Benefit of amoxicillin in differentiating between TB suspects whose initial AFB sputum smears are negative.

SETTING: Out-patient dispensary in Conakry, Guinea, West Africa. OBJECTIVE: To differentiate between pulmonary tuberculosis (PTB) and non-PTB diseases among 204 acid-fast bacilli (AFB) smear-negative adult TB suspects. DESIGN: We derived scores from clinical, serological and radiological findings among PTB suspects aged > or = 15 years who, after having had three AFB-negative smears, were treated for 10 days with amoxicillin (AMX, 1.5 g/day). RESULTS: At the selected cut-off score from model 1 (clinical), sensitivity for PTB was 95%, specificity 40%, negative predictive value (NPV) 84%, and positive predictive value (PPV) 69%. Comparable values from model 2 (clinical + serological + radiological) were: sensitivity 99%, specificity 45%, NPV 97%, and PPV 71%. Results from AMX were better: sensitivity 92%, specificity 93%, NPV 94%, and PPV 91%. Of the 117 suspects who failed to respond clinically and radiographically to AMX and remained AFB smear-negative, 110 (94%) had PTB, confirmed either by positive culture (73 patients) or response to anti-tuberculosis treatment (37 patients). CONCLUSION: The clinical and radiographic response to AMX is better than derived scores at differentiating between PTB and non-PTB in TB suspects presenting to a dispensary in Guinea, a low HIV-seroprevalence country.     

Induced sputum improves the diagnosis of pulmonary tuberculosis in hospitalized patients in Gaborone, Botswana

SETTING: Low sensitivity of acid-fast bacilli (AFB) sputum smears and absence of productive cough are obstacles to the diagnosis of pulmonary tuberculosis (PTB) in hospitals that lack access to bronchoscopy. OBJECTIVES: To evaluate induced sputum, gastric content, blood and urine specimens to improve PTB diagnosis in patients not diagnosed by expectorated sputum AFB smears. DESIGN: Patients admitted to the medical wards of a large public hospital in Gaborone, Botswana, were prospectively enrolled if they had symptoms consistent with PTB, an abnormal chest radiograph, were treated empirically with anti-tuberculosis chemotherapy or had no improvement on antibiotics, and had a non-productive cough or AFB smear-negative sputum. Induced sputum was stained for AFB and Mycobacterium tuberculosis cultures were performed on induced sputum, gastric contents, urine and blood. RESULTS: Of 140 patients meeting the enrollment criteria, 113 (81%) were human immunodeficiency virus (HIV) positive. Fifty-seven (41%) had PTB based on positive cultures from one or more sites, including 48 (84%) from induced sputum, 17 (30%) urine, 13 (23%) gastric contents and 7 (12%) blood. AFB smears were positive in only 18 (32%) culture-proven PTB cases. CONCLUSION: Induced sputum cultures greatly enhanced M. tuberculosis detection in patients with a high prevalence of HIV/AIDS in a hospital without access to bronchoscopy.     

Risk factors for negative sputum acid-fast bacilli smears in pulmonary tuberculosis: results from Dakar, Senegal, a city with low HIV seroprevalence.

SETTING: Two teaching hospitals in Dakar, Senegal, a West African country with a low prevalence of human immunodeficiency virus (HIV) infection. OBJECTIVE: To determine whether patients with HIV-associated pulmonary tuberculosis have fewer acid-fast bacilli (AFB) in their sputum as assessed by routine microscopy, and to correlate the findings with systematically obtained clinical, radiographic and laboratory variables. DESIGN: Prospective study from November 1995 to October 1996 of 450 consecutive patients diagnosed with pulmonary tuberculosis. RESULTS: Tuberculosis was diagnosed in 380 patients (84.4%) by positive bacteriology, in 61 (13.6%) by a favorable response to anti-tuberculosis chemotherapy, and in nine (2.0%) by the presence of a miliary radiographic pattern. Forty (8.9%) patients were HIV-seropositive. AFB-negative smears were found in 14/40 (35.0%) of the HIV-seropositive patients with pulmonary tuberculosis compared with 71/410 (17.3%) of the seronegative patients (risk ratio [RR] = 2.02, 95% confidence interval [CI] 1.26-3.24, P = 0.01). Multivariate analysis revealed that AFB smear negativity was associated with absence of cavitation (P = 0.002), lack of cough (P = 0.005), the presence of HIV seropositivity (P = 0.02), a CD4+ cell count above 200/mm3 (P = 0.02), and age over 40 years (P = 0.03). CONCLUSIONS: Compared with HIV-seronegative patients with pulmonary tuberculosis, seropositive patients in Dakar, Senegal, are more likely to have negative sputum-AFB smears. This phenomenon has now been observed in seven of eight sub-Saharan African countries with varying HIV seroprevalence from which reports are available.     

The diagnosis of smear-negative pulmonary tuberculosis: the practice of sputum smear examination in Malawi.

SETTING: Forty hospitals in Malawi (3 central, 22 district and 15 mission) performing smear microscopy and registering tuberculosis patients. OBJECTIVE: To determine, in patients aged 15 years or above, 1) the proportion with smear-negative pulmonary tuberculosis (PTB) who had sputum smears examined, 2) the number of sputum smears examined per patient, and 3) the proportion of patients registered with smear-positive and smear-negative PTB. DESIGN: Data collection during three 6-month periods, from January 1997 to June 1998, using tuberculosis registers, laboratory sputum registers and quarterly reports. RESULTS: Of 6301 smear-negative PTB patients, 84% had sputum smears examined, the rate increasing from 76% in January-June 1997, to 85% in July-December 1997, to 89% in January-June 1998. Of patients who submitted sputum (where the number of smears was recorded), 99% had two or more smears examined and 93% had three smears examined. In district and mission hospitals performance improved over time, while in central hospitals results were more variable. During the same 18-month period 21 422 patients aged 15 years or more were registered with PTB: 59% with smear-positive PTB and 41% with smear-negative PTB; this pattern was similar in each 6-month period. CONCLUSION: The study suggests that it is reasonable to aim for a target of 90% or more of smear-negative PTB patients having sputum smears examined.     

Clinical diagnosis of smear-negative pulmonary tuberculosis: an audit of diagnostic practice in hospitals in Malawi.

SETTING: Thirty-seven hospitals in Malawi. OBJECTIVE: To audit the hospital practice of clinically diagnosing adults with smear-negative pulmonary tuberculosis (PTB). DESIGN: A cross-sectional survey of adults aged 15 years or above who were registered and receiving inpatient treatment for smear-negative PTB. An assessment of each patient was carried out to determine 1) the number of recommended diagnostic guidelines (cough >3 weeks, no response to antibiotics, negative sputum smears and a chest radiograph compatible with PTB) used by hospital staff in making the diagnosis of PTB, and 2) whether the clinical diagnosis of smear-negative PTB was correct according to criteria set by the study. RESULTS: There were 259 patients, 127 men and 132 women, with a mean age of 37 years; 93% had a cough >3 weeks, 95% had received one or more courses of antibiotics, 92% had submitted sputum samples for smear examination and 97% had chest radiographs performed. In 148 (57%) patients, all four diagnostic guidelines were used, and in 238 (92%) patients three or more were used. The diagnosis of smear-negative PTB was considered correct by study criteria in 203 (78%) patients. In the remainder, 22 (8%) were considered to have extrapulmonary TB and 34 (14%) another diagnosis. CONCLUSION: Hospital practices in the diagnosis of smear-negative PTB are reasonable, although there is room for improvement with in-service training and regular audits of practice.     

Comparison of sputum induction with fiberoptic bronchoscopy in the diagnosis of tuberculosis: experience at an acquired immune deficiency syndrome reference center in Rio de Janeiro, Brazil

Many patients with suspected pulmonary tuberculosis (PTB) do not produce sputum spontaneously or are smear-negative for acid-fast bacilli (AFB). We prospectively compared the yield of sputum induction (SI) and fiberoptic bronchoscopy with bronchoalveolar lavage (BAL) for the diagnosis of PTB in a region with a high prevalence of tuberculosis and human immunodeficiency virus (HIV) infection. Fifty seven percent (143 of 251) of patients had diagnoses of PTB, of whom 17% (25 of 143) were HIV seropositive. There were no significant differences in the yields of AFB smears or cultures whether obtained via SI or BAL. Among 207 HIV-seronegative patients, the AFB smear and mycobacterial culture results from specimens obtained by SI and BAL were in agreement in 97% (202 of 207) (kappa test = 0.92) and 90% (186 of 207) (kappa test = 0.78), respectively. Among HIV-seropositive patients the agreements between AFB smear and culture results for SI and BAL specimens were 98% (43 of 44) (kappa test = 0.93) and 86% (38 of 44) (kappa test = 0.69), respectively. We conclude that SI is a safe procedure with a high diagnostic yield and high agreement with the results of fiberoptic bronchoscopy for the diagnosis of PTB in both HIV-seronegative and HIV-seropositive patients.     

Fiberoptic bronchoscopy for the rapid diagnosis of smear-negative pulmonary tuberculosis

ABSTRACT: BACKGROUND: This study was aimed to investigate the diagnostic value of fiberoptic bronchoscopy (FOB) with chest high-resolution computed tomography (HRCT) for the rapid diagnosis of active pulmonary tuberculosis (PTB) in patients suspected of PTB but found to have a negative sputum acid-fast bacilli (AFB) smear. METHODS: We evaluated the diagnostic accuracy of results from FOB and HRCT in 126 patients at Gangnam Severance Hospital (Seoul, Korea) who were suspected of having PTB. RESULTS: Of 126 patients who had negative sputum AFB smears but were suspected of having PTB, 54 patients were confirmed as having active PTB. Hemoptysis was negatively correlated with active PTB. Tree-in-bud appearance on HRCT was significantly associated with active PTB. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of FOB alone was 75.9%, 97.2%, 95.3%, and 84.3%, respectively, for the rapid diagnosis of active PTB. The combination of FOB and HRCT improved the sensitivity to 96.3% and the NPV to 96.2%. CONCLUSIONS: FOB is a useful tool in the rapid diagnosis of active PTB with a high sensitivity, specificity, PPV and NPV in sputum smear-negative PTB-suspected patients. HRCT improves the sensitivity of FOB when used in combination with FOB in sputum smear-negative patients suspected of having PTB.     

A preliminary report on pulmonary tuberculosis in patient travelers to a rural hospital of South India

BACKGROUND: Occurrence of pulmonary tuberculosis (PTB) among patient travelers in private rural hospitals are often unknown. OBJECTIVES: The aims of the study were to know the occurrence of PTB among patient travelers visiting PES hospital and to create an information and awareness in the establishment of revised national tuberculosis control program (RNTCP) in PES hospital. PATIENT AND METHODS: Adult patients (18-49yr) with TB-like chest symptoms traveling from different regions to Kuppam were included. Children, pregnant women and critically ill were excluded. Between January-December 2004, 372 such patients visited PES hospital. Two consecutive sputum samples were screened for AFB detection by Ziehl-Neelsen. Presence of AFB in both the smears was considered smear positive TB. Negative smears with X-ray abnormality was considered smear-negative TB. Anti-tubercular drugs were prescribed for TB patients. RESULTS: Of 372 patients visited, 29% were diagnosed as TB. Smear-positive and smear-negative TB were 16.6% and 12.3%, respectively. TB among females (31/113) and males (77/259) were 27.4% and 29.7%, respectively. The peak input of patients was in the months of May (53), March (48) and December (35). CONCLUSION: There is an urgent need for establishment of RNTCP in PES hospital.     

Clinical diagnosis of smear-negative pulmonary tuberculosis in low-income countries: the current evidence

Sputum smear examination for acid-fast bacilli (AFB) can diagnose up to 50-60% of cases of pulmonary tuberculosis in well-equipped laboratories. In low-income countries, poor access to high-quality microscopy services contributes to even lower rates of AFB detection. Furthermore, in countries with high prevalence of both pulmonary tuberculosis and HIV infection, the detection rate is even lower owing to the paucibacillary nature of pulmonary tuberculosis in patients with HIV infection. In the absence of positive sputum smears for AFB, at primary care level, most cases of pulmonary tuberculosis are diagnosed on the basis of clinical and radiological indicators. This review aims to evaluate various criteria, algorithms, scoring systems, and clinical indicators used in low-income countries in the diagnosis of pulmonary tuberculosis in people with suspected tuberculosis but repeated negative sputum smears. Several algorithms and clinical scoring systems based on local epidemiology have been developed to predict smear-negative tuberculosis. Few of these have been validated within the local context. However, in areas where smear-negative tuberculosis poses a major public-health problem, these algorithms may be useful to national tuberculosis programmes by providing a starting point for development their own context-specific diagnostic guidelines.     

Identifying pulmonary tuberculosis in patients with negative sputum smear results

BACKGROUND: Clinicians need to decide whether to begin empiric therapy for patients who are suspected of having tuberculosis (TB) but have negative sputum smear results. Culture results may take weeks, and delaying treatment may allow further transmission of disease. Study objective: To identify the clinical, demographic, and radiographic characteristics that identify smear-negative patients who have TB, and to create a TB prediction rule. DESIGN: Retrospective chart review. SETTING: University-affiliated public hospital in San Francisco, CA, between 1993 and 1998. PATIENTS: Forty-seven patients with TB and 141 control patients who were hospitalized with a suspicion of pulmonary TB; all had negative sputum smear results. Measurements and results: Demographic, clinical, and radiographic variables were determined by chart review. In multivariate analysis, a positive tuberculin skin test result (odds ratio [OR], 4.8; 95% confidence interval [CI], 2.0 to 11.9) was independently associated with an increased risk of a positive TB culture finding. A radiographic pattern not typical of pulmonary tuberculosis (OR, 0.3; 95% CI, 0.1 to 0.7) and expectoration with cough (OR, 0.3; 95% CI, 0.1 to 0.6) were predictive of a decreased risk. An interaction between HIV seropositivity and mediastinal lymphadenopathy on the chest radiograph was also associated with a positive TB culture result (OR, 7.2; 95% CI, 1.4 to 36.0). The TB prediction score (TPS) was created with widely ranging likelihood ratios that could affect the posterior probability of TB by 30-fold. CONCLUSION: The TPS put into context with the overall prevalence of TB in a given area may help clinicians decide if a patient with negative sputum smear results should start empiric antituberculous therapy or wait for culture results. These results need prospective validation.     

Time between sputum examination and treatment in patients with smear-negative pulmonary tuberculosis.

The time between sputum examination and commencement of treatment in patients registered with smear-negative pulmonary tuberculosis (PTB) in four hospitals in Malawi was investigated. Information was obtained in 701 of 887 patients who were registered over a 12-month period between 1997 and 1998: 86% were started on treatment within 3 weeks of sputum examination, 14% were started after a 3-week interval and 6% after a 6-week interval. Such delays are unacceptable, for a number of reasons. Recommendations will go to programme staff to repeat sputum examination in PTB suspects with an abnormal chest radiograph whose negative sputum smears were examined more than 3 weeks previously.     

Occurrence of Pneumocystis carinii in HIV-positive patients with suspected pulmonary tuberculosis in Ethiopia

OBJECTIVE: To investigate the prevalence of Pneumocystis carinii in consecutive HIV-positive patients with suspected pulmonary tuberculosis (PTB) attending a university hospital in Ethiopia. METHODS: A PCR for P. carinii and an indirect immunoflorescence (IF) assay were performed on expectorated sputum samples from: 119 HIV-1-positive patients with negative smears and sputum cultures for Mycobacterium tuberculosis; 96 HIV-1-positive patients with culture-verified PTB; and 97 HIV-negative patients with negative mycobacterial cultures and 72 HIV-negative patients with culture-verified PTB, serving as controls. Outcome of PCR and IF were compared with the chest radiographic (CXR) and initial clinical diagnosis. RESULTS: In the HIV+PTB- group, P. carinii was found in 10.9% by IF, 8.4% by single PCR (sPCR) and 30.3% by nested PCR (nPCR). In the HIV+PTB+ group, 3.1% were P. carinii positive by IF and sPCR and 13.5% by nPCR. All IF- and sPCR-positive samples were nPCR positive. In the HIV-PTB+ and HIV-PTB- groups, 4.2% and 3.1% were nPCR positive, respectively. Six out of eight HIV+PTB- patients with CXR suggesting P. carinii pneumonia (PCP) were IF and/or nPCR positive for P. carinii. In the IF-positive and nested PCR-positive HIV+PTB- patients more than one-third were interpreted as PTB by CXR whereas only one patient was diagnosed with clinical PCP. CONCLUSIONS: P. carinii is prevalent in HIV-positive PTB suspects, suggesting that PCP may be an important, but not well recognized, differential diagnosis. Our findings have implications for treatment and primary prophylaxis for PCP in Ethiopia.     

The prevalence of pulmonary parenchymal tuberculosis in patients with tuberculous pleuritis

STUDY OBJECTIVE: To examine the prevalence and characteristics of parenchymal tuberculous pleuritis in adult patients. DESIGN: Prospective cohort study. SETTING: Three hospitals affiliated with Seoul National University in South Korea. PATIENTS: All patients > 15 years old with a diagnosis of tuberculous pleuritis were enrolled prospectively between January 1, 2004, and October 31, 2004. INTERVENTIONS: Diagnostic thoracocentesis and CT of the chest were done for each patient. Acid-fast bacilli (AFB) smears and cultures for Mycobacterium tuberculosis were requested if patients produced any sputum. A board-certified radiologist reviewed the chest radiographs for the presence and characteristics of any lesions. MEASUREMENTS AND RESULTS: One hundred six patients with tuberculous pleuritis were enrolled (median age, 53 years; range 16 to 89 years). Among them, 33 patients (31%) had sputum or bronchial washing findings positive for AFB smears or for M tuberculosis by culture. Lung parenchymal lesions were observed in 91 of the patients (86%) using chest CT; 39 patients (37%) with parenchymal lesions had radiographic characteristics of active pulmonary tuberculosis. In total, 62 patients (59%) had bacteriologically or radiographically active pulmonary tuberculosis. In addition, 78 patients (74%) had features of reactivated pulmonary tuberculosis. CONCLUSIONS: Lung parenchymal lesions were more common in this series of patients with tuberculous pleuritis than has been reported in previous studies. The patients mostly had radiographic features of reactivated, rather than primary, tuberculosis.     

Mortality rates and recurrent rates of tuberculosis in patients with smear-negative pulmonary tuberculosis and tuberculous pleural effusion who have completed treatment.

SETTING: Queen Elizabeth Central Hospital, Blantyre, and Zomba Central Hospital, Zomba, Malawi. OBJECTIVE: To follow-up human immunodeficiency virus (HIV) seropositive and HIV-seronegative patients with smear-negative pulmonary tuberculosis (PTB) and pleural TB who had completed treatment with two different regimens in Blantyre and Zomba, and to assess rates of mortality and recurrent TB. DESIGN: Patients with smear-negative and pleural TB who had completed 8 months ambulatory treatment in Blantyre or 12 months standard treatment in Zomba and who were smear and culture negative for acid-fast bacilli at the completion of treatment were actively followed every 4 months for a total of 20 months. RESULTS: Of 248 patients, 150 with smear-negative PTB and 98 with pleural TB, who completed treatment and were enrolled, 205 (83%) were HIV-positive. At 20 months, 145 (58%) patients were alive, 85 (34%) had died and 18 (7%) had transferred out of the district. The mortality rate was 25.7 per 100 person-years, with increased rates strongly associated with HIV infection and age >45 years. Forty-nine patients developed recurrent TB. The recurrence rate of TB was 16.1 per 100 person-years, with increased rates strongly associated with HIV infection, having smear-negative PTB and having received 'standard treatment'. CONCLUSION: High rates of mortality and recurrent TB were found in patients with smear-negative PTB and pleural effusion during 20 months of follow-up. TB programmes in sub-Saharan Africa must consider appropriate interventions, such as co-trimoxazole and secondary isoniazid prophylaxis, to reduce these adverse outcomes.     

Diagnostic value of gastric aspirate smear and polymerase chain reaction in smear-negative pulmonary tuberculosis

OBJECTIVE: The aim of this study was to determine the validity of acid-fast bacilli (AFB) smear and polymerase chain reaction (PCR) from gastric aspirates for the diagnosis of smear-negative pulmonary tuberculosis. METHODOLOGY: A cross-sectional study was conducted in a university hospital. One hundred and nine patients with suspected pulmonary tuberculosis in whom either sputum smears were negative or who were not producing sputum were recruited to the study. All patients underwent gastric aspiration after an overnight fast followed by standard fibreoptic bronchoscopy. Specimens were subjected to AFB smear, culture, and pathological examination. PCR was performed on culture filtrate after 1 week of incubation. RESULTS: Eight patients did not complete the follow-up schedule. Of the 101 patients with final outcomes, a diagnosis of pulmonary tuberculosis from microbiological evidence was established in 54 patients. The gastric aspirate smear, PCR, or either one of them was positive in 34, 30, and 39 tuberculosis patients, respectively. There were 13 false positive smears from 47 non-tuberculosis patients, with five resulting from non-tuberculous mycobacteria (NTM). The PCR was falsely positive in eight patients, five of whom had previous histories of tuberculosis. The overall sensitivity, specificity, positive predictive value, and negative predictive value of gastric aspirate examination by combined smear and PCR were 72, 58, 66, and 64%, respectively. CONCLUSIONS: Gastric aspiration is a useful tool for the diagnosis of smear-negative pulmonary tuberculosis warranting institution of antituberculosis treatment. Interpretation of the results should be cautious in those who have had tuberculosis in the past or who have been at risk for acquisition of NTM.     

What causes smear-negative pulmonary tuberculosis in Malawi, an area of high HIV seroprevalence?

SETTING: The Central Hospital and the District Tuberculosis (TB) Registry in Lilongwe, the capital of Malawi. In this setting smear-negative pulmonary tuberculosis (PTB) is diagnosed using clinical and radiographic criteria for TB, and mycobacterial cultures are not routinely available. OBJECTIVE: To determine the proportion of patients being registered for smear-negative PTB treatment in Lilongwe who have TB that can be confirmed microbiologically. DESIGN: Prospective cohort study of patients about to start treatment under operational conditions for smear-negative PTB in Lilongwe between October 1997 and June 1998. Patients referred to the study team underwent a detailed clinical re-assessment, testing for human immunodeficiency virus (HIV), repeat sputum smear microscopy for acid-fast bacilli and mycobacterial cultures of sputum and blood. Bronchoscopy and bronchoalveolar lavage (BAL) were performed and BAL fluid was examined for TB, Pneumocystis carinii and other fungi. RESULTS: Of 352 smear-negative PTB suspects assessed, the diagnosis of TB was confirmed in 137 (39%) cases. Eighty-nine per cent of patients assessed were HIV-positive, of whom 81% met the expanded case definition for the acquired immune-deficiency syndrome (AIDS). CONCLUSION: TB was the most commonly confirmed diagnosis amongst patients about to start treatment for smear-negative PTB in an area of high background HIV seroprevalence.     

Pulmonary TB and NTM lung disease: comparison of characteristics in patients with AFB smear-positive sputum.

OBJECTIVE: To compare the clinical and radiographic features of pulmonary tuberculosis (PTB) and non-tuberculous mycobacteria (NTM) lung disease in patients with acid-fast bacilli (AFB) positive sputum specimens. DESIGN: The initial clinical and radiographic features of 229 PTB patients were compared with those of 70 patients with NTM lung disease. The most commonly involved organisms in the NTM lung disease cases were Mycobacterium avium complex (n = 38, 54%) and M. abscessus (n = 26, 37%). RESULTS: Clinical and radiographic findings that were more common in patients with NTM lung disease than in PTB patients were: older age (P < 0.001), non-smoker (P < 0.001), history of previous TB treatment (P < 0.001), absence of pleural effusion (P = 0.017), involvement of middle and/or lower lung zones (P = 0.007), and bilateral disease (P = 0.005). Multivariate analysis showed that older age (> or = 40 years), non-smoker, previous TB treatment, absence of pleural effusion and involvement of middle and/or lower lung zones were significant independent predictors for NTM lung disease. CONCLUSIONS: There is considerable overlap in the clinical and radiographic appearances of PTB and NTM lung disease. The isolation and identification of causative organisms are mandatory for a correct diagnosis in patients with AFB-positive sputum specimens.     

High-resolution CT findings in patients with pulmonary tuberculosis: correlation with the degree of smear positivity

BACKGROUND: There are data about the relationship between morphologic findings on high-resolution computed tomography (HRCT) and the number of acid-fast bacilli (AFB) on sputum smears in patients with pulmonary tuberculosis (PTB). It was also shown that existence of cavities and airspace consolidation might be related to smear positivity in PTB patients. However, there is no study suggesting a relationship between AFB on sputum smears and radiologic extent of disease based on HRCT findings. AIM: In this study, we investigated a relationship between the degree of smear positivity and radiologic extent of disease based on HRCT findings and, the degree of smear positivity and different pulmonary parenchymal changes on HRCTs of the PTB patients. METHODS: Sixty-one male patients with PTB (mean age: 22+/-3.2) were included into the study. HRCT images were assessed for patterns, distribution, and profusion of pulmonary abnormalities. Dividing the lungs into 3 zones, profusion of abnormalities was assessed. A profusion score was given. Patients were divided as smear positive and smear negative and compared for the scores of HRCT findings. Smear-positive patients were divided into 4 groups as per grading of the sputum AFB smear: group I (sputum 1+), group II (sputum 2+), group III (sputum 3+), and group IV (sputum 4+). Correlations were investigated between the degree of smear positivity and the scores of HRCT findings. RESULTS: A significant correlation between radiologic extent of the disease based on HRCT and the degree of smear positivity was found (r=0.63, P=0.0001). There were also significant correlations between the degree of smear positivity and the scores of different HRCT findings. Nodule, cavity, and bronchial lesions are the most important contributors of the predictive properties of the total score. There was significant differences for the scores of HRCT findings between smear-positive and smear-negative patients. CONCLUSIONS: Our study suggests that radiologic extent of disease based on HRCT findings in patients with PTB correlated with the degree of smear positivity. Different HRCT findings such as nodule, cavitation, ground-glass opacity, consolidation, and bronchial lesion are significantly associated with smear-positive PTB. Particularly, nodules, cavities, and bronchial lesions might be predictors of smear positivity in patients with PTB. This study also suggests that the thickness of cavity wall and the distance of cavity from central airways might be related to the degree of smear positivity.     

Use of the amplified mycobacterium tuberculosis direct test in a public health laboratory: test performance and impact on clinical care

BACKGROUND: The Amplified Mycobacterium tuberculosis Direct Test (MTD; Gen-Probe; San Diego, CA) is a nucleic-acid amplification test for rapid pulmonary tuberculosis (PTB) diagnosis. In a routine public health setting, test accuracy and impact on clinical decisions are unknown. METHODS: Retrospectively, we evaluated MTD accuracy and impact on clinical decisions in a public health setting. To estimate MTD accuracy, mycobacterial culture was used as the "gold standard." To evaluate MTD impact on clinical decisions, concordance of clinician presumptive diagnosis (at time of MTD and smear availability) and definitive diagnosis, and duration of nonindicated tuberculosis therapy were determined for smear-positive PTB suspects in a period of MTD availability (MTD group) and a prior period of MTD nonavailability (non-MTD group). RESULTS: A total of 1,151 respiratory specimens from 638 PTB suspects were analyzed. MTD sensitivity, specificity, positive predictive value, and negative predictive value were 91.7%, 98.7%, 96.7%, and 96.5% overall, respectively; and 98.7%, 97.8%, 98.7%, and 97.8% for smear-positive patients; and 62.2%, 98.9%, 85.2%, and 96.1% for smear-negative patients. In the MTD group, concordance between definitive and clinician presumptive diagnoses was 78% (95% confidence interval [CI], 64 to 88%), similar to that for the non-MTD group (79%; 95% CI, 68.4 to 89.6%). However, concordance between definitive diagnosis and the MTD test was 98% (95% CI, 94.1 to 100%). Median duration of nonindicated tuberculosis treatment was 6 days for the MTD group vs 31 days for the non-MTD group (p = 0.002). CONCLUSION: In this public health setting, MTD was accurate and rapidly detected more than half of the smear-negative PTB cases. For smear-positive PTB suspects, MTD had excellent concordance with definitive diagnosis, but clinicians often inappropriately initiated TB therapy despite a negative MTD result.     

Pneumocystis jiroveci pneumonia and other pulmonary infections in TB smear-negative HIV-positive patients with atypical chest X-ray in Ethiopia

Pneumocystis pneumonia (PCP) has been considered a rare disease in sub-Saharan Africa. However, a rising prevalence has been noted recently. The objective of this study was to determine the relative prevalence of PCP and other pulmonary opportunistic diseases in patients infected with HIV in Ethiopia. 131 consecutive patients with respiratory symptoms and atypical chest X-ray, who were sputum smear-negative for AFB and seroreactive for HIV, underwent clinical evaluation and investigation for Pneumocystis jiroveci and Mycobacterium tuberculosis from sputum and bronchoalveolar lavage (BAL), and fungal and bacterial pathogens from BAL alone. Bacterial infections, Pneumocystis pneumonia (PCP) and pulmonary tuberculosis (PTB) occurred in 44 (33.6%), 39 (29.7%) and 31 (23.7%) patients, respectively. Pulmonary Kaposi sarcoma and non-specific interstitial pneumonitis occurred in 4 patients each. In a multivariate regression model, predictors of PCP were typical chest X-ray and low CD4 count while purulent sputum predicted bacterial infection. The sensitivity of physicians and chest X-ray diagnosis was particularly low for PTB and bacterial infections. We conclude that chronic bacterial infection and Pneumocystis pneumonia are important differential diagnoses in HIV-infected, smear-negative PTB patients presenting with atypical chest X-ray. We therefore need to escalate the use of preventive and highly active antiretroviral (HAART) treatment in order to prevent a PCP epidemic.