736 Endoscopic-Guided Decompression of an Incidental, Massive, Infected Fronto-Ethmoidal Mucocele: Our Experience

A 55-year-old man was referred to neurology with worsening headaches and right-hand numbness. An MRI brain demonstrated a hemangioblastoma but also a large right sided frontoethmoidal mucocele. The only sino-nasal symptom the patient had was unilateral nasal obstruction but felt this was well-controlled with a steroid nasal spray prescribed in primary care. Nasendoscopy showed pus emanating from a smooth mass anterior in the nasal cavity. A CT scan showed features of a large, expansile mass extending across both frontal and ethmoid sinuses, lateralising the septum, with dehiscence of the lamina papyracea. The patient underwent image-guided endoscopic sinus surgery to drain the mucocele which was filled with a considerable amount of pus and was seen to have eroded all sinus lamellae. Sinonasal mucoceles are expansile collections of mucous, lined with epithelium, and are thought to be more common in the third and fourth decades (1). They are usually caused by sinus surgery as a result of an obstructed sinuses but can follow trauma, inflammation or occur spontaneously (2). Once identified, surgery is the standard of care to prevent complications from expansion or infection. In this case report, along with imaging and intraoperative photographs, we further describe our approach and experience in managing a large mucocele.

The antibacterial activity and modes of LI-F type antimicrobial peptides against Bacillus cereus in vitro

AIMS

LI-Fs are a family of highly potent cyclic lipodepsipeptide antibiotics with a broad antimicrobial spectrum (Gram-positive bacteria and fungi). In this study, LI-F-type antimicrobial peptides (AMP-jsa9) composing of LI-F03a, LI-F03b, LI-F04a, LI-F04b and LI-F05b were isolated from Paenibacillus polymyxa JSA-9. To better understand the antimicrobial mechanism of AMP-jsa9, the potency and action(s) of AMP-jsa9 against Bacillus cereus were examined.

METHODS AND RESULTS

Flow cytometry, confocal laser microscopy, scanning electron microscopy, transmission electron microscopy (TEM) and atomic force microscopy observation, as well as determination of peptidoglycan and cell wall-associated protein and other methods were used. The results indicate that AMP-jsa9 exhibits strong, broad-spectrum antimicrobial activity. Moreover, AMP-jsa9 targets the cell wall and membrane of B. cereus to impair membrane integrity, increase membrane permeability and enhance cytoplasm leakage (e.g. K⁺ , protein, nucleic acid). This leads to bacterial cells with irregular, withered and coarse surfaces. In addition, AMP-jsa9 is also able to bind to DNA and break down B. cereus biofilms.

CONCLUSIONS

In this study, the action mechanism of LI-Fs against B. cereus was clarified in details.

SIGNIFICANCE AND IMPACT OF THE STUDY

The results of this study provide a theoretical basis for utilizing AMP-jsa9 or similar analogues as natural and effective preservatives in the food and feed industries. These efforts could also stimulate research activities interested in understanding the specific effects of other antimicrobial agents.