|Year : 2010 | Volume
| Issue : 3 | Page : 217-220
Prevalence and risk factors for colonisation with extended spectrum β-lactamase producing enterobacteriacae vis-à-vis usage of antimicrobials
JB Sarma1, GU Ahmed2
1 Consultant Microbiologist and Infection Control Doctor, Northumbria Healthcare NHS Foundation Trust, Rake Lane, NE288NH, England, United Kingdom
2 Department of Biotechnology, Guwahati University, Jalukbari, Guwahati, Assam-781 014, India
|Date of Submission||28-Jul-2009|
|Date of Acceptance||13-Jan-2010|
|Date of Web Publication||17-Jul-2010|
J B Sarma
Consultant Microbiologist and Infection Control Doctor, Northumbria Healthcare NHS Foundation Trust, Rake Lane, NE288NH, England
Source of Support: North East Clinical Excellence Foundation, Conflict of Interest: None
Purpose: A point prevalence study was carried out in a teaching hospital in Assam to determine the prevalence, sensitivity profile and risk factors for acquisition of extended spectrum β-lactamase (ESBL) producing enterobacteriacae vis-ΰ-vis amount and pattern of antibiotic use. Materials and Methods: ESBL was detected by double disc synergy method. Defined daily dose and bed-days were calculated. Result: Colonisation rate of ESBL producing enterobacteriacae ranged from 14% (n=73) in medicine to the highest 41% (n=29) in orthopaedic with an intermediate 23% (n=80) in surgery. Presence of ESBL was found to be strongly associated with resistance to specific classes of antimicrobials. Exposure to cefotaxime and gentamicin, and surgery were risk factors for acquiring ESBL producing enterobacteriacae. Non-ESBL producing community isolates were found to be considerably more sensitive to different antibiotics with no resistance detected to trimethoprim, co-trimoxazole, ciprofloxacin and aminoglycosides. Conclusion: The study confirms the role of certain 'high risk' antimicrobials in acquisition of ESBL producing Enterobacteriaceae and shows that periodic cohort studies could be an effective strategy in surveillance of antimicrobial resistance in hospitals of resource poor countries to inform antibiotic policy and treatment guidelines.
Keywords: Antibiotic consumption, ESBL producing enterobacteriacae, infection control
|How to cite this article:|
Sarma J B, Ahmed G U. Prevalence and risk factors for colonisation with extended spectrum β-lactamase producing enterobacteriacae vis-à-vis usage of antimicrobials. Indian J Med Microbiol 2010;28:217-20
|How to cite this URL:|
Sarma J B, Ahmed G U. Prevalence and risk factors for colonisation with extended spectrum β-lactamase producing enterobacteriacae vis-à-vis usage of antimicrobials. Indian J Med Microbiol [serial online] 2010 [cited 2019 Sep 23];28:217-20. Available from: http://www.ijmm.org/text.asp?2010/28/3/217/66476
| ~ Introduction|| |
The introduction of ceftazidime and aztreonam shortly after cefotaxime has accelerated the evolution of (ESBLs) in hospitals worldwide roughly at the same time and is now a major problem.  Acquired resistance to β-lactams is mainly mediated by ESBLs that confer resistance to all β-lactams except carbapenems and cephamycins, and are usually plasmid encoded which frequently carry genes encoding resistance to other drug classes. The total number of ESBLs characterised now exceeds 200 ( www.lahey.org/Studies ). There has been a recent dramatic increase of CTX-M enzymes over TEM and SHV variants.  CTX-M-type ESBLs exhibit powerful activity against cefotaxime and ceftriaxone but generally not against ceftazidime, however, several CTX-M variants with enhanced ceftazidimase activity have been detected. CTX-M-15, a variant of the CTX-M-3, resistant to both cefotaxime and ceftazidime, was detected in isolates from patients hospitalized in a New Delhi hospital in 2000.  Although ESBLs still constitute the first cause of resistance to β-lactams, alarmingly metallo-β-lactamases and Klebsiella pneumoniae Carbapenemases (KPC), and CMY enzymes conferring resistance to carbapenems and cephamycins, respectively have more recently emerged and are often associated with ESBLs. 
This study describes the colonisation rate of ESBL producing enterobacteriacae and their antibiogram vis-à-vis usage of antimicrobials in a hospital with no or little infection control interventions which was typical of most Indian hospitals at the time of the study.
| ~ Materials and Methods|| |
A point prevalence study was conducted at a teaching hospital in Assam. Three surgical, one orthopaedic and four medical units involving 182 male patients were included in a single day point prevalence study in August 2001. Baseline demographic data, diagnoses, procedures performed and antimicrobials prescribed with their duration were recorded from the patient's medical record.
Dry swabs from nose and throat, and any open wounds (not under dressing) were collected and plated on to MacConkey agar and incubated overnight. The suspect typical colonies of enterobacteriacae on the MacConkey plate were slopped in nutrient agar and shipped in triple containment packaging with labelling and marking meeting United Nation's requirements for transportation of "Biological Substance, Category B" to the microbiology laboratory at the Royal Victoria Infirmary, Newcastle upon Tyne, UK. No other regulatory permission was sought as the only pertinent regulation, Government of India's Guidelines for Exchange of Human Biological Material of 19th November, 1997 for Biomedical Research Purposes which defines human material with potential for use in biomedical research, does not include infectious agents.
Presumptive isolates of enterobacteriacae were identified using the LOGIC identification system (a set of conventional biochemical tests); , a few isolates that did not give acceptable LOGIC profile were identified by API 20E® systems (Biomιrieux, Marcy l'Etoile, France).
Isolates were tested against a range of antimicrobials using British Society of Antimicrobial Chemotherapy (BSAC) Standardized Disc Sensitivity Method  using Oxoid® (Oxoid Ltd, England) discs to generate a profile for interpretive reading. 
Detection of extended spectrum ί-lactamases (ESBL) in E. coli and Klebsiella were carried out using (I) Double-Disc Synergy Test (DDST), (II) Etest ESBL strips (AB Biodisk, Solna, Sweden; Cambridge Diagnostic Services, Cambridge, UK) and (III) Combined disc method; results were concordant by all the three methods.  tection of ESBL in Enterobacter cloacae and Enterobacter aerogenes was carried out using modified DDST.  Inducible chromosomal Amp C ί-lactamase was detected using cefotaxime 30 μg and cefoxitin 30 μg discs applied 25 mm apart - production was inferred by the blunting of the cefotaxime zone adjacent to the cefoxitin disc. Oxoid® (Oxoid Ltd, Cambridge, CB5 8BZ, UK) discs were used for DDST and combined disc methods.
Consumption of antimicrobials was calculated in Defined Daily Doses (DDD)/100 bed-days  using ABC Calc  as defined by the WHO Centre for Drug Statistics Methodology. A case was defined as a patient colonised with ESBL producing enterobacteriaceae. Equal numbers of controls (patients not colonised) matched for the duration of hospital stay were selected randomly using SPSS (version 10) from the cohort. The case-control study studied the following risk factors for acquisition of ESBL producing enterobacteriaceae (1) exposure to third generation cephalosporins, aminoglycosides and fluoroquinolones, (2) undergoing surgery and (3) the duration of hospitals stay. Age was not considered as the cohort was relatively young (mean age 34 in orthopaedic/surgery and 38 years in medicine) with no serious co-morbidities.
| ~ Results|| |
Consumption of antimicrobials
The overall consumption antimicrobials for systemic use were 92.6, 59.9 and 53.3 DDD/100 bed days in the surgical, orthopaedic and medical units, respectively. Consumption of cephalosporins and aminoglycosides were similar across the specialities (22-29 and 8-12 DDD/100 bed-days across the specialties) but fluoroquinolone consumption was disproportionately higher in surgery, 41 as opposed to only 7-8 DDD/100 bed-days in orthopaedic and medicine. The third generation cephalosporins, fluoroquinolone and aminoglycosides constituted the bulk of the total consumption.
Colonisation of ESBL producing enterobacteriacae
65 isolates belonging E. coli (n=17), K. pneumoniae (n=30), K. oxytoca (n=2), K. ornithinolytica (n=1), C. freundii (n=1), E. aerugenes (n=1), E. cloacae (n=4), M. morganii (n=1), P. mirabilis (n=5) and P. vulgaris (n=3) were identified as ESBL producers from 40 patients. Patients colonised with ESBL producing enterobacteriacae ranged from 14% (n=10) in medicine to 41% (n=12) in orthopaedics with an intermediate 23% (n=18) in surgery.
Profile of ESBL producing enterobacteriacae
All these isolates were resistant to ciprofloxacin, gentamicin, tobramycin and netilmicin (P < 0.001) in addition to amoxicillin, cefuroxime, cefotaxime, ceftazidime and aztreonam. Resistance to piperacillin was 92%. A proportion (52%) of these isolates appeared sensitive amoxicillin + clavulanic acid and piperacillin + tazobactam. Resistance to others was as follows: amikacin (18%), co-trimoxazole (~50%) and chloramphenicol (~50%). All isolates were sensitive to meropenem.
Profile of non-ESBL producing enterobacteriacae
Non-ESBL isolates from patients with ≤ 48h and ≥ 48h of hospital-stay were analysed separately to make a distinction between community and nosocomial isolates. No resistance was detected to second and third generation cephalosporins in any non-ESBL isolates.
In isolates (n=19) from patients with ≥ 48h of hospital stay, resistance was detected to multiple classes: amoxicillin (73%), co-amoxiclav (42%), cefalexin (32%), chloramphenicol (32%), co-trimoxazole (11%), trimethoprim (21%), ciprofloxacin (5%), gentamicin (5%), netilmicin (53%) and tobramycin (11%). Isolates (n=13) from patients with ≤ 48h of hospital-stay also demonstrated equally high resistance to amoxicillin (77%) but at lower level to co-amoxiclav (15%), cefalexin (17%), chloramphenicol (25%) and netilmicin (17%). No resistance was detected to trimethoprim, co-trimoxazole, ciprofloxacin, gentamicin, amikacin, and tobramycin in these community isolates.
Mantel-Haenszel odd ratio was calculated with 95% confidence interval with an associated P value for risk factors studied. Neither the duration of hospital stay (P 0.336) nor the exposure to fluoroquinolones (P 0.606) was a risk factor. However, aminoglycosides was very strongly associated with acquiring ESBL producing enterobacteriacae (P 0.007) followed by cephalosporins (P 0.025). Having a surgery during the stay was another significant risk factor (P 0.022).
| ~ Discussion|| |
Although K. pneumoniae and E. coli dominated, ESBL was detected in virtually every species of Enterobacteriaceae in this study. Patients at high risk for developing colonisation or infection with ESBL-producing organisms are often seriously ill patients with prolonged hospital stays and in whom invasive medical devices are present for a prolonged duration.  Our study has demonstrated that young patients with no serious co-morbidities in general wads are also at risk of colonization if exposed to 'high risk' antimicrobials. Several studies have found a relationship between third-generation cephalosporin use and acquisition of an ESBL-producing strain. ,,, Use of a variety of other antibiotic classes has been found to be associated with subsequent infections due to ESBL-producing enterobacteriaceae including fluoroquinolone , and aminoglycosides. , This study confirms exposure to third generation cephalosporins and aminoglycosides as strong risk factors. In contrast, the duration of hospital stay (P 0.336) was very weakly associated as risk factors in our current study. The study demonstrated that even in an environment where multi-resistant bacterial pathogens were endemic and there was no or little infection control interventions, a significant proportion of patients not exposed to high risk antimicrobials remained free from colonisation demonstrating the importance of commensals in protecting against nosocomial pathogens. Moreover, the exposure to fluoroquinolone (P 0.606) was not found to be a risk factor, which was surprising given that ESBL producing isolates was consistently resistant to ciprofloxacin. Tobramycin and netilmicin were not in use in the hospital despite observed consistent resistance suggesting the role of R-plasmids and associated linkage selection. Surgery as a risk factor is probably a marker of exposure to the 'high risk' antimicrobial as surgical patients received prolonged course of antibiotics both as prophylaxis and therapy.
In contrast, non-ESBL producing isolates, particularly, the community ones are sensitive to most including 'older' and inexpensive antimicrobials. Four ESBL producers and one Amp C derepressed mutant (inferred using interpretive reading of resistance phenotype ) were isolated from patients with ≤ 48h of hospital-stay. However, two of these ESBL producing isolates were from two patients who had been exposed to gentamicin and cefotaxime, respectively since admission, therefore, probably, hospital acquired reflecting early colonisation. The remaining two ESBL producers and one Amp C derepressed mutant could be community acquired but in absence of data about recent hospitalisation and antimicrobial exposure one could not be certain.
Although isolates from nose and throat were clearly colonising flora, the same could not be said for isolates recovered from the wounds, a proportion of which probably was responsible for wound infections. However, none of the antimicrobials found in use was effective against ESBL producing enterobacteriacae; so contribution of the antibiotic therapy was in fact nil even in patients who recovered from nosocomial infection potentially caused by ESBL producing bacteria. Routine use of broad-spectrum and 'high risk' antimicrobials such as third generation cephalosporins, fluoroquinolones and aminoglycosides in surgical patients should be avoided where ESBL is endemic. S. aureus is the main pathogen of surgical sites infections which should be treated with specific anti-staphylococcal antibiotics.
This study underlines the role for of local periodic studies in defined patient cohorts for a finite period to determine the local epidemiology of resistance, associated risk factors and most cost effective antimicrobial regimen for specific infections in a setting where routine diagnostic microbiology is either not available or not cost effective. 
| ~ References|| |
|1.||Medeiros AA. Evolution and dissemination of β-lactamases accelerated by generations of β-lactam antibiotics. Clin Infect Dis 1997;24:S19-45. |
|2.||Bonnet R. Growing group of extended-spectrum beta-lactamases: the CTX-M enzymes. Antimicrob Agents Chemother 2004;48:1-14. |
|3.||Karim A, Poirel L, Nagarajan S, Nordmann P. Plasmid-mediated extended-spectrum ί-lactamase (CTX-M-3 like) from India and gene association with insertion sequence ISEcp1. FEMS Microbiology 2001;201:237-41. |
|4.||Paterson DL, Bonomo RA. Extended-Spectrum β-Lactamases: a Clinical Update. Clin Microbiol Rev 2005;18:657-86. |
|5.||Perry JD, Ford M, Hjersing N, Gould FK. Rapid conventional scheme for biochemical identification of antibiotic resistance Enterobacteriacea isolates from urine. J Clin Pathol 1988;41:1010-2. |
|6.||Pattyn SR, Sion JP, Verhoeven J. Evaluation of the LOGIC system for the Rapid Identification of Members of the Family Enterobacteriacea in the Clinical Microbiology laboratory. J Clin Microbiol 1990;28:1449-50. |
|7.||BSAC Standardized Disc Susceptibility Testing Method. http://www.bsac.org.uk/susceptibility_testing/bsac_standardized_disc_susceptibility_method.cfm |
|8.||Livermore DM, Winstanley TG, Shannon KP. Interpretive reading: recognising the unusual and interfering resistance mechanism from resistance phenotypes. J Antimicrob Chemother 2001;48:87-102. |
|9.||Livermore DM, Brown DF. Detection of β-lactamase-mediated resistance. J Antimicrob Chemother 2001;48:59-64. |
|10.||Tzelepi E, Giakkoupi P, Sofianou D, Loukova V, Kemeroglou A, Tsakris A. Detection of Extended-Spectrum β-Lactamases in clinical isolates of enterobacter cloacae and enterobacter aerogenes. J Clin Microbiol 2000;38:542-6. |
|11.||ATC classification index with DDD. WHO Collaborating Centre for Drug Statistics Methodology, 2002. |
|12.||Monnet DL. ABC Calc- Antibiotic consumption calculator (Version1.8). Statens Serum Institute, 2002. |
|13.||Paterson DL, Bonomo RA. Extended-Spectrum β-Lactamases: a clinical update. Clin Microbiol Rev 2005;18:657-86. |
|14.||Asensio A, Oliver A, Gonzαlez-Diego P, Baquero F, Pιrez-Dνaz JC, Ros P, et al. Outbreak of a multiresistant Klebsiella pneumoniae strain in an intensive care unit: antibiotic use as risk factor for colonization and infection. Clin Infect Dis 2000;30:55-60. |
|15.||Du B, Long Y, Liu H, Chen D, Liu D, Xu Y, et al. Extended-spectrum beta-lactamase-producing Escherichia coli and Klebsiella pneumoniae bloodstream infection: risk factors and clinical outcome. Intensive Care Med 2002;28:1718-23. |
|16.||Eveillard M, Schmit JL, EB F. Antimicrobial use prior to the acquisition of multiresistant bacteria. Infect Control Hosp Epidemiol 2002;23:155-8. |
|17.||De Champs C, Rouby D, Guelon D, Sirot J, Sirot D, Beytout D, et al. A case-control study of an outbreak of infections caused by Klebsiella pneumoniae strains producing CTX-1 (TEM-3) beta-lactamase. J Hosp Infect 1991;18:5-13. |
|18.||Lautenbach E, Patel JB, Bilker WB, Edelstein PH,Fishman NO. Extended-spectrum beta-lactamase-producing Escherichia coli and Klebsiella pneumoniae: risk factors for infection and impact of resistance on outcomes. Clin Infect Dis 2001;32:1162-71. |
|19.||Wiener J, Quinn JP, Bradford PA, Goering RV, Nathan C, Bush K, et al. Multiple antibiotic-resistant Klebsiella and Escherichia coli in nursing homes. JAMA 1999;281:517-23. |
|20.||Livermore DM, Winstanley TG, Shannon KP. Interpretive reading: recognising the unusual and interfering resistance mechanism from resistance phenotypes. J Antimicrob Chemother 2001;48:87-102. |
|21.||Archibald LK, Reller LB. Clinical microbiology in developing countries. Emerg Infect Dis 2001;7:302-5. |
|This article has been cited by|
||Co-infection of methicillin-resistantStaphylococcus epidermidis, methicillin-resistantStaphylococcus aureusand extended spectrum▀-lactamase producingEscherichia coliin bovine mastitis ľ three cases reported from India
| ||Samiran Bandyopadhyay,Indranil Samanta,Debaraj Bhattacharyya,Pramod Kumar Nanda,Debasish Kar,Jayanta Chowdhury,Premanshu Dandapat,Arun Kumar Das,Nayan Batul,Bimalendu Mondal,Tapan Kumar Dutta,Gunjan Das,Bikash Chandra Das,Syamal Naskar,Uttam Kumar Bandyopadhyay,Suresh Chandra Das,Subhasish Bandyopadhyay |
| ||Veterinary Quarterly. 2014; : 1 |
|[Pubmed] | [DOI]|
||Genotypic characteristics of multidrug-resistantEscherichia coliisolates associated with urinary tract infections
| ||Xiaoli Cao,Zhifeng Zhang,Han Shen,Mingzhe Ning,Junhao Chen,Hongxia Wei,Kui Zhang |
| ||APMIS. 2014; : n/a |
|[Pubmed] | [DOI]|
||Molecular epidemiology of extended spectrum ▀-lactamase-producing Escherichia coli and Klebsiella pneumoniae in a tertiary care hospital
| ||N Kammili,N Cherukuri,S Palvai,GP Pazhni,T Ramamurthy,JV Rao,PR Anuradha |
| ||Indian Journal of Medical Microbiology. 2014; 32(2): 205 |
|[Pubmed] | [DOI]|
||The new medical challenge: why NDM-1? Why Indian?
| ||Timothy R Walsh,Mark A Toleman |
| ||Expert Review of Anti-infective Therapy. 2011; 9(2): 137 |
|[Pubmed] | [DOI]|
||Extended-spectrum beta-lactamase orthopedic wound infections in Nigeria
| ||Idowu, O.J., Onipede, A.O., Orimolade, A.E., Akinyoola, L.A., Babalola, G.O. |
| || Journal of Global Infectious Diseases. 2011; 3(3): 211-215 |
||The new medical challenge: Why NDM-1? Why Indian?
| || Walsh, T.R., Toleman, M.A. |
| ||Expert Review of Anti-Infective Therapy. 2011; 9(2): 137-141 |
||Multidrug-resistant Enterobacteriaceae including metallo-β-lactamase producers are predominant pathogens of healthcare-associated infections in an Indian teaching hospital
| ||Sarma, J., Bhattacharya, P., Kalita, D., Rajbangshi, M. |
| ||Indian Journal of Medical Microbiology. 2011; 29(1): 22-27 |