Microbiology Review/ Pneumonia and TB Flashcards
(96 cards)
Bordatella Pertussis
“whooping cough”, highly contagious, spread by large droplets
gram neg, aerobic coccobacillus, capsulated
humans only reservoir
Clinical manifestation:
Catarrhal phase: rhinorrhea, lacrimation, conjunctival injection, low grade fever
Paroxysmal phase: uncontrollable expirations, followed by gasping inhalation, whooping cough
- convalescent phase: reduced frequency of cough
Complications: pneumonia
tx: azithromycin
Klebsiella Pneumonia
gram neg, nonmotile rod
- facultative anaerobe
seen in UTI, soft tissue infections, endocarditis, CNS infections, severe bronchopneumonia
CXR see cavitary lesions and the patients produce “currant jelly sputum”
Moraxella catarrhalis
gram negative, grows well on blood or chocolate agar
- diploccoi
- catalase and oxidase positive
- pneumonia commonly seen in the elderly, otitis media in children
Neisseria meningitidis
aerobic gram negative kidney shaped diplocci
- oxidase positive, grows on Thayer-Martin media and chocolate media
Seen in dorms/military barracks causing outbreak of meningitis (transmitted through close contact)
Also causes pneumonia
Tx: penicillin G, or 3rd generation cephalosporin
tx people in contact with rifampin
without tx 70-90% will die - this has a high mortality rate
morbidity: limb loss, hearing loss, long-term neurologic disability
Pseudomonas aeruginosa
aerobic-gram negative rod
- produces pyocyanin (blue-green pigment): fluorescent green sputum
- “nosocomial pathogen” picked up in hospital/nursing home
- this will grow anywhere: plants, counters, moist surfaces
Infections:
- HAP, VAP
- CA infections related to hot tubs
- most common cause of otitis externa, “swimmer’s ear”
- puncture wounds through tennis shoes
- Endocarditis, UTIs, skin infections
Bacterial Factors: its got them all!
- exotoxins, endotoxins, pili, flagella, proteases, capsule….. etc.
tx: broad spectrum Abs: always tx with two - extended spectrum penicillin and aminoglycoside (Levo and Gent) - trying to avoid resistance
Chlamydophila psittaci
gram negative, intracellular bacteria (phagocytsed by macrophages)
Disease:
Psittacosis: bird fancier’s pneumonia
- atypical pneumonias
- febrile illness
tx: tetracyclines, fluoroquinolones, macrolides
Chlamydophila pneumoniae
80% of adults are seropositive - and is common infection in children under five
- causes an atypical pneumonia with non-productive cough often preceded by nasal congestion, sore throat, hoarseness and h/a
tx: tetracyclines, macrolides, fluoroquinolones
CXR shows diffuse infiltrate, exam reveals crackles and ronchi in the lungs
what do you tx atypical pneumonia with?
levofloxacin, arithromycin, azithromycin
Coxiella burnetti
“Q fever”
- gram negative that is hosted in monocytes
- not completely eliminated after acute infection: will continue to multiply in IC patients and can cause endocarditis
- lives in mammals, birds and ticks
Major outbreaks: related to sheep and goats during lambing season
“Q fever” : 60% will fight off without disease, 38% will have self-limited disease, 2% will have more prolonged disease: pneumonia, hepatitis, rash, meningitis, encephalitis, pericarditis, myocarditis
- females can have chronic uterine infection –> spontaneous abortions
Q fever endocarditis = fever of unknown origin, see intermittent fever, vegetations are frequently absent, have cerebral emboli, renal insufficiency, splenomegaly, hepatomegaly (due to vegetations)
tx: doxycycline for 2 weeks in acute case, then use doxycycline + hydroxycholoquine (an anti-malarial that increases the pH), for 18-36 months for endocarditis
francisella tularensis
“tularemia” infectious zoonosis, small aerobic pleomorphic gram negative bacillus
- harbored in rabbits, squirrels and muskrats
- human acquired through contact with animal tissue, meat or bite of infected tick or deer fly
Clinical:
- ulceroglandular (fever, swollen lymph nodes, ulcer at the site, sore throat) presentation,
- glandular, (fever and constitutional syndromes)
- ocuoglandular,
- typhoidal, (just fever only)
- oropharyneal, (uncommon in US, affects mucus membranes of mouth = pharyngitis and pharyngeal ulcers)
- pneumonic (most serious, caused by inhalation exposure, fever, dry cough, substernal discomfort, peribronchial infiltrates, bronchopneumonia, hilar adenopathy)**
tx: gentamicin, doxycycline, ciprofloxacin
mortality is less than 1% if properly treated
bacillus anthraxis
- gram positive, non motile rob, aerobic, catalase positive, hemolysis negative
- grows on sheep agar
- zoonotic infection common in goats sheep, cattle, pigs, horses: related from meat wool, hides, bones, hair - soil contaminated with spores
clinical: inhalation manifestations
- “mediastinal widening”
- mediastinal adenopathy, pleural effusion, rapidly fatal if not tx with multiple anibiotics and pleural drainage*
- most commonly see cutaneous form
- GI sx, meningeal sx
tx: multi drug abs and pleural drainage, vaccination is available
prognosis: 45% mortality of inhalation in 2001, 20% mortality for untreated cutaneous lesions
Yersinia pestis
another zoonotic, coccobacillus, nonmotile, non spore forming
spread through rodents and fleas - prarie dogs are common host
clinical: patients have bubos (nodules), septicemia and pneumonia
Bubonic plague: swollen tender lymph nodes, closest to site of initial infection, fever, chills, body aches, h/a’s. if untreated develop confusion, delerium, convulsions
Septicemic plague: DIC, HTN, renal failure, ARDS type picture
Pneumonic Plague: highly fatal, die w/in 24 hours - see fever, cough, tachycardia, chills, hemoptysis, circulatory collapse
tx: streptomycin for pneumonic
tetracyclines for bubonic form
chloramphenicol for meningitis
Leptospirosis
- spirochete with terminal hook, use silver staining or dark field microscopy,
carried in rodents, dogs, pigs, cattle, sheep
- colonizes renal tubules and excreted in urine
transmission: penetrates the skin, mucus membranes and through contaminated water
Early phase: fever myalgia, h/a, nausea, vomiting, ab pain, conjunctival swelling
“Weil’s disease” = late manifestation - jaundice, hemorrhage, thrombocytopenia
ddx: via agglut test
tx: doxycycline or penicillin
H. influenza
encapsulated gram negative rod, aerobic or facultative anerobic - grows on chocolate agar: Factor X and Factor V
- used to cause epiglottis commonly in children, though now they are vaccinated (high fever, chills, sore throat - see thumb sign on CXR due to swollen epiglottis - though may be seen in unvaccinated children)
transmitted via resp. droplets, type B used to be most common cause of meningitis in children and otitis media
Clinical:
- Meningitis in children under 5 y/o (though not seen much more)
- epiglottitis is life threatening in children - fever, chills, dysphagia, drooling, respiratory distress with stridor (need to distinguish from croup, steeple sign on XRAY) - course is rapid
- pneumonia: fever, cough, lobar consolidation, smoking is a risk factor
- sinusititis, otitis media
tx: 3rd generation cephalosprin
- have vaccination for type B: Hib
tx people that come into contact with this with rifampin, used for prophylaxis
Corynebacterium diptheriae
- gram positive, “club shaped”, aerobic, grows on throat and pharynx of humans - diptheria forms a toxin that is transmitted via respiratory droplets
“Respiratory Diptheria” - sore throat, malaise, thick tonsilar exudate that is very sticky (don’t scrape it off) - “gray membrane”
“bull neck” huge cervical lymphadenopathy, develop stridor
- if membrane extends down over trachea it can lead to obstruction
tx: erythromycin and an antitoxin
prevention: vaccination - dTap
Legionella Pneumophilia
weakly gram negative, facultative intracelular
- “grows on charcoal yeast extract”
- grows in water, A/C systems and is transmitted through aerosols from these systems - no human/human transfer
risk factors: smoking, age greater than 55, alcohol intake
Pneumonia: fever, malaise, cough, chills, h/a, c/p, diarrhea
distinguished from other pneumonias due to “myalgias, h/as and diarrhea” also see mental confusion
- fever is elevated and lower than expected pulse
“pontiac fever” : fever, sore throat, myalgia, h/a, fatigue, short duration lasting on average 3 days
ddx: antigen urine test
tx: fluoroquinolones, azith, erythromycin + rifampin for IC patients (these are all used for atypical pneumonia)
mycoplasma pneumonia
smallest free living bacteria, no cell wall, cause of atypical pneumonia
- needs cholesterol for culture,
tranmitted through resp. droplets
- seen in atypical pneumonia in dormitory and military barracks:
**usually seen in young people: ages 5-20
pneumonia: fever, malaise, h/a, cough, “walking pneumonia” with nonproductive cough - sx will last 3-4 weeks
also causes bullous myringitis: blood filled tympanic membrane
ddx: positive cold agglutinins! usually made on clinical basis though
tx: macrolides (erythromycin, azithromycin, clarithromycin) or tetracyclines
will have IgM autoantibody that is directed against the antigen of RBC’s
streptococcus pneumonia
- most common CAP *
gram positive, dipplococci, lancet shaped, grows on blood agar plates, alpha hemolytic, optochin sensitivie - grows in upper respiratory tracts
- has a polysaccharide capsule
risk factors: influenza infection, COPD, CHF, alcoholism, asplenia - initially colonizes the nasopharynx is then aspirated –> pneumonia
“typical pneumonia”: most common cause, shaking chills, rigos, lobar consolidation, and “rusty blood tinged sputum”
Adult menintitis, otitis, sinusitis are other effects
tx: beta lactams, macrolides, fluoroquinolones
tx of meningitis: 3rd generation cephalosporin
Staphylococcus aureus
gram positive cocci in clusters, catalase and coagulase positive, beta hemolytic, grows in small yellow colonies on blood agar, ferments mannitol
common pathogen of nasal flora - 25% present in popluation - transmission through hands, sneezing, surgical wounds, contaminated food (potato salad, custards, canned meats)
- there are over 50 difft. virulence factors
3 toxin mediated diseases: staph food poisoning, staph TSS, staph scalded skin syndrome
Clinical manifestations:
- impetigo, folliculitis, furuncle, abscess, cellulitis, mastitis, nec. fascitis, wound infections
- bacteremia, endocarditis (roths spots, oslers nodes, janeway lesions, peticheai)
- pericarditis, osteomyelitis
pneumonia: nosocomial salmon colored sputum
Staph food poisoning: 2-6 hours after eating, nasuea, vomiting, diarrhea
TSS: due to TSST-1 super antigen: have fever, hypotension, desquamation of palms and soles
tx: gastroenteritis is self limiting - no tx
for non MRSA = tx with nafcillin/oxacillin
MRSA tx: Vancomycin
what do you treat MRSA with?
vancomycin
non drug resstant staph tx?
nafcillin/oxacillin
pneumocystis jirovecii (carinii)
- fungus that an obligate extracellular parasite, seen on silver stain, hat shaped
- opportunistic in HIV patients with CD4)
tx: sulfamethaxazole/trimethoprim (SMX/TMP= bactrim)
histoplasma capsulatum
fungi that is seen in the central US - its a facultative intracellular parasite found in RES (retic. endothelial) cells
- found in soil, caves, abandoned buildings with bird and bat guano”: spleunking, cleaning under bridges
transmission: through disruption of soil,
endemic to miss. river and ohio valley
ddx: silver stain with thin based budding yeast
presents with acute pulmonary syndrome: fevers, chills, fatigue, non prod, cough, anterior chest discomfort and myalgias
chronic pulmonary syndrome: progressive and often fatal, elderly, IC and COPD pts at most risk
xRAY: acute pneumonia with patchy lobar infiltrates
chronic see upper lobe infiltrates, cavities and fibrosis that mimics TB
Tx: Itraconazole, amphotericin B
Blastomyces dermatitidis
silver stain shows “broad based budding yeast” - thermally dimorphic fungus
- assoc. with soil and decaying vegetations
- endemic to north and south central and great lakes
acute pulmonary sx: fever, malasie non. prod. cough, CXR shows lobar, multilobar or nodular infiltrates and skin lesions
chronic pulmonary: fever, nigh sweats, cavitary lesions, fibrosis - CXR shows cavitary nodules
tx: all patients should be treated ! itraconazole in mild cases, severe cases in amphotericin B
