|Year : 2011 | Volume
| Issue : 3 | Page : 312-313
High oxacillin, vancomycin and fluoroquinolone resistance amongst biofilm forming Staphylococcus aureus isolates from ulcerative keratitis infections
S Singh, R Katiyar, SD Kaistha
Department of Microbiology, CSJM University, Kanpur, Uttar Pradesh, India
|Date of Submission||14-Mar-2011|
|Date of Acceptance||13-Jun-2011|
|Date of Web Publication||17-Aug-2011|
S D Kaistha
Department of Microbiology, CSJM University, Kanpur, Uttar Pradesh
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Singh S, Katiyar R, Kaistha S D. High oxacillin, vancomycin and fluoroquinolone resistance amongst biofilm forming Staphylococcus aureus isolates from ulcerative keratitis infections. Indian J Med Microbiol 2011;29:312-3
|How to cite this URL:|
Singh S, Katiyar R, Kaistha S D. High oxacillin, vancomycin and fluoroquinolone resistance amongst biofilm forming Staphylococcus aureus isolates from ulcerative keratitis infections. Indian J Med Microbiol [serial online] 2011 [cited 2020 Sep 29];29:312-3. Available from: http://www.ijmm.org/text.asp?2011/29/3/312/83921
Increasing antibiotic resistance in Staphylococcus aureus, a leading cause of ulcerative keratitis in the developing world, is of great concern.  Its ability to form biofilms on ocular surfaces enhances antibiotic resistance through several mechanisms.  Understanding of the resistance patterns amongst clinical isolates is a prerequisite for devising better treatment strategies and measures to mitigate emerging antibiotic resistance.
A total of 42 independent Staphylococcus isolates from cases of ulcerative keratitis around Kanpur were evaluated for antibiotic resistance using antibiotic discs (Hi Media, Mumbai, India) as per CLSI guidelines.  The ability of the isolates to form biofilms was characterised using the static microtitre plate assay.  Microbiological and biochemical characterisation of the isolates was performed as per Bergey's determinative bacteriology.  Of these, 75% (30/40) isolates were S. aureus and 23.8% (10/42) were coagulase-negative Staphylococcus epidermis and 4.7% (2/42) were Micrococcus sp.
85.72% (36/42) of the isolates were found to be high biofilm formers and 83% (35/42) were biofilm forming, multiple drug resistant (resistant to three or more classes of antibiotics). Pearson's correlation between biofilm formation and antibiotic resistance was found for S. aureus isolates of 0.6. [Table 1] details the percentage resistance of total and biofilm forming isolates to the various antibiotics. Of the total isolates, 83.3% (35/42) were found to be oxacillin resistant, 57.14% (24/42) were ceftriazone resistant, 54.7% (23/42) were vancomycin resistant and 47.6% (20/42) were tobramycin resistant. It is alarming to note the high percentage of resistance to a number of antibiotics preferentially used for treatment of ocular infections, such as fluoroquinolones. Frequent usage of moxifloxacin in the treatment of ocular infections may be the cause of 76.2% (32/42) resistance to the fourth-generation fluoroquinolone moxifloxacin over ofloxacin (30.9%; 13/42) and levofloxacin (40.4%; 17/42). Low resistance is reported to gentamicin (26.1%; 11/42) which is less frequently used in ocular infections due to problems of poor ocular penetration. Low resistance to extended b lactamase antibiotic imipenem (4.7%; 2/42) is likely a consequence of drug usage only in emergency situations. Judicious use of emerging drugs is advisable as high antibiotic resistance is being measured in biofilm forming, methicillin-resistant S. aureus (MRSA) ocular infections to the most commonly used ophthalmic drugs.
|Table 1: Antibiotic resistance and biofi lm formation in ulcerative keratitis isolates|
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| ~ Acknowledgement|| |
Financial support from DST and DAE, Government of India, is gratefully acknowledged.
| ~ References|| |
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