Monitoring antibiotic resistance in ocular microorganisms: results from the Antibiotic Resistance Monitoring in Ocular micRorganisms (ARMOR) 2009 surveillance study.

PURPOSE: To determine the antibacterial susceptibility profile of bacterial pathogens from ocular infections against relevant aminoglycoside, ß-lactam, cephalosporin, chloramphenicol, fluoroquinolone, glycopeptide, lincosamide, and macrolide antibacterial agents. DESIGN: Laboratory investigation. METHODS: Isolates from patients with bacterial eye infections were collected prospectively by 34 institutions across the United States and were submitted to a central laboratory for inclusion in the Antibiotic Resistance Monitoring in Ocular micRorganisms (ARMOR) study. Minimum inhibitory concentrations were determined by microbroth dilution for 200 Staphylococcus aureus (S. aureus), 144 coagulase-negative staphylococci, 75 Streptococcus pneumoniae (S. pneumoniae), 73 Haemophilus influenzae (H. influenzae), and 100 Pseudomonas aeruginosa (P. aeruginosa) isolates. RESULTS: A large proportion of S. aureus and coagulase-negative staphylococci isolates were resistant to oxacillin/methicillin, azithromycin, or fluoroquinolones; 46.5% of S. aureus, 58.3% of coagulase-negative staphylococci, 9.0% of P. aeruginosa, and 9.3% of pneumococcal isolates were nonsusceptible to 2 or more antibacterial drug classes. Only 2.7% of H. influenzae isolates were nonsusceptible to 1 of the agents tested. Methicillin-resistant staphylococci were statistically more likely (all P < .0038) also to be resistant to fluoroquinolones, aminoglycosides, and macrolides. CONCLUSIONS: Resistance to 1 or more antibiotics is prevalent among ocular bacterial pathogens. Current resistance trends should be considered before initiating empiric treatment of common eye infections.

In vitro activity of doripenem, a carbapenem for the treatment of challenging infections caused by gram-negative bacteria, against recent clinical isolates from the United States.

Doripenem, a 1beta-methylcarbapenem, is a broad-spectrum antibiotic approved for the treatment of complicated urinary tract and complicated intra-abdominal infections. An indication for hospital-acquired pneumonia including ventilator-associated pneumonia is pending. The current study examined the activity of doripenem against recent clinical isolates for the purposes of its ongoing clinical development and future longitudinal analysis. Doripenem and comparators were tested against 12,581 U.S. clinical isolates collected between 2005 and 2006 including isolates of Staphylococcus aureus, coagulase-negative staphylococci, Streptococcus pneumoniae, Enterobacteriaceae, Pseudomonas aeruginosa, and Acinetobacter spp. MICs (microg/ml) were established by broth microdilution. By MIC(90), doripenem was comparable to imipenem and meropenem in activity against S. aureus (methicillin susceptible, 0.06; resistant, 8) and S. pneumoniae (penicillin susceptible, < or =0.015; resistant, 1). Against ceftazidime-susceptible Enterobacteriaceae, the MIC(90) of doripenem (0.12) was comparable to that of meropenem (0.12) and superior to that of imipenem (2), though susceptibility of isolates exceeded 99% for all evaluated carbapenems. The activity of doripenem was not notably altered against ceftazidime-nonsusceptible or extended-spectrum beta-lactamase screen-positive Enterobacteriaceae. Doripenem was the most potent carbapenem tested against P. aeruginosa (MIC(90)/% susceptibility [%S]: ceftazidime susceptible = 2/92%S, nonsusceptible = 16/61%S; imipenem susceptible = 1/98.5%S, nonsusceptible = 8/56%S). Against imipenem-susceptible Acinetobacter spp., doripenem (MIC(90) = 2, 89.1%S) was twice as active by MIC(90) as were imipenem and meropenem. Overall, doripenem potency was comparable to those of meropenem and imipenem against gram-positive cocci and doripenem was equal or superior in activity to meropenem and imipenem against Enterobacteriaceae, including beta-lactam-nonsusceptible isolates. Doripenem was the most active carbapenem tested against P. aeruginosa regardless of beta-lactam resistance.