Clinical presentation varies with age, and generally, the younger the patient, the more atypical and the less pronounced is the clinical picture.
Author: Brian Holtry
Antimicrobial Regimen Selection
A generally accepted systematic approach to the selection and evaluation of an antimicrobial regimen is shown in Table Systematic Approach for Selection of Antimicrobials. An «empiric» antimicrobial regimen is begun before the offending organism is identified, while a «definitive» regimen is instituted when the causative organism is known. The use of combinations to prevent the emergence of resistance is widely applied but not often realized. The only circumstance where this has been clearly effective is in the treatment of tuberculosis.
Infectious disorders
Infectious diseases comprise those illnesses that are caused by microorganisms or their products. Clinical manifestations of infection occur only when sufficient tissue injury has been inflicted directly by microbial products (e.g., endotoxins and exotoxins), or indirectly by host responses (e.g., cytokines and hydrolytic enzymes released by polymorphonuclear leukocytes). Despite the extraordinary recent advances that have occurred in therapeutics for infectious diseases, a number of basic principles should be followed to prescribe antimicrobials and vaccines is an optimal manner.
Epidemiologic and virulence factors in infectious diseases
Before appropriate therapy can be given for an infectious disease, consideration of epidemiologic factors is essential. This section does not fully discuss the epidemiology (the determinants, occurrence, distribution, and control of health and disease) of infectious diseases. However, a number of basic principles and historical points are worth emphasizing.
Antimicrobial therapy: general principles
A wide variety of antimicrobial agents is available to treat established infections caused by bacteria, fungi, viruses, or parasites. This section will cover the general principles of antimicrobial therapy and will also include illustrative clinical problems to emphasize proper decision-making in using antimicrobials.
Toxicity of Antimicrobial Therapy
The mechanisms associated with common adverse reactions to antimicrobials include dose-related toxicity that occurs in a certain fraction of patients when a critical plasma concentration or total dose is exceeded, and toxicity that is unpredictable and mediated through allergic or idiosyncratic mechanisms. For example, certain classes of drugs such as the aminoglycosides are associated with dose-related toxicity.
Nucleoside analogs
Nucleoside analog reverse transcriptase inhibitors have formed the backbone of anti-human immunodeficiency virus therapy for the last decade (see Table Characteristics of Nucleoside Reverse Transcriptase Inhibitors). Reverse transcription is necessary for human immunodeficiency virus RNA to be used as a template to produce viral DNA, which can be integrated into the cellular genome.
Management of Bacterial Meningitis
Meningitis used to be a disease that occurred primarily in children younger than 12 years. The advent of a vaccine for Haemophilus influenzae has led to a marked change in the epidemiology of meningitis in developed countries.
Management of Infective Endocarditis
Infective endocarditis is a microbial infection of the endothelial lining of the heart. The characteristic lesion is a vegetation (a mass comprised of fibrin, platelets, microorganisms and their product or products on a valve leaflet). Multiple valves may be involved, as may any part of the endothelium of the heart.
Management of Tuberculosis
Tuberculosis was a disappearing disease in North America until the early 1980s. However, the spread of human immunodeficiency virus infection has changed that. From 1985 to 1992 there was an increase in the number of cases of tuberculosis reported in the United States, and most of these cases were in New York, New Jersey, Texas, Florida, and California. The other major change in the epidemiology of tuberculosis has been the emergence of multidrug-resistant disease.