Tags: Quinupristin

Enterococci

Essentials of Diagnosis • Gram stain shows gram-positive cocci that occur in singles, pairs, and short chains; recovery of microorganism from culture of blood or other sterile source. • Lancefield group D antigen. • Clinical isolates: Enterococcus faecalis, 74%; E faecium, 16%; other species, 10%. • Facultative anaerobes grow in 6.5% NaCl at pH 9.6 and at temperatures ranging from 10 °C to 45 °C, and grow in the presence of 40% bile salts and hydrolyze esculin and L-pyrrolidonyl-ß-naphthylamide. • Infections typically of a gastrointestinal or genitourinary origin. • The most common infections are urinary tract infection, bacteremia, endocarditis, intra-abdominal and pelvic infection, and wound and soft tissue infection. General Considerations …

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Enterococci: Clinical Syndromes

URINARY TRACT INFECTION Urinary tract infections, including uncomplicated cystitis, pyelonephritis, prostatitis, and perinephric abscess, are the most common type of clinical infections produced by enterococci (Box 1). Most enterococcal urinary tract infections are nosocomial and are associated with urinary catheterization or instrumentation. BACTEREMIA & ENDOCARDITIS Nosocomial enterococcal bacteremias are commonly polymicrobial. Portals of entry for enterococcal bacteremia include the urinary tract, intra-abdominal or pelvic sources, wounds (especially burns, decubitus ulcers, and diabetic foot infections), intravascular catheters, and the biliary tree. Metastatic infections other than endocarditis are rare in enterococcal bacteremia. Enterococci account for ~5-10% of all cases of infective endocarditis (see site). Most cases are caused by E faecalis, but E …

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Anti-Infective Agent Dosing

The characteristics that need to be considered when administering antibiotics include absorption (when dealing with oral antibiotics), volume of distribution, metabolism, and excretion. These factors determine the dose of each drug and the time interval of administration. To effectively clear a bacterial infection, serum levels of the antibiotic need to be maintained above the minimum inhibitory concentration for a significant period. For each pathogen, the minimum inhibitory concentration is determined by serially diluting the antibiotic into liquid medium containing 104 bacteria per millihter. Inoculated tubes are incubated overnight until broth without added antibiotic has become cloudy or turbid as a result of bacterial growth. The lowest concentration of antibiotic that prevents …

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Specific Anti-Infective Agents

Antibiotics Before prescribing a specific antibiotic, clinicians should be able to answer these questions: •  How does the antibiotic kill or inhibit bacterial growth? •  What are the antibiotic’s toxicities and how should they be monitored? •  How is the drug metabolized, and what are the dosing recommendations? Does the dosing schedule need to be modified in patients with renal dysfunction? •  What are the indications for using each specific antibiotic? •  How broad is the antibiotic’s antimicrobial spectrum? •  How much does the antibiotic cost? 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 …

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Skin and Soft Tissue Infections

Definition Bacterial infections of the skin can be classified as primary (pyodermas or cellulitis) or secondary (invasion of the wound) (Table Bacterial Classification of Important Skin and Soft Tissue Infections). Primary bacterial infections are usually caused by a single bacterial species and involve areas of generally healthy skin (e.g., impetigo, erysipelas). Secondary infections, however, develop in areas of previously damaged skin and are frequently polymicrobic in nature. The conditions that may predispose a patient to the development of skin and soft tissue infections include (1) a high concentration of bacteria, (2) excessive moisture of the skin, (3) inadequate blood supply, (4) availability of bacterial nutrients, and (5) damage to the corneal …

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Central Nervous System Infections

Definition Central nervous system infections include a wide variety of clinical conditions and etiologies: meningitis, meningoencephalitis, encephalitis, brain and meningeal abscesses, and shunt infections. The focus of this chapter is meningitis. Pathophysiology Infections are the result of hematogenous spread from a primary infection site, seeding from a parameningeal focus, reactivation from a latent site, trauma, or congenital defects in the central nervous system. central nervous system infections may be caused by a variety of bacteria, fungi, viruses, and parasites. The most common causes of bacterial meningitis include Streptococcus pneumoniae, Neisseria meningitides, Listeria monocytogenes, and Haemophilus influenzae. The critical first step in the acquisition of acute bacterial meningitis is nasopharyngeal colonization of …

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Antimicrobial Regimen Selection

Introduction 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. Confirming the presence of infection Fever Fever is defined as a controlled elevation of body temperature above the normal range of 36.7 to 37.0В°C. Fever is a manifestation of many disease states other than infection. Many drugs have been identified as causes of fever. Drug-induced fever is defined as persistent fever in the absence of infection or other underlying condition. The fever …

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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. Determinants of Antimicrobial Efficacy Measurement of antimicrobial activity in vitro Susceptibility testing is indicated for any bacterial pathogen warranting chemotherapy. Drugs that irreversibly destroy the ability of an organism to replicate, and perhaps in the process destroy the structural integrity of the organism, are microbicidal. Drugs that reversibly impair replicating ability, with this function being restored when drug concentrations fall below critical inhibitory levels, are microbiostatic. In quantitative …

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Quinupristin and Dalfopristin

C53H67N9O10S • Quinupristin and dalfopristin is a combination of 2 semisynthetic streptogramin (synergistin) antibiotics that act synergistically against susceptible gram-positive bacteria. Uses • Vancomycin-resistant Enterococcus faecium Infections Quinupristin and dalfopristin is used IV in adults for the treatment of serious or life-threatening infections caused by susceptible strains of vancomycin-resistant Enterococcus faecium (VREF), including infections associated with VREF bacteremia. Quinupristin and dalfopristin became commercially available in the US for this indication under the principles and procedures of FDA’s accelerated review process that allows approval based on analysis of surrogate markers of response (i.e., clearance of bacteremia), rather than clinical end points such as cure of infection or survival.Controlled clinical studies are underway …

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Quinupristin and Dalfopristin: Dosage and Administration

• General • Reconstitution and Administration Quinupristin and dalfopristin is administered by IV infusion over 60 minutes. Quinupristin and dalfopristin powder for injection must be reconstituted and diluted prior to administration. The manufacturer states that only 5% dextrose injection or sterile water for injection should be used to reconstitute the powder, and further dilution should be with 5% dextrose. Strict aseptic technique must be observed since the drug contains no preservative. Vials labeled as containing 500 mg (150 mg of quinupristin and 350 mg of dalfopristin) should be reconstituted by slowly adding 5 mL of one of these diluents to provide a solution containing 100 mg/mL. The vial should be gently …

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