Search results for "ampicillin"

Evolutionary rescue of bacteria via horizontal gene transfer under a lethal β-lactam concentration

2013

β-Lactams are a commonly used class of bactericidal antibiotics. The number of β-lactam-resistant pathogens is constantly increasing in hospitals around the world. Interestingly, most of the β-lactam-resistant bacteria carry mobile genetic elements, such as conjugative plasmids, that render the pathogen resistant. These elements mediate their own transfer from one bacterium to another, producing new resistant strains via horizontal gene transfer. Here we investigated whether it is possible that transfer of the resistance element from another bacterium may evolutionarily rescue a susceptible bacterium exposed to a lethal concentration of the β-lactam ampicillin. Indeed, the rescuing occurs e…

Influence of Haemophilus influenzae β-lactamase production and/or ftsI gene mutations on in vitro activity of and susceptibility rates to aminopenici…

2007

Multidrug and broad-spectrum cephalosporin resistance among Salmonella enterica serotype enteritidis clinical isolates in southern Italy.

2002

ABSTRACT From 1992 to 1997, only six sporadic isolates of Salmonella enterica serotype Enteritidis from patients with cases of gastroenteritis in southern Italy exhibited resistance to broad-spectrum cephalosporins. Five isolates produced SHV-12, and one isolate encoded a class C β-lactamase. The bla SHV-12 gene was located in at least two different self-transferable plasmids, one of which also carried a novel class 1 integron.

Antibiotic susceptibility of cocultures in polymicrobial infections such as peri-implantitis or periodontitis: an in vitro model.

2011

Although polymicrobial infections, such as peri-implantitis or periodontitis, were postulated in the literature to be caused by synergistic effects of bacteria, these effects remain unclear looking at antibiotic susceptibility. The aim of this study is to compare the antibiotic susceptibilities of pure cultures and definite cocultures.Laboratory strains of Aggregatibacter actinomycetemcomitans (Aa) (previously Actinobacillus actinomycetemcomitans), Capnocytophaga ochracea (Co), and Parvimonas micra (Pm) (previously Peptostreptococcus micros) were cultivated under anaerobic conditions, and their susceptibilities to 10 antibiotics (benzylpenicillin G, ampicillin, amoxicillin, ampicillin/sulba…

Characterization of endemic Shigella boydii strains isolated in Iran by serotyping, antimicrobial resistance, plasmid profile, ribotyping and pulsed-…

2008

Background: Shigellosis is one of the major causes of morbidity in children with diarrhea in Iran. The present study was undertaken to characterize apparently sporadic Shigella boydii strains isolated from pediatric patients in Iran. Findings: Ten S. boydii strains isolated from pediatric cases of gastroenteritis and acute diarrhea in Tehran between December 2002 and November 2003 were submitted to serotyping, antimicrobial susceptibility testing, plasmid profile analysis, ribotyping and pulsed field gel electrophoresis (PFGE). Seven isolates were attributed to serotype 2, whereas the remaining three belonged to serotypes 14, 18, 19, respectively. Six drug resistance phenotypes (R1 to R6) w…

Description of an improved method for Blastocystis hominis culture and axenization

1996

An improved method for Blastocystis hominis culture and axenization was developed in the present study. Stool samples were cultured in prereduced Boeck-Drbohlav NHI modified medium (with several modifications) supplemented with antibiotics (0.4% ampicillin, 0.1% streptomycin, 0.0006% amphotericin B). Axenization was performed by the combination of partial purification of B. hominis by Ficoll-metrizoic acid gradient and inoculation in fresh medium containing active antibiotics against remaining bacteria. A total of 25 strains were obtained by this procedure. The time required for axenization ranged between 3 and 5 weeks. The generation time of axenic strains ranged from 6.6 to 12.1 h (mean +…

Multiple Resistance to Betalactam Antibiotics, Azithromycin or Moxifloxacin in Implant Associated Bacteria

2013

Background Antibiotics are more and more frequently prescribed in dentistry for prevention and treatment of oral diseases. Bacterial resistance to these agents is clearly increasing, including even previously susceptible micro-organisms and true pathogens. The aim of the present investigation was to examine resistant bacterial strains with respect to possible multiple antibiotic resistance. Methods In a previous investigation, implant-associated bacteria were tested first as mixed cultures and again as pure isolates (n = 138) for resistance to one of five antibiotics (ampicillin/AM, ampicillin + sulbactam/AB, azithromycin/AZ, penicillin/PG, moxifloxacin/MX) using the Etest. The resistance o…