Related Experiment Video
Updated: May 31, 2026

Intravitreal Injection and Quantitation of Infection Parameters in a Mouse Model of Bacterial Endophthalmitis
Published on: February 6, 2021
Extended-spectrum beta-lactamase-mediated resistance among bacterial isolates recovered from ocular infections
M Jayahar Bharathi1, R Ramakrishnan, S Ramesh
1Department of Microbiology and Molecular Biology, Aravind Eye Hospital and Postgraduate Institute of Ophthalmology, Tirunelveli, Tamil Nadu, India. jayahar@tvl.aravind.org
Purpose:
To evaluate resistances mediated by extended-spectrum β-lactamases (ESBLs) and AmpC β-lactamases among Gram-negative bacteria recovered from ocular infections.
Methods:
As per the Clinical Laboratory Standards Institute M100-S-16 document, a total of 135 Gram-negative bacilli were recovered from ocular specimens and were subjected to phenotypic confirmation for ESBL production by the double-disc synergy test, cephalosporin and clavulanate combination disc test and E test, and, for AmpC β-lactamase, the modified double-disc approximation method and AmpC disc test.
Results:
In the double-disc synergy test, 21 (15.5%) isolates showed positive results against the cefpodoxime disc, 19 (14%) against cefpodoxime and cefotaxime, 15 (11%) against cefpodoxime, cefotaxime and ceftriaxone and 10 (7%) isolates were against cefpodoxime, cefotaxime, ceftriaxone and ceftazidime discs. In the cephalosporin/clavulanate combination disc test, 19 (14%) isolates showed positive results against cefotaxime with clavulanic acid and 10 (7%) isolates against ceftazidime with clavulanic acid. In the E test, 10 (7%) isolates displayed positive results against ceftazidime and 19 (14%) against cefotaxime. In the AmpC disc test for phenotypic confirmation, indentations were observed in 15 (11%) isolates with flattening also occurring in 10 (7%) isolates.
Conclusion:
The incidences of ESBL- and AmpC β-lactamase-mediated resistances are found to be 7 and 18.5% among ocular isolates, respectively, and are more prevalent among the strains of Escherichia coli and Klebsiella pneumoniae.
Related Concept Videos
Clinical Significance of Antibiotic Resistance
Microbiome of the Eye
Mechanism of Antibiotic Resistance in MRSA
Development of Antibiotic Resistance
Inhibitors of Gram-positive Cell Wall Synthesis
Defense Against Bacterial Pathogens
Phagocytes
Phagocytes are the frontline soldiers of the immune system. They include neutrophils and macrophages. Neutrophils are the most abundant type of white blood cell and are quickly mobilized to the site of infection. Macrophages are larger cells that patrol...

