Tags: Glycopeptides

Haemophilus, Bordetella, & Branhamella Species

Before 1990, strains of Haemophilus influenzae type b were found in the upper respiratory tract of 3-5% of children and a small percentage of adults. Colonization rates with type-b strains are even lower now, reflecting routine immunization of infants against H influenzae type b. Non-type-b encapsulated H influenzae are present in the nasopharynx of < 2% of individuals, whereas nonencapsulated (nontypable [see below]) strains colonize the respiratory tract of 40-80% of children and adults.

Enterococci

Enterococci are able to grow and survive under harsh conditions and can be found in soil, food, water, and a wide variety of animals. The major habitat of these organisms is the gastrointestinal tract of humans and other animals, where they make up a significant portion of the normal gut flora. Most enterococci isolated from human stools are E faecalis, although E faecium are also commonly found in the human gastrointestinal tract. Small numbers of enterococci are occasionally found in oropharyngeal and vaginal secretions and on the skin, especially in the perineal area.

Specific Anti-Infective Agents

Clinicians should be familiar with the general classes of antibiotics, their mechanisms of action, and their major toxicities. The differences between the specific antibiotics in each class can be subtle, often requiring the expertise of an infectious disease specialist to design the optimal anti-infective regimen. The general internist or physician-in-training should not attempt to memorize all the facts outlined here, but rather should read the pages that follow as an overview of anti-infectives. The chemistry, mechanisms of action, major toxicities, spectrum of activity, treatment indications, pharmacokinetics, dosing regimens, and cost are reviewed.

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.

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.

Chloromycetin 250mg Tablets (Chloramphenicol)

Vancomycin and teicoplanin are the only members of this class of antibiotics. Vancomycin is a high-molecular-weight glycopeptide that is bactericidal for gram-positive microorganisms. It inhibits cell-wall synthesis. Given parenterally, it is the drug of choice for methicillin-resistant staphylococcal infections.

Quinupristin and Dalfopristin

Quinupristin and dalfopristin is a combination of 2 semisynthetic streptogramin (synergistin) antibiotics that act synergistically against susceptible gram-positive bacteria.

Vancomycin Hydrochloride

Limited information is available on the acute toxicity of vancomycin. The IV LD50 of the drug in rats or mice is 319 or 400 mg/kg, respectively. Treatment of vancomycin overdosage is mainly supportive with maintenance of glomerular filtration.

Community-Acquired Pneumonia: Current Therapies

Many highly effective agents are available for the treatment of bacterial community-acquired pneumonia (community-acquired pneumonia) and other community-acquire respiratory tract infections (RTIs). Currently marketed antibiotics for community-acquired pneumonia demonstrate similar efficacy rates in clinical trials, and these agents have generally achieved clinical symptom resolution in 85-95% of trial participants.

Antibiotics and Antibiotic Resistance

Antimicrobial resistance in Streptococcus pneumoniae and other community-acquired pneumonia pathogens has progressed at an alarming rate. Approximately one-third of pneumococci exhibit reduced susceptibility to penicillin (i.e., higher MICs) that also confers reduced susceptibility to other agents in the β-lactam class of antibiotics. Macrolide resistance levels range between 23% and 30% in the United States, and much higher levels are observed in some other markets. N.