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Detection of virulence factors in Pseudomonas aeruginosa strains isolated from contact lens-associated corneal ulcers

Pinna, Antonio <1963- > and Usai, Donatella and Sechi, Leonardo Antonio and Molicotti, Paola and Zanetti, Stefania Anna Lucia and Carta, Arturo (2008) Detection of virulence factors in Pseudomonas aeruginosa strains isolated from contact lens-associated corneal ulcers. Cornea, Vol. 27 (3), p. 320-326. eISSN 1536-4798. Article.

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DOI: 10.1097/ICO.0b013e31815c5a3f

Abstract

Purpose: In microbial keratitis associated with contact lens use, Pseudomonas is the most common etiologic agent. The purpose of this study was to report on the microbiological findings of 8 P. aeruginosa strains isolated from contact lens-associated corneal ulcers.
Methods: Scrapings from contact lens-related corneal ulcers were inoculated for culture. Identification and antibiotic susceptibility testing were performed by using the Vitek system (bioMérieux). The Pseudomonas' ability to form biofilm; produce gelatinase, elastase, and alkaline protease; and adhere to and invade human corneal epithelial cells was studied. Polymerase chain reaction with enterobacterial repetitive intergenic consensus primers (ERIC-PCR) was used to establish clonal relationship between the different isolates.
Results: All the strains showed multiple antibiotic resistance (resistance to 4 or more antibiotics), but all were susceptible to aminoglycosides and fluoroquinolones. Biofilm production was weak in 5 cases and absent in the remaining 3 cases. All isolates were able to produce alkaline protease and gelatinase but not elastase. Adherence to human corneal epithelial cells was poor (0-15 bacteria/cell) in 5 cases and medium (16-60 bacteria/cell) in 3 cases. Five isolates were found to be efficient invaders (>1000 CFU/mL). ERIC-PCR showed 8 different genetic patterns.
Conclusions: Because multiresistant Pseudomonas isolates are common, we recommend antibiotic susceptibility testing in all cases of Pseudomonas keratitis so that, if there is no response to initial empiric treatment, antibiotics can be modified according to susceptibility results. The ability to produce alkaline protease and gelatinase and invade the corneal epithelium may play a major role in the pathogenesis of contact lens-related P. aeruginosa keratitis. Also, ERIC-PCR seems to be an inexpensive, fast, reproducible, and discriminatory DNA typing tool for effective epidemiologic surveillance of P. aeruginosa isolates potentially transmissible between patients with ocular infections.

Item Type:Article
ID Code:2850
Status:Published
Refereed:Yes
Uncontrolled Keywords:Contact lens-associated Pseudomonas aeruginosa keratitis, antibiotic susceptibility testing, bacterial exoproteases, biofilm formation, human corneal epithelial cells, polymerase chain reaction with enterobacterial repetitive intergenic consensus primers
Subjects:Area 06 - Scienze mediche > MED/30 Malattie apparato visivo
Area 06 - Scienze mediche > MED/07 Microbiologia e microbiologia clinica
Divisions:001 Università di Sassari > 01 Dipartimenti > Scienze biomediche
001 Università di Sassari > 03 Istituti > Oftalmologia, Otorinolaringoiatria e Urologia
Publisher:Lippincott Williams & Wilkins
eISSN:1536-4798
Deposited On:27 Aug 2009 11:55

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