c.i.-fluorescent-brightening-agent-28 and Keratitis

The incidence of fungal keratitis demonstrates significant geographic and climatic variation. We report on the characteristics of the potassium hydroxide/calcofluor white (KOH-CFW) preparation observed at a tertiary center in Northern California, a region with a low incidence of fungal keratitis.. Culture-proven cases of microbial keratitis during a 5-year period were retrospectively reviewed. The sensitivity, specificity, and posttest probabilities were determined for the KOH-CFW assay. These results were compared with documented clinical impression and values reported in the literature.. Three hundred three of 368 episodes of microbial keratitis during the study period documented the results of a fungal culture, KOH-CFW assay, and a clinical impression. Twenty-one (6.9%) of these cultures were positive for fungal organisms. The sensitivity and specificity of the KOH-CFW test were 29% and 93%, respectively. Clinicians' initial clinical impression based solely on patients' history and examination, without the aid of any histopathologic or biochemical test results, demonstrated a sensitivity and specificity of 33% and 89%, respectively.. The observed sensitivity and specificity of the KOH-CFW preparation are significantly lower than many previously reported values. In regions with low incidence of fungal keratitis, the KOH-CFW preparation may have diagnostic performance similar to that of the clinical impression formed only on the basis of history and physical examination.

Topics: Adolescent; Adult; Aged; Aged, 80 and over; Benzenesulfonates; California; Child; Child, Preschool; Cornea; Eye Infections, Fungal; Female; Fluorescent Dyes; Follow-Up Studies; Fungi; Humans; Hydroxides; Incidence; Indicators and Reagents; Infant; Infant, Newborn; Keratitis; Male; Microscopy, Fluorescence; Middle Aged; Potassium Compounds; Reproducibility of Results; Retrospective Studies; Young Adult

To assess the sensitivity of potassium hydroxide and calcofluor white (KOH+CFW) mount in the diagnosis of Pythium keratitis and concordance among microbiologists.. Three microbiologists evaluated the microscopic images of KOH + CFW mounts of confirmed cases of Pythium and fungal keratitis seen between January 2019 and February 2021. The filaments were compared using specific differentiating features. The sensitivity and specificity of KOH + CFW in diagnosing Pythium infection were evaluated along with concordance among the microbiologists.. Sixty consecutive cases with confirmed growth of fungus or Pythium insidiosum (n = 29) were evaluated. The sensitivity of KOH + CFW in the correct identification of Pythium filaments ranged from 79.3% to 96.5% among three microbiologists. There was good interobserver (k = 0.76-0.90) and intraobserver (k = 0.70-0.97) agreements among three microbiologists. The differentiating findings (P < 0.0001) suggestive of Pythium filaments were the absence of septae in 23 (79.3%) and collapsed walls in 22 (75.9%) cases.. KOH + CFW has good sensitivity and specificity in the diagnosis of Pythium keratitis with good interobserver and intraobserver concordance.

Topics: Benzenesulfonates; Coloring Agents; Cornea; Eye Infections, Fungal; Fungi; Humans; Hydroxides; Keratitis; Potassium Compounds; Pythium

Topics: Benzenesulfonates; Coloring Agents; Humans; Hydroxides; Keratitis; Potassium Compounds; Pythium

Topics: Benzenesulfonates; Coloring Agents; Humans; Hydroxides; Keratitis; Potassium Compounds; Pythium

To evaluate the efficacy of trypan blue in direct microscopic examination of corneal scrapings in the diagnosis of non-viral microbial keratitis.. In a prospective, interventional, masked study, 82 consecutive patients were investigated. Direct microscopic examination of the corneal scrapings involved three smears stained with potassium hydroxide with calcofluor white (KOH + CFW), Gram stain (not analyzed), and trypan blue stain and culture for bacteria, fungus, and Acanthamoeba. While KOH + CFW stained slides were examined under a fluorescence microscope, trypan blue-stained slides were examined by two microbiologists (masked to KOH + CFW and culture results) under normal light microscopy. Thirty samples were reexamined for interobserver and intraobserver variability.. Out of 82 samples, fungal/fungus-like elements were seen in 48 (58.5%) in KOH + CFW and 38 (46.3%) in trypan blue stain. One microsporidial case, detected in KOH + CFW was negative in trypan blue stain (culture not done). Fungal growth was positive in 23 out of 81 (28.3%) cases cultured, single bacterial species in 18 (22.2%), Pythium insidiosum in three, mixed bacteria and fungus/Pythium in 7 (8.6%), Acanthamoeba in none and 30 (37.0%) samples were sterile. With culture as gold standard, the respective sensitivity (84.9%, 75.7%) and specificity (90.9%, 68.2%) of KOH + CFW stain and trypan blue stain were comparable (p = 0.16, P = 0.06). The interobserver linear weighted kappa score between the two microbiologists was 1.00 while it was 0.86 for intraobserver agreement.. Trypan blue stain, an easily available dye to ophthalmologists, is highly efficacious in the diagnosis of fungal keratitis.

Topics: Benzenesulfonates; Cornea; Humans; Hydroxides; Keratitis; Microscopy, Fluorescence; Potassium Compounds; Prospective Studies; Trypan Blue

Acanthamoeba cysts are resistant to unfavorable physiological conditions and various disinfectants. Acanthamoeba cysts have 2 walls containing various sugar moieties, and in particular, one third of the inner wall is composed of cellulose. In this study, it has been shown that down-regulation of cellulose synthase by small interfering RNA (siRNA) significantly inhibits the formation of mature Acanthamoeba castellanii cysts. Calcofluor white staining and transmission electron microscopy revealed that siRNA transfected amoeba failed to form an inner wall during encystation and thus are likely to be more vulnerable. In addition, the expression of xylose isomerase, which is involved in cyst wall formation, was not altered in cellulose synthase down-regulated amoeba, indicating that cellulose synthase is a crucial factor for inner wall formation by Acanthamoeba during encystation.

Topics: Acanthamoeba castellanii; Aldose-Ketose Isomerases; Amebiasis; Benzenesulfonates; Cell Wall; Cellulose; Down-Regulation; Encephalitis; Glucosyltransferases; Keratitis; Microscopy, Electron, Transmission; RNA Interference; RNA, Small Interfering

The aim of this study was to develop a quick and economical method for the diagnosis of fungal keratitis. Corneal scrapings were obtained from consecutive patients (n = 165) with clinically suspected fungal keratitis and were used for culture and to prepare two smears. Potassium hydroxide stain followed by calcofluor white stain was added to one smear and Giemsa stain followed by calcofluor white stain was added to the second. In comparison with the fungal culture results, the sensitivity of potassium hydroxide wet mounts was 81.0% and following the addition of calcofluor white was 96.6% in diagnosing fungal keratitis, whereas sensitivity using Giemsa stain was 39.7% and following the addition of calcofluor white was 98.3%. The Giemsa stain detected 23 cases of bacterial infection, of which six cases were mixed fungal and bacterial infections. Giemsa stain followed by calcofluor white was considered to be the better method for diagnosing fungal keratitis due to its high sensitivity combined with its ability to identify bacterial or mixed infections.

Topics: Azure Stains; Benzenesulfonates; Cornea; Eye Infections, Fungal; Humans; Hydroxides; Keratitis; Microscopy; Potassium Compounds; Staining and Labeling

Retrospective evaluation of potassium hydroxide plus calcofluor white (KOH+CFW), Gram, Giemsa, and modified Ziehl-Neelsen (1% H(2)SO(4), cold) stains for the detection of microsporidia in corneal scrapings from 30 patients showed KOH+CFW and acid-fast stains to be most efficient (29/30 [96.7%] and 28/30 [93.3%], respectively) in the diagnosis of microsporidial keratitis.

Topics: Benzenesulfonates; Cornea; Eye Infections, Parasitic; Humans; Hydroxides; Keratitis; Microsporidia; Microsporidiosis; Potassium Compounds; Specimen Handling; Staining and Labeling

Calcofluor white (CFW) is a chemofluorescent dye with an affinity for the polysaccharide polymers of amebic cysts. Using CFW staining with fluorescent microscopy, we demonstrated amebic cysts in corneal scrapings and keratectomy specimens from four patients with culture-proved Acanthamoeba keratitis and from one in whom CFW was the only positive laboratory test. Calcofluor white staining is simple, rapid, and highly reliable in the diagnosis of Acanthamoeba keratitis.

Topics: Adolescent; Adult; Amebiasis; Amoeba; Benzenesulfonates; Cornea; Female; Fluorescent Dyes; Humans; Keratitis; Male; Middle Aged; Staining and Labeling

Calcofluor and ink-potassium hydroxide preparations identified Fusarium solani, Aspergillus fumigatus, and Candida albicans, the three most common ocular fungal pathogens, in scrapings, biopsy specimens, and tissue sections of corneal mycotic infections in rabbits. These stains also identified fungal organisms in specimens from four human patients with keratomycoses. Neither procedure requires more than a few minutes to perform or extensive training or experience to interpret. The specimen stained with calcofluor can be examined immediately, but may not identify all fungi. The more sensitive ink-potassium hydroxide preparation should be examined after 18 to 24 hours, and is less likely to provide false-positive results than the calcofluor method.

Topics: Animals; Benzenesulfonates; Contrast Media; Eye Diseases; Hydroxides; Ink; Keratitis; Mycoses; Potassium; Potassium Compounds; Rabbits