·Clinical Research·
Ocular
flora in patients undergoing intravitreal injections: antibiotic resistance
patterns and susceptibility to antiseptic picloxydine
Maria
V. Budzinskaya1, Anait S. Khalatyan1, Marina G.
Strakhovskaya2,3, Vladimir G. Zhukhovitsky4
1Scientific
Research Institute of Eye Diseases, Moscow 119021, Russia
2Department
of Biology, Lomonosov Moscow State University, Moscow 119234, Russia
3Federal
Research and Clinical Center of Specialized Medical Care and Medical
Technologies, Federal Medical and Biological Agency of Russia, Moscow 115682,
Russia
4Gamaleya
National Research Centre for Epidemiology and Microbiology, Moscow 123098,
Russia
Correspondence
to: Anait S.
Khalatyan. Scientific Research Institute of Eye Diseases, Klimashkina street
19-30, Moscow 123557, Russia. anaits92@gmail.com
Received:
Abstract
AIM: To study antibiotic
resistance patterns and susceptibility to eye antiseptic picloxydine of
conjunctival flora in patients undergoing intravitreal injections (IVIs).
METHODS: Conjunctival swabs
were taken in 4 groups of patients, 20 patients in each group (n=80):
without IVIs and ophthalmic operations in history (group N1; control group);
with the first IVI and antibiotic eye drops Tobrex applied 3d before IVI and 5d
after it (group N2); with 20 or more IVIs and repeated courses of antibiotic
eye drops (group N3); with the first IVI and antiseptic eye drops Vitabact
(picloxydine) applied 3d before IVI and 5d after it (group N4). In groups N2
and N4 swabs were taken at baseline and after the treatment. Efficacy of
picloxydine in inhibition of growth of conjunctival isolates susceptible and
resistant to antibiotic was studied in vitro. Minimal inhibition
concentrations (MIC) were determined with microdilution test.
RESULTS: Two of the three
patients who had to undergo the IVI procedure showed conjunctiva bacterial
contamination. Along with few Staphylococcus aureus and Gram-negative
isolates susceptible to most antibiotics, the majority (71%-77%) of causative
agents were coagulase-negative Staphylococci (CoNS), 40%-50% of which
were multidrug resistant (MDR). Eye disinfection in the operating room and
peri-injection courses of Tobrex or Vitabact resulted in total elimination of
isolates found at baseline. However, in 10% and 20% of patients, respectively,
recolonization of the conjunctiva with differing strains occurred. In patients
with repeated IVI and Tobrex/Maxitrol treatment, the conjunctival flora showed
high resistance rates: 90% of CoNS were MDR. In the in vitro study,
picloxydine showed bactericidal effect against Staphylococci isolates
both antibiotic resistant and susceptible with MIC≥13.56 µg/mL. Incubation of
bacteria for 15min in Vitabact eye drops, commercially available form of
picloxydine, 434 µg/mL, showed total loss of colony forming units of all tested
isolates including Pseudomonas aeruginosa.
CONCLUSION: The confirmed efficacy
of eye antiseptic picloxydine against conjunctival bacterial isolates and the
presence of its commercial form, 0.05% eye drops, convenient for use by
patients before and after injection, make this eye antiseptic promising for
prophylaxis of IVI-associated infectious complications.
KEYWORDS: intravitreal
injections; conjunctival isolates; antibiotic resistance; picloxydine; Vitabact
DOI:10.18240/ijo.2020.01.13
Citation:
Budzinskaya MV, Khalatyan AS, Strakhovskaya MG, Zhukhovitsky VG. Ocular flora
in patients undergoing intravitreal injections: antibiotic resistance patterns
and susceptibility to antiseptic picloxydine. Int J Ophthalmol 2020;13(1):85-92
INTRODUCTION
Intravitreal injections (IVIs) are
one of the effective, widespread and minimally invasive methods of treatment of
various retinal diseases. The effectiveness of such therapy is observed in the
treatment of exudative age-related macular degeneration, edema, associated with
diabetic retinopathy or retinal vein occlusions. Due to a noticeable increase
in the incidence of diabetes mellitus and cardiovascular diseases it is
expected that the number of IVIs will steadily continue to rise. Generally, IVI
is a safe procedure. However, like any surgical intervention, it carries the
risk of potential complications. Infectious complications, associated with
IVIs, occur when a pathogen from the eye surface in the site of the injection
penetrates the vitreous cavity. The most dangerous complication is the
infectious endophthalmitis with visual impairment threat even in a case of
proper and early treatment[1-2].
The importance of antimicrobial
treatment accompanying the IVI procedure is obvious. However, to date, there is
no single approach to the management of patients regarding the use of
antibacterial eye drops before and/or after IVI as a prevention method of
inflammatory infectious complications. In 2004 when the practice of IVI was
just introduced, ophthalmic antibiotics were widely used for this purpose[3]. But unlike other ocular surgeries, conducted once or
twice in a patient’s life, where topical antibiotics may be an appropriate
prophylactic measure, IVIs are often repeated to the same eye[4].
In such patients, short-term repeated courses of topical antibiotics
accompanying IVI may not only reduce the risk of infectious complications but
actually enhance it by increasing antibiotic resistance of conjunctival flora.
In recent years, this has been confirmed in several studies.
Coagulase-negative staphylococci
(CoNS), the most common bacteria on the eye surface[5],
demonstrated increased rates of resistance to fluoroquinolones if isolated from
eyes repeatedly exposed to one of the following ophthalmic antibiotics ofloxacin/gatifloxacin/moxifloxacin
hydrochloride[6]. As shown in the study[7], CoNS isolates from azithromycin-exposed eyes were
characterized by increased macrolide resistance. The predominant CoNS strain Staphylococcus
epidermidis (S. epidermidis) developed co-resistance to
trimethoprim/sulfamethoxazole, gentamicin and clindamycin in
fluoroquinolone-exposed eyes and to trimethoprim/sulfamethoxazole and
doxycycline in azithromycin-exposed eyes[7].
Milder et al[8] and Dorrepaal et al[9] also found the increased antibiotic resistance of
conjunctival flora due to repeated use of fluoroquinolone drops. The selection
of resistant bacteria does not require so much time. Thus, bacterial colonies
with high resistance to gatifloxacin were isolated from the eye of the patient
who received only three IVIs with a prophylactic use of this topical antibiotic[9].
Along with the increased resistance,
repeated courses of topical eye antibiotics cause changes in the composition of
conjunctival flora with the significant increase in the percentage of S.
epidermidis[10]. The authors note the
clinical significance of this fact because S. epidermidis is the main
causative agent of ocular infections.
Grzybowski et al[5] consider IVI to be “a prime example where unnecessary
and/or improper use of antibiotics may have serious consequences”. An
alternative may be the use of antiseptics with efficacy comparable to
antibiotics such as povidone-iodine or biguanides. Barkana et al[11] proved that there was no significant difference
between povidone-iodine, chlorhexidine (cationic biguanide) and ofloxacin in
terms of reduction of conjunctival flora, 91.2%, 87.6% and 85.6%, respectively.
Merani et al[12] showed that aqueous
chlorhexidine used as an antiseptic drug before IVI was well tolerated and
effective in terms of low rate of endophthalmitis. In conjunctival samples
after the treatment with chlorhexidine 0.05%, there was a significant reduction
in the total bacterial load (82%) and even greater results were observed for
CoNS (90%). In this study by Gili et al[13],
no povidone-iodine was administered to the patient, eye irrigation was
performed only using 0.05% chlorhexidine solution.
When comparing povidone-iodine and
chlorhexidine, the former is still considered to be the gold standard for prophylaxis
of infectious complications in eye surgery[12].
Along with efficacy, application of brown colored povidone-iodine, in contrast
to colorless chlorhexidine, is easier for surgeon due to the visible areas of
irrigation. However, povidone-iodine has its deficiencies. There is a cohort of
patients with povidone sensitivity, not true immunoglobulin E-mediated allergy[14]. Sensitivity can be expressed in conjunctival
hyperemia, irritation (mild to severe) and pain. In these cases, surgeon should
consider using another antiseptic drug, for example, chlorhexidine. Thus,
Oakley and Vote[15] switched povidone-iodine to
0.1% chlorhexidine solution in patients reporting high levels of pain. As the
result, the average pain score decreased from 8 of 10 points to 3 of 10.
Another antiseptic from the group of biguanides is
picloxydine dihydrochloride commercially available as Vitabact, 0.05%.
Different pharmaceuticals companies worldwide produce eye drops of picloxydine
with different brand names: Vitabact (LaboratoiresThéa, France; Ciba Vision,
Lithuania; Novartis, Tunisia; Novartis, Excelvision, O.C.A. Vietnam), Medibact
(Medipak, Pakistan), Bactavit (Rompharm, Georgia). These approved eye drops
could be useful in pre- and post-injection prophylaxis of eye infections.
However, we found no data on the use of Vitabact in the management of patients
with IVI.
In the study, we confirmed the
increased resistance of conjunctival flora in patients with multiple IVIs and
antibiotic eye drops courses in anamnesis. We compared efficacy of antiseptic
Vitabact and antibiotic Tobrex eye drops in the eye surface decontamination. In
the in vitro experiments, we proved the bactericidal effect of Vitabact
eye drops against both antibiotic susceptible and resistant conjunctival bacterial
isolates.
SUBJECTS AND METHODS
Ethical Approval
This study was conducted in
accordance with the Declaration of Helsinki. All patients were recruited from
the Scientific Research Institute of Eye Diseases in Moscow, Russia. The local
biomedical ethics committee of the Scientific Research Institute of Eye
Diseases approved the protocol (protocol No.49/4). Informed written consent was
obtained from each patient before participation in the study.
This was a prospective case-control
study comparing 4 groups of patients, 20 patients in each group (n=80):
1) patients of the control group, comparable in age, without IVI and ophthalmic
operations in history (group N1); 2) patients undergoing the first IVI who
applied antibiotic eye drops Tobrex based on aminoglycoside tobramycin 3d
before IVI and within 5d after it (group N2); 3) patients who received 20 or
more IVIs and the concomitant courses of antibiotic eye drops Tobrex, in some
courses it was replaced by Maxitrol containing aminoglycoside neomycin, polymyxin
B and dexamethasone (group N3); 4) patients undergoing the first IVI who
applied antibacterial eye drops Vitabact (picloxydine) 3d before IVI and within
5d after it (group N4).
Exclusion criteria for all groups
were the following: age less than 50 years old, use of systemic antibiotics
within 3mo, use of ocular hypotensive drops for the management of glaucoma;
moreover, use of antibiotic drops and ocular surgery were exclusion criteria
for the second, third and fourth groups.
In the standard IVI procedure, the
eyelid skin and the area around the eye were treated with a 10% solution of
iodopyrone. Next, eyelid speculum was applied. Local anesthetic drops of
Alcaine were instilled in the conjunctival sac. The conjunctival cavity was
irrigated for 30s with 2.0 mL of 5% povidone-iodine and then with saline
solution to wash away povidone residue.
Conjunctival swabs were taken with
sterile disposable tampons using a standard procedure (from lateral to medial
angle of the eye) in the lower conjunctival fornix to the Amies transport
system, which maintains the viability of microorganisms from the time of the
material collection to the beginning of the study. Care was taken to minimize
the contact with lashes, eyelids and skin. In groups N2 and N4, conjunctival swabs
were taken both before (at baseline) and the next day after the end of
post-injection treatment with Tobrex or Vitabact.
In positive swabs, the isolated
microorganisms were identified and tested for antibiotic susceptibility by BD
Phoenix 100 automated identification and susceptibility testing system.
The in vitro inhibitory
effects of picloxydine in the form of commercially available eye drops
Vitabacton the growth of conjunctival isolates was analyzed with the broth
microdilution test. The Trypticase Soy Broth (Becton Dickinson, France)
containing a series of double-diluted Vitabact in the range 1:2 to 1:32
(corresponded to picloxydine 217.00 to 13.56 µg/mL) or without Vitabact in
control samples was used for bacterial growth. Three colonies of each isolate
grown for 24h at
Also, we assessed the pain score
after the procedure of IVI and after the treatment with Tobrexor Vitabact by
using the numeric pain rating scale (NPRS).
Statistical analysis was conducted with SPSS via contrasting
the respective 95% and 99% confidence intervals (based on the estimates of
group means and standard deviations). Pearson’s Chi-square test was used for
testing relationships between categorical variables. McNemar Chi-square test
was used on paired nominal data. It was applied to 2×2 contingency tables
with a dichotomous trait, with matched pairs of subjects, to determine whether
the row and column marginal frequencies are equal (e.g. to determine whether
particular microorganisms are found before and after the treatment). To compare
mean antibiotic resistance in various isolates at 0, 24 and 96h two-way ANOVA
with Tukey post-hoc test was used [separately for the condition without
Vitabact and for the condition with Vitabact (1:32 dilution)].
RESULTS
Ocular Flora and Antibiotic
Resistance Patterns A total of 120 conjunctival swabs from 80 eyes were collected during the
study. Of these 120 swabs, 59 isolates were cultured. S. epidermidis
composed the body (66.1%, 39/59) of isolates, followed by Staphylococcus
aureus (S. aureus; 11.86%, 7/59), Staphylococcus hominis (S.
hominis; 6.78%, 4/59), Staphylococcus haemolyticus (S.
haemolyticus; 5.08%, 3/59). Also, one isolate (1.69%, 1/59) of each was obtained:
Staphylococcus caprae (S. caprae), Staphylococcus lugdunensis (S.
lugdunensis), and Gram-negative microorganisms–Enterococcus cloacae,
Escherichia coli (E. coli), Pseudomonas auruginosa (P.
aeruginosa) and Pseudomonas luteola (P. luteola).
In the control group N1 (20 eyes),
microflora growth was detected in 14 swabs (70%). All the 14 isolates (Table 1)
were Gram-positive staphylococci: S. epidermidis was found in swabs of
11 patients (78.57%, 11/14), the rest 3 bacteria were S. caprae, S.
hominis and S. aureus, each 7.14% (1/14). Thus, 13 out of 14
(92.86%) isolates were CoNS. Among 13 CoNS, 6 isolates were resistant to drugs
of 3 to 4 antibiotics classes that is they are multidrug resistant (MDR).
Methicillin-resistant staphylococci (MRS) made up 30.77% (4/13) of CoNS
isolates (Figure 1). Almost the third of the isolates (30.77%, 4/13) were
resistant to gentamicin and tobramycin. Rather high percentage (23.08%, 3/13)
of CoNS were resistant to erythromycin or ciprofloxacin. The S. aureus
isolate was susceptible to all drugs among 21 tested except chloramphenicol.
Table 1 Bacterial species isolated
from conjunctival swabs in different groups of patients
n (%)
|
Bacterial species |
Control group N1 |
Group N2 |
Group N3 after multiple IVIs and antibiotic eye
drops treatments |
|
|
Before the first IVI and antibiotic eye drops
treatment |
After the first IVI and antibiotic eye drops
treatment |
|||
|
Gram-positive |
14 (100) |
13 (92.9) |
2 (100) |
11 (91.7) |
|
S. epidermidis |
11 (78.6) |
7 (50.0) |
- |
8 (66.7) |
|
S. caprae |
1 (7.14) |
- |
- |
- |
|
S. haemolyticus |
- |
1 (7.14) |
- |
2 (16.7) |
|
S. hominis |
1 (7.14) |
2 (14.3) |
1 (50.0) |
- |
|
S. lugdunensis |
- |
- |
1 (50.0) |
- |
|
S. aureus |
1 (7.14) |
3 (21.4) |
|
1 (8.3) |
|
Gram-negative |
0 |
1 (7.14) |
0 |
1 (8.3) |
|
Enterobacter cloacae |
- |
1 (7.14) |
- |
- |
|
P.
aeruginosa |
- |
- |
- |
1 (8.3) |
Figure 1 Percentage of antibiotic
resistant coagulase-negative Staphylococcus spp. (CoNS) isolates in
different groups of patients.
In the group of 20 patients who had
to undergo the first IVI and antibiotic eye drops Tobrex treatment (group N2),
the swabs were obtained before (20 eyes) and after (20 eyes) this treatment.
Like in the control group, at baseline before the treatment microflora growth
was observed in 14 swabs (70%, 14/20). The isolates represented different types
of staphylococci, including 10 CoNS (76.92%, 10/13) and 3 S. aureus
(23.08%, 3/13). Among 10 CoNS, 5 (50%) were MDR and 3 (30%) MRS, 2 (20%) were
gentamicin and tobramycin and 2 (20%) ciprofloxacin resistant (Figure 1). This
corresponded to the control group in Gram-positive/Gram-negative proportion
(Pearson’s χ2=1.04, P=0.31) as well as in
bacterial species’ structure (Pearson’s χ2=5.22, P=0.63). Actually, all three groups (N1, N2 before the
treatment, and N3) were equivalent in Gram-positive/Gram-negative proportion
(Pearson’s χ2=1.15, P=0.56) as well as in
bacterial species’ structure (Pearson’s χ2=12.47, P=0.41. Surprisingly, in this group of patients who had to
undergo the first IVI, the percentage of erythromycin resistant CoNS reached
70% (7/10) that was much higher as compared with the control group (Figure 1).
As for S. aureus isolates, the first one was antibiotic susceptible, the
second was resistant to penicillin G and the third to tobramycin and
tetracycline. In one case, Gram negative Enterobacter cloacae was
isolated (Table 1).
In the same group N2 of 20 patients
after the first IVI procedure and peri-injection treatment with Tobrex (20
eyes), only two conjunctival swabs were positive. These changes were
statistically significant (McNemar χ2=6.75, P=0.009). In one patient, no growth was observed in swabs
taken at the first visit, and after the IVI and Tobrex treatment, antibiotic
susceptible S. hominis was isolated. In the swabs of the second patient S.
haemolyticus resistant to erythromycin, chloramphenicol and fosfomycin
(including glucose-6-phosphate) was isolated at the first visit, and S.
lugdunensis resistant to fosfomycin was obtained at the second visit.
In 20 patients (20 eyes) who
received 20 IVIs and peri-injection prophylaxis with antibiotic eye drops
(group N3), 11 swabs were positive (55%, 11/20), one of them gave the growth of
two isolates (S. epidermidis and S. haemolyticus). Eleven
cultures were staphylococci (Table 1), among them ten were CoNS, 80% (8/10) S.
epidermidis and 20% (2/10) S. haemoyticus. The rest one was S.
aureus. In addition, Gram negative P. aeruginosa was detected in one
case. As for antibiotic patterns, the conjunctival flora in such patients was
characterized by an increase in the number of strains resistant to a wide range
of antibiotics. Nine of ten CoNS were MDR (90%). Among these, we found S.
epidermidis isolate resistant to 11 antibiotic classes. In this group of
patients who received repeated courses of aminoglycoside-containing eye drops
Tobrex/Maxitrol, 90% (9/10) CoNS and the single isolate of S. aureus
were gentamicin and tobramycin resistant (Figure 1). This threatening situation
encouraged us to try antiseptic picloxydine-containing eye drops Vitabact in
peri-injection antimicrobial prophylaxis.
In group N4 of 20 patients who were
prescribed antiseptic eye drops Vitabact 3d before the first IVI (20 eyes) and
within 5d after it (20 eyes), microflora growth was not detected in 80% of
swabs taken next day after the end of the treatment. The swabs of 6 (30%, 6/20)
patients were negative at baseline and after the treatment. From 13 positive
baseline swabs (65%, 13/20), the majority, namely 12 swabs (92.31%, 12/13)
showed Staphylococci growth. Ten CoNS isolates were represented by S.
epidermidis (Table 2). Out of ten, four S. epidermidis isolates were
MDR (40%, 4/10). Both S. aureus isolates were resistant to penicillin G
and one of them to ampicillin. In one case the rare P. luteola was
isolated. The latter was susceptible to all antibiotics tested.
Table 2 Bacterial species isolated
from conjunctival swabs in group of patients with the first IVI and Vitabact
treatment 3d before and 5d after it
n (%)
|
Bacterial species |
Before the treatment |
After the treatment |
McNemar χ2/P |
|
Gram-positive |
12 (92.3) |
3 (75.0) |
7.11/0.008 |
|
S. epidermidis |
10 (76.9) |
3 (75.0) |
5.14/0.023 |
|
S. aureus |
2 (15.4) |
- |
- |
|
Gram-negative |
1 (7.7) |
1 (25.0) |
- |
|
P. luteola |
1 (7.7) |
- |
- |
|
E. coli |
- |
1 (25.0) |
- |
After IVI and prophylaxis with
Vitabact the swabs of ten of these patients were negative. In three patients
(15%, 3/20), S. epidermidis growth was observed both before and after
post-injection treatment with Vitabact. However, the cultures isolated before
and after the treatment differed in their resistance to certain antibiotics;
this fact indicates the elimination of the primary isolated strain as a result
of the Vitabact treatment and secondary infection with another strain of S.
epidermidis. In one patient (5%, 1/20), swab was negative before the
treatment, but after the treatment antibiotic-susceptible E. coli was
isolated, which can also be explained by secondary infection due to eye hygiene
breaches.
Conjunctival isolates Growth
Inhibition with Picloxydine Picloxydine (Vitabact) efficacy in
inhibition of conjunctival isolates growth was confirmed in the in vitro
study. In these experiments we analyzed the growth of 44 staphylococci isolates
in picloxydine-containing nutrient broth.These isolates included 5 S. aureus
(1 antibiotic susceptible, 4 resistant to 1-2 antibiotic classes), 33 S.
epidermidis (2 antibiotic susceptible, 15 resistant to 1-2 antibiotic
classes and 16 MDR), 2 S. haemolyticus (1 resistant to 2 antibiotic
classes and 1 MDR), 3 S. hominis (1 susceptible and 2 MDR), 1 S.
caprae (MDR). Three Gram-negative isolates were also included in the study:
P. aeruginosa, P. luteola and E. coli.
After 24h, we did not detect growth
of any staphylococci in series of liquid growth media containing double-diluted
Vitabact (from 1:2 to 1:32) that corresponded to decrease in picloxydine
concentration from 217.00 to 13.56 µg/mL for every condition (F=0.69; P=0.60).
Control suspensions without Vitabact showed equal bacteria growth in each of
three conditions, as observed by absorbance increase (F=0.77; P=0.55).
In Table 3 we summarized the growth parameters of staphylococci isolates in
nutrient broth without addition or in the presence of Vitabact in its lowest
concentration (1:32 dilution) tested in our study. In order to identify
possible differences in the Vitabact effect on MDR strains, CoNS that made up
the most of isolates were grouped according to their antibiotic resistance. S.
aureus formed one group, as among the few S. aureus MDR strains were
not isolated. We found no differences in picloxydine inhibitory effect on the
growth of isolates, MDR or bacteria resistant to no more than two drugs, as
well as CoNS and S. aureus.
Table 3 Absorbance of Staphylococci
cultures in nutrient broth growing without addition or with Vitabact (1:32
dilution) that corresponds to 13.56 µg/mL of picloxydine
mean±SD
|
Isolates |
Antibiotic resistance |
Growth time without Vitabact, h |
Growth time with Vitabact, h |
||||
|
0 |
24 |
96 |
0 |
24 |
96 |
||
|
S. aureus |
Susceptible or resistant to 1-2 drugs (n=5)a |
0.106±0.003 |
0.857±0.121 |
0.745±0.160 |
0.106±0.002 |
0.116±0.012 |
0.099±0.008 |
|
CoNS |
Susceptible or resistant to 1-2 drugs (n=19)a |
0.106±0.002 |
0.723±0.142 |
0.603±0.174 |
0.108±0.004 |
0.111±0.011 |
0.104±0.010 |
|
MDR (n=20)a |
0.107±0.002 |
0.712±0.189 |
0.667±0.223 |
0.105±0.006 |
0.119±0.013 |
0.114±0.034 |
|
CoNS: Coagulase-negative
staphylococci; MDR: Multidrug resistant; anumber of isolates.
As Tukey post-hoc test showed, after
96h growth the absorbance changes were insignificant as compared with 24h for
growth without Vitabact (P=0.92 for S. aureus, P=0.28 for
CoNS, P=0.84 for MDR) and for growth with Vitabact (P=0.63 for S.
aureus, P=0.79 for CoNS, P=0.90 for MDR). Only one isolate, S.
epidermidis resistant to clindamycin, chloramphenicol and erythromycin,
showed the growth of absorbance to the value of about 0.25. Its contribution in
the average MDR group absorbance after 96h growth is seen from increased
standard deviation (Table 3). The results again did not reveal a difference
depending on antibiotic sensitivity and staphylococci species (Vitabact effect
was statistically strong in all isolates at 1% level). The difference between 0
and 24h without Vitabactwas statistically significant for S.aureus
(Tukey post-hoc test, P=0.0001), for CoNS (Tukey post-hoc test, P=0.0001),
and for MDR (Tukey post-hoc test, P=0.0001).
Probes of each staphylococci culture
grown in nutrient broth for 24 or 96h with or without Vitabact dilutions were
cultivated further on agar plates within 24h. Those taken from
picloxydine-containing liquid media samples showed no growth except one
mentioned isolate with the lowest picloxydine concentration tested (13.56 µg/mL).
The picloxydine minimal inhibitory concentration (MIC) for staphylococci
conjunctival isolates growth was ≥13.56 µg/mL.
Among the Gram-negative bacteria,
the most resistant was P. aeruginosa isolate. It grew in liquid medium
even with 217.00 µg/mL picloxydine content (1:2 deluted Vitabact). For E.coli
and P. luteola the minimal picloxydine concentrations that inhibited the
growth of these isolates for 24h were 54.25 and 13.56 µg/mL, respectively.
Bactericidal effect during 96h growth in nutrient broth was detected with
picloxydine concentrations ≥54.25 µg/mL for E. coli and ≥27.12 µg/mL for
P. luteola.
Incubation of P. aeruginosa
or E. coli (108 CFU/mL) directly in Vitabact (434 µg/mL
picloxydine) for 15min caused complete loss of CFU as observed by subsequent
cultivation on agar plates at
With regard to the results of pain
levels, the value of pain after the IVI procedure was 7 points (±2). After
Tobrex or Vitabact treatment, we observed reduction of pain to 0 points in the
both groups within the first 24h of application of eye drops.
DISCUSSION
In our study, at least two of the three patients who had
to undergo the IVI procedure showed conjunctiva bacterial contamination: in
groups N3 (n=20) and N4 (n=20) the baseline swabs of 14 and 13
patients were positive. Consistent with other studies[5],
the majority of bacteria were CoNS (71%-77%) followed by S. aureus (15%-21%)
and single Gram-negatives. Among CoNS, the most frequently isolated was S.
epidermidis (70%-100%). S. epidermidis is believed to prevent the
colonization of conjunctiva by more serious pathogens[16].
CoNS (93%, 87% of these S. epidermidis) and S. aureus (7%)
constituted the ocular flora in the control group (n=20).
Antibiotic resistance rate of ocular flora and especially
CoNS in potent ophthalmic patients (groups N3 and N4, preoperatively) requires
increased attention when prescribing pre- and post-injection prophylactic
antimicrobials. Along with S. aureus and Gram-negative isolates
susceptible to most antibiotics, 40%-50% of CoNS in our study were MDR. In view
of the continuing practice of antibiotic eye drops prophylactic peri-injection
treatment in the Russian Federation, we should mention that CoNS resistant to
gentamycin/tobramycin were found in 20% and to moxifloxacin in 10% of potent
ophthalmic patients.
The patients who received 20 or more IVIs and concomitant
prophylactic courses of antibiotic therapy, showed a significant increase in
the resistance of the conjunctival flora to a wide range of antibiotics.
Percentage of MDR strains reached 75% of all isolates and doubled among CoNS
(90%). These patients received courses of antibiotic eye drops Tobrex based on
aminoglycoside tobramycin (in some courses replaced by Maxitrol containing
aminoglycoside neomycin, polymyxin B and dexamethasone). As the result, we
found 4.5 times increase of tobramycin resistant strains (90%) as compared with
those isolated preoperatively in groups 3 and 4 (20%). Thus, we strongly
suggest testing susceptibilityin patients who are planning to undergo repeated
IVI. The results of the test would help the surgeon to avoid prescribing
unnecessary and even threatening antibacterial drug and to choose the most
appropriate one.
Nowadays asepsis and antisepsis are beneficial rather
than use of topical antibiotics as a prevention method of post-injection
complications[4]. Aseptic and antiseptic
techniques include performing injections in the operating rooms, application of
povidone-iodine and peri-injection prophylactic treatment with antiseptic
drops. Ultraclean air and good ventilation are required in operating rooms[2]. In order to reduce the risk of infection, the spread
of pathogens from the oral cavity of patients and medical personnel should be
minimized[17] by using sterile masks by surgeons
and nurses and sterile adhesive eye drapes that isolate patients’
nasopharyngeal area and periocular region[18]. It
is important to prevent the contact of eyelashes and eyelid margins from the
injection site and the needle, through which the medication is injected into
the vitreous cavity. This can be achieved by using an eyelid speculum which
remove the eyelashes, potential source of infection of the needle tip[17]. The preparation of the ocular surface should include
irrigation with a solution of povidone-iodine for at least 30s[19]. Precisely, irrigation of the conjunctiva is needed,
not a drop application of the solution, that corresponds to Safar and Dellimore[20] findings. A single application of povidone-iodine
demonstrates a bactericidal effect, equivalent to the 3-day course of local
antibiotics[21]. Several studies have shown that
resistance to povidone-iodine does not develop[22-23] unlike the reported reduced levels of susceptibility
to chlorhexidine[24], so we can safely continue
using povidone-iodine solution in the operating rooms.
As to pre- and post-injection prophylaxis, in patients,
who used the Vitabact antibacterial eye drops 3d before the first IVI and
within 5d after it, 80% of swabs taken the day after the end of the treatment
were negative. Thus, the effectiveness of a single pre- and post-injection
course of Vitabact was close to that of Tobrex (90% of negative swabs). Among
positive conjunctival swabs taken the day after the end of post-injection
treatment with Tobrex or Vitabact, 2 and 4 isolates were found, respectively.
However, these isolates differed in their resistance to certain antibiotics from
those found at baseline in the same patients. This means that the isolates
found at baseline were eliminated with the povidone-iodine irrigation before
the injection and/or eye drops treatment. Most likely, after the end of the eye
drops post-injection treatment a rapid, within one day, recolonization of the
conjunctiva occurred.
In the in vitro study with microdilution test, picloxydine
inhibited the growth of 39 CoNS, 5 S. aureus, E. coli and P.
luteola isolates regardless of their antibiotic susceptibility. The
picloxydine MIC for staphylococci was ≥13.56 µg/mL. Another test with
incubation of bacteria 15min in Vitabact eye drops, commercially available form
of picloxydine with concentration 434 µg/mL, resulted in total loss of CFU of
10 conjunctival Gram-positive isolates, both antibiotic susceptible or MDR, and
Gram-negative E. coli and P. aeruginosa.
There is a cohort of patients complaining of pain after
the IVI. This pain is usually associated with perioperative antisepsis with
povidone-iodine, rather than the procedure itself[25].
That’s why the absence of discomfort, which we observed in patients who used
Vitabact or Tobrex eye drops after the IVI, is an important positive feature.
Moreover, patients told that the pain after the IVI decreased with application
of these drops even within the first 24h.
In conclusion, the confirmed efficacy of eye antiseptic
picloxydine against conjunctival bacterial isolates and the presence of its
commercial form, 0.05% eye drops, convenient for use by patients before and
after injection, make this eye antiseptic promising for prophylaxis of
IVI-associated infectious complications.
ACKNOWLEDGEMENTS
Conflicts of Interest: Budzinskaya MV, None; Khalatyan AS, None; Strakhovskaya MG, None;
Zhukhovitsky VG, None.
REFERENCES