Microsoft word - bordetella pertussis mh final _2_.doc

UPDATE:
Bordetella pertussis

Whooping cough is a highly contagious respiratory disease caused by the gram negative coccobacillus Bordetella
pertussis. In 2010, 27,550 cases were reported in the U.S. Outbreaks are most common in fall and winter, but may
occur any time of the year.
AFTER EXPOSURE TO ORGANISM:


Incubation Period: 4 to 21 days
Classic Symptoms:
Catarrhal Stage:
runny nose, sneezing, mild cough, low grade fever:
Paroxysmal Stage:
Staccato cough, whoop, post-tussive vomiting: 1 to 10 weeks
Convalescent Stage:
2 to 4 weeks or more (may last for months)
Atypical Presentation:
Patients may also be asymptomatic or have a prolonged nondescript cough and infants may present with
choking and apnea. Differential diagnosis of atypical symptoms includes Adenovirus, Parainfluenza and
Respiratory syncytial virus, Chlamydia pneumoniae and Mycoplasma pneumoniae.
Testing for B. pertussis is an important public health issue. Identification of people infected with the organism
allows the Public Health Department to identify and prophylax contacts of the patient, some of whom may be in high
risk groups.
• Populations most at risk for serious infections are infants and older adults, with complications which include
seizures, pneumonia, encephalopathy, or death. • B. pertussis is a strictly human pathogen with a high attack rate infecting 80-90% of susceptible contacts. It is spread by respiratory droplets and requires close contact (less than 3 feet) or direct contact, such as touching, to transmit disease. Masks and frequent hand washing by both caregivers and patients help prevent transmission of the disease. • Pertussis occurs in persons at any age regardless of immunization status. Immunization protects young children from the serious side effects of disease, but does not prevent infection. Immunity to pertussis wanes after 5 to 12 years. • Hospitalized patients with suspected or documented B. pertussis infection should be placed in Droplet Precautions until considered noninfectious (e.g., after 5 days of appropriate antibiotic therapy). Patients presenting to outpatient areas, e.g., clinical offices or the hospital for testing, should wear a mask.
LABORATORY TESTING:

• Asymptomatic patients should not be tested because the likelihood of obtaining a false-positive result is
increased.
• PCR is the recommended testing method for patients who have symptoms consistent with B. pertussis • Serology is NOT recommended for diagnosis because:
o Serologic tests are not standardized between laboratories. o Most serologic tests are not approved for diagnostic use. o They are difficult to interpret because antibody response differs due to age, and previous exposure to o They require comparison of an acute and convalescent specimen for maximum specificity. o Asymptomatic people can have rises in titer after exposure. • The sensitivity and specificity of all laboratory testing for B. pertussis depends on a variety of factors • For best results; collect the specimen properly, early in disease, before antibiotics, and transport promptly.
Previously, the laboratory requested that all samples be tested by PCR and culture in parallel in order to provide
material for epidemiologic studies. However, given that the vast majority of persons tested are negative, this practice
was extremely low yield. The CDC only recommends submitting cultures in one or more suspected cases when there
is suspicion of an outbreak. Therefore, the laboratory has discontinued the practice of performing culture in parallel
as a routine. We recommend culture only in select cases after a patient has had a positive PCR, and where
material is needed for epidemiologic studies or to confirm the specificity of the assay in an outbreak situation.
Culture is more likely to be positive if collected early in the disease, and prior to antibiotic administration.
SPECIMEN COLLECTION:
• The best specimen is a posterior nasopharyngeal specimen obtained using a Dacron minitip swab slowly inserted
into a nostril and pushed back until posterior nasopharynx is reached. Leave swab in place for 15-30 seconds and rotate in place to collect cells. Repeat procedure with other nostril. Alternately, an aspirate may be obtained. These procedures can be done at the hospital by a respiratory therapist. The pertussis kit with instructions can be obtained from the laboratory.
TREATMENT:
• Antibiotic therapy is administered for the purpose of preventing the spread of the organism to other persons or as
prophylaxis to prevent disease. It may or may not modify symptoms in patients with disease. Patients are considered non-infectious after a full 5 days of appropriate antibiotics. • Initiating laboratory testing, treatment, or prophylaxis after three weeks of onset of cough is of limited value in cases or their contacts and is not routinely recommended. Exceptions to this include:

-treatment up to 6 weeks after cough onset -prophylaxis given up to 6 weeks after exposure • The anti-microbial agents and dosages used for chemoprophylaxis of contacts are the same as that recommended
1. Azithromycin

• Infants aged <6 months: 10 mg/kg per day for 5 days. • Infants and children aged >6 months: 10 mg/kg (maximum: 500 mg) on day 1, followed by 5 mg/kg per day (maximum: 250 mg) on days 2—5. • Adults: 500 mg on day 1, followed by 250 mg per day on days 2—5.
2. Erythromycin

• Infants aged <1 month: not preferred because of risk for infantile hypertrophic pyloric stenosis (IHPS). Azithromycin is recommended antimicrobial agent. If azithromycin is unavailable and erythromycin is used, the dose is 40—50 mg/kg per day in 4 divided doses. These infants should be monitored for IHPS.* • Infants aged > 1 month and older children: 40—50 mg/kg per day (maximum: 2 g per day) in 4 • Adults: 2 g per day in 4 divided doses for 14 days. *Health-care providers who prescribe erythromycin rather than azithromycin to newborns should inform parents about the possible risks for IHPS and counsel them about signs of IHPS. 3. Clarithromycin

• Infants aged <1 month: not recommended. • Infants and children aged >1 month: 15 mg/kg per day (maximum: 1 g per day) in 2 divided doses • Adults: 1 g per day in two divided doses for 7 days.
4. Alternate
(TMP-SMZ). TMP-SMZ is used as an alternative to a macrolide antibiotic in
patients aged >2 months who have contraindication to or cannot tolerate macrolide agents, or who are infected with a macrolide-resistant strain of B. pertussis. Macrolide-resistant B. pertussis is rare. • Infants aged 2 months: contraindicated. • Infants aged > 2 months and children: trimethoprim 8 mg/kg per day, sulfamethoxazole 40 mg/kg • Adults: trimethoprim 320 mg per day, sulfamethoxazole 1,600 mg per day in 2 divided doses for 14 • Initiating laboratory testing, treatment or prophylaxis after three weeks of onset of cough is of limited value in cases or their contacts and is not routinely recommended (except in pregnancy and infancy).

LABORATORY INFORMATION:
• Please order PCR for B. pertussis.
• PCR should ideally be tested from NP specimens taken at 0-3 weeks following cough onset, but may provide accurate results for up to 4 weeks of cough in infants or unvaccinated persons. • Serology is not recommended for diagnosis of B. pertussis.
• Turnaround time after specimen is received:
*PCR:

REFERENCES:
1.
CDC 2011 “Best Practices for Health Care Professionals on the Use of Polymerase Chain Reaction (PCR) American Academy of Pediatrics 2009 Red Book
SCIENTIFIC INFORMATION CONTACT:

Dr. Tess Karre, Pathologist—Director of Microbiology Dr. Robert Penn—Infectious Disease Associates P.C. Drs. Chatterjee and Varman—Pediatric Infectious Disease Drs. Kotula and Gholami—Methodist Physicians Clinic Infectious Disease

Source: http://thepathologycenter.org/uploads/PDFs/briefs/Bordetella%20pertussis%20MH%20final.pdf