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Introduction- The increasing antibiotic resistance like advent of carbapenem resistant Enterobactarales (CRE), Carbapenem Resistant Acinetobacter baumanii (CRAB) and Carbapenem Resistant Pseudomonas aeruginosa (CRPA) has led to use of toxic and older drugs like colistin for these organisms. But worldwide there is an increase in resistance even to colistin mediated both by chromosomes and plasmids. This necessitates accurate detection of resistance. This is impeded by unavailability of a user friendly phenotypic method for use in routine clinical microbiology practice. The present study attempts to evaluate two different methods- Colistin broth disc elution and MIC detection by Vitek 2 in comparison to CLSI approved broth microdilution (BMD) for colistin for Enterobactarales, Pseudomonas aeruginosa and Acinetobacter baumanii clinical isolates. Methods- Colistin susceptibility of 6013 carbapenem resistant isolates was determined by BMD, Colistin Broth Disc Elution (CBDE) and Vitek2 methods and was interpreted as per CLSI guidelines. The MIC results of CBDE, Vitek 2 were compared with that of BMD and essential agreement (EA), categorical agreement (CA), sensitivity, specificity, very major error (VME), major error (ME) and cohen’s kappa (CK) was calculated. Presence of any plasmid-mediated colistin resistance (mcr-1, 2, 3, 4 and 5) was evaluated all colistin resistant isolates by conventional polymerase chain reaction. Results- Colistin resistance was found in 778 (12.9%) strains among the carbapenem resistant isolates. Klebsiella pneumoniae had the highest (18.9%) colistin resistance by BMD method. MIC of Vitek 2 had sensitivity ranging from 78.2% to 84.8% and specificity of > 92%. There were 171 VMEs and 323 MEs by Vitek2 method, much more than CLSI acceptable range. The highest percentage of errors was committed for Acinetobacter baumanii (27.8% of VME and 7.9% ME). On the other hand the CBDE method performed well with EA, CA, VME and ME within acceptable range for all the organisms. The sensitivity of CBDE method compared to gold standard BMD varied from 97.5%-98.8% for different strains with a specificity of more than 97.6%. None of the isolated colistin resistant organism harbored mcr plasmids. Conclusion- As BMD has many technical complexities, CBDE is the best viable alternative available for countries like India. A sensitive MIC reported by Vitek2 needs to be carefully considered due high propensity for VMEs particularly for Klebsiella spp. Data summary- Supplementary material provides data regarding the comparison of MICs of three different mmethods for all samples. Sheet 1 to Sheet 5 contains data for E.coli, K.pneumoniae, A.baumannii, P.aeruginosa, E. cloacae respectively.

Objective: To investigate the prevalence of isolated organisms in patients with lower respiratory tract infections and the antibiotic susceptibilities at a tertiary care center. Methods: In this observational and cross-sectional analysis, 114 patients admitted in the intensive care unit were enrolled. The endotracheal aspirates and bronchoalveolar lavage were collected. The bacteria were isolated and identified, and finally, antimicrobial sensitive pattern of the isolated bacteria was examined. Results: The prevalence of infection was 72.72% in male patients and 27.28% in females. The predominant bacteria were Klebsiella pneumoniae (37.50%) followed by Acinetobacter spp. (36.36%), Pseudomonas aeruginosa (7.95%), Escherichia coli (6.81%), Proteus mirabilis (2.27%), atypical Escherichia coli (1.13%), Enterococcus spp. (1.13%), Elizabethkingia meningoseptica (1.13%), Staphylococcus aureus (1.13%), Proteus vulgaris (1.13%), Citrobacter freundii (1.13%), and Citrobacter koseri (1.13%). High resistance to cephalosporins (82.18%) was demonstrated in all Gram-negative bacteria. Bacteria showed susceptibility to colistin (88.75%) followed by tigecycline (83.11%), gentamycin (36.18%), and amikacin (49.23%). Conclusions: As the most frequent respiratory organisms, Klebsiella pneumoniae and Acinetobacter spp. have increased resistance to cephalosporins and susceptibility to colistin followed by tigecycline.

The emergence of colistin-carbapenem-resistant Klebsiella pneumoniae (CCR-Kp) in bloodstream infection results in high mortality, and virulence factor contributes further to the difficulty of treatment. A total of 158 carbapenem-resistant K. pneumoniae (CRKP) isolates causing bloodstream infection were collected from three Indian tertiary care hospitals during the 9-month study period, of which 27 isolates exhibited resistance to both colistin and carbapenem antibiotics. In this study, all the strains were characterized for antimicrobial resistance, virulence factors and capsular serotypes that facilitate the development of colistin and carbapenem-resistant K.pneumoniae (CCR-Kp) in bloodstream infection. Fourteen isolates displayed extremely drug resistance (XDR), susceptible only to tigecycline, and the remaining 13 isolates displayed multidrug resistance (MDR). The gene prevalence analysis for CCR-Kp isolates showed the predominance of bla(KPC) (81.48%) followed by bla(NDM) (62.96%), bla(VIM) (37.03%) and bla(IMP) (18.51%) genes. The distribution of virulence genes was found to be fimH (81.48%), wabG (59.25%), mrkD (55.56%), entB (48.15%), irp1 (33.33%), and rmpA (18.52%). The capsular serotypes K1, K2, K5 and K54 have been identified in 16 isolates. The absence of plasmid-mediated colistin resistance (mcr) genes implies the involvement of other mechanisms. The ERIC and (GTG)(5) molecular typing methods detected 18 and 22 distinct clustering patterns among the CCR-Kp isolates, respectively. A strong correlation between ERIC and (GTG)5 genotyping method was established with antimicrobial resistance patterns and virulence determinants at P

Chromobacterium violaceum, a facultative anaerobic proteobacterium, is particularly isolated from water and soil in tropical areas and has been implicated in few infections like septicemia, visceral abscesses, skin and soft tissue infections, meningitis and diarrhea. But urinary tract infection caused by it is very rare. Limited awareness about this pathogen and inappropriate antibiotic therapy contribute to a high mortality rate. Here, we describe an unusual case of urinary tract infection by Chromobacterium violaceum in a young immuno-competent male which was managed aggressively with proper antibiotics as per the culture sensitivity report.