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35 Cards in this Set
- Front
- Back
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Clostridium spp.
Basic characteristics |
- Anaerobic, gram positive rod, "boxcar-shaped"
- Spore-former can survive hostile environments - Soil - natural habitat - Most rapidly growing organism (every 12 minutes) |
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Clostridium dificile
Basic Characteristics |
- Disease: nosocomial diarrhea -> pseudomembranous colitis
- Predisposing factor = antimicrobial therapy -Pathogenesis: Toxin A - enterotoxin, more important Toxin B - cytotoxin - Treatment: metronidazole p.o. |
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Clostridium dificile
Characteristics of Disease |
- Organism is obtained from hospital environment
- Gut flora is altered by antimicrobial therapy - Alteration in gut flora reduces its capacity to inhibit the growth of C. difficile - C. dificile grows and produces toxins in gut - Toxin mediates diarrhea and more severe manifestations such as non-specific and pseudomembranous colitis |
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Clostridium perfringens
Basic Characteristics |
- Disease: gas gangrene, food poisoning
- Normal bowel flora - Predisposing factor = traumatic wound, post-surgery - Virulence: histotoxic - Treatment: debridement (amputation), leave wound open to air, Pen G |
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Clostridium perfringens
Characteristics of Disease |
- Inoculation of tissue during trauma
- Tissue damage restricts blood flow and oxygenation of tissue - Organism either germinates from spores introduced into wound or vegetative organisms begin to grow in tissue - Very rapid growing organism - Gas is a metabolic by-product - Produces proteolytic and other toxins that degrade tissue - There is no pus b/c WBC’s recruited by immune response are quickly degraded |
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Clostridium botulinum
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- Disease – flaccid paralysis leading to respiratory arrest
- Three forms of disease: - Infant botulism - most common, honey/dirt ingestion, constipation, poor feeding, consume organism - Food-borne botulism - improperly canned vegetables, soups, fish (home-canned), consume toxins - Wound botulism organism in wound - Inhalational – a bioterrorism agent - Pathogenesis: neurotoxin - blocks Ach release -> flaccid paralysis -> difficulty swallowing, talking, suckling -> death by respiratory arrest - Tx: respiratory support plus antitoxin (from CDC) |
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Clostridium tetani
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- Disease: tetanus
- Predisposing factor: trauma, usually stepping on nail - Virulence: neurotoxin that blocks inhibition -> spastic paralysis -> lockjaw or "trismus" -> respiratory failure - Treatment: antitoxin, vaccine, respiratory support, pen G or metronzidazole |
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D cycloserine
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- A D-Ala analogue=
- inhibits L-Ala racemase D-Ala and also D-Ala synthetase D-Ala-D-Ala |
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Vancomycin
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- binds D-Ala-D-Ala precursor blocking polymerization
- Also injures cytoplasmic membrane |
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Bacitracin
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- blocks regeneration of C55-isoprenol phosphate carrier.
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β-lactams (penicillins, cephalosporins)
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- block transpeptidation in crosslinking side chains
- Sonly formed by growing cells, so only act on growing cells - may be sufficient to "kill" some organisms |
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Aminoglycosides
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- streptomycin, kanamycin, gentamicin, tobramycin
- bind to 30S subunit -> misreading of code, release of ribosome from mRNA - irreversible, cidal |
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Tetracyclines
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- act on 30S ribosome, inhibit aa-t-RNA binding to A site
- static, reversible |
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Macrolides
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- erythromycin, clindamycin clarithromycin, azithromycin
- act on 50S ribosome, block transfer and translocation - static, reversible |
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Oxazolidinones
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- Linezolide - for resistant enterococcal and staph
- only against gram positives - binds to 23S RNA on 50S, so no 70S - static for staphy and enterococci, - cidal for strep |
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Sulfonamides
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- antibacterials - dye derivs, not microbial products
- Inhibition (PABA) into FA b/c they are structural analogues of PABA |
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Trimethoprim
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inhibits DHT to THF
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Rifamycins
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- aromatic ring w/ long aliphatic bridge
- Rifampin binds to β subunit of RNA poly, no transcription - high rates of mutation of target site is a problem |
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Quinolones
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- interfere with gyrase α, reformation of phosphodiester bond (rejoining DNA after ds cleavage by gyrase)
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Novobiocin
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- blocks binding of ATP to gyrase/DNA complex, interfering with gyrase β - decreased DNA supercoiling
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Peptostreptococcus
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- Gram positive cocci, anaerobe
- microflora in oropharynx and intestinal tract |
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Actinomyces
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- Gram positive non-spore- forming rods - anaerobes
- oropharynx - some microaerophilic - resistant to metronidazole |
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Lactobacillus
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- Gram positive non-spore- forming rods - anaerobes
- female genital tract - vancomycin resistant |
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Propionibacterium
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- Gram positive non-spore- forming rods - anaerobes
- microflora of skin - common contaminant of CSF and blood cultures |
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bacteriods
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- Gram negative rods, anaerobes
- oropharynx and GI - in female genital tract - the most common isolated in human infections - most produce beta-lactamse - treated with a beta-lactam /beta lactamase inhibitor such as the combination of ampicillin and sulbactam or metronidazole. |
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Porphyromonas
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- Gram negative rods - anaerobes
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Prevotella
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- Gram negative rods - anaerobes
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Fusobacterium
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- Gram negative rods - anaerobes
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Brain abscess
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Prevotella, Porphyromonas, and Peptostreptococcus
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Device related meningitis
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Propionibacterium
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Deep fascial space infections
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Bacteroides, Prevotella, Porphyromonas, Peptostreptococcus, and Fusobacterium
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Lung abscess
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Bacteroides, Prevotella, Porphyromonas, Fusobacterium, and Peptostreptococcus
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Peritonitis
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Bacteroides fragilis
Escherichia coli Peptostreptococcus Prevotella |
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Female genital tract infections
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Peptostreptococcus, Prevotella, and Porphyromonas
B. fragilis if abscess |
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Foot infections
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Bacteroides and Peptostreptococcus
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