Key Trials

Introduction

Ocular infections are potentially blinding diseases, and bacteria are the most frequently encountered pathogens affecting ocular structures.

Aim

To provide statistical evidence for the use of antibiotics in ophthalmology by assessing the distribution and antibiotic sensitivity of bacterial isolates from ocular specimens with suspected microbial infections.

Patients Profile

Clinical specimens were obtained from conjunctiva, cornea, aqueous humor, vitreous body, eyelid margin, lacrimal passage, orbital contents, and other ocular sites in the Inpatient Wards and Outpatient Clinics

Methods

• Retrospective analysis
• 11 530 ocular specimens with suspected microbial infections were submitted for microbiological evaluation
• The parameters assessed mainly included
  
  • distribution of isolated bacteria  
  • results of susceptibility tests for antibiotics.

• In the analysis of antibiotic sensitivities, the bacteria were divided into four groups according to gram staining, and statistical methods were used to compare their antibiotic sensitivities.

Results

• Among a total of 11 530 specimens
  
  • 3625 (31.44%) showed bacterial growth, and 3690 bacterial strains were isolated
• Among 3625 bacterial specimens

• 2849 (78.59%) were obtained from the conjunctiva
•  569 (15.70%) from the cornea
•  111 (3.06%) from the aqueous humor or vitreous body
• 96 (2.65%) from the lacrimal passage, eyelid margin, orbital contents and other ocular sites

• A total of 3690 bacterial strains (32 genera and 140 species) were isolated           
• G+C (82.30%) were prominent in the total bacterial isolates (Figure 1)
• Staphylococcus epidermidis (54.39%) was the predominant bacterial isolate followed by Staphylococcus aureus (7.05%), C. xerosis (4.34%), Staphylococcus hominis (3.39%), Staphylococcus haemolyticus (3.12%), and P. aeruginosa (2.09%). (Table 1).

• The sensitivity rate of the total isolates to gatifloxacin was up to 90.01%, with G+C, G+B, G-C, and G-B being all highly sensitive
  
  • These finding indicated that gatifloxacin is a broad-spectrum antibiotic with high sensitivity and is suitable for topical prophylactic use in ophthalmology
• The sensitivity rate of the total isolates to levofloxacin was low (51.91%), whereas that of G-B was high (83.66%)
• The sensitivity rates of G+C and G+B to vancomycin were significantly higher than those of G-C and G-B (P<0.05)

• For fusidic acid, the sensitivity rates of G+C (89.83%) and G+B (73.37%) were significantly higher than that of G-B (29.83%; P<0.05)
• The gram-negative bacteria’s sensitivity rate to cefuroxime was as low as 59.25%, but only G-B was less sensitive to cefuroxime (57.28%), while G-C was still highly sensitive (89.29%)
• The sensitivity rate of gram-positive bacteria to moxifloxacin was as high as 80.28%, but only G+C was highly sensitive to moxifloxacin (81.21%), while G+B was still less sensitive (32.00%)

Any sensitivity rate with a denominator number less than 15 was not included in this statistical analysis. TGC: Tigecycline; VAN: Vancomycin; RIF: Rifampicin; GAT: Gatifloxacin; CXM: Cefuroxime; FDA: Fusidic acid; CAZ: Ceftazidime; AMK: Amikacin; MFX: Moxifloxacin; OFX: Ofloxacin; GEN: Gentamicin; TOB: Tobramycin; LVX: Levofloxacin; CIP: Ciprofloxacin. “A>B, C” means the sensitivity of A was significantly higher than that of B and C (P<0.05), and no statistically significant difference was noted in the sensitivity of B and C (P>0.05).

Conclusion

• This 5-year study found that S. epidermidis was the main isolate of all ocular specimens with bacteria
• As a broad-spectrum antibiotic with high sensitivity, gatifloxacin is more suitable than levofloxacin for topical prophylactic use in ophthalmology, and levofloxacin is an effective drug for treating G-B
• Vancomycin and fusidic acid both have better effects on gram-positive bacteria than gram-negative bacteria
• These findings may help ophthalmologists make more appropriate decisions for the treatment of ocular bacterial infections

Reference

Int J Ophthalmol 2020;13(1):54-60