Relatedness of penicillin-resistant Streptococcus pneumoniae serogroup 9 strains from France and Spain

Article Abstract:

A study of the genomic DNA of eleven clinical strains of Streptococcus pneumoniae exhibiting resistance to penicillin from Spain and France, by pulsed-field gel electrophoresis (FIGE), after digestion of intact chromosomes using restriction enzymes ApaI and SmaI, reveals a genetic relationship and a clonal origin among 10 of these strains with an entirely different eleventh strain. Clonal and independent events in a particular serotype contribute to the spread of penicillin resistance. The FIGE profiles of five strains resemble those of strains found in Spain, indicating the spread of a resistant strain to France from Spain.

Analysis, Physiological aspects, Drug resistance in microorganisms, Microbial drug resistance, Penicillin, Penicillins

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Genetic and physiological studies of the CiaH-CiaR two-component signal-transducing system involved in cefotaxime resistance and competence of Streptococcus pneumoniae

Article Abstract:

A mutation that causes the reversion of both cefotaxime resistance and transformation deficiency has been characterized. The ciaH mutation, a T/A deletion in the ciaR gene leading to the formation of a truncated protein with only 125 amino acids, needs a functional CiaR protein for expression. Northern blot analysis, which indicates that the ciaR and ciaH genes comprises an operon, has also pinpointed that Ca2+ acts as the environmental signal in the wild-type strain.

Antibiotics, Gene mutations, Gene mutation, Gene expression, Antibiotic structure-activity relationships, Cefotaxime

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Electrotransformation of Streptococcus pneumoniae: evidence for restriction of DNA on entry

Article Abstract:

The process of DNA penetration via electrotransformation in Streptococcus pneumoniae which lacks the natural mechanism for DNA uptake was investigated. DNA is strongly restricted by restriction endonucleases DpnI and DpnII acting on GATC sequences. Double-stranded DNA penetrates into these bacteria without being converted to one strand. Single-stranded DNA is able to yield transformants at a very reduced frequency and linear DNA produces very few transformants.

DNA

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