Resistance to third-generation cephalosporins in Barbados

Resistance to third-generation, or extended-spectrum, cephalosporins caused by induction of class I beta-lactamases has been reported rarely from developing countries. Seven isolates of cephalosporin-resistant Gram-negative rods were recovered recently from urine, burns and ulcers in the Queen Elizabeth Hospital, Barbados. The isolates were identified as Acinetobacter calcoaceticus (2), Citrobacter freundii (1), Enterobacter cloacae (1), Morganella morganii (1), Providencia stuartii (1) and Proteus sp. (1). Induction of beta-lactamase by cefoxitin was demonstrated, and minimal inhibitory concentrations (MIC) were determined by agar dilution. beta-lactamases were demonstrated by isoelectric focusing; the presence of chromosomal beta-lactamases was confirmed in at least three of the resistant isolates. The only antibiotics which were uniformly active against these resistant strains were imipenem and ciprofloxacin. These data confirm the existence of resistance to the third-generation cephalosporins in Barbados, and emphasise the necessity for continuous surveillance of resistance patterns in the Caribbean region.