RESPIRATORY FINAL PATHOGENS Flashcards
STREP PNEUMONIAE
Gram + lancet shaped diplococci
Catalase -, alpha-hemolytic, inhibited by optochin
+ Quellung reaction
Lysed by bile
Polysaccharide capsule—> virulence factor—> dangerous in asplenic pt
MOST COMMON CAUSE OF PNA (CAP) especially > 60
Lobar pneumonia*
Rust colored sputum
CXR—> white consolidated lobe
Also most common cause of meningitis in ADULTS
Otitis media in children*
HAEMOPHILUS INFLUENZAE
**Vaccinate for between 2-18 months
Gram -, pleomorphic ROD
Grows on “chocolate agar” (needs V or NAD and Hematin or X)
Polysaccharide capsule (capsule B is the worst)
Aerosol transmission
Obligate human parasite
CAUSES: TYPICAL PNA; Meningitis in 3 mon-2 years without vaccine; bronchitis and epiglottis in unvaccinated toddlers “Catcher’s stance”
CHERRY RED EPIGLOTTIS:
Inflamed epiglottis; inspiratory strider; drooling
USE:
Beta lactam or 3rd generation cephalosporin
Rifampin—> prophylaxis
CAN EXACERBATE COPD
MORAXELLA CATARRHALIS
Gram -, DIPLOCOCCI, part of normal URT flora
Most common cause OF: OTITIS MEDIA and SINUSITIS
Cause of TYPICAL PNA
Causes COPD exacerbation
Penicillin resistant**
Treat with: Macrolides; Augmentin; 2nd/3rd gen cephalosporin; Bactrim
STAPHYLOCOCCUS AUREUS
Gram +, catalase +, coagulate +, beta-hemolytic
Plate on mannitol—> turn agar YELLOW
“Bundle of grapes appearance”
Protein A—> main virulence factor; bind to Fc of IgG
CAUSES:
TYPICAL PNA: patchy infiltrates on X-RAY; icosahedron shaped lamps, post-viral bacterial pneumonia
Most common cause of septic arthritis; abscesses
Rapid onset of acute bacterial endocarditis in IV drug users— TC valve
Most common cause of osteomyelitis
TOXIN MEDIATED DISEASES:
Scalded Skin Syndrome—> exfoliatin toxin
TSS—> super antigen, TSST, from tampon
Staph FP—> in meats, custards, mayo
MRSA RESISTANT—> use vancomycin
If methicillin sensitive—> use naficillin
KLEBSIELLA PNEUMONIAE
Gram -, ROD, encapsulated, oxidase (-), forms lactose fermenting colonies on MacConkey agar, urease +
Currant-jelly sputum
CAUSES:
PNA in alcoholics, abscesses, aspiration
UTI’s in association with catheters
CXR—> may look like TB
Treat with:
Carbapenem, 3rd generation cephalosporin, ciprofloxacin
PSEUDOMONAS AERUGINOSA
Thrives in aquatic environments
Gram -, ROD, oxidase +, catalase +, aerobic, non-fermenting
Pyocyanin—> blue green pigment; Fluorescein expression
“Grape-like odor”
Exotoxin = ADP = inhibiting protein synthesis and the liver is the primary target
CAN CAUSE:
Hot tub folliculitis
Eye ulcers
Cellulitis in BURN patients (blue-green puss)
TYPICAL PNA—> in patients with CGD or CF**
Otitis externa
UTI
Diabetic osteomyelitis
Erythema gangrenosum—> black necrotic skin lesions
Treatment:
Anti-pseudomonas beta-lactam: piperacillin + tazobactam
Aminoglycosides + beta-lactam and fluoquinolones
COXIELLA BURNETII
in FARMERS
Gram +, intracellular obligate, spore former, resistant to heat/drying, extracellular existence, spore inhalation causes Q fever from ANIMAL FECES
TYPICAL PNA—> mild pneumonia, soaking sweats 2-3 weeks after infection
No antibiotics needed**
May cause hepatitis
MYCOPLASMA PNEUMONIAE
ATYPICAL PNA = “walking pneumonia”
Smallest, free living extracellular bacteria, NO CELL WALL, pleomorphic, motile, round, facultative anaerobe Sterols in membrane and requires cholesterol for culture “Fried egg colonies” “Mulberry-shaped colonies” \+ Cold agglutinins Lyse RBC’s Plated on EATON AGAR Affects young adults and military
Attaches to respiratory epithelium via P1 protein and inhibits ciliary action
Produces: H2O2, Superoxide radicals, and cytolytic enzymes
Functions as a SUPER ANTIGEN
CXR: worse than clinical symptoms = streaky infiltrates
Treatment: macrolide, tetracyclines, fluoroquinolones
CHLAMYDIA PNEUMONIAE
Atypical PNA
Obligate intracellular bacteria; w/ elementary bodies (infectious form)/reticulate bodies (active form)
Not seen on gram stain and cannot make it’s own ATP
Cell wall lacks muramic acid
Aerosol transmission
CAUSES WALKING PNEUMONIA:
“Hoarse voice”
In adults and elderly
Treat: Doxycycline or Erythromycin
CHLAMYDIA PSITTACI
Atypical PNA w/ hepatitis
Obligate intracellular bacteria; w/ EB and RB’s
Not seen on gram stain; cannot make own ATP; lacks muramic acid
IN BIRDS (especially parrots) spread through dust of dried bird feces
Cough—> mucopurulent
Develops 1-3 weeks after exposure
LEGIONELLA PNEUMOPHILA
Atypical PNA
Weakly gram -; parasite for free living amoebas; oxidase +, urine antigen +
Requires cysteine and iron for growth in media
Water organism: air cooling system, whirlpools
Silver stain
“Charcoal” agar
Facultative intracellular
Common problem in smokers over 55 with high alcohol intake and in immunosuppressed (Renal transplant patients)
CXR: one lobe patchy
LEGIONARRES DISEASE: more common in smokers; atypical PNA; HYPONA+; high fever and diarrhea
Treat: Macrolides and fluoroquinolones
BURKHOLDERIA CEPACIA
Atypical PNA
Oxidase +, aerobic gram -, BACILLUS
Grows in water, soil, plants and animals
PEOPLE WITH CF @ greatest risk**
Highly drug resistant
ASPERGILLUS FUMIGATUS
Pulmonary Fungi
Opportunistic fungi; monomorphic; septate hyphae branching at 45 degrees; catalase +
Can cause formation of:
Aspergilloma—> fungal ball in TB lung cavitation
Allergic Bronchopulmonary Aspergillosis—> wheezing, fever, migratory pulmonary infiltrates, type 1 hypersensitivity, increased IgE
Invasive Aspergillosis—> affects immunocompromised (neutropenia)
Toxin—> aflatoxin—> hepatocellular carcinoma
TREAT: Less serious—> Voriconazole; Angioinvasive—> Amphotericin B + surgical debridement
HISTOPLASMA CAPSULATUM
Pulmonary fungal infection
Endemic to Mississippi River valley, Ohio river valley, Midwest/Central US; been in a CAVE or CHICKEN COOP (bat or bird feces)
KOH stain; dimorphic
Hyphae with microconidia and tuberculate macroconcidia
“Spelunker’s disease”
Hepatosplenomegaly may be present
Small intracellular yeasts which fill infected RES cells to the brim;
Lesions tend to calcify as they heal
Causes: FUNGUS FLU (A PNA)
Treat: Local/mild—> conazoles; Systemic: Amphotericin
COCCIDIOIDES IMMITIS
Pulmonary fungal infection
Can cause: acute pulmonary disease, chronic pulmonary disease, or disseminated infection; dimorphic fungi
Endemic in the SW USA
Transmission: inhalation of spores
Causes DESERT VALLEY FEVER: with desert bumps = erythema nodosum on the shins
Pulmonary lesions tend to calcify as they heal
TREAT: Local: conazoles; Systemic: amphotericin B
BLASTOMYCES DERMATITIDIS
Pulmonary fungal infection
“Rotting wood” dimorphic fungus shaped like a butterfly
Endemic to: upper Great Lakes, ohio, Mississippi River beds, and SE seaboard of the US and Northern Minnesota into Canada region
Broad based budding yeasts and a double cell wall
CXR: “hazy”
KOH stain+
TREAT: local: Itraconazole; Systemic—> Amphotericin B
ORTHOMYXO VIRUS
“THE FLU”
Influenza A-C (A is the worst)
SsRNA; segmented; lipid envelope; helical; replicates in nucleus
Virulence = HA—> binds to RBC’s; NA—> breaks down neuroA acid
REYES SYNDROME: complication in children who use aspirin; liver/brain disease
Treat: Vaccine; CI in those with egg allergies
Amantidine; Rimantidine; Z/O
Pneumonia can be a complication of the flu and GUILLAIN BARRE SYNDROME
CORONAVIRUS
Can cause SARS
Enveloped helical + SsRNA
Causes SARS: fever of > than 100; flu-like illness; dry cough; SOB; progressive hypoxia
Can also cause “common cold”
Treat: Broad spectrum antibiotics; ribavirin; corticosteroids
HANTA VIRUS
BUNYAVIRIDAE
- SsRNA enveloped virus
Transmitted via RODENT excrement (reservoir: deer mouse) in the FOUR CORNERS region
Causes a pulmonary syndrome characterized by: cough, myalgia; SOB; tachycardia; pulmonary edema; effusion; hypotension
50% mortality “hemorrhagic fever”
MUST REPORT TO CDC
MYCOBACTERIUM TUBERCULOSIS
Acid fast RODS (bacillus); obligate aerobes
Weakly gram +, non-motile; aerobic
Virulence from—> cord factor, sulfatides, siderophore
Green with AURAMINE-RHODAMINE staining
Causes: delayed hypersensitivity and cell mediated immunity; formation of Ghon complex: calcified tubercle in the middle or lower lung zone + perihilar LN granuloma; cavitary lesions
Treat: First line agents: rifampin, ethambutol, pyrazinamide, isoniazid
M AVIUM INTRACELLULARE
MAC
Acid fast rods; obligate aerobes; contain mycolic acids resistant to desiccation; causes pulmonary GI and disseminated disease
Presents in: AIDS patients; cancer patients; those with chronic lung disease
Most common cause of NTM lung disease** and FUO in AID’s patients
Disseminated disease in AIDS patients with CD4 < 50 treatment: Clarithromycin; rifampin; ethambutol;
Pulmonary: clarithromycin; rifampin; ethambutol
Lymphadenitis: excision surgery
M KANASASII
Upper cavitary lung disease
Acid fast rods; obligate aerobes; mycolic acids so highly resistant
Presents in: AIDS, cancer, and those with chronic lung disease (CD4 < 50)
Photochromogen**
Use: Isoniazid, rifampin, ethambutol FOR 18 MONTHS
Picked up from environment; long time smokers; Midwest; SW USA
CANDIDA ALBICANS
Yeast; endogenous to our mucous membrane flora; Pseudohyphae and true hyphae invade tissues
Causes: oral thrush; esophagitis in HIV patients Can be scraped off
(Creamy white exudate with red base)
Do: by KOH wet prep stain
Treat: Amphotericin, fluconazole; Caspo or micafungin
TOXOPLASMA GONDII
Opportunistic infection in HIV
Due to CAT FECES in pregnant women; can cross the placenta
CD4 < 100
CXR: ring enhancing lesions
Presents with: fever, HA, neuro deficits, LN enlargement
Prophylaxis: BACTRIM
PNEUMOCYSTIS JIROVECII
MOST COMMON INFECTION IN HIV PATIENTS
“Flying saucer appearing fungus” Meth-Silver stain; Wright-Giemsa stain
Can cause: interstitial pneumonia in AIDS patients (CD4<200)
Invades lungs @ an early state then remains latent
CXR: ground glass opacities
Presents: fever, SOB, non-productive cough, eventually death
Prophylaxis: Bactrim + steroids
CYTOMEGALOVIRUS
“MONO”
Large DSDNA enveloped, icosahedral virus
Persistent infection in fibroblasts, epithelial cells and macrophages
Characterized: thrombocytopenia purpura “blueberry muffin baby” along with jaundice and hepatosplenomegaly
Can cause: chorioretinitis/blindness in HIV patients in CD4 <100
“Owl’s eye inclusions; fluffy infiltrates”
HHV-8
HERPESVIRUS
Large DSDNA enveloped icosahedral virus
Reservoir in humans; can turn on VEGF, playing a role in developing KAPOSI’S SARCOMA
CRYPTOCOCCUS NEOFORMANS
Encapsulated yeast; monomorphic
PIGEON DROPPINGS
Causes: leading cause of meningitis in AID’s patients (CD4 < 100)
Sx: altered mental status, fever, HA
Dx: lumbar puncture; India ink stain: yeast w/ surrounding halo
Treat: amphotericin + fluconazole
