Prevalence and antimicrobial resistance among Gram-negative pathogens in Saudi Arabia.

Antimicrobial resistance among Gram-negative bacteria is a worldwide problem, including in the Kingdom of Saudi Arabia, with major concerns regarding Pseudomonas aeruginosa, Acinetobacter baumannii, and Enterobacteriaceae. Although over half of the isolates of P. aeruginosa remain susceptible to carbapenems, quinolones, and aminoglycosides in most reports from Saudi Arabia, resistance is on increase, with a worrying high prevalence of multidrug resistance. Ceftazidime, ciprofloxacin, and aminoglycosides remain active against A. baumannii isolates in some studies from the Kingdom, but recent data suggest increased resistance. Carbapenems are now the treatment of choice for Acinetobacter infections but their activity too is being eroded. Among Enterobacteriaceae, Escherichia coli, Klebsiella pneumoniae, and Enterobacter spp. are the most clinically relevant species. Rates of extended-spectrum beta-lactamase (ESBL) production by these species vary among studies but are generally high in Saudi Arabia, with many ESBL-producing isolates multiresistant to other agents, except carbapenems and nitrofurantoin. A similar pattern is seen for Klebsiella, although with more resistance to quinolones, aminoglycosides, and to nitrofurantoin than in E. coli. Enterobacter is commonly resistant to penicillins, monobactams, and cephalosporins but mostly susceptible to carbapenems. Carbapenemases are beginning to emerge in Enterobacteriaceae.