PANEL 3: Otitis media animal models, cell culture, tissue regeneration & pathophysiology

OBJECTIVE

To review and summarize recently published key articles on the topics of animal models, cell culture studies, tissue biomedical engineering and regeneration, and new models in relation to otitis media (OM).

DATA SOURCE

Electronic databases: PubMed, National Library of Medicine, Ovid Medline.

REVIEW METHODS

Key topics were assigned to the panel participants for identification and detailed evaluation. The PubMed reviews were focused on the period from June 2019 to June 2023, in any of the objective subject(s) or keywords listed above, noting the relevant references relating to these advances with a global overview and noting areas of recommendation(s). The final manuscript was prepared with input from all panel members.

CONCLUSIONS

In conclusion, ex vivo and in vivo OM research models have seen great advancements in the past 4 years. From the usage of novel genetic and molecular tools to the refinement of in vivo inducible and spontaneous mouse models, to the introduction of a wide array of reliable middle ear epithelium (MEE) cell culture systems, the next five years are likely to experience exponential growth in OM pathophysiology discoveries. Moreover, advances in these systems will predictably facilitate rapid means for novel molecular therapeutic studies.

Microbial contamination of tattoo and permanent makeup inks marketed in the US: a follow-up study

In a 2018 survey, U.S. Food and Drug Administration (FDA) identified microbial contamination in 42 (49%) of 85 unopened tattoo and permanent makeup (PMU) inks purchased from 13 manufacturers in the US between November 2015 and April 2016. To confirm the results of our previous survey, we evaluated the level of microbial contamination in an additional 27 samples from 10 manufacturers from September 2017 to December 2017, including 21 unopened tattoo and PMU inks which were selected based on our previous survey results and 6 ink diluents that were not previously analysed. Aerobic plate count and enrichment culture methods from the FDA's Bacteriological Analytical Manual revealed 11 (52%) out of 21 inks, from six manufacturers, were contaminated with micro-organisms, with contamination levels up to 3·6 × 10⁸  CFU per gram, consistent with our previous survey results. We identified 25 bacterial strains belonging to nine genera and 19 species. Strains of Bacillus sp. (11 strains, 44%) were dominant, followed by Paenibacillus sp. (5 strains, 20%). Clinically relevant strains, such as Kocuria rhizophila and Oligella ureolytica, were also identified, as similar to the findings in our previous survey. No microbial contamination was detected in any of the six ink diluents.

Enhancement of immune response against Bordetella spp. by disrupting immunomodulation

Well-adapted pathogens must evade clearance by the host immune system and the study of how they do this has revealed myriad complex strategies and mechanisms. Classical bordetellae are very closely related subspecies that are known to modulate adaptive immunity in a variety of ways, permitting them to either persist for life or repeatedly infect the same host. Exploring the hypothesis that exposure to immune cells would cause bordetellae to induce expression of important immunomodulatory mechanisms, we identified a putative regulator of an immunomodulatory pathway. The deletion of btrS in B. bronchiseptica did not affect colonization or initial growth in the respiratory tract of mice, its natural host, but did increase activation of the inflammasome pathway, and recruitment of inflammatory cells. The mutant lacking btrS recruited many more B and T cells into the lungs, where they rapidly formed highly organized and distinctive Bronchial Associated Lymphoid Tissue (BALT) not induced by any wild type Bordetella species, and a much more rapid and strong antibody response than observed with any of these species. Immunity induced by the mutant was measurably more robust in all respiratory organs, providing completely sterilizing immunity that protected against challenge infections for many months. Moreover, the mutant induced sterilizing immunity against infection with other classical bordetellae, including B. pertussis and B. parapertussis, something the current vaccines do not provide. These findings reveal profound immunomodulation by bordetellae and demonstrate that by disrupting it much more robust protective immunity can be generated, providing a pathway to greatly improve vaccines and preventive treatments against these important pathogens.

FDA 2014 survey of eye area cosmetics for microbiological safety

In an attempt to assess cosmetics containing 'nontraditional' preservatives, 93 eye area cosmetic products were selected based on labelled or marketed claims that these products were 'green', 'natural', 'paraben-free', 'preservative-free' or contained nontraditional preservatives (e.g. botanical extracts). Products were analysed for water activity, pH and microbiological content, which included enumeration of aerobic micro-organisms, detection of microbial growth after a 7-day enrichment and identification of microbial isolates. The survey found that 60% (56/93) of the eye area cosmetics were free of microbiological growth under test conditions, 32% (30/93) showed the presence of micro-organisms at low levels (<100 CFU per ml or g) and 8% (7/93) showed microbiological growth at higher levels (> 100 CFU per ml or g). Gram-positive bacteria such as Bacillus and Staphylococcus were the dominant genera identified in these cosmetic products, whereas Gram-negative species were relatively uncommon. The survey found a positive association between lower water activity cosmetics and the presence of micro-organisms in these products. Similarly, colour cosmetics were more likely to contain micro-organisms than noncolour cosmetics. The most represented micro-organisms in the survey were from genus Bacillus, suggesting that the natural raw materials are the likely source of observed microbial loads.

SIGNIFICANCE AND IMPACT OF THE STUDY

In the United States, cosmetic products are regulated postmarket; therefore, surveillance programmes are one of FDA's most important tools for monitoring microbiological safety of cosmetics. 'Traditional' preservatives, such as parabens and formaldehyde releasers, are perceived unfavourably by some consumers, resulting in cosmetic manufacturers increasingly using 'nontraditional' preservatives. FDA conducted an analytical survey of eye area cosmetics that claimed to be free of traditional preservatives and determined microbiological loads in tested products. This study explores the association of microbial loads with the physical and chemical characteristics of the cosmetic products, and points to the limits of preservative activity in cosmetics.

Preoperative urine culture is unnecessary in asymptomatic men prior to prostate needle biopsy

PURPOSE

To determine the clinical utility of preoperative urine cultures in asymptomatic men undergoing prostate needle biopsy (PNB).

METHODS

One hundred fifty asymptomatic men had urine cultures obtained 14-days prior to PNB. As per study protocol, positive cultures were not treated. Antibiotic prophylaxis prior to PNB included ciprofloxacin 500 mg the night before and morning of the biopsy. Repeat urine cultures were obtained immediately prior to PNB with colony-forming units (CFUs) annotated. Infectious complications post-biopsy were recorded.

RESULTS

Of the 150 men, six patients (4%) had evidence of asymptomatic bacteriuria with > 10,000 CFU/mL on office urine culture. Repeat urine cultures on morning of biopsy in all 150 patients noted a mean bacterial count of 55 CFU/mL (range 0-1000). All six patients with positive office urine cultures had < 100 CFU/mL at time of PNB. Following biopsy, four patients (2.7%) developed an infectious complication including two with sepsis and two with culture-positive UTIs. The causative organism in all cases was quinolone-resistant E. coli. None of the six patients with preoperative positive urine cultures developed an infectious complication following PNB.

CONCLUSIONS

In this prospective observational study, under 5% of asymptomatic men had positive office cultures prior to PNB. Furthermore, repeat urine culture on the morning of biopsy showed resolution in these patients, and none developed post-biopsy infectious complications. Routine office urine culture in the asymptomatic male prior to PNB was unnecessary.

Procedural povidone iodine rectal preparation reduces bacteriuria and bacteremia following prostate needle biopsy

INTRODUCTION

To determine if a povidone iodine rectal preparation (PIRP) reduces rates of bacteriuria and bacteremia following transrectal ultrasound guided prostate needle biopsy (TRUS PNB).

MATERIALS AND METHODS

Men undergoing TRUS PNB were prospectively enrolled in a study comparing the impact of PIRP versus standard of care (two pills of ciprofloxacin 500 mg). Urine, blood, and rectal cultures were obtained 30 minutes post-procedure with colony forming units (CFUs) determined after 48 hours. Patients were called 7 and 30 days post-procedure to evaluate for infections.

RESULTS

A total of 150 men were accrued into this study including 95 receiving PIRP and 55 the standard of care. Two-thirds of patients were undergoing an initial biopsy, 19% used antibiotics within the previous 6 months, and median number of biopsy cores was 14. There were no differences between the two cohorts with respect to baseline or biopsy characteristics. In the PIRP cohort, rectal cultures before and after PIRP administration noted a 97.2% reduction in microorganism colonies (2.4 x 10 5 CFU/mL versus 6.7 x 10³CFU/mL, p < 0.001). Mean urine bacterial counts following TRUS PNB were 1 CFU/mL for PIRP versus 7 CFU/mL for standard cohort (p < 0.001). Mean serum bacterial counts following TRUS PNB were 0 CFU/mL for PIRP versus 3 CFU/mL for standard of care (p = 0.01). One patient in the PIRP cohort (1.1%) developed post-biopsy sepsis while 3 (5.5%) in the standard cohort had an infectious complication (1 UTI, 2 sepsis).

CONCLUSION

A PIRP regimen reduced bacteruria and bacteremia following TRUS PNB.

Povidone Iodine Rectal Preparation at Time of Prostate Needle Biopsy is a Simple and Reproducible Means to Reduce Risk of Procedural Infection

Single institution and population-based studies highlight that infectious complications following transrectal ultrasound guided prostate needle biopsy (TRUS PNB) are increasing. Such infections are largely attributable to quinolone resistant microorganisms which colonize the rectal vault and are translocated into the bloodstream during the biopsy procedure. A povidone iodine rectal preparation (PIRP) at time of biopsy is a simple, reproducible method to reduce rectal microorganism colony counts and therefore resultant infections following TRUS PNB. All patients are administered three days of oral antibiotic therapy prior to biopsy. The PIRP technique involves initially positioning the patient in the standard manner for a TRUS PNB. Following digital rectal examination, 15 ml of a 10% solution of commercially available povidone iodine is mixed with 5 ml of 1% lidocaine jelly to create slurry. A 4 cmx4 cm sterile gauze is soaked in this slurry and then inserted into the rectal vault for 2 min after which it is removed. Thereafter, a disposable cotton gynecologic swab is used to paint both the perianal area and the rectal vault to a distance of 3 cm from the anus. The povidone iodine solution is then allowed to dry for 2-3 min prior to proceeding with standard transrectal ultrasonography and subsequent biopsy. This PIRP technique has been in practice at our institution since March of 2012 with an associated reduction of post-biopsy infections from 4.3% to 0.6% (p=0.02). The principal advantage of this prophylaxis regimen is its simplicity and reproducibility with use of an easily available, inexpensive agent to reduce infections. Furthermore, the technique avoids exposing patients to additional systemic antibiotics with potential further propagation of multi-drug resistant organisms. Usage of PIRP at TRUS PNB, however, is not applicable for patients with iodine or shellfish allergies.

Maintaining a high level of suspicion for recurrent malignant disease: report of a case with periapical involvement

AIM

To report the unusual endodontic presentation and radiographic features of a subgroup of pleomorphic adenoma called carcinoma ex pleomorphic adenoma and to stress the importance of maintaining a high level of suspicion in cases where primary or recurrent neoplasia is included in the differential diagnosis.

SUMMARY

This paper describes a case in which a patient with a previous history of malignant neoplasm presented with signs and symptoms similar to a dental infection. The pathology report however confirmed recurrence of the previous tumour in a malignant fashion. The importance of maintaining a high level of suspicion in early management of such disease is highlighted.

KEY LEARNING POINTS

*Pleomorphic adenomas, also known as benign mixed tumours, are common salivary gland tumours, which infrequently undergo malignant transformation, with potentially devastating consequences. *Malignant salivary gland tumours can present as dental swelling, dental pain and sudden loss of vitality of teeth so both general practitioners and specialists have the responsibility to evaluate such patients with a broad vision. *Radiographic differential diagnosis of periapical radiolucency should also include malignant salivary gland tumours. *This case highlights the need of vigilance at all times and emphasizes the benefits of biopsy and histological examination in the diagnosis of recurrent malignant salivary gland tumours.

Novel peptides of therapeutic promise from Indian Conidae

Highly structured small peptides are the major toxic constituents of the venom of cone snails, a family of widely distributed predatory marine molluscs. These animals use the venom for rapid prey immobilization. The peptide components in the venom target a wide variety of membrane-bound ion channels and receptors. Many have been found to be highly selective for a diverse range of mammalian ion channels and receptors associated with pain-signaling pathways. Their small size, structural stability, and target specificity make them attractive pharmacologic agents. A select number of laboratories mainly from the United States, Europe, Australia, Israel, and China have been engaged in intense drug discovery programs based on peptides from a few snail species. Coastal India has an estimated 20-30% of the known cone species; however, few serious studies have been reported so far. We have begun a comprehensive program for the identification and characterization of peptides from cone snails found in Indian Coastal waters. This presentation reviews our progress over the last 2 years. As expected from the evolutionary history of these venom components, our search has yielded novel peptides of therapeutic promise from the new species that we have studied.