Journal of medical microbiology
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Review
Moraxella (Branhamella) catarrhalis--clinical and molecular aspects of a rediscovered pathogen.
Since its discovery at the end of the nineteenth century, Moraxella (Branhamella) catarrhalis has undergone several changes of nomenclature and periodic changes in its perceived status as either a commensal or a pathogen. Molecular analysis based on DNA hybridisation or 16S rDNA sequence comparisons has established its phylogenetic position as a member of the Moraxellaceae and shown that it is related more closely to Acinetobacter spp. than to the genus Neisseria in which it was placed formerly. However, confusion with phenotypically similar Neisseria spp. can occur in the routine diagnostic laboratory if appropriate identification tests are not performed. ⋯ Increased understanding of the organism's pathogenic properties and the host response to it may help to identify suitable vaccine targets or lead to other strategies to prevent infection. Whilst it remains, at present, the third most important respiratory pathogen, the impact of immunisation strategies for other organisms may change this position. The speed with which M. catarrhalis acquired beta-lactamase demonstrates the capacity of this organism to surprise us.
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The production of virulence factors was determined quantitatively for clinical isolates of methicillin-resistant (MRSA) and methicillin-sensitive (MSSA) strains of Staphylococcus aureus from The London Hospital. The examined factors were: production of enterotoxins A, B, C and D, determined by ELISA; quantitation and differentiation of the membrane-damaging alpha, beta, gamma and delta haemolysins; and coagulase production determined by a chromogenic assay. ⋯ MRSA and MSSA were compared in a phagocytosis assay but there was no difference between the phagocytosis of MRSA and MSSA by human polymorphonuclear leucocytes. These findings indicate that MRSA from The London Hospital is at least as well equipped to cause disease as other isolates of S. aureus, and probably better equipped than most hospital isolates of MSSA.