Clinical and Genomic Evolution of Carbapenem-Resistant Klebsiella pneumoniae Bloodstream Infections over Two Time Periods at a Tertiary Care Hospital in South India: A Prospective Cohort Study.

INTRODUCTION: The objective of this study was to examine the evolution of carbapenem-resistant Klebsiella pneumoniae (CRKp) infections and their impact at a tertiary care hospital in South India. METHODS: A comparative analysis of clinical data from two prospective cohorts of patients with CRKp bacteremia (C1, 2014-2015; C2, 2021-2022) was carried out. Antimicrobial susceptibilities and whole genome sequencing (WGS) data of selected isolates were also analyzed. RESULTS: A total of 181 patients were enrolled in the study, 56 from C1 and 125 from C2. CRKp bacteremia shifted from critically ill patients with neutropenia to others (ICU stay: C1, 73%; C2, 54%; p = 0.02). The overall mortality rate was 50% and the introduction of ceftazidime-avibactam did not change mortality significantly (54% versus 48%; p = 0.49). Oxacillinases (OXA) 232 and 181 were the most common mechanisms of resistance. WGS showed the introduction of New Delhi metallo-ß-lactamase-5 (NDM-5), higher genetic diversity, accessory genome content, and plasmid burden, as well as increased convergence of hypervirulence and carbapenem resistance in C2. CONCLUSIONS: CRKp continues to pose a significant clinical threat, despite the introduction of new antibiotics. The study highlights the evolution of resistance and virulence in this pathogen and the impact on patient outcomes in South India, providing valuable information for clinicians and researchers.

Persistent bacteremia predicts poor outcomes among neutropenic patients with carbapenem-resistant gram-negative bloodstream infections receiving appropriate therapy.

PURPOSE: Identifying persistent bacteremia early in patients with neutropenia may improve outcome. This study evaluated the role of follow-up blood cultures (FUBC) positivity in predicting outcomes among patients with neutropenia and carbapenem-resistant gram-negative bloodstream infections (CRGNBSI). METHODS: This retrospective cohort study conducted between December 2017 and April 2022 included patients more than 15 years old with neutropenia and CRGNBSI, who survived for ≥ 48 h, receiving appropriate antibiotic therapy and had FUBCs. Patients with polymicrobial bacteremia within 30 days were excluded. The primary outcome was 30 day mortality. Persistent bacteremia, septic shock, recovery from neutropenia, prolonged or profound neutropenia, requirement of intensive care and dialysis, and initiation of appropriate empirical therapy were also studied. RESULTS: In our study cohort of 155 patients, the 30 day mortality rate was 47.7%. Persistent bacteremia was common in our patient cohort (43.8%). Carbapenem resistant isolates identified in the study were K.pneumoniae (80%), E.coli (12.26%), P.aeruginosa (5.16%), A.baumanii (1.94%) and E.cloacae (0.65%). The median time for sending a FUBC was 2 days (IQR, 1-3 days). Patients with persistent bacteremia had higher mortality than those without (56.76% versus 32.1%; p < 0.001). Appropriate initial empirical therapy was given to 70.9%. Recovery from neutropenia occurred in 57.4% while 25.8% had prolonged or profound neutropenia. Sixty-nine percent (107/155) had septic shock and needed intensive care; 12.2% of patients required dialysis. Non-recovery from neutropenia (aHR, 4.28; 95% CI 2.53-7.23), presence of septic shock (aHR, 4.42; 95%CI 1.47-13.28), requirement of intensive care (aHR,3.12;95%CI 1.23-7.93), and persistent bacteremia (aHR,1.74; 95%CI 1.05-2.89) significantly predicted poor outcomes in multivariable analysis. CONCLUSION: FUBC showing persistent bacteremia predicted poor outcomes among neutropenic patients with carbapenem-resistant gram-negative bloodstream infections (CRGNBSI) and should be routinely reported.

Hypervirulent Klebsiella pneumoniae infection presenting as endocarditis and liver abscess.

Hypervirulent Klebsiella pneumoniae infection, reported commonly from South-east Asia, is predominantly community-acquired and affects young healthy adults. Although abscesses of liver, brain and muscles, endophthalmitis or osteomyelitis have been reported, Infective endocarditis is a rare manifestation. This report illustrates a patient with uncontrolled diabetes mellitus who presented with clinical features of liver abscess with an incidental finding of infective endocarditis. Hypervirulent K. pneumoniae, which was isolated from blood culture of the patient carried the plasmid borne key virulence markers-rmpA and rmpA2 with enterobactin (entB), type 3 fimbriae (mrkD) and was of K1 type and ST3321, an uncommon clone of Hypervirulent K. pneumoniae. Transthoracic Echocardiography showed multiple mobile vegetations attached to mitral valve and posterior wall of left ventricle. With appropriate antibiotics blood cultures turned sterile, liver abscess and cardiac vegetations reduced in size. Mitral Valve replacement surgery was proposed. He declined treatment and succumbed to the infection subsequently.

Hybrid Plasmids Encoding Antimicrobial Resistance and Virulence Traits Among Hypervirulent Klebsiella pneumoniae ST2096 in India.

Background: Hypervirulent variants of Klebsiella pneumoniae (HvKp) were typically associated with a broadly antimicrobial susceptible clone of sequence type (ST) 23 at the time of its emergence. Concerningly, HvKp is now also emerging within multidrug-resistant (MDR) clones, including ST11, ST15, and ST147. MDR-HvKp either carry both the virulence and resistance plasmids or carry a large hybrid plasmid coding for both virulence and resistance determinants. Here, we aimed to genetically characterize a collection of MDR-HvKp ST2096 isolates haboring hybrid plasmids carrying both antimicrobial resistance (AMR) and virulence genes. Methods: Nine K. pneumoniae ST2096 isolated over 1 year from the blood sample of hospitalized patients in southern India that were MDR and suspected to be HvKp were selected. All nine isolates were subjected to short-read whole-genome sequencing; a subset (n = 4) was additionally subjected to long-read sequencing to obtain complete genomes for characterization. Mucoviscosity assay was also performed for phenotypic assessment. Results: Among the nine isolates, seven were carbapenem-resistant, two of which carried blaNDM-5 on an IncFII plasmid and five carried blaOXA-232 on a ColKP3 plasmid. The organisms were confirmed as HvKp, with characteristic virulence genes (rmpA2, iutA, and iucABCD) carried on a large (~320 kbp) IncFIB-IncHI1B co-integrate. This hybrid plasmid also carried the aadA2, armA, blaOXA-1, msrE, mphE, sul1, and dfrA14 AMR genes in addition to the heavy-metal resistance genes. The hybrid plasmid showed about 60% similarity to the IncHI1B virulence plasmid of K. pneumoniae SGH10 and ~70% sequence identity with the first identified IncHI1B pNDM-MAR plasmid. Notably, the hybrid plasmid carried its type IV-A3 CRISPR-Cas system which harbored spacer regions against traL of IncF plasmids, thereby preventing their acquisition. Conclusion: The convergence of virulence and AMR is clinically concerning in K. pneumoniae. Our data highlight the role of hybrid plasmids carrying both AMR and virulence genes in K. pneumoniae ST2096, suggesting that MDR-HvKp is not confined to selected clones; we highlight the continued emergence of such genotypes across the species. The convergence is occurring globally amidst several clones and is of great concern to public health.

Aerobactin Seems To Be a Promising Marker Compared With Unstable RmpA2 for the Identification of Hypervirulent Carbapenem-Resistant Klebsiella pneumoniae: In Silico and In Vitro Evidence.

Background: The incidence of hypervirulent (hv) carbapenem-resistant (CR) Klebsiella pneumoniae (Kp) is increasing globally among various clones and is also responsible for nosocomial infections. The CR-hvKp is formed by the uptake of a virulence plasmid by endemic high-risk clones or by the uptake of plasmids carrying antimicrobial resistance genes by the virulent clones. Here, we describe CR-hvKp from India belonging to high-risk clones that have acquired a virulence plasmid and are phenotypically unidentified due to lack of hypermucoviscosity. Methods: Twenty-seven CRKp isolates were identified to possess rmpA2 by whole-genome sequencing; and resistance and virulence determinants were characterized. By in silico protein modeling (and validation), protein backbone stability analysis, and coarse dynamics study, the fitness of RmpA, RmpA2, and aerobactin-associated proteins-IucA and IutA, were determined to establish a reliable marker for clinical identification of CR-hvKp. Results: The CR-hvKp belonged to multidrug-resistant (MDR) high-risk clones such as CG11, CG43, ST15, and ST231 and carried OXA-232 as the predominant carbapenemase followed by NDM. The virulence plasmid belonged to IncHI1B replicon type and carried frameshifted and truncated rmpA and rmpA2. This resulted in a lack of hypermucoviscous phenotype. However, functional aerobactin was expressed in all high-risk clones. In silico analysis portrayed that IucA and IutA were more stable than classical RmpA. Furthermore, IucA and IutA had lower conformational fluctuations in the functional domains than the non-functional RmpA2, which increases the fitness cost of the latter for its maintenance and expression among CR-hvKp. Hence, RmpA and RmpA2 are likely to be lost among CR-hvKp owing to the increased fitness cost while coding for essential antimicrobial resistance and virulence factors. Conclusion: Increasing incidence of convergence of AMR and virulence is observed among K. pneumoniae globally, which warrants the need for reliable markers for identifying CR-hvKp. The presence of non-functional RmpA2 among high-risk clones highlights the significance of molecular identification of CR-hvKp. The negative string test due to non-functional RmpA2 among CR-hvKp isolates challenges phenotypic screening and faster identification of this pathotype. This can potentially be counteracted by projecting aerobactin as a stable, constitutively expressed, and functional marker for rapidly evolving CR-hvKp.

Distinctive Mobile Genetic Elements Observed in the Clonal Expansion of Carbapenem-Resistant Klebsiella pneumoniae in India.

Background: Klebsiella pneumoniae (Kp), a common multidrug-resistant pathogen, causes a wide spectrum of nosocomial infections with high rates of morbidity and mortality. The emergence of pan drug-resistant international high-risk clones such as ST258, ST14, ST15, ST147, and ST101 is a global concern. This study was performed to investigate the carbapenemases, the plasmid profile, and the clonal relationship among Indian K. pneumoniae. Materials and Methods: A total of 290 K. pneumoniae isolates from seven centers in India were characterized to determine sequence types (STs) and carbapenemases. A subset of isolates was subjected to whole genome sequencing and hybrid genome assembly to obtain the complete genome. Plasmids carrying carbapenemases were characterized to determine the dissemination of carbapenem-resistant (CR) K. pneumoniae. Results: From this study, 75 different STs were observed with ST231 being predominant. About 79% of the analyzed isolates were CR with 59% (n = 136) producing OXA48-like carbapenemases. While ST231 was the predominant clone among the OXA48-like producers; NDM producers and NDM+OXA48-like producers were mostly associated with ST14. Interestingly, 61% (n = 138) of the total CR K. pneumoniae were colistin resistant, belonging to 22 different STs. Plasmid profiling shows that blaOXA48-like was exclusively carried by ColKP3, whereas blaNDM was associated with IncFII-like plasmids. Conclusion: The highly mosaic genome of K. pneumoniae coupled with the diverse ecological niches in India makes it a hotspot for antimicrobial resistance, leading to increased morbidity and mortality. Extensive molecular surveillance of the clonal spread of K. pneumoniae could help in understanding AMR dynamics and thus rework therapeutic management.

Emergence of Multidrug Resistant Hypervirulent ST23 Klebsiella pneumoniae: Multidrug Resistant Plasmid Acquisition Drives Evolution.

Background: In recent years, the emergence of multidrug resistant hypervirulent K. pneumoniae (MDR hvKp) isolates poses severe therapeutic challenge to global public health. The present study used the complete genome sequence of two MDR hvKp isolates belonging to ST23 to characterize the phylogenetic background and plasmid diversity. Methods: Two hvKp isolates from patients with bacteremia were sequenced using Ion Torrent PGM and Oxford Nanopore MinION platforms and assembled by hybrid genome assembly approach. Comparative genomics approaches were used to investigate the population structure, evolution, virulence, and antimicrobial resistance of MDR hvKp strains. Results: The study isolates exhibited typical features of hvKp phenotypes associated with ST23. The convergence of multidrug resistance and hypervirulence were attributed by the presence of multiple plasmids including a 216 kb virulence plasmid and MDR plasmids belonging to IncA/C2, IncFIB, IncX3, and ColKP3 groups. The insertion of catA1 gene into virulence plasmid was observed along with genetic factors such as aerobactin, salmochelin, and rmpA2 that confer hvKp's hypervirulent phenotype. The core genome single nucleotide polymorphism (SNP) phylogenetic analyses of the isolates showed the evolution of ST23 hvKp was predominantly driven by ICEKp acquisitions. Conclusion: To the best of our knowledge, this is the first report of MDR hvKp isolates of ST23 with insertion of catA1 gene into the virulence plasmid which presents the possibility of hotspot integration sites on the plasmids to aid acquisition of AMR genes. ST23 is no longer confined to susceptible strains of hvKp. Our findings emphasize the need for more studies on recombinant events, plasmid transmission dynamics and evolutionary process involving hvKp.

Identification of plasmids by PCR based replicon typing in bacteremic Klebsiella pneumoniae.

BACKGROUND: Klebsiella pneumoniae is a notorious pathogen with plasmid mediated resistance to all classes of antibiotics. It is important to determine the plasmid profile coding for resistance genes. Plasmid profile varies among geographical regions and tracking the types helps in determining the MDR and XDR K. pneumoniae spread especially in hospital setting. Aim of the present study was to determine the plasmid profile and types among bacteraemic K. pneumoniae. MATERIALS AND METHODS: Ninety consecutive K. pneumoniae collected over a period of three months from blood cultures were characterised by PCR for plasmid profile. Inc plasmid types were determined by PCR based replicon typing (PBRT) and carbapenemases were determined by multiplex PCR. For a subset of isolates hybrid assemblies were developed by sequencing with Ion Torrent and MinIon. RESULTS: Overall, PBRT showed 29% of isolates carried four plasmids including IncHI1B, IncFIA, IncFII(K) and IncR. The most common type of plasmid was IncHI1B (93%) followed by IncFIIK (89%) and IncR (82%). IncFIA was predominant among carbapenem resistant isolates. Almost all plasmids identified in K. pneumoniae were AMR plasmids, except two isolates which had virulence plasmids. IncX3 plasmid observed in this study was previously reported to be self-disseminating. Furthermore, the hybrid genome sequencing revealed complete structural arrangements of plasmids, which would be missed in short-read sequencing. NDM and OXA48-like were co-produced in 59% of the carbapenem resistant isolates. BlaOXA-232 was present on ColKP3; aac(6')-lb3 and rmtF on IncFIB. CONCLUSION: Diverse plasmid profile among the successive K. pneumoniae isolates indicates the transfer of resistance genes through different types of plasmids. IncHI1B, IncFIA, IncFIIK and IncR were the prevalent plasmid types. Hybrid assembly revealed blaOXA-232 was present on ColKP3 unlike global reports of IncL/M. Hybrid assemblies provide better plasmid structure that long and short read assemblies. There was no significant association of ß-lactamases with specific Inc groups in this study.

Current strategy for local- to global-level molecular epidemiological characterisation of global antimicrobial resistance surveillance system pathogens.

The prime goal of molecular epidemiology is to identify the origin and evolution of pathogens, which can potentially influence the public health worldwide. Traditional methods provide limited information which is not sufficient for outbreak investigation and studying transmission dynamics. The recent advancement of next-generation sequencing had a major impact on molecular epidemiological studies. Currently, whole-genome sequencing (WGS) has become the gold standard typing method, especially for clinically significant pathogens. Here, we aimed to describe the application of appropriate molecular typing methods for global antimicrobial resistance surveillance system pathogens based on the level of discrimination and epidemiological settings. This shows that sequence-based methods such as multi-locus sequence typing (MLST) are widely used due to cost-effectiveness and database accessibility. However, WGS is the only method of choice for studying Escherichia coli and Shigella spp. WGS is shown to have higher discrimination than other methods in typing Klebsiella pneumoniae, Acinetobacter baumannii and Salmonella spp. due to its changing accessory genome content. For Gram positives such as Streptococcus pneumoniae, WGS would be preferable to understand the evolution of the strains. Similarly, for Staphylococcus aureus, combination of MLST, staphylococcal protein A or SCCmec typing along with WGS could be the choice for epidemiological typing of hospital- and community-acquired strains. This review highlights that combinations of different typing methods should be used to get complete information since no one standalone method is sufficient to study the varying genome diversity.

Bad bug, no test: Tigecycline susceptibility testing challenges and way forward.

Tigecycline is a reserve antibiotic increasingly used for the treatment of multidrug-resistant bacteria, especially Klebsiella pneumoniae and Acinetobacter baumannii. At present, there are concerns regarding the testing and interpretation of tigecycline susceptibility to bugs such as K. pneumoniae and A. baumannii, which limit clinicians in appropriate usage. Use of appropriate method for testing such as broth microdilution is essential. In addition, tigecycline susceptibility testing is a challenge due to inconsistent results from various antimicrobial susceptibility testing automated platforms. There is a great need to define a suitable methodology along with interpretive criteria, especially for K. pneumoniae and A. baumannii. The European Committee on Antimicrobial Susceptibility Testing (EUCAST) and the Food and Drug Administration (FDA) breakpoints show wide variation and are defined for different set of organisms. Non-species-related pharmacokinetic/pharmacodynamic (PK/PD) breakpoints defined by the EUCAST can be used for organisms such as K. pneumoniae and A. baumannii.

Rapidly disseminating blaOXA-232 carrying Klebsiella pneumoniae belonging to ST231 in India: multiple and varied mobile genetic elements.

BACKGROUND: Recently, in India, there has been a shift from NDM to OXA48-like carbapenemases. OXA-181 and OXA-232 are the frequently produced variants of OXA48-like carbapenemases. OXA48-like carbapenemases are also known to be carried on transposons such as Tn1999, Tn1999.2 and it is also associated with IS1R carried on Tn1999. In India, there are no previous reports studying the association of mobile genetic elements (MGEs) with OXA48-like carbapenemases. The present study was aimed at determining the genetic backbone of OXA48-like carbapenemases to determine the role of MGEs in its transfer and to investigate the Inc plasmid type carrying blaOXA48-like. RESULTS: A total of 49 carbapenem resistant K. pneumoniae which included 25 isolates from South India and 24 isolates from North India, were included in the study. Whole genome sequencing using Ion Torrent PGM was performed to study the isolates. OXA-232 was present in 35 isolates (71%). In 19 isolates (39%), blaOXA48-like was associated with MGEs. Insertion sequences such as ISX4, IS1, IS3, ISKpn1, ISKpn26, ISKpn25, ISSpu2, ISKox1, IS4321R, ISEc36, and ISPa38; and transposons such as TnAs3 and Tn2, were present. Isolates from northern and southern India belonging to same sequence type (ST) had diverse genetic backbone for blaOXA48-like. ST14 isolates from north had IS5 and Tn3 families while from south they had IS1, IS5 and IS630 families. ST231 from north had IS5, IS6 and Tn3 families with blaOXA-232 while from south, IS1, IS3 and IS5 families were observed; with ISKpn26 being present among isolates from both the regions. blaOXA48-like was predominantly found on ColKP3 plasmid. ST231 was the predominant ST in 22 isolates (45%). CONCLUSION: OXA-232 is the predominant variant of OXA48-like carbapenemase with ST231 being the commonest ST of OXA48-like carbapenemase producing K. pneumoniae in India. Diverse MGEs have been associated with both blaOXA-232 and blaOXA-181 which contribute to their spread. The MGEs in the present study are different from those reported earlier. There is no clonal expansion of blaOXA48-like producing K. pneumoniae since diverse STs were observed. Monitoring the genetic backbone of OXA48-like carbapenemase is essential to better understand the transmission dynamics of XDR K. pneumoniae.

Molecular characterization of colistin-resistant Klebsiella pneumoniae & its clonal relationship among Indian isolates.

Background & objectives: Klebsiella pneumoniae (KP), a common cause of invasive infections, is often extensively drug resistant in India. At present, studies on resistance mechanism and clonal relationship of KP from India are limited. The present study was undertaken to determine the resistance mechanism and clonal relationship of colistin-resistant isolates obtained from various specimens. Carbapenemases were also determined since the isolates were carbapenem resistant. Methods: Sixty five isolates from blood, exudates and respiratory specimens collected between 2016 and 2017 were studied. Colistin minimum inhibitory concentration (MIC) was performed by broth-micro dilution method. Multiplex PCR was carried out to determine carbapenemases. Targeted sequencing was performed to determine mutations in mgrB, phoP, phoQ and multilocus sequence typing was performed to determine the prevalent clones. Results: Colistin MIC ranged from 4 to 256 µg/ml. SHV, TEM and CTX-M were co-produced in 60 per cent and OXA48-like in 71 per cent. Thirteen isolates had mutations in mgrB. Mutations included a premature stop codon at 21st amino acid, the presence of insertion sequences such as IS903, IS Kpn 14 and ISK pn 26; and elongation of mgrB. Novel mutations were also observed among phoP and phoQ genes. Colistin resistance due to mcr genes was absent. Fifteen clonal types were seen with ST231, ST14 and ST2096 being predominant. Interpretation & conclusions: This study revealed the changing trend of carbapenem resistance mechanism predominantly to OXA48-like from NDM. Known mgrB mutations and novel mutations in phoP and phoQ were detected. There was no plasmid-mediated colistin resistance. ST14 and ST231 were international clones associated with carbapenem resistance. Colistin-resistant KP was of diverse clones with predominantly ST231, ST14 and ST2096.

Emergence of ST147 Klebsiella pneumoniae carrying blaNDM-7 on IncA/C2 with ompK35 and ompK36 mutations in India.

India is known to be endemic to NDM carbapenemases. However, NDM-7 among Klebsiella pneumoniae has not been described from India. Apart from carbapenemases, ompK35 and ompK36 also contribute to carbapenem resistance in K. pneumoniae. This study describes molecular mechanisms of antimicrobial resistance in an isolate from bacteraemia investigated through whole genome sequencing. blaNDM-7 was found on IncA/C2 plasmid which also carried sul-1, aadA2, rmtC, blaCMY-6 and ARR-2. ompK35 had mutations and changes from 39th amino acid. ompK36 was truncated to 248 amino acids. The isolate belonged to ST147. The patient was a known case systemic lupus erythematosus (SLE) and blood culture grew carbapenem resistant K. pneumoniae. Meropenem, colistin and tiecoplanin were administered and the patient was discharged on improvement. Emergence of new resistance variants and porin mutations among clones such as ST147 which has been prevalent has potential for rapid spread and thus challenges infection control.

In-vitro activity of tigecycline and comparator agents against common pathogens: Indian experience.

INTRODUCTION: Tigecycline Evaluation and Surveillance Trail (TEST) study is an on-going global surveillance. The study was performed to determine the susceptibility of common pathogens to tigecycline and comparator antibiotics by broth microdilution (BMD) at two tertiary care centres in India from 2015 to 2017. METHODOLOGY: Total of 989 isolates collected from various clinical specimens between January 2015 and September 2017 from two centres in India were included. BMD was performed to determine the minimum inhibitory concentration (MIC) for tigecycline and comparator antibiotics. RESULTS: Among Gram-negative bacteria, susceptibility to tigecycline was lowest among Klebsiella spp. being 84% while others such as E. coli, Enterobacter spp., Serratia spp. and H. influenzae showed susceptibility of 98%, 95%, 98% and 100% respectively. Overall, 99 isolates among Enterobacteriaceae (E. coli, Klebsiella spp. and Enterobacter spp.) were ESBL producers, susceptible to tigecycline. Among the 101 meropenem resistant Enterobacteriaceae, 85 were susceptible to tigecycline (84%). Among the Gram-positive bacteria, S. aureus and Enterococcus spp. were 99% and 98% susceptible to tigecycline respectively. Among 68 MRSA isolates in the study, 66 (97%) were susceptible to tigecycline. Seven vancomycin resistant E. faecalis were isolated and all were susceptible to tigecycline. CONCLUSION: Tigecycline has retained activity over both Gram-positive and Gram-negative organisms with MIC values comparable to global reports. About 98% of the MDR Gram-positive and Gram-negative bacteria in the study are susceptible to tigecycline. With increased incidence of extensively drug resistant organisms, tigecycline is a potential reserve drug.

First Report of Whole-Genome Sequence of Colistin-Resistant Klebsiella quasipneumoniae subsp. similipneumoniae Producing KPC-9 in India.

Aim: Klebsiella pneumoniae carbapenemase (KPC) is a class A carbapenemase endemic in the United States, China, South America, and Europe but is rarely reported from India. A single report of KPC-9 from K. pneumoniae in Israel has been published. K. pneumoniae has been classified into three phylogenetic groups: group 1 consists of K. pneumoniae and its subspecies, group 2 consists of Klebsiella quasipneumoniae and its subspecies, and group 3 consists of Klebsiella variicola. This is the first report of whole-genome sequencing of colistin-resistant K. quasipneumoniae subsp. similipneumoniae harboring blaKPC-9 gene. Results: The isolate was obtained from the culture of a respiratory catheter tip from a 41-year-old woman with traumatic brain injury. Whole-genome sequencing showed the presence of blaOKP-B-3 gene and hence it was identified as K. quasipneumoniae subsp. similipneumoniae. The isolate was resistant to all antimicrobials except tigecycline. Colistin resistance was chromosomally mediated; mcr-1 to mcr-5 genes and their variants were not identified. The isolate belonged to the novel clonal type ST2957. Conclusion: The isolation of KPC-9 from India, a nonendemic region, and in an isolate of K. quasipneumoniae highlights the importance of accurate identification of Klebsiella species and determination of mechanism of resistance. The novel sequence type obtained indicates evolution of the organism and acquisition of plasmid-mediated resistance. The occurrence of KPC in India is a potential public health threat.

Detection of chromosomal and plasmid-mediated mechanisms of colistin resistance in Escherichia coli and Klebsiella pneumoniae from Indian food samples.

OBJECTIVES: Numerous previous publications on the detection of bacterial isolates harbouring the mcr-1 gene from animals and humans strongly suggest an underlying route of transmission of colistin resistance via the food chain. The aim of this study was to investigate the presence of colistin-resistant (Col-R) bacteria in Indian food samples and to identify the underlying mechanisms conferring colistin resistance. METHODS: Raw food material, including poultry meat, mutton meat, fish, fruit and vegetables, collected from food outlets in Chennai, India, were processed to identify Col-R bacteria using eosin methylene blue agar supplemented with colistin. Colistin minimum inhibitory concentrations (MICs) were determined by the broth microdilution method. PCR for the mcr-1 and mcr-3 genes was performed on Col-R Escherichia coli and Klebsiella pneumoniae isolates. Mutations in the mgrB gene were analysed in K. pneumoniae isolates. One representative mcr-1-positive E. coli was subjected to whole-genome sequencing. RESULTS: Of 110 food samples tested, 51 (46.4%) were positive for non-intrinsic Col-R Gram-negative bacteria. Three E. coli isolates were found to harbour mcr-1, whereas none were positive for mcr-3. Ten K. pneumoniae isolates had alterations in mgrB, with mutations in four and insertional inactivation in six. CONCLUSION: The presence of Col-R bacteria and the mcr-1 gene in raw food samples further complicates the antimicrobial resistance scenario in India. To the best of our knowledge, this is the first report in the global literature on mgrB mutation and its insertional inactivation conferring Col-R in K. pneumoniae from food samples.

KPC-2 producing ST101 Klebsiella pneumoniae from bloodstream infection in India.

This study characterizes KPC-2 producing Klebsiella pneumoniae belonging to ST101. Whole genome sequencing using the Ion Torrent PGM platform with 400 bp chemistry was performed. blaKPC-2 was found on an IncFIIK plasmid associated with ISKpn6 and ISKpn7 without Tn4401. This is the first report of KPC-2 K. pneumoniae from bacteremia in India. The isolate also coded for other resistance genes such as aadA1, aadA2, armA, aac(3)-Ild, aac(6')-Ild for aminoglycoside; blaSHV-11, blaTEM-1B, blaOXA-9, for ß-lactams and aac(6')-Ild, oqxA, oqxB, qnrB1 for fluoroquinolones. It belonged to the K17 capsular type. India is endemic to New Delhi metallo-ß-lactamase and OXA48-like carbapenemases and K. pneumoniae carbapenemase (KPC) is seldom reported. With high rates of carbapenem resistance, emergence of KPC in India will challenge patient management. The isolate was susceptible to colistin. The patient had a fatal outcome.

Molecular characterisation for clonality and transmission dynamics of an outbreak of Klebsiella pneumoniae amongst neonates in a tertiary care centre in South India.

PURPOSE:: Sepsis is a significant cause of morbidity and mortality amongst neonates. Klebsiella pneumoniae is a common cause of nosocomial outbreaks causing bacteraemia and having potential of acquiring plasmids enhancing antimicrobial resistance. In the present study, we investigate K. pneumoniae outbreak causing bacteraemia amongst neonates over a span of 2 months. Isolates were characterised for antimicrobial resistance, virulence, molecular typing for clonality and plasmid typing for transmission dynamics, and patient outcome was investigated. METHODS: Thirteen isolates of K. pneumoniae were obtained during October-November 2016. Antimicrobial susceptibility testing was performed, and multiplex polymerase chain reaction (PCR) for ß-lactamases and PCR for ompK35 and ompK36 were performed. To study hypervirulence, string test and PCR for rmpA and rmpA2 were performed. Multilocus sequence typing and Inc plasmid typing were carried out to study transmission dynamics. RESULTS: Amongst 13 isolates, all isolates harboured blaSHVand blaTEM; 12 isolates carried blaCTX-M-1. ompK35 was present in all, but ompK36 was absent in 12 isolates. Ten isolates belonged to ST48, 6 amongst which contained IncFII (K) plasmid. One isolate each belonged to ST29, ST111 and ST2647 (novel clone). None of the isolates was hypervirulent. CONCLUSION: Extended-spectrum ß-lactamase K. pneumoniae is commonly seen in Indian hospitals and main mechanisms being production of SHV, TEM and CTX-M enzymes as seen in the present study. Outer membrane porins contribute significantly to antimicrobial resistance. Emergence of new clones such as ST2647 implies continuous evolution of the organism and also potential for rapid genetic recombination leading to multidrug resistance. Outbreaks amongst neonates lead to fatal outcome, and stringent hospital infection control is necessary.

Whole genome analysis of hypervirulent Klebsiella pneumoniae isolates from community and hospital acquired bloodstream infection.

BACKGROUND: Hypervirulent K. pneumoniae (hvKp) causes severe community acquired infections, predominantly in Asia. Though initially isolated from liver abscesses, they are now prevalent among invasive infections such as bacteraemia. There have been no studies reported till date on the prevalence and characterisation of hvKp in India. The objective of this study is to characterise the hypervirulent strains isolated from bacteraemic patients for determination of various virulence genes and resistance genes and also to investigate the difference between healthcare associated and community acquired hvKp with respect to clinical profile, antibiogram, clinical outcome and molecular epidemiology. RESULTS: Seven isolates that were susceptible to all of the first and second line antimicrobials and phenotypically identified by positive string test were included in the study. They were then confirmed genotypically by presence of rmpA and rmpA2 by PCR. Among the study isolates, four were from patients with healthcare associated infections; none were fatal. All patients with community acquired infection possessed chronic liver disease with fatal outcome. Genes encoding for siderophores such as aerobactin, enterobactin, yersiniabactin, allantoin metabolism and iron uptake were identified by whole genome sequencing. Five isolates belonged to K1 capsular type including one K. quasipneumoniae. None belonged to K2 capsular type. Four isolates belonged to the international clone ST23 among which three were health-care associated and possessed increased virulence genes. Two novel sequence types were identified in the study; K. pneumoniae belonging to ST2319 and K. quasipneumoniae belonging to ST2320. Seventh isolate belonged to ST420. CONCLUSION: This is the first report on whole genome analysis of hypervirulent K. pneumoniae from India. The novel sequence types described in this study indicate that these strains are evolving and hvKp is now spread across various clonal types. Studies to monitor the prevalence of hvKp is needed since there is a potential for the community acquired isolates to develop multidrug resistance in hospital environment and may pose a major challenge for clinical management.