Resistance of some Gram Negative Enteric Bacilli Isolated from Lower Respiratory Tract Infections to β-lactam Antibiotics

One hundred and four isolates of gram negative enteric bacilli were isolated from (700) sputum specimens taken from lower respiratory tract infections with isolation percentage of (14.8%). The bacterial isolates belonged to the species: Pseudomonas aeruginosa, Klebsiella pneumoniae, Escherichia coli, Enterobacter aerogenes, Enterobacter cloacae, Serratia marcescens, Proteus mirabilis, with variable isolation percentages. The isolates showed an obvious resistance to different -lactam antibiotics including third generation cephalosporins, where the resistance percentages to Cefixime, Cefotaxime, Ceftazidime reached (52.9%), (51.9%), (42.3%) respectively, they also showed resistance to Cefoxitin (31.7%), while Cefepime, Meropenem, Imipenem had a high activity against the isolates, as the resistance rates were reduced to reach (8.7%), (1.9%), (1.0%) respectively. Ps.aeruginosa isolates were the most resistant species to -lactams, followed by K.pneumoniae isolates, while Pr. mirabilis isolates were the most susceptible ones.