[In vitro activity of ceftaroline against Spanish isolates of Staphylococcus aureus: a multicenter study]. / Estudio multicéntrico sobre la actividad in vitro de ceftarolina frente a Staphylococcus aureus aislados en España.

INTRODUCTION: Ceftaroline fosamil is a new-generation antimicrobial agent of cephalosporins subgroup. It is the first commercially available beta-lactam antibiotic that exhibits activity against methicillin-resistant Staphylococcus aureus (MRSA). The aim of this study is to determine the in vitro Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) values of ceftaroline against S.aureus strains (including MRSA). MATERIAL AND METHODS: A multicenter study involving four hospitals representative of the Spanish geography was performed. MIC and MBC values against both the methicillin-resistant and sensitive strains of S.aureus (MRSA and methicillin-sensitive S.aureus [MSSA]) were determined using a broth microdilution method. RESULTS: A total of 266 S.aureus strains were analyzed (95 MRSA and 171 MSSA). Ceftaroline bacterial sensitivity showed a mean MIC of 0.227 µg/ml (SD=0.146; range, 0.06 to 1 µg/ml). All MIC values of the 266 strains tested belonged to the sensitive category (value ≤ 1 µg/ml). Intermediate or resistant strains were not detected. MIC50 and MIC90 values for MRSA were 0.25 and 0.5 µg/ml, respectively (range=0.125-1 µg/ml). MSSA strains showed MIC50 and MIC90 values of 0.125 and 0.25 µg/ml, respectively (range=0.125-0.5 µg/ml). MBC50 and MBC90 values for MRSA were 0.5 and 1 µg/ml, respectively (range=0.125-1 µg/ml). MSSA strains showed MBC50 and MBC90 values of 0.25 and 0.25 µg/ml, respectively (range=0.125-0.5 µg/ml). CONCLUSION: Ceftaroline shows excellent in vitro activity against S.aureus, including MRSA strains. Therefore, this antibiotic may be a promising alternative for the treatment of infections caused by this bacterium.

Acidic Urine pH and Clinical Outcome of Lower Urinary Tract Infection in Kidney Transplant Recipients Treated with Ciprofloxacin and Fosfomycin.

Different factors, including antimicrobial resistance, may diminish the effectiveness of antibiotic therapy, challenging the management of post-transplant urinary tract infection (UTI). The association of acidic urine pH with microbiological and clinical outcomes was evaluated after fosfomycin or ciprofloxacin therapy in 184 kidney transplant recipients (KTRs) with UTI episodes by Escherichia coli (N = 115) and Klebsiella pneumoniae (N = 69). Initial urine pH, antimicrobial therapy, and clinical and microbiological outcomes, and one- and six-month follow-up were assessed. Fosfomycin was prescribed in 88 (76.5%) E. coli and 46 (66.7%) K. pneumoniae UTI episodes in the total cohort. When the urine pH ≤ 6, fosfomycin was prescribed in 60 (52.2%) E. coli and 29 (42.0%) K. pneumoniae. Initial urine pH ≤ 6 in E. coli UTI was associated with symptomatic episodes (8/60 vs. 0/55, p = 0.04) at one-month follow-up, with a similar trend in those patients receiving fosfomycin (7/47 vs. 0/41, p = 0.09). Acidic urine pH was not associated with microbiological or clinical cure in K. pneumoniae UTI. At pH 5, the ciprofloxacin MIC90 increased from 8 to >8 mg/L in E. coli and from 4 to >8 mg/L in K. pneumoniae. At pH 5, the fosfomycin MIC90 decreased from 8 to 4 mg/L in E. coli and from 512 to 128 mg/L in K. pneumoniae. Acidic urine is not associated with the microbiological efficacy of fosfomycin and ciprofloxacin in KTRs with UTI, but it is associated with symptomatic UTI episodes at one-month follow-up in E. coli episodes.