Balaji Veeraraghavan

High burden of antimicrobial drug resistance in Asia

The rapid development of antimicrobial resistance among micro-organisms is a serious public health concern. Moreover, the dissemination of antibiotic-resistant bacteria makes this issue a global problem, and Asia is no exception. For example, since New Delhi metallo-β-lactamase (NDM)-producing Enterobacteriaceae were identified in India, further spread of NDM has become a worldwide threat. However, the epidemiology of antibiotic-resistant bacteria in Asia may be different to other regions, and clinical condition may be worse than in western countries. Antibiotic-resistant bacteria, including community-acquired and hospital-acquired meticillin-resistant Staphylococcus aureus (MRSA), vancomycin-intermediate S. aureus (VISA), vancomycin-resistant enterococci, macrolide- and penicillin-resistant Streptococcus pneumoniae, extend-spectrum β-lactamase (ESBL)-producing Escherichia coli and Klebsiella pneumoniae, carbapenem-resistant Enterobacteriaceae, and multidrug-resistant Pseudomonas aeruginosa and Acinetobacter spp., are becoming prevalent in many countries in Asia. Moreover, the prevalence of each antibiotic-resistant bacterium in each country is not identical. This review provides useful information regarding the critical condition of antibiotic resistance in Asia and emphasises the importance of continuous surveillance of resistance data.

Invasive pneumococcal disease associated with high case fatality in India

OBJECTIVE To study the seroepidemiology and antimicrobial resistance pattern of invasive pneumococcal disease (IPD) in older subjects who are admitted to hospitals in India. STUDY DESIGN AND SETTING Prospective surveillance of IPD in patients older than 18 years in seven large academic teaching hospitals in India from 1993 to 2008. All subjects who had Streptococcus pneumoniae isolated from normally sterile body fluids or were antigen positive in cerebrospinal fluid, ascitic fluid, and pleural fluid were identified as IPD cases in the study. Serotype/group (STG) and minimum inhibitory concentration for penicillin, chloramphenicol, co-trimoxazole (trimethoprim-sulfamethoxazole), erythromycin, and cefotaxime were determined. RESULTS A total of 1,037 adult subjects with suspected invasive bacterial infection were recruited in the study. S pneumoniae was identified from normally sterile body fluids in 449 (43.3%) subjects. Meningitis (34.3%) and pneumonia (33.9%) were the most common clinical conditions associated with IPD. The case fatality was 25-30% across all age groups. Penicillin resistance was low at 2.7% overall. Resistance to co-trimoxazole was noted to be high and increasing in the study period from 42.9% in 1993 to 85.2% in 2008 (P = 0.001). The most common STG was serotype 1, which accounted for 22.9% of all isolates. The 23-valent pneumococcal polysaccharide vaccine covered 83.3% of the STGs (49/54; 95% confidence interval: 79.7, 96.9) for patients older than 60 years. CONCLUSION IPD continues to be a problem in India and is associated with high case fatality in spite of treatment in the hospital setting. Penicillin resistance is currently low in India. More than 80% of invasive STGs causing disease in the elderly in India are included in the formulation of polysaccharide pneumococcal vaccine.

Rapid Screening for Carbapenem Resistant Organisms: Current Results and Future Approaches

Carbapenem producing Enterobacteriaceae (CPE) is a major public health threat. A total of 120 carbapenem resistant E.coli (n=32) and K.pneumoniae (n=88) from blood stream infections were screened for the presence of carbapenem resistant genes KPC, NDM, IMP, VIM, and OXA-48 like using both conventional multiplex PCR and Xpert(®) Carba-R test. Additionally 26 faeces samples were directly screened with Xpert(®) Carba-R test. Of the tested isolates, 40% (n=48) of NDM and 39.2% (n=47/) of OXA-48-like were identified. Co-production of OXA-48 and NDM was seen in 15 (12.5%) isolates. In Xpert(®) Carba-R test, only NDM was identified in 55% (n=66) of tested isolates. Of the tested faeces samples, 12 were identified as carbapenemase producers: nine with NDM, two with the co-production of NDM and VIM and in Klebsiella spp (n=1), NDM and KPC co-production was seen. However, Xpert(®) Carba-R test fails to detect OXA-48 like as compared with multiplex PCR. The sensitivity, specificity, PPV, NPV of Xpert(®) Carba-R test was 100%, 77%, 96% and 100% respectively. Incorporation of OXA-48 like specific sequence in the panel of Xpert(®) Carba-R test may improve its sensitivity and maximize the coverage of assay.

Laboratory detection and clinical implication of oxacillinase-48 like carbapenemase: The hidden threat

Carbapenemase producing Gram-negative pathogen is of great concern for physician. The challenging aspects are treatment option and infection control. Monitoring of respective carbapenemase resistance mechanism is necessary to prevent the outbreaks. Currently, the rapid emergence of oxacillinase (OXA-48) like is alarming. Increasing frequency of OXA-48 is seen than the classical carbapenemase (KPC, NDM, IMP, and VIM) across the world. The blaOXA-48 gene is commonly identified in Escherichia coli and Klebsiella pneumoniae. The transferrable plasmid of OXA-48 is associated with rapid spread and inter-species dissemination. In general, OXA-48-like enzymes weakly hydrolyzes both carbapenem and broad spectrum cephalosporins. Except OXA-163, which effectively hydrolyze cephalosporin. This poor hydrolytic profile obscures the detection of OXA-48-like. It may go undetected in routine diagnosis and complicates the treatment option. Co-production of OXA-48-like with CTX-M-15 and other carbapenemase (NDM, VIM) leads to the emergence of multidrug resistant strains.

Haemophilus parainfluenzae: report of an unusual cause of neonatal sepsis and a literature review

Haemphilus parainfluenzae, an unusual cause of early-onset neonatal sepsis, is rarely reported. Risk factors for this serious infection include prolonged rupture of membranes, choriamnionitis, and prematurity. A high index of suspicion, proper culture techniques, and rapid species identification are needed to diagnose H. parainfluenzae sepsis. We present the first documented case from India with a review of the literature.

MDR- and XDR-TB among suspected drug-resistant TB patients in a tertiary care hospital in India

Aim:  To study the anti‐tubercular drug resistance pattern among suspected cases of drug‐resistant TB.

Molecular Mechanisms of Colistin Resistance in Klebsiella pneumoniae Causing Bacteremia from India—A First Report

Colistin has long been a reserve drug used for the treatment of carbapenem resistant Klebsiella pneumoniae. Carbapenem resistance in K. pneumoniae has been increasing and is as high as 44% in India. Although a reserve agent, with rise in rates of resistance to carbapenems, the usage of colistin has increased over the years leading to slow emergence of resistance. Colistin resistance is mainly mediated by the alteration in the LPS of bacterial outer membrane with the addition of L-Ara4-N and PEtN molecules. These alterations are mediated by mutations in several genes involved in lipidA modifications and most commonly mutations in mgrB gene has been reported. Recently there is emergence of plasmid mediated resistance due to mcr-1 and mcr-2 genes which poses a threat for the rapid global spread. This study aims at characterizing eight colistin resistant K. pneumoniae from bacteremia by whole genome sequencing. Eight K. pneumoniae were isolated from blood culture during 2013 and 2014 at the Department of Clinical Microbiology, Christian Medical College, India. Antimicrobial susceptibility testing was performed and minimum inhibitory concentration (MIC) was determined for colistin and polymyxin B by broth-micro dilution method. Whole genome sequencing was performed using Ion Torrent and the genome of all eight isolates was analyzed. The eight isolates were resistant to all the antimicrobials expect tigecycline. MIC of colistin and polymyxin B were ranged from 4 to 1024 μg/ml and 0.5 to 2048 μg/ml respectively. Multiple mutations were observed in the chromosomal genes involved in lipid A modifications. mcr-1 and mcr-2 gene was absent in all the isolates. The most significant were mutations in mgrB gene. Among the eight isolates, four, three and one were belonged to sequence types ST 231, ST14 and ST147 respectively. Seven isolates had blaOXA−48 like, one co-expressed blaNDM−1 and blaOXA−48 like genes leading to carbapenem resistance. Overall, multiple numbers of alterations have been observed. This includes silent mutations, point mutations, insertions and/or deletions. Mutations in mgrB gene is responsible for resistance to colistin in this study. Due to emergence of resistance to reserve drugs, there is a need for combination therapies for carbapenem resistant K. pneumoniae and colistin must be judiciously used.

Draft Genome Sequences of Three Hypervirulent Carbapenem-Resistant Klebsiella pneumoniae Isolates from Bacteremia

ABSTRACT Hypervirulent Klebsiella pneumoniae strains have been increasingly reported worldwide, and there is emergence of carbapenem resistance among them. Here, we report the genome sequences of three carbapenem-resistant hypervirulent K. pneumoniae isolates isolated from bacteremic patients at a tertiary-care center in South India.

Draft genome sequence of blaTEM-1-mediated cephalosporin-resistant Salmonella enterica serovar Typhi from bloodstream infection

Enteric fever is a major cause of concern in developing countries across the globe. The primary choice of antibiotics remains fluoroquinolones, followed by cephalosporins. Resistance to third-generation cephalosporins is rarely reported in Salmonella enterica serovar Typhi. This study reports the whole genome sequence of an S. Typhi isolate resistant to cefixime [minimum inhibitory concentration (MIC)=512μg/mL] by microbroth dilution. Interestingly, the isolate was negative for the cephalosporin resistance gene blaCTX-M by PCR, which is a known mechanism for higher cephalosporin resistance. The isolate was further subjected to next-generation sequencing that identified blaTEM-1B and blaDHA-1 genes in association with qnrB4 and sul1. blaTEM is a known gene coding for β-lactam resistance. In certain cases, overexpression of blaTEM was reported to result in cephalosporin resistance. This suggests that the high cefixime MIC would have been contributed by overexpression of blaTEM-1B. The blaTEM-1B gene was found to be associated with a promoter Px with -35 and -10 regions as TTAATA and TAAAGT, respectively. The promoter regions were unique, but the -10 region was similar to that found in Pa/Pb (previously reported promoter for blaTEM) with a single nucleotide change. In addition, an IncN plasmid was identified, which is usually reported in association with the most prevalent extended-spectrum β-lactamase (ESBL), metallo- and non-metallo-carbapenemase, and plasmid-mediated quinolone resistance (PMQR) genes. Plasmids such as IncN might possibly confer resistance and enhance spread. It is imperative to continuously monitor the drug resistance profile and evolving genetic elements.

Group A rotavirus gastroenteritis in older children and adults at a hospital in southern India.

There is limited data on the spectrum and prevalence of rotavirus genotypes in older children and adults in Asia. This pilot study conducted between November 2012 and April 2013 tested for rotavirus in older children (>12 years of age), and adults with gastroenteritis from southern India. Stool samples from patients who were hospitalized or attended out-patient units with diarrhea were screened for rotavirus using Premier™ Rotaclone(®). Confirmatory testing was by another antigen detection sandwich, in-house ELISA, based on capture by a polyclonal serum and VP6 PCR. Genotyping for VP7 and VP4 was done using hemi-nested PCRs for G- and P-types circulating in India. A total of 626 stool samples from older children and adults were screened and 52 (8.4%) were initially positive for rotavirus by antigen detection. A high proportion of samples (27/51) were found to be false positives on confirmatory testing. Of the 23 samples for which genotyping results were obtained, G1P[8] was the most common genotype. There was one each of G1P[6], G1P[4] and two strains of G9P[4] while one sample showed mixed genotypes of G2 and G9P[4]. This study shows that group A rotavirus is found in 3.8% of diarrheal specimens in older children and adults with gastroenteritis in southern India and that common genotypes circulate in children and adults.