Respiratory Flashcards
Enterovirus D68 Features
Transmission: respiratory and GI secretions
Underlying condition: asthma
ROS: mild to severe resp illness including pneumonia
Complication: linked to flaccid paralysis
Moraxella catarrhalis Features
G-ve diplococcus, strict aerobe
Oxidase: positive
Motility: non-motile
Penicilin resistant: produce B-lactamases
*mostly colonize URT in children but also in pt’s w/ COPD
Haemophilus influenzae Features
Pleomorphic, needs factors X (hemin) and V (NAD) for growth
- encapsulated
- IgA protease
Chlamydophila pneumoniae Features
Transmission: droplets
Clinical syndrome: atypical pneumonia and bronchitis
Legionnaires Dz
Water source, atypical pneumonia, CNS sx’s (confusion/HA), GI sx’s (N/V/D), hematuria
Pneumocystis jirovecii Features
CM component: cholesterol instead of ergosterol
CW: contains chitin and glutan
Risk: CD4 count < 200
Klebsiella pneumoniae Features
G-ve bacillus, non-motile Oxidase negative - Catalase positive + Ferments lactose Encapsulated Facultative anaerobes
Klebsiella pneumoniae Bronchopneumonia
ROS: thick, bright red gelatinous sputum (“currant jelly” sputum), typical pneumonia w/ many abscesses
Risk: pt’s w/ chronic lung dz or alcoholism
Histoplasmosis
ROS: fever, cough, CP
Course: severity depends on infectious dose and pt’s health status, high intensity exposure will cause sx’s in most pt’s
Diagnosis: silver stain, thick blood smear w/ Giemsa stain
Intubated pt is at risk for what?
Typical HAP caused by Pseudomonas or Klebsiella
Post-streptococcal Glomerulonephritis
Type III Hypersensitivity, immune complexes of Abs against S. pyogenes serotypes M12 and M14 circulate w/ the ag and block small diameter blood vessels
Pneumocystis Pneumonia (PCP)
Organism: Pneumocystis jirovecii
ROS: atypical pneumonia w/ interstitial mononuclear infiltrates (predominantly plasma cells)
*most common serious opportunistic infection in HIV pt’s
Corynebacterium Features
G+ve rods, non-spore forming, aerobic
Legionella pneumophila Features
Facultative intracellular (in alveolar macrophages) causes atypical pneumonia
Transmission: aerosols from water sources
Diagnosis: urine ag test (for serogroup 1), silver stain, BYCE agar
Chlamydophila psittaci Features
Clinical syndrome: atypical pneumonia (Ornithosis)
Exposure: parrot/bird (feces)
-Obligate intracellular-
Infectious form: elementary bodies (EBs)
Noninfectious form: reticulate bodies (RBs)
M-protein
Destroys C3 convertase, thus no C3b is produced and pt cannot opsonize
*Strep pyogenes (GAS)
Cryptococcus neoformans Pathogenesis
Capsule: anti-phagocytic, provides the most virulence, down regulates immune response
- oxidizes catecholamines to prevent phagocytic oxidative damage
Blastomyces dermatitidis Features
Dimorphic (mold in the cold, yeast in the heat)
Tissue form: large yeast w/ broad-based buds and thick CW
Exposure: decaying organic matter (soil)
Geography: NC and SC
Rhinovirus Features (common cold)
4 viral capsid protein: VP1, VP2, VP3, VP4
Acid labile: yes (can’t survive in GIT)
Incubation: 48-72 hours
Transmission: 2h - 7d
Complication: can exacerbate COPD and asthma
Respiratory Diphtheria
ROS: sudden onset of educative pharyngitis, sore throat, fever, malaise
Course: thick pseudomembrane dev over pharynx, can cause resp obstruction
Complications: carditis and neuro sx’s (recurrent laryngeal n. palsy)
Calcifying lesions in the lung?
Fungi tend to cause dystrophic calcification in the lung because the indigestible complex carbohydrates that make up their CW
Aspergillus infections
Allergic aspergillosis: exacerbates asthma and CF
Invasive aspergillosis: risk is immunocompromise, can disseminate
Aspergilloma: formation of fungus ball in preexisting cavitations likely caused by TB or lung abscesses
Strep Pneumoniae
ROS: rusty sputum
Seasonality: winter/early spring
Pneumolysin: damage to epithelium by messing w/ membrane stability, it suppresses PMN chemotaxis and produces H2O2 to inhibit respiratory burst
Influenza Virus Features
Nucleocapsid: 8 segments of -ssRNA (8 for A and B; 7 for type C)
Subtypes: A is further classified by subtype on basis of hemagglutinin and neuraminidase
Hemagglutinin (H/HA): 18 types total
Neuraminidase (N/NA): 11 types total
Replication: in nucleus, virions bud from plasma membrane
Bordatella Pertussis Diagnosis
Bordet-Gengou medium
NO cotton swab, NO throat swab
*acellular FhA and pertussis toxin in the DTaP vaccine
Most common cause of CAP?
Streptococcus pneumoniae
Moraxella catarrhalis Diagnosis
Blood and chocolate agar (round, opaque colonies), hockey puck sign, colonies take pink color after 48 hours
(To differentiate from Neisseria):
DNase: positive
Nitrate reduction: positive
Aspergillis fumigatus Features
Monomorphic (bc opportunistic)
- filamentous fungus w/ septate hyphae branching dicothotomously at acute angles
Exposure: decaying matter, air, soil
Chlamydophila psittaci Virulence
CW: no PG, has LPS with weak endotoxicity, major outer membrane protein (MOMP) is major virulence factor Elementary Bodies (EBs): attach to microvilli and penetrate into cell, the outer membrane of EBs inhibits fusion to the lysosomes Reticulate Bodies (RBs): divide to become smaller EBs again and then lyse the cell
Moraxella catarrhalis Infections
Acute exacerbation of COPD in elderly, pneumonia, bacteremia, periorbital cellulitis, conjunctivitis
Rhinovirus Pathogenesis (common cold)
Receptors: ICAM-1 and LDL-R
Transmissible due to stability in environment (naked), grows at 33-35C so ideal for upper RT infection, af drift so high # of serotypes
Moraxella catarrhalis Pathogenesis (otitis media)
Colonization of nasopharynx then migrates to middle ear through Eustachian tube, migration usually precipitated by viral URI
Pseudomonas aeruginosa Risk
CF pt’s risk of dev pneumonia, burn pt’s (blue green pus), neutropenic pt’s
Haemophilus influenza Culture and Dx
Coagulase: negative
Catalase: positive
Culture: requires chocolate agar w/ factor X (hemin) and factor V (NAD)
Melioidosis Clinical Features
Incubation: about 9d
ROS: pneumonia in adults, localized skin infection in children
Diagnosis: Ashdown’s agar (shows corn flower head morphology)
Moraxella catarrhalis Pathogenesis Characteristics
Adherence to resp epithelium, intracellular invasion, complement resistance, biofilm formation, induction of inflammation, acts as co-pathogen
Mycoplasma pneumoniae Virulence
P1 protein: used for tropism to attach to cilia and microvilli of bronchial epithelium causing stasis of cilia
Community Acquired Respiratory Distress Syndrome (CARDS) Toxin: leads to cytotoxic effect and causes persistent cough
Produces H2O2: causes tissue destruction and damage to RBC membranes
Cryptococcus neoformans Features
Monomorphic (bc its opportunistic), encapsulated, urease +ve
Transmission: bird droppings (soil)
Lysozyme
.
Streptococcus pyogenes (Group A)
- Beta hemolytic
- Bacitracin sensitive
- patechiae on palate
Haemophilus influenza Pathogenesis
Pili, and non-pilus adhesions
LPS: impairs ciliary function, endotoxin
Capsule: antiphagocytic and composed of polyribose ribitol phosphate (PRP)
IgA proteases: >30 different proteases identified
Adenovirus Pathogenesis (common cold)
Receptor: CAR (coxackie adenovirus receptor) cell surface glycoproteins belonging to IgG superfamily
Fiber protein: enables attachment to host cell
Inclusion: basophilic intranuclear inclusion bodies
Corynebacterium diphtheriae Epidemiology
Vaccine: DTaP it is the D for diphtheria toxoid
<10 cases/yr in US
IgA
Protective toward viral infections of upper respiratory tract
Moraxella catarrhalis Pathogenesis (COPD exacerbation)
Altered mucociliary function, airway colonization and infection, triggered by acquisition of new strains
Lactoferrin
Limits availability of iron for growth of bacteria
Coronavirus Pathogenesis (common cold)
Envelope spikes (peplomer): bind to host cell
Hemagglutinin: RBC agglutination
*nucleoprotein, matrix glycoproteins
Corynebacterium diphtheriae Pathogenesis
Virulence factor: diphtheriae exotoxin
Non-invasive: does not enter into bloodstream
Affect: local and systemic sx’s, inflammation and formation of pseudomembrane, damage to organs
SARS Features
ROS: h/o fever + 1 or > sx of LRTI (dyspnea, cough, etc)
Diagnostics: Abs by ELISA, or viral DNA by RT-PCR
Reservoir: bats
Intermediate host: civet cats
Incubation: 2-10d
Peak shedding: 6-11d post start of illness
Hemophilia influenzae Features
Most common cause of epiglottitis, can cause otitis media, pneumonia and meningitis
Pleomorphism, G-ve, coccobacillus, facultative anaerobe, normal component of upper RT flora
Streptococcus Features
G+ve cocci, in pairs or chains, mostly facultative anaerobes, catalase negative Capsule: hyaluronic acid Hemolytic: seen on blood agar Lancefield grouping: 21 serologic groups M protein: 80 serotypes Dx: PCR, RFLP, DNA sequencing
MERS Features
Animal Host: Arabian camels
Evaluation: done 14 days after possible exposure
ROS: fever w/ or w/o chills, cough, dyspnea, hemoptysis, sore throat, GI sx’s, abnml CXR
Comorbidities: DM, HTN, chronic cardiac or kidney dz
Dx: rRT-PCR, serology
Coronavirus Features (common cold)
Capsid: spike protein on envelope (important ag protein)
Incubation: 2-5d
Transmission: via respiratory droplets (3 hours)
*MERS and SARS
Mycoplasma pneumoniae Features
Does not Gram stain, has sterols in CM
Transmission: droplets
#1 cause of atypical pneumonia (CAP) <40yo
Diagnosis: > or = to 4 fold increase or decrease in Ab titer, or IgM cold agglutinins
*intrinsically resistant to B-lactams bc lack CW
SARS Clinical Course
Prodrome: 3-7d, temp >38C, malaise, HA< myalgia, no URT sx’s usually
Respiratory phase: non-productive cough, dyspnea, resp failure
CXR: pneumonia by 7-10d
Labs: lymphopenia
Dx: serology, RT-PCR
Cocciioides immitis Features
Dimorphic
Tissue form: large round double-walled “spherules” (20-150 microns) containing uninucleate endospores
Geography: desert/dry areas so SW of US and NW Mexico
- spherules: protect it from phagocytosis
*most virulent of all human mycotic pathogens
Corynebacterium diphtheriae Features
Gray-to-black colonies of dub shaped G+ve rods arranged in V or L shape
Granules: aka volutin produced on Loeffler coat serum medium stain metachromatically
Pseudomonas aeruginosa Features
Most commonly causes Otitis Externa, strict/obligate aerobe, common cause of atypical pneumonia
Pigment: blue green
MDR
Hantavirus Pulmonary Syndrome (HPS) Features
Transmission: rodent urine/droppings/saliva via airborne transmission most commonly
Seasonality: fall/winter when it gets cold and mice come inside
Flu Sx’s in Adults
Rapid onset after 1-4 day incubation Sudden malaise and HA lasting few hrs Abrupt raise in fever, chills, myalgia, loss of appetite and nonproductive cough (can last 3-8 days) Recovery: complete in 7-10 days Contagious: end of day 1 for next 7 days
Klebsiella pneumoniae Virulence
- Large capsule
- Pili: type 3 strains have pili that mediate attachment for tropism and for biofilm formation
- Endotoxins prevents phagocytosis and blocks C3b
HPS Pathogenesis
Increase in capillary permeability that results from endothelial damage caused by host immune response to viral ag
- widespead exudate caused by the permeability
Influenza Nomenclature
Type/Host of origin/Geographic origin/Strain #/year of isolation/Subtype of HA and NA
E.g. - A/Avian/Hong King/03/68 (H3N3)
Adenovirus Features (common cold)
Capsid: naked icos w/ fiber VAP for tropism
Acid labile: no (it can survive in GIT)
Incubation: 4-8d
Transmission: 7d-3mo
Vaccine: approved only for military recruits
ROS: URI, hemorrhagic cystitis, conjunctivitis
Bordatella pertussis Virulence
Pili: filamentous hemagglutinin (FHA) mediates attachment to ciliated epithelium
Pertussis toxin: ADP-ribosylates Gi keeping high levels of intracellular cAMP will shut down chemokine receptors and pt will develop hypoglycemia due to increased insulin secretion
Legionella pneumophila Virulence
Inhibits fusion of phagosome w/ lysosome, pore-forming toxin kills macrophages
Exudate: alveoli filled w/ fibrin, PMNs, macrophages and RBCs
*most damage caused by host immune response
HPS Clinical Features
Prodromal (3-5d): nonspecific sx’s fever, HA, V/D, myalgia
Cardiopulmonary (24-48h): dyspnea, dry cough, pulmonary edema (pink frothy sputum) circulatory collapse
Covalescent: significant dieresis, improvement/recovery
Diagnosis: RT-PCR for viral RNA, ELISA for IgM and IgG Abs against Hantavitus
Pontiac Fever
Organism: Legionella
Patient: immunocompetent
ROS: mild flu-like sx’s
*self-limiting (so it resolves after about 1 wk)
Melioidosis
Aka Whitemore’s Dz
Organism: Burkholderia pseudomallei
Geography: SE Asia and Australia
- G-ve rod, motile, aerobic
- Facultative intracellular, non spore forming
Transmission: broken skin w/ exposure to soil and fresh water
Hemophilia influenzae Epiglottitis
ROS: enlarged epiglottis shows the “thumb sign” on X-ray, aryepiglottic folds thickening
IgA Protease carriers
NASH: Neisseria (IgA protease) Strep pneumo H. influenzae *the enzyme cleaves IgA at the hinge region
H. Influenzae Clinical Syndromes
EMOP:
- epiglottitis (thumb sign on X-ray)
- meningitis
- otitis media
- pneumonia
Histoplasmosis capsulatum biopsy finding
Yeasts packed inside alveolar macrophages
Ornithosis Clinical Features
ROS: constitutional (fever, HA, chills, myalgia) nonproductive cough and consolidation
*Look for prominent systemic involvement (CNS - encephalitis, GI - N/V/D, other - hepatosplenomegaly)
Diagnosis: serology
Coccidioidomycosis
ROS: self-limited flu-like illness, in immunocompromised can disseminate
Seasonality: late summer, early fall
C. neoformans Pneumonia
ROS: atypical pneumonia
Diagnosis: India Ink stain, latex particle agglutination
Pseudomonas aeruginosa Virulence
Huge capsule (slime layer)
Exotoxins A: ADP-ribosylates eEF-2 target is the liver
Elastase: destroys bv walls
Hantavirus Features
RNA, lipid envelope w/ 2 major glycoproteins (for attachment)
Sin Nombre Virus (SNV) - commonest cause of Hantavirus Pulmonary Syndrome (HPS)
Geography: west of MS river
Blastomycosis
ROS: productive cough, CP, fever; also skin lesions on exposed skin
Investigation: KOH
Histoplasma capsulatum
Dimorphic, facultative intracellular Tissue form: yeasts w/ halos in phagocytes
Environment form: septate hyphae w/ microconidia and tubercular macroconidia
Geography: MS and OH river valleys
Exposure: bat roost or chicken coops (soil w/ increased Nitrogen content)
Ornithosis Course
Spreads to RES producing necrosis, seeded in lung through blood causing lymphocytic inflammation in alveoli
ROS: edema, thickening of alveolar wall, infiltration of macrophages, necrosis and occasional hemorrhages
Cutaneous Diphtheria
ROS: papule dev on skin and progresses to non-healing ulcer, systemic sx’s can dev
Mycoplasma pneumoniae Atypical Pneumonia
Most common form of atypical pneumonia in young adults
