Indian Journal of Medical Microbiology IAMM  | About us |  Subscription |  e-Alerts  | Feedback |  Login   
  Print this page Email this page   Small font sizeDefault font sizeIncrease font size
 Home | Ahead of Print | Current Issue | Archives | Search | Instructions  
Users Online: 1960 Official Publication of Indian Association of Medical Microbiologists 
  Search
 
  
 ~  Similar in PUBMED
 ~  Search Pubmed for
 ~  Search in Google Scholar for
 ~  Article in PDF (537 KB)
 ~  Citation Manager
 ~  Access Statistics
 ~  Reader Comments
 ~  Email Alert *
 ~  Add to My List *
* Registration required (free)  

 
 ~  References
 ~  Article Figures
 ~  Article Tables

 Article Access Statistics
    Viewed97    
    Printed0    
    Emailed0    
    PDF Downloaded18    
    Comments [Add]    

Recommend this journal

 


 
  Table of Contents  
CORRESPONDENCE
Year : 2019  |  Volume : 37  |  Issue : 4  |  Page : 593-594
 

Emerging atypical non-lactose-fermenting phenotypic variants of klebsiella pneumoniae and escherichia coli in admitted patients of a trauma centre


1 Department of Microbiology, JPNATC, All India Institute of Medical Sciences, New Delhi, India
2 Department of Laboratory Medicine, JPNATC, All India Institute of Medical Sciences, New Delhi, India

Date of Submission14-Feb-2020
Date of Acceptance26-Mar-2020
Date of Web Publication18-May-2020

Correspondence Address:
Purva Mathur
Department of Laboratory Medicine, JPNATC, All India Institute of Medical Sciences, New Delhi
India
Login to access the Email id

Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ijmm.IJMM_20_61

Rights and Permissions



How to cite this article:
Bajpai V, Mathur P. Emerging atypical non-lactose-fermenting phenotypic variants of klebsiella pneumoniae and escherichia coli in admitted patients of a trauma centre. Indian J Med Microbiol 2019;37:593-4

How to cite this URL:
Bajpai V, Mathur P. Emerging atypical non-lactose-fermenting phenotypic variants of klebsiella pneumoniae and escherichia coli in admitted patients of a trauma centre. Indian J Med Microbiol [serial online] 2019 [cited 2020 Jun 2];37:593-4. Available from: http://www.ijmm.org/text.asp?2019/37/4/593/284533


Dear Editor,

Klebsiella pneumoniae and Escherichia coli are facultative anaerobic, Gram-negative bacilli that ferment lactose and produce pink-pigmented colonies in MacConkey agar media.[1] Up to 10% of E. coli isolates have historically been reported to be slow or non-lactose-fermenting variants that are termed as 'inactive', but non-lactose-fermenting K. pneumoniae strains are not known.[2] Phenotypically, atypical colony morphological and unusual biochemical characteristics of these non-lactose fermenting are a challenge for clinical microbiologists to identify and suggest the therapeutic options to clinicians. This communication reports a sudden occurrence of 'atypical' phenotype of K. pneumoniae and E. coli at our centre.

The findings were observed at the Department of Microbiology of Jai-Prakash Narayan Apex Trauma Centre, All India Institute of Medical Science, New Delhi. All consecutive isolates of non-lactose, slow-fermenting (having atypical morphology) E. coli and K. pneumoniae from various clinical samples were studied for confirmatory identification and antimicrobial sensitivity by VITEK 2 (BioMeriux, Germany) and MALDI-TOF (BioMeriux, Germany). Patient's demographic details and clinical details were followed up.

We found three nonlactose-fermenting isolates (two K. pneumoniae and one E. coli) from 2 pus samples and one urine sample, respectively. Unlike the usual phenotypic morphology of K. pneumoniae (large shiny, mucoid and dark pink in colour), our three isolates of K. pneumoniae were small-to-medium size in appearance, shiny, non-lactose fermenting on MacConkey agar media [Figure 1]. On comparison of biochemical properties (VITEK-2), it was found that these atypical strains were negative for urease production, beta-galactosidase production, beta-xylosidase production, proline A utilisation and tyrosine A utilisation and positive for malate and lactate assimilation test in contrast to the ATCC control K. pneumoniae strain. On comparison of biochemical reactions of E. coli (VITEK-2), it was found that the atypical E. coli was negative for lactate alkalisation, alpha-galactosidase production and tyrosine A utilisation test. [Table 1] shows the comparison of various biochemical properties of various isolates of K. pneumoniae and E. coli. Our findings also highlighted that one of the atypical K. pneumoniae isolates was a pan-drug-resistant strain including colistin.
Figure 1: Phenotypic morphology of isolates in MaConkey agar

Click here to view
Table 1: Comparison of biochemical reactions in various isolates

Click here to view


This change in phenotypic expression in K. pneumoniae and E. coli may be due to morphological plasticity, which is a survival strategy adopted in response to environmental stresses, such as antimicrobial exposure and other mechanical constraints.[3] This phenomenon is well known in uropathogenic E. coli strains but is highly uncommon in K. pneumoniae strains.[4] These observations challenge our traditional views of microbiological identification and testing and thus could drive the development of new and improved approaches to control multidrug-resistant bacteria in clinical settings.

Our study highlights that bacterial colony characteristics must be observed meticulously. To avoid misidentification of atypical variants of K. pneumoniae and E. coli, automated identification system is useful in clinical laboratory settings. For confirm identification, the atypical strains must be subjected to whole-genome sequencing, which will also help us identifying the genetic mechanism behind their morphological plasticity and phenotypic heterogenecity.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
 ~ References Top

1.
Guentzel MN. Escherichia, Klebsiella, Enterobacter, Serratia, Citrobacter, and Proteus. In: Baron S, editor. Medical Microbiology. 4th edition. Galveston (TX): University of Texas Medical Branch at Galveston; 1996. Chapter 26.  Back to cited text no. 1
    
2.
Drawz SM, Bonomo RA. Three decades of beta-lactamase inhibitors. Clin Microbiol Rev 2010;23:160-201.  Back to cited text no. 2
    
3.
Justice S, Hunstad D, Cegelski L, Hultgren SJ. Morphological plasticity as a bacterial survival strategy. Nat Rev Microbiol 2008;6:162-8.  Back to cited text no. 3
    
4.
Sarowska J, Futoma-Koloch B, Jama-Kmiecik A, Frej-Madrzak M, Ksiazczyk M, Bugla-Ploskonska G, et al. Virulence factors, prevalence and potential transmission of extraintestinal pathogenic Escherichia coli isolated from different sources: Recent reports. Gut Pathog 2019;11:10.  Back to cited text no. 4
    


    Figures

  [Figure 1]
 
 
    Tables

  [Table 1]



 

Top
Print this article  Email this article
 

    

2004 - Indian Journal of Medical Microbiology
Published by Wolters Kluwer - Medknow

Online since April 2001, new site since 1st August '04