Sensitivity and Specificity of Confocal Scan in the Diagnosis of Infectious Keratitis

Kanavi, Mozhgan Rezaei; Javadi, Mohammad-Ali; Yazdani, Shahin; Mirdehghanm, Seyedali

doi:10.1097/ico.0b013e318064582d

Cited by 117 publications

(114 citation statements)

References 12 publications

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“…An association with reflective round bodies has been found in up to 85% of cases clinically presenting as Acanthamoeba keratitis (Mathers et al, 1996;Parmar et al, 2006). Sensitivities of around 90 to 100% have been described using confocal microscopy compared with much lower sensitivities of 0 to 50% using culture (Mathers et al, 1996;Parmar et al, 2006;Kanavi et al, 2007;Tu et al, 2008;Vaddavalli et al, 2011). Supporting laboratory evidence is still required as it is not possible to state with certainty if the round structures are definitely Acanthamoeba cysts or trophozoites.…”

Section: Pcr Detectionmentioning

confidence: 99%

Acanthamoeba keratitis: improving the Scottish diagnostic service for the rapid molecular detection of Acanthamoeba species

Alexander

Coyne

Jones

et al. 2015

Journal of Medical Microbiology

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Acanthamoeba species are responsible for causing the potentially sight-threatening condition, Acanthamoeba keratitis, which is commonly associated with contact lens use. In this report, we highlight the challenges faced using conventional laboratory identification methods to identify this often under-reported pathogen, and discuss the reasons for introducing the first national service in Scotland for the rapid and sensitive molecular identification of Acanthamoeba species. By comparing culture and molecular testing data from a total of 63 patients (n580 samples) throughout Scotland presenting with ocular eye disease, we describe the improvement in detection rates where an additional four positive cases were identified using a molecular assay versus culture. The testing of a further ten patients by confocal imaging is also presented. This report emphasizes the importance of continuing to improve clinical laboratory services to ensure a prompt, correct diagnosis and better prognosis, in addition to raising awareness of this potentially debilitating opportunistic pathogen. INTRODUCTIONAcanthamoeba keratitis is an uncommon but sightthreatening disease of the cornea caused by free-living protozoan amoebae belonging to the genus Acanthamoeba (Lorenzo- Morales et al., 2013). This painful, often unilateral eye disease may eventually progress to blindness and is associated with contact lens use but can also be diagnosed in non-contact lens wearers. Acanthamoeba species can be found in a variety of different environments including recreational and drinking water, soil and air (Gianinazzi et al., 2009;Legarreta et al., 2013;Rivera et al., 1991). Trophozoites and highly robust cysts can persist for years and are often resistant to drug treatments.Global increases of Acanthamoeba keratitis occurred during the 1970s and 1980s with links to contact lens use in over 85% of cases, which is consistent with recent data from America and Canada (Stehr-Green et al., 1989;Fraser et al., 2012;Page & Mathers, 2013). In addition, noncommercial saline solutions have been implicated as potential risk factors (Newton et al., 1986). The UK experienced an increase in cases during the 1990s which coincided with increased use of soft contact lenses (Illingworth et al., 1995).There is a lack of recent robust data on the prevalence of Acanthamoeba keratitis in Scotland, but based on a study by Seal et al. (1999), the incidence was 149 per million soft contact lens wearers compared with much lower incidence rates of around 18 to 21 per million in the rest of the UK (Radford et al., 2002). Presently, there are approximately 3.7 million contact lens wearers in the UK (British Contact Lens Association, http://www.bcla.org.uk/).An early, accurate diagnosis is crucial for achieving a better prognosis. However, conventional techniques to detect Acanthamoeba species may lack sensitivity, which is likely to result in the true prevalence being underestimated. The challenges of an early diagnosis are compounded by the ability of Acanthamoeba to mimic non-...

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Section: Pcr Detectionmentioning

confidence: 99%

Acanthamoeba keratitis: improving the Scottish diagnostic service for the rapid molecular detection of Acanthamoeba species

Alexander

Coyne

Jones

et al. 2015

Journal of Medical Microbiology

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“…34 It is particularly valuable when the infective organisms are relatively large (R15 mm). 35 Vaddavalli et al 36 report the distinct confocal microscopic features for Nocardia keratitis as highly reflective, short, and thin branching filaments at the edge of the inflammatory infiltrates.…”

Section: Discussionmentioning

confidence: 99%

Outbreak of Nocardia keratitis after photorefractive keratectomy

Javadi¹,

Kanavi²,

Zarei³

et al. 2009

Journal of Cataract and Refractive Surgery

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Nocardia keratitis occurred in 4 eyes of 3 patients (2 women and 1 man) who had photorefractive keratectomy (PRK) by the same surgeon at the same center. Two eyes of the first 2 patients required lamellar keratectomy to debulk the involved stroma and obtain specimens for microbiological and histopathological evaluation. Light microscopic examination disclosed gram-positive and acid-fast filaments of Nocardia that were confirmed by the microbiological results. Diagnosis of Nocardia keratitis in the third case was not as challenging as in the first 2 cases because of a high index of suspicion. Confocal scans of all cases disclosed hyperreflective and slender, fibril-like structures in the corneal stroma. All eyes responded favorably to topical amikacin and the infection resolved without recurrence. The most probable cause of the outbreak was inadequate attention to sterility during surgery.

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“…Im Vergleich zum mikrobiologischen bzw. histopathologischen Befund wird die Sensitivität und Spezifität mit 100 und 84% für die In-vivo-Darstellung von Akanthamöben, mit 94 und 78 % für die Darstellung von Fungi angegeben [14]. Akanthamöben zeichnen sich in vivo konfokalmikroskopisch durch hyperreflektive doppelwandige Strukturen, Siegelringstrukturen oder hyperreflektive Punkte (Akanthamöbenzysten) oder durch hyperreflektive pleomorphe Schatten mit hyporeflektivem Inhalt, wahrscheinlich Trophozoiten, aus [12,17] (l " Abb.…”

Section: Keratitisunclassified

“…2). Pilzinfektionen zeigen typischerweise Hyphen-ähnliche Strukturen [14]. Hau und Mitarbeiter untersuchten die diagnostische Sicherheit der konfokalen In-vivo-Mikroskopie bei infektiösen Keratitiden und fanden eine eindeutige Abhängigkeit von der Erfahrung des Untersuchers [33].…”

Section: Keratitisunclassified

“…Mit der Zeit hat die konfokale In-vivo-Mikroskopie in der Hornhautdiagnostik zur Abklärung infektiöser Prozesse und zur Evaluierung unklarer Hornhautdystrophien Einzug gehalten [12][13][14][15][16][17][18][19]. Interessante neue Erkenntnisse wurden mithilfe der konfokalen In-vivo-Mikroskopie im Bereich der Wundheilung nach refraktiver Chirurgie [20][21][22][23][24][25], Amniontransplantation [26], penetrierender und lamellärer Keratoplastik [25,27] gewonnen.…”

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Konfokale In-vivo-Mikroskopie - Korrelation zu histologischen Befunden

Messmer

2012

Klin Monatsbl Augenheilkd

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In vivo confocal microcopy is a fascinating technique to obtain rapidly and non-invasively histological/cytological sections of the ocular surface, and observe long-term changes. It allows classification of corneal findings, facilitates the diagnosis of conjunctival lesions, and has broadened our understanding of lid margin disease. To correctly interpret in vivo confocal scans, profound knowledge of microscopic anatomy and histopathology are crucial. To reduce inter-observer variability and allow comparison of scientific studies, in vivo confocal-histopathological correlations have to be investigated, and standards for the interpretation of in vivo confocal microscopic findings must be established. In suspicious lesions of the ocular surface an excisional biopsy and histopathological examination are still the gold standard.

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Sensitivity and Specificity of Confocal Scan in the Diagnosis of Infectious Keratitis

Cited by 117 publications

References 12 publications

Acanthamoeba keratitis: improving the Scottish diagnostic service for the rapid molecular detection of Acanthamoeba species

Acanthamoeba keratitis: improving the Scottish diagnostic service for the rapid molecular detection of Acanthamoeba species

Outbreak of Nocardia keratitis after photorefractive keratectomy

Konfokale In-vivo-Mikroskopie - Korrelation zu histologischen Befunden

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