Stenotrophomonas maltophilia endophthalmitis following cataract surgery: clinical and microbiological results

A rare case of Stenotrophomonas maltophilia endogenous endophthalmitis in pediatric age group

BACKGROUND

We report a unique case of Stenotrophomonas maltophilia-related pediatric endogenous endophthalmitis.

CASE PRESENTATION

A 10-year-old male presented with redness and loss of vision in his right eye for two weeks. Clinical examination and ultrasound features were suggestive of endophthalmitis, most likely endogenous due to the absence of a history of trauma or intraocular intervention. Following vitrectomy and appropriate intravitreal antibiotics, the vision improved to 20/80. Vitreous culture revealed a gram-negative bacillus Stenotrophomonas maltophilia.

CONCLUSION

Timely recognition of this pathogen and management as per antibiotic sensitivity can help salvage functional vision in this condition.

POSTINTRAVITREAL INJECTION AND POSTCATARACT EXTRACTION ENDOPHTHALMITIS VISUAL OUTCOMES BY ORGANISM: A SYSTEMATIC REVIEW AND META-ANALYSIS

PURPOSE

To compare visual outcomes of endophthalmitis following intravitreal injections (IVIs) and cataract extraction by causative organism.

METHODS

Searches in Cochrane Central Register of Controlled Trials, MEDLINE, and Embase identified articles reporting visual outcomes by causative organisms in post-IVI and cataract extraction endophthalmitis cases from January 2010 to February 2022. A random-effects meta-analysis compared visual improvement among endophthalmitis cases caused by causative organisms.

RESULTS

Eighty-five out of 3,317 retrieved studies were included. The highest degree of visual acuity improvement in both post-IVI and postcataract extraction endophthalmitis was seen in cases caused by coagulase-negative staphylococci, followed by gram-negative organisms and other gram-positive organisms such as streptococci and enterococci. Culture-negative cases showed more visual acuity improvement than culture-positive cases in post-IVI endophthalmitis. These results remained consistent when accounting for endophthalmitis treatment, IVI type, condition requiring IVI treatment, follow-up period, and initial preprocedural visual acuity.

CONCLUSION

Coagulase-negative staphylococci and gram-negative organisms show the most visual acuity improvement in both post-IVI and postcataract extraction endophthalmitis. Other gram-positive organisms such as streptococci and enterococci are associated with less visual improvement. This updated systematic review and meta-analysis revealed that the results of the Endophthalmitis Vitrectomy Study are consistent decades later despite advancements in surgical practices and the evolution of microorganisms over time.

Triple Gram-negative bacterial endophthalmitis following intravitreal injection

PURPOSE

To describe a puzzling case of endophthalmitis caused by three unusual bacteria after intravitreal injection, its outcome, and underlying questions.

FINDINGS

A 70-year-old female patient was diagnosed with acute endophthalmitis following intravitreal aflibercept injection for age-related macular degeneration. A standard tap and inject procedure was performed. Microbiological analyses on the anterior chamber and vitreous samples yielded the presence of three non-fermenting Gram-negative rods: Pseudomonas stutzeri, Stenotrophomonas maltophilia, and Ochrobactrum anthropi. The outcome was favorable after intravitreal injections of vancomycin and ceftazidime, with an almost complete recovery of the visual acuity to its baseline level. No potential source of infection was identified.

CONCLUSION

Endophthalmitis following intravitreal injection can be caused by a wide variety of bacteria, including some rare Gram-negative species. They can sometimes co-exist in a single patient, but their virulence may vary greatly. Due to the variable antibiotic susceptibility and frequent multiresistance associated with non-fermenting Gram-negative rods, a prompt microbiological approach is required. Favorable outcome can be achieved with standard management.

Stenotrophomonas maltophilia endophthalmitis following keratoplasty

Endophthalmitis is among the most sight-threatening infections in ophthalmology practice. Many microorganisms causing endophthalmitis have been reported. Stenotrophomonas maltophilia is among the rare causes of endophthalmitis and has been reported after cataract surgery, intravitreal injections and ocular trauma. We report a case of S. maltophilia endophthalmitis after keratoplasty, which is a rare entity, in a 63-year-old female patient.

Ocular Bacterial Infections: A Ten-Year Survey and Review of Causative Organisms Based on the Oklahoma Experience

Ocular infections can be medical emergencies that result in permanent visual impairment or blindness and loss of quality of life. Bacteria are a major cause of ocular infections. Effective treatment of ocular infections requires knowledge of which bacteria are the likely cause of the infection. This survey of ocular bacterial isolates and review of ocular pathogens is based on a survey of a collection of isolates banked over a ten-year span at the Dean McGee Eye Institute in Oklahoma. These findings illustrate the diversity of bacteria isolated from the eye, ranging from common species to rare and unique species. At all sampled sites, staphylococci were the predominant bacteria isolated. Pseudomonads were the most common Gram-negative bacterial isolate, except in vitreous, where Serratia was the most common Gram-negative bacterial isolate. Here, we discuss the range of ocular infections that these species have been documented to cause and treatment options for these infections. Although a highly diverse spectrum of species has been isolated from the eye, the majority of infections are caused by Gram-positive species, and in most infections, empiric treatments are effective.

Antimicrobial Susceptibility, Minimum Inhibitory Concentrations, and Clinical Profiles of Stenotrophomonas maltophilia Endophthalmitis

Stenotrophomonas maltophilia has been reported in various ocular infections, including keratitis, conjunctivitis, preseptal cellulitis, and endophthalmitis, all of which may lead to vision loss. However, the S. maltophilia strain is resistant to a wide variety of antibiotics, including penicillins, third-generation cephalosporins, aminoglycosides, and imipenem. In this study, we retrospectively reviewed the clinical characteristics, antibiotic susceptibility, antimicrobial minimum inhibitory concentrations (MICs), and visual outcomes for S. maltophilia endophthalmitis. The data of 9 patients with positive S. maltophilia cultures in a tertiary referral center from 2010 to 2019 were reviewed. Cataract surgery (n  =  8, 89%) was the most common etiology, followed by intravitreal injection (n  =  1, 11%). S. maltophilia’s susceptibility to levofloxacin and moxifloxacin was observed in 6 cases (67%). Seven isolates were resistant to sulfamethoxazole-trimethoprim (78%). The MIC₉₀ for S. maltophilia was 256, 256, 256, 8, 12, 12, 12, and 8 μg/mL for amikacin, cefuroxime, ceftazidime, tigecycline, sulfamethoxazole-trimethoprim, levofloxacin, galtifloxacin, and moxifloxacin, respectively. Final visual acuity was 20/200 or better in 5 patients (56%). Fluoroquinolones and tigecycline exhibited low antibiotic MIC₉₀. Therefore, the results suggest that fluoroquinolones can be used as first-line antibiotics for S. maltophilia endophthalmitis.

Comparative Analysis of the Clinical Aspects and Treatment Outcomes of Stenotrophomonas maltophilia Keratitis and Pseudomonas aeruginosa Keratitis

OBJECTIVES

We analyzed the clinical aspects and treatment outcomes of Stenotrophomonas maltophilia (SM) keratitis and Pseudomonas aeruginosa (PA) keratitis.

METHODS

Medical records of 55 inpatients with culture-proven SM (n=21) and PA (n=34) keratitis were retrospectively reviewed. Predisposing factors, clinical characteristics, and treatment outcomes were compared between the SM and PA groups.

RESULTS

The mean symptom duration was longer in the SM group than in the PA group (10.4:4.3 days; P=0.012). The most common predisposing factor was corneal trauma (47.6%) in the SM group and contact-lens wear (38.2%) in the PA group. There were no differences in the mean epithelial defect size (12.7:11.9 mm2; P=0.861), hypopyon (33.3%:44.1%; P=0.428), surgical treatment (4.8%:14.7%; P=0.390), or poor clinical outcomes (26.8%:30.3%; P=0.760) between the SM and PA groups. In multivariate logistic regression, risk factors for poor clinical outcomes were hypopyon (odds ratio [OR], 52.00; P=0.010) in the SM group and symptom duration≥7 days (OR, 44.32; P=0.015), age≥60 years (OR, 21.13; P=0.019), and hypopyon (OR, 15.20; P=0.038) in the PA group.

CONCLUSION

Compared with PA keratitis, SM keratitis had slower progression, and its clinical characteristics and treatment results were not worse. In both groups, hypopyon was the risk factor for a poor clinical outcome.

Advances in the Microbiology of Stenotrophomonas maltophilia

Stenotrophomonas maltophilia is an opportunistic pathogen of significant concern to susceptible patient populations. This pathogen can cause nosocomial and community-acquired respiratory and bloodstream infections and various other infections in humans. Sources include water, plant rhizospheres, animals, and foods. Studies of the genetic heterogeneity of S. maltophilia strains have identified several new genogroups and suggested adaptation of this pathogen to its habitats. The mechanisms used by S. maltophilia during pathogenesis continue to be uncovered and explored. S. maltophilia virulence factors include use of motility, biofilm formation, iron acquisition mechanisms, outer membrane components, protein secretion systems, extracellular enzymes, and antimicrobial resistance mechanisms. S. maltophilia is intrinsically drug resistant to an array of different antibiotics and uses a broad arsenal to protect itself against antimicrobials. Surveillance studies have recorded increases in drug resistance for S. maltophilia, prompting new strategies to be developed against this opportunist. The interactions of this environmental bacterium with other microorganisms are being elucidated. S. maltophilia and its products have applications in biotechnology, including agriculture, biocontrol, and bioremediation.

Clinical and Optical Coherence Tomography Angiographic Features in Patients with Postcataract Stenotrophomonas maltophilia Endophthalmitis

Purpose

To report the clinical presentations and optical coherence tomography (OCT) angiographic features of patients with postcataract surgery endophthalmitis due to Stenotrophomonas maltophilia. Methods. A retrospective observational study of 4 patients who developed S. maltophilia endophthalmitis after cataract surgery. Pars plana vitrectomy (PPV) was performed to control the infection. Patients were followed up for six months. Complete ophthalmological examination results were collected before and after PPV.

Results

Patients' response to PPV therapy was excellent and the infection was cured in all cases. OCTA showed that, at the one-month follow-up, the vascular density (VD) and perfusion density (PD) in the superficial capillary plexus (SCP) were significantly lower than those in healthy collateral eyes. As time went on, the SCP-VD and SCP-PD values gradually improved.

Conclusions

With early PPV, the infection caused by S. maltophilia can be cured. OCTA provides a quantitative noninvasive assessment to evaluate the severity and prognosis of patients with S. maltophilia endophthalmitis.

Bacterial contamination of intravitreal needles by the ocular surface microbiome

PURPOSE

The ocular surface microbiota are recognised as one of causative microorganisms in post-procedural endophthalmitis but in many cases the vitreous tap is culture negative. This study investigated bacterial contamination of intravitreal (IVT) needles using multiple approaches covering culturing, 16S rRNA gene sequencing, fluorescent in situ hybridisation (FISH) and scanning electron microscopy (SEM).

METHODS

IVT needles were obtained immediately after injection from patients undergoing treatment for predominantly age-related macular degeneration. Eighteen needles were analysed by culturing on chocolate blood agar. In addition, 40 needles were analysed by extracting DNA and paired-end sequencing of the 16S rRNA gene. Sequences were quality filtered (USEARCH), taxonomically classified (SILVA) and contaminant filtered (DECONTAM). Nine needles were analysed by either FISH using the bacterial probe EUB338 or SEM.

RESULTS

Using culturing, three bacteria were identified from 5 of 18 needles (28%) - Kocuria kristinae, Staphylococcus hominis and Sphingomonas paucimobilis. The negative control needles showed no growth. Following rigorous data filtering, bacterial community analysis using 16S rRNA gene sequencing showed the presence of predominantly Corynebacterium but also Pseudomonas, Acinetobacter, Sphingomonas, Staphylococcus and Bacillus on the needles. Cocci-shaped cells in a tetrad formation were observed using FISH, while SEM images showed cocci-shaped bacteria in pairs and irregular tetrads.

CONCLUSIONS

The study showed evidence for a large diversity of bacteria on IVT needles and visually confirmed their adherence. The diversity was similar to that found on the ocular surface and in conjunctival tissue. This suggests the risk of exogenous endophthalmitis remains even with sterilization of the conjunctival surface.

STENOTROPHOMONAS MALTOPHILIA ENDOPHTHALMITIS 1 MONTH AFTER INTRAVITREAL AFLIBERCEPT

PURPOSE

Endophthalmitis caused by Stenotrophomonas maltophilia is rare and has been described after cataract surgery and open globe injuries. We report a patient with endophthalmitis caused by this organism after uncomplicated intravitreal aflibercept injection.

METHODS

A 70-year-old man with a history of anti-vascular endothelial growth factor therapy for diabetic macular edema presented 23 days after aflibercept injection with clinical diagnosis of endophthalmitis. The patient initially had mild pain, conjunctival congestion, and anterior chamber cell; 2 days later, the patient returned with hand motion visual acuity, hypopyon, and dense vitritis.

RESULTS

A tap and inject procedure was performed. The aqueous sample confirmed the presence of S. maltophilia. Antimicrobial testing showed susceptibility to ceftazidime which was used during the initial treatment. After resolution of the vitritis and hypopyon, the visual acuity returned to 20/70 at his 3-month follow-up examination.

CONCLUSION

Stenotrophomonas maltophilia is a rare infectious agent associated with intravitreal injection and may present 1 month after treatment.

Identification and Visualization of a Distinct Microbiome in Ocular Surface Conjunctival Tissue

Purpose

Knowledge of whether microorganisms reside in protected niches of the conjunctiva is potentially significant in terms of minimizing risks of contact lens inflammation/infection and endophthalmitis. We define if and how microbial communities from limbal and forniceal conjunctival tissue differ from those on the conjunctival surface.

Methods

Human limbal and forniceal conjunctival tissue was obtained from 23 patients undergoing pterygium surgery and analyzed with data from a recent study of conjunctival surface swabs (n = 45). Microbial communities were analyzed by extracting total DNA from tissue samples and surface swabs and sequencing the 16S rRNA gene using the Illumina MiSeq platform. Sequences were quality filtered, clustered into operational taxonomic units (OTUs) at 97% similarity. OTUs associated with blank extraction and sampling negative controls were removed before analysis. Fluorescent in situ hybridization (FISH) was performed on cyrosections of limbal and forniceal conjunctival tissue.

Results

There was a significant difference in bacterial community structure between the conjunctival surface and fornix (P = 0.001) and limbus (P = 0.001) tissue. No difference was found in bacterial communities between the limbus and fornix (P = 0.764). Fornix and limbal samples were dominated by OTUs classified to the genus Pseudomonas (relative abundance 79.9%), which were found only in low relative abundances on conjunctival surfaces (6.3%). Application of FISH showed the presence of Pseudomonas in the forniceal tissue sample.

Conclusions

There is a discrete tissue-associated microbiome in freshly-collected human limbal and fornix tissue, which is different from the microbial community structure and composition of the ocular surface microbiome.

Stenotrophomonas maltophilia: An emerging entity for cluster endophthalmitis

PURPOSE

This was a study of acute cluster endophthalmitis along with clinical features, culture results, and visual outcomes of 10 eyes of 10 patients after intravitreal injection of Avastin (bevacizumab) in one sitting from a single vial.

METHODS

Retrospective review of intravitreal injection of 1.25 mg/0.05 ml bevacizumab that was given to 10 eyes of 10 patients on the same day from a freshly opened vial. All patients manifested with endophthalmitis the next day. Vitreous tap for direct smear and culture was done. Intravitreal antibiotics and steroids were injected and appropriate treatment begun. The injection vial of the same batch was sent for VITEKTM identification and antimicrobial susceptibility of isolates.

RESULTS

Endophthalmitis presented within 24 h of intravitreal injection. There was a remarkable absence of posterior pupillary synechia. Two cases were culture-positive (20%), showing pseudomonoid growth. The vial of the same batch revealed a pseudomonoid bacilli Stenotrophomonas maltophilia using VITEKTM, which was resistant to multiple drugs. Hence, the contaminated vial was identified as the source of infection in our case. Among 10 patients, two underwent pars plana vitrectomy. Visual acuity returned to preendophthalmitis levels in 9/10 eyes after 1 month. One patient was lost to follow-up. Late complications included retinal detachment in one case and neovascular glaucoma in another.

CONCLUSION

Early recognition and treatment are key factors in improving outcomes. Causative etiology could be microbial contamination of the drug vial. S. maltophilia should be considered a pathogenic organism of postintravitreal endophthalmitis.

Increase in the Prevalence of Resistance Determinants to Trimethoprim/Sulfamethoxazole in Clinical Stenotrophomonas maltophilia Isolates in China

Aims

This study was carried to reveal the genetic mechanisms of trimethoprim/sulfamethoxazole (SXT) resistance.

Methods

Among 300 clinical Stenotrophomonas maltophilia isolates from China, resistance determinants such as sul and dfrA genes, integrons and transposase were examined using PCR, DNA sequencing and thermal asymmetric interlaced PCR (TAIL-PCR). Data were analyzed using SPSS 20.0.

Results

Of the 300 isolates, 116 (38.7%) were resistant to SXT. An alarming trend of increased resistance to SXT were found over the 10-year period. The positive rates of sul and class 1 integrase (intI1) increased gradually with the development of SXT resistance over the 10-year period. Multiple logistic regression analyses indicated that the genes of qacEΔ1-sul1 (81% vs 46.2%, p = 0.000), sul2 (50.9% vs 9.8%, p = 0.000), intI1 (83.6% vs 65.8%, p = 0.000), dfrA12 (25% vs 3.3%, p = 0.000), dfrA17 (15.5% vs 3.8%, p = 0.000) and dfrA27 (4.3% vs 1.6%, p = 0.01) were more prevalent in SXT-resistant isolates than SXT-susceptible isolates except dfrA1(p = 0.83) and dfrA5(p = 0.18). Sequencing data revealed 12 types of resistance gene cassettes (aar-3-dfrA27, dfrA12–aadA2, dfrA17–aadA5, cmlA1, aacA4, aadA5, arr-3-aacA4, aadA1, aadB–aadA4, aacA4–catB8–aadA1, aadB–aac(6′)-II–bla_CARB-8 and aac(6′)-II–bla_CARB-8) located in the class 1 integron in 163 isolates (87% SXT-resistant vs 33.7% SXT-susceptible isolates, p = 0.000). A novel finding was the aar-3-dfrA27 (KC748137) gene cassette. The gene of sul2 linked to transposase in 50 SXT- resistant and 7 SXT- susceptible isolates was detected by TAIL-PCR.

Conclusions

The findings demonstrated a higher prevalence of sul, dfrA, intI1 and resistance gene cassettes in class 1 integron in SXT-resistant clinical S. maltophilia isolates in China. The sul1 and dfrA genes located in integrons and the sul2 linked to transposase may imply wide and rapid dissemination of resistance gene in bacteria.

Prophylactic removal and microbiological evaluation of calcified plaques after pterygium surgery

PURPOSE

The aim of this study was to investigate microbiological characteristics of prophylactically removed calcified plaques developed after pterygium excision, and to evaluate risk factors for the growth of microorganisms.

METHODS

Only exposed calcified plaques developed at the same site of previous pterygium excision were prospectively removed in 15 eyes of 14 patients. Plaques were completely removed, divided into small pieces and evaluated for microbiological identification. Underlying scleral defects were reconstructed using a conjunctival autograft, amniotic membranes and scleral patch grafts according to the size and depth of the defects. Based on the results of microbiologic cultures, eyes were divided into two groups and risk factors for microbial growth were analyzed.

RESULTS

At surgery, the mean age of the patients was 71.2 ± 5.8 years and 71.4 % were females. The mean time interval between pterygium excision and calcified plaque removal was 19.3 ± 13.8 years. Six of 15 (40 %) removed plaques showed bacterial growth, and Stenotrophomonas maltophilia was the most frequently isolated microorganism. The size of calcified plaques was the only risk factor for culture-positive results (p = 0.045). Underlying scleral defects were successfully repaired without any serious complication.

CONCLUSIONS

Microorganisms can be isolated from calcified plaques developed at the site of previous pterygium excision, and the size of plaques is the only risk factor for culture-positive results. To remove potential source of infection, prophylactic removal of calcified plaques and scleral surface reconstruction should be considered, especially when the plaques are exposed and large.

Conjunctival flora of clinically normal and diseased turtles and tortoises

BACKGROUND

In captive breed turtles and tortoises conjunctival disease is common. Our aim was to investigate the bacterial and fungal flora present in the eyes of healthy and pathological chelonians and to compare findings in turtles with those in tortoises.

RESULTS

Samples were taken from the conjunctival sacs of 34, diseased and healthy, chelonians (18 tortoises and 16 turtles) and submitted to bacterial and fungal investigation. All samples showed bacterial growth. Thirteen animals (38%), harboured a single bacterial species as sole isolate and twenty-one animals (62%) harboured more than one species. Detection of multiple bacterial infection was clearly greater in tortoises compared to turtles. Most frequently isolated bacterial species were Bacillus spp. (13 isolates), Staphylococcus xylosus (10 isolates), Sphingomonas paucimobilis (6 isolates), Staphylococcus sciuri and Aeromonas hydrophila/caviae (each 5 isolates), Ochrobactrum anthropi (3 isolates), Citrobacter freundii, Enterobacter cloacae and Pseudomonas luteola (each 2 isolates). Only one isolate of Kocuria varians/rosea, Staphylococcus aureus, Staphylococcus auricularis, Staphylococcus haemolyticus, Staphylococcus lentus, Morganella morganii, Pasteurella multocida, Pasteurella pneumotropica/haemolytica, Proteus spp., Pseudomonas putida, Salmonella enterica ssp. arizonae, Stenotrophomonas maltophilia and Vibrio parahaemolyticus was evidenced. The presence in 8 animals of Mycoplasma spp. and in 1 animal with severe conjunctivitis of Chlamydia spp. was detected by PCR. Candida spp. was also isolated from two healthy animals.

CONCLUSIONS

A clear predominance of Gram positive isolates in tortoises and Gram negative isolates in turtles was found. However, we cannot ascribe the observed difference to the diversity of animal species, as other factors, including especially different characteristics of the living environments, may play a role. Almost all bacterial species isolated may have clinical significance, mostly as opportunistic pathogens, both for humans and animals. That chelonians are often carrier of bacteria with zoonotic potential is a well-known fact, in particular with regard to Salmonella spp. Therefore, it is not surprising the detection of a strain of Salmonella enterica ssp. arizonae in the eye of one of the animals tested. Worthy of note is the finding of Chlamydia spp. in a severe case of conjunctivitis, though we cannot epidemiologically assess a cause-effect relationship between presence of chlamydia and disease.

Post-cataract endophthalmitis caused by multidrug-resistant Stenotrophomonas maltophilia: clinical features and risk factors

Background

To report clinical features and risk factors of post-cataract surgery endophthalmitis (PE) due to Stenotrophomonas maltophilia.

Methods

A retrospective case review from December 10, 2010 to April 7, 2011 was performed at the Eye & ENT Hospital, Fudan University. Data were collected for surgical details, disease characteristics, antibiotic sensitivity of the pathogen, and treatment response. Visual outcomes were examined with a minimum follow-up of 12 months.

Results

Fourteen cases of S. maltophilia endophthalmitis were identified. The onset of infection occurred from 1–56 days postoperatively (median, 13.5 days). Obvious cellular reactions were found in all patients in the anterior chamber, along with the absence of pupil synechia. Retinal periphlebitis was an early sign of PE. S. maltophilia was positive in eight patients (57.1%). The fluids from aspiration tubes revealed the same bacteria, which were resistant to multiple drugs (e.g., amino glycosides, most of the β-lactams, aztreonam, imipenem, and ciprofloxacin), except levofloxacin. Compared with the culture-negative group, the infection was more rapid, more severe, and more difficult to control in the culture-positive group. Among 14 patients, 11 patients (78.6%) underwent pars plana vitrectomy (PPV) with intravitreal injection. Three patients had PPV twice, and three patients had intraocular lens and capsular bag removal. A final visual acuity of ≥20/100 was achieved by 13/14 patients (92.9%). Complications included retinal detachment in three cases (21.4%) and recurrence of infection in two cases (14.8%). Statistical analysis showed that age over 90 years and posterior capsule rupture were risk factors of infection (P = 0.034 and P = 0.034, respectively). The phacoemulsifier allowed potential contamination between the aspiration and irrigation tubes.

Conclusions

S. maltophilia should be considered a pathogenic organism of PE. The infection often occurs in older patients with posterior capsule rupture. Intravitreal or systemic administration of effective antibiotics and earlier initial PPV may contribute to better clinical outcomes. Tubes with connections between aspiration and irrigation should be avoided during surgery.

Chronic dacryocystitis secondary to Stenotrophomonas maltophilia and Staphylococcus aureus mixed infection

A 40-year-old woman with a history of recurrent attacks of dacryocystitis for 2 years developed a lacrimal sac abscess. β-Lactam antibiotics, considered the first-line treatment for dacryocystitis, were ineffective. She underwent dacryocystorhinostomy. Cultures from the lacrimal sac demonstrated the presence of Stenotrophomonas maltophilia and methicillin-sensitive Staphylococcus aureus, both of which are sensitive to trimethoprim-sulfamethoxazole. This rare and antibiotic-resistant bacterial species should be considered in atypical cases of dacryocystitis, and appropriate antibiotics should be started immediately.