A 6-month-old vaccinated infant arrives in the ED with a 12-hour history of poor feeding, emesis, and irritability. On exam, she is ill-appearing with T 39.2 C, P 160 bpm, R 40 bpm, BP 80/50 mmHg. CBC shows WBC 11.2, Hgb 13.5, Plt 250. Urinalysis shows > 100 WBC per hpf, positive leukocyte esterase, and positive nitrites. She has no history of prior urinary tract infection. Chest x-ray is negative. Urine and blood cultures are pending. After bringing her fever down, she is still uninterested in drinking, but her exam improved, and you are confident she does not have meningitis, so an LP is not performed.
Which of the following is the best next step in management?

A. Oral ampicillin
B. Oral ampicillin + gentamicin
C. Intravenous ciprofloxacin
D. Intravenous ceftriaxone
E. Intravenous piperacillin + tazobactam

D. Intravenous ceftriaxone

Explanation:

Intravenous ceftriaxone

This patient's presentation is suggestive of a UTI. Given the ill appearance, vital signs, and white count, Upper tract disease (pyelonephritis) should be strongly considered. A parenteral (IV/IM) third-generation cephalosporin is the best choice of those listed for pyelonephritis, given its excellent gram negative coverage (except for Pseudomonas).

INTRAVENOUS CEFTRIAXONE

Explanation: To understand the question very well,let's critically look at the age of the infant and the presenting signs and symptoms.

The infant has a history of poor feeding,emesis(vomitting) and also there is history of irritability.there is also fever.when you look at all these,it is closely related to the signs and symptoms presented by infants with UTI ( urinary tract infection) but when you consider the vital signs of the infant (Temperature: 39.2°c, Respiratory: 40bpm,and Blood pressure: 80/50mmHg), the white blood cell count and the I'll looking appearance of the infant,

Upper tract disease that is (pyelonephritis) should be considered more because the signs and symptoms indicative of pyelonephritis are more strong than that of UTI.

Looking at the age of the infant and the severity of the presenting signs and symptoms, parenteral drug administration(intravenous/intramuscular) will act faster and will be easily absorbed and as well as easily accepted by the infant than enteral adminstration.

Looking at the options listed in the question,ceftriaxone is a third generation cephalosporin (a class of antibiotics used to treat varieties of bacteria infections) and it is so far the best drug in the treatment of pyelonephritis and also the best from the options given in the question,it's effectiveness is seen in the fact that it's gram negative coverage is excellent except in the case of pseudomonads where there is no encouraging gram negative coverage.

multiply it by 5 in order for you to understand i cant give an exact answer.