Tags: Dicloxacillin

Actinomyces

Essentials of Diagnosis “Sulfur granules” in specimens and sinus tract drainage: hard, irregularly shaped, yellow particles measuring from 1 to 5 mm in size Gram-positive branching filaments arranged in ray-like projections under the microscope Colonies with characteristic “molar tooth” appearance Production of extensive fibrosis with “woody” induration No specific antibody or antigen detection tests General Considerations A. Epidemiology. The Actinomyces species are facultative anaerobes that commonly inhabit the oral cavity, the gastrointestinal tract, and the female genital tract, where they exist as commensals. Diversity within this genus is broad, which has led to taxonomic revision and reclassification of some species as members of the Arcanobacterium genus, eg, Actinomyces pyogenes. Disease occurs …

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Streptococcus Pyogenes

Essentials of Diagnosis • Pharyngitis: presence of sore throat, submandibular adenopathy, fever, pharyngeal erythema, exudates. • Rheumatic fever: migratory arthritis, carditis, Syndenham’s chorea, pharyngitis. • Cellulitis: pink skin, fever, tenderness, swelling. • Scarlet fever: sandpaper-like erythema, strawberry tongue, streptococcal pharyngitis or skin infection, high fever. • Post-streptococcal glomerulonephritis: acute glomerulonephritis (hematuria, proteinuria) following pharyngitis or impetigo. • Impetigo: dry, crusted lesions of the skin, weeping golden-colored fluid. • Erysipelas: salmon red rash of face or extremity, well-demarcated border, fever, occasionally bullous lesions. • Streptococcal toxic shock syndrome: isolation of Group A streptococcus from a normally sterile site, sudden onset of shock and organ failure. • Necrotizing fasciitis, myonecrosis: deep, severe pain, …

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Staphylococci

STAPHYLOCOCCUS AUREUS Essentials of Diagnosis • Large gram-positive cocci (0.7-1.5 um in size). • Colonies surrounded by zone of hemolysis on blood agar. • Colonies pigmented pale yellow to deep orange macroscopically. • Cluster in grapelike bunches microscopically. • Biochemically differentiated from streptococci by presence of the enzyme catalase. • Biochemically differentiated from other staphylococci by presence of the enzyme coagulase. • Analysis of chromosomal DNA can identify clonal isolates (useful in epidemiologic studies). General Considerations A. Epidemiology. Staphylococcus aureus colonizes the human skin, vagina, nasopharynx, and gastrointestinal tract. Colonization occurs shortly after birth and may be either transient or persistent. Published studies differ widely in estimates of the prevalence of …

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Penicillins: Drug Administration

Drug formulations Embolictoxic reactions to penicillin depot formulations were first described in patients with syphilis. The symptoms include fear of death, confusion, acoustic and visual hallucinations, and possibly palpitation, tachycardia, and cyanosis. Generalized seizures or twitching of the limbs have been observed in children and adults. As a rule, the symptoms abate and disappear within several minutes to an hour. They rarely persist for up to 24 hours. If a cardiovascular reaction with a fall in blood pressure occurs simultaneously with typical symptoms, a combination with anaphylactic shock must be considered. Such reactions have been called “pseudo-anaphylactic reactions” or “acute non-allergic reactions”, “panic attack syndrome,” and “acute psychotic reactions”. In several …

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Penicillins: Organs and Systems

Respiratory Bronchospasm may be a consequence of penicillin allergy. Acute severe dyspnea with cyanosis has also been observed without symptoms of bronchial obstruction or pulmonary edema. Specific mechanisms for such cases have yet to be identified. Allergic pneumonitis and transient eosinophilic pulmonary infiltrate (Loeffler’s syndrome) are rare. These syndromes have also been observed with penicillin hypersensitivity. In one case, an alveolar allergic reaction, probably due to ampicillin, showed features of an adult respiratory distress syndrome. Nervous system High doses of penicillins, in the order of several million units/day of penicillin G, can produce myoclonic jerks, hyper-reflexia, seizures, or coma. Drowsiness and hallucinations can occur occasionally. Such reactions are due to a …

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Penicillins: Organs and Systems: Liver

Penicillin-induced hepatotoxicity may not be as uncommon as has been thought. There have been three reviews. The first was a comparison of the assessment of drug-induced liver injury obtained by two different methods, the Council for International Organizations of Medical Sciences (CIOMS) scale and the Maria & Victorino (M&V) clinical scale. Three independent experts evaluated 215 cases of hepatotoxicity reported using a structured reporting form. There was absolute agreement between the two scales in 18% of cases, but there was no agreement in cases of fulminant hepatitis or death. The authors concluded that the CIOMS instrument is more likely to lead to a conclusion compatible with the specialist’s empirical approach. In …

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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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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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Toxicity of Antimicrobial Therapy

Mechanisms of toxicity 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. In contrast, the major toxicity of the penicillins and cephalosporins is due to allergic reactions. These differences are explained in part by the relative ability of specific drugs to inhibit enzymatic pathways in the host versus their stimulation of specific immune response. Not included in these lists is mention of the …

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