Cebrero-Cangueiro, TaniaLabrador-Herrera, GemaCarretero-Ledesma, MartaHerrera-Espejo, SorayaÁlvarez-Marín, RocíoPachón, JerónimoCisneros, José MiguelPachón-Ibáñez, María Eugenia2023-05-032023-05-032022-06-21http://hdl.handle.net/10668/21801We 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.enAttribution 4.0 Internationalhttp://creativecommons.org/licenses/by/4.0/AnimalsAnti-Bacterial AgentsCeftazidimeColistinDrug Resistance, Multiple, BacterialImmunoglobulin MMaleMiceMice, Inbred C57BLPneumoniaPseudomonas InfectionsPseudomonas aeruginosaresearch article35728946open access10.26508/lsa.2021013492575-1077PMC9214247https://www.life-science-alliance.org/content/lsa/5/10/e202101349.full.pdfhttps://www.ncbi.nlm.nih.gov/pmc/articles/PMC9214247/pdf