Group B streptococcal diseaseDownloads

An 18-month-old boy presents to the emergency department for malaise. The boy’s parents report worsening fatigue for 3 days with associated irritability and anorexia. The patient’s newborn screening revealed a point mutation in the beta-globin gene but the patient has otherwise been healthy since birth. On physical exam, his temperature is 102.4°F (39.1°C), blood pressure is 78/42 mmHg, pulse is 124/min, and respirations are 32/min. The child is tired-appearing and difficult to soothe. Laboratory testing is performed and reveals the following: Serum: Na+: 137 mEq/L Cl-: 100 mEq/L K+: 4.4 mEq/L HCO3-: 24 mEq/L Urea nitrogen: 16 mg/dL Creatinine: 0.9 mg/dL Glucose: 96 mg/dL Leukocyte count: 19,300/mm^3 with normal differential Hemoglobin: 7.8 g/dL Hematocrit: 21% Mean corpuscular volume: 82 um^3 Platelet count: 324,000/mm^3 Reticulocyte index: 3.6% Which of the following is the most likely causative organism for this patient's presentation?

A 3100-g (6.9-lb) male newborn is brought to the emergency department by his mother because of fever and irritability. The newborn was delivered at home 15 hours ago. He was born at 39 weeks' gestation. The mother's last prenatal visit was at the beginning of the first trimester. She received all standard immunizations upon immigrating from Mexico two years ago. Seven weeks ago, she experienced an episode of painful, itching genital vesicles, which resolved spontaneously. Four hours before going into labor she noticed a gush of blood-tinged fluid from her vagina. The newborn is ill-appearing and lethargic. His temperature is 39.9°C (103.8°F), pulse is 170/min, respirations are 60/min, and blood pressure is 70/45 mm Hg. His skin is mildly icteric. Expiratory grunting is heard on auscultation. Skin turgor and muscle tone are decreased. Laboratory studies show: Hemoglobin 15 g/dL Leukocyte count 33,800/mm3 Platelet count 100,000/mm3 Serum glucose 55 mg/dL Which of the following is the most likely causal organism?