Outbreak of bloodstream infection with extended-spectrum ß-lactamase-producing Klebsiella pneumoniae at a Teaching Hospital

Introduction: Klebsiella pneumoniae ( K. pneumoniae ) is an important hospital-acquired pathogen causing severe infections in neonatal units. Several outbreaks of infection caused by multi-drug-resistant K. pneumoniae isolates have been widely reported among neonates. The aim is to investigate an outbreak of blood stream infection caused by Extended-Spectrum s-Lactamases (ESBL) producing K.pneumoniae in a Neonatal Intensive Care Unit (NICU) at Teaching Hospital Kandy, Sri Lanka. Materials and Methods: Blood culture samples were collected from the neonates on admission to the NICU and 2 to 3 days later on clinical suspicion of blood stream infection. The blood culture samples were processed according to the standard methods and the antibiotic susceptibility tests were carried out as per Clinical Laboratory Standards Institute (CLSI) guidelines. Results: Of the 140 blood cultures 36 were identified as Extended-Spectrum s-Lactamases (ESBL) producing K.pneumoniae. All the isolates were susceptible to ciprofloxacin, amikacin, netilmicin, imipenem and meropenem. Twenty eight of the 36 patients responded to treatment with a combination of amikacin and meropenem. Conclusion: ESBL producing K.pneumoniae was responsible for this outbreak at the NICU. Knowing the susceptibility patterns of clinical isolates will allow the rational use of antibiotics, which is important in the treatment of infections with multi-drugresistant bacteria. J Nepal Paediatr Soc 2014;34(3):230-232 DOI: http://dx.doi.org/10.3126/jnps.v34i3.10459


Introduction
K lebsiella pneumoniae is an important hospital-acquired pathogen with the poten al of causing severe infec ons in neonatal units 1,2 .For neonates in high-dependency units, hospital acquired bloodstream infec ons are an important cause of morbidity and mortality 3 .
Several outbreaks of infec on caused by K. pneumoniae isolates that are simultaneously resistant to broad-spectrum cephalosporins and aminoglycosides have been widely reported 1 .Some of these mul drug-resistant isolates produce extendedspectrum ß-lactamases (ESBLs) that are able to hydrolyze extended-spectrum cephalosporins (eg.ce riaxone, cefotaxime, and ce azidime), aztreonam, and related oxyimino-B-lactams.(4)   The objec ve of this study was to inves gate an outbreak of blood stream infec on caused by extendedspectrum ß-lactamases (ESBL) producing K.pneumoniae in a neonatal intensive care unit (NICU) at Teaching Hospital Kandy, Sri Lanka during the period December 2009 to January 2010.

Materials and Methods
This study was carried out at the NICU at the Teaching Hospital Kandy, Sri Lanka, which experienced an outbreak of blood stream infec ons during the period 2 nd December 2009 to 17 th January 2010.
Blood culture samples were taken from all the neonates who were admi ed to the NICU during this period.The blood cultures were taken on admission to the NICU and 2 to 3 days later on clinical suspicion of blood stream infec on.The clinical diagnosis or suspicion of neonatal sep caemia was made by the paediatric unit responsible for the care of the pa ent.
Blood culture samples were collected asep cally and bo les showing evidence of growth a er overnight incuba on at 37 o C were promptly sub-cultured into MacConkey, Blood and chocolate agar media and incubated in appropriate temperature, atmospheres according to established methods.The clinical isolates were iden fi ed by Gram's staining, colony characteris cs and the fi ndings were confi rmed by the API 20E system.The an bio c suscep bility tests and the detec on of ESBL were carried out as per Clinical Laboratory Standards Ins tute (CLSI) guidelines.

Results
During this period 145 neonates were admi ed to the NICU at Teaching Hospital Kandy, and a total of 140 blood cultures were collected from them.All the ini al blood culture samples collected from the neonates on admission to the NICU were nega ve.Seventy six (54.28%) of the 140 blood culture samples which were collected 2 to 3 days a er admission to the NICU became posi ve for bacterial growths, while 64 (45.71%) yielded no growth.Of the 76 posi ve cultures 48 (63.15%) were pure growths.Of the 48 pure cultures 36 (75%) isolates were iden fi ed as ESBL producing K.pneumoniae and 12 (25%) isolates were iden fi ed as coagulase nega ve staphylococcal species.
All the isolates of K pneumoniae shared the in vitro suscep bility to gentamicin, amikacin, ne lmicin, imipenem and meropenem.All the clinical isolates were resistant to cefotaxime, ce azidime and ce riaxone.
Twenty eight of the 36 pa ents responded to treatment with a combina on of amikacin and meropenem.Eight of the 36 pa ents died of sepsis in spite of appropriate an bio cs.

Discussion
The Neonatal Intensive Care Unit (NICU) at the Teaching Hospital Kandy, Sri Lanka experienced an outbreak of 36 cases of K.pneumoniae blood stream infec ons during the period 2 nd December 2009 to 17 th January 2010.
The most signifi cant fi nding of this study was that all the Klebsiella pneumoniae isolates were resistant to commonly used an bio cs and were extended spectrum ß-lactamase producers (ESBL).
The signifi cant morbidity and mortality arising from intra-hospital infec on with mul -drug-resistant strains of K.pneumoniae, as seen in this report, is reason for alarm.
The high incidence of ESBL producing K.pneumoniae sep caemia and the an bio c suscep bility pa ern, indicate that the infec on was most probably nosocomial in origin.
It appears that the lack of control of contamina on sources and hand hygiene has caused the dissemina on of the microorganisms among pa ents.However, there was no direct evidence of the source of contamina on or transmission of the mul drug-resistant strains, although it was possibly due to transitory hand contact through health care workers 5 .

Conclusion
Knowing the suscep bility and resistance pa erns in these types of clinical isolates will allow the implementa on of improved therapeu c measures and the ra onal use of an bio cs, which are indispensable tools in fi gh ng infec ous diseases caused by mul drug resistant bacteria.