Diversity,Community Composition,and Dynamics of Nonpigmented and Late-Pigmenting Rapidly Growing Mycobacteria in an Urban Tap Water Production and Distribution System

Nonpigmented and late-pigmenting rapidly growing mycobacteria (RGM) have been reported to commonly colonize water production and distribution systems. However, there is little information about the nature and distribution of RGM species within the different parts of such complex networks or about their clustering into specific RGM species communities. We conducted a large-scale survey between 2007 and 2009 in the Parisian urban tap water production and distribution system. We analyzed 1,418 water samples from 36 sites, covering all production units, water storage tanks, and distribution units; RGM isolates were identified by using rpoB gene sequencing. We detected 18 RGM species and putative new species, with most isolates being Mycobacterium chelonae and Mycobacterium llatzerense. Using hierarchical clustering and principal-component analysis, we found that RGM were organized into various communities correlating with water origin (groundwater or surface water) and location within the distribution network. Water treatment plants were more specifically associated with species of the Mycobacterium septicum group. On average, M. chelonae dominated network sites fed by surface water, and M. llatzerense dominated those fed by groundwater. Overall, the M. chelonae prevalence index increased along the distribution network and was associated with a correlative decrease in the prevalence index of M. llatzerense, suggesting competitive or niche exclusion between these two dominant species. Our data describe the great diversity and complexity of RGM species living in the interconnected environments that constitute the water production and distribution system of a large city and highlight the prevalence index of the potentially pathogenic species M. chelonae in the distribution network.     

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.     

Non Mycobacterial Virulence Genes in the Genome of the Emerging Pathogen Mycobacterium abscessus

Mycobacterium abscessus is an emerging rapidly growing mycobacterium (RGM) causing a pseudotuberculous lung disease to which patients with cystic fibrosis (CF) are particularly susceptible. We report here its complete genome sequence. The genome of M. abscessus (CIP 104536T) consists of a 5,067,172-bp circular chromosome including 4920 predicted coding sequences (CDS), an 81-kb full-length prophage and 5 IS elements, and a 23-kb mercury resistance plasmid almost identical to pMM23 from Mycobacterium marinum. The chromosome encodes many virulence proteins and virulence protein families absent or present in only small numbers in the model RGM species Mycobacterium smegmatis. Many of these proteins are encoded by genes belonging to a “mycobacterial” gene pool (e.g. PE and PPE proteins, MCE and YrbE proteins, lipoprotein LpqH precursors). However, many others (e.g. phospholipase C, MgtC, MsrA, ABC Fe(3+) transporter) appear to have been horizontally acquired from distantly related environmental bacteria with a high G+C content, mostly actinobacteria (e.g. Rhodococcus sp., Streptomyces sp.) and pseudomonads. We also identified several metabolic regions acquired from actinobacteria and pseudomonads (relating to phenazine biosynthesis, homogentisate catabolism, phenylacetic acid degradation, DNA degradation) not present in the M. smegmatis genome. Many of the “non mycobacterial” factors detected in M. abscessus are also present in two of the pathogens most frequently isolated from CF patients, Pseudomonas aeruginosa and Burkholderia cepacia. This study elucidates the genetic basis of the unique pathogenicity of M. abscessus among RGM, and raises the question of similar mechanisms of pathogenicity shared by unrelated organisms in CF patients.     

Evaluation of antimicrobial susceptibilities of rapidly growing mycobacteria by Sensititre RAPMYCO panel

This study used Sensititre RAPMYCO to test the activities of amikacin, cefoxitin, ciprofloxacin, clarithromycin, doxycycline, imipenem, linezolid, sulfamehoxazole, tigecycline and tobramycin against 25 clinical isolates of rapidly growing mycobacteria (RGM), including the common disease producing species Mycobacterium abscessus, Mycobacterium chelonae, Mycobacterium fortuitum and Mycobacterium peregrinum. Analysis of the four different RGM species showed that isolates of M. fortuitum and M. peregrinum were more susceptible than M. abscessus and M. chelonae. Different antimicrobials showed a variable sensitivity in all strains. Therefore, each species and strain must be individually evaluated, and it is always advisable to perform in vitro sensitivity tests before the treatment of infections due to RGM.     

Improved Identification of Rapidly Growing Mycobacteria by a 16S–23S Internal Transcribed Spacer Region PCR and Capillary Gel Electrophoresis

The identification of rapidly growing mycobacteria (RGM) remains problematic because of evolving taxonomy, limitations of current phenotypic methods and absence of a universal gene target for reliable speciation. This study evaluated a novel method of identification of RGM by amplification of the mycobacterial 16S–23S rRNA internal transcribed spacer (ITS) followed by resolution of amplified fragments by capillary gel electrophoresis (CGE). Nineteen American Type Culture Collection (ATCC) Mycobacterium strains and 178 clinical isolates of RGM (12 species) were studied. All RGM ATCC strains generated unique electropherograms with no overlap with slowly growing mycobacteria species, including M. tuberculosis. A total of 47 electropherograms for the 178 clinical isolates were observed allowing the speciation of 175/178 (98.3%) isolates, including the differentiation of the closely related species, M. massiliense (M. abscessus subspecies bolletii) and M. abscessus (M. abscessus sensu stricto). ITS fragment size ranged from 332 to 534 bp and 33.7% of clinical isolates generated electropherograms with two distinct peaks, while the remainder where characterized with a single peak. Unique peaks (fragment lengths) were identified for 11/12 (92%) RGM species with only M. moriokaense having an indistinguishable electropherogram from a rarely encountered CGE subtype of M. fortuitum. We conclude that amplification of the 16S–23S ITS gene region followed by resolution of fragments by CGE is a simple, rapid, accurate and reproducible method for species identification and characterization of the RGM.     

Mycobacterium abscessus ESX-3 plays an important role in host inflammatory and pathological responses during infection

Mycobacterial ESX systems are often related to pathogenesis during infection. However, little is known about the function of ESX systems of Mycobacterium abscessus (Mab). This study focuses on the Mab ESX-3 cluster, which contains major genes such as esxH (Rv0288, low molecular weight protein antigen 7; CFP-7) and esxG (Rv0287, ESAT-6 like protein). An esx-3 (MAB 2224c-2234c)-deletional mutant of Mab (Δesx) was constructed and used to infect murine and human macrophages. We then investigated whether Mab Δesx modulated innate host immune responses in macrophages. Mab Δesx infection resulted in less pathological and inflammatory responses. Additionally, Δesx resulted in significantly decreased activation of inflammatory signaling and cytokine production in macrophages compared to WT. Moreover, recombinant EsxG·EsxH (rEsxGH) proteins encoded by the ESX-3 region showed synergistic enhancement of inflammatory cytokine generation in macrophages infected with Δesx. Taken together, our data suggest that Mab ESX-3 plays an important role in inflammatory and pathological responses during Mab infection.     

High Isoniazid Resistance Rates in Rifampicin Susceptible Mycobacterium tuberculosis Pulmonary Isolates from Pakistan

Background

Rapid new diagnostic methods (including Xpert MTB/RIF assay) use rifampicin resistance as a surrogate marker for multidrug resistant tuberculosis. Patients infected with rifampicin susceptible strains are prescribed first line anti-tuberculosis therapy. The roll out of such methods raises a concern that strains with resistance to other first line anti-tuberculosis drugs including isoniazid will be missed and inappropriate treatment given. To evaluate implications of using such methods review of resistance data from high burden settings such as ours is essential.

Objective

To determine resistance to first line anti-tuberculosis drugs amongst rifampicin susceptible pulmonary Mycobacterium tuberculosis (MTB) isolates from Pakistan.

Materials and Methods

Data of pulmonary Mycobacterium tuberculosis strains isolated in Aga Khan University Hospital (AKUH) laboratory (2009–2011) was retrospectively analyzed. Antimicrobial susceptibility profile of rifampicin susceptible isolates was evaluated for resistance to isoniazid, pyrazinamide, ethambutol, and streptomycin.

Results

Pulmonary specimens submitted to AKUH from 2009 to 2011 yielded 7738 strains of Mycobacterium tuberculosis. These included 54% (n 4183) rifampicin susceptible and 46% (n: 3555) rifampicin resistant strains. Analysis of rifampicin susceptible strains showed resistance to at least one of the first line drugs in 27% (n:1133) of isolates. Overall isoniazid resistance was 15.5% (n: 649), with an isoniazid mono-resistance rate of 4% (n: 174). Combined resistance to isoniazid, pyrazinamide, and ethambutol was noted in 1% (n: 40), while resistance to isoniazid, pyrazinamide, ethambutol, and streptomycin was observed in 1.7% (n: 70) of strains.

Conclusions

Our data suggests that techniques (including Xpert MTB/RIF assay) relying on rifampicin susceptibility as an indicator for initiating first line therapy will not detect patients infected with MTB strains resistant to other first line drugs (including isoniazid). The roll out of these techniques must therefore be accompanied by strict monitoring ensuring early resistance detection to increase chances of improved patient outcomes.     

Comparative study with two different enrichments in the culture media used in the disinfectant efficacy assay

Recent changes in Brazilian legislation for commercial disinfectants have been published due to the recent epidemic of nosocomial infections caused by rapidly growing mycobacteria (RGM) in many states of Brazil over the last 8 years. One of these documents requires that all the manufacturers provide evidence of efficacy of sterilizing and disinfectant products, used for semi critical medical devices, against the Mycobacterium bovis BCG Moreau and Mycobacterium abscessus subsp. bolletii INCQS 00594 strains by using the Confirmative in vitro Test for Determining Tuberculocidal Activity of Disinfectants recommended by the Association of Official Analytical Chemists. These changes have caused additional costs and increased problems for importation of enrichment products at national laboratories where disinfectant efficacy assay service is performed. Middlebrook ADC Enrichment (ADC) is provided by a unique manufacturer and used in the official protocol. The aim of the present study was to evaluate an alternative in house low-cost enrichment composed of fetal bovine serum and glucose (FBSG) with ADC for performance of disinfectant efficacy assay against mycobacteria. After obtaining the growth curves for M. abscessus ATCC 19977, M. abscessus subsp. bolletii INCQS 00594, Mycobacterium chelonae ATCC 35752, and Mycobacterium fortuitum ATCC 6841 by using ADC enrichment and FBSG in Kirchners and 7H9 culture media. Through statistical analysis via the Kruskal-Wallis test on the evaluation of microorganism growth rate, it was observed that there was no inhibition of RGM growth by any of the enrichments used. These results suggest that low-cost enrichment FBSG may be used as a potential substitute of ADC for composition of media for mycobacterial growth, including in disinfectant tests.     

Relationships between Mycobacterium Isolates from Patients with Pulmonary Mycobacterial Infection and Potting Soils

High numbers of mycobacteria, including known pathogenic species such as Mycobacterium avium, Mycobacterium intracellulare, and Mycobacterium chelonae, were recovered from aerosols produced by pouring commercial potting soil products and potting soil samples provided by patients with pulmonary mycobacterial infections. The dominant mycobacteria in the soil samples corresponded to the dominant species implicated clinically. Profiles of large restriction fragments obtained by pulsed-field gel electrophoresis demonstrated a closely related pair of M. avium isolates recovered from a patient and from that patient's own potting soil. Thus, potting soils are potential sources of infection by environmental mycobacteria. Use of dust-excluding masks should be considered during potting or other activities that generate aerosol with soil.     

In vitro activity of SPR719 against Mycobacterium ulcerans,Mycobacterium marinum and Mycobacterium chimaera

Nontuberculosis mycobacterial (NTM) infections are increasing in prevalence across the world. In many cases, treatment options for these infections are limited. However, there has been progress in recent years in the development of new antimycobacterial drugs. Here, we investigate the in vitro activity of SPR719, a novel aminobenzimidazole antibiotic and the active form of the clinical-stage compound, SPR720, against several isolates of Mycobacterium ulcerans, Mycobacterium marinum and Mycobacterium chimaera. We show that SPR719 is active against these NTM species with a MIC range of 0.125–4 μg/ml and that this compares favorably with the commonly utilized antimycobacterial antibiotics, rifampicin and clarithromycin. Our findings suggest that SPR720 should be further evaluated for the treatment of NTM infections.     

Peptides derived from repulsive guidance molecule act as antagonists

Repulsive guidance molecule (RGM) is a membrane-bound protein that was originally identified as an axon guidance molecule in the visual system [T. Yamashita, B.K. Mueller, K. Hata, Neogenin and RGM signaling in the central nervous system, Curr. Opin. Neurobiol. 17 (2007) 29-34]. Functional studies in Xenopus and chick embryos have revealed the roles of RGM in axon guidance and laminar patterning, while those in mouse embryos have demonstrated its function in regulating the cephalic neural tube closure. Importantly, RGM inhibition enhanced the growth of injured axons and promoted functional recovery after spinal cord injury in rats. Here, we identified two RGMa-derived peptides that functioned as antagonists against RGMa. The peptides studied in vitro dose-dependently suppressed the neurite growth inhibition and growth cone collapse induced by RGMa. Thus, these peptides are promising reagents to treat injuries of the central nervous system.     

Draft genome sequence of Mycobacterium abscessus subsp. bolletii BD(T)

Mycobacterium abscessus subsp. bolletii is an increasing cause of human pulmonary disease and infections of the skin and soft tissues. Consistent reports of human infections indicate that M. bolletii is a highly pathogenic, emerging species of rapidly growing mycobacteria (RGM). Here we report the first whole-genome sequence of M. abscessus subsp. bolletii BD(T).     

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.     

Structural Insights into Putative Molybdenum Cofactor Biosynthesis Protein C (MoaC2) from Mycobacterium tuberculosis H37Rv

The Molybdenum cofactor (Moco) biosynthesis pathway is an evolutionary conserved pathway seen in almost all eukaryotes including the pathogenic species Mycobacterium tuberculosis. This pathway comprises of several novel reactions which include the initial formation of precursor Z from guanosine triphosphate (GTP), catalysed by two enzymes MoaA and MoaC. Although Moco biosynthesis is well understood, the first step is still not clear. In M. tuberculosis H37Rv, three orthologous genes of MoaC have been annotated: moaC1 (Rv3111), moaC2 (Rv0864) and moaC3 (Rv3324c). Rv0864 (MoaC2) is a 17.5 kDa protein and is reported to be down-regulated by ∼3 times in the nutrient starvation model for Mycobacterium tuberculosis. The crystal structure of Moco-biosynthesis protein MoaC2 from Mycobacterium tuberculosis (2.20 Å resolution, space group P2₁3) has been determined. Based on a comparative analysis of structures of homologous proteins, conserved residues were identified and are implicated in structural and functional roles. Molecular docking studies with probable ligands carried out in order to identify its ligand, suggests that pteridinebenzomonophosphate as the most likely ligand. Sequence based interaction study identified MoaA1 to interact with MoaC2. A homology model of MoaA1 was then complexed with MoaC2 and protein–protein interactions are also discussed.     

A Comparative Study of Mycobacteria from Patients' Room Dusts and from Sputa of Tuberculous Patients

The source of mycobacteria other than Mycobacterium tuberculosis occurring in sputa of tuberculous patients as casual isolates was investigated by comparing the occurrence rate of mycobacterial species between patient's room dust and patient's sputum. Almost all species of mycobacteria recovered from sputa could be found in dusts obtained from the rooms. However, the percentage of occurrence of the mycobacterial species in dusts differed from that in sputa. In dusts, Mycobacterium fortuitum (39.6%), Mycobacterium nonchromogenicum (23.5%) and Mycobacterium gordonae (16.7%) occurred in high frequencies, whereas Mycobacterium intracellulare (69.6%), M. gordonae (5.9%), Mycobacterium scrofulaceum (5.2%), and Gordona bronchialis (10.4%) were the main species found in sputa. The patterns of occurrence of mycobacterial species as illustrated above may suggest that pathogenic mycobacteria survive in the respiratory tract while nonpathogenic ones are destroyed there, thus the human body acts as a selective medium for the pathogenic mycobacterial species. Serotype studies on strains of M. intracellular as casual isolates indicated that those from sputa of tuberculous patients were different from those derived from patients with lung diseases due to this species of mycobacteria. These results led us to the conclusion that mycobacteria in patients' room dusts were the source of mycobacteria occurring in sputa as casual isolates, particularly the pathogenic mycobacteria in dusts are more likely to survive in the human respiratory tract, occasionally multiplying and causing disease under favorable circumstances.     

Successful outcomes with oral fluoroquinolones combined with rifampicin in the treatment of Mycobacterium ulcerans: an observational cohort study

Background

The World Health Organization currently recommends combined streptomycin and rifampicin antibiotic treatment as first-line therapy for Mycobacterium ulcerans infections. Alternatives are needed when these are not tolerated or accepted by patients, contraindicated, or neither accessible nor affordable. Despite in vitro effectiveness, clinical evidence for fluoroquinolone antibiotic use against Mycobacterium ulcerans is lacking. We describe outcomes and tolerability of fluoroquinolone-containing antibiotic regimens for Mycobacterium ulcerans in south-eastern Australia.

Methodology/Principal Findings

Analysis was performed of prospectively collected data including all primary Mycobacterium ulcerans infections treated at Barwon Health between 1998 and 2010. Medical treatment involved antibiotic use for more than 7 days; surgical treatment involved surgical excision of a lesion. Treatment success was defined as complete lesion healing without recurrence at 12 months follow-up. A complication was defined as an adverse event attributed to an antibiotic that required its cessation. A total of 133 patients with 137 lesions were studied. Median age was 62 years (range 3–94 years). 47 (34%) had surgical treatment alone, and 90 (66%) had combined surgical and medical treatment. Rifampicin and ciprofloxacin comprised 61% and rifampicin and clarithromycin 23% of first-line antibiotic regimens. 13/47 (30%) treated with surgery alone failed treatment compared to 0/90 (0%) of those treated with combination medical and surgical treatment (p<0.0001). There was no difference in treatment success rate for antibiotic combinations containing a fluoroquinolone (61/61 cases; 100%) compared with those not containing a fluoroquinolone (29/29 cases; 100%). Complication rates were similar between ciprofloxacin and rifampicin (31%) and rifampicin and clarithromycin (33%) regimens (OR 0.89, 95% CI 0.27–2.99). Paradoxical reactions during treatment were observed in 8 (9%) of antibiotic treated cases.

Conclusions

Antibiotics combined with surgery may significantly increase treatment success for Mycobacterium ulcerans infections, and fluoroquinolone combined with rifampicin-containing antibiotic regimens can provide an effective and safe oral treatment option.     

Comparative Genomic Analysis Reveals a Possible Novel Non-Tuberculous Mycobacterium Species with High Pathogenic Potential

Mycobacteria have been reported to cause a wide range of human diseases. We present the first whole-genome study of a Non-Tuberculous Mycobacterium, Mycobacterium sp. UM_CSW (referred to hereafter as UM_CSW), isolated from a patient diagnosed with bronchiectasis. Our data suggest that this clinical isolate is likely a novel mycobacterial species, supported by clear evidence from molecular phylogenetic, comparative genomic, ANI and AAI analyses. UM_CSW is closely related to the Mycobacterium avium complex. While it has characteristic features of an environmental bacterium, it also shows a high pathogenic potential with the presence of a wide variety of putative genes related to bacterial virulence and shares very similar pathogenomic profiles with the known pathogenic mycobacterial species. Thus, we conclude that this possible novel Mycobacterium species should be tightly monitored for its possible causative role in human infections.     

Diversity of Nontuberculoid Mycobacterium Species in Biofilms of Urban and Semiurban Drinking Water Distribution Systems

Nontuberculous mycobacteria (NTM) are ubiquitous and have been isolated from a variety of environmental sources, including water. Various NTM were isolated from biofilms in drinking water distribution systems in two urban and two semiurban areas in South Africa. Most of the isolates belonged to opportunistic pathogenic species of the NTM group, but none belonged to the Mycobacterium avium complex.     

In-vitro Activity of Avermectins against Mycobacterium ulcerans

Mycobacterium ulcerans causes Buruli ulcer (BU), a debilitating infection of subcutaneous tissue. There is a WHO-recommended antibiotic treatment requiring an 8-week course of streptomycin and rifampicin. This regime has revolutionized the treatment of BU but there are problems that include reliance on daily streptomycin injections and side effects such as ototoxicity. Trials of all-oral treatments for BU show promise but additional drug combinations that make BU treatment safer and shorter would be welcome. Following on from reports that avermectins have activity against Mycobacterium tuberculosis, we tested the in-vitro efficacy of ivermectin and moxidectin on M. ulcerans. We observed minimum inhibitory concentrations of 4–8 μg/ml and time-kill assays using wild type and bioluminescent M. ulcerans showed a significant dose-dependent reduction in M. ulcerans viability over 8-weeks. A synergistic killing-effect with rifampicin was also observed. Avermectins are well tolerated, widely available and inexpensive. Based on our in vitro findings we suggest that avermectins should be further evaluated for the treatment of BU.     

Resistome analysis of Mycobacterium tuberculosis: Identification of aminoglycoside 2'-Nacetyltransferase (AAC) as co-target for drug desigining

The emergence of multidrug resistant tuberculosis (MDRTB) highlights the urgent need to understand the mechanisms of resistance to the drugs and to develop a new arena of therapeutics to treat the disease. Ethambutol, isonazid, pyrazinamide, rifampicin are first line of drugs against TB, whereas aminoglycoside, polypeptides, fluoroquinolone, ethionamide are important second line of bactericidal drugs used to treat MDRTB, and resistance to one or both of these drugs are defining characteristic of extensively drug resistant TB. We retrieved 1,221 resistant genes from Antibiotic Resistance Gene Database (ARDB), which are responsible for resistance against first and second line antibiotics used in treatment of Mycobacterium tuberculosis infection. From network analysis of these resistance genes, 53 genes were found to be common. Phylogenetic analysis shows that more than 60% of these genes code for acetyltransferase. Acetyltransferases detoxify antibiotics by acetylation, this mechanism plays central role in antibiotic resistance. Seven acetyltransferase (AT-1 to AT-7) were selected from phylogenetic analysis. Structural alignment shows that these acetyltransferases share common ancestral core, which can be used as a template for structure based drug designing. From STRING analysis it is found that acetyltransferase interact with 10 different proteins and it shows that, all these interaction were specific to M. tuberculosis. These results have important implications in designing new therapeutic strategies with acetyltransferase as lead co-target to combat against MDR as well as Extreme drug resistant (XDR) tuberculosis.

Abbreviations

AA - amino acid, AT - Acetyltransferase, AAC - Aminoglycoside 2''-N-acetyltransferase, XDR - Extreme drug-resistant, MDR - Multidrug-resistant, Mtb - Mycobacterium tuberculosis, TB - Tuberculosis.