Case Study 9
Pathogenic Bacteriology
2009
Omar Ahmed
Hank Hsieh
Rochelle Songco
Case Summary
• 5 ½-week-old male
• 10 day history of choking spells
• Repetitive coughing, turning red, gasping for
breath
• Vomiting associated with choking spells in prior
2 days
• Pulse – 160 bpm (elevated)
• Respiratory rate – 72/min (elevated)
• Chest radiograph is clear and trachea is normal
• White cell count – 15,500/µL with 70% lymphocytes
Key Information Pointing to
Diagnosis
• An elevated white cell count with 70%
lymphocytes
• Coughing spells, turning red, gasping for breath
• Episodes of vomiting
• Chest radiograph is clear indicating no
pneumonia infection
• No tracheal abnormalities
 These are all consistent with a pertussis
infection
The Diagnosis for Case 9
• Bordetella pertussis
• Nasopharyngeal swab shown below
source: faculty.matcmadison.edu/mljensen
Classification,Gram Stain Results, and
Microscopic Appearance of
Bordetella pertussis
• Genus: Bordetella
• Gram-negative
• Coccobacillus
• Aerobic
source: historique.net/microbes
Diseases and Pathogenesis of
Bordetella pertussis
• Pertussis, which causes whooping cough
• Infection of the respiratory tract
• Children and young infants are most at
risk
• Most contagious before coughing begins
Diagnosis/Isolation/Identification/ of
Bordetella pertussis
• Diagnosis based on…
– repetitive coughing with choking, vomiting, and gasping for
breath
– Elevated pulse and respiratory rate
– Elevated lymphocyte levels
• Caused by a blocking of homing of lymphocytes to the spleen
and lymph nodes
– Culture from nasopharyngeal swab is most common method of
detection due to the bacterial presence in nose and throat
• Bordet-Gengou medium
• Charcoal-horseblood agar
• Detection of Bordetella DNA by PCR
• Detection of IgA antibodies with ELISA
Therapy, Prevention and Prognosis
of Patient Infected with
Bordetella pertussis
• Erythromycin is the drug of choice against
pertussis infection
– Reduces duration by 5-10 days but not the
course of the infection
– Bacteria is slow growing so cough persists
• DTaP vaccine available for children
– Reported cases down 97% from pre-vaccine era
• Tdap booster vaccine for adolescents and
adults
a
A marked decrease in L-selectin expression by leucocytes in
infants withBordetella pertussisinfection: leucocytosis explained?
• Hodge, Greg, et al, 2003, A marked decrease in L-selectin
expression by leucocytes in infants withBordetella pertussisinfection:
leucocytosis explained?, Respirology, 8: 157-162.
• Blood collected from 11 infants with B. pertussis infection prior to
antibiotic therapy. Control group of 11 infants with non-pertussis
related hospital admission.
• Full blood counts conducted for WBCs and also test of cell origin
(lymphoid, granulocytic, or monocytic).
• Patients with B. pertussis infection showed a much higher absolute
number of neutrophils, monocytes, and lymphocytes compared to
control
– L-selectin is removed from leucocytes by pathogen
• Prevents migration of leucocytes and homing and invasion of T and B cells
to peripheral lymphoid tissues
• Leukocytosis is consistent with an infection of Bordetella pertussis
= Take Home Message =
Bordetella pertussis
• Pertussis is a respiratory infection which causes “whooping cough”
• Typical symptoms are initially cold-like followed by a stage of rapid
coughing and finally a recovery stage of coughing which can last for
weeks or months.
• Pathogen which causes this infection is Bordetella pertussis
• Diagnostics include a nasopharyngeal swab culture, DNA PCR, and
ELISA test for antibodies
• Erythromycin is the primary antibiotic used against an pertussis
infection
• Most children recover from the illness but pneumonia, apnea,
encephalopathy, and rib fractures are complications associated
with a pertussis infection
• Immunization is effective against pertussis infections
• Disease is spread by coughing and sneezing
• Non-vaccinated infants and adolescents at most risk
References
• "Bordetella". National Center for Biotechnology
Information. March, 09, 2009
<http://www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=mme
d.chapter.1684>.
• "Vaccines VPD-VAC-Pertussis-main page". Centers for
Disease Control and Prevention. March, 08, 2009
• "Pertussis Bacterial Infections Merck Manual Home
Edition". MERCK. March, 07, 2009
<http://www.merck.com/mmhe/sec23/ch272/ch272g.html
>.
• McQueen, Nancy. Winter 2009. Bordetella, Francisella,
and Brucella