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.

Extremely High Mortality Rates in Patients with Carbapenem-resistant, Hypermucoviscous Klebsiella pneumoniae Blood Stream Infections.

BACKGROUND: Infections caused by carbapenem resistant K. pneumoniae are increasing and associated with high mortality rates. There are increasing reports of hypermucoviscous/ hypervirulent K. pneumoniae isolated from various sources. However, there is limited data on the prevalence of hypermucoviscous strains among carbapenem-resistant K. pneumoniae from invasive infections in India and its association with mortality. rmpA, rmpA2 and magA genes are associated with these hypervirulent strains. In this study, we investigate the prevalence of hypermucoviscous strains amongst carbapenem resistant K. pneumoniae isolated from blood culture. Association of mortality rate with meropenem minimum inhibitory concentration and hypermucoviscous strains are determined. METHODS: 86 non-repetitive carbapenem resistant K. pneumoniae isolated from bacteremia underwent E-test for meropenem minimum inhibitory concentration (MIC) determination and PCR for detection of carbapenamase genes. String test, PCR for rmpA, rmpA2 and magA were performed for characterisation of hypervirulent strains. Results: 31.3% of the 86 isolates displayed hypermucoviscous phenotype as indicated by a positive string test. Among the two genotypic markers, 7% were positive for rmpA2 and all were negative for rmpA and magA. 74.1% and 67.9% mortality were seen among string test positives and isolates meropenem MIC of ≥16µg/ml respectively (p 0.036 and 0.008 respectively). Isolates with both string positivity and meropenem MIC of ≥16µg/ml had a very high mortality rate of 84.2%. CONCLUSION: String test, aids prediction of disease severity, and is independently associated with increased mortality in invasive carbapenem resistant K.pneumoniae health care-acquired infections. High meropenem MIC is a significant risk factor for mortality. Combination of string positive carbapenem resistant hypermucoviscous K. pneumoniae resulted in mortality rate of 84.2%. It is important to monitor prevalence of carbapenem resistant hypermucoviscous/hypervirulent K. pneumoniae among invasive isolates especially in a setting with high resistance rates as combination of increased virulence and decreased susceptibility to antimicrobials results in worse outcomes.

Carbapenem resistant Klebsiella pneumoniae isolated from bloodstream infection: Indian experience.

Increased incidence of multidrug resistant (MDR) Gram negative infection has resulted in high rates of morbidity and mortality. Klebsiella pneumoniae is one of the commonest MDR pathogens causing bacteraemia with limited therapeutic options such as colistin and tigecycline. Present study focused on molecular characterisation of MDR K. pneumoniae from bloodstream infection and their clinical outcome. A total of 115 K. pneumoniae from January 2015 to September 2016 were included in the study which comprised of phenotypically identified ESBL and carbapenem resistant (CR) isolates. Multiplex PCR was performed for detection of resistance genes encoding ß-lactam resistance. This includes blaSHV, blaTEM, blaVEB, blaPER, blaCTX-M, blaDHA, blaCIT, blaFOX, blaACC, blaACT, blaNDM, blaOXA48-like, blaVIM and blaKPC. Co-expression of blaSHV, blaTEM and blaCTX-M was predominant with 64% (74/115) prevalence. CTX-M-1 was the variant produced by all the isolates producing CTX-M. AmpC was uncommon, seen in 5% of the isolates (6/115). Among the carbapenemases co-expression of blaNDM and blaOXA48-like was observed in 28% (32/115) and blaNDM in 19% (22/115) and blaOXA48-like in 13% (15/115). blaKPC was absent. Overall mortality was observed to be 57% (64/113) and mortality among CR K. pneumoniae (Kp) was 68% (50/73). The antibiotics that were administered for treatment of CRKp were colistin in 90% (66/73) and tigecycline in 7% (5/73) and in 99% combined with meropenem (72/73). Prevalence of community acquired and nosocomial infections were 5% (4/73) and 95% (69/73) respectively among CRKp. Minocycline and meropenem susceptibilities were comparable and hence minocycline can be a carbapenem sparing agent. The resistance to ß-lactam antibiotics is steadily increasing and are plasmid mediated, their containment in healthcare setting is a challenge.