The coast of the Bulgarian Black Sea is a popular summer holiday destination. The Dam of Iskar is the largest artificial dam in Bulgaria, with a capacity of 675 million m3. It is the main source of tap water for the capital Sofia and for irrigating the surrounding valley. There is a close relationship between the quality of aquatic ecosystems and human health as many infections are waterborne. Rapid molecular methods for the analysis of highly pathogenic bacteria have been developed for monitoring quality. Mycobacterial species can be isolated from waste, surface, recreational, ground and tap waters and human pathogenicity of nontuberculose mycobacteria (NTM) is well recognized. The objective of our study was to perform molecular analysis for key-pathogens, with a focus on mycobacteria, in water samples collected from the Black Sea and the Dam of Iskar. In a two year period, 38 water samples were collected—24 from the Dam of Iskar and 14 from the Black Sea coastal zone. Fifty liter water samples were concentrated by ultrafiltration. Molecular analysis for 15 pathogens, including all species of genus Mycobacterium was performed. Our results showed presence of Vibrio spp. in the Black Sea. Rotavirus A was also identified in four samples from the Dam of Iskar. Toxigenic Escherichia coli was present in both locations, based on markers for stx1 and stx2 genes. No detectable amounts of Cryptosporidium were detected in either location using immunomagnetic separation and fluorescence microscopy. Furthermore, mass spectrometry analyses did not detect key cyanobacterial toxins. On the basis of the results obtained we can conclude that for the period 2012–2014 no Mycobacterium species were present in the water samples. During the study period no cases of waterborne infections were reported.

Streptococcus pneumoniae colonises the mucosal lining of the upper respiratory tract and is an important cause of invasive infections affecting young children, adults over 65 years of age, the immunocompromised and individuals with chronic diseases. Recent studies have shown variations in virulence based on the high rate of pneumococcal recombination. PCR-based molecular methods are highly sensitive, specific and are becoming the preferred tool for quick and accurate diagnosis of bacterial meningitis which is required to be defined within 2-3 hours. During the 5-year survey period (2013-2017), 202 materials received as cerebrospinal fluid samples and pneumococcal strains isolated from patients diagnosed with meningitis, were examined by Real-time PCR in the reference laboratory at NCIPD. Serotyping of S. pneumoniae-positive materials was performed with conventional multiplex PCR and Real-time PCR with primers for 41serotypes/serogroups. There is a high incidence of S. pneumoniae serotypes not covered by the pneumococcal conjugate vaccine (PCV10) currently used in Bulgaria. It was found that all cases of meningitis caused by S. pneumoniae vaccine serotypes occurred in patients that were not vaccinated.

The transmission of water-borne pathogens typically occurs by a faecal-oral route, through inhalation of aerosols, or by direct or indirect contact with contaminated water. Previous molecular-based studies have identified viral particles of zoonotic and human nature in surface waters. Contaminated water can lead to human health issues, and the development of rapid methods for the detection of pathogenic microorganisms is a valuable tool for the prevention of their spread. The aims of this work were to determine the presence and identity of representative human pathogenic enteric viruses in water samples from six European countries by quantitative polymerase chain reaction (q-PCR) and to develop two quantitative PCR methods for Adenovirus 41 and Mammalian Orthoreoviruses. A 2-year survey showed that Norovirus, Mammalian Orthoreovirus and Adenoviruses were the most frequently identified enteric viruses in the sampled surface waters. Although it was not possible to establish viability and infectivity of the viruses considered, the detectable presence of pathogenic viruses may represent a potential risk for human health. The methodology developed may aid in rapid detection of these pathogens for monitoring quality of surface waters.

Background: N. gonorrhoeae and M. genitalium infections remain public health concern due to emerging antimicrobial resistance which compromise effective treatment and infection prevention and control. Objective: To estimate the prevalence for N. gonorrhoeae and M. genitalium infections and identify demographic and sexual behavioral risk factors in Bulgarian population of reproductive age from Sofia municipality. Material and methods: Participants were sexually active 443 men and 198 women aged 18-49 years. They answered questionnaires on sexual behavior and provided samples for N. gonorrhoeae and M. genitalium testing. Results: The prevalence of N. gonorrhoeae infection was 3.28% (21/641) and with M. genitalium infection it was 2.49% (16/641). For both infections the presence of urogenital symptoms was associated with greater risk of being infected. Among gonococcal infections an increased number of lifetime partners and partners during the last 6 months, previously diagnosed STIs and use of contraception other than condoms were associated risk factors. Conclusions: The prevalence of N. gonorrhoeae and M. genitalium infections in Bulgarian population of reproductive age from Sofia municipality was relatively low but due to significant disease burden data on prevalence and identified risk factors should help the development of future control strategies.

Introduction: Mycoplasma genitalium is an established cause of sexually transmitted infections in men and women. Current guidelines recommend azithromycin and moxifloxacin as first- and second-line treatment, respectively. However, azithromycin treatment failure has been increasingly reported. The aim of this study was to determine the efficacy of azithromycin and alternative antibiotic regimens in a prospective cohort of M. genitalium-positive patients, and macrolide resistance mutations associated with azithromycin failure. Materials and methods: Consecutive eligible M. genitalium-positive patients attending the National Center of Infectious and Parasitic Diseases in Sofia, Bulgaria between 1 January 2018 and 31 December 2020 were treated with azithromycin and retested by polymerase chain reaction 21-28 days after completion of the treatment. Cure was defined as M. genitalium-negative result on the test of cure. Cases failing azithromycin were treated with moxifloxacin and retested another 21-28 days after treatment. Pre- and post-treatment samples were assessed for macrolide resistance mutations by conventional DNA sequencing. Results: Of 21 patients treated with azithromycin, 11 (52.4%) were cured. Pre- and post-treatment macrolide resistance mutations were detected in 10 (47.6%) patients, and all of them failed azithromycin. Moxifloxacin was effective in all cases failing azithromycin; and all were M. genitalium-negative at the test of cure after moxifloxacin treatment. Conclusions: In this study a high azithromycin failure rate (47.6%) in an M. genitalium-positive cohort in association with high levels of pretreatment macrolide resistance was reported. Moxifloxacin was highly effective in treating macrolide-resistant infections. These findings necessitate implementation of new diagnostic and therapeutic strategies such as sequential antimicrobial therapy for M. genitalium guided by a macrolide-resistance assay.