Bordetella Infections: Symptoms, Diagnosis, Treatment, and Prevention

Introduction Genus Bordetella

Bordetella is a genus of small, gram-negative coccobacilli that are obligate human and animal pathogens. These bacteria are aerobic, non-motile, and fastidious in their nutritional requirements. The genus is best known for Bordetella pertussis, the causative agent of whooping cough, a highly contagious respiratory infection. Other species include Bordetella parapertussis, which causes a milder form of pertussis, and Bordetella bronchiseptica, which primarily infects animals but can occasionally affect humans. Bordetella organisms colonize the respiratory tract, attaching to ciliated epithelial cells and producing toxins that interfere with host defenses. Their medical importance lies in their ability to cause acute and sometimes severe respiratory diseases, particularly in infants and unvaccinated populations. Non-spore forming, Catalase +ve and Fastidious organism (require blood supplemented medium).

Bordetella species of clinical significance include

 B. pertussis

 B. parapertussis

 B. bronchoseptica

1.   Bordetella pertussis

B. pertussis is a small, non-motile, capsulated Gram negative coccobacillus.  It may occur singly or in chains with toluidine blue stain, bipolar metachromatic granules can be demonstrated.  It is obligate aerobic, catalase positive, pathogenic, causes pertussis (whooping cough or 100 day cough). B.pertusis infects its host by colonizing lung epithelial cells. Its virulence factors include pertussis toxin, adenylate cyclase toxin, filamentous haemagglutinin, pertactin, fimbria, and tracheal cytotoxin.

Pathogenicity and Clinical manifestation

B. pertussis causes whooping cough. There is a marked leukocytosis with an absolute lymphocytosis. Complications of infection include lung damage with emphysema, secondary infection leading to bronchopneumonia, convulsions and occasionally brain damage.  B. parapertussis causes a milder form of whooping cough. After an incubation period of about 2 weeks, the “catarrhal stage" develops, with mild coughing, low-grade fevers, coryza, congestion and sneezing conjunctival suffusion and eye tearing.  "paroxysmal" stage, the cough develops its explosive character and the characteristic "whoop" upon inhalation This leads to rapid exhaustion and may be associated with vomiting, cyanosis, and convulsions. The white blood count is high (16,000–30,000/ L), with an absolute lymphocytosis.  Convalescent stage (3-4 weeks ) Frequency and severity of the coughing gradually decrease. But secondary complications can occur.

What is whooping cough?

Whooping cough is caused by a bacteria named Bordetella pertussis. Acute, highly contagious, vaccine preventable disease. Whooping cough, also known as pertussis, is a highly contagious respiratory infection caused by the bacterium Bordetella pertussis. It is characterized by severe, rapid, and uncontrolled fits of coughing. The name "whooping cough" comes from the high-pitched "whoop" sound that some people make when they gasp for air after a coughing fit.

Haw to diagnosis B.Pertussis

Specimens: Preferably nasopharyngeal secretions collected by aspiration or a correctly taken pernasal swab. A saline nasal wash is the preferred specimen. Cough droplets expelled onto a "cough plate" held in front of the patient's mouth are sometimes used but are not as good as the saline nasal wash. Culture: For the isolation of B. pertussis must be cultured as soon as possible after they are collected.  A selective and enrichment medium such as charcoal cephalexin blood agar is recommended for the primary isolation of B. pertussis.  Small, convex, smooth colonies. Organisms are identified by immunofluorescence staining or by slide agglutination with specific antiserum. Charcoal cephalexin blood agar:  Widely used for primary isolation. When incubated for 2–6 days at 35–37 ºC in a moist aerobic atmosphere B. pertussis produces small pearly grey, shiny (mercury-like), usually mucoid colonies. Bordet-Gengou media (Potato-blood-glycerol agar) is selective media containing a high percentage of blood (20 30%), to inactivate inhibitors in the agar.

Haw to treatment B.pertussis

Sensitive to Erythromycin, tetracycline and chloramphenicol.

Prevention

Adequate active immunization of all infants. The best way to prevent Bordetella pertussis (whooping cough) is through vaccination.

Conclusion

Bordetella pertussis is a highly contagious bacterium that causes whooping cough, a serious respiratory infection especially dangerous in infants and young children. Despite the availability of effective vaccines, outbreaks still occur due to waning immunity and low vaccination coverage in some regions. Prevention mainly relies on widespread immunization, early detection, and timely treatment with antibiotics to reduce transmission. Strengthening vaccination programs and raising awareness remain the most effective strategies to control and ultimately reduce the global burden of pertussis.