Serratia marcescens is an anaerobic gram-negative bacillus belonging to the family Enterobacter iaceae. This bacterium has been the offending agent in cases of endophthalmitis following ocular surgery or trauma.1,2 Of the 108 cases of metastatic bacterial endophthalmitis reviewed by 1975, however, none was due to S. marcescens.3 A more recent review of 72 cases of metastatic endophthalmitis observed between the years 1976 and 1985 disclosed that in three instances, bacteria of the Serratia species were identified.4 All occurred in elderly, debilitated patients.4,5 To our knowledge, metastatic endophthalmitis due to S. marcescens in a newborn has not been reported previously.
A ten-day-old full-term baby boy was referred to our hospital because of leukocoria in his right eye and septicemia. Seven days after delivery, a colostomy was performed due to an unperforated anus. Forty-eight hours following surgery he developed high fever, irritability, and severe proptosis of the right eye. On admission we observed marked periorbital Chemosis with a stone-hard proptotic right eye (Figure 1). Slit lamp examination revealed a normal anterior segment in the left eye. Jn the right eye. there was marked ciliary injection, hazy cornea, shallow anterior chamber, mid-dilated pupil non-reactive to light, and leukocoria (Figure 2). Visualization of the posterior pole of the right eye was not possible. The fundus of the left eye was normal. Radiologic evaluation and CT scan revealed a right periorbital soft tissue edema with no definite orbital or sinusal abscess formation.
A tentative diagnosis of septicemia with metastatic endophthalmitis in the right eye was made. Aerobic and anaerobic cultures from blood, cerebrospinal fluid, and vitreous were performed and treatment with cefatoxin 100 mg/kg/d and ampicillin 200 mg/kg/d IV was started. Serratia marcescens was isolated from blood, CSF, and vitreous. Following the sensitivity results, amikacin 15 mg/kg/d was substituted for cefatoxin. Under ampicillin and amikacin, the baby became afebrile and his general condition improved. Repeated blood and CSF cultures at this stage were negative. The proptosis of the right eye increased, however, and the baby remained irritable and agitated. Although the possibility of performing a therapeutic vitrectomy was raised, this alternative was deferred because of clinical appearance, lack of direct and consensual responses to light, and extinguished visual evoked responses to flash stimuli from the right eye. Seven days after admission, enucleation of the right eye was performed and a conformer inserted in the socket. The day following surgery the baby became quiet and behaved normally. He was discharged 1 week later.
FIGURE 1: External appearance, chemosis, and proptosis of the right eye.
FIGURE 2: Right eye demonstrating leukocoria.
FIGURE 3: Saggital section of the enucleated right globe (hematoxylin and eosin, x 3).
FIGURE 4: Higher magnification showing the marked cellular infiltrates invading all ocular coats. S - sclera; C - choroid: R -retina; Vc - vitreous cavity (hematoxylin and eosin, x 125).
Pathologic examination of the globe disclosed a vitreous cavity filled with red-brown fluid containing leukocytes and bacteria of the S. marcescens species (Figure 3). Cultures for fungi and viruses were negative. Microscopically, the cornea, sclera, uveal tract, and optic nerve head were heavily infiltrated with polymorphonuclear cells. The retina was necrotic and had lost its normal architecture (Figure 4).
The prognosis for vision in metastatic endophthalmitis is guarded.3 In cases with involvement of the posterior segment where the vitreal inflammatory reaction prevents fundus visualization, the outcome is generally very poor.6,7 Regardless of treatment modality, loss of useful vision is still the rule in cases of diffuse posterior metastatic endophthalmitis.4 Serratia marcescens as the causative agent of endophthalmitis has been reported in adults, mostly following intraocular foreign body or surgery in elderly patients.1,2,4 More recently, three cases of metastatic endophthalmitis due to S. marcescens have been described.5,8,9 All occurred in elderly patients with impaired immune responses. Our case is the first observed in a newborn. The loss of visual functions of the involved eye is very rapid and may be due to occlusion of the central retinal artery by a septic embolus4 or the release of endotoxins.1
During the few days of follow-up, we faced a dilemma regarding the management of the ocular condition. Eradication of the bacterium from the CNS and peripheral blood by amikacin and ampicillin apparently had no effect on the condition of the right eye. Because of the rapid loss of any detectable visual function and the fear of possibly inducing sympathetic ophthalmia if pars plana vitrectomy10 or even evisceration had been attempted, we opted for enucleation. Histopathologic examination of the ocular structures demonstrated a massive infiltration of the uveal tract and the optic nerve head with total destruction of the retinal structure. Thus, salvation of vision was not possible. These observations, along with the rapid and complete recovery of the child following the surgery, justify the radical approach of enucleation in similar cases.
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