The objective was to develop and characterise in vitro Bartonella bacilliformis antibiotic resistant mutants. Three B. bacilliformis strains were plated 35 or 40 times with azithromycin, chloramphenicol, ciprofloxacin or rifampicin discs. Resistance-stability was assessed performing 5 serial passages without antibiotic pressure.

From its introduction in 1952 onwards, the clinical use of macrolides has been steadily increasing, both in human and veterinary medicine. Although initially designed to the treatment of Gram-positive microorganisms, this antimicrobial family has also been used to treat specific Gram-negative bacteria. Some of them, as azithromycin, are considered in the armamentarium against Enterobacteriaceae infections. However, the facility that this bacterial genus has to gain or develop mechanisms of antibiotic resistance may compromise the future usefulness of these antibiotics to fight against Enterobacteriaceae infections. The present review is focused on the mechanisms of macrolide resistance, currently described in Enterobacteriaceae.

En el presente estudio, se analizaron los mecanismos de resistencia a nitrofuranos en 18 muestras cárnicas con Salmonella enterica (15 de pollo, 2 de ternera y 1 de cerdo) de mercados de Lima (Perú). Determinaron los serotipos de los aislamientos y la sensibilidad a furazolidona y nitrofurantoina (con y sin el inhibidor de bombas de expulsión Phenyl-Arginine-β-Naphthylamide [PAβN]), las mutaciones en los genes snrA y cnr por PCR y la transferabilidad de la resistencia por conjugación. Se identificaron 15 muestras con S. infantis (13 muestras de pollo), 2 con S. enteritidis y 1 con S. anatum. Todos los aislamientos, excepto S. anatum, fueron resistentes a ambos nitrofuranos (concentración mínima inhibidora [CMI] a furazolidona: 32-64 μg/mL, CMI a nitrofurantoina: 128-256 μg/mL), sin diferencias al adicionarse PAβN. Todos los aislamientos resistentes a nitrofuranos presentaron s...

The objective of the present study was to characterize Salmonella enterica serovar Infantis isolated from chicken meat determining their clonal relationships with S. Infantis isolated from children with diarrhea. Fifteen meat-recovered S. Infantis were analyzed. Susceptibility levels to 14 antibacterial agents, the presence of ESBL and that of inducible plasmid-mediated AmpC (i-pAmpC) were determined by phenotypical methods. The presence of ESBL and pAmpC was confirmed by PCR, and detected ESBL-encoding genes were sequenced and their transferability tested by conjugation. The presence of gyrA mutations as well as Class 1 integrons was determined by PCR. Clonal relationships were established by REP-PCR and RAPD. In addition, 25 clinical isolates of S. Infantis were included in clonality studies. All meat-recovered S. Infantis were MDR, showing resistance to ampicillin, nitrofurans and qui...