**22. Endogenous endophthalmitis: presenting features and diagnosis**

New onset of floaters, blurred vision, photophobia and ocular discomfort in a patient with underlying systemic risk factors may be the presenting features of endogenous endophthal‐ mitis. Clinical findings in endogenous endophthalmitis may include decreased VA, ocular pain, conjunctival injection, hypopyon, corneal edema, vitritis and reduced fundus view (Figure 16). Endogenous bacterial endophthalmitis is bilateral in approximately 14- 25% of cases. In bilateral infection, simultaneous ocular involvement is the rule; however, one eye is characteristically more severely affected than the other eye. Delayed involvement of the sec‐ ond eye can occur even in patients already being treated with systemic antibiotics. The right eye is involved twice as often as the left, probably because of this eye's proximity and more direct blood flow from the right carotid artery. There is no gender predisposition in cases of endogenous endophthalmitis. For prognostic purposes, endogenous endophthalmitis has been classified based on location (anterior or posterior) and extent (focal or diffuse). [72] Ac‐ cording to this classification, focal and anterior cases appear to have a good prognosis, while posterior and diffuse endophthalmitis nearly always leads to blindness. In panophthalmitis, severe involvement of both the anterior and posterior segment is associated with inflamma‐ tion of orbital structures, indicated by marked eyelid edema, chemosis, proptosis and limita‐ tion of eye movements. Ultrasonography may be helpful in the diagnosis; the combination of thickening of the retinochoroid layer and echoes in the vitreous supports the diagnosis of endophthalmitis. [72, 84] On MRI of the orbits, intra-ocular hyperintensity on fluid-attenuat‐ ed inversion recovery and diffusion-weighted images have been found to be very useful for diagnosing endophthalmitis. [85] No eyes that have suffered posterior, diffuse or panoph‐ thalmitis has received any useful vision regardless of management. [7] Pathological exami‐ nation of the enucleated globes in panophthalmitis has revealed that most of the retina is necrotic resulting in devastating visual outcome. [72]

year period, 86 cases were reported; 10 of these were due to endogenous causes. [71] The poor visual outcome in these patients has been related to the delay in the early diagnosis and ap‐ propriate timely treatment. [72] Systemic symptoms rather than acute ocular symptoms may be the most common reasons for a patient to present to a physician and many of these cases may be initially misdiagnosed. Jackson et al. reviewed 267 reported cases of endogenous bac‐

The most frequent risk factors for developing endogenous endophthalmitis include a prior history of diabetes mellitus, gastrointestinal disorders, hypertension, heart valve diseases, endocarditis, chronic obstructive lung disease, previous wound infection, meningitis, urina‐ ry tract infection, cystic fibrosis, immune-compromised status, splenectomy, organ trans‐ plantation and indwelling intravenous catheters, hepatic abscess, hemodialysis fistula, peritonitis and intravenous drug abuse (Figure 15). [71-78] Less frequent risk factors include, otitis media, dental infection, septic arthritis, abortion, pharyngitis and Hemoglobin SC dis‐ ease. [79-83] Other chronic diseases such as immunosuppressive status, HIV infection, can‐ cer, renal failure requiring dialysis, long-term use of broad-spectrum antibiotics, use of steroids and other immunosuppressive drugs, intravenous hyper-alimentation and indwel‐ ling intravenous catheters can lead potential pathogens access to the circulatory system and septicemia. History of chronic intravenous drug abuse, dental work, otitis media, soft-tissue infection including orbital cellulitis, and septic arthritis may lead to septicemia and endoge‐

(a) (b) (c)

**Figure 15.** External photograph of a diabetic patient who presented with loss of vision and painful ophthalmoplegia of his right eye along with fever and mental status changes (a). He was found to have severe panophthlamia of his right eye and ultrasonography revealed endophthalmitis (b). Computed tomography (coronal view) of his brain re‐ vealed evidence of septic emboli (c). Patient was treated with systemic antibiotics and right eye evisceration.

New onset of floaters, blurred vision, photophobia and ocular discomfort in a patient with underlying systemic risk factors may be the presenting features of endogenous endophthal‐ mitis. Clinical findings in endogenous endophthalmitis may include decreased VA, ocular

**22. Endogenous endophthalmitis: presenting features and diagnosis**

terial endophthalmitis and also presented a 17-year prospective series. [67]

**21. Risk factors for endogenous endophthalmitis**

nous endophthalmitis. [3, 79, 80]

194 Common Eye Infections

**Figure 16.** External photograph of a patient's eye who presented with pain, conjunctival chemosis and decreased vi‐ sion. His examination was significant for having an evidence of anterior chamber reaction in the form of hypopyon and vitritis. A diagnosis of endogenous endophthalmitis was made in the absence of patient's having no prior history of ocular trauma or surgery.

The majority of patients with endogenous endophthalmitis are initially misdiagnosed and many have an underlying systemic diseases frequently overlooked by ophthalmologists (Figure 17). Blood cultures may be the most frequent means for establishing the infective cause. If not diagnosed early on and therapy initiated, endogenous bacterial endophthalmi‐ tis usually leads to total loss of vision. [7] In Candida infections, localized fluffy creamy white retinal or sub-retinal nodules may be associated with vitreous haze. [82, 83] In ad‐ vanced cases of fungal endogenous endophthalmitis, one may encounter areas of peri-vas‐ cular infiltrates, retinal infarction, hemorrhages and retinal necrosis. Patients having evidence of systemic fungal infection need to be screened for any peripherally located fun‐ gal lesions as these patients may be asymptomatic initially.

**Figure 17.** External photograph of a child who presented with gradual swelling of his right eyelids, pain and loss of vision over one month period after a bout of gastrointestinal illness. There was no prior history of eye trauma or sur‐ gery (a). Based on ultrasonography (b), a diagnosis of panophthalmitis was made and the child was treated with intravitreal antibiotic injection after obtaining vitreous biopsy to which patient responded well. Culture results revealed evidence of Enterococcus faecalis and the eye became rapidly phthisical (c).

Early diagnosis of endogenous endophthalmitis can be suspected only if there are ocular symptoms associated with concomitant systemic infection. [86] While in adults, early ocular symptoms may prompt patients to see an ophthalmologist and perhaps endogenous en‐ dophthalmitis diagnosed and treated early in the course, in cases of pediatric endogenous endophthalmitis delay in early diagnosis and treatment may result in no light perception vi‐ sion or loss of an eye. [7, 87] The earliest symptoms of adult endogenous endophthalmitis include pain and decreased vision. However, because of poor communication in pediatric patients diagnosing endogenous endophthalmitis at an early stage is very difficult. Unfortu‐ nately, in pediatric patients endogenous endophthalmitis is often not suspected and may be even misdiagnosed as uveitis, persistent hyperplastic primary vitreous, cataract, retinopathy of prematurity, Toxocariasis, Coat's disease, retinal detachment and retinoblastoma. [7, 72]

Patients suspected of having endogenous endophthalmitis require immediate investigation with blood cultures along with anterior chamber and vitreous taps and possibly vitrectomy along with intravitreal antibiotic injections. [88] Gram stain of the specimens along with cul‐ tures and sensitivity as well as PCR if possible should be performed. Isolation of any bacteri‐ al colonies on direct inoculation of agar plates cultured aerobically or anaerobically may be indicative of culture-positive endophthalmitis. Blood cultures may be the most frequent means for establishing the infective cause. Identification of the causative pathogen by blood, urine, or cerebrospinal fluid culture may be successful in over 75% of endogenous endoph‐ thalmitis cases. Positive cultures from vitreous samples can be achieved much less frequent‐ ly in endogenous endophthalmitis than in exogenous endophthalmitis. [3, 67, 71, 72] Vitrectomy has the advantage of obtaining material for cytologic and microbiologic studies to make the correct diagnosis and allowing removal of the offending organisms. Vitreous specimens for culture obtained by vitrectomy have been found to be more sensitive in de‐ tecting the causative organism than the vitreous needle biopsy. [88, 89] In some cases, the culture of the vitreous samples may not grow any bacteria probably due to effect of antibiot‐ ics. Vitreous biopsy should be considered because a culture of the vitreous sample is useful for identifying the responsible bacteria. The positive rate for identification of any causative organism may be 87% for vitreous, 32% for aqueous humor, and 33% for blood. In addition to cultures, in certain cases and for fastidious organisms, bacterial and fungal DNA can be detected by PCR assay in specimens obtained from the ocular tissues. [90 -92] DNA extract‐ ed using a single-extraction protocol from 50 microL of vitreous and amplified with broadrange bacterial and fungal primers (targeting the conserved 16S and 18S ribosomal RNA gene sequences of bacteria and fungi, respectively) may enable the rapid differentiation be‐ tween bacterial and fungal endophthalmitis and allow tailoring of therapy to individual pa‐ tients. [91, 93] RNA-based Reverse Transcriptase PCR (RT-PCR) can be utilized to confirm presence of viable bacteria in intraocular specimens obtained from patients with infectious endophthalmitis. RT-PCR can serve as a rapid and reliable tool to detect viable bacteria causing endophthalmitis. [20]

#### **23. Bacteriology of endogenous endophthalmitis**

tis usually leads to total loss of vision. [7] In Candida infections, localized fluffy creamy white retinal or sub-retinal nodules may be associated with vitreous haze. [82, 83] In ad‐ vanced cases of fungal endogenous endophthalmitis, one may encounter areas of peri-vas‐ cular infiltrates, retinal infarction, hemorrhages and retinal necrosis. Patients having evidence of systemic fungal infection need to be screened for any peripherally located fun‐

(a) (b) (c)

**Figure 17.** External photograph of a child who presented with gradual swelling of his right eyelids, pain and loss of vision over one month period after a bout of gastrointestinal illness. There was no prior history of eye trauma or sur‐ gery (a). Based on ultrasonography (b), a diagnosis of panophthalmitis was made and the child was treated with intravitreal antibiotic injection after obtaining vitreous biopsy to which patient responded well. Culture results revealed

Early diagnosis of endogenous endophthalmitis can be suspected only if there are ocular symptoms associated with concomitant systemic infection. [86] While in adults, early ocular symptoms may prompt patients to see an ophthalmologist and perhaps endogenous en‐ dophthalmitis diagnosed and treated early in the course, in cases of pediatric endogenous endophthalmitis delay in early diagnosis and treatment may result in no light perception vi‐ sion or loss of an eye. [7, 87] The earliest symptoms of adult endogenous endophthalmitis include pain and decreased vision. However, because of poor communication in pediatric patients diagnosing endogenous endophthalmitis at an early stage is very difficult. Unfortu‐ nately, in pediatric patients endogenous endophthalmitis is often not suspected and may be even misdiagnosed as uveitis, persistent hyperplastic primary vitreous, cataract, retinopathy of prematurity, Toxocariasis, Coat's disease, retinal detachment and retinoblastoma. [7, 72]

Patients suspected of having endogenous endophthalmitis require immediate investigation with blood cultures along with anterior chamber and vitreous taps and possibly vitrectomy along with intravitreal antibiotic injections. [88] Gram stain of the specimens along with cul‐ tures and sensitivity as well as PCR if possible should be performed. Isolation of any bacteri‐ al colonies on direct inoculation of agar plates cultured aerobically or anaerobically may be indicative of culture-positive endophthalmitis. Blood cultures may be the most frequent means for establishing the infective cause. Identification of the causative pathogen by blood, urine, or cerebrospinal fluid culture may be successful in over 75% of endogenous endoph‐ thalmitis cases. Positive cultures from vitreous samples can be achieved much less frequent‐ ly in endogenous endophthalmitis than in exogenous endophthalmitis. [3, 67, 71, 72] Vitrectomy has the advantage of obtaining material for cytologic and microbiologic studies

gal lesions as these patients may be asymptomatic initially.

196 Common Eye Infections

evidence of Enterococcus faecalis and the eye became rapidly phthisical (c).

Depending on location, a wide range of organisms have been shown to cause endogenous endophthalmitis. Causative organisms of endogenous endophthalmitis may be bacteria, as well as fungi, which vary depending on the geographical location. For example in Europe and the United States, Streptococcus species, Staphylococcus aureus, and other Gram-posi‐ tive bacteria account for two-thirds of bacterial endogenous endophthalmitis cases and Gram negative isolates are found in only 32% of cases. [71, 82] These numbers differ signifi‐ cantly from East Asia, where most cases of endogenous endophthalmitis are caused by Gram-negative organisms especially Klebsiella species accounting for 80% to 90% of positive cultures. [67, 94] The difference might be associated with higher incidence of cholangio-hep‐ atitis and liver abscess in these patients. Some of the other reported organisms include, Can‐ dida albicans, Neisseria meningitis, Enterococcus, Haemophilus influenzae, Klebsiella, Salmonella, Streptococcus, Staphylococcus aureus, Escherichia coli, Kingella Kingae, Pseu‐ domonas aeroginosa, Propionibacterium acnes, Serratia, Bacillus cereus, Brucella melitensis and Actinobacillus. [67, 71-73, 77, 78, 81, 84, 95-98] Studies from East Asian countries have reported liver abscess as the major source of infection and Klebsiella pneumoniae as the causative organism. [81, 94] Incidence of fungal endogenous endophthalmitis has increased in recent years, Candida albicans and Aspergillus species being the prominent causative agents. Candida species are the most common cause of nosocomial fungal infections in com‐ promised hosts. Candida chorioretinitis occur predominantly as a result of candidemia seeding the eye. Cryptococcus and Fusarium species have also been reported to the cause of endogenous fungal endophthalmitis. Compared with published series of post-operative or post-traumatic endophthalmitis, patients with endogenous endophthalmitis are more likely to have fungal isolates with a predominance of Candida albicans. The most common Gram positive organisms are Staphylococcus aureus, group B streptococci, Streptococcus pneumo‐ niae,and Listeria monocytogenes; the most common Gram negative organisms are Klebsiella spp., Escherichia coli, Salmonella, Pseudomonas aeruginosa, and Neisseria meningitidis. [2, 3, 69, 91]

#### **24. Management of endogenous endophthalmitis**

The optimal treatment for endogenous endophthalmitis is controversial. When indicated, these patients may require systemic antibiotics in addition to the PPV. While EVS has provid‐ ed guidelines for the role of early vitrectomy and intra-vitreal antibiotics in post-operative en‐ dophthalmitis, no such study has addressed endogenous endophthalmitis. Data from the EVS may not be applicable to cases of endogenous endophthalmitis because the spectrum of caus‐ ative organisms differs significantly in endogenous endophthalmitis as compared to post-op‐ erative endophthalmitis. Although systemic and intra-vitreal antibiotics may be sufficient in milder forms of infection, PPV has been shown to be helpful in severe cases of endogenous en‐ dophthalmitis. More virulent organisms such as endotoxin-producing Streptococcus and Ba‐ cillus species are commonly involved in endogenous endopthalmitis. [67, 71] In addition, material from vitrectomy may provide a better source for culture. This is particularly true in children because of the variety of pediatric cases and lack of sufficient experience in diagnos‐ ing in this age group. [7] In the adults, early intervention with PPV has been found to be high‐ ly effective, no such data has been proven for cases of pediatric endogenous endophthalmitis. Suggested medical treatment in these patients include topical, sub-conjunctival and intra-vi‐ treal injection of antibiotics having broad coverage with consideration for corticosteroids in cases of severe inflammation. Patients with endogenous endophthalmitis should be evaluat‐ ed for underlying systemic conditions. Systemic anti-microbial therapy is the mainstay of en‐ dogenous endophthalmitis. Intravitreal antibiotic selection is similar to exogenous endophthalmitis including Vancomycin (1.0 mg/0.1 mL) for Gram-positive coverage or in combination with Ceftazidime (2.25 mg/0.1 mL) or Amikacin (400 ug/0.1 mL) for Gram-nega‐ tive coverage.. In general, systemic therapy must be continued for several weeks to ensure eradication of the infection. Generally, a combination of intra-vitreal antibiotics is injected that may include Vancomycin, Cephazolin or Ceftazidime and Amikacin after the tap has been performed. Systemic antibiotics are administered according to the focus of the infection. Infec‐ tious diseases consultation may be sought in cases of endocarditis and early vitrectomy should be planned if indicated. [88] Immediate vitrectomy is performed in eyes with lightperception-only vision at the initial visit. Routine immediate vitrectomy is not necessary in eyes presenting with better than light-perception vision. Aggressive therapy and early vitrec‐ tomy may be considered in endogenous endophthalmitis caused by virulent pathogens such Pseudomonas aeruginosa and in cases of Klebsiella endophthalmitis. [81, 97, 99] Patients with endogenous endophthalmitis who undergo PPV early in the course of endogenous endoph‐ thalmitis may end up with some useful vision.
