Background Rapid molecular diagnostics for detecting multidrug-resistant and extensively drug-resistant tuberculosis (M/XDR-TB) primarily identify mutations in Mycobacterium tuberculosis ( Mtb ) genes associated with drug resistance. Their accuracy, however, is dependent largely on the strength of the association between a specific mutation and the phenotypic resistance of the isolate with that mutation, which is not always 100%. While this relationship is well established and reliable for first-line anti-TB drugs, rifampin and isoniazid, it is less well-studied and understood for second-line, injectable drugs, amikacin (AMK), kanamycin (KAN) and capreomycin (CAP). Methodology/Principal Findings We conducted a systematic review of all published studies evaluating Mtb mutations associated with resistance to AMK, KAN, CAP in order to characterize the diversity and frequency of mutations as well as describe the strength of the association between specific mutations and phenotypic resistance in global populations. Our objective was to determine the potential utility and reliability of these mutations as diagnostic markers for detecting AMK, KAN and CAP resistance. Mutation data was reviewed for 1,585 unique clinical isolates from four continents and over 18 countries. Mutations in the rrs , tlyA , eis promoter and gidB genes were associated with AMK, KAN and/or CAP resistance. Conclusions/Significance The rrs A1401G mutation was present in the majority of AMK, KAN and CAP resistant Mtb strains reviewed, but was also found in 7% of CAP susceptible strains. The 1401 mutation alone, however, was not found with sufficient frequency to detect more than 70–80% of global Mtb strains resistant to AMK and CAP, and 60% of strains resistant to KAN. Additional mutations in the rrs , eis promoter, tlyA and gidB genes appear to be associated with resistance and could improve sensitivity and specificity of future diagnostics.

BackgroundIntestinal parasitic nematode diseases are one of the great diseases of our time. Intestinal roundworm parasites, including hookworms, whipworms, and Ascaris, infect well over 1 billion people and cause significant morbidity, especially in children and pregnant women. To date, there is only one drug, albendazole, with adequate efficacy against these parasites to be used in mass drug administration, although tribendimidine may emerge as a second. Given the hundreds of millions of people to be treated, the threat of parasite resistance, and the inadequacy of current treatments, new anthelmintics are urgently needed. Bacillus thuringiensis (Bt) crystal (Cry) proteins are the most common used biologically produced insecticides in the world and are considered non-toxic to vertebrates.Methods/Principal FindingsHere we study the ability of a nematicidal Cry protein, Cry5B, to effect a cure in mice of a chronic roundworm infection caused by the natural intestinal parasite, Heligmosomoides bakeri (formerly polygyrus). We show that Cry5B produced from either of two Bt strains can act as an anthelmintic in vivo when administered as a single dose, achieving a ∼98% reduction in parasite egg production and ∼70% reduction in worm burdens when delivered per os at ∼700 nmoles/kg (90–100 mg/kg). Furthermore, our data, combined with the findings of others, suggest that the relative efficacy of Cry5B is either comparable or superior to current anthelmintics. We also demonstrate that Cry5B is likely to be degraded quite rapidly in the stomach, suggesting that the actual dose reaching the parasites is very small.Conclusions/SignificanceThis study indicates that Bt Cry proteins such as Cry5B have excellent anthelmintic properties in vivo and that proper formulation of the protein is likely to reveal a superior anthelmintic.

Increasingly complex drug-resistant tuberculosis (DR-TB) is a major global health concern and one of the primary reasons why TB is now the leading infectious cause of death worldwide. Rapid characterization of a DR-TB patient's complete drug resistance profile would facilitate individualized treatment in place of empirical treatment, improve treatment outcomes, prevent amplification of resistance, and reduce the transmission of DR-TB. The use of targeted next-generation sequencing (NGS) to obtain drug resistance profiles directly from patient sputum samples has the potential to enable comprehensive evidence-based treatment plans to be implemented quickly, rather than in weeks to months, which is currently needed for phenotypic drug susceptibility testing (DST) results. In this pilot study, we evaluated the performance of amplicon sequencing of Mycobacterium tuberculosis DNA from patient sputum samples using a tabletop NGS technology and automated data analysis to provide a rapid DST solution (the Next Gen-RDST assay). One hundred sixty-six out of 176 (94.3%) sputum samples from the Republic of Moldova yielded complete Next Gen-RDST assay profiles for 7 drugs of interest. We found a high level of concordance of our Next Gen-RDST assay results with phenotypic DST (97.0%) and pyrosequencing (97.8%) results from the same clinical samples. Our Next Gen-RDST assay was also able to estimate the proportion of resistant-to-wild-type alleles down to mixtures of ≤1%, which demonstrates the ability to detect very low levels of resistant variants not detected by pyrosequencing and possibly below the threshold for phenotypic growth methods. The assay as described here could be used as a clinical or surveillance tool.

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Objective To correlate rrs and eis promoter mutations, found in Mycobacterium tuberculosis (MTB) isolates,with corresponding Minimum Inhibitory Concentrations (MICs) of amikacin (AMK), kanamycin (KAN), and capreomycin (CAP). Methods Ninety MTB clinical isolates were analyzed in this study. MICs were determined by MGIT 960 for 59 isolates with resistance-associated mutations in the rrs and eis promoter gene regions and 31 isolates with wild-type sequences, as determined by the GenoTypeMTBDRsl (version 1) assay. Results The rrs A1401G mutation was identified in 48 isolates resistant to the second line injectables. The eis promoter mutations C-14T (n=3), G-10C (n=3), G-10A (n=3), and C-12T (n=2) were found within 11 isolates with various resistance profiles to the second line injectables. Thirty-one isolates had wild-type sequences for the rrs and eis promoter gene regions of interest, one of which was AMK, KAN and CAP-resistant. Isolates with the A1401G rrs mutation had AMK, KAN, and CAP MICs of >40, >20, and 5–15mg/L, respectively. Isolates with eis promoter mutations had AMK, KAN, and CAP MICs of 0. 25–1. 0, 0. 625–10, and 0. 625–2. 5mg/L, respectively. Conclusions This study provides a preliminary basis for the prediction of phenotypic resistance levels to the second line injectables based upon the presence of genetic mutations associated with AMK, KAN and CAP-resistance. Results suggest that isolates with eis promoter mutations have consistently lower resistance levels to AMK, KAN, and CAP than isolates with the rrs A1401G mutation.