Occurrence of Nontuberculous Mycobacterial Pulmonary Infection in an Endemic Area of Tuberculosis

The majority of investigations of the epidemiology of nontuberculous mycobacteria (NTM) have focused on highly developed nations with a low prevalence of tuberculosis. In contrast, the Para state of north Brazil represents an area of high tuberculosis prevalence and increasing NTM incidence. Toward the goal of understanding the dynamics of infection by all Mycobacterium species, we report patient characteristics and the identification of NTM strains isolated from sputum samples from patients that were residents of Para, a state in the Amazon region, Northern of Brazil, over the period January 2010 through December 2011 (2 years). The 29 NTM patients comprised 13.5% of positive mycobacterial cultures over the 2-year period. A major risk factor for NTM pulmonary disease was previous tuberculosis (76%). Further, the average age of NTM patients (52 years) was significantly higher than that of tuberculosis patients (39 years) and more were female (72.4% vs. 37.4%). Unlike other Brazilian states, NTM pulmonary patients in Para were infected with a different spectrum of mycobacteria; primarily the rapidly growing Mycobacterium massiliense and Mycobacterium simiae complex.     

Cooccurrence of Free-Living Amoebae and Nontuberculous Mycobacteria in Hospital Water Networks,and Preferential Growth of Mycobacterium avium in Acanthamoeba lenticulata

The incidence of lung and other diseases due to nontuberculous mycobacteria (NTM) is increasing. NTM sources include potable water, especially in households where NTM populate pipes, taps, and showerheads. NTM share habitats with free-living amoebae (FLA) and can grow in FLA as parasites or as endosymbionts. FLA containing NTM may form cysts that protect mycobacteria from disinfectants and antibiotics. We first assessed the presence of FLA and NTM in water and biofilm samples collected from a hospital, confirming the high prevalence of NTM and FLA in potable water systems, particularly in biofilms. Acanthamoeba spp. (genotype T4) were mainly recovered (8/17), followed by Hartmannella vermiformis (7/17) as well as one isolate closely related to the genus Flamella and one isolate only distantly related to previously described species. Concerning mycobacteria, Mycobacterium gordonae was the most frequently found isolate (9/17), followed by Mycobacterium peregrinum (4/17), Mycobacterium chelonae (2/17), Mycobacterium mucogenicum (1/17), and Mycobacterium avium (1/17). The propensity of Mycobacterium avium hospital isolate H87 and M. avium collection strain 104 to survive and replicate within various FLA was also evaluated, demonstrating survival of both strains in all amoebal species tested but high replication rates only in Acanthamoeba lenticulata. As A. lenticulata was frequently recovered from environmental samples, including drinking water samples, these results could have important consequences for the ecology of M. avium in drinking water networks and the epidemiology of disease due to this species.     

Nontuberculous mycobacteria in respiratory samples from patients with pulmonary tuberculosis in the state of Rond?nia, Brazil

The main cause of pulmonary tuberculosis (TB) is infection with Mycobacterium tuberculosis (MTB). We aimed to evaluate the contribution of nontuberculous mycobacteria (NTM) to pulmonary disease in patients from the state of Rondônia using respiratory samples and epidemiological data from TB cases. Mycobacterium isolates were identified using a combination of conventional tests, polymerase chain reaction-based restriction enzyme analysis of hsp65 gene and hsp65 gene sequencing. Among the 1,812 cases suspected of having pulmonary TB, 444 yielded bacterial cultures, including 369 cases positive for MTB and 75 cases positive for NTM. Within the latter group, 14 species were identified as Mycobacterium abscessus, Mycobacterium avium, Mycobacterium fortuitum, Mycobacterium intracellulare, Mycobacterium gilvum, Mycobacterium gordonae, Mycobacterium asiaticum, Mycobacterium tusciae, Mycobacterium porcinum, Mycobacterium novocastrense, Mycobacterium simiae, Mycobacterium szulgai, Mycobacterium phlei and Mycobacterium holsaticum and 13 isolates could not be identified at the species level. The majority of NTM cases were observed in Porto Velho and the relative frequency of NTM compared with MTB was highest in Ji-Paraná. In approximately half of the TB subjects with NTM, a second sample containing NTM was obtained, confirming this as the disease-causing agent. The most frequently observed NTM species were M. abscessus and M. avium and because the former species is resistant to many antibiotics and displays unsatisfactory cure rates, the implementation of rapid identification of mycobacterium species is of considerable importance.     

Distribution of non-tuberculosis mycobacteria strains from suspected tuberculosis patients by heat shock protein 65 PCR–RFLP

The genus Mycobacterium contains more than 150 species. Non-tuberculosis mycobacteria (NTM) often cause extrapulmonary and pulmonary disease. Mycobacteria detection at species level is necessary and provides useful information on epidemiology and facilitates successful treatment of patients. This retrospective study aimed to determine the incidence of the NTM isolates and Mycobacterium tuberculosis (Mtb) in clinical specimens collected from Iranian patients during February 2011–December 2013, by PCR–restriction fragment length polymorphism analysis (PRA) of the hsp65 gene. We applied conventional biochemical test and hsp65–PRA identification assay to identify species of mycobacteria in specimens from patients suspected of having mycobacterial isolates. This method was a sensitive, specific and effective assay for detecting mycobacterial species and had a 100% sensitivity and specificity for Mtb and Mycobacterium avium complex (MAC) species. Using PRA for 380 mycobacterial selected isolates, including 317 Mtb, four Mycobacterium bovis and of the 59 clinical isolates, the most commonly identified organism was Mycobacterium kansasii (35.6%), followed by Mycobacterium simiae (16.9%), Mycobacterium gordonae (16.9%), Mycobacterium fortuitum (5.1%), Mycobacterium intracellulare (5.1%), Mycobacterium avium (5.1%), Mycobacterium scrofulaceum (3.4%), Mycobacterium gastri (3.4%), Mycobacterium flavescens (3.4%), Mycobacterium chelonae (3.4%) and Mycobacterium nonchromogenicum (1.7%). PRA method, in comparison with classical methods, is rapid, useful and sensitive for the phylogenetic analysis and species detection of mycobacterial strains. Mycobacterium kansasii is the most common cause of infection by NTM in patients with non-HIV and HIV which demonstrated a high outbreak and diversity of NTM strains in our laboratory.     

Synthesis and biological activity of new salicylanilide N,N-disubstituted carbamates and thiocarbamates

The development of novel antimicrobial drugs represents a cutting edge research topic. In this study, 20 salicylanilide N,N-disubstituted carbamates and thiocarbamates were designed, synthesised and characterised by IR, ¹H NMR and ¹³C NMR. The compounds were evaluated in vitro as potential antimicrobial agents against Mycobacterium tuberculosis and nontuberculous mycobacteria (Mycobacterium avium and Mycobacterium kansasii) as well as against eight bacterial and fungal strains. Additionally, we investigated the inhibitory effect of these compounds on mycobacterial isocitrate lyase and cellular toxicity. The minimum inhibitory concentrations (MICs) against mycobacteria were from 4 μM for thiocarbamates and from 16 μM for carbamates. Gram-positive bacteria, including methicillin-resistant Staphylococcus aureus, were inhibited with MICs from 0.49 μM by thiocarbamates, whilst Gram-negative bacteria and most of the fungi did not display any significant susceptibility. All (thio)carbamates mildly inhibited isocitrate lyase (up to 22%) at a concentration of 10 μM. The (thio)carbamoylation of the parent salicylanilides led to considerably decreased cytotoxicity and thus improved the selectivity indices (up to 175). These values indicate that some derivatives are attractive candidates for future research.     

Nontuberculous Mycobacterial Ocular Infections—Comparing the Clinical and Microbiological Characteristics between Mycobacterium abscessus and Mycobacterium massiliense

Purpose

To analyze the clinical characteristics of nontuberculous mycobacterial (NTM) ocular infections and the species-specific in vitro antimicrobial susceptibility.

Material and Methods

In 2000 to 2011 at the National Taiwan University Hospital, multilocus sequencing of rpoB, hsp65 and secA was used to identify NTM isolates from ocular infections. The clinical presentation and treatment outcomes were retrospectively compared between species. Broth microdilution method was used to determine the minimum inhibitory concentrations of amikacin (AMK), clarithromycin (CLA), ciprofloxacin (CPF), levofloxacin (LVF), moxifloxacin (MXF) and gatifloxacin (GAF) against all strains. The activities of antimicrobial combinations were assessed by the checkerboard titration method.

Results

A total of 24 NTM strains (13 Mycobacterium abscessus and 11 Mycobacterium massiliense) were isolated from 13 keratitis, 10 buckle infections, and 1 canaliculitis cases. Clinically, manifestations and outcomes caused by these two species were similar and surgical intervention was necessary for medically unresponsive NTM infection. Microbiologically, 100% of M. abscessus and 90.9% of M. massiliense ocular isolates were susceptible to amikacin but all were resistant to fluoroquinolones. Inducible clarithromycin resistance existed in 69.3% of M. abscessus but not in M. massiliense isolates. None of the AMK-CLA, AMK-MXF, AMK-GAF, CLA-MXF and CLA-GAF combinations showed synergistic or antagonistic effect against both species in vitro.

Conclusions

M. abscessus and M. massiliense are the most commonly identified species for NTM ocular infections in Taiwan. Both species were resistant to fluoroquinolones, susceptible to amikacin, and differ in clarithromycin resistance. Combined antimicrobial treatments showed no interaction in vitro but could be considered in combination with surgical interventions for eradication of this devastating ocular infection.     

Levels of anti-cytokine antibodies may be elevated in patients with pulmonary disease associated with non-tuberculous mycobacteria

Pulmonary disease due to non-tuberculous mycobacteria (NTM) is caused by several species (particularly Mycobacterium avium, Mycobacterium intracellulare) that are abundant in the environment. Th1 cytokines such as interferon (IFN)-γ are important in the control of mycobacteria, but in vitro production of IFN-γ is not deficient in adult patients with pulmonary NTM disease. Antibodies reactive with IFN-γ have been described in patients with disseminated NTM disease, but it is not clear whether they are common in pulmonary disease. Here we show that patients with pulmonary NTM have a higher level of anti-IFN-γ and anti-GM-CSF antibodies than healthy controls, although some controls also have high levels. Levels of anti-IFN-γ antibodies did not correlate with levels of total immunoglobulin. Longitudinal studies are required to determine whether anti-cytokine autoantibodies are consequence rather than a cause of pulmonary NTM disease.     

Spatio-temporal study of environmental nontuberculous mycobacteria isolated from Wardha district in Central India

During the last two decades, nontuberculous mycobacteria (NTM) have gained in importance but there is still a paucity of data, particularly for environmental isolates. We studied, over a period of two years, the spatio-temporal features of NTM isolates obtained from different environmental sources in Wardha district, India. A total of 1398 samples (699 each of soil and water) were tested and 170 (12.2%) yielded NTM isolates, including 123 from soil and 47 from water samples. Out of 170 NTM isolates, 107 (63%) belonged to potentially pathogenic mycobacteria (PPM) and 63 (37%) to the less pathogenic mycobacterial (LPM) group. Overall, maximum isolation was obtained in rainy season (20.3%) followed by winter (13.5%), post rainy (8.7%) and summer seasons (5.8%). Mycobacterium fortuitum, Mycobacterium gordonae and Mycobacterium avium complex (MAC) were common isolates followed by Mycobacterium flavescens, Mycobacterium scrofulaceum, Mycobacterium simiae and Mycobacterium marinum. From soil, isolation of NTM was highest from grounds used for community gatherings (42.8%) followed by soil from residential premises (27.7%) and near the wells (26.0%). From drinking water sources, highest NTM isolation was obtained from wells (15.4%) followed by treated water tanks (6.9%), household receptacles (6.3%), hand pumps (5.6%) and tap water supply (3.5%). Isolation from natural canal water was 6.6%, while from drainage and waste water ponds isolation was 8.3%. The results of the study revealed that in Wardha district, NTM are present both in the soil and drinking water. As NTM can be pathogenic, particularly in immune-compromised individuals, these can be of potential risk to the human population.     

Membrane-active antimicrobial peptides and human placental lysosomal extracts are highly active against mycobacteria

Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis, manifests discreet strategies to subvert host immune responses, which enable the pathogen to survive and multiply inside the macrophages. This problem is further worsened by the emergence of multidrug resistant mycobacterial strains, which make most of the anti-tuberculous drugs ineffective. It is thus imperative to search for and design better therapeutic strategies, including employment of new antibiotics. Recently, naturally produced antimicrobial molecules such as enzymes, peptides and their synthetic analogs have emerged as compounds with potentially significant therapeutical applications. Although, many antimicrobial peptides have been identified only very few of them have been tested against mycobacteria. A major limitation in using peptides as therapeutics is their sensitivity to enzymatic degradation or inactivity under certain physiological conditions such as relatively high salt concentration. Here, we show that NK-2, a peptide representing the cationic core region of the lymphocytic effector protein NK-lysin, and Ci-MAM-A24, a synthetic salt-tolerant peptide derived from immune cells of Ciona intestinalis, efficiently kill Mycobacterium smegmatis and Mycobacterium bovis-BCG. In addition, NK-2 and Ci-MAM-A24 showed a synergistic killing effect against M. smegmatis, no cytotoxic effect on mouse macrophages at bactericidal concentrations, and were even found to kill mycobacteria residing inside the macrophages. We also show that human placental lysosomal contents exert potent killing effect against mycobacteria under acidic and reducing growth conditions. Electron microscopic studies demonstrate that the lysosomal extract disintegrate bacterial cell membrane resulting in killing of mycobacteria.     

Non‐Tuberculosis mycobacterium speciation using HPLC under Revised National TB Control Programme (RNTCP) in India

Aims

Non‐Tuberculous Mycobacteria (NTM) are ubiquitous in nature. The data on prevalence of NTM under the RNTCP is scarce. Many NTM species have clinical significance, and hence their identification and speciation are important.

Methods and Results

It is a cross‐sectional study conducted at the five RNTCP accredited culture and drug susceptibility testing (CDST) laboratory. The culture isolates from AFB positive but Immunochromatographic test negative samples were taken for identification and speciation using HPLC. Of the total 266 isolates only 164 isolates had a second sample received at the laboratory. The speciation was done using HPLC for those isolates. The type of species identified are: 26·8% (44) were Mycobacterium chelonae, 12·8% (21) were Mycobacterium fortuitum, 9% (15) were Mycobacterium gordonae, 9% (15) were Mycobacterium tuberculosis complex, 6·1% (10) were Mycobacterium kansasii, 4·9% (8) were Mycobacterium simiae, 2·4% (4) were Mycobacterium thermophile, 1·2% (2) were Mycobacterium gastri, 0·6% (1) were Mycobacterium scrofulaceum, 0·6% (1) were Mycobacterium avium and 4·9% (8) isolates had chromatogram which was un‐interpretable.

Conclusion

Identification and its speciation of NTM are not routinely done under TB control programme. Since HPLC could identify 95% of isolates belonging to 10 species, the speciation of NTM using HPLC should gain importance in the diagnosis of disease caused by NTM.

Significance and Impact of Study

NTM are emerging as important causative agents of pulmonary and extra pulmonary disease, the ability to recognize disease caused by NTM and subsequently treat such disease has become increasingly important. The identification of NTM up to its species level should gain importance in all TB reference Laboratories.     

Mycobacteria mobility shift assay: a method for the rapid identification of Mycobacterium tuberculosis and nontuberculous mycobacteria

The identification of mycobacteria is essential because tuberculosis (TB) and mycobacteriosis are clinically indistinguishable and require different therapeutic regimens. The traditional phenotypic method is time consuming and may last up to 60 days. Indeed, rapid, affordable, specific and easy-to-perform identification methods are needed. We have previously described a polymerase chain reaction-based method called a mycobacteria mobility shift assay (MMSA) that was designed for Mycobacterium tuberculosis complex (MTC) and nontuberculous mycobacteria (NTM) species identification. The aim of this study was to assess the MMSA for the identification of MTC and NTM clinical isolates and to compare its performance with that of the PRA-hsp65 method. A total of 204 clinical isolates (102 NTM and 102 MTC) were identified by the MMSA and PRA-hsp65. For isolates for which these methods gave discordant results, definitive species identification was obtained by sequencing fragments of the 16S rRNA and hsp65 genes. Both methods correctly identified all MTC isolates. Among the NTM isolates, the MMSA alone assigned 94 (92.2%) to a complex or species, whereas the PRA-hsp65 method assigned 100% to a species. A 91.5% agreement was observed for the 94 NTM isolates identified by both methods. The MMSA provided correct identification for 96.8% of the NTM isolates compared with 94.7% for PRA-hsp65. The MMSA is a suitable auxiliary method for routine use for the rapid identification of mycobacteria.     

Delivery of Aerosolized Liposomal Amikacin as a Novel Approach for the Treatment of Nontuberculous Mycobacteria in an Experimental Model of Pulmonary Infection

Pulmonary infections caused by nontuberculous mycobacteria (NTM) are an increasing problem in individuals with chronic lung conditions and current therapies are lacking. We investigated the activity of liposomal amikacin for inhalation (LAI) against NTM in vitro as well as in a murine model of respiratory infection. Macrophage monolayers were infected with three strains of Mycobacterium avium, two strains of Mycobacterium abscessus, and exposed to LAI or free amikacin for 4 days before enumerating bacterial survival. Respiratory infection was established in mice by intranasal inoculation with M. avium and allowing three weeks for the infection to progress. Three different regimens of inhaled LAI were compared to inhaled saline and parenterally administered free amikacin over a 28 day period. Bacteria recovered from the mice were analyzed for acquired resistance to amikacin. In vitro, liposomal amikacin for inhalation was more effective than free amikacin in eliminating both intracellular M. avium and M. abscessus. In vivo, inhaled LAI demonstrated similar effectiveness to a ∼25% higher total dose of parenterally administered amikacin at reducing M. avium in the lungs when compared to inhaled saline. Additionally, there was no acquired resistance to amikacin observed after the treatment regimen. The data suggest that LAI has the potential to be an effective therapy against NTM respiratory infections in humans.     

Gut bacterium of Dendrobaena veneta (Annelida: Oligochaeta) possesses antimycobacterial activity

The new bacterial strain with antimycobacterial activity has been isolated from the midgut of Dendrobaena veneta (Annelida). Biochemical and molecular characterization of isolates from 18 individuals identified all as Raoultella ornithinolytica genus with 99% similarity. The bacterium is a possible symbiont of the earthworm D. veneta. The isolated microorganism has shown the activity against four strains of fast-growing mycobacteria: Mycobacterium butiricum, Mycobacterium jucho, Mycobacterium smegmatis and Mycobacterium phlei. The multiplication of the gut bacterium on plates with Sauton medium containing mycobacteria has caused a lytic effect. After the incubation of the cell free extract prepared from the gut bacterium with four strains of mycobacteria in liquid Sauton medium, the cells of all tested strains were deformed and divided to small oval forms and sometimes created long filaments. The effect was observed by the use of light, transmission and scanning microscopy. Viability of all examined species of mycobacteria was significantly decreased. The antimycobacterial effect was probably the result of the antibiotic action produced by the gut bacterium of the earthworm. The application of ultrafiltration procedure allowed to demonstrate that antimicrobial substance with strong antimycobacterial activity from bacterial culture supernatant, is a protein with the molecular mass above 100 kDa.     

Discovery of benzothiazole amides as potent antimycobacterial agents

From a high throughput screening of commercially available libraries against nontuberculous mycobacteria and Mycobacterium tuberculosis, numerous hits were identified with moderate activity. Extensive medicinal chemistry optimization has led to a series of potent benzothiazole amide antimycobacterial agents. Replacement of the adamantyl group with cyclohexyl derivatives and further development of this series resulted in an advanced lead compound, CRS400393, which demonstrated excellent potency and a mycobacteria-specific spectrum of activity. MIC values ranged from 0.03 to 0.12?μg/mL against Mycobacterium abscessus and other rapid-grower NTM, and 1–2?μg/mL against Mycobacterium avium complex. The preliminary mechanism of action studies suggested these agents may target MmpL3, a mycobacterial mycolic acid transporter. The series has demonstrated in vivo efficacy in a proof of concept mouse model of M. abscessus infection.     

Complete Genome Sequence of Mycobacterium fortuitum subsp. fortuitum Type Strain DSM46621

Mycobacterium fortuitum is a member of the rapidly growing nontuberculous mycobacteria (NTM). It is ubiquitous in water and soil habitats, including hospital environments. M. fortuitum is increasingly recognized as an opportunistic nosocomial pathogen causing disseminated infection. Here we report the genome sequence of M. fortuitum subsp. fortuitum type strain DSM46621.     

Development of multiplex PCR assays based on the 16S-23S rRNA internal transcribed spacer for the detection of clinically relevant nontuberculous mycobacteria

Aims: To accelerate the identification and differentiation of clinically relevant nontuberculous mycobacteria (NTM) with two sets of multiplex PCR (mPCR) targeting the 16S–23S rRNA internal transcribed spacer (ITS) region for timely patient management. Methods and Results: Two mPCR assays were developed: Slow‐Growers (SG) mPCR was used for the detection of slow‐growing mycobacteria, which included Mycobacterium avium complex, Mycobacterium kansasii, Mycobacterium gordonae and Mycobacterium xenopi whilst the other mPCR assay labelled as Fast‐Growers (FG) mPCR was used for the detection of Mycobacterium fortuitum complex, Mycobacterium abscessus and Mycobacterium chelonae. In these assays, a common forward primer based on a conserved section of the 16S rRNA region was used in conjunction with species‐specific reverse primers. The mPCRs were tested against 247 clinical mycobacterial isolates and demonstrated 100% specificity and sensitivity. Identification of the mycobacterial species was also validated by DNA sequencing of the 16S–23S ITS region and when further confirmation was needed, hsp65 sequencing was performed. Conclusions: The mPCR assays could be a potentially useful diagnostic tool for the rapid and accurate identification of clinically relevant NTM. Significance and Impact of the Study: In this study, we looked at the frequency of hospital isolated NTM over the last 5 years (2005–2010), and an mPCR targeting the ITS region was developed for NTM species that appeared to be more prevalent in the context of Singapore.     

HMGN2 regulates non‐tuberculous mycobacteria survival via modulation of M1 macrophage polarization

Non‐tuberculous mycobacteria (NTM), also known as an environmental and atypical mycobacteria, can cause the chronic pulmonary infectious diseases. Macrophages have been suggested as the main host cell to initiate the innate immune responses to NTM infection. However, the molecular mechanism to regulate the antimicrobial immune responses to NTM is still largely unknown. Current study showed that the NTM clinical groups, Mycobacterium abscessus and Mycobacterium smegmatis, significantly induced the M1 macrophage polarization with the characteristic production of nitric oxide (NO) and marker gene expression of iNOS, IFNγ, TNF‐α, IL1‐β and IL‐6. Interestingly, a non‐histone nuclear protein, HMGN2 (high‐mobility group N2), was found to be spontaneously induced during NTM‐activated M1 macrophage polarization. Functional studies revealed that HMGN2 deficiency in NTM‐infected macrophage promotes the expression of M1 markers and the production of NO via the enhanced activation of NF‐κB and MAPK signalling. Further studies exhibited that HMGN2 knock‐down also enhanced IFNγ‐induced M1 macrophage polarization. Finally, we observed that silencing HMGN2 affected the survival of NTM in macrophage, which might largely relevant to enhanced macrophage polarization into M1 phenotype under the NTM infection. Collectively, current studies thus suggested a novel function of HMGN2 in regulating the anti‐non‐tuberculous mycobacteria innate immunity of macrophage.     

Increase in Nontuberculous Mycobacteria Isolated in Shanghai,China: Results from a Population-Based Study

Background

In China, the prevalence of nontuberculous mycobacteria (NTM) in isolates from mycobacterial culture-positive patients with pulmonary tuberculosis (TB) is largely unknown.

Methods

We used conventional biochemical and 16S rRNA gene sequencing to identify species of mycobacteria in specimens from patients suspected of having TB. Drug-susceptibility testing was performed on NTM isolates using the proportion method. We also determined the independent risk factors associated with infection with NTM compared with infection with Mycobacterium tuberculosis.

Results

The overall rate of NTM isolated from mycobacterial culture-positive patients was 5.9% in this population, with a significantly increasing trend from 3.0% in 2008 to 8.5% in 2012 (P for trend <0.001). The organism most frequently identified was M. kansasii (45.0%), followed by M. intracellulare (20.8%) and M. chelonae/abscessus (14.9%). The overall proportion of isolates resistant to the four first-line anti-TB agents were 64.6% for isoniazid, 77.6% for streptomycin, 63.3% for rifampicin and 75.1% for ethambutol. The risk factors most often associated with NTM infection were older age (P for trend <0.001), being a resident of Shanghai (adjusted odds ratio [aOR], 1.48; 95% CI, 1.10–2.00), having been treated for tuberculosis (aOR, 1.64; 95% CI, 1.18–2.29), having a cavity on chest X-ray (aOR, 1.51; 95% CI, 1.16–1.96), and being sputum smear–negative (aOR, 1.59; 95% CI, 1.16–2.18).

Conclusions

The prevalence of NTM isolated in Shanghai increased between 2008 and 2012, thus clinicians should consider NTM as a possible cause of TB-like disease. Accurate species identification is imperative so that proper treatment can be administered for diseases caused by the diversity of NTM species.     

Comparison of Culture Methods for Isolation of Nontuberculous Mycobacteria from Surface Waters

The environment is the likely source of most nontuberculous mycobacteria (NTM) involved in human infections, especially pulmonary, skin, and soft tissue infections. In order to measure the prevalence of NTM in different aquatic ecosystems, we tried to standardize the culture methods used for surface water testing since many procedures have been described previously. Cultivation of mycobacteria requires long-term incubation in rich media and inactivation of rapidly growing microorganisms whose growth impedes observation of mycobacterial colonies. Consequently, the two criteria used for evaluation of the methods examined were (i) the rate of inhibition of nontarget microorganisms and (ii) the efficiency of recovery of mycobacteria. We compared the competitive growth of Mycobacterium chelonae and M. avium with nontarget microorganisms on rich Middlebrook 7H11-mycobactin medium after treatment by several chemical decontamination methods that included acids, bases, detergent, or cetylpyridinium chloride (CPC) with and without an antibiotic cocktail, either PANTA (40 U/ml polymyxin, 4 μg/ml amphotericin B, 16 μg/ml nalidixic acid, 4 μg/ml trimethoprim, and 4 μg/ml azlocillin) or PANTAV (PANTA plus 10 μg/ml vancomycin). Our results showed that treatment for 30 min with CPC (final concentration, 0.05%) of water concentrated by centrifugation, followed by culture on a rich medium supplemented with PANTA, significantly decreased the growth of nontarget microorganisms (the concentrations were 6.2 ± 0.4 log₁₀ CFU/liter on Middlebrook 7H11j medium and 4.2 ± 0.2 log₁₀ CFU/liter on Middlebrook 7H11j medium containing PANTA [P < 0.001]), while the effect of this procedure on NTM was not as great (the concentrations of M. chelonae on the two media were 7.0 ± 0.0 log₁₀ CFU/liter and 6.9 ± 0.0 log₁₀ CFU/liter, respectively, and the concentrations of M. avium were 9.1 ± 0.0 log₁₀ CFU/liter and 8.9 ± 0.0 log₁₀ CFU/liter, respectively). We propose that this standardized culture procedure could be used for detection of NTM in aquatic samples.It is generally accepted that environmental exposure, particularly exposure through water, is the main source of most human infections caused by nontuberculous mycobacteria (NTM). The incidence of waterborne NTM skin and soft tissue infections in immunocompetent patients is increasing (31), as is the incidence of pulmonary infections that occur due to aerosol inhalation (15, 31). Ingestion or inhalation of contaminated water (while swimming, for instance) could also be a source of NTM infections in children (31). Because NTM are emerging pathogens for humans and domestic animals, it is important to identify their environmental sources and reservoirs and to measure their proliferation and persistence in freshwater ecosystems. A robust and standardized method for environmental detection of NTM is necessary to do this.NTM are ubiquitous and can be isolated from a variety of aquatic ecosystems, including natural water, wastewater, drinking water, recreational water, and industrial water (16, 51). Even hospital water has been reported to be contaminated by NTM (31). More precisely, aquatic plants, amoebae, and aquatic vertebrates and invertebrates could be considered NTM reservoirs in aquatic ecosystems in natural environments and in drinking water distribution systems or buildings and homes (19, 26, 37). Once present in a system, mycobacteria may proliferate and persist (4).Typically, the methods usually used for detection of NTM are methods that are used for clinical microbiology and have not been adapted for environmental samples. Surface water samples are quite different from clinical samples, since they may contain low levels of NTM but typically contain highly diverse bacterial communities in which the concentrations of bacteria range from 10⁴ to 10⁷ cells per ml (54). This microbial diversity makes it likely that nontarget species will overgrow NTM in nutrient-rich medium. Several studies have been conducted to determine the optimum decontamination method for inhibiting the growth of nontarget bacteria in NTM assays, although most of the methods were developed for clinical samples (2, 8, 20, 42, 56). Moreover, no clear consensus for treatment of environmental samples has emerged from these studies. The combination of chemical decontamination and addition of antibiotics to culture medium has not been studied previously for water surface samples.The aim of this study was to develop and validate an improved method for detecting and counting NTM in surface water. To do this, we compared the results for recovery of mycobacteria from water samples and inactivation of nontarget microorganisms (fungi and bacteria other than mycobacteria) when various antibiotics and chemical decontaminants were used.     

Identification of antimicrobial activity among new sulfonamide metal complexes for combating rapidly growing mycobacteria

Mycobacteriosis is a type of infection caused by rapidly growing mycobacteria (RGM), which can vary from localized illness, such as skin disease, to disseminated disease. Amikacin, cefoxitin, ciprofloxacin, clarithromycin, doxycycline, imipenem and sulfamethoxazole are antimicrobial drugs chosen to treat such illnesses; however, not all patients obtain the cure. The reason why the treatment does not work for those patients is related to the fact that some clinical strains present resistance to the existing antimicrobial drugs; thereby, the research of new therapeutic approaches is extremely relevant. The coordination of antimicrobial drugs to metals is a promising alternative in the development of effective compounds against resistant microorganisms. Sulfonamides complexed with Au, Cd, Ag, Cu, and Hg have shown excellent activity against a variety of microorganisms. Considering the importance of fighting against infections associated with RGM, the objective of this study is to evaluate the antimycobacterial activity of metal complexes of sulfonamides against RGM. Complexed sulfonamides activity were individually tested and in association with trimethoprim. The minimum inhibitory concentration (MIC) and time-kill curve of compounds against the standard strains of RGM [Mycobacterium abscessus (ATCC 19977), Mycobacterium fortuitum (ATCC 6841) and Mycobacterium massiliense (ATCC 48898)] was determined. The interaction of sulfonamides with trimethoprim was defined by inhibitory concentration index fractional for each association. The results showed that sulfonamides complexed whit metals have outstanding antimicrobial activity when compared to free sulfamethoxazole, bactericidal activity and synergistic effect when combined with trimethoprim.