Observations of resistance through minimum inhibitory concentrations trends for respiratory specimens of commonly isolated organisms

Antimicrobial susceptibilities of respiratory pathogens in the surgical/trauma intensive care unit compared with the hospital-wide respiratory antibiogram in a level I trauma center

BACKGROUND

Unit-specific antibiograms have developed to guide clinicians to appropriate antibiotic choices for subsets of patients. The additional level of a unit- and respiratory-specific antibiogram for surgical and trauma patients defines key differences in susceptibility information for treating hospital-acquired pneumonia.

METHODS

This was a three-year, retrospective single-center study. A total of 729 positive respiratory specimens from 612 patients were analyzed using Quality Compass Pathfinder(®), the antibiotic-reporting software. Culture and susceptibility reports were compared for the surgical/trauma intensive care unit (S/TICU) and the general hospital (excluding the S/TICU but including the medical ICU [MICU]). Data were filtered to include those genera and organisms with a high association with hospital-acquired pneumonia: Acinetobacter, Citrobacter, Enterobacter, Escherichia coli, Haemophilus, Klebsiella, Neisseria, Pseudomonas, Staphylococcus, Stenotrophomonas, Streptococcus, and Serratia.

RESULTS

For gram-negative organisms, susceptibility differences were noted for Acinetobacter and Pseudomonas between the S/TICU and the rest of the hospital. In particular, Acinetobacter was significantly more susceptible to ciprofloxacin (86% vs. 43%; p<0.001), gentamicin (86% vs. 54%; p=0.001), imipenem-cilastatin (93% vs. 55%; p<0.001), trimethoprim-sulfamethoxazole (88% vs. 54%; p=0.001), and tobramycin (50% vs. 0; p=0.012). Pseudomonas isolates from the S/TICU were significantly more susceptible to aztreonam (83% vs. 68%; p=0.037), ciprofloxacin (86% vs. 69%; p=0.019), and imipenem-cilastatin (94% vs. 79%; p=0.01). For gram-positive organisms, Staphylococcus isolates from the S/TICU were significantly more susceptible to erythromycin (81% vs. 57%; p=0.007) and trimethoprim-sulfamethoxazole (98% vs. 91%; p=0.034) than were the hospital isolates.

CONCLUSIONS

For key respiratory pathogens, such as Pseudomonas, Acinetobacter, and Staphylococcus, surgical and trauma patients present greater susceptibility to several antibiotics. Although this information cannot be extrapolated to other institutions, it does provide a basis for comparable institutions to consider developing unit- and collection-site-specific antibiograms for infections that affect surgical/trauma patients commonly.