralgia, myalgia and lethargy may continue for at least six months in up to half of patients with RRV, but in only about 10% of patients with BFV. Both diseases are managed symptomatically.

Detection of antibodies to Bartonella henselae in clinically diagnosed cat scratch disease.

OBJECTIVE: To determine the usefulness of an indirect immunoflourescence antibody test for antibodies to Bartonella henselae in diagnosing cat scratch disease (CSD). DESIGN AND SETTING: Retrospective case survey of 354 patients whose sera were tested for antibodies to B. henselae at Royal Perth Hospital, Perth, and the Institute of Clinical Pathology and Medical Research, Sydney. In 1994; and measurement of the background prevalence of antibodies to B. henselae. MAIN OUTCOME MEASURES: Prevalence of antibodies to B. henselae, odds of a positive titre (> or = 64) in patients with and without specific risk factors for CSD and clinical features of the disease; prevalence of antibodies to B. henselae in randomly selected blood donors. RESULTS: Demographic, clinical and cat contact data were available for 303 patients. Sixty-four (21.1%) had a positive titre, as did 53 of 98 (54%) patients with a history of cat contact and lymphadenopathy. This proportion increased to 62% (38 of 61 patients) in patients with a history of cat scratch or bite and to 90.3% (28 of 31) in those with cat contact, lymphadenopathy and histological evidence of granulomatous lymphadenitis. Patients who developed lymphadenopathy after cat contact were significantly more likely to have a positive titre than those without this history (odds ratio [OR], 20.8; 95% confidence interval [95% Cl], 9.6-46; P < 0.0001). Inclusion of a history of a cat scratch or bite significantly raised the odds of being seropositive (OR, 13.7; 95% Cl, 6.8-28.1; P < 0.0001), and the presence of granulomas on lymph node biopsy further increased the odds (OR, 124.4; 95% Cl, 19.4-1073; P < 0.0001). The prevalence of antibodies to B. henselae in random blood donors in New South Wales was about 5% (five of 102 sera samples). CONCLUSIONS: The immunofluorescence antibody test for B. henselae can be expected to be positive in just over half the patients with clinically suspected CSD, and it has a positive predictive value of 83%. In a significant number of cases the diagnosis cannot be made on the basis of the results of immunofluorescence antibody testing alone and further investigations, including lymph node biopsy, may be required.

Bartonella henselae is a causative agent of cat scratch disease in Australia.

We report the first isolation of Bartonella henselae from the blood and fleas of a cat of a patient with cat scratch disease (CSD) in Australia. A 49-year-old man presented with a history that 3 weeks after he had removed fleas from his cat he had developed fever, lethargy and anorexia for 3 days. This was followed by the appearance of axillary lymphadenopathy. There was no history of a bite or scratch and no primary lesion on the skin. Two fine needle aspirates of the axillary lymph node showed granulomatous lymphadenitis with no organisms seen by Warthin-Starry silver staining or electron microscopy. No organism was cultured from the patient's lymph node aspirates or blood cultures processed by lysis centrifugation. However, the polymerase chain reaction (PCR) using p24E and p12B primers gave a 280 bp band indistinguishable from Bartonella henselae when using DNA extracted from the lymph node aspirates and the patient's blood leucocytes. DNA sequencing of the PCR product from the patient's blood showed that the DNA was from Bartonella henselae. The patient's serum had a titre of 1024 in an indirect immunofluorescence antibody test for Bartonella henselae. Bartonella henselae was subsequently cultured from fleas and blood taken from the patient's cat. This case provides evidence that Bartonella henselae is a causative agent of CSD in Australia and supports a possible role for fleas in transmission of the disease.

Primary varicella in adult renal transplant recipients: a report of three cases plus a review of the literature.

Disseminated primary varicella zoster infection in renal transplant patients can result in severe and often fatal illness. The disease tends to be much more severe in adults with an 80% mortality in the only reported series (1). We report 3 cases of severe disseminated varicella zoster in adult renal transplant patients who all survived. Early diagnosis, institution of intravenous acyclovir 10 mg/kg tds, zoster immunoglobulin, cessation of azathioprine treatment and aggressive supportive care may improve an otherwise bleak prognosis.

Catheter-related septicemia caused by a vancomycin-resistant Coryneform CDC group A-5.

A case of catheter-related septicemia, due to Coryneform CDC group A-5, in an 11 yr old boy with acute myelomonocytic leukemia is discussed. The child failed to respond to initial antibiotic therapy, even following the addition of vancomycin. Laboratory studies later showed the organism to be vancomycin resistant but cefotaxime susceptible.

In vivo boosting of lung natural killer and lymphokine-activated killer cell activity by interleukin-2: comparison of systemic, intrapleural and inhalation routes.

Natural killer (NK) cells are thought to play a role in host defence against malignancy and infection, in immunoregulation and as precursor cells in a generation of lymphokine-activated killer (LAK) cells which can lyse NK-resistant tumour cells. As the lung is a major site for malignancy and infection and as there are large numbers of lymphoid cells including NK cells in the interstitial compartment of the lung, we evaluated the capacity of interleukin-2 (IL-2), a lymphokine capable of augmenting NK activity in vitro, to augment lung NK cell activity in vivo, using different routes of IL-2 administration. We compared both systemic (i.v. and i.p.) and local (intrapleural and inhalation) routes of IL-2 administration (50,000 U/daily for 5 days) using CBA mice, assessing NK and LAK cell activity in the spleen (systemic) and in the lung. The target cells used for these studies were the YAC-1 (NK-sensitive) and P815, NO36 and HA56 (NK-resistant, LAK-sensitive) cell lines. Splenic NK activity was increased by 1.4-1.9-fold for i.v./i.p., respectively, compared with controls with both systemic routes of administration, and lung NK activity was increased 3.2-fold and 3.8-fold (i.v./i.p, respectively, P less than 0.05), to levels which were comparable to systemic (splenic) NK activity following the same therapy. Intrapleural IL-2 administration similarly enhanced lung NK activity (3.3-fold) and splenic NK activity (1.3-fold; P less than 0.05 versus controls for both). Surprisingly, inhaled IL-2 suppressed both splenic and lung NK cell activity (84 +/- 8% and 78 +/- 10% suppression, respectively, P less than 0.05). LAK cell activity was also enhanced in the lung by 1.8-8-fold in response to i.v., i.p. and intrapleural IL-2, whereas inhaled IL-2 was ineffective in generating LAK cell activity. These results suggest that the systemic and intrapleural administration of IL-2 effectively boost pulmonary NK and LAK activity whereas inhalation of IL-2 does not. Thus, in clinical situations where boosting of local lung NK or LAK cell activity is desired, these routes of IL-2 administration may be effective.

Genetically determined resistance to murine cytomegalovirus and herpes simplex virus in newborn mice.

Mice which were infected with the herpesvirus murine cytomegalovirus or herpes simplex virus type 1 on the day of birth exhibited mouse strain-dependent differences in the development of lethal disease. The pattern of resistance among the strains was distinct for each virus and closely resembled that reported in adult mice. However, much lower doses of the viruses were required in newborn mice to reveal these resistance patterns. For murine cytomegalovirus, both H-2-associated and non-H-2 genes conferred resistance, and, as has been shown for adults, there was a 25-fold difference in the dose required to kill 50% of the animals belonging to the most resistant and susceptible strains. The resistance of newborn mice to herpes simplex virus type 1 was conferred by non-H-2 genes in C57BL/6 mice, as has been reported for adults, and newborn C57BL/6 mice were considerably more resistant than mice of susceptible strains. Resistance was also reflected in the titer of these viruses in the spleen or liver early in infection and, with murine cytomegalovirus, in the survival time of infected mice. The resistance of newborn mice to lethal disease was not conferred postnatally by the mother. This appears to be the first report of genetically determined resistance to herpesviruses in newborn mice. Such autonomous virus-specific resistance may provide a significant barrier to naturally acquired infection in genetically resistant strains. Similar genetically regulated mechanisms may protect the newborns of many species, including humans, against infection with herpesviruses.

The genetic background modulates the effect of the beige gene on susceptibility to cytomegalovirus infection in mice.

Homozygous beige (bg/bg) mice were more susceptible to the development of fatal disease induced by murine cytomegalovirus (MCMV) than their bg/ + littermates. However, the increase in susceptibility depended on the genetic background of the strain carrying the bg gene. C57BL/6, SB/Le, DBA/2, and CBA bg/bg mice showed, respectively, 2.5-, 3.2-, 9.5-, and 18.6-fold increases in susceptibility compared with the corresponding bg/+ animals. Beige mice showed higher liver titres of MCMV than bg/ + by the 2nd or 3rd day after infection, and tissue damage was also greater. Splenic NK cells were not detected in uninfected bg/bg mice, and after virus inoculation the increment in cytotoxicity was greater in bg/ + than in bg/bg mice. However, cytotoxicity towards WEHI-164 cells was not impaired in bg/bg mice and was not augmented by MCMV. Interferon titres were also not impaired by the beige mutation. Of the strains examined, CBA had the highest endogenous levels of NK cells and were most genetically resistant to MCMV. Thus, our observation that the beige gene had the greatest effect on susceptibility in this strain suggests that NK cells are important mediators of genetically determined resistance to MCMV.

The role of the thymus in the maintenance of natural killer cells in vivo.

This report describes a model for investigating the role of the thymus in regulating natural killer (NK) cell activity in vivo. Evidence is presented that the thymus can regulate NK cells, and that at least some NK cells can develop without thymic help. Marrow from thymectomized rats depleted of circulating T cells by thoracic duct cannulation was transplanted into rats without a thymus (1 degree ATX.BM). These 1 degree ATX.BM rats had NK cell levels above controls 3 months after reconstitution but markedly depressed NK cell levels by 9 months. When 1 degree ATX.BM marrow was used to reconstitute rats with or without a thymus, those without a thymus (2 degrees ATX.BM) exhibited low NK cell levels after 3 months, and a similar result was obtained when 2 degrees ATX.BM marrow was used to reconstitute 3 degrees ATX.BM rats. The low NK cell levels in 2 degrees and 3 degrees ATX.BM rats were due to a deficiency in spontaneously cytotoxic NK cells, as they had normal numbers of interferon-responsive pre-NK cells. Spleen cells from 2 degrees and 3 degrees ATX.BM rats produced less interferon than control spleen cells when cultured with P815 tumor cells in vitro. However, 2 degrees and 3 degrees ATX.BM rats had higher numbers of large granular lymphocytes than controls despite their low NK cell levels. In marked contrast to 2 degrees and 3 degrees ATX.BM rats, spleen cells from 4 degrees ATX.BM rats had higher levels of cytotoxicity and a higher frequency of both spontaneously cytotoxic and pre-NK cells than controls. The 4 degrees ATX.BM rats also had the highest frequency of large granular lymphocytes in the spleen.