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162 Cards in this Set
- Front
- Back
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What is special about first generation cephalosporins?
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Gram-positive cocci; soft tissue and skin infections; staphylococci, pneumococci, and streptococci
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What are three, first generation cephalosporins?
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Cefazolin, Cephalexin, Cefadroxil; all have an "a" after the cef(ph)
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What is special about second generation cephalosporins?
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Aerobic gram-negative and some gram-positive sensitive to 1st generation cephalosporins
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What species do second generation cephalosporins work well on?
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Haemophilus influenza and Bacteroides fragilis
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Name three second generation cephalosporins.
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Cefuroxime, Cefoxitin, and Cefotetan (mainly "fox" "roxs")
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What is special about third generation cephalosporins?
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Expanded aerobic gram-negative spectrum; can cross BBB
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Name three, third generation cephalosporins.
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Cefotaxime, Ceftazidime, and Ceftriaxone; mainly "tax" and "tri"
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What is special about fourth generation cephalosporins?
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Similar to third generation, but more resistant to beta-lactamases; (Cefepime)
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What does sulfonamides resemble, what process does it inhibit, and what is it administered with?
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p-aminobenzoic acid (PABA); folate synthesis; Trimethoprim (combination is called SMX-TMP, Bactrim, Septra)
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Primary virulence factors of Bacillus anthracis.
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Capsular polypeptide (poly-D-glutamate) and anthrax toxin (protective factor, edema factor (adenylate cyclase), and lethal factor
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Biochemistry of Bacillus anthracis
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facultative anaerobe, Gram (+) rod, central spore, non-motile
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Which bacterium is associated with intoxicated fried rice, and how does it cause sickness?
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Bacillus cereus; consumption of inactivated heat-labile toxin (diarrhea) and active heat-stable "puke" toxin
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Which bacterium causes ecthyma gangrenosum?
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Pseudomonas aeruginosa
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Which bacterium is associated with a farmer getting fever, adenopathy, and a black eschar lesion with surrounding edema?
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cutaneous Bacillus anthracis
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What happens to Bacillus anthracis spores after they enter the body?
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They are taken up by macrophages, where the edema and lethal factors allow the spores to survive killing and subsequently germinate
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Does inhalation anthrax spread to the blood?
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Yes, you actually culture the blood for the organism.
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What is a causative agent of furuncles?
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Staphylococcus spp.
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What special enzyme does Bacillus anthracis/cereus contain that allow it to for a white precipitate on egg yolk agar?
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Lecithinase
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Is Bacillus hemolytic?
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No (gamma hemolysis)
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What is the use for India Ink, and what is a species that it can be used on?
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Visualizes capsules; Bacillus anthracis, Clostridium perfringens
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What is a stain that allows you to visualize a spore?
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Malachite green stain
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What is the antibiotic treatment for cutaneous anthrax?
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Ciprofloxacin (quinolones) for 7-10 days
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What bacterium is associated with severe diverticulitis and a perforated colon?
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Bacteroides fragilis
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Biochemistry of Bacteroides fragilis
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anaerobe, Gram (-) rod, some are encapsulated
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What is the most common cause of intraabdominal infection
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Bacteroides fragilis
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What is the special agar that Bacteroides fragilis must be grown on?
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BBE agar (Bacteroides bile esculin); colonies appear black
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What is the purpose of Bacteroides fragilis's polysaccharide capsule?
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Allows bacterium to inhibit phagocytosis and adhere to peritoneal surface
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What product does Bacteroides fragilis produce that inhibits phagocytosis?
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Succinic acid
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How potent is the endotoxin from Bacteroides fragilis?
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Little biological activity (allows you to administer bacterocidal antibiotics without worry of septic shock)
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What bacterium has an endotoxin of little biological importance?
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Bacteroides fragilis
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Name an anaerobic bacterium that can SURVIVE in the presence of small amounts of oxygen. What enzyme allows it to do so?
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Bacteroides fragilis; superoxide dismutase
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What type of bacterial infection is associated with a foul smelling wound?
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Infection by anaerobic bacteria (e.g. Bacteroides)
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Name a bacterium that is resistant to kanamycin, colistin, and vancomycin
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Bacteroides fragilis
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What is suggested to care for a Bacteroides fragilis infection?
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Surgical debridement and metronidazole/imipenem
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Is Actinomyces Gram (+)/(-), aerobe/anaerobe/facultative anaerobe/microaerophilic?
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Strict anaerobe, Gram (+)
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Name an aerobic, Gram (-) bacterium associated with Bacteroides fragilis mixed infections.
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Neisseria gonorrhoeae
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Name the bacterium associated with camping trips, achiness, fatique, circular red rashes with some central clearing.
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Borrelia burgdorferi
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Which bacterium is associated with erythema migrans?
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Borrelia burgdorferi
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What are the two primary vectors for the causative agent of erythema migrans?
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Ixodes ticks and white-footed mice
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Which bacterium is associated with arthritis 1-4 weeks postinfection?
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Borrelia burgdorferi
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What is the most common vector-born disease in the US?
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Lyme disease (Borrelia burgdorferi)
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Name three genera of spirochetes?
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Leptospira, Borrelia (Lyme disease), and Treponema (syphilis)
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What is the antibiotic treatment for syphilis?
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Penicillin
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What is the antibiotic treatment for early Lyme disease?
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Doxycycline and amoxicillin
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How does the causative agent for Lyme disease move, and why doesn't this device stimulate an immune response?
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Endoflagella found between the two layered outer cell membrane
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Would Borrelia burgdorferi survive in a strictly anaerobic environment?
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No, it is microaerophilic (needs very little oxygen, with lots of carbon dioxide)
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What region of the US is associated with a higher incidence of Lyme disease, and during what period of the year is the incidence highest?
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New England area; May-July (when nymph stage of Ixodes ticks are most prevalent)
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What is a significant virulence factor of B. burgdorferi?
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Outer surface proteins (Osp); used to make a vaccine
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Which microaerophilic bacterium grows best at 42 degrees Celsius?
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Campylobacter jejuni
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What is the most common cause of bacterial food poisoning?
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Campylobacter jejuni (~70%)
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Which form of E. coli infection is similar to Campylobacter jejuni food poisoning?
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Enterohemorrhagic E. coli (EHEC) with its Shiga-like toxin
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How long after eating an undercooked, contaminated chicken dinner would you expect to start experiencing symptoms, and what would those symptoms be?
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1-3 days; fever, malaise, abdominal pain, bloody diarrhea, mucosal inflammation, and bacteremia
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What is the most common treatment for uncomplicated C. jejuni food poisoning?
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liquid replacement for up to 7 days
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What is a potential sequelae of Campylobacter gastroenteritis?
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Guillain-Barre syndrome (similarity between LPS and myelin proteins)
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What is the causative agent for bacteremia, septic arthritis, peritonitis, abscesses, meningitis, and endocarditis in an immunocompromised patient?
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Campylobacter fetus
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What is the difference between growth environments between C. jejuni and C. fetus?
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C. jejuni prefers 42 degrees Celsius whereas C. fetus prefers 25 degrees Celsius
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Is C. jejuni a motile bacterium?
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Yes (flagellum)
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Would C. jejuni survive in open air? How about in an anaerobic environment?
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No. No. It is a microaerophile.
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What is the differential diagnosis of acute gastroenteritis?
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Salmonella, Shigella, Yersinia, Campylobacter, and Escherichia
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Name an oxidase positive, comma-shaped, Gram (-) bacterium.
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Campylobacter jejuni
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What is the antibiotic choice for complicated Campylobacter jejuni gastroenteritis?
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Erythromycin
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Name two bacteria who's primary antibiotic treatment is erythromycin.
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C. jejuni and Chlamydia trachomatis
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Name two bacteria associated with ingesting unpasteurized milk.
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C. jejuni and Brucella spp.
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Name two bacteria that are comma-shaped.
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Campylobacter spp. and Vibrio cholerae
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Which bacterium is associated with cervical motion tenderness?
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Chlamydia trachomatis
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What is the infectious and replicative stages of C. trachomatis?
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elementary body and reticulate body
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What is the most common sexually transmitted disease in the US?
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Chlamydia
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What is a common disease associated with Chlamydial infections?
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Gonorrhea (Neisseria gonorrheae)
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What is the Chandelier sign?
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Cervical motion tenderness associated with Chlamydia trachomatis.
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Name a gram-negative obligate intracellular parasite.
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Chlamydia trachomatis (elementary and reticulate body)
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How thick is the peptidoglycan layer of C. trachomatis?
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It doesn't have one, and it also lacks muramic acid (unique)
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What are the primary symptoms of Chlamydial infections?
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Cervicitis (women), epididymitis (men), conjunctivitis (neonatal infection), PID
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What is one of the most common preventable cause of blindness in the world?
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Ocular trachoma caused by Chlamydia
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What is Lymphogranuloma venereum? What is the causative agent?
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Painful papule on genitalia that heals spontaneously, followed by regional lymph node localization for two months. The lymph nodes swell, and may rupture to expel the exudate. It is caused by Chlamydia trachomatis.
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What do Chlamydophila pneumonia and psittaci have in common?
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They are both causative agents for atypical pneumonia.
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Which antibiotic is used to treat ocular Chlamydia?
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Tetracycline
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Which antibiotic is used to treat Chlamydial cervicitis and urethritis?
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Azithromycin
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Which bacterium is the causative agent of gastroenteritis following a course of antibiotics (e.g. amoxicillin/clavulanate)?
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Clostridium difficile
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Which bacterium is the causative agent of pseudomembranous colitis?
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Clostridium difficile
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What is the most common Clostridium species isolated from human infections, which is also associated with gas gangrene?
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Clostridium difficile
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Name three species of Clostridium, and name their corresponding disease.
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tetani (tetanus), botulinum (botulism), and difficile (antibiotic gastroenteritis and pseudomembranous colitis)
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What are the symptoms associated with ingesting tainted canned vegetables, and what is the causative agent?
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nausea, blurred vision, and weakness of the upper extremities spreading downward within 12-36 hours after ingestion of the toxin. Clostridium botulinum.
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What are the two toxins associated with Clostridium difficile infection, and what is their purpose?
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Toxin A (enterotoxin) and the more biologically active Toxin B (cytotoxin)
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What constituent of endospores offers stability?
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Calcium-dipocolinate complex
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What is the gold standard for laboratory diagnosis of diarrhea caused by C. difficile?
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Toxin detection from the stool using a tissue culture assay.
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What is the treatment of choice for Clostridium difficile infection?
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Metronidazole, with vancomycin reserved for those who fail first-line treatment (due to endospore).
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Pseudomembraneous colitis following broad-spectrum antibiotic administration most likely occurs due to what?
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Toxin A and B
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What is the causative agent for a gray membrane coating of the tonsil, which extends over the uvula and soft palate?
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Corynebacterium diphtheriae
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What is the characteristic shape and arrangement of Corynebacterium diphtheriae?
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Club-shaped; Chinese lettering
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What factor is required for the expression of diphtheria toxin?
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Lysogenic bacteriophage (beta-phage)
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Where in the body is C. diphtheriae a normal flora?
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Respiratory tract
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If a strain of non-virulent C. diphtheriae infects the nasal mucosa of an individual, what will be the symptoms?
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Runny nose, watery eyes, sneezing, coughing, but NO FEVER AND NO PSEUDOMEMBRANE (toxin not released systemically)
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What characteristic term is associated with individuals infected with a virulent strain of C. diphtheriae?
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Bull neck due to lymphadenopathy and pseudomembrane
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What are three main signs of infection with a virulent strain of C. diphtheriae?
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Pseudomembrane, Bull neck, and bacteremia
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What is the Elek Test?
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immunodiffusion test to detect the production of diphtheria toxin in a strain of C. diphtheriae.
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What composes the capsule of Corynebacterium diphtheriae, and how fast does it move?
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It doesn't have a capsule and it is non-motile.
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What is the composition of, and the mode of action of the Diphtheria toxin?
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An A-B exotoxin; "B" binds, and "A" is released where it inhibits protein synthesis by ADP-ribosylation of EF-2
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What type of agar is C. diphtheriae plated on?
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Tellurite agar (appears as black colonies)
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What is the curative method of choice for Corynebacterium diphtheriae?
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Erythromycin and antitoxin; vaccination with TDaP
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Name a Gram (+) cocci associated with indwelling Foley catheters.
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Enterococcus faecalis
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Name three Gram (+) cocci.
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Enterococcus faecalis, Staphylococcus aureus, and Streptococcus pyogenes
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Does E. faecalis cause community-acquired or nosocomial UTI's more often?
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It causes both, but usually nosocomial due to indwelling Foley catheters
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What are two other complications of E. faecalis infection?
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Bacteremia and endocarditis (mitral valve usually)
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What is the oxygen-demand category for the Gram (+) cocci, Enterococcus faecalis?
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Aerobe
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Since E. faecalis is a normal fecal flora, what types of environmental factors can it withstand?
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high pH, [bile salts], and saline concentrations up to 6.5 percent (similar to S. aureus)
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What Lancefield antigen group does Enterococcus faecalis belong to?
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Group D streptococcal carbohydrate antigen
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Is E. faecalis a fairly resistant bacterium?
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Yes, it has intrinsic resistance to ampicillin, penicillin, aminoglycosides, vancomycin (sometimes), etc.
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How does E. faecalis confer antibiotic resistance?
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DNA mutation, plasmid or transposon acquisition
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What is the main difference between E. faecalis and E. faecium?
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E. faecium is more resistant to antibiotics.
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What is the first line of antibiotic defense towards uncomplicated E. faecalis UTIs? Complicated cases?
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Ampicillin; ampicillin or vancomycin plus aminoglycoside
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What Lancefield antigen type is Streptococcus agalactiae?
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Group B for Baby (neonatal meningitis)
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What Lancefield antigen type is Streptococcus pneumoniae?
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It doesn't have a Lancefield antigen type
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What is the most commonly found aerobic (facultative anaerobe), Gram (-) bacilli in the GI tract of humans?
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Escherichia coli
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Which bacterium is associated with 80% of UTIs?
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Escherichia coli
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Where is the likely source of diarrheal E. coli infection versus UTI infection?
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Diarrheal infection is acquired from the environment, whereas other types of E. coli infection come from endogenous sources
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What are the four serotypes associated with E. coli infections?
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Enterotoxigenic, enterohemorrhagic, enteroaggregative, and enteroinvasive
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Which E. coli serotype is associated with enterohemorrhagic E. coli?
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O157:H7 (hemolytic anemia, thrombocytopenia, and renal failure)
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What structural feature of certain strains of E. coli allow them to cause a UTI?
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adhesions (pili)
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Biochemistry of E. coli
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Glucose and lactose fermenters, oxidase negative, Gram (-) rods, reduce nitrates to nitirites
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What is the fermenting difference between Neisseria menigitidis and Neisseria gonorrhoeae
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The first ferments both maltose and glucose, whereas the second ferments glucose only!
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Which virulence factor produced by E. coli is important in producing an inflammatory response in the urinary tract?
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Hemolysin HlyA
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What are the three antigen types found on E. coli?
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O (LPS), K (capsule), and H (flagella)
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What are two symptoms of pyelonephritis and what is the most common bacterial causative agent?
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Fever and flank pain; E. coli
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What would E. coli plated on MacConkey agar look like
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Pink colonies (lactose fermenter, in addition to glucose fermenter)
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What is the antibiotic of choice for E. coli UTIs?
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trimethoprim, sulfamethoxazole (SMX-TMP), or fluoroquinolone
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Which toxin type does EHEC verotoxin resemble? Is the diarrhea bloody?
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Shiga-like toxin. Yes (Enterohemorrhagic E. coli)
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Name the food vector associated with the following bacterial food "poisonings": Shigella, Salmonella, E. coli, Campylobacter, and Vibrio.
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Shigella (general fecal-oral route), Salmonella (fecal matter on eggs), Escherichia (undercooked beef), Campylobacter (undercooked chicken), and Vibrio (seafood)
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Is E. coli indole positive or negative?
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Positive
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Is E. coli oxidase positive or negative?
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Negative
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What is the flagellar arrangement for E. coli?
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Peritrichous
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What is the oxygen-demand environment for H. pylori? Name another Gram (-) bacterium that has this same requirement.
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Microaerophilic; Campylobacter jejuni
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Is H. pylori motile?
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Yes, it has polar flagella that allow a corkscrew-like motion
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What two factors allow Helicobacter pylori to colonize the stomach?
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Bacterial acid-inhibitory protein and urease activity (produces ammonia to neutralize the stomach acid)
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HPV is to cervical cancer as H. pylori is to what?
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gastric and duodenal ulcers
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Is H. pylori oxidase +/-, catalase +/-, mucinase +/-?
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All positive
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What is the animal reservoir for H. pylori?
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Humans are the only carriers (fecal-oral, oral-oral, or contaminated water/food)
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What is the most common diagnostic test for H. pylori infection?
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Urea breath test
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What is the curative method for H. pylori infection?
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PPI, antibiotic, and bismuth
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What was the most common cause of pediatric meningitis before introduction of routine childhood immunization against this bacterium?
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Haemophilus influenzae
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What feature of H. influenzae allow it to adhere to respiratory mucosal membranes and evade phagocytosis?
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capsule
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What are two potential complications associated with H. influenzae infections in young children?
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Epiglottitis and bacterial meningitis
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What signs/symptoms does Haemophilus ducreyi cause?
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The STD chancroid (genital skin lesions and lymphadenopathy, leading to abscess formation if untreated)
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What is the oxygen-demand status of H. influenzae?
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Facultative anaerobe
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What sort of growth factors are required on nutrient agar for H. influenzae?
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X factor (hematin) and V factor (NAD) on Chocolate agar
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What constituent of the capsule of H. influenzae makes it unique?
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Polyribitol phosphate (PRP)
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What is the target of antibodies made against the H. influenzae capsule vaccine?
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purified PRP antigents (Polyribitol phosphate)
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What characteristic of CSF distinguishes septic from aseptic meningitis?
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Septic (bacterial) meningitis has elevated PMNs, elevated protein, and decreased glucose
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What is the shape of Haemophilus influenzae?
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Coccobacilli
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What is the treatment of choice for H. influenzae?
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Third generation cephalosporin (cefotaxime, ceftriaxone), amoxicillin-clavulanate, or a macrolide
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What is the causative agent for Chancroid and what is the treatment for it?
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Haemophilus ducreyi; erythromycin or fluoroquinolone
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What is a virulence factor of H. influenzae that allows it to invade the respiratory lining?
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IgA protease
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What chemical component in the CSF is being detected with a rapid latex agglutination test against Haemophilus influenzae?
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polysaccharide capsule
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Is Haemophilus influenzae hemolysis negative or positive?
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Negative
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Why are third generation cephalosporins the antibiotic treatment of choice against H. influenzae?
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These antibiotics (cefotaxime, ceftriaxone) penetrate the BBB.
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What virulence factor of S. aureus allows it to avoid phagocytosis? What specific component does it bind?
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Protein A binds the Fc component of mainly IgG
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What two bacteria are associated with Impetigo?
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S. aureus and S. pyogenes
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Name a new penicillinase Beta-lactam used for S. aureus infections before Vancomycin.
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Oxacillin
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Name two coagulase negative Staphylococci.
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S. epidermidis (catheters) and S. saprophyticus (sexually active young females)
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Which bacterium possess M protein, and what is its function?
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S. pyogenes; binds serum factor H, destroying C3 convertase to prevent opsonization by C3b (antiphagocytic)
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What causes rheumatic fever?
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When the host organism creates anti-M protein AB that crossreact with heart muscle. Caused by S. pyogenes infection
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Do group A streptococci (S. pyogenes) have a capsule? group B (S. agalactiae)?
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Yes; No
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What is erysipelas? What is it caused by (bacterium)?
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It is a dermal skin infection caused by Streptococci, leading to a warm, red, hardened lesion on the skin.
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