A 37-week-old infant was delivered by cesarean section and discharged from a Connecticut hospital when he was 10 days old. Two days later he was lethargic and had a fever. When he was readmitted to the hospital, he had multiple brain abscesses caused by Citrobacter diversus. After a prolonged illness, the baby died. A second infant with a normal pregnancy and delivery died of C. diversus meningitis after a short illness. Nine infants in the hospital nursery had umbilical cord colonization by C. diversus. Environmental cultures were negative for hospital equipment.

(a) What is the normal habitat of this gram-negative, facultatively anaerobic, non-endospore-forming, lactose-positive rod?

(b) Provide a plan for identifying the source of infection and preventing further infection.

A. We can deduce that microorganisms such as Citrobacter have a classification from which it is possible to establish the most favorable environment for it, since being gram-negative, lactose positive, optional anaerobic, not endospore, it will prefer the environment as humid sites and that contain wastewater and soil as well as the intestine, it can therefore remain in some contaminated food and be transmitted with consumption

B. Given the aforementioned characteristics of Citrobacter, it does not infect all people and prefers those who have deficits in its defense mechanisms, thus it becomes a favorable site for colonization of newborns, who do not have adequate immunity, according to the case. Clinically, the neonate was able to acquire the infection in various ways, although the medical personnel who have manipulated it do not have positive tests, the microorganism can adhere to contaminated surfaces and it will be necessary to take samples of the mother's and neonate's feces, as well as the soil. and the water where the infected was, to subsequently carry out disinfection processes in the areas and avoid new infections.