Klebsiella pneumoniae is an important Gram-negative opportunistic bacterium and a frequent cause of nosocomial infections, accounting for up to 10% of all nosocomial infections.[16] Carbapenems are the β-lactam antibiotics of choice for the treatment of infections caused by MDR organisms especially the extended-spectrum beta-lactamase (ESBL)-producing bacteria such as Klebsiella pneumoniae, and these antibiotics are also considered the last resort for the management of life-threatening health-care-associated infections.[17] Unfortunately, rising bacterial resistance to carbapenems has been, and is well documented.[18] Previous studies have shown that Klebsiella pneumoniae strains of environmental origin are similar to those strains of clinical origin in terms of biochemical patterns, virulence, and pathogenicity; however, clinical Klebsiella pneumoniae have been observed to be significantly more resistant to antibiotics when compared with environmental Klebsiella pneumoniae.[19]
Out of the 534 sources sampled in this study, Klebsiella pneumoniae was isolated from 15 (2.8%) of the population. Similar but slightly lower values were obtained in a study conducted on environmental isolates of Klebsiella pneumoniae in an Egyptian hospital, where 4/100 (0.04%) of the study population was found to harbor Klebsiella pneumoniae.[20] In this study 142 organisms were isolated from the 534 samples, and out of these 15/142 (10.6%) were confirmed to be Klebsiella pneumoniae with 8/15 (53%) of these organisms observed to be producing carbapenemases. This finding corresponds with previously documented studies that found the prevalence of Klebsiella pneumoniae in nosocomial infections to be about 10%.[17] Mohammed et al., observed higher rates in Kano, Nigeria where 73/225 (32.4%) of the isolates were Klebsiella pneumoniae, with 6/73 (8.2%) of these Klebsiella pneumoniae producing carbapenemases.[9] High rates have also been recorded in the northern region of Brazil, where 25/25 (100%) of the Klebsiella pneumoniae isolates were confirmed as carbapenemase producers,[21] but much lower values were observed for clinical isolates of Klebsiella pneumoniae in a Chinese study 4/153 (2.6%).[22] The varying prevalence of carbapenemase production observed in these studies shows that several countries have different preferences for antibiotic prescription, and hence, varying selection pressures affecting antimicrobial resistance patterns. These varying observations were highlighted in a statement by Oduyebo et al., that carbapenemase production among the Enterobacteriaceae has been widely reported with prevalence rates ranging from between 2.8% and 53.6%.[8]
Of the 15 Klebsiella pneumoniae isolates, the most frequent site of isolation was in beds 6 (40%), followed by bedside cupboards 4 (26.7%), and then bedside Tables 2 (13.3%). This finding was similar to that observed in a study involving several ICU hospital environment sites in Cairo, Egypt, where the Klebsiella pneumoniae isolates were found mainly in beds, bedside tables, suction tubes and ventilator tubes.[11] Also worthy of note is that contrary to the Abdallah et al. study, no Klebsiella pneumoniae was isolated from the ICU in this study. This variation in the detection of the organisms from the ICUs of the different hospitals could be attributed to the maintenance of strict infection control measures in the ICU of NAUTH, Nnewi.
The antibiotic susceptibility patterns of the Klebsiella pneumoniae isolates revealed that the organisms had the highest resistance rates to Ampicillin (100%), Sulfamethoxazole-Trimethoprim (100%), Cefuroxime (100%), and Tetracycline (100%), but were most susceptible to the Carbapenem class of antibiotics (Imipenem, Meropenem and Ertapenem), in which Imipenem showed the most sensitivity (73.3%). Contrasting findings were observed in an Egyptian study which revealed 100% resistance to Meropenem.[11] The reduced rates of resistance to the carbapenems in this study could be attributed to the limited use of carbapenems due to its high cost of purchase in the country.
None of the 15 isolates of Klebsiella pneumoniae produced blaKPC. Although this was similar to findings observed in previous Nigerian studies which dealt with clinical isolates of Klebsiella pneumoniae,[8][23] contrasting observations were seen in Maiduguri, Nigeria (6.5%).[9] A significantly different finding was also observed in a brazillian study that revealed that 100% of the Klebsiella pneumoniae isolates carried the blaKPC gene.[21] The contrasting rates may be because of the long term high use of carbapenem antibiotics in Brazil, but still quite recent introduction of these drugs in Nigeria.
The Klebsiella pneumoniae isolates were phenotypically positive for carbapenemase production on Modified Hodge Test, but was negative for blaKPC genes on PCR. This could be because these isolates were harbouring carbapenemase genes other than those tested for in this study.