Infectious Disease

Preschool-aged children with CAP (community acquired pneumonia) frequently do not require antibiotics, as most disease is caused by viral infections.  Children with suspected CAP of bacterial origin should usually receive amoxicillin for outpatient treatment, or ampicillin or penicillin G for inpatient treatment. These agents have sufficient activity against the common bacterial pathogens causing CAP without being unnecessarily broad. Third-generation cephalosporins should be reserved for children who are unimmunized or with severe infection, or where there are high rates of penicillin-resistance among invasive pneumococcal isolates. Additional agents may be indicated in cases of suspected staphylococcal pneumonia, atypical pathogens, or influenza.

Bacterial growth in cultures of bag urine specimens are more likely to be falsely positive in young children with suspected urinary tract infection (UTI) due to contamination with perineal flora. A bag urine culture cannot therefore be used to establish the diagnosis of UTI and may lead to overtreatment. Although a negative bag culture would rule out a UTI, a positive culture requires confirmation by a more specific method, incurring substantial delay. Cultures of urine specimens obtained by catheterization or suprapubic aspiration are more specific and as such are preferred as the routine method of urine collection in non-toilet trained children. Clean-catch, the standard technique of urine collection for toilet-trained children, is a non-invasive method sometimes attempted in infants but is also associated with relatively high rates of contamination.

Infants are commonly asymptomatic carriers of C. difficile (14-63%), but clinical illness is rarely reported before 12-24 months of age. It has been hypothesized that infants lack the cellular machinery for Clostridium toxin internalization. When investigating an infant with diarrhea, alternative diagnoses should be considered even with a positive test for C. difficile. Testing should be limited to immunosuppressed infants or those with underlying intestinal conditions (e.g. Hirschsprung disease, inflammatory bowel disease) when other etiologies have been ruled out. Therefore, it is prudent to avoid routine testing in children less than 12 months, and for children 1-3 years of age, test for other causes of diarrhea first, particularly viral.

Large retrospective cohort studies have shown no difference in treatment failure rate between children with uncomplicated acute hematogenous osteomyelitis treated with prolonged IV therapy when compared with shorter IV therapy and early transition to oral, to complete the course of therapy. “Prolonged” IV therapy definitions varied and ranged from 7 days or more in one cohort to the entire treatment course of 3 to 6 weeks in another. Of note, complications with PICC lines in the prolonged treatment arms were seen at a rate between 3-15%. Consideration for use of prolonged IV therapy is in complicated disease (significant bone destruction; resistant or unusual pathogen; immunocompromised patient; sepsis or septic shock; venous thrombosis; metastatic foci or important abscess formation). Guidance as to when to consider transition to oral therapy includes a good clinical response and consideration of the following: afebrile for 48-72 hours; normalization of inflammatory markers or decrease in CRP by 50%; absence of complications or metastatic foci; and negative blood culture if culture was initially positive.

Antimicrobials such as fluoroquinolones, trimethoprim-sulfamethoxazole, clindamycin, linezolid, metronidazole and fluconazole have excellent bioavailability and only rarely need to be administered intravenously. Use of oral formulations of these medications reduces the need for placement and maintenance of venous access devices and their associated complications.

Reported penicillin reactions frequently result in the use of alternate second-line agents that may be clinically inferior or may pose increased risks to patients resulting in longer lengths of stay and increased costs of care. Alternate broad-spectrum agents may also result in increased rates of adverse events and selection for antimicrobial resistance. Therefore, it is important to obtain a detailed history of a patient’s reported prior reaction to penicillin to determine whether beta-lactam therapy can be safely administered.

The 2014 recommendations of the International Antiviral Society – US Panel state that measurement of CD4 count is optional among patients with suppressed viral loads for >2 years and CD4 counts >500/µL. CD4 measurement in these patients is of low-value and may create unnecessary patient concern in response to normal variation of CD4 counts. In prospective studies of patients who have responded to antiretroviral therapy with HIV-1 RNA suppression and rises in CD4 cell count >200 cells/μL, there was little clinical benefit from continued routine measurement of CD4 counts.

There is poor correlation between clinical response and resolution of findings on magnetic resonance imaging (MRI), computed tomography (CT), and nuclear studies in patients with osteomyelitis. Because radiologic resolution may lag behind clinical improvement, repeat imaging may lead to unnecessary prolongation of antimicrobial therapy. Repeat imaging is indicated in cases where there is a lack of clinical response, progression of clinical findings, or the presence of an undrained abscess on the initial scan.

The addition of an aminoglycoside such as gentamicin to beta-lactam therapy or vancomycin for treatment of bacteremia or native valve infective endocarditis caused by Staphylococcus aureus has not been demonstrated to improve clinical outcomes. This practice may result in adverse effects including acute kidney injury and ototoxicity. The addition of gentamicin is still recommended in cases of prosthetic valve endocarditis caused by Staphylococcus aureus.