Exam 4 Flashcards
Respiratory illness can be caused by avian influenza. True / False
- True, does not have human-human transmission
What is nontypeable H. influenzae?
- Means it contains no capsule
Diseases cause by chlamydophila pneumoniae
- Pneumonia: more severe infections involve only one lung lobe, difficult to differentiate from atypical pneumonias (mycoplasma pneumoniae, legionella pneumphila and resp viruses). Possibly involved with atherosclerosis - Bronchitis and sinusitis
Complications of pneumonia
1.) Pleural effusion: excess fluid in pleural cavity, limits expansion of lung 2.) Hematologic: anemia, DIC, thrombocytopenia 3.) Low po2, weight loss, muscle atrophy, bronchiectasis (dilation of bronchi/oles d/t muscle/elastic tissue damage)
Streptococcal pharyngitis. Symptoms, causative agent, lab tests, pathogenesis, treatment, vaccination?
- Symptoms: Redness of throat, patches of adhering pus, scattered tiny hemorrhages, fever - Agent = S. pyogenes (Lancefield = group A) - Lab tests = beta-hemolytic, catalase negative - Pathogenesis = a.) M-protein: antiphagocytic and essential for virulence b.) Capsule: in some strains that inhibits phagocytosis (explains severity of some presentations) c.) SPE (streptococcal pyrogenic exotoxins): these are super antigens (9 of them) that cause fever, rash, TC proliferation and B-cell suppression - Treatment: most cases will recover in 7 days, but treatment with penicillin or macrolide (erythromycin or azithromycin) - Vaccine: not available
SARS Coronavirus. Diseases caused, symptoms, transmission
- Diseases: SARS (severe acute respiratory distress) – no cases since 2004, pneumonia - Symptoms: fever, malaise, myalgia, dry cough, SOB, diarrhea, abnormal liver function, lymphopenia - Transmission: fecal-oral, close contact and aerosolized
What slows down the mucociliary escalator and predisposes individuals to RT infections?
- Viral infections - Smoke - Alcohol - Narcotics
Candida (C. albicans primarily). Morphology of fungi, source, disease(s) caused and presentation, risk factors for disease, diagnosis, treatment?
- Morphology: dimorphic, existing in both yeast and hyphal forms. Yeast in normal flora, hyphal forms in tissue when in disease-state - Source: normal flora, in food and on fomites - Diseases caused/presentation: 1.) Oral candidiasis (thrush): diffuse erythema and white patches in mouth, sometimes into esophagus (in immunosuppressed individuals) 2.) Other brain, blood and urogenital infections (discussed later) - Risk factors: infants, adults on steroids, antineoplastics and abx, also AIDS and other immunosuppressed individuals - Diagnosis: observation of budding yeast and hyphal structures in tissue - Tx: mouth washes or lozenges containing nystatin and azole compounds
India ink is used for diagnosis of what microorganism?
- Crytococcus neoformans
Zygomycetes (rhizopus, absidia, mucor). Morphology of fungi, source, disease(s) caused and presentation, risk factors for disease, diagnosis, treatment?
- Morphology: non-septated hyphae, sporangia with sporangiospores - Source: soil, vegetation, food, ubiquitous - Diseases caused: 1.) Rhinocerebral zygomycosis: infection originates in sinus via inhalation of spores and extends into nose, hard palate, eye and brain in some cases. Symptoms initially include nasal congestion, blood-tinged rhinorrhea, tender sinuses, headache and fever. Progresses to facial and periorbital edema and visual disturbances. Can further progress to brain resulting in AMS, coma and death 2.) Lungs , skin and GI infections in immunosuppressed or burn victims where traumatic inoculation has occurred. GI infections in neonates and premature infants seen too - Risk factors: immunosuppressed, diabetics, burn-victims (rare in healthy individuals) - Diagnosis: broad aseptate hyphae, branching at 90 degree angles in material - Tx: amphotericin B
Definition of pneumonia
- Inflammation of lung parenchyma with fluid accumulation in the alveoli which blocks effective gas exchange
Klebsiella pneumoniae pneumonia. Lab tests, clinical presentation, pathogenesis/virulence factors, treatment/resistance, vaccine
- Lab tests: gram neg rod, capsule mucoid colonies, oxidase negative - Presentation: lobar pneumonia, bloody currant jelly sputum (foul-smelling as facultative anaerobe) - Pathogenesis: necrosis and abscess formation from LPS and capsule - Treatment: Aminoglycoside + beta-lactam (gentamycin/cephalexin + tobramycine/ampicillin). ESBL (extended-spectrum beta-lactamase) resistance strains are problematic to treat - No vaccine
Mycobacterium tuberculosis. Transmission, TB symptoms with active TB, diagnosis/lab tests, treatment, vaccine, risk factors,
- Transmission: respiratory aerosol droplets - Symptoms: gradual onset, fatigue, weight loss, weakness, fever, night sweats, chest pain, dyspnea, cough is absent or mild with scant sputum can become sever with yellow/green/blood-streaked sputum - Pathogenesis: Mtb inhaled as droplet into lungs, enters alveoli, taken up with alveolar macrophages, lymphocytes recruited to site, Mtb evasion of killing leads to granuloma formation and infection is walled off by macrophages from surrounding tissue. T and NK cells surround caseous necrotic granuloma mass and prevent spread in latent infections. In active/reactivation, Mtbs are actively dividing and increase inflammation and tissue damage. In disseminated cases, alveolar macrophages migrate to hilar LNs. Pathology of TB is consequence of CMIs response – when adequately controlled granulomas form and disease process halted, when inadequate, TB is active or becomes reactivated - Diagnostics: 1.) Latent TB: Ghon focus, which is lung lesion containing live Mtb seen on CXR as it calcifies or Ghon complex, which is calcified lesion in affected hilar lymph 2.) Active/reactivation TB: CXR shows focal infiltration with cavitation (d/t granuloma breaking apart) often in apical posterior segment of upper lobes of either lungs. 3.) Mantoux/Tuberculin skin test: intradermal injection of proteins derived from cell envelope – positive in infected individuals and always in BCG-vaccinated individuals 4.) IFN-gamma release assay: measure IFN-gamma in whole blood when stimulated with Mtb antigens, means T cells were previously sensitized. Use for pts vaccinated with BCG 5.) Lab: acid-fast staining, PCR, Culture (slow) - Treatment: 4 drug cocktail (isoniazid, ethambutol, pyrazinamide and rifampin) give for 2 months followed by 26 months of isoniazid and rifampin. D/t side effects of isoniazid, concern for compliance - Vaccine: BCG-vaccine using bovis species, not protective - Risk factors: primary TB infections greater in HIV population, also 200-300 times more likely for reactivation TB if latently infected
Causative agents of fungal oral cavity infections?
- Candida, primarily candida albicans
8 yo male involved in accident at home while playing in basement near natural gas furnace and incurs partial thickness burns to 20% of body. In hospital, he requires intubation and mechanical ventilation because of inhalation injury. Pt develops symtoms c/w typical pneumonia. CXR shows lobal pattern of consolidation. Sputum reveals G- rod, which is oxidase positive and negative for lactose fermentation. Which of the following is best choice for treatment? A. Ticarcillin and aminoglycoside B. Aminoglycoside C. Rifampin and aminoglycoside D. Isoniazid, ethambutol, pyrazinamide, rifampin E. No treatment, infection will spontaneously resolve
- Causative agent is Pseudomonas aeruginosa, which is G-neg rod, oxidase positive and obligate aerobe. Causes infections in burn victims among others. Pt has been on vent where this bacterium can be seen preferentially. Option A is best treatment
Most frequent cause of death in CF patients
- Pseudomona aeruginosa respiratory disease
Describe treatment options for influenza. Which virus subtypes are these effective against?
1.) Ion channel blockers: amantadine and rimantadine - Block M2 ion channels in influenza A viruses, currently resistant to these drugs, so not recommended for use by CDC 2.) Neuraminidase inhibitors: zanamivir (relenza) PO inhalation, oseltamivir (tamiflu) PO, peramivir (Rapivab) - inhibits virion release and spread and effective against influenza A and B - must be given in first 48 hours to reduce disease and symptoms
How to distinguish between Chlamydophila pneumoniae and Mycoplasma pneumoniae clinically?
- Symptomatology similar mycoplasma pneumoniae, however small gram-negative, obligate intracellular pathogen via lab results. Treatment is same
URT tissues that are sterile?
- Mastoid air cells - Middle ear - Sinuses - Trachea - Bronchi and bronchioles - Alveoli - Conjunctiva (typically, but d/t location it is common to find microorganisms, which land and don’t stay)
Most common cause of common cold? Other causes?
- Rhinovirus - Non-SARS coronavirus, adenovirus and coxsackieviruses - Also, influenza (B and C), RSV and parainfluenza
How is antigenic drift made possible?
- Reassortment in another species
Normal flora of nose/nares
- Staph epidermidis - Staph aureus - Corynebacterium
How is the influenza virus vaccine produced?
1.) Classic method: in embryonated chicken eggs 2.) Initial production in eggs, then production in mammalian cells (rapid, less egg protein carried over, but ini) 3.) Baculovirus expression vector: baculovirus engineered to express hemagluttinin protein (rapid, egg-free)
Staph aureus pneumonia. Lab tests, pathogenesis/virulence factors, treatment including resistance, vaccine?
- Lab tests: G+ cocci in clusters, catalase pos, coagulase positive - Pathogenesis: a.) Exotoxins including TSST-1 b.) Coagulase: clots blood c.) Protein-A binds Fc portion of ab d.) Panton-Valentine leukocidin (PVL) implicated in cases of necrotizing pneumonia, it is a pore-forming toxin - Treatment: beta-lactams (penicillins, cephalosporins) if sensitive. MRSA is resistant to all beta-lactams. Requires treatment with linezolid (50S inhibitor) or vancomycin - No vaccine yet
What comprises the LRT tract where infections can arise?
- Trachea, bronchi, bronchioles, lungs and alveoli
If a patient presents with scarlet fever, what are symptoms to have preceded this and what is the causative agent?
- Strep throat symptoms: fever, redness throat, pus in post pharynx, hemorrhages to pharynx - Agent = S. Pyogenes
Causative bacterial agents of otitis media and sinusitis
- H. influenzae and Strep pneumoniae (same as conjunctivitis) and Moraxella catarrhalis - Chlamydophila pneumoniae can cause sinusitis too
Most common cause of bronchiolitis and pneumonia in children less than 1 years old?
- RSV
Other mycobacterial infections similar to mycobacterium tuberculosis
- Non-tuberculous mycobacteria: 1.) Mycobacterium avium-intracellulare: complex of severe mycobacteria, immunocompromised pts or those with lung disease present with infection resembling TB 2.) Mycobacterium kansasii: commonly in elderly and COPD pts, this is a chronic granulomatous pulmonary disease • work-up and treatment is similar to Mtb
Causative agents of fungal lung infections?
- Histoplasma capsulatum* - Blastomyces dermatitidis* - Paracoccidioides brasiliensis* - Coccidioides immitis* - Cryptococcus neoformans (encapsulated) - Pneumocystis jiroveci (previously carinii) - Aspergillus (fumigatus and flavus) * dimorphic
Since most cases of strep throat resolve on their own, why is it necessary to treat? How can this occur?
- Strep pyogenes can lead to: 1.) Scarlet fever: result of SPE release 2.) Acute rheumatic fever: cross rxn by immune system to our own tissues including heart leading to arrhythmias 3.) Necrotizing fasciitis: result of SPE release 4.) Acute glomerulonephritis: 1-4 weeks after strep pharyngitis or 3-6 weeks after strep. Pyogenes skin infection – d/t antigen-ab complexes destroying glomeruli
Non-SARS coronavirus. Disease caused, transmission, pathogenesis, treatment, vaccine?
- Disease: common cold - Transmission: large droplets, outbreaks common in spring and winter, infections common in infants and children - Pathogenesis: replicate in epithelial cells of respiratory tract (upper) in cooler temps, enveloped virus - Treatment: meds to alleviate symptoms - No vaccine, reinfections occur despite previous infection
20 yo male with fever, cough, swollen LNs 10 days after exploring cave with numerous bat-roosting sites. CXR pattern similar to primary TB, tuberculin test negative. Sputum yielded mycelial growth when incubated at room temp. Isolates show abundant tuberculate macroconidia. What is the most likely causative agent and diagnosis?
- Histoplasmosa capsulatum causing histoplasmosis
Most common causative agents of hospital acquired pneumonia
- Gram negatives (more commonly): Pseudomonas aeruginosa, E. coli, Klebsiella pneumoniae, acinetobacter spp., H. influenzae - Gram pos: S. aureus, S. pneumoniae
Replication cycle of Chlamydophila pneumoniae
1.) Elementary body (EB) attaches to and enters cell 2.) EB reorganizes to a reticulate body (RB) 3.) RB undergoes several rounds of binary fission 4.) RBs reorganize into EBs 5.) EBs emerge and begin cycle with newly susceptible cells
Pseudomonas aeruginosa pneumonia. Lab tests, source, pathogenesis/virulence factors, treatment, vaccine, risks?
- Lab tests: G- rods, obligate aerobe oxidase positive, blue/yellow-green pigments in culture that is grape smelling - Source: water with minimal nutrients, hand soaps, dilute antiseptics, humidifiers, resp sink traps and contaminated aerosols - Pathogenesis: a.) Toxin A: halts protein synthesis via ADP ribosylation of EF-2 b.) Leukocidin: pore forming toxin targeting leukocytes c.) PLC: membrane disruption d.) Capsule: anti-phagocytic e.) Pyocyanin: blue compound toxic to host f.) Pyoverdin: fluorescent green iron uptake protein - Treatment: Antipseudomonal penicillins (Ticarcillin / piperacillin) + aminoglycoside (amikacin, gentamycin or tobramycin) - No vaccine - Risks: noteworthy for causing infections associated with extensive burns, CF patients and pts on cytotoxic drugs. Humidifiers, respirators and sink traps have been problem resulting in infected aerosols
Which influenza virus is/are much more severe?
- Types A and B, A is often severe d/t antigenic changes occurring from drift and shift.
Diseases causes by chlamydia trachomatis. Pathogenesis
- Trachoma: conjunctival infection that progressively causes conjunctiva to become scarred and eyelids to turn inward, abrading the cornea leading to vision loss - Adult inclusion conjunctivitis: cause by serovars associated with genital infections, similar to other bacterial conjunctivitis, corneal scarring as seen in trachoma is less common - Neonatal conjunctivitis: neonates exposed to bacterium at birth, symptoms 5-12 days after, untreated have risk for pneumonia from bacteria - Infant pneumonia: rhinitis initially, then bronchitis with dry cough, afebrile - Urogenital infections (discussed later) - Pathogenesis: gain access to cells by minute abrasions or laceractions, direct destruction of host cells during replication and host inflammatory response leads to tissue destruction. Worse immune response with subsequent infection
Aspiration pneumonia is commonly associated with what patient groups?
- Alcoholics, coma patients and stroke patients
Causative agents of laryngitis, tracheitis and epiglottitis
- Most likely viral, but could be bacterial: group A strep (strep. Pyogenes), H. influenzae and staph aureus
Bacterium associated with parrots/parakeets
- Chlamydophila psittaci causes pneumonia
When should influenza anti-viral medication be used prophylactically?
1.) Those at risk for complications who have been vaccinated after flu season has begun 2.) Non-immune health care workers and families who care for high risk pts 3.) When there is poor match between vaccine strain and circulating strains
Compare: community acquired pneumonia vs hospital acquired pneumonia
- CAP: any pneumonia not acquired in a healthcare setting - HAP: any pneumonia acquired in a healthcare setting, associated highly with immunocompromised, those using ventilator, frequently gram-negative MDR bacteria
Diseases caused by pseudomonas aeruginosa
- Pneumonia, septicemia, UTIs, wound infections, meningitis in pts with extensive burns, folliculitis, ocular infections, endocarditis and osteomyelitis in IV drug users, ecthyma gangrenosum lesions in sepsis patients
How are influenza viruses named?
- A/Texas/1/77(H3N2) - A=serotype - Texas=location of isolation - 1=isolate number - 77=year it was isolated - H=hemagluttinin subtype - N=neuraminidase subtype
Alpha-hemolysis typically indicates what pathogen?
- Streptococcus pneumoniae is the first thing one should think - Could also be viridians group (S. mutans/mitis/milleri and salivarius)
Legionella pneumophila. Disease caused, presentation, lab tests, pathogenesis/virulence factors, source, treatment, vaccine?
- Disease: Legionnaire’s disease – severe toxic pneumonia and Pontiac fever (acute non-fatal respiratory disease similar to acute influenza) - Presentation of Legionnaire’s: myalgias, headache, rapid rising fever, dry cough that may become productive, chills, pleurisy, vomiting, diarrhea, confusion and delirium – ill over 3-6 days and results in shock, respiratory failure or both, elevated WBCs seen - Lab tests: G neg facultative intracellular parasite – coccobaccili intracellularly, pleomorphic extracellularly, culture and detect via antibody fluorescence or PCR - Pathogenesis: 1.) Pili/flagella: targets and attaches to alveolar macrophage, enters in endocytic vacuole 2.) Hijacks cell: injects bacterial proteins into cytosol, prevents fusion with lysosome, recruits ribosome, mitochondria and ER to vacuole now called LCV (Legionella-containing vacuole) and replicates in high numbers and starts process again after lysis of host. This leads to inflammation, lung necrosis and systemic toxicity in host - Source: high humidity – therefore freshwater lakes, streams, ground water, potting soil – mainly parasite of amoeba – in human outbreaks: cooling towers/AC units in hotels, factories, hospitals, respiratory devices - Treatment: NOT beta-lactams as many produce beta-lactamases, treat with macrolide or fluoroquinolone - No vaccine
Strep pneumoniae. Lab tests, pathogenesis/virulence factors, presentation of pneumonia/sputum, treatment, vaccine?
- Lab tests: alpha-hemolytic, catalase negative, gram poss diplococci, bile solubility pos (no growth), optochin sensitive, urine test positive for polysaccharide capsule - Pathogenesis: a.) Surface adhesins: colonize pharynx b.) IgA protease: cleaves IgA and prevents clearance c.) Pneumolysin: pore forming toxin, colonization, invasion, complement and inflammation activator d.) Teichoic acid and peptidoglycan: inflammation e.) Polysaccharide capsule: antiphagocytic - Presentation: cough, dyspnea, severe pleuritic chest pain, crackles, rust-colored sputum, rhinorrhea, spiking fevers with chills, poor oxygenation - Treatment: penicillins, macrolides, more serious cases require azithromycin and cephalosporin - Vaccine: 23-valent pneumococcal polysaccharide OR 13-valent pneumococcal-diphtheria conjugated toxoid vaccine
Diptheria. Symptoms, causative agent, lab tests, pathogenesis, treatment, vaccination?
- Symptoms: mild sore throat, slight fever, high fatigue/malaise, neck swelling, whitish gray membrane over throat, tonsils and nasal cavity - Agent: Corynebacterium diphtheria - Lab tests: Chinese letter growth in culture - Pathogenesis: membrane (represents clotted blood, epithelial cells of mucous membrane and leukocyte infiltrate), diphtheria exotoxin (lysogenized by bacteriophage) absorbed by blood stream in inactive forms – B binds receptor, A (true enzyme) inactivates EF-2 via ADP ribosylation stopping protein synthesis and inducing cell death – damage to heart, kidneys and nerve cells, which have B subunit receptor - Treatment: antiserum against toxin, erythromycin and penicillin - Vaccination: TDaP or DPT (toxoid vaccine)
Rhinovirus. Disease caused, transmission, pathogenesis, treatment, vaccine?
- Disease: common cold - Transmission: respiratory secretions, direct contact with these and fomites, low inoculum needed - Pathogenesis: attaches and infects nasal epithelium, cell damage and clear fluid outpours from lamina propria, damaged cells spreads infection - Treatment: meds to alleviate symptoms (antihistamines, decongestants) - No vaccine, previous infection only creates immunity to that serotype – 100+ serotypes around
Typical drug treatment of gram-negative pneumonias
- Aminoglycoside + beta-lactam (gentamycin/cephalexin + tobramycine/ampicillin)
What is miliary TB?
- Miliary TB is disseminated TB / extrapulmonary TB infection where Mtb has spread and granuloma formation has occurred in any other site in body
Which adenovirus serotypes are seen with common cold? GI infection?
- 1, 2 and 5 - GI infection = 40 or 41
Coccidioides immitis and posadasii. Morphology of fungi, source, disease(s) caused and presentation, diagnosis, treatment?
- Morphology: dimporphic fungus, as molds with hyphae in environment (with arthroconidia that are easily airborne) and yeast in tissues during infection with spherules (multinucleated structure) - Source: Western hemisphere, endemic in San Joaquin Valley of CA and in S. Arizona, follows drought-rain-drought pattern and fungal elements present in blowing dust - Diseases caused/presentation: 1.) Pulmonary coccidioidomycosis: 60% of individuals asymptomatic, presents as mild-moderate influenza like syndrome with fever, cough, night sweats, malaise, chest pain. Can progress to chronic pulmonary dz 2.) Disseminated coccidioidomycosis: rare, develops within one year of pulmonary infection. Infection of bones, joints, skin and CNS. “Desert rheumatism”-fever, nodules and arthralgia. 3.) Coccidial meningitis: (2nd leading cause of fungal meningitis) – gradual onset with increasing HA, fever, stiff neck and other neuro signs. - Diagnosis: observation of distinct spherule forms of yeast - Tx: azole and amphotericin B
Aspergillus fumigatus and flavus. Morphology of fungi, disease(s) caused and presentation, risk factors for disease, diagnosis, treatment?
- Morphology: true mold in both environment and tissue, septated hyphae - Disease(s) caused and presentation: 1.) Pulmonary aspergillosis: infection through inhalation of conidia, hyphal growth causes pathology. Conidia colonize pre-existing lung lesions, typical infect unilaterally. Aspergillomas / “fungus balls” can be seen on x-ray. Hyphae can penetrate blood vessels. Symptoms: fever, hemoptysis and chest pain 2.) Disseminated aspergillosis: fungal hyphae invade into lumen and walls of BVs causing thrombosis, infarction and hemorrhage. Can disseminate to GI, brain, liver and kidney. - Risk factors: immune-compromised individuals, rarely pathogenic in normal immune status patients - Diagnosis: observation of septated hyphae with V/A-shaped branches at 45 degree angle (think A for aspergillus) - Tx: Azoles, echinocandins, amphotericin B, surgical removal of aspergillomas
Describe the general symptomatology associated with bacterial pneumonias
- Fever, malaise, cough, pleuritic chest pain, dyspnea and potentially sputum production
How to distinguish between viral and bacterial conjunctivitis clinically?
- typically by amount of purulent discharge, more pus = bacterial - minimal swelling in viral conjunctivitis
Coxsackievirus. Diseases caused, transmission, pathogenesis, treatment, vaccine?
- Diseases: common cold, hand-foot and mouth (fever, vesicular lesion on palms and soles and oral areas), herpangina (fever, small vesicles on soft palate that rupture and form ulcers), rarely meningitis and encephalitis - Transmission: fecal-oral (enterovirus, survives in GI tract) - Treatment: alleviation of symptoms, recovery in a couple of weeks - No vaccine
Respiratory illness can be caused by CMV, measles and VZV?
- True - In measles and VZV, skin lesions are seen
Symptoms of streptococcal pharyngitis
- Redness of throat, patches of adhering pus, scattered tiny hemorrhages, fever
Bacterial agent of pharyngitis? What are the blood agar lab tests and catalase test results?
- Streptococcus pyogenes - Group A, beta-hemolytic, catalase negative
Which influenza virus only infects humans?
- Influenza type B
Haemophilus influenzae. Diseases caused, lab tests, transmission, pathogenesis/virulence factors, treatment, vaccine?
- Diseases caused: laryngitis, tracheitis, epiglottitis, conjunctivitis, sinusitis, otitis media, pneumonia/tracheobronchitis, meningitis, purpuric fever and bacteremia - Lab tests: G- coccobacilli, requires chocolate agar for growth (Factor X: hemin and factor V: NAD), can contain polysaccharide capsule - Transmission: droplets or secretions - Pathogenesis/virulence factors: LPS, IgA protease, typed strains contain PRP (polysaccharide-capsule polyribosylribitol phosphate) which is antiphagocytic - Treatment: mortality greater than 90% if untreated (septicemia, meningitis), treat with broad-spectrum cephalosporin or amoxicillin in less severe cases - Vaccine: HiB (type B only) – conjugate vaccine (PRP capsule linked to protein carrier)
Diseases caused by streptococcus pneumoniae. Is there vaccine for this?
- sinusitis, otitis media, lobar pneumonia, meningitis - vaccine = pneumovax
Adenovirus. Diseases caused, transmission, pathogenesis, treatment, vaccine?
- Diseases: common cold and pharyngoconjunctival fever (conjunctivitis, pharyngitis and fever), respiratory infections (croup, bronchiolitis, pneumonia), GI infections (with serotypes 40 and 41) - Transmission: oral, droplet inhalation, conjunctiva, non-enveloped therefore stable in environment - Pathogenesis: only dsDNA virus that causes common cold, fibers proteins protrude from capsid and are used for attachment, toxic to cells, replicates in epithelial cells causing tissue damage, can enter lymphoid tissue and shed virus for up to 18 months following infection - Treatment: alleviation of symptoms - Vaccine to serotypes 4 and 7 for military recruits, immunity only serotype specific
List major pathogens for pneumonia (typical and atypical)
1.) Typical - Gram pos: Streptococcus pneumoniae, Staphylococcus aureus - Gram neg: Klebsiella pneumoniae, Pseudomonas aeruginosa = most common 2.) Atypical (walking pneumonia) - Mycoplasma pneumoniae - Chlamydophila pneumoniae - Legionella pneumophila (toxic pneumonia) * also chlamydophila psittaci and coxiella burnetii
Pt presents to clinic in summer and after work-up is diagnosed with common cold of viral etiology. What is the most likely causative agent?
- Adenovirus. No seasonal pattern of disease
Causative agents of bacterial bronchitis?
- Mycoplasma pneumoniae - Bordatella pertussis
Causative agent of tuberculosis
- Mycobacterium tuberculosis
Causative agents of fungal sinus infections?
- Zygomycete class of organism, primary rhizopus, absidia and mucor genera
Conjunctivitis (pinkeye). Symptoms, causative bacterial agents, pathogenesis, treatment and prevention
- Symptoms: eyelid swelling, conjunctival redness and edema, sensitivity to light, purulent discharge - Causative agents: Most common = H. influenzae and Strep. Pneumoniae. Also less frequently = Moraxella lacunata, enterobacteria and N. gonorrhoeae - Pathogenesis: inflammation, resistance to lysozyme - Prevention: removed from school/daycare/work, washing hands, no rubbing eyes - Treatment: topical gentamicin or cipro eye drops, both common bacterial can be resistant
How to differentiate from diphtheria and strep throat from clinically?
- Whitish gray membrane over throat, tonsils and nasal cavity in diphtheria, also neck swelling is dramatic
Why can viral respiratory tract infections predispose patients to bacterial infections?
1.) Interrupt the mucociliary escalator 2.) Weaken the immune system
Symptoms of common cold
- rhinitis (inflammation of nasal mucosa), pharyngitis (sore throat), no high fever or respiratory distress, no LRT involvement
Clinical characteristics of gram-negative pneumonias
- Pt has underlying disease - Symptoms: purulent sputum in addition to typical symptoms, anaerobic bacteria produce foul smelling sputum - Any lobe affected - ¼ of pts have pleural effusion - Abx resistance BIG problem - 20% of pts have positive blood cultures - Treatment: multidrug synergistic treatment
What is pneumonia? Symptoms of influenza vs primary influenza virus pneumonia vs bacterial influenza-associated pneumonia?
- Inflammation of lung parenchyma leading to abnormal gas exchange - Influenza symptoms: fever, chills, cough, fatigue/malaise, myalgia - Viral Pneumonia: above + increased cough, tachypnea, dyspnea, respiratory distress, hypoxia - Bacterial Pneumonia: influenza symptoms lessen, then increased cough, return of fever and respiratory distress
Histoplasma capsulatum. Morphology of fungi, source, disease(s) caused and presentation, risk factors for disease, diagnosis, treatment?
- Morphology: dimorphic, as molds with hyphae in environment and yeast in tissues during infection, characteristic tuberculate round bumpy appearance of macroconidia (spores) - Source: N American in MS and OH River valleys, also in central American. Humid climate commonly found in soil containing bird and bat droppings - Diseases caused/presentation: 1.) Pulmonary histoplasmosis (aka Darling’s dz, cave dwellers or spelunker’s dz): inhaled spores phagocytosed by pulmonary macrophages and convert into yeast form, replicated within macrophages. Mild flu-like illness with dry cough, fever and fatigue. Pulmonary lesions in asymptomatic individuals previously affected can be seen. 2.) Chronic pulmonary and disseminated histoplasmosis: seen in immune-compromised individuals. Individuals experience symptoms similar to TB: fever, night sweats, anorexia, weight loss, fatigue and resp symptoms. Present with organomegaly d/t spread through reticuloendothelial system - Risk factors: immunocompromised - Diagnosis: yeast form (characteristic tuberculate round bump) in clinical samples - Tx: Amphotericin B. Immunosuppressed require lifelong azole treatment
Empiric therapy for atypical pneumonia
- Tetracycline and erythromycin
Most common cause of typical bacterial pneumonia? Atypical bacterial pneumonia?
- Typical = streptococcus pneumoniae (50% of HAP, 36% of CAP) - Atypical = mycoplasma pneumoniae
Blood agar grouping of streptococci species
- Alpha=partial hemolysis (green coloration): S. pneumoniae and viridians (differentiate these two groupings by optochin – viridans are resistant, pneumoniae are sensitive) - Beta=complete hemolysis (clear zone): S. pyogenes and S. galactiae - Gamma=no hemolysis: S. bovis
Colds are most typically from viruses – true / false
- True
Results of sputum analysis that indicates pneumonia
- Greater than 25 PMNs - Less than 10 epithelial cells per 100x field
How can x-ray be helpful in differentiating between bacterial pneumonia and viral pneumonia?
- Bacterial pneumonia will typically show consolidation, while viral shows interstitial pattern
Most pathogenic H. influenzae serotype
- B (capsular)
Are crackles (crepitations/rales) more or less common for typical vs atypical pneumonias?
- More common for typical pneumonias
Blastomyces dermatitidis. Morphology of fungi, source, disease(s) caused and presentation, diagnosis, treatment?
- Morphology: dimorphic, as molds with hyphae in environment and yeast in tissues during infection, with characteristic large size and very thick cell wall with broad-bases in budding - Source: moist soil, endemic in OH and MS river valley and in MO and AR river basins - Diseases caused/presentation: 1.) Blastomycosis (aka Gilchrist’s dz, Chicago’s dz or N. American blastomycosis): primarily a pulmonary dz with potential to disseminate causing ulcerative lesions of skin, bone and UG tract. Yeast survive in macrophages, which allows dissemination. Acute presentation (mimic bacterial pneumonia): cough, fever, chills, arthralgia, myalgia, chest pain, sputum. Chronic (mimic of TB): cough, fever, night sweats, weight loss, sputum. 2.) Disseminated blastomycosis: skin lesions (ulcerative and disfiguring, painless), bone infections (granuloma and necrosis), prostate infection - Diagnosis: distinct thick cell walled large yeast with broad-bases in budding in biopsy material - Tx: amphotericin B and azoles
Cryptococcus neoformans. Morphology of fungi, source, disease(s) caused and presentation, risk factors for disease, diagnosis, treatment?
- Morphology: encapsulated yeast - Source: abundant in soil contaminated with bird (mostly pigeon) dropping - Disease(s) caused and presentation: 1.) Pulmonary disease: mild influenza like illness with little sputum production and damage to lung 2.) Disseminated disease: to skin and bone 3.) Fungal meningitis: #1 leading cause. Develops gradually with intermittent bouts of HAs, irritability, dizziness and other neuro signs – symptoms over weeks or months. - Risk factors: risk for meningitis = AIDS/immunocompromised pts - Diagnosis: India ink stain reveals encapsulated yeast from clinical material (only positive 50% of time), requires more sensitive antigen testing nowadays - Treatment: Amphotericin B and 5-fluorcytosine or fluconazole, prophylaxis treatment in those with risk factors
Consequences of SPE
1.) Scarlet fever: redness of tongue, white coating of tongue 2.) Toxic shock: fever, joint pain, chest pain, rash, arrhythmias, skin nodules, jerky movements 3.) Necrotizing fasciitis: skin infection
77 yo female underwent knee replacement surgery recently. Surgical complication has required pt to be on mechanical vent to assist with breathing for last two months. Pt spiked abrupt fever of 41 degC, coughing up foul smelling sputum and complains that it is painful to breathe. Lung aspirate culture reveals gram-neg rod, oxidase negative, grows anaerobically, forms large mucoid colonies. Which of the following is a virulence factor produced by pathogen causing this infection? A. Panton-valentine leukocidin B. Capsule C. Pyoverdin D. Lipoarabinomannin E. Protein A
- Sounds like aspiration pneumonia and you would think about anaerobic bacteria that cause pneumonia. This is a gram-neg from hospital. Most likely gram neg offenders in this setting are Klebsiella pneumonia and pseudomonas aeruginosa. Large mucoid colonies are seen in Klebsiella pneumonia. Pathogenesis from this bacterium is d/t LPS and capsule. Option B is correct.
Developmental cycle of chlamydiaceae family of bacteria (chlamydia spp and chlamydophila)
- Infectious elementary body (EBs - metabolically inactive) attaches to susceptible host and are phagocytosed. Once inside, they inhibit phagolysosome fusion. They reorganize into larger more metabolically active reticulate bodies (RBs) (non-infectious) and utilize host cell ATP
Bronchiolitis. Causative agent, symptoms, transmission, treatment, vaccine
- Causative agent: RSV - Symptoms: expiratory wheezing, nasal flaring, air trapping, retractions, variable fever - Transmission: inhalation of large droplets, direct contact with respiratory secretions – season varies by region - Treatment: aerosolized ribavirin (guanosine analogue that inhibits nucleotide biosynthesis and mRNA capping, also promotes hypermutation in genome) indicated for severe RSV infection in premies, patients with chronic lung dz, conginent heart dz and immunocompromised - No vaccine. Prevention in low GA births, young with chronic lung disease is in form of monoclonal anti-RSV antibody (palivizumab) and pooled enriched human anti-RSV antibodies (RSIG)
Differentiate between antigenic shift/drift in influenza virus, what is the epidemiological significance?
- Shift: small changes to H&N by point mutations during replication, changes every 2-3 years and vaccine changes every year to catch these - Drift: large changes to H&N by reassortment with co-infections and the fact that the viruses have segmented genome, risk for pandemics with major changes
Lancefield grouping of disease-causing streptococci species
- Group A: S. pyogenes - Group B: S. agalactiae - Group D: S. bovis
Which is the best way to diagnose TB in pts vaccinated with BCG-vaccine?
- IFN-gamma release assay
Most common bacteria implicated in aspiration pneumonia
- Gram negative bacteria: Klebsiella pneumoniae and Pseudomonas aeruginosa
Distinguish between TB disease states
1.) Primary TB (asymptomatic): droplet containing Mtb are inhaled, enter lungs and travel to alveoli, this is either cleared (not understood) or leads to either of following: 2.) Active TB: in immuno-compromised individuals 3.) Latent TB: in most individuals a.) Reactivation: reactivation upon immuno-compromising event or immuno-senescence. These individuals can be asymptomatic for 2-3 years and still be infectious
Given the following sputums, what is the most likely cause/type of pneumonia: a.) purulent, b.) scant/water/mucoid, c.) rust colored, d.) thick currant jelly, e.) large amount of blood, f.) foul smelling
- a.) typical pneumonia - #1 cause = strep pneumonia - b.) atypical interstitial pneumonia - #1 cause = mycoplasma pneumoniae - c.) strep pneumonia - d.) Klebsiella pneumonia - e.) cavitary TB or lung abscess - f.) anaerobic bacterial pneumonia
46 yo male admitted to hospital with productive cough of purulent sputum, pleuritic chest pain, fever and chills. Medical history of HTN and smoking. Pts temp 40 deg C, breath sounds diminished at right base, but bronchial breath sounds and rales just above the area. WBC elevated. CXR showed right lower lobe consolidation with right pleural effusion. Gram stain shows gram-pos cocci. Which of the following is a component of vaccine that is commonly administered to prevent infection by the most likely causative agent? A. Panton-Valentine leukocidin B. Live-attenuated BCG C. Capsular polysaccharide D. Detoxified pertussis toxin E. Polyribosylribitol phosphate
- Purulent sputum, typical pneumonia symptoms and findings, gram positive cocci = strepcoccus pneumoniae. - Vaccine = 23-valent pneumococcal polysaccharide OR 13-valent pneumococcal-diphtheria conjugated toxoid vaccine, so Option C is correct answer
What composes the URT?
- Conjunctival, nasolacrimal ducts, middle ear, nose, pharynx, sinuses, nasal cavity, larynx and epiglottis
Compare and contrast clinical presentation of typical vs atypical pneumonias in terms of: onset, facies, cough, sputum, temperature of pt, pleurisy, consolidation, WBC count, CXR appearance
1.) Typical: sudden onset, toxic facies, productive cough, purulent/bloody sputum, temp between 103-4, frequent pleurisy, frequent consolidation, elevated WBC with left shift, lobar pattern on CXR 2.) Atypical: gradual onset, well facies, non-productive cough, scant/watery sputum, temp less than 103, rare pleurisy, rare consolidation, normal or elevated WBC, patchy CXR pattern
Structure of mycobacteria
- Weakly gram positive, acid-fast rods with lipid rich cell wall composed of: plasma membrane with proteins, peptidoglycan layer, arabinogalactan, lipoarabinomannan, mycolic acids and associated glycolipids - Acid-fast stains include: Ziehl-Neelsen or Kinyoun stains to identify genus mycobacteria, but not specific species
Bordatella pertussis. Diseases caused, lab tests, presentation, pathogenesis/virulence factors, treatment, vaccine?
- Diseases: bacterial bronchitis (whooping cough) - Lab tests: G- coccobacilli, requires Bordet-Gengou agar, PCR - Presentation: 1.) incubation period (7-10 days): no symptoms 2.) catarrhal (1-2 weeks): rhinorrhea, malaise, fever, sneezing, anorexia ** highest period of communicability/transmission 3.) paroxysmal (2-4 weeks): repetitive cough / whoops, vomiting, leukocytosis 4.) convalescent (3-4 weeks): diminishing cough, secondary complications (pneumonia, seizures, encephalopathy) - Pathogenesis/virulence factors: filamentous hemagglutinin, peractin and fimbae allow bacteria to bind to ciliated epithelial cells, pertussis (AB) toxin increases cAMP levels = increased secretions = paroxysmal cough, LPS and adenylate cyclase present too - Treatment: supportive therapy, macrolides - Vaccine: DTaP (acellular pertussis containing detoxified pertussis toxin, peractin and filamentous hemagglutinin)
Why is previous illness with strep pyogenes not protective and vaccination against difficult/impractical?
- 80 serotypes of M protein (essential virulence factor)
Complications from common cold
- Otitis media - Sinus infection - Exacerbation of asthma (from rhinovirus C)
Mycoplasma pneumoniae. Lab tests, diseases caused, pathogenesis/virulence factors, treatment, vaccine?
- Lab tests: cold agglutinin test (RBCs agglutinate at 4 degC), PCR, serology - Diseases causes: bronchitis, pneumonia, anemia - Pathogenesis/virulence factors: P1 adhesin binds to base of cilia leading to ciliostasis and defect in mucociliary escalator and loss of mucociliary clearance. Anemia is result of IgM cross reacting with RBCs - Treatment: tetracycline and macrolide (erythromycin), NOT beta-lactams EVER! - Vaccine: none
Influenza. Symptoms, causative agent, transmission, pathogenesis, complications, risk factors, treatment, vaccine?
- Symptoms: myalgia, HA, fever, chills, cough peaks after 3-5 days, fatigue/malaise - Causative agent: influenza virus A, B and C - Transmission: peak during winter months - Pathogenesis: hemagglutinin attaches to cells, neuraminidase cleaves sialic acid, induces virion release and spread - Complications: primary influenza virus pneumonia (type A) 1-4 days after influenza OR bacterial influenza-associated pneumonia - Risk factors: young children, elderly, pregnant/postpartum women, persons with certain illness (metabolic, asthma, endocrine etc) - Treatment: based on risk factors a.) If none, provide symptomatic care, consider use of antiviral b.) If risks, pts should be treated with antivirals (two classes: ion channel blockers and neuraminidase inhibitors) - Vaccine: three types
Diseases caused by chlamydophila psittaci. Pathogenesis, Risk factors?
- Interstitial pneumonia - Via respiratory tract, bacteria spread to reticuloendothelial cells of liver and spleen where they multiple seeding to lung and other tissue via blood. In lung, cause lymphocytic inflammatory response on alveolar and interstitial spaces - Risk factors: psitaccine bird exposure (parrots, macaws, parakeets)
Antibiotic treatment that targets pseudomonas
- Antipseudomonal penicillins (Ticarcillin / piperacillin) + aminoglycoside (amikacin, gentamycin or tobramycin)
Compare and contrast CXRs between pts with typical and atypical pneumonia
- Typical pneumonia CXR: “lobar pattern” - Atypical pneumonia CXR: “patchy pattern” • not always reliable
Describe the general pathogenesis of bacterial pneumonia
- Bacteria enter into small airways or alveoli, grow in rich environment, express/release virulence factors which damage surrounding area 2. Inflammatory response to bacteria leads to irritation, pain and dyspnea 3. Accumulation of fluid, bacteria, neutrophils and fibrin results
What test differentiates staphlyococcus from streptococcus spp.?
- Catalase. Negative for streptococcus
What type of infections do systemic mycoses most likely start with? Why?
- Pulmonary infections d/t inhalation of fungal elements
Complications of pneumococcus pneumonia
- Bacteremia - Meningitis - Death
Feature in URT that is antipathogenic?
- Mucociliary escalator that comprises the ciliated epithelium. This propels mucous out and away from structures of URT and into esophagus for swallowing
What are the leading causes of fungal meningitis?
- # 1 = Cryptococcus neoformans - #2 = Coccidioides immitis
Beta-lactams are suitable for treating mycoplasma. True / False.
- False, they have no peptidoglycan
Previously healthy middle-aged construction worker who recently worked on demolition project experienced respiratory symptoms. Sputum specimens were neg for bacterial growth. Pt did not respond to antibacterial abx and died before definitive diagnosis was established. Microscopic exam of specimens from granulomatous/suppurative lesions of lung obtained during autopsy revealed presence of large budding yeast cells. Buds were attached to parent cell by broad base. What is the most likely causative agent and diagnosis?
- Thick cell walls with broad base attached to parent cell = Blastomyces dermatitidis causing blastomycosis
3 forms of influenza virus vaccines. Describe each, administration, who is eligible for each and what are the strain compositions
1.) Inactivated influenza vaccines (IIV): formaldehyde-inactivated virus - ID or IM administration (flu-shot) - IM for those older than 6 months including those with chronic medical conditions, ID for 18-64 year old patients - Strains: IM = trivalent or quadrivalent, ID = trivalent 2.) Live attenuated influenza vaccines (LAIV): attenuated virus (flu-mist) - Intranasal administration (flu-mist) - For healthy, non-pregnant persons 2-49 yo - Strains: quadrivalent 3.) Recombinant influenza vaccine (RIV): hemagglutinin protein - IM - For 18-49 age group - Strains: trivalent
Mechanism of action of isoniazid
- inhibits mycolic acid synthesis
Croup (aka laryngotracheobronchitis). Symptoms, causative agents (incl. most common), pathogenesis of most common, transmission of most common, complications, differential dx, treatment, vaccine?
- Symptoms = Fever, distinct “seals-bark” cough, inspiratory stridor, prodrome = nasal discharge, mild cough, pharyngitis (common cold symptoms) - Causative agents: Most commonly = parainfluenza virus (type 1), type 2-3 also (3 causes LRT infection too), also RSV, measles virus, adenovirus, Corynebacterium diphtheriae - Pathogenesis: hemagglutinin to attach to ciliated epithelium of respiratory tract, neuraminidase cleaves sialic acid and allows for virion release and spread - Transmisson: large droplets, direct contact - Complications: hypoxia - Diff Dx: non-infectious causes, bacterial epiglottitis - Treatment: alleviate symptoms, if stridor at rest only, tx with humidified air / hydration, if constant: oxygen, epi and glucocorticoids - Vaccine: none, re-infection less severe
Who are at increased risk for bacterial pneumonias?
- Comorbidities: heart dz, diabetes, lung dz/cancer, immunosuppressed - Age extremes - Smokers, alcoholics, narcotic users, virally infected – these all affect the mucociliary escalator
Paracoccidioides brasiliensis. Morphology of fungi, source, disease(s) caused and presentation, diagnosis, treatment?
- Morphology: dimorphic, as molds with hyphae in environment and yeast in tissues during infection - Source: tropical regions of South and Central America - Diseases caused/presentation: 1.) Pulmonary paracoccidioidomycosis (aka S American blastomycosis): similar to blastomycosis and histoplasmosis 2.) Disseminated paracoccidioidomycosis: chronic cutaneous and mucocutaneous ulcers - Diagnosis: yeast appear as “ship’s wheel” or “Mickey Mouse ears” - Tx: amphotericin B, sulfonamides or azole compounds
Normal flora of nasopharynx
- Strep mutans, mitis, milleri and salivarius - Bacteriodes (only obligate anaerobe in this location) - Flora and pathogenic (seasonal associations): Strep pneumoniae, Haemophilus influenzae, Neisseria meningitides and Moraxella catarrhalis
How to differentiate staph aureus and strep pneumoniae pneumonias in lab?
- Staph aureus is catalase positive
Treatment for chlamydiaceae family infections
- Macrolides, tetracyclines or levofloxacin for 10-14 days
Pneumocystis jiroveci (carinii). Disease(s) caused and presentation, risk factors for disease, diagnosis, treatment?
- single-celled eukaryotic that is similar to protozoa in its cellular/metabolic processes - Disease(s) caused and presentation: 1.) Pneumonia: previously pneumocystis carinii pneumonia (PCP): highly lethal form. Infection through inhalation of cysts. Present with dyspnea, non-productive cough and fever. Develop weakness, tachypnea, and cyanosis. Death from asphyxiation - Risk factors: primarily in immune-compromised - Diagnosis: identification of life cycle stages: trophozoite, sporozoites, cysts from specialized staining, in this case modified silver staining - Tx: trimethoprim-sulfamethoxazole that intereferes with folate synthesis. Prophylactically treat immunosuppressed
