Whooping Cough:You Won’t be Bored When I Tella

‘Bout This Kaitlin Allinger

Patient Information• Whoopi G., a 7 month old female, was brought to the hospital

because she had been experiencing numerous rapid coughing episodes that end with a long inspiratory effort that makes a “whoop” sound.

• These episodes sometimes cause her to turn blue and/or vomit.

• It was also noted that during the week prior to these episodes she had a runny nose, sneezing, occasional coughing, and a low-grade fever.

• Physical examination revealed that her pulse was 165 beats per minute and respiratory rate was 70 breaths per minute.

• A CBC was ordered and showed elevated lymphocytes.

• Gram-negative coccobacilli were recovered from a specimen collected from the posterior nasopharynx.

• The patient was diagnosed with whooping cough.

Explanation of Patient History and Results• A characteristic symptom is repetitive coughing spells that

cause a patient to gasp for breath

• Can lead to cyanosis and vomiting

• Lymphocytosis

• Caused by pertussis toxin

• Elevated pulse and respiratory rate

• Coughing spells cause difficulty breathing

• Insidious onset

• Initial symptoms similar to the common cold

Clinical Significance

• Bordetella pertussis • Causative agent of whooping cough

• Primarily affects infants and young children, especially if they are not vaccinated

• Adults and adolescents can become infected, but the disease is much milder and may be asymptomatic

http://www.cdc.gov/vaccines/pubs/pinkbook/pert.html#diagnosis

Clinical Significance

• Complications include:

• Secondary bacterial pneumonia- 5.2%

• The cause of most pertussis-related deaths

• Seizures- 0.8%

• Encephalopathy – 0.1%

• Death – 0.2%

• 83% of deaths occur in infants <3 months

Clinical Features• Incubation period: usually 7-10 days• 3 Stages:

http://www.cdc.gov/pertussis/images/Pertussis-timeline-lg.jpg

Epidemiology

• Worldwide

• Infection only occurs in humans

• Adults are often the source of infection for children

• Highly contagious, especially during the first 1-2 weeks

• Transmitted by respiratory droplets

http://pathmicro.med.sc.edu/ghaffar/bord-hemo.htm

Culture Characteristics

• Aerobic Gram-negative coccobacilli

• Fastidious

• Regan Lowe Media (Charcoal Blood Agar)

• Selective for Bordetella sp.

• Incubate at 35C, moist chamber, ambient air

• Growth at 2 days

• Appearance on Regan-Lowe:

• -Small, domed, glistening,

white/gray colonies

https://catalog.hardydiagnostics.com/cp_prod/content/hugo/Regan-LoweCharcBldAgar.htm

Identification• Laboratory diagnosis of Bordetella pertussis by culture:

• 2 specimens, one through each nostril, collected from the posterior nasopharynx with a Dacron or calcium alginate swab

• Transport in Amies or Regan-Lowe transport medium

• Inoculate on Regan-Lowe agar (35C, ambient air, moist chamber)

• Hold for 7 days

• Identify suspicious colonies with a Gram-stain and fluorescein-labeled antisera or agglutinating antisera

• No routine susceptibility testing is performed

http://www.stanfordlab.com/esoteric/Virology.html

Virulence Mechanisms

• Pertussis toxin

• Contributes to bacterial binding of cilia, causes lymphocytosis, and impairs chemotaxis

• Adenylate cyclase toxin

• Inhibits phagocyte and NK cell functions

• Tracheal cytotoxin

• Inhibits DNA synthesis and promotes cell death

• Filamentous hemagglutinin and pertactin

• Attachment to epithelial cells

Fig. 1: Synergy between pertussis toxin and filamentous hemagglutinin in binding to

ciliated respiratory epithelial cells.

Tozzi A E et al. CMAJ 2005;172:509-515

©2005 by Canadian Medical Association

Treatment and Prevention

• Mostly supportive therapy

• Erythromycin is the drug of choice – used to decrease the number of organism in secretions to prevent the spread of infection

• Vaccine

• DTap (pediatric) or Tdap (adolescent and adults)

• Contains:

• Inactivated diphtheria and tetanus toxins

• Acellular pertussis subunit

http://ghstravelsafe.com/vaccinations/

Treatment and Prevention

• Pediatric vaccination schedule:

• 4 doses of DTap are given

• The first 3 doses given at 4- to 8-week intervals starting at 6 weeks to 2 months of age

• The fourth dose should be given at 15–18 months of age

• Adolescents and Adults

• Tdap is given as a booster (a weaker formulation)

• Given at 11-18 years of age (11 or 12 is recommended)

• Can also be given to adults 19-64 years old

http://www.cdc.gov/vaccines/pubs/pinkbook/downloads/pert.pdf

Sources

• http://www.cdc.gov/vaccines/pubs/pinkbook/pert.html#diagnosis

• http://pathmicro.med.sc.edu/ghaffar/bord-hemo.htm

• http://www.cmaj.ca/content/172/4/509.full.pdf+html

• Mahon, Connie R., Donald C. Lehman, and George Manuselis. Textbook of Diagnostic Microbiology. Maryland Heights, MO: Saunders/Elsevier, 2011. 423-426. Print.