Nested PCR for diagnosis of tuberculous lymphadenitis and PCR-SSCP for identification of rifampicin resistance in fine-needle aspirates

Cytomorphological patterns and clinical features of presumptive tubercular lymphadenitis patients and their comparison with bacteriological detection methods: a cross-sectional study

INTRODUCTION

Tuberculous lymphadenitis (TBLN) is an infection of the lymph node caused by Mycobacterium tuberculosis. Histological diagnoses of presumptive patients are often accompanied by cytomorphological features. However, the sensitivities of these features are often precluded by the variable degrees of narrative similarities compared to other diagnostic modalities.

OBJECTIVE

The aim of this study was to investigate and compare the cytomorphological and clinical features of presumptive TBLN patients with bacteriological detection methods.

METHODS

A similar cohort of TBLN patients from our previous study who were enrolled prospectively from the ALERT Specialized Hospital, Addis Ababa, Ethiopia, was considered for this analysis. SPSS version 26 was used for data analysis. Descriptive analysis was conducted to characterize the study population using the independent variable and presented with frequency tables. The chi-square test was used to measure the association. A P-value of < 0.05 was considered statistically significant.

RESULTS

Using FNAC, 60/126 (47.6%) of the participants were reported to have features consistent with TB. Of the total FNAC-positive cases, many (30/60 and 27/60) showed pattern B (caseous necrosis only) and pattern C (epithelioid granuloma with caseous necrosis), respectively. Strong concordance was observed in Pattern A (abundant caseous necrosis with few epithelioid macrophages) followed by patterns B and C with GeneXpert and MGIT culture (P value < 0.001). Night sweats and alcohol intake were shown to correlate with positive cases as reported by FNAC (P value = 0.008 respectively), GeneXpert (P value = 0.02 & 0.001), and culture methods (P-value = < 0.001 & 0.002).

CONCLUSION

Cytomorphological features, particularly patterns A, B, and C, could be considered in the diagnosis of TBLN given their comparable outcomes with bacteriological detection methods. On another note, we recommend that due care and attention be given when treating TBLN patients based solely on clinical presentation, as these diagnostics may be prone to false results, leading to inappropriate administration of anti-TB drugs and other consequences.

Diagnosis of tuberculous lymphadenitis using fine needle aspiration biopsy

BACKGROUND

Tuberculous lymphadenitis is the commonest form of extrapulmonary tuberculosis. However, the optimal approach to diagnosis, employing biopsy by either fine needle aspiration (FNA) or surgical excision, remains uncertain.

AIMS

To evaluate the diagnostic value of biopsy using each of the component diagnostic modalities of FNA (microscopy, cytology and culture), and compare these with excision biopsy in the diagnosis of tuberculous lymphadenitis in a predominantly migrant population in Melbourne.

METHODS

A retrospective examination of tuberculous lymphadenitis cases presenting to Western Health over 12 years was conducted. Using a reference method of positive culture of Mycobacterium tuberculosis, the diagnostic sensitivities of each modality employed in FNA were determined.

RESULTS

Forty-two subjects having FNA and 30 having excision biopsy as the initial investigation were compared. Among specimens obtained by FNA, sensitivity of microscopy was 18% (95% confidence interval (CI): 5–40%) and sensitivity of cytology was 38% (95% CI: 20–59%). For specimens obtained by excision biopsies, sensitivities for microscopy and histology were 17% (95% CI: 2–32%) and 96% (95% CI: 88–100%) respectively. Sensitivity of culture performed on FNA specimens was 86% (95% CI: 65–97%).

CONCLUSIONS

Given the relatively high sensitivity of mycobacterial cultures from FNA, this study supports its routine use as the initial investigation in most patients with suspected tuberculous lymphadenitis. Microscopy and cytology add relatively little to the clinical utility of FNA

Endobronchial ultrasound-guided transbronchial needle aspiration in diagnosing intrathoracic tuberculosis

BACKGROUND

Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) is a minimally invasive procedure that has enabled mediastinal and hilar lymph node assessment with a high sensitivity, but its role in the diagnosis of intrathoracic tuberculosis (TB) has not been established.

METHODS

We prospectively studied 59 patients suspected of having TB with thoracic lymph node lesions or intrapulmonary lesions accessible by EBUS-TBNA at a clinical center for thoracic medicine from January 2010 to December 2011. Bronchoscopic findings, EBUS-TBNA procedures, pathologic findings, and microbiologic results were recorded.

RESULTS

Of 59 eligible patients, 41 patients had TB, 5 had lung cancer, 7 had inflammation, and 6 had sarcoidosis. Sensitivity was 85%, specificity was 100%, positive and negative predictive values were 100% and 75%, respectively, and accuracy was 90% by EBUS-TBNA for TB. Pathologic findings were consistent with TB in 80% of patients (33 of 41), and in 27% (11 of 41) the smear was positive. A total of 37 patients with TB had cultures, of whom 17 (46%) were positive. There were 80 mediastinal and hilar lymph nodes and 5 intrapulmonary lesions that were biopsied in the 41 patients with TB. Multivariate logistic regression revealed that short-axis diameter was an independent risk factor associated with positive pathology, smear, and culture (p < 0.05). Additionally, pathology showing necrosis was an independent risk factor associated with a positive culture.

CONCLUSIONS

Endobronchial ultrasound-guided transbronchial needle aspiration has a high diagnostic yield in the investigation of suspected intrathoracic TB by means of aspiration of intrathoracic lymph nodes and tracheobronchial wall-adjacent lung lesions.

A systematic review of rapid drug susceptibility tests for multidrug-resistant tuberculosis using rifampin resistance as a surrogate

BACKGROUND

The emergence of multidrug-resistant tuberculosis (MDR-TB) has prompted the development of rapid drug susceptibility assays with a focus on rifampin in recent years. Systematic reviews with evaluation of predictive values for different assays are scarce.

METHOD

MEDLINE was searched on 6 September 2008 for English articles that contain concurrent original data for generating summary measures of sensitivity, specificity and likelihood ratios of rapid rifampin susceptibility assays.

RESULTS/CONCLUSIONS

Significant heterogeneity was found in likelihood ratios across studies of all assays except nitrate reductase assay and colorimetric assays. Although rapid assays are fairly reliable for ruling out MDR-TB, careful consideration of clinical risk factors is required before using these assays to rule in MDR-TB under different epidemiological settings.

Computed tomography guided fine needle aspiration cytology of mass lesions of lung: Our experience

CONTEXT

Computerized tomography (CT) guided fine needle aspiration cytology (FNAC) of lung lesions has rapidly emerged as a less-invasive, cheap, rapid and fairly accurate diagnostic aid in lung lesions.

AIMS

The purpose of this present study was to evaluate the effectiveness of CT-guided FNAC in the diagnosis of pulmonary mass lesions (both benign and malignant) and to determine the complication rate of this procedure.

SETTINGS AND DESIGN

We conducted an institution-based, prospective study on 127 patients who presented with pulmonary mass lesions.

MATERIALS AND METHODS

After proper consent was obtained, CT-guided transthoracic fine needle aspiration was done and their diagnoses were confirmed by appropriate methods. The results were analyzed statistically.

RESULTS

Out of 127 cases selected for the study, 59.8% were males while the rest were females. Cough was the most common symptom present in 71.2% cases, followed by weight loss (62.4%). 21.2% cases were cytologically benign. Adenocarcinoma (54.2%) was the commonest malignant tumor. FNAC provided at least 96% sensitivity and 100% specificity in diagnosing lung tumors. Among the benign lesions, specific diagnoses were obtained in 48.1% cases. Thus, altogether a specific diagnosis was obtained in 109 of 127 cases, i.e. 85.8%. No major complication was noted.

CONCLUSIONS

CT-guided FNAC is an extremely valuable and fairly accurate diagnostic aid of intrathoracic mass lesions, with a reasonable rate of complication.

Endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) of mediastinal lymph nodes: experience from region with high prevalence of tuberculosis

Utility of EUS-FNA in diagnosing granulomatous lesions of mediastinum in regions with high prevalence of tuberculosis has not yet been evaluated. In the present study, utility and limitations of EUS-FNA of mediastinal lesions from a tertiary care center with high prevalence of tuberculosis were studied. All cases where EUS-FNA had been performed to diagnose mediastinal lymphadenopathy from January 2006 to December 2008 were retrieved from the files of cytopathology laboratory. These were reviewed by the cytopathologist. Two hundred and eighty one EUS-FNA aspirates from 269 patients were evaluated. Satisfactory aspirates were available in 259 cases. A cytological diagnosis of granulomatous lymphadenitis was rendered in 206 cases. Of these, tuberculosis could be established as an etiology in 76 cases and sarcoidosis in 7 cases only. In remaining 123 cases the etiology of granulomatous lymphadenitis could not be established and clinical correlation was suggested. Malignancies were diagnosed or suspected in 24 and 5 cases, respectively. The study highlights that the dilemma of tuberculosis versus sarcoidosis persists in regions with high prevalence of tuberculosis. However, EUS-FNA is useful in diagnosing unsuspected malignancies and confirming the presence of granulomatous lymphadenitis.

Combining fine-needle aspiration biopsy (FNAB) and high-resolution melt analysis to reduce diagnostic delay in Mycobacterial lymphadenitis

Tuberculous lymphadenitis is the most common cause of extra-pulmonary tuberculosis (TB) in developing countries. Lymphadenitis caused by non-tuberculous mycobacteria (NTM) requires consideration, particularly in immunocompromised patients and children in developed countries. Fine-Needle Aspiration Biopsy (FNAB) offers a valuable specimen collection technique, but culture confirmation, mycobacterial speciation and drug resistance testing (if indicated) is often unavailable in TB endemic areas and result in unacceptable diagnostic delay. We evaluated the diagnostic value of high-resolution DNA melting (HRM) analysis in the diagnosis of mycobacterial lymphadenopathy using FNAB and an inexpensive transport medium. Specimens were collected from patients referred to the FNAB Clinic at Tygerberg Hospital (June 2007-May 2008) with clinical mycobacterial lymphadenitis. Cytology, culture, and HRM were performed on all specimens. The reference standard for disease was defined as positive cytology (morphological evidence plus mycobacterial visualization) and/or a positive culture. Specimens were collected from 104 patients and mycobacterial disease was confirmed in 54 (51.9%); 52 Mycobacterium tuberculosis, 1 Mycobacterium Bovis BCG and 1 NTM. Cytology was positive in 83.3% (45/54) and culture in 72.2% (39/54) of patients. HRM identified 57.4% (31/54) of cases. By using the defined reference standard, we recorded 94.0% specificity and 51.9% sensitivity (positive predictive value 90.3%) with HRM analysis.HRM analysis allowed rapid and species specific diagnosis of mycobacterial lymph adenitis in the majority of patients, permitting early institution of appropriate therapy. Optimization of this technique requires further study.

Applications of molecular techniques to fine-needle aspiration biopsy

The effectiveness of fine-needle aspiration biopsy (FNAB) for rendering a specific diagnosis can be improved by applying several ancillary modalities. This review details several applications of molecular techniques using FNAB specimens with an emphasis on those used for patient care. A detailed search of the literature was conducted to collect all reports that used FNAB for different types of molecular tests. Several types of molecular tests, including in-situ hybridization, polymerase chain reaction, Southern blotting, and gene microarrays using FNAB specimens have been reported. These tests have been used with different organ systems and different objectives, including the detection of cancer cells, diagnosis, distinction of benign and malignant disease, prediction of response to chemotherapy, risk assessment, and selection of patients for targeted therapy. Except for a few tests such as assessment of HER2/neu for gene amplification in breast cancer, detection of clonality in hematopoietic neoplasms, and specific chromosomal translocations in the former and in the diagnosis of soft tissue sarcoma, most of the molecular tests using FNAB specimens are currently investigational. The reported literature indicates the excellent potential of using material procured from FNAB for almost any type of molecular test. Whereas few of these tests alone are used for patient care, some of them have the potential for clinical use in the near future.

Assessment of possible tuberculous lymphadenopathy by PCR compared to non-molecular methods

Tuberculosis is a major public health problem in India and other developing countries and has formed a lethal partnership with AIDS. It often presents a diagnostic challenge especially when clinical presentation is suggestive but bacteriological proof is lacking. The objective of this study was to compare the various diagnostic techniques in clinically suspected cases of tubercular lymph nodes and to find a suitable, cost-effective but sensitive and specific method for diagnosis. A total of 100 cases were recruited for the study. Fine needle aspiration cytology was done in all cases and the smears prepared were processed for Giemsa, Ziehl-Neelsen's, Kinyoun and Papanicolaou stains. Parts of the aspirated materials were assessed by fluorescent staining, culture and PCR. Seventy-four percent of aspirates were positive by fluorescent stain while only 22% were positive by culture. PCR could be performed in 55 cases, out of which 22 (40%) were positive. When compared to culture, the sensitivity and specificity of PCR were found to be 89.5% and 86.1%, respectively. Fluorescent stain was found to be the most sensitive (81.8%) of the conventional methods but showed poor specificity (28.2%). Interestingly, PCR detected 80% of smear-negative but culture-positive cases.

Molecular genetic methods for diagnosis and antibiotic resistance detection of mycobacteria from clinical specimens

Mycobacteria comprise a diverse group of bacteria that are widespread in nature, some of which cause significant disease in humans. Members of the Mycobacterium tuberculosis complex (MTBC) are the most important human pathogens of the genus Mycobacterium. Traditional methods for detection and identification of mycobacteria include microscopy, culture and phenotypic tests. These methods either lack sensitivity, specificity, or are time consuming. Advances in the field of molecular biology have provided rapid diagnostic tools that have reduced the turnaround times for detecting MTBC and drug resistance in cultures and directly in clinical specimens from weeks to days. This review discusses the molecular genetic techniques for detecting and identifying MTBC as well as drug resistance of mycobacteria in clinical specimens.

Diagnosis of tuberculous lymphadenitis in Butajira, rural Ethiopia

Tuberculous lymphadenitis (TBLN) is a diagnostic challenge in sub-Saharan Africa, where there is a high rate of human immunodeficiency virus (HIV) infection. This study aimed to find ways to improve the diagnosis in Butajira, rural Ethiopia, where TBLN constitutes 40% of the total tuberculosis (TB) diagnosis. Among 147 clinically suspected cases, 107 (72.8%) were confirmed as TBLN by fine-needle aspiration (FNA) cytology and acid-fast bacillus (AFB) smear examination. Of the remaining 40 cases, denoted non-tuberculous lymphadenitis (NTBLN) after this smear examination, 37 (92.5%) showed a cytological pattern with neutrophil aggregates. The clinical manifestations were similar and cervical lymph nodes were the most affected in these 2 groups. 24 of the 107 TBLN cases (22.4%) and 9 (22.5%) of the other cases were seropositive for HIV infection (p > 0.5). FNA cytology combined with AFB smear examination is a good alternative to histology in rural Ethiopia where the expertise in taking biopsies is very limited. Polymerase chain reaction for Mycobacterium tuberculosis complex DNA was positive in 15 of 23 cases tested with NTBLN cytology, showing that an additional independent criterion for the presence of M. tuberculosis is needed for diagnosis in lymphadenitis cases of this kind. These findings could help to strengthen the diagnostic algorithm suggested by the National TB Control Program.