Chapter 16: INFECTIOUS DISEASES

NOTE/PEARL: Know the infectious diseases section well for the pediatric boards! Board questions with a great deal of cross-subject testing is common. The American Board of Pediatrics (ABP) expects you to be able to differentiate infections from metabolic disorders.

ANTIBIOTICS – A BRIEF REVIEW

ANTIBIOTIC AGE PEARLS

AGE LIMITATIONS: When choosing an antibiotic (especially tetracycline, fluoroquinolones, and macrolides), ALWAYS look at the age of the patient.

• TETRACYCLINE may be given after the age of 8. DOXYCYCLINE was previously contraindicated in children under 8, but studies have supported its use in children under 8 for short courses <21 days.

PEARL: If you diagnose a 5-year-old child with Rocky Mountain Spotted Fever, go ahead and GIVE doxy­cycline. That is the first-line therapy regardless of age.

• FLUOROQUINOLONES: Avoid giving to children. Wait until they are 18 years of age if possible due to risk of possible tendonitis and tendon rupture. So, avoid choosing this as an answer for your adolescents with STDs. If no alternatives are available, you may need a quinolone for a complicated UTI or pyelonephritis. A quinolone may also be used as a second-line treatment for chlamydia pneumoniae. Lastly, ciprofloxacin is a first-line treatment for Shigella. As an FYI, evidence is now starting to suggest that avoiding quinolones in children may not be needed.
• ERYTHROMYCIN: Do not use in children younger than 6 weeks of age due to an association with pyloric stenosis. The association is strong especially during the first two weeks of life. Instead, use azithromycin. Azithromycin is also associated with pyloric stenosis, but the risk is higher with erythromycin.

PENICILLIN

Yes! Penicillin is still the TREATMENT OF CHOICE for Streptococcal pharyngitis, dental infections, and dental-related infections (including parotiditis). It’s also used for syphilis and CAN be used for other infections if the bacteria is sensitive to it.

• PENICILLIN ALLERGY: Most patients who claim to have this allergy do not have a true allergy. If skin testing has been done and confirms the allergy, do not give penicillins or cephalosporins. If no testing has been done, look for other options. If no other options are available, choose a cephalosporin since the likelihood of a concurrent cephalosporin allergy is less than 10%.

CLINDAMYCIN

Clindamycin is active against most gram positives. It does have some MRSA coverage.

PEARL: It is NOT active against Enterococcus.

VANCOMYCIN, LINEZOLID, AND AMPICILLIN

Don’t you DARE pick anything other than vancomycin, linezolid, or ampicillin to cover for ENTEROCOCCUS! Ampicillin actually covers it better than vancomycin!

PEARL: Enterococcus is also covered by rifampin and quinolones, but hopefully that will not be tested. Know that it is NOT covered by cephalosporins.