What is the likely diagnosis and treatment for a 10-day-old infant, born at 37 weeks and 1 day gestation without complications, presenting with a red eye and drainage?

Neonatal Conjunctivitis at 10 Days of Age

This 10-day-old infant most likely has either chlamydial or bacterial conjunctivitis, and requires immediate evaluation with conjunctival cultures and Gram stain before initiating treatment—if severe purulent discharge or rapid progression is present, gonococcal conjunctivitis must be ruled out urgently as it can cause corneal perforation within 24-48 hours. 1, 2

Differential Diagnosis Based on Timing and Clinical Features

The timing of onset at 10 days is critical for narrowing the differential:

• Chlamydial conjunctivitis (most likely at this age) manifests 5-19 days following birth and presents with eyelid edema, bulbar conjunctival injection, and discharge that may be purulent, mucopurulent, or blood-stained 2
• Gonococcal conjunctivitis typically manifests within 1-7 days after birth with marked eyelid edema, severe purulent discharge, and bulbar conjunctival injection—though it can occasionally present later 2
• Bacterial conjunctivitis from other organisms (H. influenzae, S. pneumoniae) can occur at any time and presents with purulent discharge and mattering of the eyelids 3

Immediate Assessment Required

You must evaluate for these critical red flags that require immediate ophthalmology referral:

• Severe or rapidly reaccumulating purulent discharge after cleaning 2
• Corneal involvement (infiltrate, ulcer, or opacity) using fluorescein staining 1, 2
• Moderate to severe eye pain or marked irritability 2
• Eyelid vesicles (suggesting HSV) 2
• Preauricular lymphadenopathy 1

Diagnostic Workup

Before initiating treatment, obtain:

• Conjunctival cultures and Gram stain to identify the causative organism 1, 4
• Fluorescein staining to detect corneal involvement 1
• Assessment of discharge character and severity 2

The microbiologic work-up with cytology, cultures, and microbial sensitivities is mandatory in neonatal conjunctivitis 4

Treatment Algorithm

If Gonococcal Conjunctivitis is Suspected (severe purulent discharge, rapid progression):

• Administer Ceftriaxone 125 mg IM immediately for infants weighing less than 45 kg 1
• Add topical antibiotics and saline lavage for comfort and faster resolution 1
• Daily follow-up is mandatory until complete resolution 1, 5
• The infant is considered non-infectious after 24 hours of appropriate antibiotic therapy 5
• Mothers and sexual partners must be evaluated and treated 1
• Consider sexual abuse in all cases 1

If Chlamydial Conjunctivitis is Suspected or Confirmed:

• Erythromycin base or ethylsuccinate 50 mg/kg/day orally divided into 4 doses for 14 days 1
• Treatment efficacy is approximately 80%, and a second course may be required 1
• Topical antibiotics are unnecessary when systemic treatment is given 1
• More than 50% of infants with chlamydial conjunctivitis may also be infected at other sites (nasopharynx, genital tract, or lungs), making systemic therapy essential 1
• Follow-up is essential to confirm treatment success 1
• Mothers and sexual partners must be evaluated and treated 1

If Uncomplicated Bacterial Conjunctivitis:

• A 5-7 day course of broad-spectrum topical antibiotic applied 4 times daily 1
• Treatment reduces symptom duration from 7 days to 5 days 1
• Return for evaluation if no improvement after 3-4 days of treatment 1

Critical Management Considerations

Common pitfalls to avoid:

• Missing gonococcal or chlamydial infection, which require systemic therapy and have serious sequelae including corneal scarring and perforation 1
• Indiscriminate use of topical antibiotics or corticosteroids 1
• Delayed referral when there are signs of severe infection or lack of improvement 1
• Not considering the possibility of child abuse in cases of potentially sexually transmitted ocular disease 1

Infection Control

• Bacterial conjunctivitis remains infectious until approximately 24-48 hours after starting appropriate antibiotic treatment 5
• Strict hand hygiene before and after touching the infant's eyes is essential 1, 5
• Use separate towels and washcloths, and properly dispose of contaminated materials 5
• The infant should not attend daycare until they have received 24 hours of appropriate antibiotic treatment 5

Coordination of Care

Infants who require systemic treatment are best managed in conjunction with a pediatrician 1, particularly given the high rate of concurrent infections at other sites with chlamydial disease and the need for parental evaluation and treatment.