Respiratory Pathogens (Golgan) Flashcards
Rhinovirus
MCC of common cold
Transmitted by hand to eye-nose contact
Other causes of cold: coronaviruses, adenoviruses, influenza C, coxsackievirus
Coxsackievirus
Acute chest syndrome: fever and pleuritis
Parainfluenza
MCC of croup (laryngotracheobronchitis) in infants
Can cause bronchiolitis in infants
Rx: cold water humidifiers and aersolized racemic epinepherine
CMV
Common pneumonia in immunocompromised hosts.
Enlarged alveolar macrophages/pneumocytes, contain eosinophilic intranuclear inclusions surrounded by a halo
Rx: Cidofovir, foscarnet, ganciclovir
Common test scenario for:
Prophylaxis - Treat before exposure or sx
Pre-emptive - Treat if exposed (i.e. CMV virus identified) but now symptoms
Empiric - Treat the sx/disease before organism identified
Definitive - Treat the identified organism directly based on sensitivity.
Influenza virus
Type A virus are most often involved
Hemagglutinins bind virus to cell receptors in the nasal passages.
Neuraminidase dissolves mucus and facilitates the release of viral particles.
Inflenza A: worldwide epidemics; pneumonia may be complicated by a superimposed bacterial pneumonia (usually Staph. Aureus)
Influenza B: causes major outbreaks
Antigen Drift: Minor mutation; doesn’t require a new vaccine
Antigen Shift: Major mutation in hemagglutinin or neuraminidase; new vaccine required
Clinical Presentation: Fever, headache, cough, myalgias, chest pain
Vaccination: (all people!) Manadatory for >65 and w/ chronic illnesses
Rx: Oseltamivir (neuraminidase inhibitor)
Associations: Reye syndrome w/ salicylate injestion; Gullain-Barre
Rubeola
Fever, cough, conjunctivitis, and excessive nasal mucus production.
Koplik spots in the mouth precede the onset of the rash.
Warthin Finkedly multinucleated giant cells are a characteristic sign
Respiratory Synctial Virus (RSV)
MCC of pneumonia and bronciolitis (wheezing) in infants
Causes otitis media in older children
Hand washing and use of gloves prevents nosocomial outbreaks in nurseries.
Winter primarily
Rapid detection by nasopharyngeal wash.
Passive immunizations for high risk children.
SARS
First trasmitted to humans through contact w/ masked palm civets (China) and then human-to human contact through respiratory secretions (hospitals, families)
Develop severe respiratory infection
Rx: w/ viral detection by PCR assay or detection of antibodies
Children: no therapy or Vitamin A
Hantavirus pulmonary syndrome
Trasnmission: inhalation of urine/feces from deer mice (Peromyscus leukopus!) in SW US.
Pulmonary syndrome: ARDS, hemorrhage, renal failure
Dx: detect viral RNA in lung tissue
No Rx –> high mortality rate
Chlymydia pneumoniae
Second MCC of atypical pneumonia (esp. young adults)
Seroepidemiologic association w/ CAD
Rx: Doxy
Chlamydia trachomatis
Newborn pneumonia (passage through birth canal)
Afebrile, STACCATO cough, conjunctivitis, wheezing
Rx: erythromycin
Mycoplama pneumoinae
MCC of atypical pneumonia
Common in adolescents and military recruits (closed spaces)
Risk factor for Guillain-Barre
Insidious onset w/ low grade fever
Cold agglutinins in blood –> IgM
Complications: bullous myringitis, cold AHA
Rx: Macrolides
Coxiella burnetti
Usually transmitted without a vector
Contracted by dairy farmers, vets
Associated w/ birthing process of infected sheep, cattle, and goats, and handling of milk or excrement
Atypical pneumonia, myocarditis, granulomatous hepatitis
Rx: Doxy
Streptococcus pneumoniae
Gram positive lancet shaped diplococcus
MCC of typical community acquired pneumonia
Rapid onset, productive cough, signs of consolidations
Urine antigen test is an excellent screen
Rx: penicillin G; vancomycin +/- rifampin (if penicillin resistant)
Staph aureus
Gram positive cocci in clumps
Yellow sputum
Commonly superimposed on influenza or measles
Major lung pathogen in CF and IV drug users
Hemorrhagic pulmonary edema, abscess formation, and pneumatoceles (thin walled air-filled cysts that develop in the lung parenchyma, usually after a pneumonia)
Rx: Naf/Dic ; Vanco for MRSA
Corynebacterium diptheriae
Gram positive rod
Toxin inhibits protein synthsis by ADP-ribosylation of elongation factror 2 involved in protein synthesis
Toxin-induced psuedomembranous inflammation produces a shaggy gray membrane in the oropharynx and trachea
Toxin myocarditis (C.O.D.) and neuropathies
Rx: Erythromycin and antitoxin. DTAP vaccine.
Bacillus anthracis
Gram-positive rod
Habitat: soil
Virulence Factors: Capsule, edema factor, lethal factor, protective antigen
Transimission - direct contact w/ animal skins or products and entry through cuts/abrasions; inhalation (warfare)
Cutaneous anthrax (90-95% of cases) occurs through direct contact; resembles insect bite, but swells to black scab or eschar w/ central area of necrosis. If untreated death in 20%
Pulmonary anthrax: “first sign of disease is death”
Rx: vaccine available for high risk (vets and soldiers in high risk areas)
Cipro
Actinomyces israelii
Gram-positive filamentous bacteria; strict anaerobe; normal flora of tonsils and adenoids
Produces draining sinuses in the jaw, chest cavity, and abdomen; pus contains sulfur granules (yellow specks)
Rx: ampicillin or penicillin G
Nordardia asteroides
Gram positive filamentous bacteria; strict aerobe; partially acid fast
Produces granulomatous microabscesses of the lungs
Frequently disseminates into CNS and kidneys
Rx: TMP-SMX
Often in pts on steroids
Bordatella Pertussis
Gram negative rod
Pili attach to cilia in urt; toxin stimulates AC which catalyzes the addition of ADP-ribose to the inhibitory subunit of G protein complex; toxin also produces absolute lymphocytosis
Produces whooping cough
Transmitted by respiratory droplet
Catarrhal phase - 1-2 weeks –> common cold like sx
Paroxysmal phase - 2-5 weeks; characteristic 4-5 cough in succession on expiration followed by inspiratory whoop
Absolute lymphocytosis
Convalescent phase: 1-2 weeks
Complications: hemmorrhage into skin, conjunctiva, bronchus, or brain from coughing. Otitis media; meningoencephalitis; rectal prolapse; pneumonia
Dx: nasopharyngeal swabs
Rx: erythromycin; DTAP
Haemophilus influenza
Gram negative rod
Common cause of sinusitis, otitis media, conjunctivitis
MCC of epiglottitis (swelling of epiglottis; inspiratory stridor; drooling; rapid onset; thumbrint sign)
MCC of acute exacerbation of COPD
Rx: Cefotaxime or Ceftriaxone
Moraxella Catarrhalis
Gram negative diplococcus
Common cause of typical pneumonia, especially in the elderly
Second MCC of acute exacerbation of COPD
Common cause of chronic bronchitis, sinusitis, otitis media
Rx: Amoxicillin-clavulanate
Pseudomonas aeruginosa
Green sputum (pyocyanin)
Water-loving bacteria most often transmitted by respirators
MCC of nosocomial pneumonia and death due to pneumonia in CF patients
Pneumonia often associated w/ infarction due to vessel invasion
Rx: Piper/Ticlocicillin + aminoglycoside + antipseudomnal quinolone or macrolide
Klebsiella pneumonia
Gram negative fat rod surrounded by a mucoid capsule
Common gram-negative organism causing a lobar pneumonia and typical pneumonia in elderly and nursing homes.
Common cause of pneumonia in alcoholics (MCC is S. pneumoniae)
Typical pneumonia blood-tinged, thick, mucoid sputum
Lobar consolidation and abscess formation are common
Rx: varies w/ susceptibility
Legionella
Gram negative rod (IF or silver stain)
Antigens can be detected on urine screen.
Water loving bacteria (water coolers; mists in grocery stores etc.)
Risk factors: Alcoholics, smokers, immunosuppression (American legion conference was first outbreak!)
Atypical pneumonia w/ high fever, dry cough, flu-like sx
May produce tubulointerstitial disease w/ destruction of the JG appartatus leading to hyporenemic hypoladosteronism (hyponatremia, hyperkalemia, metabolic acidosis)
Rx: Fluoroquinolones, azithromycin
Yersinia Pestis
Gram negative rod
Cause of plague
Transmission: Rat flea ; squirrels in SW USA; person-to-person
Three types of disease: bubonic (most common), pneumonic (transmitted by aerosol), septicemic
Rx of pneumonic: Gentamycin
Cryptococus neoformans
Budding yeast w/ narrow based buds; surrounded by thick capsule. Found in PIGEON excreta
Primary lung disease (40%); granulomatous inflammaiton w/ caseation.
Do not have to be immunocompromised
Rx: Fluconazole
Aspergillus fumigatis
Fruiting body and narrow angled, branching septae hyphae
Aspergilloma - fungus ball (visible on x ray) that develops in preexisting cavity in the lung (i.e. old TB site); cause of massive hemoptysis (invades blood vessels)
Allergic bronchopulmonary aspergillosis: type I and III HS rxn; IgE levels increased; eosinophilia. Intense inflammation of airways and mucus plugs in terminal bronchioles. Repeated attacks may lead to bronchiectasis or interstitial lung disesae. Rx w/ corticosteroids
Vessel invader w/ hemorrhagic infarctions and a necrotizing bronchopneumonia
Rx: voriconazole
Mucor species
Wide angled hyphae w/o septa
Clinical settings: DM, immunosuppressed
Vessel invader produces hemorrhagic infarcts in the lungs
Invades frontal lobes in patients w/ DKA
Rx: liposomal amphotericin B
Coccidiodies immitis
Valley fever
Sperules w/ endospores in tissues
Contracted by inhaling arthrospores in dust while living or passing through arid desert areas in SW; increased after earthquakes
Flu-like sx w/ erythema nodosum (painful nodules in lower leg; inflammation of SQ fat)
Granulomatous inflammation w/ caseating necrosis
RX: usually self-limited; if severe itraconazole or fluconazole
Histoplasma capsulatum
MC systemic fungal infection
Endemic in Ohio and Mississippi river valleys
Inhalation of microconidia in dust contaminated w/ excreta from bats (cave explorers), starlings or chickens (common in chicken farmers)
Granulomatous inflammation w/ caseous necrosis
Yeast forms are present in macrophages
Simulates TB lung disease; produces coin lesions, consolidations, miliary spread and cavitation
Marked dystrophic calcification of granulomas; mcc of multiple calcifications in the spleen
Rx: usually self limited; if sever, itraconazole or liposomal amphotericin B
Blastomyces dermatidis
Yeasts have Broad Based Buds and nuclei
Occurs in Great lakes region, central and southeastern US
Most often associated w/ fishing, hunting, gardening, beaver dams, brush removal
Male dominant disease
Produces skin and lung disease, skin lesions simulate squamous cell carcinoma
Granulomatous inflammation w/ caseous necrosis
Rx: Amphotericin B
Pneumocystis jiroveci
Cysts and trophozoites; cysts attach to type I pneumocytes
Opportunistic infx when CD4
