Successful use of intravitreal and systemic colistin in treating multidrug resistant Pseudomonas aeruginosa post-operative endophthalmitis

Antibiotic susceptibility in Endophthalmitis Management Study and intravitreal antibiotic practice trend in India-EMS Report #5

AIM

Analyze antibiotic susceptibility in the Endophthalmitis Management Study (EMS) and compare it with the current intravitreal antibiotic practice trend of members of the Vitreoretinal Society of India (VRSI) practicing in India.

METHODS

The microbiology work-up of undiluted vitreous included microscopy, culture-susceptibility, polymerase chain reaction (PCR), and next-generation sequencing (NGS). VRSI members were invited to the survey. The EMS conventional culture-susceptibility (PCR and NGS excluded) results were compared vis-a-vis gram-positive cocci (GPC), gram-negative bacilli (GNB), and less commonly used antibiotics with the current recommended intravitreal antibiotics. p < 0.05 was considered significant.

RESULTS

Culture and positivity (culture + PCR/NGS) positivity was 28.8% and 56.1%, respectively. GPC was most susceptible to cefazolin, linezolid, and vancomycin; GNB was most susceptible to amikacin, ceftazidime, colistin, and imipenem. There was no susceptibility difference between cefazolin and vancomycin (p = 0.999) and between ceftazidime and imipenem (p = 1.0). Colistin was superior to ceftazidime (p = 0.047) against GNB. The GNB resistant to amikacin (n = 14) were equally susceptible to ceftazidime and colistin; resistant to ceftazidime (n = 16) were susceptible to colistin; and resistant to colistin (n = 7) were susceptible to ceftazidime. The preference of VRSI members (n = 231) practicing in India was a vancomycin-ceftazidime combination (82%), vancomycin for GPC (94%), ceftazidime for GNB (61%), and voriconazole for fungi (74%).

CONCLUSION

In EMS, GPC had good susceptibility to vancomycin; GNB had good susceptibility to ceftazidime and colistin. Given the lower resistance of colistin, a vancomycin-colistin combination could be an alternative empiric treatment in post-cataract endophthalmitis in India.

Evaluating the utility of inflammation score in post-cataract surgery endophthalmitis. Results from a prospective study in India. EMS Report #4

PURPOSE

To investigate if inflammation score (IS), calculated from the cornea, anterior chamber, iris, and vitreous, indicates endophthalmitis severity.

METHODS

In a prospective study, consecutive adults with a clinical diagnosis of post-cataract endophthalmitis within 6 weeks of surgery were recruited. Patients were allocated to IS-based primary treatment (IS < 10: intravitreal injection and IS ≥ 10: vitrectomy) and randomized to two intravitreal antibiotics combinations (vancomycin + ceftazidime and vancomycin + imipenem). Undiluted vitreous microbiology work-up included culture susceptibility, polymerase chain reaction, Sanger sequencing, and targeted next-generation sequencing.

RESULTS

The average age of 175 people was 63.4 ± 10.7 years and included 52.6% small incision cataract surgery and 47.4% phacoemulsification surgery. Severe endophthalmitis (IS ≥ 20), diagnosed in 27.4% of people, had a shorter time to symptoms (average 5.4 vs 8.7 days; P = 0.018), poorer presenting vision (all ≤ hand motion), higher culture positivity (50% vs 30.7%; P = 0.032), and higher Gram-negative bacterial infection (70.8% vs 46.2%; P = 0.042). For IS ≥ 20 discriminant and Gram-negative infection, Spearman's coefficient was 0.7 [P < 0.0001, 95% confidence interval (CI) 0.59-0.82], with an area under the receiver operating characteristic curve of 0.9 (95% CI 0.85-0.94, P < 0.0001), a Youden index J of 0.74, a sensitivity of 87.2%, and a specificity of 87.5%. The final vision of >20/400 and >20/100 was regained in 50.2% and 29.1% of people, respectively. The susceptibility of common Gram-positive cocci and Gram-negative bacilli was the highest for vancomycin (95.0%) and colistin (88.6%), respectively. NGS detected polymicrobial infection in 88.5% of culture-negative endophthalmitis.

CONCLUSIONS

Higher inflammation scores indicated severe disease and Gram-negative infection in post-cataract endophthalmitis.

Clinical settings, management and factors affecting outcomes in multi and extensively-drug resistant Pseudomonas endophthalmitis

PURPOSE

To report the clinical settings, management and factors affecting outcomes in multi-drug resistant (MDR) and extensively-drug resistant (XDR) Pseudomonas endophthalmitis.

SETTINGS

Retrospective, consecutive, non-comparative interventional case series. Cases of MDR and XDR Pseudomonas endophthalmitis from January 2012 to December 2020 treated at our tertiary eye care center were included. Data collected included clinical data, anatomic and functional outcome, isolated micro-organisms, and culture sensitivity.

RESULTS

This study included 29 eyes of 29 patients with MDR/XDR Pseudomonas endophthalmitis. Mean age at presentation was 60.27 ± 14.9 years (median 63). Commonest clinical setting was acute post-operative endophthalmitis in 27 cases (93.1%). Concurrent corneal infiltrate was present in 11 eyes (37.9%). Initial intervention in 19 eyes (65.5%) was vitrectomy, 2 of which underwent endoscopic pars plana vitrectomy. Mean number of interventions was 3.34 ± 1.44 (median 4). Mean follow up was 3.25 ± 3.07 months (median 2). Sensitivity to ceftazidime was 48.28%. All isolates were sensitive to colistin. Mean visual acuity at last follow up in logMAR was 2.64 ± 1.48 (median 3.5). Seven eyes (24.13%) were NPL (nil perception of light) at the last follow up. Two eyes (6.9%) underwent evisceration. Nine eyes (31.03%) had a favourable anatomic and functional outcome. Eyes without a corneal infiltrate at presentation were found to have a favourable anatomic and favourable functional outcome (OR 11.91, P < 0.04, CI 1.08 to 130.93).

CONCLUSION

Corneal involvement at presentation is associated with poorer outcomes in MDR and XDR Pseudomonas endophthalmitis. There is a potential role of higher newer antibiotics especially colistin in the management of these cases.

ALTERNATIVE INTRAVITREAL ANTIBIOTICS: A Systematic Review for Consideration in Recalcitrant or Resistant Endophthalmitis

PURPOSE

To organize, categorize, and create a quick reference guide for the use of intravitreal antibiotic alternatives to the standard combination of vancomycin and ceftazidime for the treatment of endophthalmitis.

METHODS

A systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Review and Meta-Analyses guidelines. The authors searched for all available information regarding intravitreal antibiotics in the last 21 years. Manuscripts were selected according to relevance, level of information, and the available data regarding intravitreal dose, potential adverse effects, bacterial coverage, and relevant pharmacokinetic information.

RESULTS

The authors included 164 of 1810 manuscripts. The antibiotics were classified according to their class into fluoroquinolones, cephalosporins, glycopeptide and lipopeptide, penicillins and beta-lactams, tetracyclines, and miscellaneous. The authors also included information regarding intravitreal adjuvants for the treatment of endophthalmitis and one ocular antiseptic.

CONCLUSION

The treatment of infectious endophthalmitis is a therapeutic challenge. The current review summarizes the properties of possible intravitreal antibiotic alternatives that should be considered in cases of suboptimal response to initial treatment.

Endophthalmitis Management Study-A Prospective Randomized Clinical Trial on Postoperative Endophthalmitis Management in India: An Interim Analysis. Endophthalmitis Management Study Report #3

PURPOSE

An interim analysis of the Endophthalmitis Management Study to examine the outcome of inflammation score (IS)-based treatment and antibiotic susceptibility.

DESIGN

A prospective randomized study.

PATIENTS AND METHODS

IS was measured on a 0-4 scale from presenting signs in 4 cardinal ocular tissues. The eyes with IS <10 received vitreous tap and intravitreal antibiotics, whereas eyes with IS ≥10 received vitrectomy and intravitreal antibiotics. These eyes were randomized to 2 intravitreal antibiotic combinations: (1) vancomycin and ceftazidime and (2) vancomycin and imipenem. Microbiology workup of undiluted vitreous included microscopy, culture-susceptibility, Sanger, and targeted next-generation sequencing. The clinical and microbiology outcomes were analyzed for advanced (IS = ≥20) and less advanced (IS = <10) endophthalmitis.

RESULTS

Interim analysis was performed after the Endophthalmitis Management Study recruited 56.85% (248/436) of patients and completed 54.6% (238/436) of microbiology workup. A 90-day follow-up was completed in 90.8% (168/185) of eligible people. In eyes with IS ≥20, the time to symptoms was shorter (5.8 ± 6.7 vs 8.5 ± 9.1 d; P = 0.015), and the need for additional treatment was higher (95.8% vs 53.1%; P = 0.0267). Good final vision was associated with good presenting vision (r = 0.30) and IS-based treatment decisions (r = 0.170). Microbiology positivity was 55.9%. Eyes with IS <10 had a higher Gram-positive cocci (33.9% vs 4.8%; P = 0.013) infection. Gram-positive cocci were most susceptible to vancomycin (95.7%), and Gram-negative bacilli to colistin (95.7%).

CONCLUSIONS

Considering both IS and presenting vision, rather than only one of them, helps in making appropriate management decisions for acute postoperative endophthalmitis.

Determination of the retinal toxicity of intravitreal colistin in rabbit eyes

PURPOSE

To determine the possible adverse effects and safe dose range of intravitreal colistin, an antibiotic, after its intravitreal application.

METHODS

Twenty eyes of 20 adult male and female New Zealand white rabbits were selected. Various concentrations of colistin were prepared. In each rabbit, 0.1 mL of colistin solution or saline solution was injected intravitreally into the right eye. Electroretinographic recordings were taken before and 2 weeks after injection. Histopathological examination was made using a light microscope following enucleation and fixation procedures. In histopathologic cross-sections, the differences between drug-injected eyes and control eyes were evaluated.

RESULTS

Electroretinographic examination showed a decrease of 30% as a significant value in the a and b wave amplitudes of the rabbits that injected 400 µg/0.1 ml and higher concentrations. Histological examination revealed histiocytic infiltration, histiocytic vacuoles, inflammation, and retinal degeneration in rabbit eyes given 400 µg/0.1 ml, 800 µg/0.1 ml, and 1.6 mg/0.1 ml concentrations of colistin.

CONCLUSION

Based on our findings, the safe concentration of colistin is 0.2 mg/0.1 ml. Administration of 0.4 mg/0.1 ml was associated with cataract development, electrophysiological depression, and pathological changes in retinal layers.

Antibiotic sensitivity trends of pseudomonas endophthalmitis in a tertiary eye care center in South India: A 12-year retrospective study

Purpose:

To assess trends in antibiotic sensitivity of pseudomonas and compare multidrug resistance (MDR) between Pseudomonas endophthalmitis cases presenting in two consecutive 6-year time frames in a tertiary center in South India.

Methods:

This is a retrospective comparative series of all Pseudomonas endophthalmitis cases treated from June 2004 to May 2016. Microbiological culture results in all endophthalmitis patients were screened for pseudomonas. Positive cases in the initial 6 and final 6 years were compared for sensitivity to antibiotics and the proportion of MDR. MDR was defined as resistance to at least two different classes of antibiotics.

Results:

Pseudomonas accounted for 74 of 389 endophthalmitis cases (19%), 42 in initial 6 and 32 in final 6 years. Sensitivity to ciprofloxacin, ofloxacin, gatifloxacin, moxifloxacin, and ceftazidime was 85.7%, 82.9%, 76.5%, 76.9%, 88.1% up to 2010 which reduced to 75%, 59.4%, 68.8%, 56.3%, 56.3%, respectively, after 2010, being significant for ofloxacin (P = 0.0349) and ceftazidime (P = 0.0028). Susceptibility to amikacin, gentamicin, and tobramycin changed non-significantly from 83.3%, 43.9%, 47.6% to 71.9%, 61.3%, 61.3%, respectively. Twenty of 74 cases (27%) were MDR with 16.7% in first 6 years versus 40.6% in final 6 years. Postoperative MDR cases rose from 10.3% to 50% (P = 0.0048).

Conclusion:

This study shows rising resistance of Pseudomonas to fluoroquinolones, amikacin, and ceftazidime in endophthalmitis. MDR also showed an upward trend, particularly in postsurgical cases.

Prevalence and Possible Predictors of Drug-Resistant Pseudomonas aeruginosa in External Ocular Infections: A Single-Center, Retrospective, Cross-Sectional Study

Objective

Ocular infections due to multi-drug-resistant Pseudomonas aeruginosa (MDRP) have been reported in recent years. This study was undertaken to determine the culture-positivity rate of P. aeruginosa and drug resistance among patients with suspected external ocular infections and to predict systemic risk factors for drug resistance in P. aeruginosa.

Methods

This retrospective, single-center, cross-sectional study involved 781 consecutive patients who provided samples for aerobic culture to test for a suspected external ocular infection. DRP was defined as a strain resistant to one or two of three antibiotics, levofloxacin, gentamicin, and imipenem; MDRP was defined as that which was resistant to all three.

Results

Among 108 patients in whom gram-negative bacilli were observed, P. aeruginosa was isolated from nine patients, including three DRP-positive cases; no MDRP was isolated. P. aeruginosa was not isolated from those <69 years of age. Among patients in whom gram-negative bacilli were detected, the isolation rate of P. aeruginosa was 0 for patients aged ≤64 and 0.1 for those aged ≥65, indicating a significant difference. For patients with gram-negative bacilli, the DRP-positivity rate was significantly higher for hospitalized patients than outpatients. Thus, in addition to being geriatric, being hospitalized was a risk factor for DRP infection among patients with gram-negative bacilli. All the P. aeruginosa strains isolated were susceptible to colistin.

Conclusions

Our findings may suggest that once gram-negative bacilli are isolated in an elderly hospitalized patient, possible DRP infection and the topical use of colistin should be taken into consideration even before the results of culture and susceptibility testing are obtained.

Management of multi drug resistant endogenous Klebsiella pneumoniae endophthalmitis with intravitreal and systemic colistin

We report a case of a 35-year-old male with a pancreatic pseudocyst, who developed bilateral endogenous endophthalmitis, 4 days after surgical drainage of the pseudocyst. Bacterial cultures of the pancreatic drain fluid and the vitreous tap showed the growth of Klebsiella pneumoniae. The cultured organism was resistant to all the tested antibiotics except colistin. Intravenous colistin was instituted and three injections of intravitreal colistin were given in the left eye of the patient. Complete resolution of infection was seen and visual acuity of 6/6 was regained in both eyes, which was maintained at 4-month follow-up.