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Micro Ch 18 & 19
URI & LRI
Question | Answer |
---|---|
Identification: (+)ssRNA (infectious). Picornavirus. Pathology: Bronchitis, Common cold | Rhinovirus: naked RNA induces viral protein synthesis in host cell |
Identification: (+)ssRNA, enveloped. Pathology: Colds, bronchitis, SARS Virulence: Binds to ACE2 receptor in lung epithelium Hallmarks: SARS is hallmarked by high fever, dyspnea, and cough. | Coronavirus Treatment: Ribavirin |
Identification: dsDNA, encapsulated Hallmark lesions are small, fluid-filled vesicles. Lies dormant on neuronal roots until conditions are right for re-emergence. | Herpes Simplex virus Treatment: -ciclovir drugs. |
Identification: Enterovirus Pathology: “Common cold” caused by binding to ICAM-1 Hallmarks: “Hand, foot and mouth disease” oropharyngeal vesicles (A16) | Coxsackie virus Treatment: Mostly supportive: Ribavirin (rarely) |
Identification: dsDNA, no envelope Pathology: viral atypical pneumonia, pharyngitis, gastroenteritis, conjunctivitis (depends on serotypes). Hallmarks: Seen in the young and military recruits. | Adenovirus Treatment: Mostly supportive: Ribavirin (rarely) |
dsDNA, enveloped; largest human herpes virus. In immunocompromised (AIDS/bone marrow transplant), can go to eye, liver, GI. Causes large nucleus, cytoplasmic inclusions, interstitial pneumonitis. 2nd leading cause of mental retardation in babies. | Cytomegalovirus (CMV) Treatment: ganciclovir, foscarnet or cidofovir if needed. |
Herpes virus that causes mononucleosis (main cause). “Atypical lymphocytes” demonstrates “heterophil antibodies” to sheep RBCs in “monospot test”. Binds to CD20 and resides in B cells. Infection by saliva exchange “kissing disease” (peak @ 4yo & 16yo). | Epstein-Barr virus (EBV) Very closely linked with Burkitt’s lymphoma in Africans, B-cell lymphoma (“hairy tongue”) in immunocompromised, and nasopharyngeal carcinoma in Asians. |
Identification: ssRNA, Paramyxovirus Pathology: Parotitis, orchitis, pancreatitis, occasional meningitis. Spread by airborne droplet, infecting salivary glands. Peak 5-14 yo. | Mumps virus Treatment: Prevention by MMR vaccine |
Gram(+) cocci grows in chains. Blood agar beta-hemolytic. Causes scarlet fever (rash-erythrogenic toxin), rheumatic fever (“Aschoff’s nodules”, myocarditis and chorea). M protein is anti-phagocytic. | Streptococcus pyogenes (Group A Strep, or GAS) Can also cause otitis media or misdirec Ab to cause AGN or RHD. Treatment: Penicillin |
Gram(+), pleomorph. Laryngitis (airway obstruction), pharyngitis, myocarditis, polyneuritis. Exotoxin (necessary for disease) carried on phage; turned on by low iron. Toxins kill superficial layers of cells and form a pseudomembrane. | Corynebacterium diphtheria Vaccination (DPT) against the toxin has drastically cut infection rates (seen mostly in poor countries). Treatment: Antitoxin+penicillin. Prophylaxis to close contacts. |
Gram(+) coccus, coagulase and catalase positive. Grows in grape-like clusters. Otitis externa, pneumonia, skin infections, septicemia. Capsules, Protein A. Pneumonia seen in CF patients and secondary post-viral infections. | Staphylococcus aureus Treatment: Very resistant to penicillin, sometimes to methicillin (MRSA), rarely to vancomycin, polymyxin ear drops. Give Flucloxacillin |
Gram(+), grows in chains. Dental caries, plaque; Glucan synthesis allows for tight adherence to teeth. | Streptococcus mutans (viridans group) Treatment: Removal of plaque (growth substrate) from teeth |
Gram(-) rod. Fastidious growth on chocolate agar. Acute epiglotitis, otitis media, pharyngitis, chronic bronchitis. Capsulated (typeable) cause bacteremia, meningitis. IgA protease, competence (DNA transformation). Seen in COPD, sickle cell, CF patients. | Haeamophilus influenza Treatment: Ampicillin, cefotaxime, chloramphenicol. HiB: polyribotol phosphate conjugated vaccine. |
Gram(+), diplococcus. Alpha-hemolytic, optochin-sensitive. Acute otitis media, chronic bronchitis, “typical” pneumonia. Most common bacterial meningitis. Can spread systemically to produce osteomyelitis, endocarditis, cellulitis. | Streptococcus pneumoniae Treatment: Ampicillin, or erythromycin if beta-lactam allergy. Pneumovax vaccine recommended for elderly. |
Fungus. Grows on SDA (Sabourand Dextrose Agar). Otitis externa. Oral thrush (immunocompromised or after broad spectrum antibiotics). Often normal flora | Candida albicans Treatment: topical antifungals (nystatin, clotrimazole) or oral antifungals (fluconazole), polymyxin ear drops |
Involves a distinct section of the lung. Fills alveoli with exudates, but limited by anatomy of lung. Commonly caused by pneumococcus (S. pneumoniae). | Lobar pneumonia Tx: Ampicillin |
Diffuse and patchy pneumonia, often caused by Mycoplasma species. | Bronchopneumonia (Chronic Bronchitis) Tx: Cefuroxime |
Invasion of the lung interstitium commonly caused by viral organisms (e.g., CMV pneumonitis in bone marrow patients, produces “owl’s eye” inclusion). Secondary bacterial infection. | Interstitial pneumonia Tx: Ampicillin + flucloxacillin |
“necrotizing pneumonia”, most common predisposing cause is aspiration of respiratory or gastric secretions. Endogenous anaerobes (Bacteroides & Fuscobacterium) cause foul smelling sputum. | Lung abscess Tx: Metronidazole 2-4 months |
M. pneumoniae, C. psittaci, C. pneumoniae, Legionella pneumophila, Coxiella burnetii | Primary Atypical Pneumonia |
What is most common cause of community acquired pneumonia? | Strep. pneumoniae Tx: Ampicillin + Erythromycin |
Cystic fibrosis leads to increased susceptibility to what organisms? | P. aeruginosa, H. influenza, and S. aureus pneumonias. |
(-)ss segmented RNA virus. Enveloped, Orthomyxovirus. Chronic Bronchitis, lower respiratory infections. Hemagglutinin (binding), neuraminidase (cleaving). Only RNA virus to replicate in nucleus. Transmitted by droplet inhalation. | Influenza Virus A, B, C Treatment: Vaccination (esp. high risk > 65yo or COPD), Zanamivir/Oseltamivir (neuraminidase inhibitors) |
(-)ssRNA virus. Paramyxovirus. Bronchiolitis (children get interstitial pneumonia). F (fusion) protein fuses host epithelium to form ‘syncytia’, G protein for attachment. Affects young infants with cough, tachypnea, cyanosis (peak mortality = 3 mo) | Respiratory Syncytial Virus (RSV) Treatment: Ribavirin, supportive (hydration, bronchodilators, oxygen) |
Massive pulmonary edema, hemorrhagic fever; 38% mortality, spread by aerosolized contaminated rodent urine or feces. | Hantavirus Cardiopulmonary Syndrome (HCPS) |
(-)ssRNA Paramyxovirus. Surface spikes (hemagglutinin + neuraminidase, fusion proteins). Viruses 1-3 cause pharyngitis, croup, otitis media, bronchiolitis and pneumonia. Virus 4 causes “common cold” illness. | Parainfluenza Virus Treatment: Ribavirin, supportive |
(-)ssRNA. Paramyxovirus. ‘Giant cell’ pneumonia (in immunodeficient) Highly contagious aerosolized particles. Replicates in epithelium of nasopharynx, middle ear, lung. Hallmarked by “cold symptoms”, conjunctivitis, and Koplik spots followed by rash. | Measles (aka Rubeola) Treatment: Vaccination (MMR), Ribavirin in extreme cases, ABx for secondary prophylaxis. Vitamin A (retinol) |
Gram(-) pneumonia (hospital acquired); aspiration pneumonia; cystic fibrosis. Often antibiotic resistant. Very common in cystic fibrosis patients, or following intubation. | Pseudomonas aeruginosa |
Does not gram stain serologically confirmed. Obligate intracellular pathogen, rising frequency. Perinatal pneumonia if mother was infected. | Chlamydia pneumoniae Treatment: Erythromycin |
Ziehl-Neelsen (acid fast) stain of sputum (mycolic acid). Air-borne transmission, engulfed by alveolar macrophages, inhibits phagolysome fusion, causes caseous granulomas (Ghon complex) in immunocompetent, disseminated (miliary) in immunocompromised. | Mycobacterium tuberculosis: Reactivation in apex of lungs. Treatment: Isoniazid, rifampicin, ethambutol. PPD test for exposure. BCG vaccine outside of the United States. |
Gram(-), fastidious on agar. Presents with systemic complications (mental, renal, hepatic) and bulk exposure after colonization of air conditioning systems or any water source (e.g., hospital taps, fountains, etc.) causing atypical pneumonia. | Legionella pneumophila Treatment: Erythromycin |
Gram(-) rod, lactose-fermentor, Capsule, often antibiotic resistant. Also seen in intubated patients. Aspiration pneumonia, often seen in alcoholics. | Klebsiella pneumoniae Treatment: Gentamycin, chloramphenicol or ciprofloxacin |
Gram(-), diplococcus, Oxidase-positive. Pneumonia, otitis media, sinusitis. Commonly secondary infections with lung cancers | Moraxella catarrhalis Treatment: Resistant to beta-lactams. |
No cell wall, fastidious agar growth. Acute bronchitis, arthralgia, atypical (walking) pneumonia, bronchiolitis (rare). Produces hydrogen peroxide that damages the mucorespiratory elevator. 4 year epidemic cycles, dry cough. | Mycoplasma pneumoniae Treatment: Tetracycline, Erythromycin, symptomatic |
Gram(-), Q-fever | Coxiella burnetii Treatment: Erythromycin |
Gram(-) coccobacillus. Oxidase positive. Whooping cough (dry, non-productive, paroxysmal). Adenylate cyclase toxin (inhibits immune response), Tracheal cytotoxin (inhibits clearance), Hemagglutinin (binding). Confined to respiratory epithelium. | Bordetella pertussis Treatment: DPT vaccine. Supportive, erythromycin. |
Atypical fungus causes interstitial pneumonitis in the immunocompromised (AIDS). Spreads by droplet transmission. | Pneumocystis jirovecii Treatment: TMP-SMX (Trimethoprim/sulfamethoxazole) |
Causes fungal ball of entangled hyphae. Attacks immunocompromised patients (AIDS). | Aspergillus fumigatus: allergic bronchopulmonary aspergillosis (APBA) Treatment: Antifungal, improve neutrophil count. |