Eravacycline is a third-generation tetracycline, a fluorocycline agent with two modifications that distinguish it from tigecycline. Eravacycline demonstrated effectiveness against various gram-positive and gram-negative facultatively anaerobic bacteria, including multidrug resistant Enterobacterales, Acinetobacter baumannii, staphylococci, enterococci, and pneumococci. However, whereas numerous studies focused on the impact of eravacycline on facultative anaerobic microbes, there is limited data regarding its efficacy against anaerobes. The aim of the present review was to compare eravacycline activity to that of other antibiotics used against anaerobic/microaerophilic bacteria and to assess potential benefits of the newer agent in anaerobic or mixed aerobic-anaerobic infections. We encompassed information from the literature published in English and included our own pilot study. Compared to most comparator antibiotics, eravacycline was more effective against anaerobes, including Bacteroides/Parabacteroides, Prevotella, Fusobacterium, Clostridioides difficile and other clostridial species, as well as gram-positive anaerobic cocci, and Cutibacterium acnes. Most frequently, eravacycline MICs were ≥4 to ≥8-fold lower than those of most comparator antibiotics. In addition, eravacycline did not trigger an infection with C. difficile and is considered a tolerable medication. So far, only the injectable eravacycline administration for complicated intraabdominal infections has been approved. However, more studies in more countries are needed to assess its usefulness for combination treatment and still not labeled indications.

INTRODUCTION:There is limited information on the prevalence of Helicobacter pylori seropositivity in pediatric patients with type 1 diabetes mellitus (T1DM), despite the fact that both conditions constitute significant healthcare issues. However, in these children, H. pylori seropositivity may worsen both glycemic control and diabetes management. MATERIALS AND METHODS:This study sought to determine the prevalence of CagA IgG and H. pylori IgG antibodies in Bulgarian children with T1DM. RESULTS:Of the 334 children assessed, 20.4% were H. pylori seropositive and 15.0% were CagA seropositive. Fewer children aged 1 to 6 years tested positive for H. pylori (12.2%) and CagA (8.7%) than those aged 7 to 17 years (24.7% and 18.3%, respectively). Among the 145 diabetic children, 28.3% were H. pylori positive versus only 14.3% of the 189 control participants. In addition, significantly more (23.4%) diabetic children were CagA positive, compared to 8.5% among the controls. CONCLUSION:H. pylori seropositivity was twice as common in children with T1DM compared to the control group. Likewise, pediatric patients were approximately three times more frequently seropositive for more virulent strains (CagA-positive status) than other children. If confirmed as an active infection, early diagnosis of H. pylori- and CagA-seropositive children may lower the lifetime risk of gastric cancer and peptic ulcers in adulthood. The current study's findings support additional prospective research before screening recommendations are issued.

Helicobacter pylori is a species with a highly plastic genome encoding numerous virulence factors, such as the pathogenicity island (cagPAI) and vacuolating cytotoxin A (VacA). cagPAI consists of more than 26 genes, with cagA and especially cagE being essential predictors of cagPAI intactness. vacA gene has numerous allelic variations, among which s1m1i1 is the most virulent. The aim of our study was to assess cagA/cagE gene frequency and } allele status among clinical H. pylori isolates from Bulgaria for the period 2017–2024 and to compare the data with that from our previous study (2004–2010). In the current study, the rates of cagA, cagE, and the combination cagA(+)/cagE(+) were significantly lower compared to the previous study, as were the rates of the combinations vacA s1m1i1 and cagA+/cagE+/s1m1i1. In conclusion, H. pylori evolution showed a statistically significant decrease in the prevalence of cagA+/cagE+/vacA s1m1i1 virulence genotype over 14 years, observed in the groups of total patients, as well as in the subgroups of adults and non-ulcer patients.

The influenza vaccine provides effective protection against seasonal flu, helping to reduce the risk of infection, severe illness, and complications. This study analysed attitudes, awareness, and practices related to the seasonal influenza vaccine among students at the Medical College "Yordanka Filaretova" in Sofia. A voluntary and anonymous survey was conducted with 97 students from the Medical Laboratory Technician programme and 54 from the Public Health Inspector programme, resulting in 84 completed responses. More than half of the respondents (62.0%) believe that young, healthy individuals do not need the vaccine, while 63.1% expressed concerns about potential side effects. A total of 11.9% respondents consider the vaccine ineffective, and 34.5% could not form an opinion on its effectiveness; 26.2% indicated they would get vaccinated if it were free, and 28.6% reported a lack of information about the vaccine. Increased awareness of the importance of the influenza vaccine and its benefits is crucial for benefit/risk assessment.

The present study aimed to explore the genomic characteristics of an extremely rare clinical Weissella viridescens isolate (designated Wvir453), obtained in 2022 from the blood sample of a Bulgarian 37-year-old critically ill male patient diagnosed with spinal meningeal melanocytoma. Species identification using MALDI-TOF mass spectrometry, antimicrobial susceptibility testing, whole-genome sequencing, pangenomic, phylogenomic, and virulome analyses were performed. The isolate demonstrated high-level intrinsic resistance to glycopeptides, probable resistance to penicillin G and trimethoprim-sulfamethoxazole, and susceptibility to ampicillin, imipenem, clindamycin, tetracycline, ciprofloxacin, and linezolid. The observed genome size (1.73 Mb) and GC content (40.73

Featured Application Our study demonstrates the importance of integrating PCR with classical culture methods for accurate microbiological assessment in pediatric caries research.Abstract Accurate identification of cariogenic bacteria is crucial for understanding caries development in children. Classical culture methods often underestimate microbial diversity, while polymerase chain reaction (PCR) can detect species that are difficult to cultivate. The aim of this study was to compare culture-based and PCR-based methods for detecting key cariogenic microorganisms in the carious dentin of pediatric patients. Thirty dentin samples were collected from the permanent teeth of children aged 8-14 years. Parallel analyses were performed using standard culture techniques and PCR targeting the gtfB gene of S. mutans and the 16S rRNA gene of Lactobacillus spp. Culture results were quantified as colony-forming units, while PCR results were classified as negative, low-positive, or positive. The results show that culture-based methods identified S. mutans in 16.7% of the samples and Lactobacillus spp. in 3.3%, while PCR identified a signal for S. mutans in 43.3% and Lactobacillus spp. in 100% of the samples. PCR-based methods provide higher sensitivity for detecting key cariogenic bacteria, including S. mutans and Lactobacillus spp. However, PCR detects bacterial DNA and does not indicate bacterial viability or activity. Combining molecular and culture-based approaches allows a more comprehensive assessment of the cariogenic microbiota, supporting accurate microbiological evaluation in pediatric caries research.

Background: Pyoderma is a common dermatological condition in dogs caused by various bacteria that are typically part of the normal microbiota. Staphylococcus pseudintermedius and Proteus mirabilis are opportunistic pathogens frequently encountered in canines, producing multiple virulence factors with the potential to cause life-threatening infections. Case Description: We report the case of a 5-year-old dog presented with skin lesions that generalized to a life-threatening condition. The initial treatment with corticosteroids, anti-parasitic medications, and antibiotics was ineffective. Proteus mirabilis was isolated as a sole agent and treated according to the antibiogram with no effect. In subsequent microbiological testing, methicillin-resistant and multidrug-resistant S. pseudintermedius was identified as a coagent using mass spectrometry. The dog died a little over two months after the first symptoms, with clinical signs of septic shock. This case demonstrates the severe complications caused by canine pyoderma and the challenges in the diagnosis and treatment of a mixed enterobacterial/staphylococcal infection. Furthermore, it highlights the significance of evaluating antibiotic susceptibility and the necessity for repeated microbiological sampling when the patient's condition worsens, despite the results presented. Conclusion: The empirical administration of corticosteroids and beta-lactams is inappropriate in skin lesions with unclear etiology because corticosteroids may enhance the progression of the infection, whereas beta-lactams are inactive in canine staphylococci in most cases.

It is crucial to consider newer antibiotics with activity against anaerobes and Helicobacter pylori, given their healthcare importance, and the constantly growing antibiotic resistance/multidrug resistance, which complicates the therapy. The aim of this review was to emphasize certain recently approved or still-under-investigation antibiotics with potential benefits for treating Clostridioides difficile infections (CDIs), other anaerobic infections, and those caused by H. pylori, covering recent data from articles published primarily in 2020-2026. Given the limited number of antibiotics for treating CDI and fidaxomicin nonavailability in many countries, it is necessary to conduct more extensive laboratory and clinical studies of promising antibiotics such as ibezapolstat, delafloxacin, lascufloxacin, omadacycline, eravacycline, ridinilazole, and CRS3123. Against Bacteroides fragilis group species, delafloxacin and eravacycline showed good activity. Research on rifasutenizol for bacterial vaginosis, sarecycline and nadifloxacin for acne vulgaris and amixicile for periodontal diseases needs to be expanded. For H. pylori infection, delafloxacin, sitafloxacin, nemonoxacin, zoliflodacin, and rifasutenizol may improve the suboptimal success of most eradication regimens. However, more efforts, in coordination between medical, scientific, manufacturing, and government representatives, should ensure wider access to and research on the newer antibacterials. Establishing more research groups, careful examination of market issues, and additional approaches, such as nanomaterials, efflux pump inhibitors, phage therapy, and CRISPR-Cas systems, should be beneficial. Notwithstanding the difficulties, there are many opportunities to promote research on and potential use of newer antibiotics which show advantages over the older antibacterials, and to make them available to numerous countries and patients worldwide.

Background: Antibiotic resistance in Helicobacter pylori is steadily increasing, rendering the treatment of related gastroduodenal diseases increasingly difficult. Lefamulin is a new broad-spectrum antibacterial in the pleuromutilin class, acting by suppressing bacterial protein synthesis. It has the advantages of its unique “induced-fit” mechanism, a low frequency of spontaneous mutations, stepwise development of resistance, stability in acidic environments, and potential for additive or synergistic activity when combined with certain other antibiotics against various facultative anaerobes, including multidrug-resistant isolates. Methods: We investigated, for the first time to the best of our knowledge, the activity of lefamulin against 91 clinical H. pylori isolates from symptomatic adult patients using MIC test strips. Results: Overall, lefamulin MICs50 and MICs90 were 0.25 and 2 mg/L versus 4 and ≥256 mg/L for clarithromycin, and 0.75 and ≥32 mg/L, respectively, for levofloxacin. Lefamulin MICs50 and MICs90 were 0.5 mg/L and 4 mg/L against the 61 clarithromycin-resistant (MICs, >0.25 mg/L) isolates, 0.25 and 0.75 mg/L against the 40 levofloxacin-resistant (MICs, >1 mg/L) isolates, and 0.38 mg/L and 0.75 mg/L, respectively, against the 28 isolates resistant to both agents. Conclusions: Briefly, the new pleuromutilin antibiotic outperformed in vitro both clarithromycin and levofloxacin against H. pylori isolates. Its potential usefulness in treating H. pylori infections resistant to macrolides and fluoroquinolones, and especially those with dual resistance, justifies further investigation. However, some precautions should also be considered. The use of the novel antibiotic lefamulin may offer benefits for H. pylori eradication if our results are confirmed in subsequent studies, including clinical trials.

Background/Objectives: In the context of minimally invasive dentistry, photodynamic therapy (PDT) is regarded as a biologically oriented method for controlling microbial activity during caries excavation. Brix 3000 is a modern material used in chemo-mechanical removal of carious lesions, enabling selective elimination of infected dentin. The present study compares the antimicrobial effectiveness of Brix 3000 and adjunctive PDT performed with the FotoSan 630 Intro Kit. Methods: This study included 30 children aged 4-7 years with carious lesions on primary molars classified as ICDAS II code 06. The lesions were allocated into two groups: Group 1 (the control group), encompassing 15 lesions excavated using Brix 3000 only, and Group 2 (the experimental group), encompassing 15 lesions excavated with Brix 3000 followed by adjunctive PDT with the FotoSan 630 Intro Kit. A total of 75 microbiological samples were collected: 30 from infected dentin before excavation, 30 from partially infected dentin after Brix 3000, and 15 (experimental group only) after subsequent PDT. Results: The results revealed a wide diversity of cariogenic microorganisms in the infected dentin, with S. mutans being the most frequently isolated and present in the highest quantities. Using Brix 3000 reduced microbial diversity and quantity following excavation of partially infected dentin, although S. mutans persisted at lower levels. Conclusions: After the additional photodynamic disinfection, no microorganisms were isolated from the partially infected dentin. Adjunctive PDT provides localized, non-invasive antimicrobial disinfection and can be integrated into minimally invasive caries management in primary teeth.

Facial paralysis is an infrequent and serious potential complication of acute otitis media (AOM). We describe a pediatric case of rapidly progressive facial paralysis as a secondary complication alongside AOM, caused by the non-typeable Haemophilus influenzae (NTHi) strain, which was managed with facial nerve decompression, glucocorticoid medication, and antimicrobial chemotherapy. The reasons why NTHi becomes pathogenic in certain patients are not yet fully understood, and the specific interactions and adaptations that lead to complications must be further investigated, as they result in more complex treatment approaches.

Coculture systems (CCSs) are experimental tools used to study the interactions of anaerobic bacteria among themselves and the gut epithelial cells under conditions simulating the human gut, unlike those in animal models. Although the studies on animal models are useful in determining the relationship between the causative agents of infections and human infections, they have disadvantages, such as ethical issues, in addition to the differences in the microbiota of the animal and humans. Therefore, the results obtained using animal models cannot be directly extrapolated to humans. CCSs can more completely reflect in vivo gut homeostasis and contribute to better understanding of the interplay between the intestinal cells and anaerobes, prevalent among the gut bacteria. Moreover, they provide new insights on the pathogenesis of infections and aid in assessing the usefulness of new probiotics and antibacterials. Therefore, CCSs, including the gut-on-a-chip models, can significantly improve microbiota-based therapy. Moreover, they can also be used to detect microbiota-derived metabolites such as those with mutagenic properties. The aim of this review was to explore selected CCS models of anaerobes with intestinal epithelium and their application in investigating intestinal homeostasis. The focus was to highlight the application of different CCSs and important data obtained from their implementation.

Pregnancy is a special period characterized by changes in the immune system as well as alteration of the microbiota predisposing to opportunistic infections, including tonsillopharyngitis. Streptococcus anginosus has numerous virulence factors, and it is associated with a variety of diseases. Being a part of the normal oral microbiota, it can be overlooked as a causative agent of infections in the oral cavity. A clinical case of a 29-year-old pregnant female who was allergic to penicillins and presented with recurrent tonsillopharyngitis has been described. Previous microbiological examinations have not shown any etiologic cause of patient’s symptoms. Two species were isolated. S. anginosus and S. oralis were identified using various methods, including nucleotide sequencing. S. anginosus was defined as the causative agent. Both were susceptible to all tested antibiotics. S. anginosus was positive for the duplicated sagA gene, encoding streptolysin S, an important factor of virulence. Based on clinical symptoms, paraclinical tests, immune competence, and characteristics of the strain, a multifactorial evaluation is required to determine whether an opportunist is a causative agent. Moreover, treatment of pregnant patients, particularly with antibiotics, is limited, which leads to therapeutic difficulties.

It is estimated that approximately 90% of all head and neck cancers are squamous cell carcinomas with a complex and multifactorial etiology. Molecular and epidemiological studies provide evidence for the role of oncogenic viruses in the initiation and/or oncomodulation of head and neck squamous cell carcinoma. Objectives: The present study aimed to detect the presence of high- and low-risk HPV, BKPyV, EBV, HCMV, HSVs in biopsy samples of squamous cell carcinoma of the external auricle in patients in Bulgaria. Materials and Methods: The study included 41 biopsy specimens from etiologically undiagnosed cases of squamous cell carcinoma of the external auricle. Molecular biological methods were used to detect the viruses—conventional and nested PCR, and sequence analysis. Results: The results obtained showed that none of the samples were found to have a high-risk HPV genotype. The highest percentage of samples showed genotype 6/11, and the lowest number of samples showed low-risk genotype 44. Of all herpesviruses, EBV was found in the largest proportion of samples, being present in the sample as a co-infection with HPV and always together with genotype 6/11. The frequency distribution, as a percentage and number of samples, of the possibilities for co-infection of EBV with each of the HPV genotypes was established. Of the remaining herpesviruses, the presence of HSV 2 was not confirmed in any of the samples. HSV 1 was present in only three of the samples, as a co-infection with genotypes 6/11, 42 and 43. When examining the samples for the presence of HCMV, only one positive sample was found, with both HPV 6/11 and 42 additionally present in the sample. Conclusions: For the first time, HPV, BKPyV, EBV, HCMV and HSVs were investigated and their possible involvement alone or as co-infection in the carcinogenesis of squamous cell carcinoma of the external auricle in patients in Bulgaria. The presence of the mentioned viruses, as well as the non-random distribution of EBV + HPV 6/11 and EBV + HPV 44, proven by us, does not necessarily make them etiological agents, but they could, through different and known mechanisms, influence the initiation and/or modulation of carcinogenesis.

The COVID-19 pandemic boosted antibiotic use in Bulgaria. The aim of the study was to evaluate for the first time in our country, the influence of the COVID-19 pandemic on both characteristic, prevalence and antibiotic susceptibility of Clostridioides difficile. We investigated 75 C. difficile strains isolated since the pandemic compared with 52 strains from 2013–2019. In 2020–2023, the toxigenic strains (TCDs) were 92.0% of all strains vs. 57.7% of those isolated beforehand. In 2020–2023, TCD resistance was metronidazole 5.8%, vancomycin 1.4%, and fidaxomicin 1.6%, without significant differences between the two periods. We observed a 5.5-fold increase in the prevalence of hypervirulent (HCD) strains. In HCD strains in 2020–2023, metronidazole resistance was 7.9%. Notably, resistance to levofloxacin 1 and 32 mg/l was 91.9% and 75.8%, respectively, in TCD strains from 2020–2023. Briefly, the increase in both TCD and HCD strains and the presence of resistance to all three antibiotics for treating C. difficile infections imply the need for susceptibility testing of all TCD isolates. The strikingly high levofloxacin resistance was linked to fluoroquinolone consumption in Bulgaria. The results stress the need for regular monitoring of antibiotic susceptibility of TCD strains, and strict adherence to the antibiotic policy.

Delafloxacin is one of the newest fluoroquinolones with a unique structure, determining better pharmacokinetic and pharmacodynamic properties, a better safety profile, and a broader spectrum of activity compared to older quinolones. We aimed to examine the susceptibility rates of delafloxacin, the genetic mechanisms contributing to resistance, and the serotype distribution in both invasive and non-invasive Streptococcus agalactiae strains. A total of 301 streptococcal strains were tested for minimal inhibitory concentration (MIC) to delafloxacin. All delafloxacin-resistant strains were subjected to serotyping, PCRs for quinolone-resistant genes, and sequence analysis for missense and silent mutations. Among the tested isolates, we found a 5.6% non-susceptibility rate to delafloxacin. The MICs ranged between 0.09 and 0.38 µg/mL, with a breakpoint for nonsusceptibility set as >0.03 µg/L, according to EUCAST criteria. All resistant isolates harboured missense mutations that led to amino acid substitutions in both GyrA (S81L) and ParC (S79F). Two common serotypes were determined among the resistant isolates: V (47.1%) and III (41.2%). Two strains were non-typable (11.7%). A statistical significance in the distribution of serotypes between delafloxacin-resistant and delafloxacin-susceptible strains was found. These findings highlight a concerning pattern of drug resistance developing prior to the introduction of a new medication, attributed to the extensive use of current antibiotics.

Delafloxacin is a potent 4th-generation fluoroquinolone with enhanced activity in acidic environments. However, recently, delafloxacin resistance in facultative anaerobic species has been reported. Thus, we examined levofloxacin and delafloxacin susceptibility of 98 Helicobacter pylori strains in 2020-2023. Minimum inhibitory concentrations (MICs) were detected with E tests. Levofloxacin resistance was 33.7%, while delafloxacin resistance was 2.0% at 1 mg/l (the levofloxacin resistance breakpoint for H. pylori), and 9.2% at 0.125 mg/l (the recently suggested delafloxacin ECOFF for the species). Overall proportion of the strains exhibiting >0.125 mg/l delafloxacin MICs was similar to that in the previous study in 2018-2019 (8.5%). None of the 65 levofloxacin susceptible strains had delafloxacin MICs of >0.125 mg/l. Among levofloxacin resistant strains, delafloxacin MICs >1 mg/l (6.1%, 2/33 strains) were detected only in 2022 and 2023. Briefly, the results showed the much higher activity of delafloxacin over levofloxacin. The high delafloxacin activity in acidic environments is an additional advantage of the newer fluoroquinolone for treating H. pylori infection. Given that fluoroquinolone-based eradication regimens can be used as a second- or third-line therapy for H. pylori, testing the susceptibility of levofloxacin-resistant strains to delafloxacin could provide a useful option for eradication of the frequent and potentially carcinogenic bacteria. New regimens, such as the combination of vonoprazan with delafloxacin and another antibiotic deserve investigation.

Cutibacterium acnes subspecies/phylotypes can cause infections requiring antibiotic therapy. Phylotyping of 73 (55 acneic and 18 non-acneic) C. acnes strains was performed, and antibiotic susceptibility was tested by E tests, breakpoint susceptibility test, or disk diffusion method. The dominant phylotype in both acneic and non-acneic strains was IA1 (56.2%). Phylotype II was >3-fold more frequent in non-acneic than acneic isolates. Resistance in acneic strains was >41% for clindamycin, 36.4% for tetracycline and 15.9% for levofloxacin, and that in non-acneic strains was >38% for clindamycin, 22.2% for tetracycline and 5.6% for levofloxacin. No strain was piperacillin/tazobactam or vancomycin resistant. Amoxicillin resistance was found in both acneic (5.4%) and non-acneic strains (11.1%), and was rare (1.8%) in phylotype I but higher (23.5%) in other strains. Double resistance was found in 32.6% of acneic and 22.2% of the non-acneic strains, and 9.3% of acneic strains displayed multidrug resistance. In conclusion, IA1 phylotype was dominant in both acneic and non-acneic strains, and type II was more frequent in non-acneic isolates. The detection (at >6%) of amoxicillin resistance represents a rare yet important finding. The presence of double/multidrug resistance strongly implies the need of susceptibility-guided therapy of the associated infections.

Lactococcosis caused by Lactococcus garvieae is a bacterial infection affecting fish with a considerable economic impact. Recently, L. garvieae has established itself as an opportunistic pathogen in humans. The aim of the current study was to test classical and molecular-biological methods for the identification of L. garvieae and examine antimicrobial susceptibility and capsule production, an important virulence factor. Additionally, tests for differentiation from closely related species, as well as epidemiological typing, were performed. In a period of 18 years (2002-2019), 24 isolates presumptively identified as L. garvieae were collected from Oncorhynchus mykiss and Salmo salar fish obtained either from retail stores or fish farms. In order to confirm the species, optimized PCR-based protocols were used. As a result, 21 of the tested strains were proved to be L. garvieae (n = 21). The remaining three isolates were Lactococcus lactis, Streptococcus iniae, and Enterococcus faecalis. Epidemiological typing by randomly amplified polymorphic DNA was performed. Except for a single KG+ isolate, all other strains belonged to the European capsular serotype KG-. All L. garvieae isolates showed susceptibility to all tested antibiotics with the exception of clindamycin, which was a diagnostic sign. A thorough optimization of diagnostic methods is essential to determining the etiology of specific infections affecting the personnel at risk in fish farms, the food industry, or within the broader community.