Screening of OcularEnterobacteriaceaeIsolates for Presence of ChromosomalblaNDM-1and ESBL Genes: A 2-Year Study at a Tertiary Eye Care Center

Abstract

PURPOSE. Since, to our knowledge, there are no reports on the prevalence of the blaNDM-1 gene among ocular isolates of Enterobacteriaceae, and only limited information on the prevalence of extended spectrum beta-lactamases (ESBLs) among ocular bacterial isolates are available, our study was undertaken. METHODS.A prospective study was done on 74 Enterobacteriaceae isolates from patients presenting with clinical suspicion of bacterial ocular infections during a period from January 2010-December 2011. All isolates were subjected to detection of ESBLs by double disc synergy and screened for the presence of CTX-M -I, II, III, and IV groups, and OXA, TEM, SHV, blaNDM-1 genes by PCR. RESULTS.Of 74 ocular Enterobacteriaceae isolates 57 (77%) were ESBL producers tested by the double disc diffusion test. PCR-based DNA sequencing of these 57 ocular isolates showed the presence of CTX-M-15 (14.0%), blaOXA-1 (5.2%), blaSHV-1 (8.7%), and blaTEM-1 (7.0%) types. The blaNDM-1 was absent among these ocular isolates. The most widely disseminated ESBL gene among ocular isolates was CTX-M-15. Phenotypic and genotypic results showed 100% correlation.CONCLUSIONS. To our knowledge, this is the first extensive study performed to genotype ESBL-producing ocular Enterobacteriaceae isolates. The isolation of ESBL-producing Enterobacteriaceae organisms predominantly from conjunctival specimens indicates community-acquired infections/colonization by these bacteria in the conjunctiva of the patients, and cases are not related to hospital-acquired infections because of the short stay of ophthalmic patients in the hospitals. A shift in the resistance rates of ceftazidime from 37.5% to 79.7% over the years proves the increase in drug resistance among ocular clinical isolates. (Invest Ophthalmol Vis Sci. 2012;53:5251-5257)

Identification and Characterization of the First Escherichia coli Strain Carrying NDM-1 Gene in China

“…Group I includes CTX-M-1, -3, -10 to -12, -15, -22, -23, -28, -29, etc. CTX-M-57 is a group I CTX-M and shared 99% amino acid identity with CTX-M-15[21], [22], which is one of the most common types of ESBL found in bacterial isolates[23]. The sequences of the bla NDM-1 , bla TEM , and bla CTX-M-57 genes were analyzed and deposited in GenBank under accession numbers HQ603057, JX036279, and JX036278.…”

Application of six multiplex PCR's among 200 clinical isolates of Pseudomonas aeruginosa for the detection of 20 drug resistance encoding genes

“…Clinical isolates were mainly from ocular specimens such as corneal scraping, corneal button, conjunctival swab, conjunctival scraping, vitreous humor, aqueous chamber tap, contact lens, infective suture, Intraocular lens (IOL), Iris tissue, lacrimal sac, eviscerated material, canalicular pus, cassette of vitrectomy, scleral scraping, Donor Cornel rim (DCR), Donor conjunctival swab and other samples such as wound swab, blood, urine, rectal swab, lung tissue fluid. Further identification and antibiotic susceptibility tests, phenotypic detection of ESBL, MBL and efflux pump were carried out as per our previous reports [15,16,19]. DNA extracted from pure culture were stored at −20 °c for short storage and kept at −80 °c for long storage.…”

“…We designed primers for the selected genes found to be most prevalent among clinical studies as well as our own observation from NGS based study and other reports [12–21]. Multiplex PCR Primer designed against drug resistance gene include Group‐1; (ESBL‐MBL) blaTem, blaOXA, blaCTX‐M‐15, blaVim) Group‐2, (blaGes, blaVeb and DIM and AmpC) Efflux pump genes‐ Group‐3 (MexA,B‐oprM); Group‐4 (MexC,D‐oprJ); Group‐5 (Mex X,Y‐oprN) Group‐6 (oprD, nfxB, MexR) primers were purchased from Eurofins Genomics India Pvt Ltd, Bangalore, India.…”

Characterization of antibiotic resistance profiles of ocular Enterobacteriaceae isolates

“…All PCR positive amplified products were subjected to DNA sequencing with the primers of the corresponding genes, and the results were analyzed as described earlier [ 8 ].…”

“…Extensive studies on the resistance pattern of systemic multidrug resistant isolates which were FQ-resistant and ESBL producers exist, but similar studies in ocular isolates are limited [ 7 ]. Interestingly, infections caused by ESBL-producing, quinolone-resistant isolates are increasing in higher frequency among the ocular isolates [ 8 ]. Understanding the susceptibility pattern of ESBL-producing and carbapenemase-producing ocular Enterobacteriaceae isolates and their genotypic prevalence is, therefore, vital.…”