Again, the medical history and physical examination will frequently reveal the source of infection. Viral illnesses, including respiratory infections and gastroenteritis, account for the majority of febrile illnesses and usually have system-specific symptoms, such as vomiting, diarrhea, rhinorrhea, cough, or rashes. In this age group, such symptoms are more often indicative of an organ-specific infection. Bacterial infections of the respiratory tract include most notably otitis media, pharyngitis, and pneumonia. Otitis media is generally caused by Streptococcus pneumoniae or Haemophilus influenzae, and antibiotic therapy, such as amoxicillin, should be directed at these organisms.27 Although pneumonia is commonly of viral etiology, it is appropriate to institute antibiotic therapy with amoxicillin or erythromycin. The physical signs of meningitis, such as nuchal rigidity and Kernig or Brudzinski signs, may be inapparent in children even up to the age of 2 years. A bulging fontanelle, vomiting, irritability that increases when the infant is held, inconsolability, or a febrile seizure may be the only signs suggestive of meningitis. Infants with aseptic meningitis should generally be hospitalized and ensured adequate long-term follow-up because they are at higher risk for subsequent neurologic and learning disabilities. The presence of petechiae on physical examination should alert physicians to the potential presence of a serious underlying infection. Up to 20 percent of children may have bacteremia or meningitis most frequently with Neisseria meningitidis or H. influenzae.2 29 Petechiae in association with high fever (340°C), ESR at or above 30 mm/h, and WBCs of at least 15,000/mm3 are most frequently correlated with bacteremia.
Bacteremic infants may or may not have an obvious focus of infection. The height of the fever is a clue to which infants are bacteremic. Although bacteremia may be seen at lower temperatures, a temperature of over 39.5°C (103.1°F) in infants aged 3 to 36 months is associated with a higher incidence of bacteremia. Certain laboratory tests have been recommended to assist in further identifying bacteremic patients. WBCs over 15,000/mm 3, band counts of at least 500/mm3, total polymorphonuclear counts at or above 10,000/mm3, and band plus polymorphonuclear counts equal to or greater than 10,500/mm 3 are associated with an increased incidence of bacteremia, although bacteremia also occurs in the absence of these findings. 30 The incidence of bacteremia in children 3 to 24 months of age with a temperature of 39.5°C (103.1°F) or over is about 5 to 6 percent. The incidence increases to 12 to 15 percent in patients with WBCs of 15,000/mm 3 or over. An ESR at or above 30 mm/h has the same significance as WBCs of 15,000/mm3 or greater.72 26 The organism most commonly causing bacteremia in this age group is S. pneumoniae. Haemophilus influenzae has been rarely implicated in cases of occult bacteremia since the availability of H. influenzae vaccine.
Is it important to perform a blood culture to detect occult bacteremia?31 Opinions vary on the answer to this question. It is apparent that bacteremic patients do better if they receive antibiotics early on.32 Many bacteremic children do have a focus of infection and so are treated anyway. Additionally, in at least 25 percent of bacteremic patients with no focus of infection, the bacteremia is resolved without any antibiotics. Others develop soft tissue infections, which are then appropriately managed. The ability of oral antibiotics to prevent the development of meningitis in bacteremic children is still unclear. The blood culture appears to be useful for following patients who may not be returning for periodic evaluations. Therefore, from a medical and epidemiologic standpoint, blood cultures are indicated in high-risk infants or those in whom the physician suspects an infection.
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This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.