Dr. Shetal M. Raj, DO, MSDr. D. U. Gajjar, Ph.DDr. Abhay R. Vasavada, MS, FRCS

Residual Conjunctival Flora After 2 Regimes of Topical Vigamox:

Prospective Randomized Triple-Masked Trial

The authors do not hold any financial interest

Iladevi Cataract and IOL Research Centre, Ahmedabad, India

AIMTo compare two dosing regimes of topically administered Vigamox (Moxifloxacin 0.5%, Alcon Lab., USA) with respect to:

1. Reduction in number of conjunctival bacterial flora 2. Bacterial species of conjunctival bacterial flora

Study designProspectiveRandomizedMasked trial

80 patients undergoing phacoemulsification from December 2006 to December 2007.

Sample collection and processing: • Swabs were collected at two time points before and after instillation of the

antibiotic regime.

Material and Method

Swabs were obtained without anesthesia by inserting the moist swab in the lower conjunctival fornix at the nasal margin and rotating it along the fornix to the temporal margin. The same swab was then rotated along the margins of upper and lower eyelid.

The swab was inoculated into a bijou bottle containing 2 ml tryptone soya broth with 0.5% Sodium thiosulphate broth and transported to the microbiologylaboratory within 30 minutes

The patients were randomly assigned to either group:

NO

versusSame Day Regime (n=40 eyes)

Previous day regime

(n=40 eyes)

commenced two hours prior instilled at

every 15 minutes only in the first hour

Previous day 4 times a day

one drop two hours prior

(a total of 5 drops )

(a total of 5 drops )

+

I.

II. III.

Samples were vortexed for 30 second. Subsequently, three aliquots Samples were vortexed for 30 second. Subsequently, three aliquots 100 ul were collected from the sample and each aliquot was spread 100 ul were collected from the sample and each aliquot was spread on:on:

A

Chocolate agarChocolate agarincubated for 48 hrsincubated for 48 hrs

in 10% COin 10% CO22

Blood agar Blood agar incubated for 48 hrs incubated for 48 hrs

in 10% CO2in 10% CO2

Nutrient agar Nutrient agar incubated for 48 hrs, incubated for 48 hrs,

aerobicallyaerobically

The bacterial growth was evaluated in:The bacterial growth was evaluated in:

1. 1. Quantitative manner Quantitative manner as colony forming units (CFU) using an as colony forming units (CFU) using an illuminated grid colony counterilluminated grid colony counter

Total CFU/ eye = (CFU on plate per amount of solution plated) Total CFU/ eye = (CFU on plate per amount of solution plated) x (volume of original solution)x (volume of original solution)

2. 2. Qualitative manner Qualitative manner for identification of speciesfor identification of species

PIBWIN SOFTWARE

Gram stainingMotility MR VP Citrate

Coagulase test

Amylase

Carbohydrate utilization

Bacterial species were identified using conventional bio-chemical and biophysical reactions and using the PIBWin ---Software for probilistic identification

Qualitative manner Qualitative manner

Statistical analysis:

• Wilcoxon Signed Ranked Test to compare within each regimen (pre verses post)

• Mann Whitney Test to compare between the regimen (post verses post)

• Test of Proportions was done for comparing presence or absence of specific bacteria.

• Multiple linear regressions were used to compare the two regimen between pre-irrigation and post-irrigation CFU, using the logarithms of the counts.

Comparison of the reduction in CFU after instillation of two prophylactic regimens of vigamox.

CFU(Colony Forming

Units)

•Within each regimen, the % reduction in median CFU from pre to post-instillation in: - previous day regime was 94% (p<0.001) - same day regime was 95% (p<0.001) •The % reduction in colony counts between the regimen was similar. (P=0.09).

RESULTS - Quantitative

Previous day regime Same

day regime

LOGPRE

3.83.63.43.23.02.82.62.4

DIF

LO

GIN

0.0

-.5

-1.0

-1.5

-2.0

-2.5

REGIME

2

1

Total Population

Multiple linear regression analysis of the change in log CFU between pre and post antibiotic instillation against pre antibiotic CFU, with separate regression lines fitted to each group.

The steep gradient of line in the same day regime (regimen 2) implies that the same day regime was more effective relative to previous day regime (regimen 1).

S. epidermidis

Corynebacterium sp.

Micrococcus sp.S. epidermidis

Most commonly occurring bacteria in both the groups

Pseudomonas sp.+ other gram negatives

Bacillus sp. AnaerobesPropionebacterium

Peptostreptococcus

RESULTS - Qualitative

% of eyes

Previous day

regime

Same day

regime

P Value

Staphylococcus sp. 79.1 67.10.81

Corynebacterium sp. 42.6 230.17

Micrococcus sp. 4 160.59

Bacillus sp. 0 0

Gram negative rods 8 81.00

Anaerobes 54.6 45.30.42

Comparison of bacterial isolates on the plates post-instillation of antibiotic in both the groups

There was no statistically significant difference between the regimens after instillationwith respect to the number of isolates of each of different bacteria.

Literature Review

• Lichtenstein SJ, Wagner RS, Jamison T, Bell B, Stroman DW. Speed of bacterial kill with a fluoroquinolone compared with nonfluoroquinolones: clinical implications and a review of kinetics of kill studies. Adv Ther. 2007;24(5):1098-111

-Moxifloxacin kills bacteria more rapidly than nonfluoroquinolone topical ocular antibiotics

• Bucci FA Jr, Amico LM, Evans RE. Antimicrobial efficacy of prophylactic gatifloxacin 0.3% and moxifloxacin 0.5% in patients undergoing phacoemulsification surgery. Eye Contact Lens. 2008;34:39-42.

-No differences were observed between the antibiotics in mean pre-operative CFUs in conjunctival cultures or eyelid cultures.

• Fahmy JA, Møller S, Bentzon MW. Bacterial flora of the normal conjunctiva. II. Methods of obtaining cultures. Acta Ophthalmol (Copenh). 1975;53:237-53.

1. A prospective, randomized, triple masked trial 2. An adequate sample size 3. Investigated both qualitatively and quantitatively the conjunctival and eyelid

cultures to compare the effect of two regimens 4. The methodology used for bacterial identification was highly precise and sensitive. 5. The bacterial species identity was confirmed using the 16srRNA sequence based

phylogenetic analysis.

STRENGTH

Comparison of these regimens with other fluroquinolones.

LIMITATION

CONCLUSIONBoth regimens of moxifloxacin, i.e previous day and same day are effective in reducing the conjunctival flora when used for preoperative prophylaxis of intraocular anterior segment surgery.

There was no added advantage of commencing moxifloxacin on the previous day in comparison to the same day regimen with respect to their effect on the surface kill of normal flora.