PubMed · 4175555
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1968-10-05. Methicillin-resistant staphylococci.. https://pubmed.ncbi.nlm.nih.gov/4175555/
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Ampicillin is one of the most common drugs to elicit a rash, with an overall incidence of 3% to 8%. "Ampicillin-specific" rashes are thought to be nonhypersensitivity reactions and cause maculopapular erythema with minimal irritation or pruritus. If the rash is indeed an ampicillin-specific one, then discontinuation of ampicillin is not mandatory, and subsequent use of ampicillin or other beta-lactam antibiotics is tolerated. On the other hand, true hypersensitivity reactions with urticarial and anaphylactic properties demand prompt discontinuation of the drug and warrant supportive care. Unfortunately, there is no immediate definitive scientific method to differentiate between the two.
The efficacy of treatment with a combination of ampicillin, imipenem, and vancomycin was compared with that of two-drug combinations or monotherapy in a model of experimental endocarditis using a strain of Enterococcus faecium with high-level resistance to vancomycin and moderate intrinsic resistance to ampicillin and imipenem. In vitro time-kill synergy studies demonstrated bactericidal synergistic activity only for the triple combination. In vivo, monotherapy with vancomycin was not effective. Treatment with either ampicillin or imipenem alone or in combination with vancomycin resulted in <4 log10 reduction in colony-forming units (cfu) per gram of vegetation. The combination of ampicillin with imipenem was highly active (an additional 5 log10 reduction in cfu per gram of vegetation compared with the most active single agent), but efficacy was not increased by the addition of vancomycin to ampicillin and imipenem. Therapy with the combination of ampicillin and imipenem may be effective for some strains of multidrug-resistant enterococcal infections.
The intracellular distribution of (3H)ampicillin-loaded polyisohexylcyanoacrylate nanoparticles was studied in murine macrophages (peritoneal cells and the J774 cell line) infected by Salmonella typhimurium C5, using ultrastructural autoradiography. Ampicillin penetration and retention into the cells obviously increased by means of nanoparticles. After short-term (2-4 h) treatment with the nanoparticle formulation, numerous intracellular bacteria were seen to be in the process of destruction. The tritium labelling was located in the cell cytoplasm and inside vacuoles in which bacteria undergoing degradation were often present. After long-term (12 h) treatment, numerous spherical bodies (d: 100 nm to 500 nm) and larger forms (2 microns) were seen in the vacuoles. Radioactivity was mainly found to be localized on the spherical bodies, indicating marked damaging action of the ampicillin on the bacterial walls. The targeting of ampicillin therefore allowed its penetration into the macrophages and vacuoles infected with S. typhimurium.