Sensitivity of an immunoenzymatic test for detection of ant-L. brasiliensis antibodies compared to other tests used for the diagnosis of American cutaneous leishmaniasis

The diagnosis of American cutaneous leishmaniasis (ACL) is frequently based on clinical and epidemiological data associated with the results of laboratory tests. Some laboratory methods are currently being applied for the diagnosis of ACL, among them the indirect immunofluorescence reaction (IIFR), the Montenegro skin test (MST), histopathological examination, and the polymerase chain reaction (PCR). The performance of these methods varies in a considerable proportion of patients. After the standardization of an immunoenzymatic test (ELISA) for the detection of IgG in the serum of patients with ACL using a crude Leishmania braziliensis antigen, the results obtained were compared to those of other tests routinely used for the diagnosis. The tests revealed the following sensitivity, when analyzed separately: 85% for ELISA IgG, 81% for PCR, 64.4% for MST, 58.1% for IIFR, and 34% for the presence of parasites in the biopsy. ELISA was positive in 75% of patients with ACL presenting a negative MST, in 84.8% of ACL patients with negative skin or mucous biopsies for the presence of the parasite, and in 100% of cases with a negative PCR. Thus, ELISA presented a higher sensitivity than the other tests and was useful as a complementary method for the diagnosis of ACL.

Self-diagnosis of active head lice infestation by individuals from an impoverished community: high sensitivity and specificity

To compare sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of self-diagnosis for head lice infestation with visual inspection, we conducted a study in an urban slum in Brazil. Individuals were asked about active head lice infestation (self-diagnosis); we performed visual inspection and thereafter wet combing (gold standard). Of the 175 individuals included, 77 (44%) had an active head lice infestation. For self-diagnosis, sensitivity (80.5%), specificity (91.8%), PPV (88.6%) and NPV (85.7%) were high. Sensitivity of visual inspection was 35.1%. Public health professionals can use self-diagnosis as a diagnostic tool, to estimate accurately prevalence of pediculosis in a community, and to monitor ongoing intervention strategies.

PREVALENCE OF DRUG RESISTANCE AND VIRULENCE FEATURES IN Salmonella spp. ISOLATED FROM FOODS ASSOCIATED OR NOT WITH SALMONELLOSIS IN BRAZIL

Salmonella is the most common etiological agent of cases and outbreaks of foodborne diarrheal illnesses. The emergence and spread of Salmonella spp., which has become multi-drug resistant and potentially more pathogenic, have increased the concern with this pathogen. In this study, 237 Salmonella spp., associated or not with foodborne salmonellosis in Brazil, belonging mainly to serotype Enteritidis, were tested for antimicrobial susceptibility and the presence of the virulence genes spvC, invA, sefA and pefA. Of the isolates, 46.8% were sensitive to all antimicrobials and 51.9% were resistant to at least one antimicrobial agent. Resistance to more than one antimicrobial agent was observed in 10.5% of the strains. The highest rates of resistance were observed for streptomycin (35.9%) and nalidixic acid (16.9%). No strain was resistant to cefoxitin, cephalothin, cefotaxime, amikacin, ciprofloxacin and imipenem. The invA gene was detected in all strains. Genes spvC and pefA were found in 48.1% and 44.3% of strains, respectively. The gene sefA was detected in 31.6% of the strains and only among S. Enteritidis. Resistance and virulence determinants were detected in Salmonella strains belonging to several serotypes. The high rates of antibiotic-resistance in strains isolated from poultry products demonstrate the potential risk associated with the consumption of these products and the need to ensure good food hygiene practices from farm to table to reduce the spread of pathogens relevant to public health.

Sensitivity of Gomez-Nuñez boxes for the detection of household infestation with Panstrongylus megistus

Four methods for detecting household infestations with Panstrongylus megistus were compared: 1) manual collection; 2) collection after pyrethrum application; 3) search viable eggs; and 4) Gomez-Nuñez boxes. Manual collection was the most sensitive method (23% infested), followed by pyrethrum (21%), Gomez-Nuñez boxes (15%) and viable eggs (12%). About 10% of infested houses were positive exclusively on the Gomez-Nuñez box test. More over, 6 out of the 7 houses positive exclusively on the Gomez-Nuñez method were located in a recently sprayed area, where P. megistus density was low. Inspection of Gomez-Nuñez boxes at 12 weekspost-application was twice as effective as inspection at 6 weekspost-application. Triatomine feces was the most common evidencefor thepresence of P. megistus found within Gomez-Nuñez boxes. Gomez-Nuñez boxes area a useful adjunct to manual collection in detecting domestic infestations with P. megistus, especially in areas where bug densities are low. However, the utility of Gomez-Nuhez boxes must be weighed against the time and labor they require.

Increased osmotic sensitivity for antidiuretic response in chronic chagas' disease

The osmotic threshold for attaining the antidiuretic response to hypertonic saline infusion and Progressive dehydration was studied in 31 patients with the chronic form of Chagas' disease and 16 control patients. The chagasic patients exhibited enhanced osmoticsensitivity to the antidiuretic response. This was demonstrated by lower values of the increments in plasma osmolarity sufficient to induce a significant fall in water clearance, without alterations in the osmolar clearance or creatinine excretion. The time needed to attain the antidiuretic response was shorterfor chagasics in relation to normal subjects. The results suggest the existence of a disturbance in the fine control of osmoregulation in the chagasic patients. They are interpreted to be a consequence of the denervation in hypothalamic or extrahypothalamic areas that regulate the secretion of vasopressin in chronic Chagas' disease.

Low sensitivity of polymerase chain reaction for diagnosis of tuberculous meningitis in southeastern Brazil

Two polymerase chain reaction (PCR) protocols showed low sensitivity (36% and 53% for TB AMPLICOR and MPB64 nested PCR, respectively), when compared with classic microbiological methods (73% and 54% for Ziehl-Neelsen staining and culture, respectively), in the diagnosis of tuberculous meningitis in 91 patients in southeastern Brazil. Only three PCR-positive, microbiologically negative patients were found. Analysis of sequential cerebrospinal fluid samples by nested PCR detected Mycobacterium tuberculosis DNA up to 29 days after the introduction of antituberculosis chemotherapy.

Sensitivity of polymerase chain reaction for detection of known aliquots of Trypanosoma cruzi in the blood of mice: an in vitro study

To evaluate the sensitivity of polymerase chain reaction (PCR) to reveal known number of trypomastigote in the blood of mice, three separate experiments were done. First: To eight samples of 500mul of normal mice blood, one aliquot of 1, 2, 3, 4, 5, 10, and 50 trypomastigotes respectively, were added. Second and third: 10 aliquots with 1 and 10 with 2 trypomastigotes were added to samples of 500mul of normal mice blood. Positive control: 500mul of blood containing 100,000 trypomastigotes. For kDNA minicircles amplification by PCR the primers:S35 and S36 were used. PCR revealed products of 330 b.p in the positive controls. When only one sample with the aliquots of 1 or 2 trypomastigotes was examined, results were negative; results were positive with aliquots of 3 to 50 trypomastigotes. In the 2nd and 3rd experiments, 9/10 aliquots with one parasite and 9/10 with 2 trypomastigotes were positive revealing a high sensitivity of this reaction. In conclusion, the presence of one single parasite in 500mul of blood, is enough for a positive PCR. This method could be used as a complement to the various parasitological cure tests in treated mice, when low volumes of blood are individually examined.

Chemotherapeutic effects on larval stages of Schistosoma mansoni during infection and re-infection of mice

The sensitivity of the larval stages of Schistosoma mansoni to chemotherapy with praziquantel and oxamniquine was tested in mice during primary and secondary infections and after different intervals from cercarial exposure. Worm recovery by perfusion of the porto-mesenteric system, followed by counting and a morphometric study of the parasite, allowed the conclusion that the relative resistance of the larval stages of S. mansoni to schistosomicide drugs, demonstrated in primary infections, also persists when the host is already infected. This indicates that a therapeutic failure may result when an infected host is treated some time after being re-infected, because of the presence of migrating, drug-resistant, immature forms of the parasite.

Risky behavior regarding drug use and HIV infection: an Internet questionnaire coupled with short education texts for Portuguese speakers

Surveys of risky behavior relating to HIV/AIDS are generally made for groups at risk of infection, for which HIV/AIDS prevalence is usually expected to be higher than in the general population. Therefore, an educational homepage in Portuguese was created on the Internet to inform/ask internauts regarding knowledge and behavior. The internauts were classified as adolescents (13 to 25 years) and adults (>25 years). The number of STDs was reported as 1. 8 ± 2. 6 infections (range: 1 to 20 infections); 43% used condoms during sexual intercourse. Alcohol consumption was reported by 63% and illicit drug use by 32% (marijuana 24% and inhalants 15%). Among the adolescents, 31% did not classified alcohol as a drug. The adults more frequently reported homosexuality, anal intercourse and STDs, although the adolescents also presented high rates of risky behavior. These results show the need to reach out to internauts through better control strategies. Different types of strategies must be encouraged, in order to reach people that use this means of communication and entertainment.

Antituberculosis drug-induced hepatotoxicity: a comparison between patients with and without human immunodeficiency virus seropositivity

INTRODUCTION: The prevalence and risk factors for rifampin, isoniazid and pyrazinamide hepatotoxicity were evaluated in HIV-infected subjects and controls. METHODS: Patients with tuberculosis (30 HIV positive and 132 HIV negative), aged between 18 and 80 years-old, admitted to hospital in Brazil, from 2005 to 2007, were selected for this investigation. Three definitions of hepatotoxicity were used: I) a 3-fold increase in the lower limit of normal for alanine-aminotransferase (ALT); II) a 3-fold increase in the upper limit of normal (ULN) for ALT, and III) a 3-fold increase in the ULN for ALT plus a 2-fold increase in the ULN of total bilirubin. RESULTS: In groups with and without HIV infection the frequency of hepatotoxicity I was 77% and 46%, respectively (p < 0.01). Using hepatotoxicity II and III definitions no difference was observed in the occurrence of antituberculosis drug-induced hepatitis. Of the 17 patients with hepatotoxicity by definition III, 3 presented no side effects and treatment was well tolerated. In 8 (36.4%) out of 22, symptoms emerged and treatment was suspended. Alcohol abuse was related to hepatotoxicity only for definition I. CONCLUSIONS: Depending on the definition of drug-induced hepatitis, HIV infection may or may not be associated with hepatotoxicity. The impact that minor alterations in the definition had on the results was impressive. No death was related to drug-induced hepatotoxicity. The emergence of new symptoms after initiating antituberculosis therapy could not be attributed to hepatotoxicity in over one third of the cases.

Drug resistance of Mycobacterium tuberculosis strains in southern Brazil

INTRODUCTION: The aim of this work was to evaluate the prevalence of Mycobacterium tuberculosis (MT) strains with mutations that could result in resistance to the main drugs used in treatment in a region with one of the highest numbers of tuberculosis (TB) cases in southern Brazil. METHODS: Deoxyribonucleic acid (DNA) from 120 sputum samples from different patients suspicious of pulmonary tuberculosis who attended the Municipal Public Laboratory for Mycobacterium sp. diagnosis was directly amplified and analyzed by PCR-SSCP. The DNA was amplified in known hotspot mutation regions of the genes rpoB, ahpC, embB, katG, inhA, and pncA. RESULTS: The percentage of samples positive by culture was 9.2% (11/120); 5% (6/120) were positive by bacilloscopy and MT-PCR, and DNA fragments of the aforementioned resistance genes could be amplified from seven (7) of the eleven (11) samples with positive results, either by culture or PCR/bacilloscopy. All presented a SSCP pattern similar to a native, nonresistant genotype, with the ATCC strain 25177 as control, except for one sample (0.01%), which presented a SSCP profile demonstrating mutation at the embB gene. CONCLUSIONS: These results are consistent with the empirical observations by physicians treating TB patients in our region of a low occurrence of cases that are refractory to conventional treatment schemes, in contrast to other parts of the country. Continued surveillance, especially molecular, is essential to detect and monitor the outbreak of MT-resistant strains.

Evaluation of bacterial growth inhibition by mercaptopropionic acid in metallo-β-lactamase detection on multidrug-resistant Acinetobacter baumannii

INTRODUCTION: Metallo-β-lactamase (MBL) has been reported all over the world. METHODS: The inhibitory effect of mercaptopropionic acid (MPA) on bacterial growth was evaluated by comparison between disk diffusion and broth dilution methodology with determination of the minimum inhibitory concentration (MIC) for multidrug-resistant Acinetobacter baumanni strains. RESULTS: MPA significantly inhibited growth of the strains. CONCLUSIONS: The use of MPA can affect the results in phenotypic methods of MBL detection.