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Aim: To evaluate the performance of VITEK®MS with DNA sequencing for laboratory diagnosis of non-tuberculous mycobacteria (NTM) species in a resource-limited setting. Methods: 16SrRNA sequencing and MALDI-TOF mass spectrometry (VITEK®MS) was performed at a tertiary-care hospital in India. MALDI-TOF results were confirmed by 16S rRNA sequencing. In addition, sequencing of the internal transcribed spacer region was performed on slowly growing NTM. Results: Commonest species isolated were M. abscessus, M. intracellulare, M. avium, M. fortuitum and M. simiae. 16S rRNA sequencing and MALDI-TOF results had agreement of 94.5% for rapidly growing and 77.5% for slowly growing NTM. Conclusion: There is good correlation between VITEK®MS and sequencing for rapidly growing NTM. For slowly growing species, sequencing would be required in a third isolates.

Aim: To determine the presence of vancomycin heteroresistance in Staphylococcus haemolyticus ., Materials & Methods: A total of 48 rifampicin-resistant S. haemolyticus isolates from bloodstream infections were included. Vancomycin heteroresistance was determined using the population analysis profile-area under curve (PAP-AUC) method. All the isolates were screened for the presence of mec A gene, mutations in the rpo B gene, staphylococcal cassette chromosome  mec and multilocus sequence types., Results: Fifteen isolates were identified as heteroresistant vancomycin-intermediate S. haemolyticus  using PAP-AUC method. Dual rpo B mutations (D471E and I527M) contributed for the rifampicin resistance. The sequence types of heteroresistant vancomycin-intermediate S. haemolyticus were highly diverse., Conclusion: These findings illustrate the potential of  S. haemolyticu s to develop heteroresistance, which emphasizes the need for routine surveillance of S. haemolyticus isolated from intensive care units for infection control practices., Competing Interests: Financial & competing interests disclosure The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties. No writing assistance was utilized in the production of this manuscript., (© 2021 Balaji Veeraraghavan.)

Aim: To evaluate the antibacterial activity of fosfomycin-meropenem and fosfomycin-colistin combinations against carbapenem-resistant Klebsiella pneumoniae (CR-Kp)., Methods: A total of 50 CR-Kp isolates recovered from blood cultures were included in this study. All the CR-Kp isolates were screened for the presence of carbapenem resistant genes bla IMP . bla VIM . bla NDM . bla OXA-48 like, bla KPC . bla GES .#x00A0;and bla SPM . Combination testing of fosfomycin-meropenem and fosfomycin-colistin were performed using time-kill assay., Results: Fosfomycin-meropenem combination showed synergy in 20% of the tested CR-Kp isolates. While, fosfomycin-colistin exhibited synergy against 16% of the isolates. A total of 68% (n = 34) of CR-Kp isolates were characterised as OXA-48-like producers and 22% (n = 11) as NDM producers. Synergistic activity of these combinations was observed against OXA-48, NDM and NDM + OXA-48 co-producers., Conclusion: Considerable synergistic antibacterial activity of fosfomycin-meropenem and fosfomycin-colistin was not observed against CR-Kp isolates. Therefore, these combinations may not be promising for infections associated with CR-Kp., Competing Interests: Financial & competing interests disclosure The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties. No writing assistance was utilized in the production of this manuscript., (© 2020 Balaji Veeraraghavan.)

Aim: Shigella species has varying levels of virulence gene expression with respect to different sites of infection. In this study, the differential gene expression of S. dysenteriae in response to its site of infection was analyzed by transcriptomics., Methods: This study includes four clinical Shigella isolates. Transcriptomics was done for the stool and blood samples of a single patient. Isolates were screened for the presence of antimicrobial resistance genes., Results: The majority of genes involved in invasion were highly expressed in the strain isolated from the primary site of infection. Additionally, antimicrobial resistance ( dhfr 1A, sul II, bla OXA . bla CTX-M-1 and qnr S) genes were identified., Conclusion: This study provides a concise view of the transcriptional expression of clinical strains and provides a basis for future functional studies on Shigella spp., Competing Interests: Financial & competing interests disclosure The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties. No writing assistance was utilized in the production of this manuscript., (© 2020 Balaji Veeraraghavan.)

Acinetobacter species have emerged as one of the most clinically important pathogens. The phenotypic techniques which are currently available are insufficient in accurately identifying and differentiating the closely related and clinically important Acinetobacter species. Here, we discuss the advantages and limitations of the conventional phenotypic methods, automated identification systems, molecular methods and MALDI-TOF in the precise identification and differentiation of Acinetobacter species. More specifically, several species of this genus are increasingly reported to be of high clinical importance. Molecular characterization such as of bla OXA-51 -like PCR together with rpoB sequencing has high discriminatory power over the conventional methods for Acinetobacter species identification, especially within the Acinetobacter calcoaceticus-Acinetobacter baumannii complex., Competing Interests: Financial & competing interests disclosure The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties. No writing assistance was utilized in the production of this manuscript.

Aim: To investigate antimicrobial resistance mechanisms in a cluster of colistin-resistant Klebsiella pneumoniae ., Methods: Antimicrobial susceptibility was tested by disk diffusion and broth microdilution. Whole-genome sequencing and genome analysis were performed., Results: The eight colistin-resistant K. pneumoniae isolates belonged to three different clones (ST11, 14 and 231). The eptA and arnT genes from lipid modification pathway had novel (R157S in arnT and Q319R in eptA ) and rare mutations (V39L, R152H, S260L and A279G in eptA ). Several substitutions were also identified in mgrB , pmrB , phoP and phoQ genes. The mcr genes were absent in all isolates. Isolates had variants from existing classes of fosA gene., Conclusion: Complex combination of mutations might have led to colistin resistance, which suggests that continuous surveillance of molecular mechanisms is required., Competing Interests: Financial & competing interests disclosure The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties. No writing assistance was utilized in the production of this manuscript.

Multidrug-resistant Salmonella enterica subsp. enterica serovar Typhi (resistant to ampicillin, chloramphenicol and cotrimoxazole), was significantly reduced with the increased usage of fluoroquinolones and azithromycin. This has led to declining multidrug resistance rates in India with increasing ciprofloxacin nonsusceptibility rates and clinical failures due to azithromycin. However, for the available agents such as ceftriaxone, azithromycin and fluoroquinolones, the dose and duration for treatment is undefined. The ongoing clinical trials for typhoid management are expected to recommend the defined dose and duration for better clinical outcome. We made an attempt to summarize the issues in laboratory detection, treatment options and responses, and the concerns in clinical practice seen in the developing countries., Competing Interests: Financial & competing interests disclosure The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties. No writing assistance was utilized in the production of this manuscript.