Untreated wastewater is of considerable concern because of the risks it poses to the environment and human health, highlighting the need for effective treatment. The present study aimed to evaluate the presence of E. coli resistant to beta-lactam antibiotics and to determine the proportion of isolates producing beta-lactamase enzymes in the wastewater of selected Damascus University hospitals.

A total of 150 E. coli isolates were obtained from hospital wastewater and tested for susceptibility to a number of beta-lactam antibiotics. Resistance was 100% to first-generation cephalosporins, 86% to second-generation cephalosporins, and ranged from 78% to 100% for third-generation cephalosporins. Resistance to amoxicillin, a penicillin-class antibiotic, was 93%. Among the resistant isolates, 88% produced beta-lactamase enzymes belonging to Class A.

Following plasmid extraction using the boiling method and plasmid curing by increasing the incubation temperature to 42°C, with 8–10 successive subcultures, the results showed that blaCTX-type extended-spectrum beta-lactamase (ESBL) was the most frequently detected type in this study. This was determined using two sets of primers targeting two different genes, blaCTX and blaSHV.

In the present study, partial purification of CTX-type extended-spectrum beta-lactamase (ESBL) was successfully performed. Enzyme activity was determined by measuring the degradation of ceftriaxone at a wavelength of 290 nm using a UV spectrophotometer. Partial purification of the enzyme was carried out using a Sephadex G-100 column at a flow rate of 1 mL/min, with fractions 91–96 showing clear enzymatic activity.

Beta-lactamase production began during the third hour of the logarithmic growth phase at 37°C and reached its maximum level during the fifth hour. The results demonstrated that the partially purified enzyme could be used to degrade ceftriaxone in hospital wastewater.