Introduction: Klebsiella pneumoniae is a common cause of nosocomial
infections; however, there is limited information in Iran regarding nosocomial outbreaks
due to extended-spectrum β–lactamase (ESBL) producing K pneumoniae
strains, particularly using molecular methods. The present study focused on the molecular
mechanism of ESBL resistance and genetic relatedness in K. pneumoniae
isolates causing nosocomial infections in an Iranian referral hospital.
Material and Methods: This study evaluated the antimicrobial resistance and molecular
epidemiology of K. pneumoniae causing nosocomial infections in children
between October 2013 and March 2014. The ESBL detection was carried out for all
the isolates by the CLSI method and PCR was carried out for the detection of the
blaSHV, blaTEM, and blaCTX-M genes among ESBL-producing K. pneumonia. Molecular
typing of the K. pneumoniae was performed using random amplification of
polymorphic DNA-polymerase chain reaction (RAPD-PCR).
Results: A total of 30 isolates of K. pneumoniae were used for epidemiological
analysis. High rates of resistance to cefotaxime (n=29, 97%), cefazolin (n=29, 97%),
cefepime (n=25, 83%) and gentamicin (n=23, 77%) were observed. A total of 29
strains (97%) produced ESBLs. The frequency of blaSHV, blaCTX-M and blaTEM genes
among these isolates was 83% (n=25), 70% (n=21) and 57% (n=17), respectively.
Surprisingly 11 isolated (37%) carried blaSHV, blaCTX-M and blaTEM genes
simultaneously. Moreover, the concurrent presence of “blaSHV and blaCTX-M” and
“blaSHV and blaTEM” was seen in 8 (27%) and 4 (13%) isolates, respectively. RAPDPCR
analyses revealed that K. pneumoniae isolates belonged to 2 RAPD-PCR
types among which one cluster counted for 28 isolates.
Conclusion: To our knowledge, this is the first published report of a nosocomial
outbreak of ESBL-producing K. pneumoniae in children in Iran. Although the epidemiology
of nosocomial infections with ESBL-producing organisms has not yet
been explored in depth in Iran, our findings suggest that ESBL-producing organisms
are already an established public health threat in our country.