Metastatic Serratia endophthalmitis associated with extravasation injury in a preterm neonate.

The authors report a case of a preterm neonate who presented with lid edema, corneal edema, and an inflammatory membrane with whitish exudates in the pupillary area, suggestive of endophthalmitis. There was also a cutaneous ulcer with an eschar on the right wrist at the site of extravasation associated with previous intravenous catheter. Cultures from the ulcer and vitreous samples both grew Serratia marcescens with identical antibiotic sensitivity and resistance patterns. The ocular infection was rapidly progressive and did not respond to administered medical and surgical therapy leading to subsequent phthisis bulbi. Serratia can cause endophthalmitis refractory to antibiotics and despite aggressive and timely treatment can have an unfavorable outcome. This report aims at highlighting the possibility of metastatic infection from an extravasation injury with a potentially fatal outcome.

Introduction

Neonatal endophthalmitis, although a rare occurrence, plays an important role in reviewing management strategies for neonatal care. Extravasation injury in the setting of an intensive care unit is known. The resultant necrotic skin has a potential for bacterial colonization with the possibility of metastatic infection. We report a case of metastatic endophthalmitis caused by Serratia marcescens in a preterm neonate. The nidus of infection was in the cutaneous ulcer caused by extravasation injury.

Case Report

A preterm neonate (30 weeks gestational age, birth weight of 1,600 grams) was sent to our institute for retinopathy of prematurity (ROP) screening, at post conceptional age of 33 weeks, following discharge from the neonatal intensive care unit (NICU) where he was being monitored. He had received supplementary oxygen, phototherapy, and routine antibiotic coverage. At the first visit, the neonate was diagnosed to have an avascular retina in zone 2 without plus disease in both eyes and was asked to follow-up after 2 weeks. However, the child was brought to the emergency department of our hospital 3 days later when the parents noticed periocular swelling and a white reflex in the left eye (OS). On examination, the child was afebrile. Eyelid and corneal edema with whitish exudates in the pupillary area were noted OS. Ultrasound B scan OS revealed the vitreous to be full of low to moderately reflective dot and clump echoes [Figure 1]. Right eye (OD) was status quo.

Figure 1

B-scan ultrasonogram of left eye at presentation, showing vitreous cavity with multiple moderate to high reflective dot and clump echoes

General examination, at this point, revealed a cutaneous ulcer with eschar on the dorsum of the right wrist at the site of a previous intravenous catheter [Figure 2a]. There was a history of intravenous drug extravasation at the site of the wrist ulcer, during the neonatal intensive-care unit (NICU) stay, following which local treatment had been administered. A provisional diagnosis of metastatic, endogenous endophthalmitis was made. The patient underwent a vitreous tap and broad spectrum intravitreal antibiotic (Vancomycin + Ceftazidime) injection as per hospital protocol.

Figure 2

(a) Clinical photograph at presentation of the right wrist showing the site of extravasation with eschar. (b) Right wrist with healed lesion after 2 weeks

The discharge from the skin lesions, vitreous aspirate, and blood samples were sent for microbiological evaluation. Cultures from the vitreous samples and skin lesions grew red mucoid colonies on blood agar and whitish mucoid colonies on chocolate agar. Staining revealed Gram-negative coccobacilli which were oxidase and indole negative. The organism was methyl red negative, Voges-Proskaeur, and citrate positive. Acid production from glucose, maltose, mannitol, and sucrose was positive, thereby suggestive of Serratia marcescens. Blood cultures were negative.

The antibiotic sensitivity and resistance patterns were identical in both the isolates. The isolates were sensitive to Cefotaxime, Gatifloxacin, Moxifloxacin, Ciprofloxacin, Levofloxacin, Piperacillin/tazobactam, Ceftazidime, and Amikacin. They showed resistance to Tetracycline, Cefuroxime, Cefazolin, and Vancomycin. The child underwent pars plana lensectomy with core vitrectomy and intravitreal Moxifloxacin. Post-operative systemic antibiotics (intravenous Cefotaxime 50mg/kg/day for 5 days) with topical antibiotics (Moxifloxacin 0.5% and Tobramycin 0.3% eye drops) two hourly for a week, then QID for a month and steroids (Prednisolone acetate 1% eye drops) two hourly with gradual taper, were continued. However the patient developed a retinal detachment [Figure 3] which was inoperable and the eye subsequently went into phthisis bulbi.

Figure 3

B-scan ultrasonogram of left eye 2 weeks post core vitrectomy showing closed funnel retinal detachment in a pre-phthisical eye

The fellow eye of the child progressed to zone 2 stage 3 ROP with plus disease for which he received laser photocoagulation. The skin ulcer was treated by debridement and topical antibiotic ointments and healed completely within a fortnight [Figure 2b]. At last follow-up, the 10-month-old baby was healthy and right eye was doing well following regression of ROP.

Discussion

Endogenous endophthalmitis is a disease that occurs due to spread of micro-organisms from a systemic nidus hematogenously across the blood retinal barrier to inoculate the intraocular tissues. A small inoculum can be sufficient to cause endophthalmitis but may not be detected in blood culture. In our case, the isolation of same organism with similar antibiotic sensitivity from two different sites points towards a metastatic infection.

The incidence of endophthalmitis in preterm neonates is on the decline globally.[1] Premature neonates with ROP are at an increased risk of endophthalmitis. Upregulation of vascular endothelial growth factor causes increased vascular permeability which promotes ocular seeding of organisms.[1] Most cases of endophthalmitis in neonates are due to pathogens transmitted perinatally and due to prolonged hospitalization.

Serratia marcescens is an aerobic, gram-negative coccobacillus of the Enterobacteriaceae family. Equi et al. have reported “dark hypopyon” in endogenous endophthalmitis caused by Serratia due to the production of a red pigment known as prodigiosin by the bacterium.[2] However, this clinical finding is not uniformly reported in all cases and cannot be considered as a diagnostic feature.

According to our literature search, there have been only four previously reported cases of neonatal endophthalmitis due to Serratia. Al Hazzaa et al. reported neonatal endogenous endophthalmitis due to Serratia following septicemia, presenting with a pink hypopyon.[3] This neonate was a full-term healthy baby and the source of infection was from an umbilical artery catheter. deCourten et al. reported a case of a neonate developing Serratia septicemia with endophthalmitis following colostomy for an imperforate anus. The endophthalmitis had a rapid downhill course and the eye had to be enucleated eventually.[4] The clinical characteristics of the other previously reported cases of neonatal endogenous endophthalmitis caused by Serratia marcescens are described in Table 1.

Table 1

Clinical features of reported cases of neonatal endophthalmitis caused by Serratia marcescens

The incidence of nosocomial infection due to Serratia is more common with debilitated, immune-compromised individuals and those with indwelling catheters or intravenous lines. The organism shows multiple drug resistance, due to altered call wall preventing drug entry, inactivating enzymes and β-lactamases.[7] Tan et al. reported a similar case of metastatic Serratia endophthalmitis in a diabetic adult, following phlebitis at site of intravenous catheter. The infection which started in the cilliary body was progressive despite treatment and the eye was eventually eviscerated.[8]

Extravasation injury can occur frequently in the setting of an intensive care unit. Neonates are especially susceptible as the skin and subcutaneous tissue is thin and poorly supported. Extravasation is reported to occur in up to 70% neonates in an NICU setting who are dependent on peripheral infusion lines.[9] Various therapeutic agents containing calcium, potassium, bicarbonates, dextrose, and antibiotic agents have been implicated as causative for extravasation injury. The degree of extravasation damage depends on the site, chemical characteristics of the agent administered, the duration of soft tissue exposure, and the patient's general health.[1011] The management of extravasation injuries should be prompt and effective. These include measures like removal of the extravasated agents, application of local antibiotics, application of hot or cold packs, local application of hyaluronidase, and surgical debridement whenever needed.

Care of a preterm neonate is fraught with many hurdles. Prolonged parenteral support is needed, with risk of occurrence of extravasation injury. To the best of our knowledge, this is the first reported case of metastatic endophthalmitis in a preterm neonate from a nidus following extravasation injury from an intravenous catheter. We present this case to highlight this potential risk, emphasizing the need for prompt care of extravasation injury to prevent such a dreaded outcome.