RT Journal Article SR Electronic T1 IgM-enriched immunoglobulin improves colistin efficacy in a pneumonia model by Pseudomonas aeruginosa JF Life Science Alliance JO Life Sci. Alliance FD Life Science Alliance LLC SP e202101349 DO 10.26508/lsa.202101349 VO 5 IS 10 A1 Tania Cebrero-Cangueiro A1 Gema Labrador-Herrera A1 Marta Carretero-Ledesma A1 Soraya Herrera-Espejo A1 Rocío Álvarez-Marín A1 Jerónimo Pachón A1 José Miguel Cisneros A1 María Eugenia Pachón-Ibáñez YR 2022 UL https://www.life-science-alliance.org/content/5/10/e202101349.abstract AB We evaluated the efficacy of ceftazidime or colistin in combination with polyclonal IgM-enriched immunoglobulin (IgM-IG), in an experimental pneumonia model (C57BL/6J male mice) using two multidrug-resistant Pseudomonas aeruginosa strains, both ceftazidime-susceptible and one colistin-resistant. Pharmacodynamically optimised antimicrobials were administered for 72 h, and intravenous IgM-IG was given as a single dose. Bacterial tissues count and the mortality were analysed. Ceftazidime was more effective than colistin for both strains. In mice infected with the colistin-susceptible strain, ceftazidime reduced the bacterial concentration in the lungs and blood (−2.42 and −3.87 log10 CFU/ml) compared with colistin (−0.55 and −1.23 log10 CFU/ml, respectively) and with the controls. Colistin plus IgM-IG reduced the bacterial lung concentrations of both colistin-susceptible and resistant strains (−2.91 and −1.73 log10 CFU/g, respectively) and the bacteraemia rate of the colistin-resistant strain (−44%). These results suggest that IgM-IG might be useful as an adjuvant to colistin in the treatment of pneumonia caused by multidrug-resistant P. aeruginosa.