Clinical and bacteriological outcome of combined intravitreal injection of vancomycin and ceftazidime in experimentally induced endophthalmitis

Salah A Mady; Tarek N Attia; Tamer I Salem; Yasser Ismail; Asaad A Ghanem

doi:10.4103/1110-9173.189474

ORIGINAL ARTICLE

Year : 2016 | Volume : 17 | Issue : 2 | Page : 85-90

Clinical and bacteriological outcome of combined intravitreal injection of vancomycin and ceftazidime in experimentally induced endophthalmitis

Salah A Mady MD ¹, Tarek N Attia¹, Tamer I Salem¹, Yasser Ismail², Asaad A Ghanem³
¹ Ophthalmology Department, Faculty of Medicine, Banha University, Banha, Egypt
² Clinical Pathology Department, Faculty of Medicine, Banha University, Banha, Egypt
³ Mansoura Ophthalmic Center, Faculty of Medicine, Mansoura University, Mansoura, Egypt

Date of Submission	25-May-2015
Date of Acceptance	26-Aug-2015
Date of Web Publication	30-Aug-2016

Correspondence Address:
Salah A Mady
Ophthalmology Department, Faculty of Medicine, Banha University, Banha
Egypt

Source of Support: None, Conflict of Interest: None

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DOI: 10.4103/1110-9173.189474

Abstract

Introduction
Endophthalmitis, despite being rare, is the most serious complication of ocular surgery. Aminoglycosides, used in combination with vancomycin (VAN), were found to cause macular toxicity. Ceftazidime has been suggested as an alternative antibiotic because of its lower risk of retinal toxicity.
Purpose of the study
The purpose is to evaluate outcome of intravitreal injection (IVI) of VAN and ceftazidime combination versus ciprofloxacin on experimentally induced endophthalmitis.
Materials and methods
Twenty-one albino rabbits were divided into three groups as follows: group I received IVI of 0.1 ml saline, group II received IVI of VAN (1 mg/0.1 ml) and ceftazidime (2.25 mg/0.1 ml), and group III received IVI of ciprofloxacin (1 mg/0.1 ml). Right eyes were inoculated with 10⁵ colony forming units (CFU)/0.l ml of Staphylococcus epidermidis. After 24 h, inoculated eyes were examined by indirect ophthalmoscopy for signs and severity of endophthalmitis according to the modified scheme of Peyman and Bassili, and IVI was provided. On day 3 of the study, inoculated eyes were re-examined clinically, vitreous samples were obtained for bacteriological examination, and if culture was positive, antibiotics were reinjected. On day 6, animals were killed, right eyes were enucleated, and contents of the posterior segment were inoculated on blood agar for evaluation of bacterial growth and counting the CFU.
Results
On day 3, frequency of animals having severe grades of conjunctival injection and corneal edema was significantly higher in groups I and III compared with group II, and not significantly higher in group I compared with group III. Frequency of animals showing good red reflex was significantly higher in group II compared with groups I and III, and not significant different in group III compared with group I. On day 3, the mean number of CFU was significantly lower in group II compared with groups I and III with significantly lower number in group III compared with group I. On day 6, all samples of group II were sterile, while mean number of CFU was significantly lower in group III compared with group III.
Conclusion
Combined therapy using VAN and ceftazidime provided proper clinical and bacteriological control of experimentally induced endophthalmitis, with significant difference from single-drug therapy.

Keywords: ceftazidime, ciprofloxacin, endophthalmitis, experimental, intravitreal injection, vancomycin

How to cite this article:
Mady SA, Attia TN, Salem TI, Ismail Y, Ghanem AA. Clinical and bacteriological outcome of combined intravitreal injection of vancomycin and ceftazidime in experimentally induced endophthalmitis. Delta J Ophthalmol 2016;17:85-90

How to cite this URL:
Mady SA, Attia TN, Salem TI, Ismail Y, Ghanem AA. Clinical and bacteriological outcome of combined intravitreal injection of vancomycin and ceftazidime in experimentally induced endophthalmitis. Delta J Ophthalmol [serial online] 2016 [cited 2022 Aug 18];17:85-90. Available from: http://www.djo.eg.net/text.asp?2016/17/2/85/189474

Introduction

Endophthalmitis, despite being rare, is a potentially serious disease state. It is the most serious complication of ocular surgery and it may also arise after penetrating ocular trauma, or from systemic or periocular infection [1]. Within the literature, the incidence of endophthalmitis as postoperative complication varies substantially, ranging from 0% [2], to as high as 0.8% [3], and 1.24% [4]. Even with the best treatment, endophthalmitis can result in severe visual loss. Previous studies have reported final visual acuity of 20/400 or worse in up to 47% of patients, and that up to 25% of eyes required enucleation/evisceration [5],[6].

The source of microorganisms infecting the eye included the patient's own ocular surface flora, infection stemming from contaminated surgical instruments, surgical complications, poor or delayed wound healing, and patients presenting preoperatively with blepharitis and inflammation or infection of the eyelids. The majority of some bacteria organisms causing postoperative endophthalmitis are Gram-positive microbes including Staphylococcus epidermidis (coagulase-negative Staphylococci), Staphylococcus aureus (including methicillin-resistant strains), β-hemolytic Streptococci, and Enterococcus faecalis and Gram-negative rods including Haemophilus influenzae and Pseudomonas aeruginosa. Some of these microorganisms causing postoperative endophthalmitis could be multidrug resistant [7],[8].

Vancomycin (VAN) is a fermentation product of Amycolatopsis orientalis; an actinomycete. VAN is a glycopeptide that is highly effective against Gram-positive cocci. It is rapidly bactericidal for actively dividing organisms, inhibiting cell wall synthesis by binding with protein precursors of its structure. Essentially, all Gram-positive bacteria are sensitive to VAN, including Staphylococci, Streptococci, and Bacillus spp. [9].

Aminoglycosides (gentamycin or amikacin) have been used in combination with VAN; however, they were found to cause macular toxicity. Thus, ceftazidime, a third-generation cephalosporin, has been suggested as an alternative antibiotic because of its broad-therapeutic index, lower risk of retinal toxicity, and its in-vitro sensitivities that are as sensitive as the aminoglycosides. Intravitreal ceftazidime concentration after intravitreal injection (IVI) has half-life of about 7.4 h, but remained at a mean of 13 μg/ml, even 48 h after injection. This concentration exceeded the minimum inhibitory concentration of common Gram-positive and Gram-negative organisms causing endophthalmitis [10].

The current study aimed to evaluate the outcomes of IVI of VAN and ceftazidime combination and ciprofloxacin on experimentally induced endophthalmitis.

Materials and methods

Study design

This prospective comparative experimental study was conducted at the Ophthalmology and Clinical Pathology Departments, Faculty of Medicine, Banha University. The study protocol was approved by the Local Ethical Committee (Banha Faculty of Medicine), concerning animal model study.

Animals

The study included 21 New Zealand albino male rabbits weighing 1–1.5 kg. Animals were kept in separate animal cages, under standard conditions of temperature 20°C, humidity 60%, 12-h day/night cycle, and were maintained on a balanced diet and fresh-water supply. Animals were examined for clear anterior segment and intact red reflex with normal posterior segment by indirect ophthalmoscopy.

Preparation of injected solutions

The inoculum

A few S. epidermidis colonies (coagulase-negative) were transferred with a sterilized loop from the original fresh culture plate and were suspended in a tube containing 4 ml of sterile normal saline. The suspension was adjusted with sterile saline to achieve a concentration of 10⁵ colony forming units (CFU)/0.l ml S. epidermidis (as 0.5 McFarland).

Vancomycin

An aliquot distilled (10 ml) of sterile water was injected using sterile syringe into the vial containing 500 mg VAN in powdered form. Then, with a sterile syringe, 1 ml of this concentration was withdrawn and diluted with 4 ml sterile water to obtain a concentration of 1 mg/0.1 ml to be used for IVI.

Ceftazidime

An aliquot (10 ml) of sterile water was injected using sterile syringe into the vial containing 1000 mg ceftazidime in powdered form. Then, with a sterile syringe, 1 ml of this concentration (100 mg/ml) was withdrawn and diluted with 4.5 ml sterile water to obtain a concentration of 2.25 mg/0.1 ml to be used for IVI.

Ciprofloxacin

An aliquot (1 ml) of sterile ciprofloxacin infusion (200 mg/ml) was withdrawn using sterile syringe to be diluted with 1 ml of sterile water to obtain a concentration of 1 mg/0.1 ml to be used for IVI.

Groups and drugs

The animals studied were divided into three groups: group I included seven animals that received IVI of 0.1 ml saline. Group II included seven animals that received IVI of VAN (1 mg/0.1 ml) and ceftazidime (2.25 mg/0.1 ml) 24 h postinoculation. Physical incompatibility of the two antibiotics was avoided by injecting them slowly through different syringes. Group III included seven animals that received IVI of ciprofloxacin (1 mg/0.1 ml) 24 h postinoculation.

Study procedure

Day 0 (day of inoculation)

The right eye of each animal was used as the study eye, whereas the left eye served as an uninfected control for each animal. Topical anesthetic eye drops (benoxinate hydrochloride, available commercially as boxinate eye drops) was instilled into the right eye. Then, animals were tranquilized with intramuscular injection of mixture of ketamine (30 mg/kg) and xylocaine (10 mg/kg).

Using a sterile insulin syringe, 0.1 ml of aqueous humor was withdrawn through an anterior chamber paracentesis to prevent an increase in intraocular pressure. Another sterile insulin syringe was used for IVI of 10⁵ CFU/0.1 ml of S. epidermidis in the right eye of each animal, 3.5 mm posterior to the limbus going inside the globe into the middle of the vitreous cavity under direct visualization through the pupil.

Day 1 of the study (24 h after inoculation)

Inoculated eyes were examined by indirect ophthalmoscopy for the presence of signs of endophthalmitis and its severity was graded according to a modified scheme of Peyman and Bassili [11], as shown in [Table 1]. Eyes showing inflammatory signs were excluded from the study and animals were replaced to equalize the study groups. Intravitreal therapy was provided as previously described.

Table 1 Clinical grading of endophthalmitis [11]

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Day 3 of the study (48 h after antibiotics intravitreal injection)

By indirect ophthalmoscopy, right eyes were examined for the presence of signs of endophthalmitis and its severity was graded. Vitreous samples were obtained by vitreous tap using a 23-G 1-inch needle passed through the pars plana 3.5 mm posterior to the limbus into the anterior vitreous cavity. Needle tip was visualized through the pupil for adjusting its position and 0.2 ml of undiluted vitreous was withdrawn.

Vitreous samples were used for culture and calculation of the number of colonies and if culture was still positive, antibiotics were reinjected.

Day 6 of the study (48 h after intravitreal injection of the second dose of antibiotics)

All rabbits were killed and their right eyes were enucleated. In the microbiology laboratory, using a sterile scalpel, a puncture was made in the globe and all the contents of the posterior segment were evacuated in a sterile Petri dish ^{More Details}. Collected material was diluted in 1-ml broth and eight serial dilutions using sterile saline solution were prepared. An aliquot (1 ml) was taken from each dilution and inoculated on blood agar in a Petri plate labeled according to the dilution.

Plates were incubated at 37°C for 24 h. In plates with highest serial dilution, where there was growth, only discrete colonies of S. epidermidis were counted.

Results

Clinical outcomes at day 3 of the study

Right eyes of the studied animals were clinically examined for conjunctival injection (CI), corneal clarity, and red-reflex detection. Concerning CI, eight animals; five of group I and three of group III, showed CI of grade 3. Eight other animals; two of group I, two of group II, and four of group III, showed CI of grade 2. Two animals of group II showed CI of grade 1 and three of grade 0. The frequency of animals with severe grades of CI was significantly higher in groups I and III compared with group II, and not significantly higher in group I compared with group II [Table 2] and [Figure 1].

Table 2 Clinical outcome of studied animals on day 3 of the study (at 48 h after intravenous injection of antibiotics)

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Figure 1 Animals’ distribution according to conjunctival injection grading at 48 h after intravenous injection (IVI) of antibiotics.

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Only four animals in group II showed no corneal edema on clinical examination at 48 h after IVI of antibiotics. Seven animals; one in group I and three in each of groups II and III showed corneal edema of grade 1. Four animals; two in each of groups I and III showed corneal edema of grade 2. Six animals; four in group I and two in group III showed corneal edema of grade 3. The frequency of animals among severe corneal edema was significantly higher in groups I and III compared with group II, and not significantly higher in group I compared with group II [Table 2] and [Figure 2].

Figure 2 Animals’ distribution according to corneal edema grading at 48 h after intravenous injection (IVI) of antibiotics.

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Only four animals in group II showed grade 1 red-reflex detection on clinical examination at 48 h after IVI of antibiotics. Nine animals; two in group I, three in group II, and four in group III showed grade 2 red-reflex detection. Seven animals; five in group I and two in group III showed grade 3 red-reflex detection. The frequency of animals showing good red reflex was significantly higher in group II compared with groups I and II, and not significantly higher in group II compared with group I [Table 2] and [Figure 3].

Figure 3 Animals’ distribution according to grading of red-reflex detection at 48 h after intravenous injection (IVI) of antibiotics.

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Bacteriological outcomes

At day 3 of the study, the mean number of CFU detected on the bacteriological culture of vitreous samples were 3.31 × 10⁷ CFU for group I [Figure 4]a), 0.51 × 10² CFU for group II [Figure 4]b), and 2 × 10⁵ CFU for group III [Figure 4]c).

Figure 4 (a) Blood culture at day 3 of the study in group I. (b) Blood culture at day 3 of the study in group II. (c) Blood culture at day 3 of the study in group III.

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At day 3 of the study, the mean number of CFU detected on the bacteriological culture of vitreous samples were 5.7 × 10¹¹ CFU for group I [Figure 5]a), 0 CFU for group II [Figure 5]b), and 4.7 × 10² CFU for group III [Figure 5]c). The mean number of CFU was significantly higher in group I compared with group III.

Figure 5 (a) Blood culture at day 6 of the study in group I. (b) Blood culture at day 6 of the study in group II. (c) Blood culture at day 6 of the study in group III.

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Discussion

Intravitreal antibiotic therapy, irrespective of its composition or being given single or in combination, could effectively control endophthalmitis manifested as improved clinical scoring and bacteriological findings. In line with this finding, Liu et al.[12], in rabbit model of endophthalmitis, found that IVI of VAN improved the therapeutic outcomes of Bacillus cereus endophthalmitis. Wiskur et al.[13], in rabbit model, reported that early IVI of VAN or gatifloxacin improved the therapeutic outcomes of B. cereus endophthalmitis, and the addition of dexamethasone to antibiotic treatment did not provide a therapeutic benefit over antibiotics alone and appeared to reduce the antibiotic efficacy of VAN 6 h after injection. Sakalar et al.[14], found that intravitreal moxifloxacin injection is effective in experimental B. cereus endophthalmitis, and the addition of intravitreal dexamethasone may not significantly affect treatment efficacy.

Saleh et al.[15] found linezolid to be as effective as VAN for treatment of experimental Staphylococcal endophthalmitis, but displayed a concentration-dependent killing activity in the eye and high ocular concentrations were needed to obtain a satisfactory bactericidal effect. Nagaraj and Jayadev [16] presented a case of 65-year-old man, who presented with decreased vision in the left eye of 15-day duration after having undergone an uneventful cataract surgery 10 months back, aqueous tap revealed P. aeruginosa sensitive to ciprofloxacin and gave good clinical response on intravitreal ciprofloxacin and VAN along with systemic ciprofloxacin.

Coskun et al.[17] experimentally found that the mean number of CFU and histopathological scores were significantly lower in daptomycin and VAN groups compared with control group, with no difference between both treatment groups in terms of the histopathological and clinical examination scores. Ozcimen et al.[18] compared bactericidal activities of daptomycin and VAN in an experimental rabbit model of E. faecalis endophthalmitis and found no difference between both drugs in terms of the histopathological and clinical examination scores and bacterial counts and on day 4, 62 and 50% of the eyes treated with both drugs, respectively, were sterilized.

However, the applied antibiotic combination of VAN and ceftazidime provided marvelous effect manifested both clinically and bacteriologically compared with the use of single antibiotic, where blood culture of extracted posterior chamber material at the end of the study, at 48 h after second IVI of antibiotics.

In line with combined intravitreal therapy, Ferrer et al.[19] compared levofloxacin with a combination of VAN and ceftazidime for S. epidermidis endophthalmitis model and found levofloxacin treatment produced an ∼3 log decrease in CFU/ml of vitreous relative to that in untreated eyes, whereas VAN plus ceftazidime produced a 5 log reduction in CFU/ml. Pijl et al.[20] clinically studied 250 cases of acute postcataract endophthalmitis using vitreous biopsy with an IVI of VAN and ceftazidime with or without prednisolone in 225 cases and primary vitrectomy with intravitreal antibiotics in 25 eyes and reported improved final visual acuity in 51.6% of all cases, but found no additional effect for treatment by primary vitrectomy or intravitreal prednisolone.

Conclusion

Combined therapy using VAN and ceftazidime provided proper clinical and bacteriological control of experimentally induced endophthalmitis with a significant difference compared with single drug therapy.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

References

1.	O’Brien TP, Arshinoff SA, Mah FS. Perspectives on antibiotics for postoperative endophthalmitis prophylaxis: potential role of moxifloxacin. J Cataract Refract Surg 2007; 33:1790–1800.
2.	Friling E, Lundström M, Stenevi U, Montan P. Six-year incidence of endophthalmitis after cataract surgery: Swedish National Study. J Cataract Refract Surg 2013; 39:15–21.
3.	Francis IC, Roufas A, Figueira EC, Pandya VB, Bhardwaj G, Chui J. Endophthalmitis following cataract surgery: the sucking corneal wound. J Cataract Refract Surg 2009; 35:1643–1645.
4.	Barreau G, Mounier M, Marin B, Adenis JP, Robert PY. Intracameral cefuroxime injection at the end of cataract surgery to reduce the incidence of endophthalmitis: French study. J Cataract Refract Surg 2012; 38:1370–1375.
5.	Al-Mezaine HS, Kangave D, Al-Assiri A, Al-Rajhi AA. Acute-onset nosocomial endophthalmitis after cataract surgery: incidence, clinical features, causative organisms, and visual outcomes. J Cataract Refract Surg 2009; 35:643–649.
6.	Ding Y, Lin M, Liu H, Zhang W, Wang L, Li Y. Outcomes of post-cataract surgery endophthalmitis referred to a tertiary center from local hospitals in the south of China. Infection 2011; 39:451–460.
7.	Barry P, Behrens Baumann W, Pleye U, Seal D. ESCRS guidelines on prevention, investigation and management of postoperative endophthalmitis, version 2. Dublin, Ireland, The European Society for Cataract and Refractive Surgeons 2007; Available at: http://www.chulaophthalmology.org/userfiles/download/ESCRS_Guidelines_2007.pdf. [Accessed 10 March 2015].
8.	ESCRS guidelines on prevention and treatment of endophthalmitis following cataract surgery. The European Society for Cataract and Refractive Surgeons 2013; Available at: http://www.escrs.org/endophthalmitis/guidelines/ENGLISH.pdf. [Accessed 15 January 2014].
9.	Liu C, Bayer A, Cosgrove SE, Daum RS, Fridkin SK, Gorwitz RJ et al. Clinical practice guidelines by the Infectious Diseases Society of America for the treatment of methicillin-resistant Staphylococcus aureus infections in adults and children. Clin Infect Dis 2011; 52:e18–e55.
10.	Penha FM, Rodrigues EB, Maia M, Furlani BA, Regatieri C, Melo GB et al. Retinal and ocular toxicity in ocular application of drugs and chemicals–part II: retinal toxicity of current and new drugs. Ophthalmic Res 2010; 44:205–224.
11.	Peyman GA, Bassili SS. A practical guideline for management of endophthalmitis. Ophthalmic Surg 1995; 26:294–303.
12.	Liu F, Kwok AK, Cheung BM. The efficacy of intravitreal vancomycin and dexamethasone in the treatment of experimental bacillus cereus endophthalmitis. Curr Eye Res 2008; 33:761–768.
13.	Wiskur BJ, Robinson ML, Farrand AJ, Novosad BD, Callegan MC et al. Robinson ML Farrand AJ, et al. Toward improving therapeutic regimens for Bacillus endophthalmitis. Invest Ophthalmol Vis Sci 2008; 49:1480–1487.
14.	Sakalar YB, Ozekinci S, Celen MK. Treatment of experimental Bacillus cereus endophthalmitis using intravitreal moxifloxacin with or without dexamethasone. J Ocul Pharmacol Ther 2011; 27:593–598.
15.	Saleh M, Lefèvre S, Acar N, Bourcier T, Marcellin L, Prévost G et al. Efficacy of intravitreal administrations of linezolid in an experimental model of S. aureus-related endophthalmitis. Invest Ophthalmol Vis Sci 2012; 53:4832–4841.
16.	Nagaraj KB, Jayadev C. Pseudomonas aeruginosa endophthalmitis masquerading as chronic uveitis. Indian J Ophthalmol 2013; 61:309–310. [PUBMED]
17.	Coskun E, Okumus S, Gurler B, Demir T, Bahar AY, Zer Y. Comparison of intravitreal vancomycin and daptomycin application in experimental methicillin-resistant Staphylococcus aureus (MRSA) endophthalmitis in rabbits. Cutan Ocul Toxicol 2013; 32:222–227.
18.	Ozcimen M, Kurtoglu MG, Goktas S, Omeroglu E, Sakarya Y, Alpfidan I. Daptomycin versus vancomycin in an Enterococcus faecalis endophthalmitis rabbit model. Curr Eye Res 2015; 6:1–8.
19.	Ferrer C, Rodríguez A, Abad JL, Fernandez J, Alió JL. Bactericidal effect of intravitreal levofloxacin in an experimental model of endophthalmitis. Br J Ophthalmol 2008; 92:678–682.
20.	Pijl BJ, Theelen T, Tilanus MA, Rentenaar R, Crama N. Acute endophthalmitis after cataract surgery: 250 consecutive cases treated at a tertiary referral center in the Netherlands. Am J Ophthalmol 2010; 149:482–487.