Полезные материалы за все 6 курсов / Учебники, методички, pdf / Kaplan Pediatrics USMLE 2CK 2021

INFECTIONS

Neonatal Sepsis

A 3-week-old infant presents with irritability, poor feeding, temperature of 38.9 C (102 F), and grunting. Physical examination reveals a bulging fontanel, delayed capillary refill, and grunting.

•Signs and symptoms are very nonspecific.

•Risk factors

–Prematurity

–Chorioamnionitis

–Intrapartum fever

–Prolonged rupture of membranes

•Early onset: first week of life; maternal factors

–Chorioamnionitis

–Organisms: group B Streptococcus, E. coli, Listeria monocytogenes

•Late onset: second week through end of neonatal period; hospital or communityacquired organisms (if still hospitalized: iatrogenic infection)

–Most common organism: coagulase negative S. aureus (epidermidis)

•Diagnosis—sepsis workup: CBC, differential and platelets, blood culture, urine analysis and culture, chest x-ray; lumbar puncture only for neonates with severe signs (lethargy, hypothermia, hypotonia, poor perfusion, apnea, abnormal neurological­ findings, or clinical deterioration from birth)

•Treatment

–If no evidence of meningitis: ampicillin and aminoglycoside until 48–72-hour cultures are negative

–If meningitis or diagnosis is possible: ampicillin and third-generation cephalosporin (not ceftriaxone)

Note

In recent years studies have proven that in the first year of life, lumbar puncture reveals almost no cases of meningitis. Therefore, lumbar puncture should be reserved only for neonates with severe signs.

Note

Toxoplasmosis

Other (syphilis, varicella, HIV, and parvovirus B19)

Rubella Cytomegalovirus (CMV) Herpes

Transplacental Intrauterine Infections (TORCH)

TORCH infections are typically acquired in first or second trimester. Most infants have IUGR.

Toxoplasmosis

Toxoplasmosis is a maternal infection worldwide, due primarily to ingestion of undercooked or raw meat containing tissue cysts. Ingestion of water or food with oocytes that have been excreted by infected cats (fecal contamination) is the most common form of transmission in the United States. Advise pregnant women not to change/clean cat litter while pregnant.

•Findings

–Jaundice, hepatosplenomegaly

–Thrombocytopenia, anemia

–Microcephaly

–Chorioretinitis

–Hydrocephalus

–Intracranial calcifications

–Seizures

•Outcomes

–Psychomotor retardation

–Seizure disorder

–Visual impairments

•Treatment—maternal treatment during pregnancy reduces the likelihood of transmission significantly (spiramycin)

–Infants are treated with pyrimethamine, sulfadiazine, and leucovorin.

phil.cdc.gov

Figure 1-3. Congenital Cataract Secondary to Maternal Rubella Infection

Learning Objectives

Demonstrate understanding of chromosome abnormalities

Solve problems concerning early overgrowth with associated defects, defects with facial features as the major defect, osteochondrodysplasias, and disorders of connective tissue

Explain information related to unusual brain and/or neuromuscular findings with associated defects

ABNORMALITIES OF CHROMOSOMES

Trisomy 21 (Down Syndrome)

Down syndrome is the most common pattern of human malformation.

•Genetics

–94% full trisomy 21(nondisjunction); risk of recurrence 1–2% and then increases with advancing maternal age

–4–6% with translocation; most are new mutations but must obtain parental karyotypes for possible balanced translocation carrier

•Findings

–Upward slanting palpebral fissures; speckling of iris (Brushfield spots); inner epicanthal folds

–Small stature, mouth open with tongue protrusion; mild microcephaly, short neck, flat occiput, short metacarpals and phalanges; single palmar crease

–Hypotonia

–Hearing loss (sensorineural, conductive, and mixed)

–Primary gonadal deficiency

–Cardiac anomaly—ECD > VSD > PDA, ASD; also MVP

–GI anomalies: duodenal atresia, Hirschsprung

–Atlanto-axial instability

–Hypothyroidism

–Acute lymphocytic leukemia (but acute myeloblastic leukemia if in first 3 years of life)

–Intellectual disability, variable

Cardiac Abbreviations

ASD: atrial septal defect

ECD: endocardial cushion defect

MVP: mitral valve prolapse

PDA: patent ductus arteriosus

VSD: ventricular septal defect

Klinefelter Syndrome (XXY)

•Genetics; most common findings manifested at puberty

•Findings

–Decreased IQ (average IQ 85−90)

–Behavioral/psychiatric problems

–Long limbs (decreased upper:lower segment ratio)

–Slim (weight/height ratio low)

–Hypogonadism and hypogenitalism (testosterone replacement at age 11−12 years) = hypergonadotropic hypogonadism (increased FSH and LH, and decreased testosterone)

–Infertility in almost all

–Gynecomastia

Turner Syndrome (XO)

•Genetics

–Generally sporadic; no older maternal age seen

–Paternal chromosome more likely to be missing

–Many mosaic patterns (including Y-chromatin)

•Findings

–Small-stature female

–Absence of one SHOX gene (short stature homeobox; embryonic regulation of skeletal system, especially arms and legs)

–Abnormal GH–IGF receptor axis

–Gonadal dysgenesis–streak ovaries in XO

–Average IQ 90

–Congenital lymphedema, residual puffiness over dorsum of fingers and toes

–Broad chest, wide-spaced nipples

–Low posterior hairline; webbed posterior neck

–Cubitus valgus (elbow) and other joint problems

–Horseshoe kidney and other renal defects

–Cardiac:

°Bicuspid aortic valve (number 1 cardiac anomaly)

°Coarctation (Turner syndrome is the condition in which this is seen most often, but it is not the most common cardiac condition in Turner syndrome)

°Aortic stenosis, mitral valve prolapse

°Hypertension common, even without cardiac or renal disease

–Primary hypothyroidism, mostly autoimmune, and other autoimmune diseases (celiac disease)

•Natural history

–Decreased height velocity with delayed bone age

–Estrogen treatment indicated

–May increase height by 3−4 cm with growth hormone (GH)

Note

Gonadal dysgenesis is not evident in childhood, so chromosomes are warranted in any short-stature female whose phenotype is compatible with Turner syndrome.

Also consider in any adolescent with absent breast development by age 13, pubertal arrest, or primary/secondary amenorrhea with increased FSH.