Laryngeal swabs for diagnosing tuberculosis

Accuracy of upper respiratory tract samples to diagnose Mycobacterium tuberculosis: a systematic review and meta-analysis

BACKGROUND

Pulmonary tuberculosis due to Mycobacterium tuberculosis can be challenging to diagnose when sputum samples cannot be obtained, which is especially problematic in children and older people. We systematically appraised the performance characteristics and diagnostic accuracy of upper respiratory tract sampling for diagnosing active pulmonary tuberculosis.

METHODS

In this systematic review and meta-analysis, we searched MEDLINE, Cinahl, Web of Science, Global Health, and Global Health Archive databases for studies published between database inception and Dec 6, 2022 that reported on the accuracy of upper respiratory tract sampling for tuberculosis diagnosis compared with microbiological testing of sputum or gastric aspirate reference standard. We included studies that evaluated the accuracy of upper respiratory tract sampling (laryngeal swabs, nasopharyngeal aspirate, oral swabs, saliva, mouth wash, nasal swabs, plaque samples, and nasopharyngeal swabs) to be tested for microbiological diagnosis of tuberculous (by culture and nucleic acid amplification tests) compared with a reference standard using either sputum or gastric lavage for a microbiological test. We included cohort, case-control, cross-sectional, and randomised controlled studies that recruited participants from any community or clinical setting. We excluded post-mortem studies. We used a random-effects meta-analysis with a bivariate hierarchical model to estimate pooled sensitivity, specificity, and diagnostics odds ratio (DOR; odds of a positive test with disease relative to without), stratified by sampling method. We assessed bias using QUADAS-2 criteria. This study is registered with PROSPERO (CRD42021262392).

FINDINGS

We screened 10 159 titles for inclusion, reviewed 274 full texts, and included 71, comprising 119 test comparisons published between May 13, 1933, and Dec 19, 2022, in the systematic review (53 in the meta-analysis). For laryngeal swabs, pooled sensitivity was 57·8% (95% CI 50·5-65·0), specificity was 93·8% (88·4-96·8), and DOR was 20·7 (11·1-38·8). Nasopharyngeal aspirate sensitivity was 65·2% (52·0-76·4), specificity was 97·9% (96·0-99·0), and DOR was 91·0 (37·8-218·8). Oral swabs sensitivity was 56·7% (44·3-68·2), specificity was 91·3% (CI 81·0-96·3), and DOR was 13·8 (5·6-34·0). Substantial heterogeneity in diagnostic accuracy was found, probably due to differences in reference and index standards.

INTERPRETATION

Upper respiratory tract sampling holds promise to expand access to tuberculosis diagnosis. Exploring historical methods using modern microbiological techniques might further increase options for alternative sample types. Prospective studies are needed to optimise accuracy and utility of sampling methods in clinical practice.

FUNDING

UK Medical Research Council, Wellcome, and UK Foreign, Commonwealth and Development Office.

Diagnosis of laryngeal tuberculosis in a high TB burden area

PURPOSE

The larynx is the second most commonly affected site in the head and neck region in patients with extrapulmonary tuberculosis (TB). Despite this, the prevalence of laryngeal TB is largely unknown, particularly in areas with a high TB burden. The laboratory diagnosis of TB includes microscopy, culture and molecular testing. The aims of this study were to determine the prevalence of laryngeal TB in patients presenting with laryngeal pathology in a region with a high TB burden and to determine the optimal diagnostic methods for the diagnosis of laryngeal TB.

METHODS

This was a prospective descriptive study of 80 adult patients undergoing direct laryngoscopy and biopsy for laryngeal pathology in the Department of Otorhinolaryngology, Universitas Academic Hospital, Bloemfontein, South Africa over a 1 year period. Histopathological and microbiological investigations (microscopy, Xpert MTB/RIF, and TB culture) were performed on all laryngeal biopsies.

RESULTS

Five (6.25%) out of 80 patients were diagnosed with laryngeal TB. In one patient, the Xpert MTB/RIF assay was positive on the laryngeal tissue and histology showed granulomas. Two patients had granulomas on histology although the microbiological tests on the tissue were negative. Two patients had only positive tissue cultures for Mycobacterium tuberculosis. None of the biopsies had positive Ziehl-Neelsen stains.

CONCLUSION

The results suggest that the diagnosis of laryngeal TB required a combination of histopathology, culture and PCR and that the Xpert MTB/RIF assay is not a sensitive test for the diagnosis of laryngeal TB.

Laryngeal cytology: A cytological, histological, P16 and human papillomavirus study

BACKGROUND

Invasive diagnostic methods, such as punch biopsies, have a potential to produce undesirable side effects in the larynx, such as scarring and vocal dysfunction. This study is an attempt to assess the diagnostic potential of cytology to efficiently diagnose premalignant and malignant laryngeal lesions, while sparing patients the risk of complications of punch biopsies.

METHODS

Laryngeal smears, using endocervical-type brushes, and punch biopsies were procured from each patient. Smears were prepared and the brush was cut and put in Surepath preservative solution for cytological analysis and human papillomavirus (HPV) DNA testing. A Real-TM Quant kit that detects 14 HPV types was used for genotyping. Immunohistochemical staining for p16 was performed on cytological and histological specimens.

RESULTS

Cytological diagnosis was correct in 84.6%, 100% and 100% of cases with a histological diagnosis of squamous cell carcinomas, high-grade squamous intraepithelial lesions and benign lesions, respectively. However, cytological interpretation was correct only in 25% of low-grade squamous intraepithelial lesions. HPV DNA test was positive in only one case, which was a laryngeal polyp. Testing for p16 was negative in all the cytological and histological material.

CONCLUSION

Laryngeal cytology is a useful diagnostic tool in establishing the diagnosis of high-grade squamous epithelial cell abnormalities. Recognition of low-grade lesions, however, is challenging. HPV genotyping and p16 staining do not seem to be helpful ancillary techniques in cytological material procured from the larynx.

Upper Respiratory Tract Tuberculosis

Upper respiratory tract involvement in cases of tuberculosis (TB) of the head and neck continues to be described in the most recent reports from several different regions, including some from developed countries. Laryngeal TB is the most common of all forms of upper respiratory tract TB (URT-TB). Pulmonary lesions in URT-TB are present in about 20% of adults and about 50 to 60% of children. Systemic manifestations are uncommon. URT-TB is especially seen in patients with a variety of risk factors, such as the presence of human immunodeficiency virus (HIV) infection, diabetes, smoking, alcoholism, drug abuse, malignancies, and use of immunosuppressive drugs. Nodules or ulcerative lesions are seen on morphological examination. Endoscopic examination is required for mucosal lesions. Diagnosis of TB is suspected on an epidemiological basis in high-prevalence countries or from the failure of a patient to respond to routine treatment. Smear and/or histopathological examinations help in establishing the final etiological diagnosis. Treatment includes standard anti-TB chemotherapy for at least 6 months with four primary drugs during the initial intensive phase of 2 months and two or three primary drugs during the remaining maintenance phase of 4 months. Treatment is modified on the basis of culture and sensitivity reports in cases of suspected drug resistance. Surgical intervention may be required for some patients with abscess formation and progressive disease unresponsive to medical therapy. Airway obstruction, although rare, even in fulminant cases may require tracheostomy for relief.

Rapid culture-based diagnosis of pulmonary tuberculosis in developed and developing countries

Culturing Mycobacterium tuberculosis remains the gold standard for the laboratory diagnosis of pulmonary tuberculosis, with 9 million new cases and 1.5 million deaths mainly in developing countries. Reviewing data reported over 20 years yields a state-of-the-art procedure for the routine culture of M. tuberculosis in both developed and developing countries. Useful specimens include sputum, induced sputum, and stools collected in quaternary ammonium preservative-containing sterile cans. The usefulness of other non-invasive specimens remains to be evaluated. Specimens can be collected in a diagnosis kit also containing sampling materials, instructions, laboratory requests, and informed consent. Automated direct LED fluorescence microscopy after auramine staining precedes inoculation of an egg-lecithin-containing culture solid medium under microaerophilic atmosphere, inverted microscope reading or scanning video-imaging detection of colonies and colonies identification by recent molecular methods. This procedure should result in a diagnosis of pulmonary tuberculosis as fast as 5 days. It may be implemented in both developed and developing countries with automated steps replaceable by manual steps depending on local resources.

Nasopharyngeal aspiration for diagnosis of pulmonary tuberculosis

BACKGROUND

Confirmation of pulmonary tuberculosis (PTB) in young children is difficult as they seldom expectorate sputum.

AIM

To compare sputa obtained by nasopharyngeal aspiration and by sputum induction for staining and culture of Mycobacterium tuberculosis.

PATIENTS AND METHODS

Patients from Mulago Hospital, Kampala with symptoms suggestive of PTB were considered for inclusion in the study. Those with a positive tuberculin test and/or a chest radiograph compatible with tuberculosis were recruited. Infection with human immunodeficiency virus (HIV) was confirmed by duplicate enzyme-labelled immunosorbent assay or in children <15 months by polymerase chain reaction (PCR). Direct PCR was undertaken on 82 nasopharyngeal aspirates.

RESULTS

Of 438 patients referred, 94 were recruited over a period of 5 months. Median (range) age was 48 (4-144) months. Of 63 patients tested, 69.8% were infected with HIV. Paired and uncontaminated culture results were available for 88 patients and smear results for 94 patients. Nasopharyngeal aspirates were smear-positive in 8.5% and culture-positive in 23.9%. Induced sputa were smear-positive in 9.6% and culture positive in 21.6%. Overall, 10.6% were smear-positive, 25.5% were culture-positive and 26.6% had smear and/or culture confirmed tuberculosis. Direct PCR on nasopharyngeal aspirates had a sensitivity of 62% and specificity of 98% for confirmation of culture-positive tuberculosis.

CONCLUSIONS

Nasopharyngeal aspiration is a useful, safe and low-technology method for confirmation of PTB and, like sputum induction, can be undertaken in outpatient clinics.

Childhood tuberculosis in Malawi: caseload, diagnostic practices and treatment outcomes

There were 22,982 cases of TB registered in Malawi in 1998, of which 2739 (11.9%) were children. Children accounted for 11.3% of all case notifications with smear-positive pulmonary TB (PTB), 21.3% with smear-negative PTB and 15.9% with extrapulmonary TB (EPTB). A significantly higher proportion of TB cases were diagnosed in central hospitals. Only 45% of children completed treatment. There were high rates of death (17%), default (13%) and unknown treatment outcomes (21%). Treatment outcomes were worse in younger children and in children with smear-negative PTB. In 2001, all 44 non-private hospitals in Malawi that register and treat children with tuberculosis (TB) were surveyed to determine actual diagnostic practice. This cross sectional study identified 150 children aged 14 years or below in hospital receiving anti-TB treatment, 98 with pulmonary TB (PTB) and 52 with extrapulmonary TB (EPTB). Median duration of illness was 8 weeks. Most patients had fever, no response to anti-malarial treatment and antibiotics, and 40% had a positive family history of TB. Nearly 45% had weight for age < 60%. Diagnosis was mainly based on clinical features and radiography, with less than 10% having tuberculin skin tests or HIV serology, and very few having other sophisticated investigations. Diagnostic difficulties make it difficult to accurately define the actual burden of childhood TB in Malawi. Diagnostic practices are poor and treatment outcomes unsatisfactory.

Childhood tuberculosis: out of control?

Because of the difficulty of confirming the diagnosis of childhood tuberculosis and because children do not make a significant contribution to the spread of tuberculosis, the burden of childhood tuberculosis in the world is uncertain. Several estimates make use of an arbitrary calculation assigning 10% of the tuberculosis burden to children. Available data linking the incidence of tuberculosis to the proportion of the tuberculosis caseload represented by children suggest an exponential rise in the proportion of the tuberculosis caseload caused by children as the tuberculosis incidence rises so that children may constitute nearly 40% of the caseload in certain high incidence communities. This review discusses the global burden of childhood tuberculosis and attempts to quantify this, the role of HIV/AIDS and tuberculosis in children, the problems this creates for diagnosis, and the occurrence of drug resistant tuberculosis in children. In the developing world, childhood tuberculosis is not under control, and, despite its importance as a child health problem, remains a neglected orphan disease.

Tuberculous osteomyelitis of the mandible: a case report

Osteomyelitis of jaws caused by infection with Mycobacterium tuberculosis is uncommon, especially in children. We present a case of tuberculous osteomyelitis in a young child. Its clinical presentation, with features similar to a dento-alveolar abscess, underline the importance of considering it in the differential diagnosis of jaw lesions. We discuss of the diagnostic techniques, management and preventive measures, and stress the importance of history taking during clinical examination.