Term
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Definition
Non-motile, Non-spore-forming
Obligate aerobes
Slender bacilli
Unusual cell walls: contain mycolic acid, high lipid content - renders them hydrophobic and highly resistant to drying/disinfectants/pH changes
Slow growing with fastidious growth requirements (supplement agar with homogenized eggs and other complex media - Lowenstein-Jensen Agar); heat-sensitive (kill with pasteurization)
Stain with special dyes (Kinyoun and Auromine O) - acid fast ("red snappers")
Broken into groups - tuberculous group and Runyon groups 1-4 |
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Term
| Tuberculous Mycobacteria (M. tuberculosis, M. bovis, M. africanum) |
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Definition
All cause tuberculosis; acquired via inhalation of droplet nuclei (or through GI tract or abraded skin)
M. tuberculosis: organisms enter respiratory tract in droplets and are phagocytized by alveolar macrophages; then prevents fusion of phagosome with lysosome -> macrophages/lymphocytes attracted by chemotactic factors -> multinucleated giant cells (Langhans cells) -> granulomas to prevent disease spread
M. tb = most common cause of infection in HIV patients |
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Term
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Definition
Screen for TB with PPD and Quantiferon-TB Gold assay
Primary disease - pulmonary tract, insidious onset with nonspecific complaints, sputum production
May remain dormant in 90%
See evidence on CXR (upper lobes), positive PPD, lab detection by smear/culture(red snappers)/PCR
Screen for MDR genes with PCR
Treat with triple therapy for pulmonary disease - rifampin, isoniazid, pyrazinamide (6 months)
Skin converters - INH and PZA (9-12 months)
Prevention: N95 mask, negative pressure room with airborne precautions (consider pt non-infectious after 3 consecutive days of negative sputum samples) |
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Term
| Mycobacterium avium complex (MAC) |
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Definition
M. avium + M. intracellulare
Environmental organism (water, plants, soil)
Causes pulmonary disease in immunocompetent and immunocompromised (i.e. HIV) patients |
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Term
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Definition
| Causes fish tank granulomas |
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Term
Mycobacterium fortuitum
Mycobacterium chelonae
Mycobacterium abscessus |
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Definition
Rapid growers
Associated with cutaneous and subcutaneous infections, and prosthetic device/indwelling catheter infections |
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Term
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Definition
Cannot grow unless in an animal model
2 presentations: tuberculoid leprosy (skin hypopigmentation; in immunocompetent hosts), and lepromatous leprosy (immunocompromised; presents as nodular disfigurement of skin)
Transmitted via direct contact
Detect organisms in skin scrapings (best from earlobe)
Treatment: simple and inexpensive - sulfa drug dapsone |
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Term
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Definition
Hybrid organism: gram + and mycobacterium properties (can stain gram + or partially acid fast)
Produces long, branching, thin filaments (has a pink, beaded appearance)
Found in the soil - causes pulmonary infection from inhalation or infection through abraded skin
See abscesses that follow lymphatics
Treat with bactrim |
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Term
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Definition
Treponema - 3 species, cause 3 different diseases Borrelia - several species causing endemic, epidemic relapsing fevers and lyme disease
Leptospira interogans: leptospirosis
Spiral shaped, actively motile (periplasmic flagellum) |
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Term
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Definition
All are spiral shaped, obligate anaerobes, can't be gram stained or cultivated in vitro; visualize with silver stain
Acquired through abraded skin/wounds, produce primary skin lesion, produce similar antibody responses
All respond to PCN |
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Term
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Definition
Yaws/Frambesia
Endemic to tropics, spread by direct contact
3-4 wk incubation period
Primary lesion: Mother Yaw -> will produce secondary Yaws in 6-15 wks
Tertiary yaws - gummatous nodules or deep chronic ulcerations |
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Term
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Definition
Pinta
Endemic to Central/South America
Transmitted via direct contact
Get a nonulcerating primary lesion -> develops into hyperpigmented lesions on hands, feet, scalp (may become depigmented after several years)
Tertiary manifestations rare |
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Term
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Definition
Syphilis
Transmitted by direct, usually sexual, contact
Organisms spread through lymphatics and systemic circulation -> hard chancre/primary lesion develops at site of inoculation = highly infectious, lots of spirochete shedding (when baby is most at risk for congenital syphilis)
Pattern of dormancy and symptomatic periods - first get chancre and general illness signs, then latency, then rash and flu-like symptoms, then latency, then tertiary presentation for 1/3 of infected (gummatous skin lesions, aortic aneurysm, CNS symptoms, MR)
Serodiagnosis based on screening for nonspecific antibodies - if they're present, go to confirmatory screening
Also have EIA screening |
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Term
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Definition
Spread of disease caused by treponema pallidum from infected mother to fetus
First trimester: treponema cannot cross placenta - fetus is safe and mother can get treated
2nd and 3rd trimester - if mother has primary or secondary disease, baby will be stillborn; if tertiary disease, baby will have congenital defects |
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Term
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Definition
Visualized with aniline dye (Wright, Giemsa)
Microaerophilic, can be cultivated in vitro
Helical shaped (spirochetes)
Arthropod borne infections
Difficult to grow (need special media) |
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Term
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Definition
EPIDEMIC relapsing fever
Spread to human by spirochete on body louse
Borrelia live in hemolymph of louse -> transmitted when human squish louse (itchy!) and release the infected hemolymph into their abraded skin; penetrate into skin using cork-screw motility
Associated with poor hygiene
Cause relapsing fever due to antigenic variation during course of infection - associated with changes in outer membrane protein (variable major protein)
Diagnose with peripheral blood smear, treat with PCN or tetracycline; avoid arthropod vectors! |
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Term
Borrelia hermsii/parkeri/etc
(Endemic Relapsing Fever) |
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Definition
Borrelia enter hemocele of ticks and then disseminate into all tissues -> spread to human when infected ticks bite (spirochetes in salivary glands)
Ticks normally also infect rodents and rabbits
Cause relapsing fever due to antigenic variation during course of infection - associated with changes in outer membrane protein (variable major protein)
Diagnose with peripheral blood smear, treat with PCN or tetracycline; avoid arthropod vectors! |
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Term
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Definition
Associated with Borrelia burgdorferi, transmitted by female Ixodes hard shell ticks
See a primary skin lesion (erythema migrans) or "bullseye" rash in some -> spirochetemia at site of first infection, then becomes a relapsing/remitting couse -> late stages are worse: arthritis, CNS involvement, cardiac, skin effects
Prevalent in NE, Michigan, Wisconsin and parts of California; endemic on Long Island, CT
Increased cases in summertime - prevent by wearing protective clothes outdoors (esp. hiking and hunting) and checking self for ticks (remove immediately - need 36 hours to get disease); used to be a vaccine but it wasn't effective
Deer Tick -> Mice, Deer (Humans not part of natural cycle)
Difficult to diagnose - no good test so use clinical suspicion
Rx: PCN, tetracycline in early stages; ceftriaxone in late stages |
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Term
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Definition
Spirochete veterinary pathogens that cause kidney infections in animals (humans are not reservoir or primary host)
Infected animals excrete leptospira in urine -> humans with occupational exposure at risk (vets, sewer workers)
Causes conjunctival hemorrhage, kidney infections in humans
Diagnosis: urine sample (also blood and CSF), use PCR
Rx: PCN, tetracycline |
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Term
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Definition
Colonize the human body: skin 10:1, mouth and UG tract 100:1, colon 1,000-10,000:1
Cannot grow in presence of oxygen because they lack superoxide dismutase (killed by free radicals)
Injuries that predispose to intoxification/toxemia: things that reduce perfusion, trauma (GSW, surgery, bowel perforation), metabolic/pathologic processes (diabetes, tumors)
Usually have foul smelling infections
Overwhelmingly, infections are from endogenous sources
Rx: always debride wound and give appropriate antibiotics |
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Term
Gram -
Non-spore forming
Anaerobes |
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Definition
Fusobacterium (spindle shaped)
Bacteriodes fragilis
Prevotella melaninogenica (form black colonies)
Virulence factors: adhesins (capsule, fimbriae), superoxide dismutase, catalase, IgA/M/G proteases, tissue destructive enzymes (hemolysin, phospholipase C, heparinases, lipases, collagenases, proteases)
Above diaphragm: use PCN (fusobacterium, prevotella, etc)
Below diaphragm: bacteriodes fragilis - PCN resistant so use something else |
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Term
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Definition
Anaerobic gram + rod
Causes acne (normal skin flora) |
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Term
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Definition
Anaerobic, gram + rod
(Similar morphology to Nocardia - branched)
Normal flora of mucous membranes, causes subcutaneous infection, prosthetic-device-related infection, IUD infections, cervical facial infection (Lumpy Jaw), thoracic/abdominal/pelvic infections
See sulfur granules (yellow) upon microscopic exam
Rx: surgical debridement, PCN (or clindamycin or erythromycin) |
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Term
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Definition
Anaerobic, gram + curved rod
Normal flora of vagina - second leading cause of vaginosis (watery discharge, fishy smell)
Rx: ampicillin, clindamycin or erythromycin |
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Term
| Clostridia vs. Other Anaerobes |
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Definition
Clostridia - have exotoxins, most infections are monobacterial
Other Anaerobes - no exotoxins, polymicrobic infections (some aerobes too)
Both: cause toxemias or intoxifications |
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Term
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Definition
Causes gas gangrene and myonecrosis
Exogenous (soil) and endogenous (bowel) reservoirs
Toxins: alpha (phospholipase C causes intravascular hemolysis), beta (necrotizing), neuramidase (capillary thrombosis), enterotoxin (alters ileal membrane permeability, food poisoning)
Presentation: predisposing trauma, local edema, crepitus, bullae, pain, cherry red urine (hemoglobinuria from phospholipase C)
Dx: gram stain shows gram + rods (no spores)
Rx: surgical drainage and debridement, PCN |
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Term
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Definition
Gram + anaerobe, causes antibiotic-associated (clindamycin, cephalosporins, oxacillin, PCN) diarrhea and pseudomembranous colitis
Normal flora of bowel, also in hospital environment (nosicomial); causes a superinfection
Cannot grow in lab; use EIA or PCR
At risk: abd surgery, intestinal obstruction, antibiotics/antineoplastic agents
Toxins: A (enterotoxin, causes fluid loss), B (cytotoxin, destroys colon mucous cells); hypervirulent strain cannot turn off toxin production (20-30x more toxins)
Rx: metronidazole, vancomycin (may see pt relapse), stool donor replacement therapy |
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Term
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Definition
Botulism - acute, often fatal; from ingestion of preformed toxin in improperly processed canned food
Toxins -> absorbed in GI tract and block release of Ach in nerve terminals -> target diaphragm = respiratory paralysis (very lethal toxin at low dose)
Medical emergency, treat with specific antitoxin (need lab to serotype)
Prevention: boil foods for 10min, proper food processing
Also have infant (may cause SIDS), wound (same as foodborne), inhalation (bioterrorism) botulism |
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Term
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Definition
Tetanus/Lockjaw - acute disease produced by neurotoxin at site of localized infection
Organism common in GI tract, soil
Local infection -> exotoxin absorbed -> ascends along nerves -> suppresses inhibitory neurons -> excitability and rigidity without direct stimulation of synapses
S+S: headache, irritability, muscle stiffness, masseter spasm, dysphagia, rigidity (backward arching - opsithothonus)
Dx: clinical, site of infection usually not evident (do try to locate and debride wound)
Rx: human tetanus immune globulin, PCN
Prevention: tetanus booster every 10 years |
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Term
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Definition
3 outcomes: asymptomatic infection, Pontiac Disease, Legionnaire's
Opportunistic human pathogen - usually live in water, can grow in stagnant warm water in cooling towers, hot tubs, etc -> exposure with inhalation/aspiration of organisms -> Taken up by macrophages/monocytes -> alters endosome so it can't merge with lysosome -> replicates and escapes
NOT CONTAGIOUS (outbreaks from contaminated areas, not people - think of travel)
Rx: antibiotics (infection can be lifethreatening) - fluroquinolones, doxycycline, azithromycin + rifampin
Dx: urine antigen test + culture of respiratory secretions
Healthcare outbreaks common - susceptible people + old plumbing |
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Term
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Definition
Unusual replication: elementary bodies (small, rigid outer membranes, rugged) bind to receptors and are endocytosed where they prevent binding with lysosome and are unpacked into reticulate bodies (noninfectious, intracellular form, replicating, fragile, make own DNA/RNA but need host ATP)
Obligate intracellular parasites
Inflammatory response may produce some symptoms, but does not clear infection
For all patients that can't be treated with doxycycline, be sure to follow up and test to be sure treatment is working! |
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Term
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Definition
18 serovars - serovar determines what symptoms/manifestation you have:
Serovars A-C: Blinding Trachoma (infectious eye disease where eyelids turn inward and eyelashes scratch cornea)
Serovars L1-L3: Lymphogranuloma venereum (small ulcer proceeds to painful, swollen lymph nodes - get buboes)
Serovars D-K: Genital Chlamydia
Genital Chlamydia - often asymptomatic (leads to PID in women), at risk with nonbarrier contraception/multiple sexual partners/socioeconomic disadvantage
Risk for Reiter syndrome (arthritis, urethritis, eye problems)
With women: easily inducible endocervical bleeding and discharge
With men: urethral discharge, dysuria
TEST FOR CO-INCIDENT CHLAMYDIA IN ALL STD PATIENTS!
Dx: cytologic (Giemsa, IF), cell culture (tissue culture, a must for all legal cases), RNA hybridization with DNA probe (simple and fast), PCR, ELISA
Rx: doxycycline - not for children or in pregnancy (use erythromycin, amoxicillin)
Always treat sexual partner too - prevent spread. Use condoms to prevent. |
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Term
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Definition
3 organisms:
C. pneumoniae: human to human, by respiratory secretions (adult community acquired pneumonia), usually mild illness (headache, sinus percussion tenderness, rhonchi/rales)
C. psittaci: zoonosis from infected birds (rare), can be very serious/fatal (Horder spots, CP, splenomegaly, encephalitis, endocarditis, meningitis); not cultured (hazardous)
C. trachomatis: spread from infected mother to infant, resulting in conjunctivitis and pneumonia in newborn, mild illness, may be seen rarely in immunocompromised adults
Rx: C. pneumoniae and C. psittaci, use doxycycline or erythromycin; C. trachomatis, use erythromycin |
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