Active immunization using exotoxin A confers protection against Pseudomonas aeruginosa infection in a mouse burn model

<p>Abstract</p> <p>Background</p> <p><it>Pseudomonas aeruginosa </it>is an important cause of nosocomial infection and may lead to septicemia and death. We evaluated the immunogenicity of semi-purified exotoxin A from the bacterium in a mouse burn model.</p> <p>Methods</p> <p>The toxoid was prepared from exotoxin A taken from toxigenic strains of <it>P. aeruginosa </it>(PA 103). 50 mice were immunized with the toxoid, burned with hot metal and infected with 1 × 10⁸CFU of toxigenic strains of <it>P. aeruginosa </it>(experimental group); 25 non-immunized mice were also burned and infected (control group). The mortality rate and presence of any exotoxin and <it>P. aeruginosa </it>in the sera, liver and spleen were determined.</p> <p>Results</p> <p>In the experimental group, 2 mice died before the burns were administered and were excluded from the study. The remainder (48 mice) were challenged with a lethal dose of <it>P. aeruginosa </it>and followed for 70 days. 3 of these mice died. Neither <it>P. aeruginosa </it>nor exotoxin A was not detected in the liver, spleen or sera of the surviving mice. The protective efficacy of toxoid vaccination was therefore 93.8%. In the control group, all mice died from bacteremia and septicemia, most (80%) within 6 days, and <it>P. aeruginosa </it>and exotoxin A were isolated from sera, spleen and liver.</p> <p>Conclusion</p> <p>Active immunization of mice using a semi-purified exotoxin A derived from <it>P. aeruginosa </it>was 93.8% effective at protecting mice from subsequent <it>P. aeruginosa </it>infections in a mouse burn model.</p

Bacterial Contamination of Mobile Phones Carried by Medical Staff in Maternity, Neonatal, and ICU Wards of Shahid Beheshti and Imam Sajjad Hospitals in Yasuj

The use of mobile phones by healthcare personnel, doctors, patients, and patients’ companions are unavoidable in health centers, especially in hospitals. Besides being rarely clean, the mobile phone is a potential reservoir of disease and pathogens and hospital infections on bedside of hospitalized patients. In this study, the microbial contamination of mobile phones and potential of transmitting infections and their antibiotic resistance pattern were investigated. In this descriptive cross-sectional study, a questionnaire was prepared to assess the importance of maternity, neonatal, and intensive care unit (ICU) staff attention to how to use and clean the cell phones in terms of valid sources. Samples were taken from 116 cell phones using a sterile swab. The standard plate count was used to detect the existing bacteria, and the antimicrobial resistance patterns of isolated bacteria were determined by standard methods. The microbial culture experiments indicated that 107 cell phones had microbial contamination, accounting for 92.24% of mobile phones. From 132 isolated strains, 115 strains (87.12%) were gram-positive while 17 were Gram-negative (12.88%). Furthermore, 67 (57.76%), 9 (7.7%), 4 (3.45%), 10 (8.62%), 12 (10.35%), 22 (19%), and 8 (6.9%) strains were coagulase-negative staphylococci, Pseudomonas aeruginosa, Staphylococcus aureus, Corynebacterium, Bacillus, Streptococcus, and Escherichia coli, respectively. The results of this study indicated that cell phones were contaminated with different types of bacteria, and that all species isolated partially played an important role in the development of hospital-acquired and opportunistic infections. Therefore, continuous disinfection of mobile phones and non-use or limited use of them in the hospitals are recommended