Extended-spectrum-beta-lactamases (ESBL) have been recovered from medical centres in South Africa since the late 1980’s but little is known about the various types of ESBLs present and their prevalence. Metallo-beta-lactamase is an emerging class of broad-spectrum beta-lactamases in non-fermenting Gram-negative bacteria worldwide. Klebsiella pneumoniae strains producing ESBLs and MBLs have been responsible for failure of therapy with extended-spectrum cephalosporins in healthcare settings. Multi-drug resistant K. pneumoniae is mostly transmitted from patient to patient, via hands of healthcare workers and contaminated care items. This study investigated the prevalence of ESBL and MBL antibiotic resistance genes in K. pneumoniae isolates from Pretoria Academic Hospital. A Multiplex Polymerase Chain Reaction (PCR) assay was used for the detection of four genes blaCTX-M, blaSHV, blaTEM and VIM genes in 97 K. pneumoniae isolates. Preliminary results indicated 90% (74/82) of K. pneumoniae isolates were positive for one or more of these ESBL genes. A total of 39% (32/82) of the isolates were positive for all three ESBL genes. In 4% (3/82) of the isolates blaSHV and blaTEM were detected and in another 4% (3/82) of the isolates blaCTX-M and blaSHV were detected, while blaCTX-M and blaTEM were detected in 20% (17/82) of the isolates. Only the blaSHV gene was detected in 14% (12/82) of the isolates, while only blaTEM was detected in 5% (4/82) and only blaCTX-M detected in 4% (3/82) of the K. pneumoniae isolates. The VIM gene was not detected in any of the isolates analysed in this study. The results obtained from this study emphasised the need to address the emergence and spread of ESBL-producing K. pneumoniae in clinical settings. Appropriate infection control measures should be implemented for all patients who are infected with ESBL-producing K. pneumoniae. The 90% prevalence of ESBL-producing K. pneumoniae isolates collected in this study reflects the overuse of the newer extended-spectrum cephalosporins. This high ESBL prevalence limits the therapeutic options of physicians treating patients, since carbapenems are the only beta-lactam drugs that are still active against ESBL-producing K. pneumoniae.
Poster presented at the University of Pretoria Health Sciences Faculty Day, August 2008, Pretoria, South Africa.