Negative Acid-fast Bacilli Research Articles

Diagnostic contribution of gastric and bronchial lavage examinations in cases suggestive of pulmonary tuberculosis.

We assessed whether acid fast bacilli (AFB) determination in gastric lavage (GL) and bronchial lavage (BL) contributes to diagnosis in cases radiologically suggestive of pulmonary tuberculosis but with either negative AFB in sputum or the inability to expectorate sputum. Of 129 cases recruited for the study, 22 were excluded due to evaluation as inactive disease or non-tuberculosis disease. The remaining 107 cases were evaluated in 2 groups. Group A consisted of 49 patients that could not expectorate sputum and from whom GL was obtained. In group B, BL was performed in 58 patients that had negative sputum smear. Smear positivity was 61.2% (30/49) and culture positivity was 30.6% (15/49) in group A, 51.7% (30/58) and 81% (47/58), respectively, in group B. Thirteen cases, in whom AFB could not be detected microbiologically but who were radiologically strongly suggestive of tuberculosis, were regarded as tuberculosis according to "from treatment to diagnosis" criteria. In conclusion, detection of AFB positivity in the diagnosis of tuberculosis is important in terms of early initiation of treatment and detection of resistant bacilli. Therefore, we suggest that it would be helpful to obtain GL in cases where the patient is unable to expectorate sputum, and perform BL in cases with negative sputum smear.

Tuberculosis in the upper aerodigestive tract and human immunodeficiency virus coinfections.

To describe the clinical manifestations of tuberculosis in the upper aerodigestive tract. Retrospective chart analysis. Srinagarind Hospital, Department of Otolaryngology, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand. A review of medical records of patients diagnosed with mycobacterial infection of the upper aerodigestive tract between January 1991 and December 2000. Presenting symptoms, clinical findings, pathologic findings, pulmonary involvement, and outcome of treatment. Forty-five patients presented with upper aerodigestive tract tuberculosis. The nasopharynx was involved in 23 patients, the larynx in 16, the tonsils in 6, and the soft palate in 1. One patient had tuberculous infections in both the nasopharynx and tonsils. The mean duration of symptoms before diagnosis was 2.1 months. The pathologic findings included caseous granuloma and/or positive acid-fast bacilli (AFB) in 39 cases and chronic granulomatous inflammation with negative AFB in 6 cases. Pulmonary tuberculosis was found in 19 of the 36 patients who underwent radiography. A positive serologic test for human immunodeficiency virus (HIV) infection was found in 4 of 26 patients. These 26 patients, who received a full course of treatment, responded well. The most common site of tuberculosis in the head and neck involved the cervical lymph nodes and nasopharynx. Upper aerodigestive tract tuberculosis is difficult to differentiate from carcinoma; thus, tissue biopsy is necessary for a definite diagnosis. Chest radiography and screening for HIV infection are recommended in all patients with upper aerodigestive tract tuberculosis.

Uterine granulomas: clinical and pathologic features.

We retrospectively studied the clinical and pathologic features of uterine granulomas over a 10-year period. Granulomas were detected in 30 women, 22 to 81 years old, in the cervix (n = 12/1,090 cervical specimens; 1.1%) or uterine corpus (n = 18/12,000 uterine specimens; 0.15%). They were discovered during evaluation of abnormal bleeding, cytologic specimens, or other gynecologic conditions. None of the patients had constitutional symptoms. These granulomas were often focal (n = 25 [83%]), exhibiting features of foreign body-type (n = 17 [68%]); or they were diffuse (n = 5 [17%]), all with negative acid-fast bacilli or fungal stains and sometimes necrotizing (2 [40%]). Focal granulomas were highly associated with a preceding biopsy or surgery (22/25 vs 14/53 age-matched control subjects). Follow-up of 28 patients (median, 16 months) showed that 27 remained healthy; only 1 patient developed generalized lesions consistent with sarcoidosis 16 months later Uterine granulomas are rare. They are eitherfocal, related to previous biopsy or surgery, or diffuse, usually representing local reaction without an obvious cause. Association with infection or systemic granulomatous disorders is uncommon.

Preventing nosocomial transmission of pulmonary tuberculosis: when may isolation be discontinued for patients with suspected tuberculosis?

The Centers for Disease Control and Prevention and the American Thoracic Society recommend obtaining cultures of at least three sputum specimens for acid-fast bacilli (AFB) from patients in whom tuberculosis (TB) is suspected. On the basis of this, most hospitals isolate patients with suspected TB for 3 days or more until three smear (not culture) results are negative. Our objective was to evaluate the predictive value and sensitivity of these smears. Observational study. Four urban medical centers. The posttest probability of TB given sequential negative AFB smears from 274 patients isolated for suspected TB and the sensitivity of sequential AFB smears from 209 patients with positive results on culture for pulmonary TB were measured. The posttest probabilities of having TB given one, two, and three negative AFB smears were low: 1.1% (3 of 265; 95% confidence interval [CI95], 0.23% to 3.27%), 0.4% (1 of 262; CI95 0% to 2.1%), and 0% (0 of 260; CI95, 0% to 1.4%), respectively. Among the 209 patients with positive results on culture for pulmonary TB, 169 (81%) had an expectorated sputum specimen sent, of which 91 (54%) were positive for AFB. Forty (24%) of the 169 patients had a second expectorated sputum specimen sent after the results of the first specimen were negative; only 6 (15%) of these had positive AFB smears. None of the 10 patients in whom the first two expectorated sputum samples yielded an AFB smear without an organism had a third AFB smear that was positive. Unless there is high clinical suspicion of pulmonary TB in a specific patient, the use of three AFB smears on expectorated sputa is a rational approach to discontinuing isolation for patients with suspected TB.

Integration of tuberculosis screening at an HIV voluntary counselling and testing centre in Haiti.

To describe the integration of tuberculosis screening into the activities of an HIV voluntary counselling and testing (VCT) centre in a country with endemic tuberculosis. An HIV VCT centre in Port au Prince, Haiti. All patients presenting for HIV VCT who reported cough received same-day evaluation for active tuberculosis. Of the 1327 adults presenting to the centre for the first time between January and April 1997, 263 (20%) reported cough and of these 241 (92%) were evaluated. Of the 241 patients evaluated for cough, 76 (32%) were diagnosed with pulmonary tuberculosis. Of the 76 patients diagnosed with pulmonary tuberculosis, 28 (37%) had a positive smear for acid-fast bacilli (AFB), 14 (18%) had a negative AFB smear but a positive sputum culture for Mycobacterium tuberculosis, and 34 (45%) had culture-negative tuberculosis. Also, 31 out of 241 (13%) VCT clients evaluated for cough were diagnosed with bacterial pneumonia. This report confirms that in areas with a high HIV and tuberculosis prevalence, a high proportion of VCT clients have active pulmonary tuberculosis. The integration of tuberculosis screening offers several benefits, including the diagnosis and treatment of large numbers of individuals with tuberculosis, a decreased risk of nosocomial tuberculosis transmission, and the opportunity to provide tuberculosis prophylaxis to HIV-positive patients in whom tuberculosis has been excluded. Future studies are needed to determine the cost-effectiveness of integrated tuberculosis and HIV VCT services, and whether integration should be recommended in all countries with high HIV and tuberculosis rates.

Occupationally Acquired Infections A Timely Reminder

Healthcare workers (HCWs) are known to be at risk for contracting an infection from a patient or from a patient specimen.1 It might be presumed that no one would be more aware of this risk than HCWs themselves; yet, these risks often are minimized or even ignored by HCWs who perhaps through long exposure to such risks have become immune to concern albeit not to infection. It is thus useful for HCWs to be reminded of these risks from time to time, so that we do not become too complacent. The January 2001 issue of Infection Control and Hospital Epidemiology begins the new year, and indeed the new millennium, with a timely reminder that occupationally acquired infections continue to be a very real risk for HCWs. This reminder is in the form of three reports that aptly illustrate the ongoing problems associated with such infections in HCWs. In this editorial, I will comment briefly on each of these reports, discuss the salient points, and suggest an approach that would avoid, or at least curtail, some of these problems in the future. The first report, by Obasanjo et al, is entitled “An Outbreak of Scabies in a Teaching Hospital: Lessons Learned” and describes a large outbreak of scabies in an acute-care urban hospital.2 Overall, 773 HCWs and 204 patients were exposed to an individual (HCW or patient) with scabies and required prophylaxis or treatment. Of these, 113 (15%) of 773 HCWs and 82 (40%) of 204 patients had symptoms or developed a rash consistent with scabies. This outbreak resulted in over $50,000 in direct expenses and almost $20,000 in person-hours lost due to sick leave. The effect of this outbreak on staff morale was far greater than its financial impact. The second report, by D’Agata et al, is entitled “Nosocomial Transmission of Mycobacterium tuberculosis from an Extrapulmonary Site” and describes nosocomial transmission of tuberculosis from a genitourinary site.3 This elderly patient expired after 27 days of hospitalization during which a prostatic abscess was drained and bilateral orchiectomy was done. Disseminated tuberculosis was diagnosed at autopsy. There had been no evidence of active pulmonary tuberculosis during this patient’s hospitalization, including negative acid-fast bacilli stains on bronchial washings done 5 days before his death. A total of 128 HCWs were exposed to this patient during this hospitalization. Of 95 exposed HCWs who previously had nonreactive tuberculin skin tests, 12 (13%) had newly positive tuberculin skin tests. The majority of conversions occurred among nurses, particularly those nurses who packed or irrigated the surgical wounds. Of note, all three autopsy personnel converted. In contrast, only 2 of 17 respiratory therapists exposed to this patient had conversion of their tuberculin skin test, suggesting that the transmission of tuberculosis from this patient did not come from the respiratory tract. The third report is by Rice et al, entitled “An Evaluation of Hospital Special-Ventilation-Room Pressures,” and assesses the magnitude and consistency of positive and negative airflow in hospital special-ventilation rooms.4 A total of 18 rooms were sampled, including 10 standard rooms (with no special ventilation), 4 airborne isolation rooms (with negative pressure), and 4 protective-environment rooms (with positive pressure). The results of this study showed that the pressure stability of these rooms varied by room and over time. Of the 274 pressure readings for airborne isolation rooms, 186 (68%) of the readings showed compliance with the Centers for Disease Control and Prevention recommendations. At times, the positive pressure in protective-environment rooms dropped suddenly and dramatically; one such episode was due to a loose fan belt. The inconsistency of the ventilation control of the specialventilation-room pressures noted in this study suggests that these rooms would not have been reliably capable of achieving their stated purpose.

Tuberculosis control in New York City hospitals

To assess the implementation of tuberculosis (TB) control measures in New York City hospitals in 1992 and determine trends during the subsequent 2 years. The 22 acute care facilities with the largest number of hospitalized TB patients in 1991 were selected for inclusion in the study. Medical and laboratory records of the 10 most recent acid fast bacilli (AFB) smear-positive patients in each of the selected facilities in 1992, 1993, and 1994 were reviewed by using a standardized questionnaire to determine risk factors for TB, previous history of TB, clinical signs and symptoms, AFB laboratory turnaround times, emergency department contact, timing of isolation, timing of treatment, case reporting, and status on discharge. The patients' rooms were evaluated for TB environmental control measures if the patient was still on respiratory isolation precautions. More than one third of patients were admitted with a previous history of TB, 31% were admitted with a cavitary lesion on chest x-ray examination, and 48% were known to have HIV infection. Eighty-five percent were admitted from the emergency department where they stayed for up to 116 hours (mean stay: 17 hours). The proportion of patients placed in AFB isolation on admission to the floor increased from 75% in 1992 to 84% in 1994. The proportion of patients given a minimum of four anti-TB drugs increased from 88% in 1992 to 94% in 1994. Patients "on isolation" were sharing rooms with up to nine other patients in 1992, whereas no patients were sharing rooms in the 1994 survey. In 1992, 51% of the rooms were under negative air flow with respect to the corridor. During the 1994 survey, 80% of rooms were under negative air flow. Between 1992 and 1994, the proportion of AFB isolation rooms with dust/mist respirators increased from 28% to 76% (p < 0.00001). Approximately 25% of discharged patients left against medical advice (no trend over time). The proportion of medically discharged patients with three negative AFB smears before discharge increased from 26% to 48% (p = 0.03) and the proportion referred for directly observed therapy increased from 15% to 53% (p = 0.00001). TB control efforts in New York City hospitals improved dramatically between 1992 and 1994. The ultimate control of TB will continue to depend on the coordinated efforts within and between health care facilities, providers, and the community.

Pseudo-outbreak of tuberculosis in an acute-care general hospital: epidemiology and clinical implications.

A 10-fold increase in patients with Mycobacterium tuberculosis-positive specimens in one hospital laboratory prompted an investigation. Clinical and epidemiological data, along with M tuberculosis DNA fingerprinting results, indicated that laboratory contamination led to nine false-positive M tuberculosis cultures. Pseudo-infection should be considered in patients with unusual tuberculosis presentations, negative acid-fast bacilli smears, and only one positive culture with a low colony count.

Pseudo-Outbreak of Tuberculosis in an Acute-Care General Hospital: Epidemiology and Clinical Implications

A 10-fold increase in patients with Mycobacterium tuberculosis-positive specimens in one hospital laboratory prompted an investigation. Clinical and epidemiological data, along with M tuberculosis DNA fingerprinting results, indicated that laboratory contamination led to nine false-positive M tuberculosis cultures. Pseudo-infection should be considered in patients with unusual tuberculosis presentations, negative acid-fast bacilli smears, and only one positive culture with a low colony count.

Impact of short-course therapy on tuberculosis drug resistance in South-West Burkina Faso

Setting: The Regional Tuberculosis Centre and the Muraz Centre in Bobo-Dioulasso, Burkina Faso. Objectives: To observe the trend of primary drug resistance in pulmonary tuberculosis patients 5 years into a short-course treatment programme and to assess the possible implementation of a further programme. Design: Bacteriological study of stains isolated from all newly diagnosed tuberculosis patients ( n = 300), all relapse cases ( n = 20) and all failure cases ( n = 58) from the Houet province, during the period from April 1992 to April 1994. Human immunodeficiency virus (HIV) serostatus was determined for the first 119 patients included in the study. Results:Mycobacterium tuberculosis was the predominant species as shown by 75.1% of the isolates; next was M. africanum, then atypical mycobacteria and finally M. bovis, representing 18.4%, 6.5% and 0.4% of the isolates respectively. Primary resistance (excluding atypical strains) was as follows: isoniazid 7.6%, ethambutol 1.0%, rifampicin 2.5%, and streptomycin 12.4%; 33.6% of the patients tested for HIV were HIV positive. There was no relationship between HIV serostatus and the identity of strains or drug resistance. However, negative acid-fast bacilli smear microscopy with positive culture was significantly more frequent in HIV-positive patients than in HIV-negative patients. Conclusion: This study shows a drop in primary resistance compared with previous studies carried out in Bobo-Dioulasso under the same conditions (setting, materials and methods, sampling procedures) in 1982 and 1986. This is consistent with the hypothesis that treatment monitoring and the introduction of short-course therapy in 1989 (2 HERZ/4 HR or 2 HRSZ/4 HR) have contributed to lower rates of primary drug resistance.

Screening Respiratory Specimens for Mycobacteria Culture

We performed this retrospective study to establish a new screening procedure for assessing the quality of respiratory specimens for mycobacteria cultures. For 1 year, we evaluated 299 samples for specimen quality by using a Gram’s stain method. Corresponding mycobacteria culture results were then compared with their Gram’s stain evaluation to determine a correlation between acceptable sputum specimens and positive results from mycobacteria culture. Study results indicated that screening sputum specimens before processing for mycobacteria culture eliminates specimens that are likely to yield negative acid-fast bacilli culture results.