http://repub.eur.nl/res/aut/4725/ List of Publications en http://repub.eur.nl/static-eur/img/logo.png http://repub.eur.nl http://repub.eur.nl/res/pub/9821/ 2002-01-01T00:00:00Z Moraxella catarrhalis (formerly known as Branhamella catarrhalis) has emerged as a significant bacterial pathogen of humans over the past two decades. During this period, microbiological and molecular diagnostic techniques have been developed and improved for M. catarrhalis, allowing the adequate determination and taxonomic positioning of this pathogen. Over the same period, studies have revealed its involvement in respiratory (e.g., sinusitis, otitis media, bronchitis, and pneumonia) and ocular infections in children and in laryngitis, bronchitis, and pneumonia in adults. The development of (molecular) epidemiological tools has enabled the national and international distribution of M. catarrhalis strains to be established, and has allowed the monitoring of nosocomial infections and the dynamics of carriage. Indeed, such monitoring has revealed an increasing number of B-lactamase-positive M. catarrhalis isolates (now well above 90%), underscoring the pathogenic potential of this organism. Although a number of putative M. catarrhalis virulence factors have been identified and described in detail, their relationship to actual bacterial adhesion, invasion, complement resistance, etc. (and ultimately their role in infection and immunity), has been established in a only few cases. In the past 10 years, various animal models for the study of M. catarrhalis pathogenicity have been described, although not all of these models are equally suitable for the study of human infection. Techniques involving the molecular manipulation of M. catarrhalis genes and antigens are also advancing our knowledge of the host response to and pathogenesis of this bacterial species in humans, as well as providing insights into possible vaccine candidates. This review aims to outline our current knowledge of M. catarrhalis, an organism that has evolved from an emerging to a well-established human pathogen. http://repub.eur.nl/res/pub/8879/ 1998-01-01T00:00:00Z From 1 January 1995 until 1 January 1996, we studied the molecular epidemiology of blood isolates of coagulase-negative staphylococci (CoNS) in the Neonatal Intensive Care Units (NICUs) of the Sophia Children's Hospital (SCH; Rotterdam, The Netherlands) and the Wilhelmina Children's Hospital (WCH; Utrecht, The Netherlands). The main goal of the present study was to detect putatively endemic clones of CoNS persisting in these NICUs. Pulsed-field gel electrophoresis was used to detect the possible presence of endemic clones of clinical significance. In addition, clinical data of patients in the SCH were analyzed retrospectively to identify risk factors for the acquisition of positive blood cultures. In both centers, endemic CoNS clones were persistently present. Thirty-three percent of the bacterial isolates derived from blood cultures in the SCH belonged to a single genotype. In the WCH, 45% of all bacterial strains belonged to a single clone. These clones were clearly different from each other, which implies that site specificity is involved. Interestingly, we observe that the clonal type in the SCH differed significantly from the incidentally occurring strains with respect to both the average pH and partial CO2 pressure of the patient's blood at the time of bacterial culture. We found that the use of intravascular catheters, low gestational age, and a long hospital stay were important risk factors for the development of a putative CoNS infection. When the antibiotic susceptibility of the bacterial isolates was assessed, a clear correlation between the nature of the antibiotics most frequently used as a first line of defense versus the resistance profile was observed. We conclude that the intensive use of antibiotics in an NICU setting with highly susceptible patients causes selection of multiresistant clones of CoNS which subsequently become endemic.