The type III secretion system of Pseudomonas aeruginosa transports four known effector proteins : ExoS, ExoT, ExoU and ExoY. However, the prevalence of the type III secretion system genes or the effector-encoding genes in clinical and environmental isolates of P. aeruginosa has not been well studied. Southern hybridization analyses and PCR were performed on over 100 P. aeruginosa isolates to determine the distribution of these genes. Clinical isolates were obtained from urine, endotracheal, blood and wound specimens, from the sputum of cystic fibrosis (CF) patients, and from non-hospital environmental sites. The popB gene was used as a marker for the presence of the large chromosomal locus encoding the type III secretion machinery proteins. Each isolate contained the popB gene, indicating that at least a portion of this large chromosomal locus was present in all isolates. Likewise, each isolate contained exoT-like sequences. In contrast, the exoS, exoU and exoY genes were variable traits. Overall, 72 % of examined isolates contained the exoS gene, 28 % contained the exoU gene, and 89 % contained the exoY gene. Interestingly, an inverse correlation was noted between the presence of the exoS and exoU genes in that all isolates except two contained either exoS or exoU but not both. No significant difference in exoS, exoU or exoY prevalence was observed between clinical and environmental isolates or between isolates cultured from different disease sites except for CF respiratory isolates. CF isolates harboured the exoU gene less frequently and the exoS gene more frequently than did isolates from some of the other sites of infection, including the respiratory tract of patients without CF. These results suggest that the P. aeruginosa type III secretion system is present in nearly all clinical and environmental isolates but that individual isolates and populations of isolates from distinct disease sites differ in their effector genotypes. The ubiquity of type III secretion genes in clinical isolates is consistent with an important role for this system in human disease. Keywords : ExoU, ExoY, ExoS, ExoT, cystic fibrosis INTRODUCTIONPseudomonas aeruginosa is a Gram-negative bacterium that causes a variety of diseases in compromised hosts. For example, this organism first colonizes the lungs of children with cystic fibrosis (CF) between 5 and 9 years of age (Pedersen et al., 1986) cultured from the sputum of approximately 80 % of adults over the age of 25 (Fitzsimmons, 1993). Once established within the lungs, P. aeruginosa usually causes episodic bouts of pneumonia that lead to progressive irreversible lung injury and ultimately death. Another group of individuals particularly prone to infections by this organism is hospitalized patients. In the United States, it is estimated that P. aeruginosa is responsible for 17 % of nosocomial pneumonias, 11 % of nosocomial urinary tract infections, 8 % of surgical H. FELTMAN and OTHERS wound infections and 3 % of central-line-associated bloodstream infections (National Nosocomi...

Treatment of symptomatic (but not asymptomatic) patients with metronidazole or vancomycin for 10 days is effective; metronidazole may be preferred to reduce risk of vancomycin resistance among other organisms in hospitals. Recurrence of symptoms occurs in 7% to 20% of patients and is due to both relapse and reinfection. Over 90% of first recurrences can be treated successfully in the same manner as initial cases. Combination treatment with vancomycin plus rifampin or the addition orally of the yeast Saccharomyces boulardii to vancomycin or metronidazole treatment has been shown to prevent subsequent diarrhea in patients with recurrent disease.

To investigate the transmission of influenza viruses via hands and environmental surfaces, the survival of laboratory-grown influenza A and influenza B viruses on various surfaces was studied. Both influenza A and B viruses survived for 24-48 hr on hard, nonporous surfaces such as stainless steel and plastic but survived for less than 8-12 hr on cloth, paper, and tissues. Measurable quantities of influenza A virus were transferred from stainless steel surfaces to hands for 24 hr and from tissues to hands for up to 15 min. Virus survived on hands for up to 5 min after transfer from the environmental surfaces. These observations suggest that the transmission of virus from donors who are shedding large amounts could occur for 2-8 hr via stainless steel surfaces and for a few minutes via paper tissues. Thus, under conditions of heavy environmental contamination, the transmission of influenza virus via fomites may be possible.

Background:The effect of large-scale expanded surveillance for methicillin-resistant Staphylococcus aureus (MRSA) on health careassociated MRSA disease is not known.