Final answer:
In ophthalmia neonatorum, the most dangerous causative organism is Neisseria gonorrhoeae. This bacterium can cause serious eye infections in newborns, potentially leading to vision loss or permanent blindness if untreated, which is why antibiotic prophylaxis is administered to newborns.
Step-by-step explanation:
In ophthalmia neonatorum, the most dangerous causative organism is Neisseria gonorrhoeae. This bacterium, which causes gonorrhea, can lead to gonococcal ophthalmia neonatorum, a serious eye infection in newborns. The infection is contracted when the baby passes through the birth canal of a mother infected with N. gonorrhoeae. If left untreated, this condition can cause significant damage to the cornea and potentially result in vision loss or permanent blindness. To prevent such complications, it is standard practice to administer antibiotic creams or drops such as erythromycin to all infants' eyes shortly after birth.
Chlamydia trachomatis also causes inclusion (chlamydial) conjunctivitis but is generally considered less severe than the infection caused by N. gonorrhoeae. Nonetheless, both pathogens are taken very seriously, and the infections they cause are treated aggressively with oral or intravenous antibiotics to prevent the spread of infection and safeguard the infants' vision.