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Simple and efficient method for clinical isolation of Bordetella pertussis
1Department of Pediatrics, School of Medicine, Keio University, Tokyo, Japan.
Abstract:
Commercially available Amies transport medium with charcoal and three isolation media were tested to assess their efficiency in the clinical isolation of B. pertussis. First, the isolation rates of B. pertussis were compared between direct inoculation of nasopharyngeal specimens and inoculation after being stored in Amies transport medium for eight hours or less. The organism was detected in 43 specimens from 29 patients with at least one of the two inoculation methods. The comparative isolation rates were 81% (35 of 43) for both direct inoculation and transport medium. Second, nasopharyngeal specimens were incubated for five days at 35 degrees C on the three media; Bordet Gengou Medium (BG) with 5 micrograms of CEX per ml, Cyclodextrin Solid Medium (CSM) with 5 micrograms of CEX per ml, and Charcoal Agar with 40 micrograms of CEX per ml. The organism was detected from 44 nasopharyngeal specimens of 20 patients on at least one of the three tested media. The comparative isolation rates were 91% (40 of 44) on BG with 5 micrograms of CEX per ml, 93% (41 of 44) on CSM with 5 micrograms of CEX per ml, and 91% (40 of 44) on CA with 40 micrograms of CEX per ml. Although no differences in the isolation rates were observed among the three media, the appearance of the colonies was earlier by one day on BG than the other two media. The detection of B. pertussis was occasionally easier on CA than on the other two because of its higher suppression of nasopharyngeal flora.(ABSTRACT TRUNCATED AT 250 WORDS)
Insights
This study found that Amies transport medium and direct inoculation showed similar B. pertussis isolation rates. Bordet Gengou, Cyclodextrin Solid Medium, and Charcoal Agar media also demonstrated comparable B. pertussis isolation efficiencies.
Area of Science:
- Microbiology
- Clinical Diagnostics
- Infectious Diseases
Background:
- Bordetella pertussis (B. pertussis) causes whooping cough, a significant public health concern.
- Accurate and efficient laboratory isolation of B. pertussis is crucial for timely diagnosis and treatment.
- Optimizing transport and culture media can improve clinical detection rates.
Purpose of the Study:
- To evaluate the efficiency of Amies transport medium for B. pertussis isolation.
- To compare the performance of three different isolation media for B. pertussis.
- To assess the impact of specimen transport time on B. pertussis detection.
Main Methods:
- Nasopharyngeal specimens were tested using direct inoculation and after storage in Amies transport medium.
- Isolation rates were compared between direct inoculation and transport medium methods.
- Three selective media (Bordet Gengou, Cyclodextrin Solid Medium, Charcoal Agar) with CEX antibiotic were evaluated for B. pertussis culture.
Main Results:
- Amies transport medium and direct inoculation yielded similar B. pertussis isolation rates (81%).
- Bordet Gengou Medium (91%), Cyclodextrin Solid Medium (93%), and Charcoal Agar (91%) showed comparable isolation efficiencies.
- Colony appearance was one day earlier on Bordet Gengou Medium; Charcoal Agar offered better suppression of contaminating flora.
Conclusions:
- Amies transport medium is effective for short-term (≤8 hours) preservation of B. pertussis.
- Bordet Gengou Medium, Cyclodextrin Solid Medium, and Charcoal Agar are all suitable for B. pertussis isolation.
- Charcoal Agar may be advantageous due to superior inhibition of normal nasopharyngeal flora, potentially simplifying detection.