Conjunctival Fungal Flora in a Tertiary Eye Hospital in Nigeria.

Objectives: The aim of this study is to determine the hospital incidence and pattern of conjunctival fungal flora in adult patients at the Guinness Eye Center Onitsha, Nigeria. Materials and Methods: New adult patients, without anterior segment disease, were randomly recruited. Using a sterile swab stick, specimen was taken from the inferior conjunctival fornix of each participant's right eye and inoculated into Sabouraud dextrose agar slant in a test tube and incubated at 27°C. The specimens were examined for fungal growth every 48 h for 4 weeks. Specimens with fungal growth were further examined under a high power microscope for fungal identification and characterization. Results: A total of 225 patients (105 males, 120 females) were examined. The age range was 18-75 years; mean age was 41 ± 17.1 years; 62 (27.6%) were culture-positive: 25 (40.3%) were males and 37 (59.7%) were females (P >0.05). Both moulds and yeasts were isolated with moulds constituting 44 (74.2%). Aspergillus [26 (41.9%)] and Candida [16 (25.8%)] were the commonest organisms. Participants >60 years had the greatest burden. Pensioners (61.5%), traders (44.0%), farmers (30.1%), and artisans (27.3%) were occupational groups with significantly higher proportions of culture-positive specimens (P < 0.05). Conclusion: Over a quarter of new adult patients without anterior segment disease harbour fungi, some of which are pathogenic, in their conjunctival fungal organisms. While Aspergillus and Candida were the commonest isolates, older participants, pensioners, traders, farmers, and artisans had significantly higher proportion of culture-positive specimens. These findings should be considered when formulating pre-operative guidelines for ocular surgery in our environment.

Peptides in headlock--a novel high-affinity and versatile peptide-binding nanobody for proteomics and microscopy.

Nanobodies are highly valuable tools for numerous bioanalytical and biotechnical applications. Here, we report the characterization of a nanobody that binds a short peptide epitope with extraordinary affinity. Structural analysis reveals an unusual binding mode where the extended peptide becomes part of a ß-sheet structure in the nanobody. This interaction relies on sequence-independent backbone interactions augmented by a small number of specificity-determining side chain contacts. Once bound, the peptide is fastened by two nanobody side chains that clamp it in a headlock fashion. Exploiting this unusual binding mode, we generated a novel nanobody-derived capture and detection system. Matrix-coupled nanobody enables the fast and efficient isolation of epitope-tagged proteins from prokaryotic and eukaryotic expression systems. Additionally, the fluorescently labeled nanobody visualizes subcellular structures in different cellular compartments. The high-affinity-binding and modifiable peptide tag of this system renders it a versatile and robust tool to combine biochemical analysis with microscopic studies.