Respiratory bugs

Question 1

Most common cause of the common cold?

Answer 1

Rhinovirus

Other causes: coronaviruses, adenoviruses, influenza C virus, coxsackievirus

Question 2

Acute chest syndrome: fever with pleuritis

Answer 2

Coxsackievirus

Question 3

Most common cause of croup (laryngotracheobronchitis) in infants?

Answer 3

Parainfluenza
Inspiratory stridor (UA obstruction) due to submucosal edema in trachea; brassy cough; signs of respiratory distress
Anterior x-ray of neck shows “steeple sign,”- mucosal edema in the trachea (site of obstruction)
Bronchiolitis in infants
Treatment: cold water humidifiers and aerosolized racemic epinephrine

Question 4

Common pneumonia in immunocompromised hosts (e.g., bone marrow transplants, AIDS)?

Answer 4

CMV
Enlarged alveolar macrophages/pneumocytes, contain eosinophilic intranuclear inclusions surrounded by a halo
Treatment: cidofovir, foscarnet, ganciclovir

Question 5

Causes worldwide epidemics; pneumonia may be complicated by a superimposed bacterial pneumonia (usually Staphylococcus aureus)?

Answer 5

Influenza
Clinical: fever, headache, cough, myalgias, chest pain
Vaccination: mandatory for people >65 years old, people with chronic illnesses
Treatment: neuraminidase inhibitors (e.g., oseltamivir)
Associations: Reye syndrome with salicylate ingestion; Guillain-Barré syndrome

Question 6

Fever, cough, conjunctivitis, and excessive nasal mucus production. Koplik spots in the mouth precede onset of the rash?

Answer 6

Rubeola

Warthin-Finkeldey multinucleated giant cells are a characteristic-finding

Question 7

Most common cause of pneumonia and bronchiolitis (wheezing) in infants

Answer 7

RSV
Causes otitis media in older children
Hand washing and use of gloves prevents nosocomial outbreaks in nurseries, winter
Passive immunization (high risk children): palivizumab (monoclonal antibody) reduces hospitalization rates between November and April

Question 8

First transmitted to humans through contact with masked palm civets (China) and then from human-to-human contact through respiratory secretions (e.g., hospitals, families)?

Answer 8

SARS
Develop severe respiratory infection
Diagnose with viral detection by PCR assay or detection of antibodies
Children: no therapy or vitamin A

Question 9

Transmission: inhalation of urine/feces from deer mice in Southwestern US?

Answer 9

Hantavirus
Pulmonary syndrome: ARDS, hemorrhage, renal failure
Diagnosis: detect viral RNA in lung tissue
No effective treatment
High mortality rate

Question 10

Newborn pneumonia, Afebrile, staccato cough (choppy cough), conjunctivitis, wheezing?

Answer 10

Chlamydia trachomatis

Tx: erythromycin

Question 11

Most common cause of atypical pneumonia?

Answer 11

Non productive pneumonia
community
Mycoplasma, M. pneumoniae
Common in adolescents and military recruits (closed spaces)
Risk factor for Guillain-Barré syndrome
Insidious onset with low-grade fever
Treatment: erythromycin; azithromycin; clarithromycin

Question 12

Most common cause of typical community-acquired pneumonia?

Answer 12

Streptococcus pneumoniae
Gram-positive lancet-shaped diplococcus
Rapid onset, productive cough, signs of consolidation
Urine antigen test excellent screen
Treatment: penicillin G (penicillin sensitive); vancomycin +/− rifampin (penicillin resistant)

Question 13

Yellow sputum – superimposed on influenza pneumonia and measles pneumonia?

Answer 13

Staphylococcus aureus
Major lung pathogen in cystic fibrosis and IV drug abusers
Hemorrhagic pulmonary edema, abscess formation, and pneumatoceles (thin-walled air-filled cysts that develop in the lung parenchyma, usually after pneumonia)
Treatment of pneumonia: methicillin-sensitive: nafcillin or oxacillin; methicillin resistant: vancomycin

Question 14

Shaggy gray membranes in the oropharynx and trachea; toxic myocarditis (death)

Answer 14

Corynebacterium diphtheriae
Gram-positive rod
Toxin inhibits protein synthesis by ADP-ribosylation of elongation factor 2 involved in protein synthesis
Toxin also impairs β-oxidation of fatty acids in the heart
Treatment: erythromycin

Question 15

Bacillus anthracis - describe features?

Answer 15

gram positive rod, soil
Exotoxins: edema factor (activates adenylate cyclase); lethal factor (inhibits a signal transduction protein involved in cell division); protective antigen (assists entry of above toxins into cells)
Treatment: ciprofloxacin

Question 16

Produces whooping cough, transmitted by droplet infection?

Answer 16

Bordetella pertussis
Gram-negative rod
Diagnosis: nasopharyngeal swabs using special cough plate; direct immunofluorescence of swab material
Treatment: erythromycin

Question 17

Common cause of sinusitis, otitis media, conjunctivitis (pink-eye)?

Answer 17

Haemophilus influenzae
Inspiratory stridor may be due to acute epiglottitis
Swelling of epiglottis produces “thumbprint sign” on lateral x-ray of the neck
Most common bacterial cause of acute exacerbation of COPD
Treatment: cefotaxime; ceftriaxone

Question 18

Water-loving bacteria most often transmitted by respirators?

Answer 18

Pseudomonas aeruginosa
Green sputum (pyocyanin)
Most common cause of nosocomial pneumonia and death due to pneumonia in cystic fibrosis
Pneumonia often associated with infarction due to vessel invasion
Treatment: antipseudomonal β-lactam + aminoglycoside + antipseudomonal quinolone or macrolide

Question 19

Common cause of pneumonia in alcoholics?

Answer 19

Klebsiella pneumoniae
Gram-negative fat rod surrounded by a mucoid capsule – causing lobar pneumonia and typical pneumonia in elderly patients in nursing homes
Common cause of pneumonia in alcoholics; however, S. pneumoniae is still the most common pneumonia
Typical pneumonia associated with blood-tinged, thick, mucoid sputum
Lobar consolidation and abscess formation are common
Treatment: varies with susceptibility

Question 20

Water-loving bacterium (water coolers; mists in produce section of grocery stores; outdoor restaurants in summer; rain forests in zoos)?

Answer 20

Legionella pneumophila
Gram-negative rod (requires IF stain or Dieterle silver stain to identify in tissue)
Antigens can also be detected in urine
Risk factors: alcoholic, smoker, immunosuppression
Atypical pneumonia associated with high fever, dry cough, flu-like symptoms
Assoc. destroy JG apparatus
–hyporeninemic hypoaldosteronism (type IV renal tubular acidosis—hyponatremia, hyperkalemia, metabolic acidosis)
–Urine antigen test excellent screen
–Treatment: fluoroquinolone; azithromycin

Question 21

Transmitted by bite of rat flea; primary reservoir for bacteria are ground squirrels in the Southwest?

Answer 21

Yersinia pestis
Gram-negative rod
Cause of plague
Three types of disease: bubonic (most common), pneumonic (transmitted by aerosol), septicemic
Treatment: pneumonic type: gentamicin

Question 22

Budding yeast with narrow-based buds; surrounded by a thick capsule, pigeons?

Answer 22

Cryptococcus neoformans
Primary lung disease (40%): granulomatous inflammation with caseation. Do not have to be immunocompromised.
Treatment: fluconazole

Question 23

Fruiting body and narrow-angled (

Answer 23

Aspergillus fumigatus
Aspergilloma: fungus ball (visible on x-ray) that develops in a preexisting cavity in the lung, cause of massive hemoptysis
Repeated attacks may lead to bronchiectasis and interstitial lung disease; treatment with corticosteroids
Treatment: voriconazole

Question 24

Wide-angled hyphae (>45 degrees) without septa - diabetics and immunocompromised?

Answer 24

Mucor
Vessel invader and produces hemorrhagic infarcts in the lung
Invades the frontal lobes in patients with diabetic ketoacidosis (rhinocerebral mucormycosis)
Treatment: liposomal amphotericin B

Question 25

Contracted by inhaling arthrospores in dust while living or passing through arid desert areas in the Southwest (valley fever)?

Answer 25

Coccidioides immitis
Spherules with endospores in tissues increased after earthquakes (increased dust)
Flu-like symptoms and erythema nodosum
Granulomatous inflammation with caseous necrosis
Treatment: usually self-limited; if severe: itraconazole or fluconazole

Question 26

Yeast forms are present in macrophages, coin lesions, Midwest, Ohio area?

Answer 26

Yeast forms are present in macrophages
Most common systemic fungal infection
Endemic in Ohio and central Mississippi river valleys
Inhalation of microconidia in dust contaminated with excreta from bats, starlings, or chickens
Simulates TB lung disease; produces coin lesions, consolidations, miliary spread, and cavitation
Marked dystrophic calcification of granulomas; most common cause of multiple calcifications in the spleen
Treatment: usually self-limited; if severe, itraconazole or liposomal amphotericin B

Question 27

Yeasts have broad-based buds and nuclei, SE regions?

Answer 27

Blastomyces dermatitidis
Yeasts have broad-based buds and nuclei
Occurs in Great Lakes region, central, and southeastern US
Most often associated with fishing, hunting, gardening, exposure to beaver dams (beavers are reservoirs for the fungus)
Male dominant disease
Produces skin and lung disease; skin lesions simulate squamous cell carcinoma
Granulomatous inflammation with caseous necrosis
Treatment: liposomal amphotericin B

Question 28

Primarily an opportunistic infection; occurs when CD4 count

Answer 28

Pneumocystis jiroveci
Cysts and trophozoites present; cysts attach to type I pneumocytes
Common initial AIDS-defining infection
Predominantly produces pulmonary disease. Patients develop fever, dyspnea, and severe hypoxemia. Diffuse intra-alveolar foamy exudates with cup-shaped cysts best visualized with silver or Giemsa stains. Chest x-ray shows diffuse alveolar and interstitial infiltrates.
Treatment: TMP-SMX given prophylactically when CD4 count

Question 29

Drugs used to treat P. aeruginosa?

Answer 29

• cefoperazone, ceftazidime, and cefepime.
• Cephalosporins, β-lactam antibiotics, inhibit bacterial cell wall synthesis. Cause anaphylaxis and nephrotoxicity if + aminoglycosides.
• Cefoperazone and ceftazidime, 3rd gen
• Cefepime 4th gen against gram-+ and gram-neg