Majority Of Symptomatic Infections Research Articles

Infections in liver transplantation: risk factors and strategies for prevention

Infection affects up to 70% of liver transplant recipients and is the second most common complication after rejection and graft dysfunction. Identified risk factors for infection include: previous transplantation; type of biliary anastomosis; transfusion requirements at surgery; surgical complications; duration of operation; duration of postoperative ventilation; serological status of donor and recipient; steroid use and serotherapy for rejection; and pre-and post-transplant antibiotic usage. The majority of symptomatic infections are bacterial and relate to surgery (intra-abdominal, biliary and wound infections), ventilation and intravenous cannulae. Cytomegalovirus infections occur in 45–100% of recipients but are asymptomatic in the majority. Fungal infections are mostly due to Candida albicans but infections due to Aspergillus spp. occur in approximately 6% and carry a high mortality. There are very few prospective comparative trials of antimicrobial prophylaxis in this patient population. The management of these patients needs to be based on such studies.

Procedure-related infections and preventive measures

Medical and surgical advances in the care of critically ill patients relyincreasingly on indwelling devices of various kinds. The prevention of nosocomial infections remains problematic in critical care patients because prosthetic devices represent an increasing risk of infection, impairing the natural defence mechanisms of the patients. Catheter-related urinary tract infection is the most common nosocomial infection and accounts for about 40% of all nosocomial infections. The diagnosis of urinary tract infection is simple in the majority of symptomatic infections, but becomes a problem in infections associated with low-count bacteriuria. In asymptomatic patients it is difficult to distinguish colonization from true bladder bacteriuria. The most common risk factors for the development of catheter-associated urinary tract infections are duration of catheterization, and microbial colonization of the catheter-drainage tube junction and the urethral and periurethral region. The most important measures for prevention of urinary tract infection are strict indications for urinary catheters, with suprapubic drainage being preferred; aseptic nursing techniques; closed sterile drainage systems; and early removal of the catheter. Nosocomial pneumonia represents 10–20% of all nosocomial infectionsand is often the final complication in hospitalized patients. The diagnosis of nosocomial pneumonia may be difficult, although a number of important technical advances have been developed (the use of protected brush techniques and bronchoalveolar lavage) to obtain optimal specimens for culture. Main risk factors for development of nosocomial pneumonia are intubation, nasogastric tube, enteral nutrition, colonization of the oropharynx, aspiration of potential pathogens and bacterial colonization of the gastric juices. Efforts to prevent nosocomial pneumonia include both oral decontamination regimens and specific stress ulcer prophylaxis. The most important hygienic measures for preventing ventilator-associated pneumonia are changing of masks and oxygen tubes after each patient, and hand washing before and after contact with respiratory secretions. The use of intravenous catheters is associated with the risk of iatrogenic infection, with a higher rate in patients undergoing central rather than peripheral venous catheterization. The diagnosis of catheter-related infection is established by isolation of the same organism from the catheter and the blood. Predisposing factors for intravascular device-related infections are duration of catheterization, catheter material, local infection, and presence of bacteria on the skin surrounding the insertion site, on the hub or in the infusate. Useful hygienic measures for prevention of intravascular infection are hand and skin disinfection before inserting cannulas, and changing dressings, administration sets and peripheral cannulas every 48–72 hours. To reduce the amount of infection related to invasive devices, new diagnostic and preventive methods should be evaluated. Incorporation of non-toxic antiseptics into the catheter and the development of new catheter materials may be the most promising approaches to reducing the incidence of device-related infection.

LABORATORY OUTBREAK OF Q FEVER ACQUIRED FROM SHEEP

In April and May, 1981, an outbreak of Q fever occurred in a university department which used gravid sheep for fetal respiratory studies. During the subsequent investigation 91 people were studied and 28 were found to have complement-fixing antibodies to the phase II antigen of Coxiella burneti in their serum. Symptoms compatible with C. burneti infection occurred in 14 of the seropositive patients. The majority of symptomatic infections could be related to the delivery of twin fetuses in one laboratory, but some people remote from this incident who were exposed to sheep in other parts of the building also showed evidence of infection. Those people with serological evidence of recent infection were treated with tetracycline for 4 weeks. Defects were apparent in the facilities being used for the research, and the risk of Q fever infection should be borne in mind by groups engaged in work with pregnant sheep.