The bactericidal action of chloramphenicol against six Haemophilus influenzae type b isolates and six Escherichia coli K-1 isolates was compared. Cells were grown in antibiotic-free medium into the late-stationary and mid-exponential phases of growth, and inocula of 10(5) to 10(6) cells per ml were added to fresh media containing 1 or 10 micrograms of chloramphenicol per ml for H. influenzae is...

The glpTQ operon of Haemophilus influenzae type b (Hib) and nontypeable H. influenzae (NTHi) strains is highly conserved, except for a 1.4-kb glpTQ intergenic region that was found in most Hib strains. The presence of this intergenic region results in divergent glpTQ transcriptional profiles for Hib and NTHi where Hib strains appear to have evolved an alternative promoter for glpQ expression. B...

Natural competence is the genetically encoded ability of some bacteria to take up DNA from the environment. Although most of the incoming DNA is degraded, occasionally intact homologous fragments can recombine with the chromosome, displacing one resident strand. This potential to use DNA as a source of both nutrients and genetic novelty has important implications for the ecology and evolution o...

The ability of some bacteria to take up and recombine DNA from the environment is an important evolutionary problem because its function is controversial; although populations may benefit in the long-term from the introduction of new alleles, cells also reap immediate benefits from the contribution of DNA to metabolism. To clarify how selection has acted, we have characterized competence in nat...

Quorum signals are diffusible factors produced by bacteria that coordinate communal responses. For nontypeable Haemophilus influenzae (NTHi), a series of recent papers indicate that production and sensing of quorum signals are determinants of biofilm formation/maturation and persistence in vivo. In this mini-review I will summarize the current knowledge about quorum signaling/sensing by this or...

Plasmids that share homology with the Haemophilus influenzae chromosome transform wild-type cells more efficiently than they transform recombination-defective mutants. A 5.2-kilobase-pair chromosomal fragment containing the strA gene of H. influenzae was found to promote efficient plasmid establishment in recombination-defective mutants. A cis-acting element in the insert, called rpe for rec-le...

BACKGROUND Shared seasonal patterns, such as between influenza and some respiratory bacterial infections, can create associations between phenomena not causally related. OBJECTIVES To estimate the association of influenza with subsequent bacterial infections after full adjustment for confounding by seasonal and long-term trends. METHODS Time series of weekly counts of notified cases of inva...

Vaccination of infants with conjugated Haemophilus influenzae type b (Hib) vaccines has been proven to reduce Hib meningitis by 95% and pneumoniae by 20%. The routine use of Hib vaccine is facilitated by the introduction of combination vaccines into the EPI (Expanded Plan of Immunization). The objective of this study was to compare the immunogenicity and reactogenicity of an extemporaneously mi...

BACKGROUND Protracted bacterial bronchitis (PBB) and bronchiectasis are distinct diagnostic entities that share common clinical and laboratory features. It is postulated, but remains unproved, that PBB precedes a diagnosis of bronchiectasis in a subgroup of children. In a cohort of children with PBB, our objectives were to (1) determine the medium-term risk of bronchiectasis and (2) identify ri...

A new plasmid cloning vehicle (pDM2) was used to introduce a library of Haemophilus influenzae chromosomal fragments into H. influenzae. Transformants of the highly recombination-defective rec-1 mutant were more likely to contain exclusively recombinant plasmids after exposure to ligated DNA mixtures than was the wild type. pDM2 could replicate in Escherichia coli K-12.