Abstract:
Detection of extended spectrum β-lactamases (ESBLs) is a major challenge for the
clinical microbiology laboratory due to the variable affinity of these enzymes for
different substrates and inoculums effect. The present study was designed to detect
the ESBLs in Pseudomonas aeruginosaisolates from hospitalized patientsand to
evaluate their susceptibility pattern to antibiotics.
In this study, 350 specimens were collectedincludingwound swabs, eye swabs,
nasal swabs, ear swabs, urine and sputum from hospitalized patientsin Khartoum
State hospitals. The specimens were cultured on appropriate culture media.The
isolates were identified by their colonial morphology, Gram’s stain and
biochemicalidentification tests using the API 20E identification system. The
presence of ESBL enzymes weredetected by phenotypictechnique using double
disc synergy and combined disc methods. TEM, SHV, and CTX-M genes were
detected by polymerase chain reaction technique.
The results revealed that 65 clinical isolates of Ps. aeruginosa were recovered.
Only3(4.6%) of the isolateswere ESBL positivewhen examined by double disc
synergy test and combination disc test. Detectionof ESBLgenes by PCR showed
that only the gene CTX-M waspresent.
It is concluded that Ps. aeruginosa in general has ability to produce ESBLs as well
as members of Enterobacteriaciae, but in limited cases. Further studies utilizing
multiplex PCR for the detection TEM, SHV and CTX-M genes in ESBL
producing Ps. aeruginosa are highly recommended.
