Secondary Logo

Journal Logo

Original Article

Stenotrophomonas maltophilia

An emerging entity for cluster endophthalmitis

Beri, Sarita; Shandil, Anurag; Garg, Rajiv

Author Information
doi: 10.4103/ijo.IJO_314_17
  • Open


Intravitreal injections are the preferred method of administering drugs for the posterior segment pathologies of eye. It is an invasive procedure and was first described by Rycroft in 1945 when he gave intravitreal injection of penicillin for the treatment of endophthalmitis.[1]

Bevacizumab (AVASTIN®, Genentech, Inc.,) is a 149 kDa full-length humanized monoclonal immunoglobulin G antibody against vascular endothelial growth factor-A (VEGF-A) with a half-life of 9.8 days in human vitreous. It was the first drug therapy approved by the US Food and Drug Administration which could be used to inhibit angiogenesis in tumors such as colorectal cancer.[2] In 2005, Rosenfeld et al. first described the use of intravitreal bevacizumab (IVB) for the treatment of macular edema secondary to retinal vein occlusion and exudative age-related macular degeneration (ARMD).[3] The very high cost of other anti-VEGF drugs such as pegaptanib and ranibizumab led to the use of cost-effective bevacizumab in an “off-label” capacity by clinicians worldwide.

Stenotrophomonas (Xanthomonas) maltophilia is an aerobic, nonfermentative, Gram-negative bacillus found in various aquatic environments. It is associated with wet surfaces and can form biofilms in potable water distribution systems. Cells of S. maltophilia have the ability to survive with minimal nutrients, for example, in drinking water, treated water (after water treatment of filtration, reverse osmosis, ultraviolet exposure, or deionization), and dialysate effluent.[4] It is a noninvasive, low virulence organism, and frequently colonizes fluids used in a hospital setting (e.g., irrigation solutions, intravenous fluids) and patient secretions (e.g., respiratory secretions, urine, wound exudates). It is usually not capable of causing disease in a healthy host without the assistance of invasive medical devices that bypass normal host defenses.[5]

The first reported case of S. maltophilia endophthalmitis was in 1989 after implantation of an intravitreal ganciclovir implant in a patient with acquired immune deficiency syndrome.[6] The risk of cluster endophthalmitis after IVB is high as multiple injections are given from the same vial which is stored at low temperature, or multiple patients may receive injections from the same vial in a single session. The vial sterility is at stake either due to manufacturing protocols, improper storage of drug, or lapse in cold chain. There is no current consensus on the preferred treatment of postinjection endophthalmitis and most clinicians follow the recommendations of endophthalmitis vitrectomy study.

In various clinical trials of anti-VEGF treatment, the reported incidence rate of bacterial endophthalmitis varies between 0.05% and 0.2% per injection, while the incidence of sterile endophthalmitis has been described between 0.09% and 1.1% of IVB injections.[789] Here, we report the occurrence of endophthalmitis in 10 eyes of 10 patients, after intravitreal injection of bevacizumab from the same vial in a single sitting.


This study presents a review of 10 eyes of 10 patients who were administered IVB (Avastin®) injection in November 2015 for various posterior segment diseases. It was later approved by the institutional review board.

The mean age of the patients was 55.5 years (range: 45–72). There were five females and five males, six affected in the right eye and four in the left. The details of the procedure and possible complications related to intravitreal injection of bevacizumab were explained to each patient. All patients signed the informed consent forms, in which the use of an off-label drug was also explained. All patients were called in the morning to the operation theater on the same day after preparation with topical antibiotics for 3 days and proper diabetic control. The vial of injection bevacizumab (100 mg/4 ml) came through hospital purchase and was refrigerated at 4°C. The vial was opened on the day of injection in the operation theater, which was maintained with laminar air flow, under full aseptic precautions. The contents of the vial were withdrawn into a 2-ml syringe and then 0.05 ml was transferred into ten, 30 gauge 1 ml tuberculin syringes and each kept on a separate sterile tray. Before the procedure, the operating surgeons scrubbed their hands thoroughly and wore sterile gowns and gloves. Gloves were changed after each injection. The eye of every patient was prepared using standard aseptic procedures. Lids were cleaned with 10% povidone-iodine. An ophthalmic drape and sterile lid speculum were used in each case. Freshly opened 0.5% proparacaine hydrochloride drops were instilled 4–5 times for topical anesthesia. Drops of 5% povidone-iodine were instilled 4–5 times preinjection.

IVB injection (1.25 mg in 0.05 ml) was administered into the vitreous cavity through the inferotemporal quadrant 3.5–4 mm from the limbus by 30-gauge needle attached to a tuberculin syringe. As the needle was withdrawn, a sterile cotton tip was applied for local pressure over the entry site for a few seconds to avoid reflux. Immediately after injection, 5% povidone-iodine solution was applied to the ocular surface. Following injection, the patient's intraocular pressure was checked digitally and fundus was checked to ensure the retinal artery was well perfused. Eye was patched and patient sent home. Oral diamox was administered for 1 day and oral ciprofloxacin was started for 5 days. Topical antibiotic tobramycin and timolol were also prescribed.


All patients came the next morning for routine follow-up in the outpatient department. They all presented with marked diminution of vision, mild pain, redness, vitreous reaction, and hypopyon. All the patients were thoroughly examined using slit-lamp biomicroscopy (SLE), indirect ophthalmoscopy, and B-scan ultrasonography. Patient's clinical symptoms, Snellen visual acuities, and aqueous and vitreous inflammation were graded.

On SLE, all patients had ciliary congestion, cells 3+, flare 2+, 1–2 mm mobile hypopyon. Remarkably, pupillary synechiae were absent. Vitreous exudates were present on B-scan ultrasonography, and fundal glow was present on indirect ophthalmoscopy, but details were not visible in any patient.

All the patients were clinically diagnosed to have postinjection endophthalmitis. They were immediately started on 0.5% moxifloxacin eye drops administered half hourly, and homide eye drops till they were taken up for intravitreal therapy. After taking full aseptic precautions and patient preparation, a vitreous tap along with intravitreal antibiotics and steroid injections was carried out. Vitreous tap was done using a 2-ml syringe and a 26-gauge needle. A minimum of 0.05 ml of vitreous sample was obtained. With a second 1-ml syringe with a 30-gauge needle anterior chamber sample of approximately 0.05 ml was obtained. A small drop of vitreous sample was put onto a glass slide for Gram staining and in another slide for KOH mount, covered by a cover slip. Blood, chocolate, MacConkey, and Sabouraud dextrose agar plates were inoculated and sent to the microbiology laboratory. The same procedure was done for the aqueous sample as well.

Intravitreal injection of vancomycin 1 mg in 0.1 ml, ceftazidime 2.25 mg in 0.1 ml, and dexamethasone 0.4 mg in 0.1 ml were injected. Topical fortified antibiotics (vancomycin 5% and ceftazidime 5%) and cycloplegics (eye ointment atropine sulphate 1%) were started. Intravenous systemic broad-spectrum antibiotics (Augmentin and Amikacin) and oral ciprofloxacin 750 mg BD were also started on the same day. Subconjunctival dexamethasone (0.5 ml) and gentamycin (0.5 ml) BD were also given for 3 days. Patients’ blood sugar, kidney function, and liver function tests were also monitored.

There was minimal improvement in all patients the following day. Keeping in mind the early presentation, a presumptive diagnosis of Gram-negative bacillus infective endophthalmitis was made. Intravenous antibiotics were changed to linezolid 600 mg BD and ceftazidime 1 g BD. Oral and topical steroids to reduce the inflammation were also added.

Two patients (2/10) with poor diabetic control deteriorated further and underwent pars plana vitrectomy (PPV) within 48 h. A repeat of the same intravitreal antibiotics and steroids was given to (8/10) patients after 48 h. Three patients showed marked improvement after the second intravitreal, while the other five patients showed a slow response to treatment.

Gram staining showed pus cells in vitreous specimens of five patients, and two cases were culture-positive (20%). Pseudomonoid species was reported in one case and in the other Providencia alcalifaciens was cultured, which is also a Gram-negative pseudomonoid. Antibiotic susceptibility testing showed the organisms to be sensitive to ceftazidime, levofloxacin, imipenem, and resistant toward meropenem, amoxicillin-clavulanic acid, clindamycin, and piperacillin-tazobactam.

The vial from the same batch was cultured at our microbiology laboratory and showed Gram-negative bacilli S. maltophilia using VITEK™ (automated bacteriological identification system). The organism was found to be sensitive to clindamycin, ceftazidime, cefta-clavulinic acid, and resistant toward meropenem, imipenem, amoxicillin-clavulinic acid, and piperacillin-tazobactam, similar to the reported pseudomonoid bacilli.

By the 6th day, all patients had started showing signs of improvement. However, many patients had epithelial toxicity due to topical medications. Topical vancomycin 5% was stopped and ceftazidime 5% was continued.

All patients were discharged by the 10th day on oral levofloxacin 750 mg, topical antibiotics, cycloplegics, and topical steroids. They were advised to regularly follow-up in the outpatient department.

Visual acuity returned to near preendophthalmitis levels in 9/10 eyes after 1 month. One patient with diabetes who underwent PPV was lost to follow-up (patient no. 5). However, by the end of 2 months, vision of all patients had started deteriorating. One patient with ARMD had retinal detachment which was operated with satisfactory results (patient no. 10). Another patient with central retinal venous occlusion and very poor visual prognosis was advised injection lucentis which he could not afford and went into neovascular glaucoma (patient no. 9). The rest (7/10) were given repeat intravitreal lucentis in the following 12 months and fared well. The mean follow-up period ranged from 6 to 12 months [Table 1].

Table 1
Table 1:
Indication for Avastin therapy and best-corrected visual acuity of patients before intravitreal Avastin injection, best-corrected visual acuity of patients on presentation of endophthalmitis postintravitreal Avastin injection, on subsequent treatment with complications and follow-up

After noting endophthalmitis, sterilization procedures in the hospital were reviewed. To determine the origin of the infection, multiple surveillance samples were collected from the operation theater air, disinfectants, the povidone-iodine solutions, paracaine, irrigation solutions, syringes and needles, buds, cidex, gauze, and tubes and various instruments. The culture media were incubated for 3 days and were reported to be negative.


The incidence of endophthalmitis has risen markedly with the increased use of intravitreal injections in recent times. Multiple large series and population-based studies have reported the per-injection endophthalmitis risk to be 0.03% or less.[10111213141516] The prospective CATT study has reported endophthalmitis rates of 0.7% with ranibizumab and 1.2% with bevacizumab.[17] The prospective randomized controlled trial of alternative treatments to inhibit VEGF in age-related choroidal neovascularization reported “severe uveitis” in one of 610 patients in 1 year (0.16%), but it did not specifically report endophthalmitis.[18]

McCannell and Moshfeghi et al. recently reported eight of 26 (30.8%) and five of seven (71.4%) culture-positive postinjection endophthlamitis cases, respectively, due to streptococcal isolates.[13] Artunay et al. have reported two cases of acute culture-positive endophthalmitis per 3022 eyes. Staphylococcus epidermidis and haemophilus influenzae were isolated and made the incidence of acute culture-positive endophthalmitis 0.066%.[9]

In our report, only two out of ten were culture proven and pseudomonoid species was cultured in both cases. The vial of the same batch was cultured and showed the presence of S. maltophilia using VITEK™. Normal culture and identification methods are unable to identify S. maltophilia and report it as contaminants or pseudomonoid species. The VITEK™ system gives fast, accurate microbial identification, and antibiotic susceptibility testing. It provides greater automation while increasing safety and eliminating repetitive manual operations and is superior to manual microbial identification techniques.

It is recommended now that the undiluted vitreous and aqueous samples are directly instilled in thioglycollate broth, which is a multipurpose, enriched media, and has the nutrients to support bacterial growth. One drop of the collected sample should also be placed on a glass slide and air-dried before transport for Gram staining. The thioglycollate broth is then centrifuged and the organism-rich supernatant is then plated to get pure colonies without contamination. These colonies can then be identified using VITEK™ or through manual methods.

Horster et al. reported an outbreak of S. maltophilia endophthalmitis in a series of 26 patients following cataract surgery.[19] In this series, all patients had surgery within 2 days at the same hospital. The irrigation solution was found to be the source of the pathogen. Chang et al. and Williams et al. reported cases of S. maltophilia endophthalmitis after uneventful cataract surgery with intraocular lens implantation. It was related to surgical equipment contamination.[2021] In 2015, Ji et al. reported 14 cases of S. maltophilia endophthalmitis in a span of 5 months. The organism was found in cultures of aspiration fluids from phacoemulsification as autoclavable cassettes were used.[22] In our report, the contaminated solution in the vial and the direct injection of the contaminated fluid into the vitreous resulted in quicker and more pronounced inflammation.

S. maltophilia is a multidrug resistance organism due to low-membrane permeability, chromosomally encoded multidrug resistance pumps, plasmids harboring antibiotic resistance genes, and various gene transfer mechanisms involved in the acquisition of antimicrobial resistance. It exhibits intrinsic resistance to a broad range of currently used antibiotics and therefore constitutes a special clinical challenge. It can also develop resistance to a drug to which it was previously sensitive and antimicrobial resistance may emerge during therapy.[4] Our patients responded well after initial topical, systemic and intravitreal ceftazidime injection and the pathogen was sensitive to this drug.

Chen et al. and Penland and Wilhelmus reported endophthalmitis with S. maltophilia which were resistant to ceftazidime.[2324] Williams et al. reported that two of the three cases of S. maltophilia endophthalmitis isolated from culture were resistant to ceftazidime but sensitive to amikacin and ciprofloxacin.[21] In 2015, Ji et al. reported resistance to antibiotics such as amikacin, ceftazidime, SMZ/TMP, and ciprofloxacin with sensitivity to levofloxacin.[22] However, recent reports such as those from Chang et al. reported sensitivity to ceftazidime, amikacin, polymyxin b, TMP-SMX, ciprofloxacin, and levofloxacin.[20]

The reason for this difference could be due to selective preference of antibiotic use in differing geographic regions or different time periods of study. Furthermore, the methodology, resistance criteria, and media used for antibiotic sensitivities may have differed in these studies. S. maltophilia infections can be difficult to treat because of contradictory findings between in vitro and in vivo antibiotic susceptibility studies. Ceftazidime is often a first-line intravitreal antibiotic agent, chosen because of its wide coverage, and low-intraocular toxicity. Another common first-line option is amikacin. Both drugs produced the described effects in our cases. In our case, the organism was resistant to meropenem, imipenem, amoxicillin-clavulanic acid, and piperacillin-tazobactam.

In our report, endophthalmitis induced by S. maltophilia had clinical characteristics similar to those reported by Ji et al.[22] Corneal edema was present, but pupil synechia was not seen in these patients at any stage of inflammation. Fibrinolysin, one of the extracellular enzymes of S. maltophilia, is said to play a role in inhibiting the process of fibrin membrane and synechiae formation.

Endophthalmitis typically presents after an incubation gap. Only fulminant infections present so early. In our study, the quick presentation was due to the contents of the contaminated vial being directly injected into the vitreous through intravitreal injection. Vitreous is known to be a very good medium for bacterial growth.

The salient features of our report are that endophthalmitis presented within 24 h and treatment started immediately. Intravitreals were given within 3 h of diagnosis. Ceftazidime was used intravitreally, systemically, and topically, to which the organism was later found to be sensitive. Only two patients needed PPV and no patients needed evisceration or enucleation. It is recommended that all patients undergoing intravitreal injections should be followed up the next day. The greatest potential for improvement of outcome lies in early detection and reduction of the time interval between diagnosis and treatment. VITEK™ should be done for all vitreous aspirates for prompt diagnosis.

In our review, all ten patients had signs and symptoms of endophthalmitis, and classically pupillary synechiae were absent at any point. It is possible that this absence could be pathognomonic toward S. maltophilia infection. The quick presentation pointed toward Gram-negative infection, but the absence of chemosis, pain, and corneal infiltrate was atypical of a Gram-negative bacteria. S. maltophilia is a pseudomonoid whose growth from the injection vial was identified using VITEK™. The manual identification system also revealed pseudomonoid growth from the intravitreal tap thus pointing towards vial contamination. The antibiotic susceptibility profile of both samples is also similar; therefore, the possibility of drug contamination cannot be ruled out.

Many such reports of cluster endophthalmitis due to S. maltophilia infection after IVB injection in various parts of the country were published in newspapers from December 2015 to January 2016. The Drug Controller General India (DCGI) banned the drug Avastin for intravitreal use in January 2016. Later, DCGI reversed the ban after various deliberations with retinal surgeons all over India on March 2016, and recommendations were published for the safe and effective use of bevacizumab injection for ophthalmic purpose.[25]


The overall number of patients with endophthalmitis following intravitreal injections has risen dramatically over the past few years. The present report emphasizes the microbial contamination of the drug vial. The message is to stay vigilant and next day follow-up of all patients undergoing intravitreal injections is a must. S. maltophilia should be considered a pathogenic organism of postintravitreal endophthalmitis, especially if pupillary synechiae are absent on clinical examination. Its resistance to many drugs commonly used against Gram-negative bacilli and ability to develop resistance during treatment makes it difficult to manage the infection. Early detection with prompt management would improve the visual outcome for these patients. VITEK™ is to be used for early and accurate diagnosis of pathogens.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

1. Rycroft BW. Penicillin and the control of deep intra-ocular infection Br J Ophthalmol. 1945;29:57–87
2. Spaide RF, Laud K, Fine HF, Klancnik JM Jr, Meyerle CB, Yannuzzi LA, et al Intravitreal bevacizumab treatment of choroidal neovascularization secondary to age-related macular degeneration Retina. 2006;26:383–90
3. Rosenfeld PJ, Fung AE, Puliafito CA. Optical coherence tomography findings after an intravitreal injection of bevacizumab (avastin) for macular edema from central retinal vein occlusion Ophthalmic Surg Lasers Imaging. 2005;36:336–9
4. Denton M, Kerr KG. Microbiological and clinical aspects of infection associated with Stenotrophomonas maltophilia Clin Microbiol Rev. 1998;11:57–80
5. Araoka H, Baba M, Yoneyama A. Risk factors for mortality among patients with Stenotrophomonas maltophilia bacteremia in Tokyo, Japan, 1996-2009 Eur J Clin Microbiol Infect Dis. 2010;29:605–8
6. Chen S, Stroh EM, Wald K, Jalkh A. Xanthomonas maltophilia endophthalmitis after implantation of sustained-release ganciclovir Am J Ophthalmol. 1992;114:772–3
7. Wu L, Martínez-Castellanos MA, Quiroz-Mercado H, Arevalo JF, Berrocal MH, Farah ME, et al Twelve-month safety of intravitreal injections of bevacizumab (Avastin): Results of the Pan-American Collaborative Retina Study Group (PACORES) Graefes Arch Clin Exp Ophthalmol. 2008;246:81–7
8. Fintak DR, Shah GK, Blinder KJ, Regillo CD, Pollack J, Heier JS, et al Incidence of endophthalmitis related to intravitreal injection of bevacizumab and ranibizumab Retina. 2008;28:1395–9
9. Artunay O, Yuzbasioglu E, Rasier R, Sengül A, Bahcecioglu H. Incidence and management of acute endophthalmitis after intravitreal bevacizumab (Avastin) injection Eye (Lond). 2009;23:2187–93
10. Rasmussen A, Bloch SB, Fuchs J, Hansen LH, Larsen M, Lacour M, et al A 4-year longitudinal study of 555 patients treated with ranibizumab for neovascular age-related macular degeneration Ophthalmology. 2013;120:2630–6
11. Gillies MC, Walton R, Simpson JM, Arnold JJ, Guymer RH, McAllister IL, et al Prospective audit of exudative age-related macular degeneration: 12-month outcomes in treatment-naive eyes Invest Ophthalmol Vis Sci. 2013;54:5754–60
12. Englander M, Chen TC, Paschalis EI, Miller JW, Kim IK. Intravitreal injections at the Massachusetts Eye and Ear Infirmary: Analysis of treatment indications and postinjection endophthalmitis rates Br J Ophthalmol. 2013;97:460–5
13. Moshfeghi AA, Rosenfeld PJ, Flynn HW Jr, Schwartz SG, Davis JL, Murray TG, et al Endophthalmitis after intravitreal vascular [corrected] endothelial growth factor antagonists: A six-year experience at a university referral center Retina. 2011;31:662–8
14. Fineman MS, Hsu J, Spirn MJ, Kaiser RS. Bimanual assisted eyelid retraction technique for intravitreal injections Retina. 2013;33:1968–70
15. Shimada H, Hattori T, Mori R, Nakashizuka H, Fujita K, Yuzawa M. Minimizing the endophthalmitis rate following intravitreal injections using 0.25% povidone-iodine irrigation and surgical mask Graefes Arch Clin Exp Ophthalmol. 2013;251:1885–90
16. Lyall DA, Tey A, Foot B, Roxburgh ST, Virdi M, Robertson C, et al Post-intravitreal anti-VEGF endophthalmitis in the United Kingdom: Incidence, features, risk factors, and outcomes Eye (Lond). 2012;26:1517–26
17. Comparison of Age-related Macular Degeneration Treatments Trials (CATT) Research Group. Martin DF, Maguire MG, Fine SL, Ying GS, Jaffe GJ, et al Ranibizumab and bevacizumab for treatment of neovascular age-related macular degeneration: Two-year results Ophthalmology. 2012;119:1388–98
18. IVAN Study Investigators. Chakravarthy U, Harding SP, Rogers CA, Downes SM, Lotery AJ, et al Ranibizumab versus bevacizumab to treat neovascular age-related macular degeneration: One-year findings from the IVAN randomized trial Ophthalmology. 2012;119:1399–411
19. Horster S, Bader L, Seybold U, Eschler I, Riedel KG, Bogner JR. Stenotrophomonas maltophilia induced post-cataract-surgery endophthalmitis: Outbreak investigation and clinical courses of 26 patients Infection. 2009;37:117–22
20. Chang JS, Flynn HW Jr, Miller D, Smiddy WE. Stenotrophomonas maltophilia endophthalmitis following cataract surgery: Clinical and microbiological results Clin Ophthalmol. 2013;7:771–7
21. Williams MA, Gramajo AL, Colombres GA, Caeiro JP, Juárez CP, Luna JD. Stenotrophomonas maltophilia endophthalmitis caused by surgical equipment contamination: An emerging nosocomial infection J Ophthalmic Vis Res. 2014;9:383–7
22. Ji Y, Jiang C, Ji J, Luo Y, Jiang Y, Lu Y. Post-cataract endophthalmitis caused by multidrug-resistant Stenotrophomonas maltophilia: Clinical features and risk factors BMC Ophthalmol. 2015;15:14
23. Chen KJ, Wang NK, Sun MH, Chen TL, Lai CC, Wu WC, et al Endophthalmitis caused by Stenotrophomonas maltophilia Ophthalmic Surg Lasers Imaging. 2010;41:e555–61
24. Penland RL, Wilhelmus KR. Stenotrophomonas maltophilia ocular infections Arch Ophthalmol. 1996;114:433–6
25. Kumar A. Guidelines for Intravitreal Injections 2016Last accessed on 2016 Feb 08 Available from:

Cluster endophthalmitis; intravitreal Avastin; Stenotrophomonas maltophilia; VITEK™

© 2017 Indian Journal of Ophthalmology | Published by Wolters Kluwer – Medknow