Recovery of Non-tuberculous Mycobacteria from Water is Influenced by Phenotypic Characteristics and Decontamination Methods

Fernandes, Henry Marcel Zalona; Conceição, Emilyn Costa; Gomes, Karen Machado; Silva, Marley G da; Dias, Rubens C. S.; Duarte, Rafael Silva

doi:10.1007/s00284-019-01704-w

Cited by 12 publications

(17 citation statements)

References 46 publications

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“…In this study, the Xpert system did not show false positive results among NTM isolates, mainly due to the increase in prevalence of disease-associated NTM, as has already been described by other authors 15 - 17 . Therefore, NTM should be suspected in conditions where smear microscopy tests yield positive results and are undetected by the Xpert assay 18 .…”

Section: Discussionsupporting

confidence: 85%

Cost analysis of smear microscopy and the Xpert assay for tuberculosis diagnosis: average turnaround time

Figueredo

Miranda

Santos

et al. 2020

Rev. Soc. Bras. Med. Trop.

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Introduction: Rapid and accurate tuberculosis detection is critical for improving patient diagnosis and decreasing tuberculosis transmission. Molecular assays can significantly increase laboratory costs; therefore, the average time and economic impact should be evaluated before implementing a new technology. The aim of this study was to evaluate the cost and average turnaround time of smear microscopy and Xpert assay at a university hospital. Methods: The turnaround time and cost of the laboratory diagnosis of tuberculosis were calculated based on the mean cost and activity based costing (ABC). Results: The average turnaround time for smear microscopy was 16.6 hours while that for Xpert was 24.1 hours. The Xpert had a mean cost of USD 17.37 with an ABC of USD 10.86, while smear microscopy had a mean cost of USD 13.31 with an ABC of USD 6.01. The sensitivity of smear microscopy was 42.9% and its specificity was 99.1%, while the Xpert assay had a sensitivity of 100% and a specificity of 96.7%. Conclusions: The Xpert assay has high accuracy; however, the turnaround time and cost of smear microscopy were lower than those of Xpert.

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Section: Discussionsupporting

confidence: 85%

Cost analysis of smear microscopy and the Xpert assay for tuberculosis diagnosis: average turnaround time

Figueredo

Miranda

Santos

et al. 2020

Rev. Soc. Bras. Med. Trop.

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“…The presence of contamination by non-mycobacteria and the length of time required for NTM growth means there is a higher risk of NTM going undetected using typical environmental NTM testing methods. Current decontamination processes and selective media, such as 7H11, have also been shown to suppress the growth of some species of NTM [10,19]. Both clinical and environmental samples processed for NTM often require methods or media with high selectivity to restrict the growth of contaminants that are often present in the sample [16].…”

Section: Discussionmentioning

confidence: 99%

“…Due to the diverse bacterial communities that exist in environmental samples, methods used for clinical samples are not commonly used for environmental samples [8]. Decontamination agents such as sodium hydroxide (NaOH), oxalic acid, and cetylpyridinium chloride (CPC) have all successfully been used to treat environmental samples for the recovery of NTM [9], however their use and concentration are variable among laboratory protocols and can result in differential isolation of species [10]. Elimination of non-mycobacterial species in a sample allows for the detection of NTM present in a previously overgrown sample.…”

Section: Introductionmentioning

confidence: 99%

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Evaluation of a new culture medium for isolation of nontuberculous mycobacteria from environmental water samples

Alexander¹,

Furlong²,

Baron³

et al. 2021

PLoS ONE

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Nontuberculous mycobacteria (NTM) are waterborne pathogens commonly found in building water systems where they are a primary concern to vulnerable patient populations and can cause severe disease. The recovery of NTM from environmental samples can be a laborious undertaking and current pre-treatment methods and selective media lack sensitivity. We explored the use of the highly selective Rapidly Growing Mycobacteria (RGM) medium for culturing NTM from environmental water samples compared to existing methods. In total, 223 environmental water samples, including potable and non-potable water, were cultured for NTM using three culture media. In addition to direct culture on RGM medium, each sample was cultured on Middlebrook 7H10 medium and Mitchison 7H11 medium after pre-treatment with 0.2M KCl-HCl. Additionally, 33 distinct species of NTM were inoculated onto RGM medium and 7H10 medium in parallel to directly compare their growth. The use of RGM medium alone without pre-treatment provided a sensitivity (91%) comparable to that offered by culture on both 7H10 and 7H11 with acid pretreatment (combined sensitivity; 86%) with significantly less overgrowth and interference from other organisms on RGM medium. The average concentration of NTM observed on RGM medium alone was comparable to or greater than the NTM concentration on either medium alone or combined. Thirty-three species were examined in parallel and all tested strains of 27 of these species successfully grew on RGM medium, including 19 of 21 from the CDC’s healthcare-associated infections species list. RGM medium was successful at recovering environmental NTM without a pre-treatment, greatly reducing labor and materials required to process samples. Simplification of culture processing for environmental NTM will allow for a better assessment of their presence in building water systems and the potential for reduced exposure of susceptible populations.

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“…Their presence in tap water is attributed to their natural resistance to commonly used water disinfectants. [ 2 ] Because of this, routine exposure to NTM, most notably in the form of airborne particles, is extremely common. Considering the rarity of clinically significant NTM infection, it is safe to assume that certain risk factors are important for an individual to get an NTM infection.…”

Section: Introductionmentioning

confidence: 99%

Nontuberculous mycobacteria: A report of eighteen cases from a tertiary care center in India

et al. 2020

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Context: Nontuberculous mycobacteria (NTM) are ubiquitous mycobacteria present in environment and generally affect patients with either structural lung disease or immunosuppression and commonly involve lungs, lymph node, or skin. Materials and Methods: Between July 2016 and February 2019, 18 cases of NTM were diagnosed and their relevant clinical, diagnostic, and treatment details were recorded after taking informed consent. Results: We report 18 cases of NTM involving lungs ( n = 11), skin and soft tissue ( n = 3), joint ( n = 2), genitourinary ( n = 1), and central nervous system ( n = 1). History of immunosuppression was present in two patients, whereas history of some form of intervention was seen in six patients. Mycobacterium fortuitum group ( n = 5) was the most commonly isolated organism, followed by Mycobacterium avium complex ( n = 4), Mycobacterium abscessus ( n = 3), Mycobacterium kansasii ( n = 2), and Mycobacterium chelonae ( n = 1). In two patients, M. chelonae and M. abscessus were isolated in succession. Of these 18 patients, clinical response was present in 15 of the patients. Diagnosis and treatment of NTM in resource limited settings is extremely challenging. Conclusion: Most of the patients with NTM are misdiagnosed and are treated as tuberculosis in India, sometimes with a multidrug resistance regimen, which results in significant morbidity and mortality. We present these cases to shed some light on the epidemiology of NTM in this part of India.

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Recovery of Non-tuberculous Mycobacteria from Water is Influenced by Phenotypic Characteristics and Decontamination Methods

Cited by 12 publications

References 46 publications

Cost analysis of smear microscopy and the Xpert assay for tuberculosis diagnosis: average turnaround time

Cost analysis of smear microscopy and the Xpert assay for tuberculosis diagnosis: average turnaround time

Evaluation of a new culture medium for isolation of nontuberculous mycobacteria from environmental water samples

Nontuberculous mycobacteria: A report of eighteen cases from a tertiary care center in India

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