Expression of Efflux Pump Gene pmrA in Fluoroquinolone-Resistant and -Susceptible Clinical Isolates of Streptococcus pneumoniae
| Autor: | M. M. Johnson, S. Simjee, Laura J. V. Piddock, Lilian Pumbwe |
|---|---|
| Rok vydání: | 2002 |
| Předmět: |
Tetracycline
Microbial Sensitivity Tests Biology medicine.disease_cause Microbiology chemistry.chemical_compound Anti-Infective Agents Bacterial Proteins Ciprofloxacin Mechanisms of Resistance Streptococcus pneumoniae medicine Pharmacology (medical) Norfloxacin Antibacterial agent Pharmacology Reverse Transcriptase Polymerase Chain Reaction Chloramphenicol Drug Resistance Microbial biochemical phenomena metabolism and nutrition Blotting Northern RNA Bacterial Infectious Diseases DNA Topoisomerases Type I chemistry Acriflavine Efflux Ethidium bromide medicine.drug |
| Zdroj: | Antimicrobial Agents and Chemotherapy. 46:808-812 |
| ISSN: | 1098-6596 0066-4804 |
| DOI: | 10.1128/aac.46.3.808-812.2002 |
| Popis: | Thirty-four ciprofloxacin-resistant (MIC ≥ 2 μg/ml) and 12 ciprofloxacin-susceptible clinical isolates of Streptococcus pneumoniae were divided into four groups based upon susceptibility to norfloxacin and the effect of reserpine (20 μg/ml). The quinolone-resistance-determining regions of parC , parE , gyrA , and gyrB of all ciprofloxacin-resistant clinical isolates were sequenced, and the activities of eight other fluoroquinolones, acriflavine, ethidium bromide, chloramphenicol, and tetracycline in the presence and absence of reserpine were determined. Despite a marked effect of reserpine upon the activity of norfloxacin, there were only a few isolates for which the activity of another fluoroquinolone was enhanced by reserpine. For most isolates the MICs of acriflavine and ethidium bromide were lowered in the presence of reserpine despite the lack of effect of this efflux pump inhibitor on fluoroquinolone activity. The strains that were most resistant to the fluoroquinolones were predominantly those with mutations in three genes. Expression of the gene encoding the efflux pump PmrA was examined by Northern blotting (quantified by quantitative competitive reverse transcriptase PCR) and compared with that of S . pneumoniae R6 and R6N. Within each group there were isolates that had high-, medium-, and low-level expression of this gene; however, increased expression was not exclusively associated with those isolates with a phenotype suggestive of an efflux mutant. These data suggest that there is another reserpine-sensitive efflux pump in S . pneumoniae that extrudes ethidium bromide and acriflavine but not fluoroquinolones. |
| Databáze: | OpenAIRE |
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