Infections in the compromised host

The skin and/or mechanical factors, such as coughing, ciliary action or urine flow, along with phagocytes and humoral and cell-mediated immunity, help to protect the body from infection. In compromised patients, these mechanisms are impaired or bypassed, rendering patients susceptible to infection by opportunistic organisms (bacteria, mycobacteria, fungi, viruses, parasites). Mechanical barriers may be breached in patients with burns or indwelling catheters, in diabetics or cancer patients, and in parenteral drug abusers. Humoral or cell-mediated immunity may be suppressed in non-neoplastic patients following splenectomy, in diabetics, in alcoholics and in those with certain rheumatic disorders, as well as in patients undergoing haemodialysis or receiving steroids or immunosuppressive drugs. In cancer patients infection is often a cause of death, frequently occurring as a result of granulocytopenia, obstruction of natural passages, or suppression or dysfunction of humoral or cell-mediated immunity. Diagnosis of the infection may be difficult and expert advice should be sought. Treatment should be started before a conclusive diagnosis has been made, particularly in neutropenic patients since infections may be life-threatening.     

Infections in the compromised host.

The normal defense mechanisms against infection include (1) normal skin and mucous membranes, (2) humoral immunity, (3) phagocytic system, and (4) cellular immunity. The compromised (immunocompromised) host is an individual who has one or more deficiencies in these defense mechanisms. This article reviews potential infections in the compromised host as well as an approach to evaluation of these patients.     

Infections in the alcoholic

Serious infections appear to occur more frequently in alcoholic patients. However, whether this is due to the effects of alcohol per se or to the other frequent complications of alcoholism--nutritional deficiencies, cirrhosis, and poor hygiene--has not been determined. The host factors that may underlie an increased frequency of infection in alcoholics and the clinical infectious syndromes associated with alcoholism are described.     

Viral Infections in the Neonate

Maternal to child transmission of viral infections can have devastating outcomes on the developing fetus and the neonate. Effective prevention and screening programs for women of childbearing age are key factors in influencing the outcomes for the neonate. Furthermore, early identification of viral infections in neonates is critical to the success of the treatment plan. This article describes the mechanism of maternal to child transmission of viral infections and examines the general approach to the neonate with suspected viral infection. The diagnosis, treatment, and prevention of neonatal cytomegalovirus, herpes simplex virus, and human immunodeficiency virus infections are presented. Lastly, current challenges and controversies related to the management of viral infections in the neonate are discussed.     

Treating Infections in the Newborn

Newborns with severe infections may die quickly, and physicians usually must start treatment before they confirm the diagnosis or isolate the organism. If Escherichia coli or Klebsiella infection is suspected, start aqueous penicillin G and kanamycin. If a Pseudomonas infection seems probable, use polymyxin B sulfate. The same drugs are effective against organisms causing severe pneumonias, but in staphylococcal pneumonia, intramuscular bacitracin works best.     

Infections in the heart transplant recipient

The overall incidence of infection after transplantation has decreased with improved immunosuppressive agents, increased knowledge and use of prophylaxis, and better detection and treatment of infection. Nevertheless, infection continues to be a major cause of morbidity and mortality in heart transplant recipients. The knowledgeable nurse in any setting who cares for a transplant recipient must be aware of the lifelong susceptibility to common and opportunistic infections. The transplant recipient and his or her family must also be aware of the risks of early opportunistic infection. Infection is a lifelong concern for all persons on immunosuppressant medications, and the individual must learn appropriate precautions to reduce this risk. Hand washing and avoidance of infected individuals are the most important self-care actions that the transplant patient should adopt. Recipients must also learn to monitor for subtle signs of infection. The nurse is responsible for teaching self-care to patients and family members. Ultimately, a team effort by the patient, family, nurses, and physicians can reduce the risk of infection in this vulnerable population.     

Infections in the female genital tract

Anaerobic organisms are the predominant etiologic agents in female genital tract infections. This article describes the conditions necessary for anaerobic growth, cites the diseases in which these organisms play a role, and outlines therapy for anaerobic genital infections. As interest in anaerobic bacteria has increased and culture techniques have improved, the number and variety of species of organisms has grown. Infections generally consist of several anaerobic species with 1 or more aerobic species. It is unclear whether additional organisms such as mycoplasma species or chlamydia impact on the establishment of genital tract infections, and whether multiple anaerobic organisms are needed to establish and maintain infection. For clinical infection to develop, an alteration in either host resistance or numbers of bacteria present must occur. Infections are usually associated with a compromised host whose defense mechanisms have been altered by natural causes or medical interventions such as trauma, surgery, irradiation, steroid treatment, immunosuppressive agents, cytotoxic agents, and certain antibiotics. Infections are classified as either hospital-acquired or community-acquired. The latter category includes pelvic inflammatory disease, pelvic thrombophlebitis, septic abortion, and premature rupture of the membranes. Hospital-acquired infections include postcesarean section endometritis, postoperative pelvic infections, wound infections, hospital-terminated pregnancy, septic thrombophlebitis, and pelvic abscess. Most diseases caused by anaerobic bacteria are characterized by tissue necrosis and abscess formation and an indolent or chronic course. Therapy options include supportive therapy with fluids and blood, administration of antibiotics, and surgical drainage. Initial therapy with full supportive endeavors and full-dose antimicrobial therapy is preferable to planned sequential antibiotic management. In vitro activity against anaerobes and aerobic organisms, tissue penetration, and toxicity should be considered in selecting antimicrobial agents. High-dose single agent chemotherapy is effective in early infections, whereas late infections require double or triple therapy.     

Infections in the immunocompromised rheumatologic patient

Immunocompromised patients with rheumatic diseases have an increased risk of infections. A major risk factor for infection seems to be the immunosuppressive therapy used. Newer therapies for RA may lead to increased rates of infection by opportunistic pathogens such as Mycobacteria tuberculosis. Because disease manifestation may mimic signs and symptoms of infection, prompt diagnosis may be difficult. Familiarity with the likely infections and their causes should aid in obtaining the appropriate culture specimens.     

Infections in pregnancy

Infections in pregnancy may complicate its course and harm the fetus or newborn after vertical transmission. Treatment of asymptomatic bacteriuria is mandatory in pregnant women given the high risk of secondary pyelonephritis. Intraamniotic infection usually arises by the ascending route and is associated with premature rupture of membranes. Vaginal infections promote preterm labour or premature rupture of membranes and may be transmitted to the child during labour. They must therefore be treated although they often cause little discomfort to the pregnant woman. Systemic infections due to viral, protozoal and bacterial pathogens may be transmitted transplacentally and cause embryopathies, fetopathies or neonatal infections. Depending on the responsible agent the negative impact on the course of pregnancy and on the fetus' or neonate's health can be prevented or reduced by prophylactic or therapeutic interventions.