Introduction

Extended spectrum β- lactamase (ESBL) producing organisms, are now being recognized as one of the major threats to effective management of patients in medical institutions, especially in the less developed nations ₁ . Klebsiella pneumoniae, Escherichia coli and Klebsiella oxytoca have been reported by a number of workers to harbor ESBL enzyme ₂,₃ . ESBL producing organisms are inhibited by β- lactam - β-lactamase inhibitors but are not with extended spectrum – cephalosporins ₄ . ESBL are encoded by genes on plasmids which results in easy transfer of ESBL enzymes to other bacteria species ₅ . Originally, ESBL enzymes were derived from the widespread TEM and SHV β- lactamase family, however today, over 110 derivatives of TEM β- lactamase and more than 63 derivatives of SHV β-lactmases are known ₆ .

Detection of ESBL enzymes using routine laboratory susceptibility tests is often difficult and consequently, ESBL producing Klebsiella species and E. coli may falsely appear to be susceptible to newer cephalosporins ₇ . The National Committee for Clinical Laboratories Standards (NCCLS) recommends that Microbiology laboratories should report ESBL – isolates of E. coli and Klebsiella species as resistant to all penicillins and cephalosporins including cefepime and aztreonam irrespective of their individual in vitro test results ₈ .The present study was designed to determine the antibiotic susceptibility patterns of ESBL producing K. pneumoniae from different clinical specimen.

Material And Methods

Isolation of organisms

Sensitivity studies

Detection of ESBL production

Results

The result of the present study showed that out of the 105 Klebsiella pneumoniae isolates, 38 (36.2%) showed evidence of ESBL production (Table 1). Isolates from blood yielded the highest percentage ESBL producers (54.2%) while stool sample gave the least (26.3%). (Table 1).

The susceptibility studies revealed a clear difference in susceptibility patterns of organisms obtained from different specimens including urine, blood and stool. ESBL producing organisms isolated from urine were susceptible to nitrofurantoin, nalidixic, ceporex, augmentin, ciprofloxacin and amikacin while isolates from blood were susceptible to nitrofurantoin, gentamicin, augmentin, ciprofloxacin, septrin and amkacin. Further, organisms isolated from stool specimen were susceptible to nalidixic acid, augmentin, ceporex, ciprofloxacin, and amikacin. It was observed that ESBL organisms from all the specimens were generally resistant to ceftazidime, cefotaxime and ceftriaxone (Table 2).

Figure 1

Table 1: Percentage of ESBL producing isolates of from urine, blood and stool samples.

Figure 2

Table 2: Percentage Susceptibility patterns of ESBL positive organism from urine, stool and blood.

Discussion

The result of this investigation shows that organisms harboring ESBL enzymes are multi-drug resistant and thus, could pose serious treatment challenges. The presence of ESBL on plasmids makes it possible for them to be easily transferred from one organism to another. Some studies have shown that floroquinolones and aminoglycosides have antimicrobial activity against ESBL organisms than other non β- lactams drugs ₉,₁₀ . The overall result of the present study shows that while the prevalence of ESBL producing isolates in Abakaliki is currently not very high, it may escalate and cause a very serious public health problem, if not checked in good time. The constant use of third generation cephalosporins in the treatment of infections in Nigeria, is probably the reason for the current spread of ESBL organisms in our environment ₁₁ .

Information as regards ESBL are very uncommon in our environment and as a result, most clinicians probably don't know when to test for ESBL or any preventive measures to adopt that will help to control its spread. This level of ignorance could culminate to devastating consequences. While some studies have shown that the use of β?lactam β lactamase inhibitors such as amoxicillin-clavulanic acid and piperacillin – tazobactam in the treatment of ESBL infection is possible, others states that in vitro susceptibility testing does not predict a killing activity of β- lactam β?lactamase inhibitor ₄ . Also, Etrapenem antibiotic has been shown by some workers to have activity against ESBL from Klebsiella spp ₁₂ . It is vital to note, that some of these apparently efficacious drugs against ESBL producers are not readily available in Nigeria and where available, may be beyond the reach of the common man. The need to avert the further spread of this enzyme is thus emphasized.

It is interesting to note however, that the results of susceptibility studies also revealed that ESBL producing organisms were sensitive to the floroquinolones and the aminoglycosides than other non-beta lactam drugs. This probably indicates that they could be a drug of choice in treating infections caused by ESBL producing organisms, particularly Klebsiella pneumoniae, in our environment, at least at the present time.

In conclusion, the results of our work shows that ESBL producing Klebsiella pneumoniae isolated from different clinical specimens (blood, urine and stool) showed differences in their rate of antimicrobial susceptibility. Although the prevalence rates of ESBL in our study was not too high, it is hereby suggested that an antibiotic prescription formular should be develop in hospitals/clinics in Abakaliki, Nigeria, that will guide the use of third generation cephalosporins for therapeutic purposes.

Acknowledgement