Use of real time polymerase chain reaction for detection of M. tuberculosis, M. avium and M. kansasii from clinical specimens

Prevalence of Mycobacterium kansasii in clinical and environmental isolates, a systematic review and meta-analysis

Background

Mycobacterium kansasii infection is one of the most common causes of non-tuberculosis mycobacterial (NTM) disease worldwide. However, accurate information on the global prevalence of this bacterium is lacking. Therefore, this study was conducted to investigate the prevalence of M. kansasii in clinical and environmental isolates.

Methods

Databases, including PubMed, Scopus, and the Web of Science, were utilized to gather articles on the prevalence of M. kansasii in clinical and environmental isolates. The collected data were analyzed using Comprehensive Meta-Analysis software.

Results

A total of 118 and 16 studies met the inclusion criteria and were used to analyze the prevalence of M. kansasii in clinical and environmental isolates, respectively. The prevalence of M. kansasii in NTM and environmental isolates were 9.4 and 5.8%, respectively. Subsequent analysis showed an increasing prevalence of M. kansasii over the years. Additionally, the results indicated a significant difference in the prevalence of this bacteria among different regions.

Conclusion

The relatively high prevalence of M. kansasii among NTM isolates suggests the need for further implementation of infection control strategies. It is also important to establish appropriate diagnostic criteria and management guidelines for screening this microorganism in environmental samples in order to prevent its spread, given its high prevalence in environmental isolates.

Prevalence of Non-Tuberculosis Mycobacterium Pulmonary Disease in HIV-1 Patients with Presumptive Pulmonary Tuberculosis in Western Kenya

Background

Non-tuberculous mycobacteria (NTMs) are ubiquitous, free-living, environmental saprophytic microorganisms. NTMs belong to the genus Mycobacterium which includes Mycobacterium tuberculosis (MTB). NTMs have lately been a major cause of pulmonary disease (PD) in immuno-compromised individuals including HIV-1 patients. NTMs and MTB appear similar based on microscopy, radiology, and clinical symptoms; consequently, this may lead to misdiagnosis. This study sought to establish the prevalence of NTM pulmonary disease in HIV-1 patients presumed to have pulmonary tuberculosis.

Methods

A cross-sectional analytical laboratory study design was used targeting 617 adult HIV-1 infected patients presenting with presumptive pulmonary TB at Bungoma County Hospital Comprehensive Care Clinic in Western Kenya between July 2021 to June 2022.

Results

A total of 75 (12.2%, 4.6 -9.8 CI) of the participants presented with presumptive MTB and had TB-like symptoms while 542 (87.8%, 12.5 -30.7 CI) were negative. Additionally, 56 (9.1%) were infected with NTMs. HIV-positive participants had a significantly higher prevalence of NTMs 62 (11.8%, 5.6 -9.2 CI) compared to 2 (2.1%, 0.4 -1.8 CI). In HIV + study participants P<0.0001. M. avium was the most prevalent NTM, 25(33.3%), followed by M. fortuitum 20 (26.7%). A significant number of the isolates were M. tuberculosis 10 (13.3%) as well as M. kansasii 8 (10.7%).

Conclusion

There seems to be a high prevalence of NTMPD in HIV-1 patients which is assumed to be pulmonary TB. Differential diagnosis of the mycobacterium species is necessary to help improve disease management and outcomes in this group of patients.

Molecular detection of Mycobacterium tuberculosis in pulmonary and extrapulmonary samples in a hospital-based study

OBJECTIVE

Tuberculosis (TB), caused by Mycobacterium tuberculosis (Mtb), remains a deadly infectious disease. India contributes to one-third of the global TB burden. However, no studies have been carried out in the Telangana (Hyderabad) population using real-time polymerase chain reaction (RT-PCR). Therefore, the current study evaluated the role of RT-PCR as a rapid and non-invasive test to diagnose TB by testing for pulmonary tuberculosis (PTB) and extrapulmonary tuberculosis (EPTB).

MATERIALS AND METHODS

This hospital-based study examined 1670 samples (900 EPTB; 770 PTB) comprising tissue (n = 537), peritoneal fluid (n = 420), sputum (n = 166), bronchial fluid (n = 126), cerebrospinal fluid (n = 145), ascetic fluid (n = 76), sputum pus (n = 78), urine (n = 79), and bronchoalveolar fluid (n = 43) samples. DNA from samples was separated using specific isolation kits and subjected to RT-PCR.

RESULTS

In this study, we enrolled 1670 subjects and categorized 54.4% as females and 45.6% as males. The collected samples were categorized as 48.5% of fluid samples, followed by tissue (32.2%), sputum (9.9%), urine (4.7%), and pus-swab (4.6%). RT-PCR analysis revealed that 4.7% patients were positive for Mtb. Our results revealed that 61% of the affected patients were male and 39% were female. Among the specimen types, tissue samples gave the highest proportion of positive results (36.3%).

CONCLUSION

The results showed that RT-PCR should be implemented and given top priority in TB diagnosis to save time and facilitate a definitive diagnosis. Tissue samples are highly recommended to screen the Mtb through the technique RTPCR. Future studies should extend the technique to the global population and exome sequencing analysis should be performed to identify TB risk markers.

Diagnostic performance of real time PCR and MALDI-TOF in the detection of nontuberculous mycobacteria from clinical isolates

This study aimed to evaluate the performance of real-time PCR (qPCR) and MALDI-TOF for accurate and timely detection of nontuberculous mycobacterium (NTM) from clinical isolates. We collected fifty NTM suspected Mycobacteria Growth Indicator Tube (MGIT) cultures and analysed the diagnostic performance of qPCR and VITEK MS using Line Probe Assay (LPA) GenoType CM (Common Mycobacteria) as gold standard. The qPCR assays targeting 16S rRNA, ITS and IS6110 genes were developed for the identification of NTM and Mycobacterium tuberculosis complex (MTBC). LPA GenoType CM, a PCR technique targeting 23S rRNA gene, followed by reverse hybridization and line probe technology identified 90% of Mycobacterium species including M. fortuitum (16%,n = 8), M. intracellulare (10%,n = 5), M. gordonae (10%,n = 5), M. xenopi (4%,n = 2), M. scrofulaceum (4%,n = 2), Mycobacterium additional species (AS) (32%,n = 16) and MTBC (14%,n = 7), qPCR detected 80% of Mycobacterium species (NTM, 66% (n = 33) and MTBC, 14% (n = 7)) and MALDI-TOF, 52% (M. fortuitum (12%,n = 6), M. intracellulare (10%, n = 5), M. simiae (8%,n = 4), M. gordonae (8%,n = 4), and MTBC (14%,n = 7)). Sensitivity of qPCR and MALDI-TOF was 88.9% and 57.8%, respectively with 100% specificity. The combination of qPCR and MALDI-TOF remains an appropriate test for timely diagnosis of Mycobacterium species. This may eventually assist to detect the cases that may have been missed by phenotypic tests and enhance the NTM diagnosis capability to improve effective patient management.

Surgical treatment for chronic cervical lymphadenitis in children. Experience from a tertiary care paediatric centre on non-tuberculous mycobacterial infections

OBJECTIVES

Non-tuberculous mycobacteria are the most frequent cause of chronic lymphadenitis in children. We reviewed treatment and outcomes of paediatric patients with chronic cervical lymphadenitis, to better understand their differential diagnosis, surgical indication, complication and recover.

METHODS

A retrospective study was carried out on children who underwent surgery from 2013 to 2016 at Meyer Children's University Hospital, Florence, Italy. Time to cure, type of surgery, and complications rate were determined and etiologic agents were identified and correlated to their clinical presentation.

RESULTS

275 children were evaluated. Nearly 98% of the patients were cured regardless of which therapeutic option was used and surgery was necessary in 38.2% of children. Complete excisional biopsy ensured recover in 97.7% of patients compared with the non-excisional surgical group 88.2% (p = 0.06). Re-interventions were needed in the 2.3% of complete excision group and in two cases of the incision and drainage group; all of them developed fistula and were caused by Mycobacterium avium complex. Excision followed by adjunctive antibiotic therapy was favoured in the majority of the patients (80.1%, n = 71).

CONCLUSION

In cases of non-tuberculous mycobacteria lymphadenitis, surgery is the treatment of choice and it is closely related to a favourable prognosis.

Non-tuberculous Mycobacteria isolated from Pulmonary samples in sub-Saharan Africa - A Systematic Review and Meta Analyses

Pulmonary non-tuberculous mycobacterial (NTM) disease epidemiology in sub-Saharan Africa is not as well described as for pulmonary tuberculosis. Earlier reviews of global NTM epidemiology only included subject-level data from one sub-Saharan Africa country. We systematically reviewed the literature and searched PubMed, Embase, Popline, OVID and Africa Wide Information for articles on prevalence and clinical relevance of NTM detection in pulmonary samples in sub-Saharan Africa. We applied the American Thoracic Society/Infectious Disease Society of America criteria to differentiate between colonisation and disease. Only 37 articles from 373 citations met our inclusion criteria. The prevalence of pulmonary NTM colonization was 7.5% (95% CI: 7.2%–7.8%), and 75.0% (2325 of 3096) occurred in males, 16.5% (512 of 3096) in those previously treated for tuberculosis and Mycobacterium avium complex predominated (27.7% [95% CI: 27.2–28.9%]). In seven eligible studies, 27.9% (266 of 952) of participants had pulmonary NTM disease and M. kansasii with a prevalence of 69.2% [95% CI: 63.2–74.7%] was the most common cause of pulmonary NTM disease. NTM species were unidentifiable in 29.2% [2,623 of 8,980] of isolates. In conclusion, pulmonary NTM disease is a neglected and emerging public health disease and enhanced surveillance is required.

Mycobacterium kansasii

The incidence of Mycobacterium kansasii varies widely over time and by region, but this organism remains one of the most clinically relevant isolated species of nontuberculous mycobacteria. In contrast to other common nontuberculous mycobacteria, M. kansasii is infrequently isolated from natural water sources or soil. The major reservoir appears to be tap water. Infection is likely acquired through the aerosol route, with low infectivity in regions of endemicity. Human-to-human transmission is thought not to occur. Clinical syndromes and radiological findings of M. kansasii infection are mostly indistinguishable from that of Mycobacterium tuberculosis, thus requiring microbiological confirmation. Disseminated disease is uncommon in HIV-negative patients and usually associated with severe immunosuppression. The majority of patients with M. kansasii pulmonary disease have underlying pulmonary comorbidities, such as smoking, chronic obstructive pulmonary disease, bronchiectasis, and prior or concurrent M. tuberculosis infection. Surveys in Great Britain, however, noted higher rates, with 8 to 9% of M. kansasii infections presenting with extrapulmonary disease. Common sites of extrapulmonary disease include the lymph nodes, skin, and musculoskeletal and genitourinary systems. The specificity of gamma interferon release assays (IGRAs) for M. tuberculosis may be reduced by M. kansasii infection, as M. kansasii encodes CFP-10 and ESAT-6, two antigens targeted by IGRAs. A study conducted to evaluate the therapy in rifampin-resistant disease found that patients with acquired rifampin resistance were treated with daily high-dose ethambutol, isoniazid, sulfamethoxazole, and pyridoxine combined with aminoglycoside therapy. Given the potential toxicities, particularly with aminoglycoside therapy, clarithromycin and/or moxifloxacin therapy could be considered as alternatives.

Validation of a Multiplex Real-Time PCR Assay for Detection of Mycobacterium spp., Mycobacterium tuberculosis Complex, and Mycobacterium avium Complex Directly from Clinical Samples by Use of the BD Max Open System

A multiplex real-time PCR was validated on the BD Max open system to detect different Mycobacterium tuberculosis complex, Mycobacterium avium complex, and Mycobacterium spp. directly from clinical samples. The PCR results were compared to those with traditional cultures. The multiplex PCR assay was found to be a specific and sensitive method for the rapid detection of mycobacteria directly from clinical specimens.

Non-tuberculous mycobacterial head and neck infections in children: Analysis of results and complications for various treatment modalities

OBJECTIVES

Analyze the results and complications of various surgical interventions in a large cohort of children with non-tuberculous mycobacterial (NTM) head and neck infections and suggest a heuristic treatment protocol for managing this condition while aiming to maximize cure and minimize complications.

METHODS

Retrospective chart review of 104 consecutive patients diagnosed with head and neck NTM at a tertiary paediatric hospital between January 1994 and December 2013 inclusive.

RESULTS

104 patients ranged in age between 8 months to 15 years (mean age 27 months) were reviewed and 97 patients were included in the final analysis. 6 patients excluded due to lack of follow-up and one excluded due to systemic immunocompromised condition. Sub-sites of NTM infections were submandibular (n=48, 46%), cervical (n=40, 38%), parotid (n=18, 17%) and submental (n=4, 4%). Some patients had more than one lesion so counted twice. Higher cure rates were demonstrated for primary excision (81%, p<0.01) versus incisional interventions (44%, p<0.01). Marginal mandibular nerve palsy following surgery was seen in 7 patients (7.2%). This was permanent in 4 patients (4%) and temporary in 3 patients (3%). All children who were complicated with marginal mandibular palsies had lesions in the submandibular region. The rate of palsy for submandibular disease alone was 15%, while 8% presented permanent palsy and 6% temporary. Marginal mandibular nerve palsy was more likely following excisional compared to incisional procedures (6 versus 1 patient, p<0.01). Hypertrophic scarring occurred in 7 patients: 3 patients following excision and 4 patients after an incisional procedure. One patient suffered long term spinal accessory nerve damage presented as winged scapula.

CONCLUSIONS

Excision of NTM provides better cure rates compared to incision although at the expense of long term post-surgical morbidity. Excision should probably be the first line of treatment when the risk for neural damage is low. Incision and drainage with or without antimycobacterial treatment may be the preferred option for at-risk sub-sites (submandibular or parotid) in order to reduce long term morbidity.