Upper Respiratory Bugs Flashcards
Common Cold
Most common URI.
Rhinoviruses cause the majority of colds (50%) particularly in adults.
Preferentially replicate at 33 degrees (like upper airways, but can’t invade lungs or body)
Parainfluenza, coronaviruses, influenza C virus, coxsackieviruses A + B, and Adenoviruses are also important causes.
More common in winter months (adeno in summer)
Sx: nasal discharge and congestion, mild sore throat, cough, rhinorrhea and LACK of fever. Usually last a week or less. Children may have a mild fever.
No therapy indicated.
Sinusitis
Typical complication of a viral URI caused by secondary bacterial infx. Often follows a cold, dental procedure, or allergic rhinitis.
2% of adult and 10% of children’s viral rhinosinusitis progress to acute bacterial infections.
Sx: fever, pus-filled nasal discharge, and sinus tenderness. (mucus color and consistency will not definitely indicate a bacterial rather than viral infx.) Bacterial sinusitis is likely if sx persist for more than 7 days or if there is facial swelling or pain or fever > 102
Common bugs: Strep pneumo, H. influenzae.
Rx: Oral hydration and nasal saline washes and steam. Acetaminophen and decongestants. Mucolytics.
Amoxicillin or azithromycin if bacterial.
Fungal sinusitis is rare and usually identified after antibacterial drugs fail to clear the sinus infection.
Aspergillus fumigatus is the most likely cause –> treat w/ mechanical removal of the organism. (immunocompromised can have more sever infx leading to eye and brain involvement)
Pharyngitis
In young children ( run rapid strep test (sensitive)
Treat strep pharyngitis w/ penicillin or erythromycin for those allergic
Viral rx - acetaminophen and saline gargles.
Laryngitis / Croup
Sx:
- Fever of 100-102
- restlessness, SOB.
- bark-like cough; respiratory stridor (noisy breathing) at night
- Usually begins w/ mild URI and general cold sx, nasal congestion, sore throat, and cough that lasts 2-3 days.
Children w/ severe croup have primarily inspiratory stridor at rest w/ nasal flaring and suprasternal and intercostal retractions. Lethargy or agitation may be a result of hypoxemia.
Warning signs: tachypnea, tachycardia, lethargy, pallor, and hypotonia. Cyanosis is a late and ominious sign.
Complications related to airway maintenance (atelectasis, ptx, etc.)
Usually peak over 3-5 days and resolve within 4-7 days. Most often found
Person to person contact is the usual means of spread of all types of croup.
Typically self limiting.
Ddx vs croup: Gradual onset, absent drooling, barking cough, and positive steeple sign.
Respiratory System Defenses
- ) Mucociliary lining of the nasal cavity
- ) Change of direction of the airway from the sinuses to the pharynx (location of the adenoids)
- ) The ciliary elevator
- ) Normal flora competition (staphylococci)
- ) Alveolar macrophages eliminate microorganisms in the lungs.
Pathogen Initiation of Disease
- ) There must be a sufficient amt. of microorganisms inhaled in order to establish infection
- ) The infectious particles must be airborne
- ) The airborne particles must be viable in the air
- ) The organism must be deposited in the tissue susceptible to infection of the host.
Epiglottitis
Rare and life threatening
Caused by Beta-hemolytic strep - group A (most common), B, C or H. influenza type b
Rx: Secure airway; broad-spectrum second or third generation cephalosporins in combination w/ naf/dic
Ddx vs croup = sudden onset, high fever, drooling, no cough, positive thumb sign
Rhinovirus
Class IV
- RNA virus
- Icosahedral Nucleocapsid
- Nonenveloped
- SS + nonsegmented
- Picornavirus
Clinical presentation - common cold
Spreads by contact or aerosol formation.
Rx: supportive care, no vaccine
Paramyxovirus (parainfluenza virus)
Class V
- RNA virus
- Helical Nucleocapsid
- Enveloped
- SS - nonsegmented
- paramyxoviriduae
Clinical presentation - children = croup and pneumonia. Adults common cold (moderately severe)
Virulence factors: Viral fusion (F) surface proteins (causes multinucleate giant cells) .
Pathology: Inhaled through aerosols.
Dx: Symptoms. Anit-HA antibodies.
Treatment - supportive care, corticosteroids.
Coronavirus
Class IV
- Helical Nucleocapsid
- Enveloped
- SS + nonsegmented
- Coronaviridae
Second most common cause of common cold.
Pathology - inhaled through aeresol. 3 day incubation period. 6-7 days in length.
Treatment - supportive
Adenovirus
Group I
- DNA Virus
- Icosahedral Nucleocapsid
- Nonenveloped
- DS linear DNA (Group I)
- Adenoviridae
- Mastadenovirus
Clinical presentation - common cold, conjunctivitis, hemorrhagic cystitis, and gastroenteritis.
Dx: isolate virus in cell culture, serology
Rx: Vaccine of live viruses of specific serotypes (only used in the military)
Strep pneumoniae
- Gram +
- diplococci
- catalase -
- alpha hemolytic
- Bile-Esculin Negative
- Optochin Susceptible
- Quellung reaction
Clinical presentation - local = lobar pneumonia, otitis media. Systemic = meningitis.
Rx: Penicillin or cephalosporins, except vancomycin for meningitis. Pneumovax and Prevnar.
Haemophilus Influenzae
- Gram -
- Coccoballil, pleomorphic
- X and V factors required
- grows on chocolate agar
- Immunofluorescence and + Quelling test
Clinical presentation: local - epiglottitis, otitis media, pneumonia; systemic - meningitis, septic arthritis, cellulitis.
Virulence factors - IgA protease, capsule.
Rx - Third generation cephalosporin (ceftriaxone). Hib vaccine, rifampin ppx for close contacts.
Strep Pyogenes
- Gram +
- Cocci
- Catalase -
- Beta Hemolytic
- Bacitracin Sensitive
Virulence factors: Streptokinase, M protein, hyaluronidase, DNAse
Clinical presentation - pharyngitis, impetigo, erysipelas, and cellulitis.
Rx: Penicillin G
Corynebacterium Diptheriae
- Gram +
- Bacilli
- Non-spore forming
- Non-motile
- Looks like chinese letter under microscope
- black colonies on potassium tellurite
Clinical presentation - formation of pseudomembrane, airway obstruction, systemic - myocarditis and polyneuritis.
Treatment - antitoxin, penicillin or erythromycin. DTaP vaccine w/ boosters.
Virulence factors - diptheria toxin (cardiac issues and cranial and peripheral nerve palsy.
