Case Study 9

Pathogenic Bacteriology2009

Omar AhmedHank 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 abnormalitiesThese 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 a 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 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=mmed.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