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Several outbreaks of listeriosis have implicated fresh produce but genetic factors required for growth of Listeria monocytogenes on produce remain poorly characterized. Based on the fact that β-lactam antibiotics only kill bacterial cells that are growing, we hypothesized that ampicillin selection can enrich for L. monocytogenes mutants unable to grow on produce. For validation, we examined relative recovery of L. monocytogenes strain 2011L-2858 and its cold-sensitive mutant L1E4 following inoculation of cantaloupe rind fragments with 1:1 mixture of the strains and incubation at 4 °C with or without ampicillin. L. monocytogenes from rind fragments inoculated with the mixed cultures and incubated in the presence of ampicillin were used to inoculate fresh rind fragments for a second round of enrichment. In the presence of ampicillin, the proportion of L1E4 increased from 55% on day 0 to 78% on day 14, with higher recovery (85% after 14 days) in the second round of enrichment. These data suggested that L1E4 was enriched on cantaloupe rind fragments while growing cells of the wildtype were killed by ampicillin. Application of this protocol to transposon mutant libraries from three L. monocytogenes strains yielded several mutants unable to grow on cantaloupe. Thus, ampicillin selection can facilitate discovery of genes essential for growth of L. monocytogenes on fresh produce.
This article was published in the following journal.
Name: FEMS microbiology letters
A retrospective review of Listeria monocytogenes infection at Tygerberg Children's Hospital, Cape Town, South Africa, from 2006 to 2016: Is empirical ampicillin still indicated after the first month of life?
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Inflammation of the meninges caused by LISTERIA MONOCYTOGENES infection, usually occurring in individuals under the age of 3 years or over the age of 50 years. It may occur at any age in individuals with IMMUNOLOGIC DEFICIENCY SYNDROMES. Clinical manifestations include FEVER, altered mentation, HEADACHE, meningeal signs, focal neurologic signs, and SEIZURES. (From Medicine 1998 Sep;77(5):313-36)
An ester of AMPICILLIN which is readily hydrolysed on absorption to release ampicillin. It is well absorbed from the gastrointestinal tract resulting in a greater bioavailability of ampicillin than can be achieved with equivalent doses of ampicillin.
A species of gram-positive, rod-shaped bacteria widely distributed in nature. It has been isolated from sewage, soil, silage, and from feces of healthy animals and man. Infection with this bacterium leads to encephalitis, meningitis, endocarditis, and abortion.
Bacteriocins produced by species of PEDIOCOCCUS. They range from 3.5-4.6 kDa in mass, contain a conserved YGNGVXCXK motif and beta sheet at their N-terminals, and a more diverse hydrophobic or amphiphilic C-terminal alpha helical domain. They function as antimicrobial peptides against several pathogenic species of GRAM POSITIVE BACTERIA, including LISTERIA MONOCYTOGENES and are useful as FOOD PRESERVATIVES.
Nonsusceptibility of a microbe to the action of ampicillin, a penicillin derivative that interferes with cell wall synthesis.
Food is any substance consumed to provide nutritional support for the body. It is usually of plant or animal origin, and contains essential nutrients, such as carbohydrates, fats, proteins, vitamins, or minerals. The substance is ingested by an organism ...