Antimicrobial Activity of Gallium Protoporphyrin IX against Acinetobacter baumannii Strains Displaying Different Antibiotic Resistance Phenotypes.

A paucity of effective, currently available antibiotics and a lull in antibiotic development pose significant challenges for treatment of patients with multidrug-resistant (MDR) Acinetobacter baumannii infections. Thus, novel therapeutic strategies must be evaluated to meet the demands of treatment of these often life-threatening infections. Accordingly, we examined the antibiotic activity of gallium protoporphyrin IX (Ga-PPIX) against a collection of A. baumannii strains, including nonmilitary and military strains and strains representing different clonal lineages and isolates classified as susceptible or MDR. Susceptibility testing demonstrated that Ga-PPIX inhibits the growth of all tested strains when cultured in cation-adjusted Mueller-Hinton broth, with a MIC of 20 µg/ml. This concentration significantly reduced bacterial viability, while 40 µg/ml killed all cells of the A. baumannii ATCC 19606(T) and ACICU MDR isolate after 24-h incubation. Recovery of ATCC 19606(T) and ACICU strains from infected A549 human alveolar epithelial monolayers was also decreased when the medium was supplemented with Ga-PPIX, particularly at a 40-µg/ml concentration. Similarly, the coinjection of bacteria with Ga-PPIX increased the survival of Galleria mellonella larvae infected with ATCC 19606(T) or ACICU. Ga-PPIX was cytotoxic only when monolayers or larvae were exposed to concentrations 16-fold and 1,250-fold higher than those showing antibacterial activity, respectively. These results indicate that Ga-PPIX could be a viable therapeutic option for treatment of recalcitrant A. baumannii infections regardless of the resistance phenotype, clone lineage, time and site of isolation of strains causing these infections and their iron uptake phenotypes or the iron content of the media.

A randomized trial to evaluate a launderable bed protection system for hospital beds.

BACKGROUND: Hospital beds are potential reservoirs of bacteria in hospitals. Preventing contamination of the bed and providing a cleaner surface should help prevent hospital-acquired infections (HAIs). Most hospital beds are cleaned between patients (terminal cleaning) using quaternary ammonia compounds (quats). OBJECTIVE: The study had two objectives: identify levels of bacterial contamination on beds (including the mattress and bed deck) and evaluate a new launderable cover. METHODS: Hospital beds on a bariatric surgery ward were randomized to either receive or not receive a launderable cover (Trinity Guardion, Batesville, IN). Bacterial counts on the surface of the mattress, the bed deck, and the launderable cover were then collected using Petrifilm™ Aerobic Count Plates (Petrifilm™, 3M™, St. Paul, MN, USA) (Petrifilm™) at three time periods (before patient use, after discharge, and after terminal cleaning). Standard hospital linen was used in all rooms. RESULTS: The launderable cover (n = 28) was significantly cleaner prior to patient use than were the cleaned mattresses (n = 38) (1.1 CFU/30 cm2 vs. 7.7 CFU/30 cm2; p = 0.0189). The mattresses without launderable covers became significantly contaminated during use (7.7 CFU/30 cm2 on admission vs. 79.1 CFU/30 cm2 after discharge; p < 0.001). The mattresses with launderable covers did not become contaminated (3.0 CFU/30 cm2 on admission vs. 2.5 CFU/30 cm2 at discharge; p = 0.703). After terminal cleaning, the mattress surface contamination decreased to 12.8 CFU/30 cm2 (median 3 CFU/30 cm2; SD 7.8), but the bed deck was more contaminated (6.7 CFU/30 cm2 after discharge compared to 30.9 CFU/30 cm2 after terminal cleaning; p = 0.031). CONCLUSIONS: Terminal cleaning fails to eliminate bacteria from the surface of the hospital mattress. The launderable cover provides a cleaner surface than does terminal cleaning with quats, and the cover protects the bed from contamination during use.