Search PubMed⌕ Search

Biomedical subjects

Fernando Baquero

Publications and source records attributed to Fernando Baquero.

78 records · Page 5Linked to original sources
PubMed1999

In vitro selective concentrations of cefepime and ceftazidime for AmpC beta-lactamase hyperproducer Enterobacter cloacae variants.

This study aimed to compare the selective concentrations of cefepime and ceftazidime on Enterobacter cloacae. A mixed culture of a wild-type ceftazidime/cefepime-susceptible (4x107 CFU/mL) strain and an ampC derepressed Enterobacter cloacae (105 CFU/mL) strain (relative proportions 99.75% and 0.25%) was challenged for 4 h with different antibiotic concentrations of ceftazidime and cefepime (0.03--4096 mg/L), and then transferred to drug-free medium. The proportion of wild-type versus derepressed population was evaluated after 24 h. Ceftazidime and cefepime selected the derepressed variant at concentrations ranging from 1 to 4096 and from 0.12 to 16 mg/L respectively. These results suggest that serum concentrations attainable with a 2 g/8 h cefepime dosage may be able to suppress the emergence of derepressed ampC mutants.

Journal Article↗
PubMed1998

In vitro selective concentrations of cefepime and ceftazidime for AmpC beta-lactamase hyperproducer Enterobacter cloacae variants.

METHODS: A mixed culture of a wild-type ceftazidime/cefepime-susceptible (4x107 CFU/mL) strain and an ampC derepressed Enterobacter cloacae (105 CFU/mL) strain (relative proportions 99.75% and 0.25%) was challenged for 4 h with different antibiotic concentrations of ceftazidime and cefepime (0.03-4096 mg/L), and then transferred to drug-free medium. The proportion of wild-type versus derepressed population was evaluated after 24 h. RESULTS: Ceftazidime and cefepime selected the derepressed variant at concentrations ranging from 1 to 4096 and from 0.12 to 16 mg/L respectively. CONCLUSIONS: These results suggest that serum concentrations attainable with a 2 g/8 h cefepime dosage may be able to suppress the emergence of derepressed ampC mutants.

Journal Article↗
PubMed1997

Current patterns and evolution of antibiotic resistance among bacterial pathogens involved in acute otitis media.

Penicillin resistance among Streptococcus pneumoniae is becoming a global problem. Different evolutionary phases in the development of resistance can be differentiated according to the local distribution of bacterial strains with different levels of penicillin resistance: susceptible, early phase, low-level resistance phase, multipopulational phase, high-level resistance phase and very high-level resistance phase. These phases evolve in different periods (cryptic, penetration period, evolutionary period and stationary period) which describe the presumed natural history of the resistant organisms. The selective effect of the antibiotic usage depends on the amount and type of the drug, and also on the evolutionary period dominating the geographic area where the antibiotic is used. Macrolide resistance is also a growing problem, probably proportional to the amount of drug used. In the case of beta-lactams, 'more is different' strategies may be useful to control clinically low-level resistant strains with aminopenicillins, and could slow the evolution to higher rates of resistance in some areas; nevertheless, surveillance of the evolution of high-level resistance is mandatory. In Haemophilus influenzae, the proportion of beta-lactamase-positive strains is also very high, frequently over 25% of cases; in all cases the combination amoxycillin---clavulanate restores the susceptible phenotype. In this case, surveillance should be focused on the increase in non-beta-lactamase-mediated penicillin resistance and fluoroquinolone resistance, or in the potential evolution towards extended-spectrum beta-lactamases.

Journal Article↗
PubMed1996

Bacteriologic diagnosis of respiratory tract infections.

The use of the Gram stain for determination of the presence of bacteria in respiratory secretions is described. Success of the procedure depends on the use of fresh samples of high cellular quality. The Gram stain can be used to distinguish the presence (among other organisms) of Streptococcus pneumoniae, Haemophilus influenzae, Branhamella catarrhalis enterobacteria and Pseudomonas. This paper also discusses the use of sputum samples for bacteriologic culture and the value of bacterial counts in expectorated sputum, and describes the use of transtracheal aspiration and transthoracic aspiration puncture. Finally, it considers the optimum procedures for the testing of antibiotic susceptibility of presumptive pathogens isolated from the lower respiratory tract.

Journal Article↗