Susceptibility of conjunctival bacterial pathogens to ...

Publis hed Quar ter ly Mangalor e, S outh I ndia IS S N 0972-5997 Volume 2; I s s ue 3; July- S eptember 2003

Or igin al Ar t icle

S u s cept ibilit y of con j u n ct ival bact er ial pat h ogen s t o f lu or oqu in olon es : A com par at ive s t u dy of cipr of lox acin , n or f lox acin an d of lox acin

I du, F . K ., Odj im ogho, S . E . Depar tment of Optometr y, Univer s ity of B enin, P. M. B . 1154, B enin City. E- mail: faus tikem@

Cit at ion : I du, F. K ., Odj imogho, S . E. S us ceptibility of conj unctival bacter ial pathogens to fluor oquinolones . A compar ative s tudy of cipr oflox acin, nor flox acin and oflox acin. Online J Health Allied S cs . 2003; 3: 1

U R L : http: //oj has .or g/is s ue7/2003- 3- 1.htm

Open Acces s Ar ch ive: http: //cogpr ints .ecs .s oton.ac.uk/view/s ubj ects /OJHAS .html

Abs t r act

I n or der to deter mine the mos t common bacter ia implicated in conj unctivitis , and the effectivenes s of the antibiotic Fluor oquinolone for its tr eatment, a total of 50 s ubj ects (100 ) eyes , between the ages of 1- 30 year s with mean age of 16.94 ? 8.06 year s with infected eyes , wer e ex amined at the Lagos S tate Univer s ity T eaching Hos pital, Niger ia (LAS UT H). Conj unctival s wabs wer e collected and cultur ed in the labor ator y to is olate the pathogens r es pons ible for the infection. S ens itivity and antibiotic s us ceptibility tes ts wer e car r ied out with dis cs impr egnated with 0.3% concentr ation of ophthalmic topical s olutions of chibr ox in (Nor flox acin), cilox an (Cipr oflox acin), and ocuflox (Oflox acin), to as cer tain the mos t s ens itive of the thr ee dr ugs . T he r es ults s howed that the implicated bacter ia in or der of decr eas ing fr equency wer e S taphylococcus aur eus (34% ), followed by S tr eptococcus pneumoniae (22% ), Ps eudomonas aer uginos a (14% ), Klebs iella pneumoniae (12% ), Hemophilus influenzae (9% ), Es cher ichia coli (9% ). All the is olated or ganis ms wer e highly s ens itive to the thr ee dr ugs . However , a one way analys is of var iance (ANOVA) s howed a s ignificant differ ence in the s ens itivity of the thr ee dr ugs (p< 0.05). ANOVA Pos t Hoc located Cipr oflox acin as the s our ce of the s ignificance. I n conclus ion ther efor e, Cipr oflox acin is the mos t s ens itive of the thr ee dr ugs and, hence

s hould be the fir s t choice of the fluor oquinolones for the tr eatment of bacter ial conj unctivitis .

I n t r odu ct ion

B acter ia ar e the mos t common micr oor ganis ms that caus e conj unctivitis (inflammation of the conj unctiva). T his is s o becaus e the bacter ia pathogens inhabit the ocular s ur face (i.e. mucous membr ane of the conj unctiva) though the lys os omes and antibodies in tear film along with the blinking mechanis m keep their population in check. T he mos t common bacter ia micr oor ganis ms implicated in bacter ial conj unctivitis include S taphylococcus aur eus , Neis s er r ia gonor r hoeae, S tr eptococcus pneumoniae, Haemophilus influenzae, Mor ax ella lacunata, Cor ynebacter ium diphther iae.(1)

T her e ar e two types of bacter ial conj unctivitis ; acute and chr onic. T he acute s tage is clas s ically r ecognized by vas cular engor gement and mucopur ulent dis char ge with as s ociated s ymptoms of for eign body s ens ation, ir r itation, and s ticking together of the lids . T he chr onic s tage is mor e innocuous in ons et, it r uns a pr otr acted cour s e and is often as s ociated with the involvement of the eyelids , lacr imal s ys tem or lowgr ade inflammator y r eaction. Although maj or ity of

1

bacter ial conj unctivitis ar e s elf limiting, without need for medical inter vention, s tudies have demons tr ated that antibiotic ther apy has tens the er adication of bacter ia, pr events the dis s emination of the infection to other s tr uctur es , decr eas es the r is k of s ys temic dis eas e, r educing per s on to per s on s pr ead and s hor tens the s ymptomatic per iod allowing the patient to r etur n mor e quickly to his or her nor mal activities .(1- 3)

Mos t times pr imar y eye car e pr ovider s s tar t the tr eatment of ex ter nal ocular infection befor e the caus ative micr o- or ganis ms have been identified, or s ubmitted to antibiotic s us ceptibility tes ts . Cons equently, br oad- s pectr um antibiotics ar e r outinely us ed in the tr eatment of bacter ial conj unctivitis . Of the many antibiotics in us e is the gr oup of fluor oquinolones - par ticular ly Cipr oflox acin (cilox an), Oflox acin (ocuflox ) and Nor flox acin (chibr ox in). Flour oquinolones ar e s ynthetic quinolone der ivatives with fluor ine atom in the 6th pos ition. T he addition of the fluor ine atom impr oves its potency, enhances the antimicr obial activity and alter s the phar macokinetic pr oper ties with tr emendous ther apeutic advantage over nalidix ic acid. T heir mechanis m of action is unique among available antibiotics s ugges ting that cr os s r es is tance to fluor oquinolones can be minimized.(4) T he br oad s pectr um of activity of the fluor oquinolones per mits their us e in a var iety of infections including thos e affecting the r es pir ator y tr act, ur inar y tr act, s kin, s oft tis s ues and eyes . T he ear lies t fluor oquinolones wer e pr edominantly agains t gr am negative agents es pecially Enter obacter iaceae. T he newer fluor oquinolones als o ar e active agains t gr am negative or ganis ms but offer a br oader s pectr um of activity, including cover age of gr am pos itive and atypical bacter ia. T hey have gained popular ity in ocular ther apy due to their efficacy in the tr eatment of bacter ial cor neal ulcer s . T hes e dr ugs ar e available in topical and or al for ms . T he cur r ent topical for mulation ar e in 0.3% concentr ations . Each has dis tinct clinical char acter is tics , differ ences in s olubility and pr ecipitate for mation.(5)

S tudies dir ectly compar ing the efficacy of the

fluor oquinolones ar e s par s e. However , s tudies

conducted by s ome r es ear cher s (5- 8), have s hown

that antibiotic of the fluor oquinolone gr oup wer e

mor e effective in the tr eatment of ocular infections

than s ome other br oad s pectr um antibiotics eg.

gentamycin,

chlor amphenicol,

tobr amycin,

er ythr omycin and tetr acycline. T he s tudy by Jauch

(8) has als o s hown that S taphylococcus aur eus is a

common pathogen in bacter ial infection. T he aim of

this s tudy ther efor e was to identify the common

bacter ial pathogens that caus e conj unctivitis and the

mos t s ens itive of the thr ee topical fluor oquinolones

under s tudy for its tr eatment.

ME T H OD OL OGY S t u dy popu l at i on T he s tudy population compr is ed of 50 s ubj ects (100 eyes ), between the age r ange of 1- 30 year s who

wer e diagnos ed to have bacter ial conj unctivitis at the Lagos S tate Univer s ity T eaching Hos pital, Niger ia (LAS UT H).

P r ocedu r e

Conj unctival s wabs wer e collected fr om both eyes of each s ubj ect us ing s ter ile cotton tipped applicator wiped twice acr os s the lower conj unctival cul- de s ac fr om the tempor al to the nas al r egion. T he s wabs wer e labelled and taken to the labor ator y within two hour s of collection. I n the labor ator y, it was placed in a medium and inoculated.

P r epar at i on of m edi u m

B oth blood and chocolate agar wer e us ed. T he powder ed medium was mix ed with water and s teamed to dis s olve the agar . T he whole mix tur e was then s ter ilis ed in an autoclave at 121? C and s ubs equently allowed to cool to about 45? C, a temper atur e at which the agar r emained molten. Plates wer e then pr epar ed by pour ing s ome 15 ? 20 ml of the molten agar medium into s ter ile Petr i dis hes which wer e left undis tur bed until the agar s et. B lood agar was made by mix ing molten agar at about 45? C- 50? C with 5 - 10% volume of blood befor e pour ing into the plates . Chocolate agar was made by heating blood agar to 70? C - 80? C until it became chocolate br own in colour . I n ocu l at i on of m ediu m T he s olid medium was inoculated us ing the s tr eaking method which involved the pr ogr es s ive thinning out of the inoculum in s uch a way that the s epar ated cells wer e left in at leas t s ome ar eas of the plate incubated at 37? C for 24 hour s .

An t i bi ot i c s u s cept ibi l it y t es t of or gan is m s is olat ed u s ing t h e dis c dif f us ion m et h od

Cultur es of the identified or ganis ms on the bas is of all the var ious tes ts car r ied out wer e s tr eaked evenly on the Petr i dis hes with s ter ile cotton wool s wabs . (T able 1)

Dis cs impr egnated with two dr ops (5 mcg) each of ophthalmic topical s olutions of Cipr oflox acin, Nor flox acin and Oflox acin wer e placed on them with the aid of a flamed for ceps , incubation was done for 24 hour s at 34? C.

Z one of inhibition of gr owth r anging fr om 5 mm and above ar ound the s pecific antibiotic dis c indicated s ens itivity to that par ticular antibiotic, while a total abs ence of s uch a zone of inhibition indicated complete r es is tance.

S t at i s t i cal An alys is

A one way analys is of var iance (ANOVA) was us ed to analys e the s ens itivity of the thr ee dr ugs . ANOVA pos t Hoc us ing B onfer r oni was us ed to deter mine the s our ce of s ignificance.

2

RESULT S

T able 1 s hows the char acter ization and identification of the bacter ial is olates , while T able 2 s hows the per centage occur r ence of the is olated bacter ia. S . aur eus had the highes t occur r ence of 34% , while H. influenza and E.coli had the leas t occur r ence of 9% each. T able 3 and Figs . 1- 3 s how the zones of inhibition of each dr ug agains t the bacter ial is olates . Cipr oflox acin had the highes t zones of inhibition on all the bacter ial is olates followed by Oflox acin and then Nor flox acin. I n or der to us e a par ametr ic tes t, the data obtained wer e tr ans for med into their natur al logar ithms . T he one factor ANOVA s howed that the differ ence in zones of inhibition was

s tatis tically s ignificant (F 2,15= 15.05, p < 0.05). Pos t Hoc us ing Bonfer r oni located Cipr oflox acin as the s our ce of the s ignificant declar ed in one factor ANOVA.

T abl e 1 : Ch ar act er i s at i on an d iden t i f i cat i on of bact er ial is olat es + Pos itive T es t; - Negative T es t

Mor phology

Rods in s hor t chains Cocci in pair s Rods in long chains and clus ter s S hor t r ods in pair s Cocci in clus ter s Cocci in chains

Gr am s t ai n

+ +

Cat al as e

+ + + + -

Coagu l as e

+ -

Ox idas e

+ + -

P r obable ident it y of

is olat es E. coli

N. gonor r hoeae P. aur euginos a K. pneumoniae

S . aur eus S . pneumoniae

T abl e 2 . P er cen t age occu r r en ce of i s ol at ed m i cr oor gan is m

Micr o Or ganis m I s olated 1. S taphylococcus aur eus 2. S tr eptococcus pneumoniae 3. Ps eudomonas aer uginos a 4. Klebs iella pneumoniae 5. Haemophilus influenzae 6. Es cher ichia coli

Fr equency 34 22 14 12 9 9

% Occur r ence 34% 22% 14% 12% 9% 9%

T abl e 3 . Z on e of in h i bit i on of each dr u g agai n s t i s ol at ed m i cr o or gan is m

Micr o Or ganis m

Cipr oflox acin

Nor flox acin

1.

S taphylococcus aur eus

2.

S tr eptococcus pneumoniae

3.

Ps eudomonas aer uginos a

4.

Klebs iella pneumoniae

5.

Hemophilus infuenzae

6.

Es cher ichia coli

1 7 mm 1 6 mm 1 7 mm 1 6 mm 1 8 mm 1 4 mm

1 1 mm 1 2 mm 1 0 mm 1 0 mm 1 2 mm 1 0 mm

Oflox acin

1 4 mm 1 4 mm 1 3 mm 1 3 mm 1 5 mm 9mm

3

Fig 1: His togr am of zones of inhibition of S . aur eus and S . pneumoniae

Fig 2: His togr am of zones of inhibition of P. aer uginos a and K. pneumoniae

Fig 3: His togr am of zones of inhibition of H. influenzae and E. coli

4

D i s cu s s i on

S taphylococcus aur eus , S tr eptococcus pneumoniae, Ps eudomonas aer uginos a, Klebs iella pneumoniae, Haemophilus influenzae and Es cher ichia coli wer e the bacter ia pathogens is olated in or der of decr eas ing fr equency fr om the s wabs taken to the labor ator y. T he caus e of bacter ial conj unctivitis is the alter ation in the nor mal flor a, which can occur by ex ter nal contamination by s pr ead fr om adj acent s ites or via a blood ? bor ne pathway. T he pr imar y defens e agains t infection is the epithelial layer cover ing the conj unctiva. Dis r uption of this bar r ier can lead to infection.

S taphylococcus aur eus having the highes t pr evalence amongs t the or ganis ms implicated is cons is tent with the claim that it is the mos t fr equent caus e of bacter ial conj unctivitis wor ldwide.(9- 11) T he gr am- pos itive bacter ia is olated wer e S taphylococcus aur eus and S tr eptococcus pneumoniae while the gr am- negative ones wer e Ps eudomonas aer uginos a, Klebs iella pneumoniae, Haemophilus influenzae and Es cher ichia coli.

I n childr en, Haemophilus , S tr eptococcus and S . aur eus ar e the common pathogens is olated. S tr eptococcal infections ar e s elf limiting and may occur in epidemics . T hey ar e mor e fr equent in temper ate climates and winter months and ar e as s ociated with s ub- conj unctival haemor r hages .(9) Conj unctivitis due to Haemophilus influenzae ar e often epidemic but may be endemic in war mer climates . T hey ar e als o as s ociated with s ubconj unctival haemor r hages .(1- 3)

Cipr oflox acin had the highes t s ens itivity over the other two antibiotics as all the or ganis ms is olated s howed highes t s us ceptibility to it followed by Oflox acin and then Nor flox acin. T his is cons is tent with the s tudy car r ied out by B r ower et al (5), which s howed the high efficacy of Cipr oflox acin in the tr eatment of bacter ial ker atitis . Cipr oflox acin ex hibited it's highes t s ens itivity on Haemophilus influenzae with a zone of inhibition of 18 mm. while it's leas t s ens itivity was s een on Es cher ichia coli with 14 mm zone of inhibition. T he highes t s us ceptibility to Nor flox acin was ex hibited by S . pneumoniae and H. influenzae with 12 mm zone of inhibition each. T he highes t s us ceptibility to Oflox acin was ex hibited by H. influenzae with a zone of inhibition of 15 mm.

Con cl u s i on

T he s tudy has s hown that S taphylococcus aur eus is the mos t caus ative micr o- or ganis m implicated in bacter ia conj unctivitis . All s ix is olated bacter ia wer e s us ceptible to flour oquinolone with Cipr oflox acin as the mos t s ens itive dr ug, followed by Oflox acin, and the leas t was Nor flox acin. T hus Cipr oflox acin is the mos t effective of the thr ee dr ugs and it is ther efor e r ecommended as the bes t choice of topical fluor oquinolone antibiotic for the tr eatment of bacter ial conj unctivitis .

R ef er en ces

1. Vaughan D, As bur y T , Riodan- Eva P. Gener al Ophthalmology, Lange Medical publication, 15th ed. 1996; PP 96- 67.

2. Kans ki JJ. Clinical Ophthalmology. 3rd ed. B utter wor th- Heinemann- I nt'l ed. Wobur n, MA; 1998.p. 514.

3. Yetman R, Coody D. Conj unctivitis : A pr actice guideline. J Pediatr ic Health Car e. 1997; 11(5):238-44

4. Wolfs on, JS , Hooper DC. T he fluor oquinolones : s tr uctur e, mechanis m of action and r es is tance and s pectr a of activity in vitr o. Antimicr obe Agent chemother . 1985; Pp 28,58.

5. B r ower , K., Kowals ki, R Gor don M. Flour oquinolones in the tr eatment of bacter ia ker atitis Am J Ophthalmol 1996; 121: 712-5.

6. Lu, KL Pr aj na, NV, Macdonell, PJ. Compar is m of Oflox acin and Cipr oflox acin in the ther apy of bacter ia ker atitis . I nves t Ophthalmol Vis S ci 1998; 39: 5140.

7. O'br ian, T P, Maguir e, MG, Fink, NE, Alfons o E, Mcdonnell P. For the bacter ial ker atitis s tudy gr oup. Efficacy of oflox acin vs Cefazolin and T obr amycin in the ther apy of bacter ial ker atitis . Ar c ophthalmol. 1995; 113: 1257-65.

8. Jauch, A. et al Meta analys is of s ix clinical phas e I I I s tudies compar ing 0.3% lomeflox acin twice daily with five s tandar d antibiotics in patients with acute bacter ial conj unctivitis . Gr aefs Ar ch Clin Ex p Ophthalmol. 1999; I n pr es s .

9. B aum, JL. B acter ial conj unctivitis : Diagnos is and T r eatment. APUA News letter . 1997; 15(4): 1, 4-5, 8.

10. Haes aer t, PS . Clinical manual of ocular micr obiology and cytology, Mos by year book. 1993; pp 30- 32, 68, 102, 114- 115.

11. Pr es cott LM, Har ley JP, Klein DA. Micr obiology. 4th ed. McGr aw- Hills Co, U.S .A; 1999. p. 780.

5

 ................
................

In order to avoid copyright disputes, this page is only a partial summary.

Google Online Preview   Download