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CORRESPONDENCE
Year : 2014  |  Volume : 32  |  Issue : 2  |  Page : 205-207
 

Molecular epidemiology of extended spectrum β-lactamase-producing Escherichia coli and Klebsiella pneumoniae in a tertiary care hospital


1 Department of Microbiology, Gandhi Medical College, Secunderabad, Andhra Pradesh, India
2 Department of Pediatrics, Gandhi Medical College, Secunderabad, Andhra Pradesh, India
3 National Institute of Cholera and Enteric Diseases, Kolkata, West Bengal, India

Date of Submission10-Apr-2013
Date of Acceptance06-Nov-2013
Date of Web Publication2-Apr-2014

Correspondence Address:
N Kammili
Department of Microbiology, Gandhi Medical College, Secunderabad, Andhra Pradesh
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0255-0857.129856

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How to cite this article:
Kammili N, Cherukuri N, Palvai S, Pazhni G P, Ramamurthy T, Rao J V, Anuradha P R. Molecular epidemiology of extended spectrum β-lactamase-producing Escherichia coli and Klebsiella pneumoniae in a tertiary care hospital. Indian J Med Microbiol 2014;32:205-7

How to cite this URL:
Kammili N, Cherukuri N, Palvai S, Pazhni G P, Ramamurthy T, Rao J V, Anuradha P R. Molecular epidemiology of extended spectrum β-lactamase-producing Escherichia coli and Klebsiella pneumoniae in a tertiary care hospital. Indian J Med Microbiol [serial online] 2014 [cited 2019 Dec 9];32:205-7. Available from: http://www.ijmm.org/text.asp?2014/32/2/205/129856


Dear Editor,

Since their first report in 1983, extended spectrum β-lactamases (ESBLs) have spread worldwide and are most common in Escherichia coli and Klebsiella spp. Nosocomial infections are often due to micro-organisms endemic in the hospital. Besides the infected sites of patients, the gut of colonised or infected patients is the most important reservoir and physical contact is the most common mode of transmission. For every patient with clinically significant infection with an ESBL producer, at least one other patient exists in the same unit with gastrointestinal tract colonisation with ESBL producer. [1] Colonisation with ESBL-producing E. coli and Klebsiella spp. has been reported among hospitalised and out patients as well as healthy individuals in the community. [2] The foetal intestine is sterile. The gut of neonate born in a hospital gets colonised within 24-48 hours with microflora from mother and health care workers and could represent the microflora endemic in the hospital environment. Aim of the present study was to elucidate the molecular epidemiology of ESBL-producing E. coli and Klebsiella pneumoniae circulating in the hospital environment and community. Objective-to determine genetic relatedness of ESBL-producing E. coli and K. pneumoniae circulating-as gut colonisers of newborns and causative agents of infections in hospital and gut colonisers in community.

Single rectal/faecal specimens from 54 healthy neonates in post-natal ward (PNW) and 42 sick neonates in (NICU) who stayed in hospital for >48 hours, and 100 healthy individuals in community and 96 pus samples from wound infections were cultured on blood agar and Mac Conkey agar. E. coli and K. pneumoniae isolated were identified by standard biochemical tests. One-hundred and twenty-five isolates of E. coli were obtained comprising 112 colonisers (30 from newborns and 82 from healthy individuals in the community) and 13 clinical isolates. 89 isolates of K. pneumoniae were obtained comprising 60 colonizers (41 from new borns and 19 from healthy individuals in the community) and 29 clinical isolates. All the E. coli and K. pneumoniae isolates were tested for ESBL production by disc diffusion, disc potentiation and disc synergy test. [3],[4] ATCC E. coli 25922 and K. pneumoniae 700603 were used as controls.

Twenty-three (18.4%) E. coli isolates were ESBL positive which included 15 (13.4%) colonisers, 12 from newborns and three from healthy individuals and 8 (61.5%) clinical isolates. Thirty isolates (33.7%) of K. pneumoniae comprising 7 (17.7%) colonisers from newborns and 23 (79.3%) clinical isolates were ESBL positive.

In the hospital environment, both as a coloniser in the gut flora of newborns and a pathogen in clinical specimens, K. pneumoniae was more frequently isolated than E. coli (70 vs. 43 isolates). This could be attributed to the ability of K. pneumoniae to survive better in the hospital environment and persist on hands and other environmental surfaces longer than other Enterobacteriaceae facilitating cross-infection and dissemination in hospital. [1] 19.8% of newborns in the hospital and 3% healthy individuals in community were colonised with ESBL-producing enterobacteria. The difference was statistically significant (P < 0.05). In the present study none of healthy individuals were found to be colonised with ESBL-producing K. pneumoniae.

To study the clonal relationship of ESBL-producing E. coli and K. pneumoniae strains prevalent in the hospital, either colonising the newborns or isolated from clinical specimens from various wards in the hospital, molecular typing was done by pulsed field gel electrophoresis (PFGE) which was performed as described previously with small modification. [5] Fourteen strains of E. coli comprising six colonisers from new borns, three colonisers from community and five clinical isolates and 13 isolates of K. pneumoniae comprising six colonisers from new borns and 7 clinical isolates were subjected to PFGE. They were randomly selected. Dendrogam analysis revealed that 10/14 ESBL-P E. coli isolates were identical (>80% similarity) and included colonising strains from community and new borns and clinical isolates [Figure 1]. This indicates clonal dissemination of ESBL-positive E. coli in the community and hospital. In contrast ESBL-producing K. pneumoniae isolates were found to be polyclonal, each clone containing the colonisers and clinical isolates from hospital [Figure 2] suggestive of horizontal transmission of ESBL genes among different clones of K. pneumoniae in the hospital. Circulation of genetically related ESBL-producing E. coli strains in the community and hospital is an issue for concern and underscores the need for stringent control over antibiotic usage not only in the hospital but also in the community. Resistance pattern of gut flora of newborns in a hospital can be a simple and cost-effective indicator of antibiotic pressure in the hospital.
Figure 1: XbaI-PFGE profi les of E. coli isolates with dendrogram showing percentage similarity isolates 192A, 201, 196, 202, 73, 64 are from PNW; 40, 8, 272 from the community and 63, 36, 57, 7, 44 are from clinical source

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Figure 2: XbaI-PFGE profi les of K. pneumoniae isolates with dendrogram showing percentage similarity. Isolates 189A, 1814A are from NICU; 62, 96, 119 from PNW and 1738, 20, 1, 1844, 1707, 1712 from clinical source

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 ~ References Top

1.Paterson DL, Bonomo RA. Extended spectrum β-Lactamases: A clinical update. Clin Microbiol Rev 2005;18:657-86.  Back to cited text no. 1
    
2.Sarma JB, Ahmed GU. Prevalence and risk factors for colonization with extended spectrum beta-lactamase producing enterobacteriaceae vis-à-vis usage of antimicrobials Indian J Med Microbiol 2010;28:217-20.  Back to cited text no. 2
    
3.Clinical and Laboratory Standards Institute performance standards for antimicrobial susceptibility tests. Approved standard, 9 th ed. CLSI document M2-a9, Wayne, PA; 2006.  Back to cited text no. 3
    
4.Bradford PA. Extended-spectrum beta-lactamases in the 21 st century: Characterization, epidemiology, and detection of this important resistance threat. Clin Microbiol Rev 2001;14:933-51.  Back to cited text no. 4
[PUBMED]    
5.Yamasaki S, Nair GB, Bhattacharya SK, Yamamoto S, Kurazono H, Takeda Y. Cryptic appearance of a new clone of Vibrio cholerae O1 biotype El Tor in Calcutta, India. Microbiol Immunol 1997;41:1-6.  Back to cited text no. 5
    


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