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R J Pinney

Publications and source records attributed to R J Pinney.

59 records · Page 4Linked to original sources
PubMedDate not supplied

Post-antibiotic effects of ofloxacin on Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus, and Streptococcus pyogenes.

A viable counting technique was used to determine the post-antibiotic effect (PAE) of ofloxacin against four bacterial species, treated with either once of four times the minimum inhibitory concentration for 1 or 3 h. Similar to the results obtained previously with ciprofloxacin, ofloxacin gave PAE values with Escherichia coli, Staphylococcus aureus, and Streptococcus pyogenes. Cell division of Klebsiella pneumoniae was inhibited on removal of ofloxacin, but no clear PAE was demonstrated with this species because once replication recommenced, the mean generation times of drug-treated cultures were much shorter than those of untreated controls. Therefore, although the results obtained with ciprofloxacin and ofloxacin imply a consistency of PAE for 4-quinolones within a species, the response to DNA damage induced by 4-quinolones is multifaceted and species dependent. 4-quinolones inhibit both DNA replication and cell division, whilst at the same time stimulating DNA repair pathways. Thus, in some cases PAEs result from an increased post-treatment lag phase which may be followed by nearly normal multiplication, whereas in other cases a long lag may be followed by abnormally rapid cell division, with the generation times of treated cultures being shorter than those of corresponding drug-free controls. The PAE of a drug-induced lag may thus be masked by rapid cell division once growth resumes.

Colony Count, Microbial↗
PubMedDate not supplied

Post-antibiotic effects of cefdinir on Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus and Streptococcus pyrogenes.

The post-antibiotic effects (PAEs) of a new cephalosporin, cefdinir, were determined against a range of organisms using a viable counting technique. Cefdinir exerted considerable PAEs against Staphylococcus aureus and Streptococcus pyogenes, but no overall post-antibiotic inhibition of growth was detected against Escherichia coli or Klebsiella pneumoniae. Exposure to cefdinir made the gram-negative organisms susceptible to the washing procedure used for drug removal, but this was followed by rapid recovery of viability in drug-free broth.

Cefdinir↗