Analysis of the role of Mycobacterium tuberculosis kasA gene mutations in isoniazid resistance.

Previous studies have suggested that Mycobacterium tuberculosis kasA G312S and G269S gene mutations may represent sequence polymorphisms of the M. tuberculosis East-African-Indian (EAI) and T families, respectively, rather than relating to isoniazid resistance. The present study examined polymorphisms of these two codons in 98 drug-susceptible M. tuberculosis isolates (68 EAI and 30 T isolates). Twenty-eight isolates belonging to a sub-lineage of the EAI family had the kasA G312S mutation, but none of the 30 T isolates had the G269S mutation. The data suggest that the kasA G312S mutation is not related to isoniazid resistance, but represents a sequence polymorphism in a sub-lineage of the EAI family.

Genotype and phenotype relationships and transmission analysis of drug-resistant tuberculosis in Singapore.

SETTING: The small urban country of Singapore. OBJECTIVES: To investigate the relationships between Mycobacterium tuberculosis genotypes and drug-resistant phenotypes and to analyse the transmission of drug-resistant tuberculosis (DR-TB). DESIGN: A 29-month population-based study comparing drug-resistant and drug-susceptible M. tuberculosis isolates. RESULTS: We found that multidrug-resistant (MDR) isolates (n = 41, OR 2.66, 95%CI 1.28-5.50), rifampicin-resistant isolates (n = 48, OR 2.88, 95%CI 1.44-5.76), and streptomycin (SM) resistant isolates (n = 103, OR 3.35, 95%CI 1.99-5.62) were more common among Beijing genotype strains than among non-Beijing strains, while SM-resistant isolates were less common in East-African-Indian (EAI) genotype strains than in non-EAI strains (OR 0.30, 95%CI 0.14-0.64). Based on clustering analysis and drug-resistant patterns, 22 of 230 drug-resistant isolates were found to have likely resulted from recent transmission. The estimated transmission rate of DR-TB was 9.6% and that of MDR-TB was 7.7%. The transmission rate of DR-TB was significantly higher among Beijing genotype strains than non-Beijing strains (12.9% vs. 4.4%; P = 0.034). CONCLUSIONS: Compared to other genotypes, Beijing genotype strains are associated with a higher frequency of drug resistance, including multidrug resistance, and are more transmissible. However, the overall transmission rate of DR-TB in Singapore is low.

AIDS-defining illness diagnosed within 90 days after starting highly active antiretroviral therapy among patients from the TREAT Asia HIV Observational Database.

Using data from TREAT Asia HIV Observational Database (TAHOD), this paper aims to assess the rate of, and factors associated with the diagnosis of new AIDS-defining illness (ADI) within 90 days after antiretroviral treatment. Patients starting three or more antiretroviral combinations and having subsequent follow-up were included. New ADI cases were checked for evidence of immune reconstitution syndrome (IRS). Among the 1185 patients included, 75 (6.3%) were diagnosed with a new ADI within 90 days, giving a rate of 26.8/100 person-years, compared with a further 3.6% cumulative incidence of new ADI between 90 days to one year (4.2/100 person-years). Of the 75 patients, 21 were judged as definitive or presumptive IRS, giving a rate of 7.3/100 person-years. Patients with new ADI generally had lower CD4 counts before treatment started (median, 43 cells/microL). Lower CD4 count, lower body mass index and starting treatment in the same year as the first HIV-positive test done were associated with developing a new ADI. The higher rate of new ADI within 90 days may be partly explained by IRS occurring shortly after treatment. Although it is difficult to identify IRS from observational data, it appears that in TAHOD setting IRS was relatively uncommon.

A randomised controlled trial of oral zinc on the immune response to tuberculosis in HIV-infected patients.

SETTING: The National HIV Unit, Singapore. OBJECTIVE: To test whether zinc supplementation improves the immune response to tuberculosis in HIV-positive patients. DESIGN: A double-blind, randomised, placebo-controlled trial of 28 days of oral zinc sulphate (50 mg of elemental zinc) or placebo in stable adult HIV-positive patients receiving antiretroviral therapy with a CD4 count <200 cells/microl. METHODS: IFN-gamma response to mycobacterial antigen stimulation, CD4/8 cell count, lymphocyte subsets, T-cell receptor excision circle (TREC) levels and viral load were measured at baseline and day 28. RESULTS: Thirty-two patients received zinc and 34 placebo. There was no significant change in the IFN-gamma response to human PPD stimulation in the zinc or placebo groups (placebo baseline: 0.42 +/- 1.03, day 28: 0.84 +/- 1.21 IU/ml, zinc baseline: 1.26 +/- 2.41, day 28: 1.39 +/- 1.88 IU/ml, P = 0.31 between groups), nor any of the other mycobacterial antigens tested. There were no changes in absolute CD4/8 cell levels or other lymphocyte subsets, TREC or viral load. Baseline zinc levels were normal in 62/66 (93.9%) patients. CONCLUSIONS: We found no evidence for recommending pharmacological supplementation with oral zinc in HIV-positive patients without zinc deficiency.

Short-term growth hormone administration at the time of opportunistic infections in HIV-positive patients.

OBJECTIVES: A 12-week course of recombinant human growth hormone is an effective but expensive therapy for established HIV-related wasting. Wasting in HIV disease is often episodic, coinciding with bouts of acute opportunistic infection. We hypothesized that a short course of growth hormone, targeted at the time of opportunistic infection, might improve protein metabolism thereby reducing lean tissue loss. METHODS: HIV-infected men with acute opportunistic infections, who received standard antimicrobial treatment for their infection as well as intensive nutritional counselling and oral energy supplements, were randomized to receive growth hormone or placebo for 14 days. Principal assessments were protein metabolism (measured by 13C-leucine infusion), body composition (measured by DEXA) and safety. RESULTS: There were no significant changes in outcome parameters in the placebo group (n = 11). In the growth hormone group (n = 9), protein catabolic rate decreased by 60% in the fasted state (P = 0.02 versus placebo), lean body mass increased by 2.2 kg (P = 0.03 versus baseline) and fat mass decreased by 0.7 kg (P = 0.002 versus baseline). There was no increase in adverse or serious adverse events in the growth hormone as compared with the placebo group. CONCLUSIONS: A two-week course of growth hormone at the time of acute opportunistic infection in HIV-infected patients improves protein metabolism and body composition during therapy and appears to be safe. This may represent a rational and economical approach to the use of growth hormone therapy.

Prevalence of and risk factors for nasal colonization with Staphylococcus aureus among human immunodeficiency virus-positive outpatients in Singapore.

We studied the prevalence of and risk factors for Staphylococcus aureus nasal colonization in HIV-positive outpatients in Singapore. Overall prevalence was 23% (45 of 195), with 3% (6 of 195) being MRSA. Recent antibiotic use and hospitalization were independent predictors of MRSA colonization. Isolates were genotypically identical to our hospital's inpatient circulating strain.

Risk factors for infection in Malaysian patients with systemic lupus erythematosus.

To determine the incidence, types and risk factors for infection in systemic lupus erythematosus (SLE) patients in Kuala Lumpur, Malaysia, we retrospectively reviewed the medical records of 102 patients with definite SLE attending a specialist clinic. Details of major infections (pneumonia or severe infection requiring intravenous therapy) and minor infections, and their time of onset in relation to immunosuppressive therapy and disease flares were recorded. There were 77 major and 163 minor infections during 564 patient-years of follow-up. In the month following a course of pulse methylprednisolone, the incidence of major infection was 20 times higher and the incidence of minor infection was 10 times higher than at other periods (p < 0.0001). In the month after disease flare, the incidence of major infection was 10 times higher and the incidence of minor infection six times higher than at other times (p < 0.0001). After allowing for methylprednisolone therapy and disease flares, there was no increase in the rate of infections during treatment with azathioprine, oral or intravenous cyclophosphamide. There was no effect of renal involvement on infection rate.

Bioelectrical impedance analysis in human immunodeficiency virus-infected patients: comparison of single frequency with multifrequency, spectroscopy, and other novel approaches.

Bioelectrical impedance (BIA), a prediction method for estimating body water compartments and body cell mass (BCM), is being increasingly used in studies of human immunodeficiency virus (HIV)-related wasting, but there are few validation studies of the method in this group. The aim of this study is to examine the relationship between impedance measurements and body water compartments in patients with advanced HIV disease, and to investigate whether the newer approaches of multifrequency BIA, BIA spectroscopy, logarithmic transformation using a parallel circuit model, and direct calculation from electrical theory offer any advantage over traditional single-frequency BIA. We measured total body water (TBW) by deuterium dilution and extracellular water by bromide dilution in 33 patients with advanced HIV disease. Intracellular water and BCM were calculated from these results. Impedance was measured over a range of frequencies using a multifrequency analyzer. The relationship between impedance index at various frequencies and body water compartments was assessed by correlation and linear regression. We found that impedance index at higher frequencies had a closer relationship to TBW (r = 0.86, standard error of the estimate [SEE] = 2.96 at 1000 kHz) and at lower frequencies a closer relationship to extracellular water (ECW) (r = 0.47, SEE = 3.13 at 0 kHz) than the traditional 50 kHz measurement (r = 0.84, SE = 3.11 for TBW; r = 0.44 SEE = 3.19 for ECW), but the differences were marginal and not statistically significant. None of the other novel approaches tested were significantly better than traditional single frequency measurement. The 50 kHz equation for BCM developed in this study [BCM (kg) = (0.360331 x Ht2/Z50) + (0.151123 x Wt)-2.95] may be useful to investigators using BIA for hIV-wasting studies.

Multiple frequency bioelectrical impedance analysis: a cross-validation study of the inductor circuit and Cole models.

It has been proposed that multiple frequency bioelectrical impedance models of the human body should include an inductive property for the circulatory system, the inductor circuit model (ICM), and that such a model, when coupled with a new method of data analysis, can improve the predictive power of multiple frequency bioelectrical impedance analysis (MFBIA). This hypothesis was tested using MFBIA measurements and gold standard measures of total body and extracellular water volumes in a cross-validation study in two subject groups (viz. controls and HIV). The MFBIA measurements were analysed using the current, widely accepted Cole model and the alternative ICM model which includes an inductive component. Correlations in the range 0.75 to 0.92 (for TBW) and 0.46 to 0.79 (for ECW) for impedance quotients versus gold standard measures within the subject groups were observed. These decreased, to as low as r = 0.50 for TBW and r = 0.29 for ECW, when the derived algorithms were applied to the alternative subject group. These results suggest that lack of portability of MFBIA algorithms between subject groups is not due to an inadequacy of the analogue circuit model per se but is possibly due more to fundamental flaws in the principles associated with its application. These include assuming a constant proportionality of body segment geometries and tissue fluid resistivities. This study has also demonstrated that this inadequacy cannot be overcome by simply introducing an inductive component into the analogue electrical circuit.

Importation of seven cases of an unusual helminthic infection into Singapore and assessment of the risk of local transmission.

Singapore remains vulnerable to the introduction of infectious diseases from other countries due to the high traffic of migrant labour and other visitors. We describe seven cases of migrant workers from West Africa who entered Singapore carrying loaisis, a helminthic infection. The clinical presentation, treatment using single dose ivermectin, potential for transmission, and the need for screening of this infection in Singapore are discussed.

Cryptococcal meningitis resulting in irreversible visual impairment in AIDS patients--a report of two cases.

Cryptococcus neoformans is the leading cause of meningitis in patients with Acquired Immune Deficiency Syndrome (AIDS) and is associated with high mortality rate. Presenting symptoms include fever, nausea and vomiting, altered mentation, headache and meningismus. Cryptococcal meningitis is not infrequently complicated by raised intracranial pressure and visual sequelae (sometimes by blindness). In patients who survive the infection, the most debilitating outcome appears to be visual impairment or blindness. Management of impending visual complication combines medical and surgical treatment modalities. We report two cases of cryptococcal meningitis associated with visual impairment.

Infections in systemic lupus erythematosus patients.

Infection is a frequent problem in patients with systemic lupus erythematosus (SLE), especially in those hospitalised with complications of disease. Infections contribute greatly to the morbidity of patients and are one of the commonest causes of death. The high frequency and unusual spectrum of infections can be attributed to the multiple disturbances of immune function in SLE in combination with the effects of immunosuppressive therapy. High doses of corticosteroids are particularly implicated as a risk factor for infection, although cyclophosphamide may also play a role. The majority of infections where a pathogen can be identified are due to typical gram-positive and negative bacteria. However, there is increasing evidence to indicate that opportunistic infections make a large contribution to the infectious mortality in SLE. Opportunistic infections are considerably under-reported due to difficulties in diagnosis pre-mortem and the fact that they can mimic or be superimposed upon active lupus. The presenting features of tuberculosis, listeriosis, nocardiosis, candidiasis, cryptococcal meningitis, Pneumocystis carinii pneumonia and invasive aspergillosis in patients with SLE are discussed in this review, with particular attention to presentation in SLE patients in Asia. Heightened awareness of the potential for opportunistic pathogens to infect SLE patients, together with earlier investigation and appropriate therapy for such infections, are likely to make a significant contribution to decreasing the mortality in patients with SLE.

Mortality in Malaysians with systemic lupus erythematosus.

One hundred and two patients attending the systemic lupus erythematosus (SLE) clinic of the Department of Medicine, Universiti Kebangsaan Malaysia, were studied retrospectively to determine their survival rates and causes of death. There were 21 deaths. The 1, 5, and 10 year survival rates were 93%, 86% and 70% respectively. There was a bimodal pattern of mortality with more patients dying in the first 2 years or after 5 years of disease. Infection was the direct cause of death in 52% and contributed to a further 19% of deaths. Patients with lupus nephritis had a higher relative risk (RR) of death (RR = 4.34, p < 0.02) although there was no significant increase in risk with any particular histological type on biopsy. Cerebral lupus (RR = 3.08, p < 0.001) and methylprednisolone treatment (RR = 6.24, p < 0.001) were also associated with increased risk of death. Increased awareness of infection and earlier use of antibiotic therapy may improve survival of patients suffering from SLE.

Is a 4-month regimen adequate to cure patients with non-cavitary tuberculosis and negative cultures at 2 months?

A recent trial evaluating a 4-month regimen of standard drugs in adults with non-cavitary tuberculosis (TB) and negative cultures at 2 months failed to demonstrate equivalence compared to the same regimen given for 6 months. To contribute further evidence, data from two trials conducted by the British Medical Research Council (BMRC) comparing 4 and 6 month regimens were re-analysed. The results from the BMRC trials in patients with non-cavitary TB and negative cultures at 2 months were consistent with those from the recent trial. However, given that there was no acquired drug resistance, the estimated 6.6% relapse rate (95%CI 4.3-10.1) across all three trials might be considered acceptable for a 4-month regimen in patients with non-cavitary pulmonary TB.

Validation of three-dimensional laser scanning for the assessment of facial fat changes.

OBJECTIVE: We aimed to evaluate the accuracy of three-dimensional laser scanning as an objective method for detecting facial changes. METHODS: Facial laser scanning was performed at baseline and repeated after a median of 10 months in 24 HIV-infected patients, 12 with ongoing lipodystrophy, five with >10% weight loss and seven with >10% weight gain. Surface volume change was estimated using a standardized technique, and compared with change in cheek fat measured by magnetic resonance imaging (MRI). RESULTS: The median laser scanning surface volume changes were -2.1 (range -4.6 to -0.8) mL in the lipoatrophy group, -1.5 (range -6.8 to -1.3) mL in the weight loss group and +3.1 (range -0.2 to +5.4) mL in the weight gain group (the median MRI cheek fat changes were -4.6, -3.7 and +7.0 mL in the three groups, respectively). Laser scanning and MRI measurements were not significantly associated in lipoatrophy patients (r=0.34, P=0.28), but there was a good association in patients who changed weight (r=0.71, P=0.01). CONCLUSIONS: Laser scanning detects changes in the appropriate direction, although it underestimates MRI-measured cheek fat changes. Laser scanning may be useful as an objective measure of cheek surface volume changes, but needs further validation in larger clinical cohorts.

Experience with the use of a first-line regimen of stavudine, lamivudine and nevirapine in patients in the TREAT Asia HIV Observational Database.

BACKGROUND: The antiretroviral treatment (ART) combination of stavudine, lamivudine and nevirapine (d4T/3TC/NVP) is the most frequently used initial regimen in many Asian countries. There are few data on the outcome of this treatment in clinic cohorts in this region. METHODS: We selected patients from the TREAT Asia HIV Observational Database (TAHOD) who started their first ART regimen with d4T/3TC/NVP. Treatment change was defined as cessation of therapy or the addition or change of one or more drugs. Clinical failure was defined as diagnosis with an AIDS-defining illness, or death while on d4T/3TC/NVP treatment. RESULTS: The rate of treatment change among TAHOD patients starting d4T/3TC/NVP as their first antiretroviral treatment was 22.3 per 100 person-years, with lower baseline haemoglobin (i.e. anaemia) associated with slower rate of treatment change. The rate of clinical failure while on d4T/3TC/NVP treatment was 7.3 per 100 person-years, with baseline CD4 cell count significantly associated with clinical failure. After d4T/3TC/NVP was stopped, nearly 40% of patients did not restart any treatment and, of those who changed to other treatment, the majority changed to zidovudine (ZDV)/3TC/NVP and less than 3% of patients changed to a protease inhibitor (PI)-containing regimen. The rates of disease progression on the second-line regimen were similar to those on the first-line regimen. CONCLUSION: These real-life data provide an insight into clinical practice in Asia and the Pacific region. d4T/3TC/NVP is maintained longer than other first-line regimens and change is mainly as a result of adverse effects rather than clinical failure. There is a need to develop affordable second-line antiretroviral treatment options for patients with HIV infection in developing countries.

The impact of malnutrition on survival and the CD4 count response in HIV-infected patients starting antiretroviral therapy.

BACKGROUND: The impact that malnutrition at the time of starting antiretroviral therapy (ART) has on survival and the CD4 count response is not known. METHODS: A retrospective cohort study of patients attending the national HIV referral centre in Singapore who had a CD4 count less than 250 cells/microL and a measurement of body weight performed at the time of starting ART was carried out. Demographic and clinical variables were extracted from an existing database. Body mass index (BMI) was calculated from the weight in kilograms divided by the square of the height in metres. Moderate to severe malnutrition was defined as BMI less than 17 kg/m(2). Intent-to-treat Cox models were used to determine the predictors of survival. RESULTS: A total of 394 patients were included in the analysis, of whom 79 died during a median study follow-up of 2.4 years. Moderate to severe malnutrition was present in 16% of patients at the time of starting ART, and was found to be a significant independent predictor of death [hazard ratio (HR) 2.19, 95% confidence interval (CI) 1.29-3.73, P=0.004 for those with BMI<17 compared with those with BMI>18.5] as were stage of disease (HR 2.47, 95% CI 1.20-5.07, P=0.014 for those who were at stage C compared with those at stage A) and the type of ART [HR 0.50, 95% CI 0.27-0.93, P=0.03 for highly active antiretroviral therapy (HAART) compared with non-HAART treatment]. Malnutrition did not impair the magnitude of the increase in CD4 count at 6 or 12 months. CONCLUSIONS: Malnutrition at the time of starting ART was significantly associated with decreased survival, but the effect appeared not to be mediated by impaired immune reconstitution. Given the increasing access to ART in developing countries and the high frequency of HIV-associated wasting, studies of nutritional therapy as an adjunct to the initiation of HAART are urgently needed.