Mucoid Pseudomonas aeruginosa is isolated from most patients with cystic fibrosis, in whom it causes a chronic, incurable lung infection. Bronchopulmonary disease is the cause of death in 95% of patients with cystic fibrosis,'2 and mucoid P aeruginosa was cultured from 94% of Danish patients with cystic fibrosis at death.3 Typically the airways are colonised initially with non-mucoid strains of P aeruginosa" and after a variable period of colonisation, usually one to two years, mucoid strains emerge that produce large amounts of the extracellular polysaccharide alginate. Compared with non-mucoid strains, infection with mucoid P aeruginosa is associated with a poorer clinical state,6 lower pulmonary function,78 and greater risk of death.7Infection with mucoid strains was also associated with an increased humoral immune response to P aeruginosa.`0 An increased antibody response is associated with poorer pulmonary function7"' and the lung damage in cystic fibrosis is mediated by immune complexes.'213 This suggests that alginate is a virulence factor in chronic P aeruginosa pulmonary infection in cystic fibrosis.'4Our objective was to test the hypothesis that alginate producing, mucoid P aeruginosa is more virulent than non-mucoid strains. We studied 73 patients with cystic fibrosis classified according to their sputum bacteriology longitudinally and determined their antibody responses to P aeruginosa alginate and somatic antigens, lung function, and nutritional state for three years before and for up to 10 years after the onset of chronic P aeruginosa lung infection. Patients and methodsThe diagnosis of cystic fibrosis was based on repeatedly raised electrolyte concentrations in sweat and characteristic clinical features. The criteria for entry into the study were that the onset of chronic P aeruginosa infection was after 1975, that the patient had been followed up monthly at the Danish Cystic Fibrosis Centre at Rigshospitalet before the onset of infection, and that sputum bacteriology had been recorded for at least eight months of each year. Data were recorded prospectively and included forced vital capacity (FVC), height, weight, and sputum bacteriology. Since 1976 all patients with chronic P aeruginosa infection have been admitted to the centre every three months for intravenous courses of antipseudonomas chemotherapy.'5 BACTERIOLOGY The onset ofchronic P aeruginosa infection was defined as the time when P aeruginosa had been grown in consecutive monthly sputum cultures over six months.

Focus eradication and the dosing of penicillinase-stable penicillin are important to the outcome of S aureus bacteremia. We recommend treatment with at least 1 g of penicillinase-stable penicillins 4 times daily for longer than 14 days.

The present study was undertaken to investigate the frequency of the nasal carrier rate of Staphylococcus aureus. The investigation was performed on 104 healthy persons. The total number of swabs performed was 1498 and this resulted in isolation of 522 S. aureus strains. All strains have been identified, tested for antibiotic susceptibility, and phage-typed. The carrier-index (number of positive swabs/number of total swabs for each individual person) was compared with different sampling and culturing methods, phage type, age, and resistance to antibiotics. There was statistical difference in carrier rate according to sex (P < 0.05). Among the 104 persons 15 (14.4%) were persistent carriers, 17 (16.3%) intermittent carriers, 55 (52.9%) occasional carriers and 17 (16.3%) non-carriers. Among intermittent and occasional carriers the phage-type distribution was different from the S. aureus strains isolated from Danish hospitalized patients in 1992, while the persistent carriers had similar phage-type distribution.

Agrobacterium species and Ochrobactrum anthropi are generally considered innocuous in clinical settings, yet during the last decade a number of sporadic cases of human infection due to these organisms have been reported. We studied nine cases of infection (septicemia and peritonitis) caused by Agrobacterium-like microorganisms in eight patients. All patients were immunocompromised and had permanent central venous or peritoneal dialysis catheters in place. Seven patients were women, and eight infections were community acquired. Six isolates were identified as Agrobacterium species and three as O. anthropi. These two groups of strains differed in the production of beta-galactosidase and of acid from lactose, erythritol, salicin, and cellobiose. All strains were strictly aerobic, peritrichous, gram-negative bacilli that produced oxidase, urease, and acid from glucose, fructose, arabinose, xylose, mannitol, inositol, and ethanol. The in vitro adherence of isotope-labeled bacteria to silicone tubes was similar to that of staphylococci. We conclude that Agrobacterium species and O. anthropi can be pathogenic in immunocompromised patients with permanent catheters.