Renāta Vīksne (Klagiša)

A retrospective cohort study was conducted with the aim to characterise tonsillectomy patients and identify factors related to the development of complicated cases of tonsillitis and consecutive immediate tonsillectomies in the Latvian population. The data of 493 patients were analysed. Patients were hospitalised from 1 January 2019 to 30 November 2020, for elective or immediate tonsillectomy due to recurrent tonsillitis, with or without exacerbation and complications. The patients who underwent elective tonsillectomy were younger than those who underwent immediate tonsil-lectomy. Peritonsillar abscess was more common in smokers than in non-smokers ( p < 0.001). Smokers had immediate tonsillectomy more often than non-smokers ( p < 0.001). Patients who underwent elective tonsillectomy had the shortest period of antibiotic therapy ( p < 0.001). Patients who had immediate tonsillectomy had a longer hospitalisation time. Immediate tonsillectomies were associated with patients of older age, smokers, longer hospitalisation, and antibacterial treatment periods. Unilateral peritonsillar abscess was the most common complication of tonsillitis, which resulted in immediate tonsillectomy.

After nasopharyngitis and otitis media tonsillitis is the 3rd most common infection that requires patients to see an otorhinolaryngologist. When episodes of tonsillitis recur, acute tonsillitis diagnosis turns into recurrent tonsillitis (RT). Exacerbations of RT are treated with antibiotics. Currently, the frequency of exacerbations in the last 3 years is used as the main determining factor in the selection of patients for elective tonsillectomy. If there are 7 episodes of tonsillitis in a year, or 5 episodes of tonsillitis in a year for 2 consecutive years, or 3 episodes of tonsillitis in a year for 3 consecutive years, tonsillectomy is recommended. The etiopathogenesis of RT is not clear and is being actively studied. The reason for ineffective antibacterial therapy is explained by specific resistance mechanisms of bacteria, formation of biofilms, insufficient concentration of antibiotics in tonsillar tissue. RT reduces patients` quality of life and is a medical and a financial burden. During exacerbation of RT a peritonsillar abscess (PTA) as a complication may develop. Therefore, the aim of the study was to identify the etiological agents of RT and PTA in tonsil crypts and parenchyma samples, to determine antibacterial resistance and biofilm formation capacity of pathogenic bacteria, and to evaluate their importance in the pathogenesis and clinical course of RT and PTA. The study included several parts: 1st part was dedicated for evaluating RT and PTA patients undergoing tonsillectomy. The RT group consisted of 99 patients who underwent planned tonsillectomy due to RT despite appropriate antibacterial therapy. The PTA patient group consisted of 29 patients who underwent acute tonsillectomy for drainage of peritonsillar abscess. The objective of 2nd part was to evaluate the most accurate method of obtaining samples from tonsillar crypts. The study group of 25 patients with RT was created. In this part, tonsillar crypt samples were obtained in 2 ways and the results were compared. The objective of 3rd part was to evaluate the microbiological results of tonsillar crypt sample of healthy individuals. A group of healthy individuals without tonsillar pathology consisted of 91 participants – students of Medical Faculty of Rīga Stradiņš University. In 4th part a bacteriological evaluation of post-tonsillectomy patients was performed. The group consisted of 16 patients who previously had RT and had a tonsillectomy performed a year ago. These patients were subjected to clinical and bacteriological evaluation. During each part tonsillar crypt samples were taken for bacteriological analysis, antibacterial sensitivity and biofilm production capacity of isolated strains was assessed. The examinations were carried out in the laboratory of the Biology and Microbiology Department of Rīga Stradiņš University and the Laboratory of Bacteriology of the Pauls Stradiņš Clinical University Hospital. During the study a biopsy needle was developed and patented for obtaining an optimal sample of tonsillar crypts. The study found that RT patients, compared to PTA patients and healthy individuals, had a higher diversity of microorganisms in the tonsillar crypts, the predominant pathogen being S. aureus. Biofilm forming strains were detected in RT, PTA patients, but no significant antibacterial resistance was detected and no relationship between the biofilm producing phenotype and antibacterial sensitivity was observed. Clinically relevant pathogens (S. aureus, K. pneumoniae, P. aeruginosa) and susceptible biofilm producing strains were isolated from tonsillar crypts of healthy individuals without tonsillar pathology. The tonsillar crypts of healthy individuals are an important reservoir of pathogenic bacteria and biofilm producing strains. The results of our study confirm that tonsillectomy is effective in preventing bacterial colonization. The thesis is presented as a unifying material of peer-review publications, it summarizes the results of the research. The obtained results on RT and oral microbiota are of international importance and contain recommendations for use in clinical practice. 3.2 Clinical Medicine; Sub-Sector – Otorhinolaryngology. Keywords: recurrent tonsillitis, peritonsillar abscess, biofilms, antibacterial susceptibility.

Background and Objective: Tonsillar crypts can be considered a reservoir for a variety of bacterial species. Some bacterial species can be considered part of the normal oropharyngeal microbiota. The roles of other pathogens, for example, the so-called non-oral and respiratory pathogens Staphylococcus aureus, Klebsiella, Pseudomonas, and Acinetobacter spp., which have strong virulence factors, biofilm production capacity, and the ability to initiate infectious diseases, are unclear. The purpose of this study was to detect the presence of S. aureus, K. pneumoniae, P. aeruginosa, and Acinetobacter spp. within the tonsillar crypts of healthy individuals, and to analyze the pathogens’ biofilm production and antibacterial resistances. Results: Only common oropharyngeal microbiota were cultivated from 37 participant samples (40.7%). The most commonly isolated pathogenic bacterium was S. aureus, which was isolated in 41 (45%) participant samples. K. pneumoniae was isolated in seven (7.7%) samples, Acinetobacter spp. were isolated in five (5.5%) samples, and P. aeruginosa was isolated in two (2.2%) samples. Biofilm producers predominated among the pathogenic bacteria; 51 strains were biofilm producers, and among them, 31 strains were moderate or strong biofilm producers. The tested S. aureus, K. pneumoniae, P. aeruginosa, and Acinetobacter spp. strains were sensitive to commonly used antibiotics (amoxicillin–clavulanic acid, clindamycin, or ciprofloxacin). One of the isolated S. aureus strains was MRSA. Conclusions: Biofilm is a commonly observed feature that seems to be a naturally existing form of pathogenic bacteria colonizing human tissue. S. aureus, K. pneumoniae, P. aeruginosa, and Acinetobacter spp. occasionally occur in the tonsillar crypts of healthy individuals, and, therefore, it is most likely that S. aureus, K. pneumoniae, P. aeruginosa, and Acinetobacter spp. in opportunistic tonsillar infections originate from the tonsillar crypt microbiota.

Background: Despite the widespread use of antibiotics to treat infected tonsils, episodes of tonsillitis tend to recur and turn into recurrent tonsillitis (RT) or are complicated by peritonsillar abscesses (PTAs). The treatment of RT and PTAs remains surgical, and tonsillectomies are still relevant. Materials and methods: In a prospective, controlled study, we analyzed the bacteria of the tonsillar crypts of 99 patients with RT and 29 patients with a PTA. We performed the biofilm formation and antibacterial susceptibility testing of strains isolated from study patients. We compared the results obtained between patient groups with the aim to identify any differences that may contribute to ongoing symptoms of RT or that may play a role in developing PTAs. Results: The greatest diversity of microorganisms was found in patients with RT. Gram-positive bacteria were predominant in both groups. Candida species were predominant in patients with a PTA (48.3% of cases). Irrespective of patient group, the most commonly isolated pathogenic bacterium was S. aureus (in 33.3% of RT cases and in 24.14% of PTA cases). The most prevalent Gram-negative bacterium was K. pneumoniae (in 10.1% of RT cases and in 13.4% of PTA cases). At least one biofilm-producing strain was found in 37.4% of RT cases and in 27.6% of PTA cases. Moderate or strong biofilm producers were detected in 16 out of 37 cases of RT and in 2 out of 8 PTA cases. There was a statistically significant association found between the presence of Gram-positive bacteria and a biofilm-formation phenotype in the RT group and PTA group (Pearson χ² test, p < 0.001). S. aureus and K. pneumoniae strains were sensitive to commonly used antibiotics. One S. aureus isolate was identified as MRSA. Conclusions: S. aureus is the most common pathogen isolated from patients with RT, and Candida spp. are the most common pathogens isolated from patients with a PTA. S. aureus isolates are susceptible to most antibiotics. Patients with RT more commonly have biofilm-producing strains, but patients with a PTA more commonly have biofilm non-producer strains. K. pneumoniae does not play a major role in biofilm production.

Background and objectives: Staphylococcus aureus (S. aureus) is often recovered from the pharynx. However, the role of this pathogen in the etiology of tonsillar inflammation is still unclear and complicated due to frequent carriage of S. aureus. The aim of the study was to evaluate the frequency and the clinical importance of S. aureus colonization and biofilm production ability in patients with recurrent tonsillitis (RT) using patient samples from tonsillar crypts during tonsillectomy, and from the throat, nasal cavity, and armpits after tonsillectomy. Materials and Methods: A case series study was carried out at a tertiary referral center among 16 patients diagnosed with RT who were undergoing tonsillectomy. Samples from tonsillar crypts were obtained during tonsillectomy, and samples from the throat, nasal cavity, and armpit were obtained a year after surgery. An evaluation of S. aureus incidence, biofilm formation, and antibacterial susceptibility was performed. Results: During tonsillectomy, 16 strains of S. aureus were isolated from 16 patients, while 15/16 S. aureus strains were biofilm producers. A year after tonsillectomy, 8 S. aureus strains were isolated from 6 out of 16 patients, while 6/8 S. aureus strains were biofilm producers. After tonsillectomy, 3 patients showed S. aureus in throat culture. Conclusions: In 10/16 cases S. aureus was the causative agent of RT, in 4/16 cases patients had a predisposition to colonization of S. aureus, and in 2/16 cases S. aureus was a part of the patients` oral microbiome. Tonsillectomy results in less frequent isolation of S. aureus strains.

Background and Objectives: Recurrent tonsillitis is an infection of the palatine tonsils. Samples for microbiological testing are usually obtained from the inflamed surface of the tonsils. Colonizing the surface bacteria does not always correlate with pathogens causing recurrent tonsillitis and there is no consensus or this in research studies. The aim of the study was to compare whether Staphylococcus aureus (S. aureus) and Klebsiella pneumoniae (K. pneumoniae) differ when isolated from the tonsillar surface or tonsillar crypts in patients with recurrent tonsillitis. Materials and Methods: a case series study was conducted at a tertiary referral center among 25 patients diagnosed with recurrent tonsillitis. An evaluation of S. aureus and K. pneumoniae incidence, biofilm formation and antibacterial susceptibility was performed. Results: There was a statistically significant association between surface and punch biopsy samples for S. aureus (Fisher’s Exact test p = 0.004) and K. pneumoniae (Fisher’s Exact test p < 0.001). A McNemar test did not reveal a statistically significant association. Although the antibacterial resistance profile was not broad, five out of nine S. aureus isolates were biofilm producers and four out of five K. pneumoniae isolates were biofilm producers. Conclusions: Surface and core cultures of tonsils are comparable with a differing incidence between the surface and the punch biopsy cultures for S. aureus and K. pneumoniae. A larger quantity of bacteria exist in surface samples suggesting that a biopsy sample may be less challenging in evaluating recurrent tonsillitis. We recommend that antibacterial susceptibility results are considered alongside the biofilm-forming potential of isolated bacteria.