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Al-Shifa
Journal of
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Aims and Scope
Ocular Infections and Seasonal Variations Sensitivity of Tests in Dry Eyes Intravitreal Kenacort in Macular Edema ERG in Diagnosis of Retinal Problems Spectrum of Contact Lens Users |
Antimicrobial Sensitivity Pattern of Pre-Operative cases at Al- Shifa Trust Eye Hosp Rawalpindi Tania Rab M.Sc (Biological Sciences), M.Phil (Microbiology), Tayyab Afghani MBBS, MS (ophthalmology) Mussarrat Aziz B.Sc Nursing Purpose: To review the distribution and shifting trends of bacterial culture specimens in preoperative cases in an eye hospital and to assess the sensitivity pattern of isolated organisms to the treatment regimen utilized Design of Study: Retrospective analysis of record of 2,050 hospital indoor pre-operative patients. Participants: 2,050 hospital patients admitted during two year period for intra-ocular surgery without any symptom of ocular infection. Methodology: Conjunctival swabs for microbiological examination were taken from patient’s eye to be operated. The samples were examined by gram staining and cultured on Blood Agar, Chocolate Agar, Brain Heart infusion broth, and thioglycolate broth. Cultures were maintained for 7 days. Antibiotic susceptibility of these isolates was determined for various ocular antibiotics using the Disk Diffusion Susceptibility Test. Results:
Ocular surface infection was documented in 23% of otherwise
non-symptomatic pre-operative admitted patients. 75% were attributable to gram-positive, while 25% were due to
gram-negative. No fungal growth was observed. Amongst the gram positive,
Staph aureus had the highest prevalence of 41% followed by Strept
pneumoniae of 11.5%. Gram-negative bacteria predominantly isolated were
Pseudomonas aeruginosa, which represented 6%. Antimicrobial
susceptibility results revealed variable degrees of susceptibility in
the isolates from our preoperative cases.
The over all gram-positive strains demonstrated highest
sensitivity to Keflax (82%) and then to Ciprofloxacin (56%). The
gram-negative bacteria presented with highest sensitivity to Ofloxacin
(85%) followed by Ciprofloxacin (74%). |
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eye surface is rich in proteins, carbohydrates, lipids, and electrolytes
exposed to the air, with no physical barrier
between germs. Consequently they support a rich commensal flora of
micro-organisms. Species commonly present on the surface of the eye
include Diptheroids, Staphylococcus, and Streptococcus. The presence of
a commensal flora, together with the physical action of the lids and the
chemical effect of the tears, normally prevents colonization by
pathogenic bacteria. However, infection of the external surface of the
eye are common and result from either the acquisition of a particularly
virulent microorganism or uncontrolled growth of an existing bacterium
due to lowered host resistance or disruption of physical barriers1-3. Originally
received: July 1, 2004 Generally, postoperative endophthalmitis is caused by the perioperative introduction of microbial organisms into the eye either from the patient’s normal conjunctival and skin flora, from the air, from the surface or from contaminated equipment4-6. Fortunately, the incidence of endophthalmitis after intraocular surgery is very low7 and has not changed much over the last decade; the rate of infection after cataract surgery is approximately 0.08% but in more complicated surgeries and penetrating ocular traumas the rates are higher8. The
majority of endophthalmitis cases (approximately 75% to 95%) involve
organisms from the conjunctiva in the periocular area, and include
coagulase negative Staphylococci, Staphylococcus epidermidis,
Staphylococcus aureus and anaerobic organisms such as propionibacterium
acnes9.
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Purpose
The present study was undertaken to review the distribution and shifting trends of bacterial culture specimens in preoperative cases in an eye hospital and to assess the sensitivity pattern of isolated organisms to the treatment regimen utilized. Patients
and methods
The
data was collected between January 2001 to December 2002. Preoperative
conjunctival smears of 2,050 hospital indoor patients without signs of
ocular infection were therefore examined by culture. Departments of
ophthalmic research center and clinical microbiology lab took part in the
study.
We
took conjunctival swabs for microbiological examination from patient’s
eye to be operated. The samples were examined by gram staining and
cultured on Blood Agar, Chocolate Agar, Brain Heart infusion broth, and
thioglycolate broth. For aerobic bacteria, only heavy growth from one
solid medium or isolation of the same organism from more than one type of
medium was considered significant and not a contaminant. Anaerobic growth
on any medium incubated anaerobically was considered significant. Cultures
were maintained for 7 days. If no organism was isolated the case was
considered culture negative even if the organisms were thought to be
present on the smear. Antibiotic susceptibility of these isolates was
determined for various ocular antibiotics using the Disk Diffusion
Susceptibility Test.
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Results Out of 2,050 pre-operative conjunctival swabs
we have found 470(22.92%) positive cultures.
Among 470 infected cases, 351 (74.68%) were attributable to
gram-positive, 119 (25.31%) to gram-negative. No fungal growth was
observed Staph aureus
had the highest prevalence of 192 (40.85%) followed by Strept pneumoniae
54 (11.48%). Similarly Staph spp other than staph aureus and staph
epidermidis was 57(12.12%), Staph epidermidis was 20 (4.25%). (Table1).
Gram-negative bacteria predominantly isolated were Pseudomonas
aeruginosa, which represented 30 (6.38%) and other Pseudomonas spp 12
(2.55%). Antimicrobial susceptibility results revealed variable degrees
of susceptibility in the isolates from our preoperative case. The over all gram-positive strains
demonstrated highest sensitivity to Keflax 121 (81.75%) and then to
Ciprofloxacin 127 (56.19%) and Cephadine 136(55.96%) which showed equal
levels of susceptibilities, chloramphenicol was sensitive to 101(48.3%).
The gram-negative bacteria presented with highest sensitivity to
Ofloxacin 22(84.61%) then to Ciprofloxacin 48 (73.84%). Norfloxacin
23(63.88%) and Gentamicine 33(57.87%) showed almost equal level of
sensitivity. Among
gram-positive bacteria, Staph aureus 97 out of 119 were sensitive to
Keflax, 32 out of 50 (64%) to Cephazolin, 45 of 77 (58.4%) to Ofloxacine
and 90 of 166 (54.2%) to Ciprofloxacin. Strept pneumoniae exhibit
highest sensitivity to both Chloramphenicol 22 out of 28 (78.5%) and
Keflax 14 out of 18 (77.7%) and than to Ofloxacine 12 out of 17 (70.5%).
Staph Epidermidis showed susceptibility to Keflax 4 out of 4 (100%) than
to Cephadine 14 out of 18 (77.7%) than to Cephazolin 8 out of 12
(66.6%). Corynebacterium displayed sensitivity to both Gentamicine and
Ciprofloxacin 5 out of 10 (55.5%). Strept pyogenes showed Keflax 6 out
of 7 (85.7%), Cephadine 5 out of 6 (80) and Chloramphenicol 8 out of 10
(80%) Gram-negative bacteria have shown a very
diverse pattern of sensitivities. Pseudomonas aeruginosa was 100%
sensitive to Ofloxacine & Fusidic acid and 72%. Haemophilus
Influenza showed 100% sensitivity to Keflax and Amoxicilline and 66% to
Norfloxacin and Cephadine. |
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Table 1: The bacteria isolated from preoperative conjunctival smears.
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Table
2 : Sensitivity Pattern of Gram-positive Bacteria –No(%)
KEY:
Kef =Keflax, Amx =Amoxicillin, Tet =Tetracycline, Gen =Gentamicin, Cip =Ciprofloxacin,
Ofx =Ofloxacin, Pg =Pencillin G, Tob
=Tobramycin, Chl =Chloramphenicol, Nor =Norfloxacin, Cep =Cephadine,
Cefz = Cefazoline, Fusd =Fusidic acid, Erth =Erythromycin, Aug =Augmentin,
Amp =Ampicillin
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Table 3 : Sensitivity Pattern of Gram-Negative Bacteria-No (%)
KEY:
Kef =Keflax, Amx =Amoxicillin, Tet =Tetracycline, Gen =Gentamicin, Cip =Ciprofloxacin,
Ofx =Ofloxacin, Pg =Pencillin G, Tob
=Tobramycin, Chl =Chloramphenicol, Nor =Norfloxacin, Cep =Cephadine,
Cefz = Cefazoline, Fusd =Fusidic acid, Erth =Erythromycin, Aug =Augmentin,
Amp =Ampicillin |
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Discussion In this study out of total 2,050 preoperative
patients without signs of ocular infection, 470 (23%) cases were found
positive for pathogens. 75% were gram positive followed by 25% gram
negative. This is comparable with another study done in China where the
rate of positive culture was 28.6%11. The culture positive rate
from samples taken on normal eyes in several studies have been reported
and vary widely from 51 to 75%9,12 .This seems much higher than
that found in our study. This low culture positive rate may be due to
indiscriminate use of antibiotics commonly available over the counter. Persisting microbial colonization of the
conjunctiva may be an important factor for the development of
postoperative endophthalmitis13. In a prospective randomized
clinical trial10 that evaluated the management of acute
postoperative endophthalmitis, the most common organisms isolated were
coagulase-negative Staphylococci 70% Staph aureus 9.9% and Streptococci sp
9%. Infections caused by gram-negative organisms were seen in 6% of cases.
O’Brien12 also reported that gram-positive organisms account
for 90% to 95% of ocular infections. Streptococcus is a particularly
problematic ocular pathogen that can cause severe keratitis and
endophthalmitis12. Antibiotic susceptibility of these isolates
was determined for various ocular antibiotics. The over all gram-positive
organisms demonstrate the highest degree of sensitivity to Quinolone and
Cephalosporins. Quinolones have shown excellent coverage of gram-positive
organisms. An almost similar pattern has been observed in an Indian study6
where among gram-negative bacteria diverse pattern of sensitivities were
seen. Another study evaluated six different prophylactic regimens for
their effectiveness in eradicating bacteria on the conjunctiva before
surgery. Gentamicine sulphate ophthalmic solution was the only antibiotic
able to eliminate bacteria14. Conclusion Postoperative endophthalmitis remains a major
concern after intra-ocular surgery, despite the availability of potent
antibiotics with a large spectrum of activity. Several preoperative risk
factors can predispose to an infection. Their early recognition may
prevent a disastrous outcome. However, in some cases the infection seems
impossible to foresee. Therefore, a careful patient selection and special
attention to asepsis are mandatory. Further controlled prospective
clinical trials are needed to evaluate the necessity of pre-or
perioperative antibiotic prophylaxis, as well the choice of drug to be
used. Several studies are investigating new molecules with better
antibacterial activity and less ocular toxicity. Until these results are
available, the patient evaluation and therapeutic choice remain the
surgeon’s best judgment. References 1.
Labetoulle M, Lau tier-Frau M, Frau E. Ocular infections of the
elderly. Presse Med 2002 Oct 5; 31(32): 1521- 9. 2.
Rummelt V, Boltze HJ, Junemann A, Rollinghoff M, and Naumann GO.
Persistence and transient conjunctival pathogen colonization before
planned intraocular interventions. Klin Monatsbl Augenheilkd 1992 Oct;
201(4): 231-3. 3.
Taylor PB, Tabbara KF, Burd EM. Effect of preoperative Fusidic acid
on the normal eyelid and conjunctival bacterial flora. Br J
Ophthalmol.1988 Mar; 72(3): 206-9. 4.
Botze HJ, Rummelt V, Rollinghoff M, Naumann GO. Bacterial pathogen
and resistance spectrum of the non-irritated conjunctiva.7, 845
preoperative Smears at the ophthalmologic clinic of the Erlangen
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Sandvig KU, Dannevig L. Postoperative endophthalmitis:
Establishment and results of a national registry. Cataract
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Anand AR, Therese KL, Madhavan HN. Spectrum of etiological agents
of postoperative endophthalmitis and antibiotic susceptibility of
bacterial isolates. Indian J Ophthalmology. 2000 Jun; 48(2): 123-8. 7.
Liotet S, Preoperative Conjunctival bacterial flora and sensitivity
to antibiotics Fr Ophtalmol.1979 Aug-Sep; 2(8-9): 449-57. 8.
Okhravi N, Towler HMA, Hykin P, Matheson M, Lightman S. Assessment
of a standard treatment protocol on visual outcome following presumed
bacterial endophthalmitis. Br J Ophthalmol 1997 Sept; 81:719-725. 9.
Sunaric-Megevand G, Pournaras C. Current approach to postoperative
endophthalmitis. Br J Ophthalmol 1997; 81:1006-1015. 10.
Outbreaks of postoperative bacterial endophthalmitis caused by
intrinsically contaminated ophthalmic solutions Thailand, 1992, and Canada
1993.MMWR (CDC) 1996 June; 45(23): 491-494. 11.
Guang SX, Qun WZ, Lin L, Yuen LS, Ying JX, Hua ZW. Etiological
analysis on bacterial ocular disease in north part of China (1989-1998).
Chin Med J 2002; (6): 933-935. 12.
O’Brien TP. Antimicrobial prophylaxis in ophthalmic surgery.
Cataract & Refractive Surgery today. 2003 Sept; 102-105. 13.
Herde J, Tost M, Wilhelms D, Hohne C, Thiele T. Perioperative
conjunctival flora. Klin Monatsbl Augenheilkd.1996 Jul; 2009(1): 13-20. |
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