Al-Shifa Journal of            Ophthalmology (ASJO)               

Vol. 1, No. 1, January - June 2005
Aims and Scope

Information For Authors

President's Message

Editorial

Ophthalmoplegic Migraine

Ocular Infections and Seasonal Variations

Repair of Lost Rectus Muscle

Sensitivity of Tests in Dry Eyes

Intravitreal Kenacort in Macular Edema

ERG in Diagnosis of Retinal Problems

Spectrum of Contact Lens Users

Corneal Thickness in Diabetics

Antimicrobial Sensitivity Pattern

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%).

Conclusion: 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. Al-Shifa Journal of Ophthalmology 2005; 1: 45-52 © Al-Shifa Trust Eye Hospital, Rawalpindi, Pakistan
The 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
Accepted: October 12, 2004
Correspondence to Tania Rab, Ocular Infections Laboratory, Al-Shifa Trust Eye Hospital, Rawalpindi, Pakistan

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.


It has been observed that in terms of developing the most rational approach for reducing conjunctival colonization, the antibiotics should be administered topically in a brief preoperative regimen immediately prior to surgery, they can considerably reduce ocular surface flora compared to untreated controls. It is unclear, however, if several days of preoperative antibiotic administration is superior to management on the day of surgery. No antibiotic alone can always produce ocular surface sterility; surgeons are simply attempting to decrease conjunctival colonization10-12.

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.

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.

Table 1: The bacteria isolated from preoperative conjunctival smears.

 

S.No

Bacteria Isolated

Total number

% age out of total population

% age out of infected population

1

Staph aureus

192

9.3

40.85

2

Strept Pneumoniae

54

2.63 

11.48

3

Pseudomonas aeruginosa

30

1.46

6.38  

4

Staph Epidermidis

20 

0.97

4.25

5

E.coli 

18

0.87    

3.82

6

Haemophilus influanzae

12

0.58

2.55

7

Coryne bacterium

10

0.48

2.12 

8

Strept pyogenes
 

8

0.39

1.70

9  
 

Klebsilla

8

0.39

1.70

10  

Pasturella  

6

0.29

1.27

11

Yersinia  

6

0.29

1.27

12

Proteus  

5

0.24

1.06

13

Morxella  

4

0.19

0.85

14

Xenthomaltophillia  

2

0.097

0.42

15

Bacillus

2

0.097  

0.42

16

Other Staph spp

57  

2.78

12.12

17

Other B-hemolytic Strept spp

10

0.48

2.12  

18

Other pseudomonas spp

10

0.48

2.12  

19

Others gram negative bacteria

16

0.87

3.40  

Total

470

100

100
 

Table 2 : Sensitivity Pattern of Gram-positive Bacteria –No(%)

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Type of bacteria
Ocular antibiotics

Kef

Amx

Tet

Gen

Cip

Ofx

Pg

Tob

Chl

Nor

Cep

Cefz

Fusd

Erth

Aug

Amp

Staph aureus

 

97

(81.5)

15

(21.1)

28

(18.5)

53

(34.8)

90

(54.2)

45

(58.4)

12

(11.8)

35

(29.4)

63

(38.6)

19

(42.2)

93

(55.6)

32

(64)

48

(53)

31

(27.1)

-

-

Strept Pneumoniae

14

(77.7)

8

(50)

8

(38)

7

(21.2)

18

(64.2)

12

(70.5)

15

(65.2)

0

(0)

22

(78.5)

6

(50)

20

(66)

8

(57.1)

3

(30)

10

(41.6)

2

(33.3)

5

(38.4)

Staph Epidermidis

4

(100)

0

4

(25)

10

(55.5)

9

(64.2)

0

0

12

(52.1)

5

(35)

6

(54.5)

14

(77.7)

8

(66.6)

3

(60)

0

 

4

(33.3)

7

(77.7)

Coryne Bacterium

 

-------

0

2

(22.2)

5

(55.5)

5

(55.5)

0

0

5

(50)

3

(30)

3

(42.8)

4

(40)

2

(50)

0

0

 

0

0

Strept Pyogenes

6

(85.7)

0

2

(22.2)

8

(47.0)

5

(77.7)

0