ABP Pediatric Infectious Diseases cheat sheet

Group A streptococcal pharyngitis: penicillin V or amoxicillin 50 mg/kg once daily (max 1 g) for a full 10 days; the long course is required to prevent acute rheumatic fever, and penicillin resistance has not emerged.

Pertussis: azithromycin 10 mg/kg on day 1 then 5 mg/kg days 2–5; droplet precautions continue until 5 days of effective therapy; household contacts receive the same azithromycin prophylaxis regimen.

Diphtheria: equine antitoxin plus azithromycin or penicillin G, with strict droplet precautions and public health notification; antitoxin must never be delayed for culture confirmation.

Lyme disease: erythema migrans is treated with doxycycline 4.4 mg/kg/day divided twice daily (max 100 mg/dose) for 10–14 days; doxycycline is acceptable in children of all ages for tick-borne disease.

Latent tuberculosis: 4 months of daily rifampin (ages 2–11 years with a susceptible source case), 12 weeks of weekly isoniazid plus rifapentine (age ≥2 years), or 6–9 months of daily isoniazid.

Tuberculous meningitis: four drugs (isoniazid, rifampin, pyrazinamide, plus ethambutol or an aminoglycoside) for 12 months, with dexamethasone 0.15 mg/kg every 6 hours for 4 days then tapered.

Meningococcal postexposure prophylaxis: rifampin 10 mg/kg (5 mg/kg if under 1 month) every 12 hours for 2 days, single-dose ciprofloxacin, or single-dose ceftriaxone; index cases treated with ceftriaxone need no prophylaxis.

Skin abscess: incision and drainage alone is sufficient for small abscesses without systemic signs; add clindamycin or trimethoprim-sulfamethoxazole for extensive disease, failed drainage, or systemic toxicity.

Influenza: oseltamivir is most effective within 48 hours of onset, but hospitalized children and those at high risk for complications are treated regardless of symptom duration.

Neonatal and childhood HSV disease: acyclovir 20 mg/kg every 8 hours intravenously for 14 days in skin-eye-mouth disease and 21 days in CNS or disseminated disease; start empirically before PCR results return.

Congenital CMV: valganciclovir 16 mg/kg twice daily for 6 months improves hearing and neurodevelopmental outcomes in symptomatic infants with CNS involvement (chorioretinitis, hearing loss, microcephaly).

Measles: airborne precautions until 4 days after rash onset; MMR within 72 hours of exposure for eligible contacts, or immune globulin within 6 days for infants under 12 months, pregnant women, and severely immunocompromised children.

Parvovirus B19: causes transient aplastic crisis in chronic hemolytic anemias and hydrops fetalis after maternal infection; patients with aplastic crisis require droplet precautions during hospitalization.

RSV bronchiolitis: supportive care only-no routine bronchodilators, corticosteroids, or antibiotics; nirsevimab or palivizumab is reserved for high-risk infants during RSV season.

Varicella: airborne plus contact precautions until all lesions are crusted; acyclovir is indicated for adolescents older than 12 years, high-risk hosts, and complicated disease.

Dengue: NS1 antigen is detectable in the first 0–5 days; monitor for plasma leakage during defervescence using rising hematocrit, falling platelets, and narrowing pulse pressure.

Candidemia: an echinocandin (micafungin or caspofungin) is first-line therapy; remove central venous catheters, obtain a dilated retinal examination, and repeat blood cultures until sterile.

Invasive aspergillosis: serum or BAL galactomannan supports diagnosis; voriconazole is first-line therapy with isavuconazole as an alternative; combination therapy is not routine.

Cryptococcal meningitis in HIV: amphotericin B deoxycholate plus flucytosine for 2 weeks followed by fluconazole; perform serial lumbar punctures when opening pressure exceeds 25 cm H2O.

Pneumocystis jirovecii pneumonia: trimethoprim-sulfamethoxazole 15–20 mg/kg/day of the trimethoprim component divided every 6–8 hours for 21 days; add corticosteroids when PaO2 is below 70 mmHg.

Severe malaria: intravenous artesunate 2.4 mg/kg at 0, 12, and 24 hours then daily; uncomplicated malaria is treated with a 3-day artemisinin-based combination such as artemether-lumefantrine.

Giardiasis: tinidazole as a single dose or metronidazole for 5–7 days; stool antigen enzyme immunoassay is more sensitive than microscopy; treat only symptomatic household contacts.

Pinworm: albendazole or pyrantel pamoate as a single dose repeated in 2 weeks, with simultaneous treatment of all household members and laundering of bedding to prevent reinfection.

Toxoplasmosis: pyrimethamine plus sulfadiazine with leucovorin rescue; trimethoprim-sulfamethoxazole is an alternative for mild disease or when sulfadiazine is unavailable.

Intrapartum group B streptococcal prophylaxis: penicillin G 5 million units intravenously then 2.5–3 million units every 4 hours; cefazolin for non-anaphylactic penicillin allergy; clindamycin or vancomycin only with confirmed susceptibility.

Early-onset neonatal sepsis: ampicillin plus gentamicin; add cefotaxime or another third-generation cephalosporin when meningitis is suspected because gentamicin penetrates CSF poorly.

Congenital syphilis: aqueous crystalline penicillin G 50,000 units/kg/dose intravenously every 12 hours in the first week of life and every 8 hours thereafter for 10 days; a single dose of benzathine penicillin is adequate only for proven uncomplicated cases.

Congenital CMV must be documented by urine or saliva CMV PCR within the first 3 weeks of life; testing after 3 weeks cannot distinguish congenital from perinatally acquired infection.

Neonatal HSV evaluation includes surface PCR or culture at 24–48 hours, CSF PCR, and serum ALT; a normal initial evaluation does not exclude disease, so empiric acyclovir is continued pending results.

Infant HIV: maternal antibody causes false-positive antibody tests until 18 months, so diagnosis relies on HIV DNA or RNA PCR at 14–21 days, 1–2 months, and 4–6 months of age.

Perinatal hepatitis B: infants of HBsAg-positive mothers receive vaccine plus hepatitis B immune globulin within 12 hours of birth; check HBsAg and anti-HBs at 9–12 months after completing the series.

Neonatal conjunctivitis timing: chemical irritation within 24 hours, gonococcal at 2–5 days, chlamydial at 5–14 days; gonococcal disease requires ceftriaxone and evaluation for disseminated infection.

DTaP is given at 2, 4, 6, and 15–18 months; the fourth dose must be at least 12 months of age and 6 months after the third dose; Tdap booster is given at 11–12 years.

MMR: first dose at 12–15 months and second at 4–6 years, separated by at least 28 days; a dose given at 6–11 months for travel does not count toward the routine series.

Hepatitis B vaccine: monovalent birth dose within 24 hours for all infants, with hepatitis B immune globulin given within 12 hours when the mother is HBsAg positive.

Rotavirus vaccine: first dose by 14 weeks 6 days of age and the final dose by 8 months 0 days; doses administered beyond these limits are not recommended because of intussusception risk.

Influenza vaccine is recommended from 6 months of age annually; children 6 months through 8 years receiving it for the first time or with only one prior dose need 2 doses at least 4 weeks apart.

PCV is given as a 4-dose series at 2, 4, 6, and 12–15 months; PPSV23 is added for children 2 years and older with high-risk conditions such as asplenia or chronic lung disease.

Live vaccines (MMR, varicella, rotavirus, live influenza) are contraindicated in pregnancy, severe immunocompromise including SCID, and after high-dose corticosteroids.

HPV vaccine: 2 doses when the series begins before the 15th birthday, 6–12 months apart; 3 doses when starting at 15 years or older or in immunocompromised patients.

Absolute neutrophil count = WBC × (percent neutrophils + percent bands); severe neutropenia is defined as ANC below 500 cells/microL, and the risk of bacterial sepsis rises steeply below 100.

Febrile neutropenia: begin an anti-pseudomonal beta-lactam (cefepime, piperacillin-tazobactam, or meropenem) within 60 minutes; add vancomycin for hypotension, suspected catheter infection, or MRSA colonization.

Asplenia or complement deficiency: encapsulated organisms (Streptococcus pneumoniae, Haemophilus influenzae type b, Neisseria meningitidis) cause overwhelming sepsis; provide penicillin prophylaxis, full vaccination, and ceftriaxone for any fever.

Chronic granulomatous disease: catalase-positive organisms predominate-Staphylococcus aureus, Aspergillus, Serratia, Burkholderia, Nocardia, Chromobacterium; prophylaxis is trimethoprim-sulfamethoxazole plus itraconazole.

Terminal complement (C5–C9) deficiency: recurrent Neisseria bacteremia and meningitis; screen with CH50 and vaccinate against meningococcus, including MenB.

Severe combined immunodeficiency: lymphopenia, absent thymic shadow, and positive TREC newborn screen; live vaccines are contraindicated and hematopoietic stem cell transplant is curative.

HIV: antiretroviral therapy for all children; trimethoprim-sulfamethoxazole prophylaxis for Pneumocystis begins at CD4 below 15% in young children or below 200 cells/microL in older children.

Transplant recipients: trimethoprim-sulfamethoxazole prophylaxis against Pneumocystis for at least 6 months, CMV monitoring with preemptive therapy, and vigilance for Epstein-Barr virus–driven post-transplant lymphoproliferative disease.

Vancomycin: target an AUC24/MIC of 400–600 mg·h/L for serious infections; trough-only monitoring of 15–20 mcg/mL is an acceptable surrogate when AUC cannot be calculated.

Aminoglycosides: extended-interval once-daily dosing is standard; monitor trough concentrations (goal below 1 mcg/mL for gentamicin) and renal function rather than peak levels.

Beta-lactam allergy: true cross-reactivity between penicillins and later-generation cephalosporins is about 1–2%; avoidance is warranted only after anaphylaxis to a cephalosporin sharing an identical R1 side chain.

Procalcitonin rises within 2–6 hours of bacterial infection, peaks at 12–24 hours, and has a half-life of 24–35 hours; low or falling values support discontinuation of antibiotics.

Standard durations: uncomplicated community-acquired pneumonia and uncomplicated bacteremia 5–7 days when the patient is afebrile and clinically improving; group A streptococcal pharyngitis requires 10 days.

Clostridioides difficile infection: oral vancomycin or fidaxomicin is first line; metronidazole is reserved for situations when preferred agents are unavailable because it achieves lower cure rates.

Fluoroquinolones are reserved for specific indications in children (such as Pseudomonas in cystic fibrosis) because of concerns about tendon, musculoskeletal, and CNS adverse effects.

Therapeutic drug monitoring is required for vancomycin, aminoglycosides, voriconazole (trough 1–5.5 mcg/mL), and posaconazole; beta-lactams generally do not require routine monitoring.

Blood culture yield depends on volume: 1–3 mL per bottle for infants and up to 10 mL per bottle for older children; inadequate volume is the leading cause of falsely negative cultures.

CSF in bacterial meningitis: white cells above 1000/microL with more than 80% neutrophils, glucose ratio below 0.4, and protein above 100 mg/dL (normal neonatal protein can reach 170 mg/dL).

Gram stain sensitivity falls sharply when bacterial density is below 10^4 CFU/mL; a negative Gram stain never excludes infection, and culture remains the reference standard.

Urine culture in infants: obtain by catheterization or suprapubic aspiration; a catheter specimen growing at least 50,000 CFU/mL of a single organism is diagnostically significant, whereas bag specimens are unreliable.

Rapid antigen testing for group A Streptococcus has specificity above 95% but sensitivity of 70–90% in children; a negative rapid test in a child requires throat culture confirmation.

Tuberculosis: nucleic acid amplification (Xpert MTB/RIF) provides results within hours and detects rifampin resistance, but culture remains the gold standard and takes 2–6 weeks.

HIV diagnosis in children older than 18 months uses fourth-generation antigen/antibody testing with differentiation; infants require virologic testing because maternal antibody persists.

Respiratory virus detection by multiplex PCR on nasopharyngeal swabs is more sensitive than culture or antigen testing and results in more appropriate isolation and antiviral decisions.

Contact precautions (gown and gloves) are required for MRSA, VRE, Clostridioides difficile, RSV, scabies, and draining wound infections; hand hygiene is performed before and after every contact.

Droplet precautions apply to influenza, pertussis, mumps, rubella, diphtheria, and Neisseria meningitidis; use a mask and keep the patient in a single room when possible.

Airborne precautions require a negative-pressure room and N95 respirator for pulmonary tuberculosis, measles, varicella, and smallpox because these pathogens travel on small droplet nuclei.

Clostridioides difficile: wash hands with soap and water because alcohol-based rubs do not kill spores; use a sporicidal environmental agent and continue contact precautions until diarrhea resolves.

Isolation duration rules: measles until 4 days after rash onset, varicella until all lesions are crusted, pertussis until 5 days of effective therapy, and meningococcus until 24 hours of effective therapy.

Central line–associated bloodstream infection prevention bundles include hand hygiene, maximal sterile barrier during insertion, chlorhexidine antisepsis, and daily review of line necessity.

Surgical site infection prevention: cefazolin within 60 minutes before incision (vancomycin when MRSA is a concern), with redosing for long procedures and avoidance of razor shaving.

Occupational needlestick exposures: HIV postexposure prophylaxis should begin within hours (ideally under 2 hours) and continue 28 days; hepatitis B status of the source and the worker determines further management.

Febrile infant younger than 3 months with a rectal temperature of 38.0°C or higher: full sepsis evaluation including blood, urine, and CSF cultures with empiric intravenous antibiotics pending results.

Kawasaki disease: fever for at least 5 days plus 4 of 5 features (rash, conjunctivitis, oral changes, extremity changes, cervical lymphadenopathy); treat with IVIG 2 g/kg and aspirin, with echocardiography at baseline and follow-up.

Acute otitis media: high-dose amoxicillin 80–90 mg/kg/day divided twice daily; observation with close follow-up is an option for children 6–23 months with nonsevere unilateral disease.

Bacterial sinusitis: symptoms lasting 10 days or more, severe onset, or worsening after improvement; amoxicillin-clavulanate is preferred when the child has recently received antibiotics.

Community-acquired pneumonia: amoxicillin is first line for typical bacterial pneumonia; add a macrolide for children 5 years and older when atypical (Mycoplasma) infection is suspected.

Febrile urinary tract infection in a child 2–24 months: parenteral ceftriaxone or cefotaxime for 2–3 days followed by oral therapy to complete 7–10 days, plus renal ultrasound for children under 2 years.

Bacterial meningitis: neonates receive ampicillin, cefotaxime, and gentamicin; children beyond the neonatal period receive vancomycin plus ceftriaxone with dexamethasone 0.15 mg/kg every 6 hours for 2 days.

Fever in a child with sickle cell disease: obtain cultures and give ceftriaxone immediately; functional asplenia makes encapsulated organisms, especially Streptococcus pneumoniae, rapidly lethal.