Vol 30, No 2 (2025)

Background: Human herpesvirus 6 is a widespread pathogen, well known as the causative agent of exanthema subitum in children. However, data on the frequency of human herpesvirus 6 detection in cerebrospinal fluid and its role in the development of meningoencephalitis in immunocompetent children remain limited.

Aim: To assess the frequency of referral for cerebrospinal fluid testing for human herpesvirus 6 DNA using qualitative polymerase chain reaction, and to determine the seasonal patterns and the diagnostic significance of human herpesvirus 6 DNA detection in cerebrospinal fluid of immunocompetent children with suspected meningoencephalitis. Additionally, to analyze the frequency, seasonality, and clinical course of human herpesvirus 6 meningoencephalitis in immunocompetent children.

Methods: We conducted a descriptive retrospective study that included immunocompetent children with suspected meningoencephalitis admitted to Filatov Children’s City Clinical Hospital No. 5 between 2007 and 2018. All patients were examined by a pediatric infectious disease specialist and a neurologist. Routine laboratory tests and lumbar puncture with subsequent cerebrospinal fluid analysis were performed. Qualitative polymerase chain reaction was used to detect human herpesvirus 6 DNA in cerebrospinal fluid. The analysis included the frequency of referral for cerebrospinal fluid testing for human herpesvirus 6, the frequency of human herpesvirus 6 DNA detection in cerebrospinal fluid, and the clinical diagnoses of patients with human herpesvirus 6 detected in cerebrospinal fluid.

Results: Over a 12-year period, 712 patients with suspected meningoencephalitis underwent cerebrospinal fluid testing for human herpesvirus 6. Human herpesvirus 6 DNA was detected in 2.9% of cases. Analysis of 15 medical records of children with detected human herpesvirus 6 showed that 7 patients had no pathological cerebrospinal fluid changes but presented with typical clinical manifestations of exanthema subitum or fever without rash. Among 8 patients with pathological cerebrospinal fluid changes, 2 cases of human herpesvirus 6 meningoencephalitis were confirmed. Thus, human herpesvirus 6 DNA detection in cerebrospinal fluid of immunocompetent children is rare and in most cases (86%) does not indicate human herpesvirus 6–induced meningoencephalitis.

Conclusion: Over 12 years, among 712 patients at Filatov Children’s City Clinical Hospital No. 5 with suspected meningitis and/or encephalitis, human herpesvirus 6 meningoencephalitis was confirmed in only 2 infants (0.3%). Human herpesvirus 6 DNA may be present in normal cerebrospinal fluid during primary herpesvirus infection. This should be considered when establishing a diagnosis and deciding on the initiation of antiviral therapy.

Background: Environmental surveillance across Russian regions has documented the consistent isolation of nontoxigenic Vibrio cholerae strains and the sporadic detection of individual toxigenic Vibrio cholerae О1 El Tor strains. Heavy metals in the environment are considered among the factors that may drive the evolution of V. cholerae. Assessment of the tolerance of nontoxigenic V. cholerae О1 strains from water sources confirmed the presence of isolates resistant to a wide range of heavy metals in various combinations. Few investigations have addressed the genetic basis of heavy metal tolerance in Vibrio species, and no data are available on heavy metal resistance genes in toxigenic V. cholerae.

Aim: The work aimed to identify potential genes conferring heavy metal resistance in toxigenic V. cholerae.

Methods: Two V. cholerae O1 strains—83 and 5879—and Escherichia coli QD5003 Rif ^r were used. For in silico analysis, 1880 complete genomes of toxigenic V. cholerae belonging to different serogroups and collected over different periods were screened.

Results: Comparative bioinformatic analysis using genome subtraction identified the czcA gene (NCBI GenBank accession number MVB73536.1) in V. cholerae strain 83. Analysis of the sequenced genomes of 1880 V. cholerae strains from various serogroups and collection periods detected the czcA gene in 159 of 1125 toxigenic strains (14.1%), but in none of the 775 nontoxigenic genomes. The presence of the czcA gene in V. cholerae strain 83 as part of an integrative and conjugative element of the ICEVchBan11 type was confirmed by in silico polymerase chain reaction (PCR) using virtual primers. Among the 159 czcA-positive genomes of V. cholerae, two integrative and conjugative element types were reliably identified: 113 ICEVchBan9 and 27 ICEVchBan11. To investigate the possible biological role of czcA, the ICEVchBan11 was transferred by conjugation into V. cholerae 5879 cells. The resulting czcA-positive 5879 strain cells showed a significant increase in resistance to cadmium ions.

Conclusion: These findings suggest that the presence of the czcA gene in toxigenic V. cholerae may enhance resistance to the toxic effects of heavy metals. In particular, this may provide the bacteria with a selective advantage in aquatic environments with elevated cadmium ion concentrations.

Prevention of nosocomial infections in cardiac surgery patients during the postoperative period is a critical task, both from an economic perspective and for improving the quality and longevity of life in patients with cardiovascular diseases. The relevance of assessing the risk of infectious complications in this population is confirmed by numerous publications in both Russian and international journals. An analysis of original studies and reviews in Embase, PubMed, ResearchGate, eLibrary, and Google Scholar indicated that effective prediction of nosocomial infections in cardiac surgery patients requires consideration of a combination of parameters that exert a synergistic influence on infection risk. Key preoperative risk factors include age over 60 years, body mass index >24 kg/m², smoking, hypertension, diabetes mellitus, chronic obstructive pulmonary disease, severe chronic heart failure, peripheral vascular disease, and previous cardiac surgery. Upon hospital admission, the likelihood of developing nosocomial infections may be influenced by pronounced preoperative hypoalbuminemia, anemia, low hematocrit, and elevated serum creatinine. Intraoperative risk factors include cardiopulmonary bypass duration exceeding 120 minutes, intraoperative blood loss > 2000 mL, and infusion of large volumes of replacement fluids. In the future, artificial intelligence could be utilized to develop a risk assessment scoring system.

The role of the pathobiome and chronic infectious foci in the development of nosocomial complications in cardiac surgery patients remains insufficiently studied and requires further research. Endogenous sources of infection may play a more significant role in the development of nosocomial infections than exogenous contamination.

Due to its wide spectrum of clinical manifestations and severe course associated with high mortality, meningococcal infection remains a socially significant disease.

Currently, an increase in cases of meningococcal infection with atypical clinical manifestations is being observed, which are characterized by higher mortality rates. This is associated both with microbiological features of the pathogen and with diagnostic and therapeutic errors in managing such patients. Early microbiological testing serves as a key diagnostic method for atypical forms of the disease. In the absence or late initiation of treatment, the generalized form of meningococcal infection almost invariably leads to death. Even with timely and adequate therapy, mortality reaches 10%–15%, and up to 20% of survivors suffer from disabling sequelae that significantly reduce quality of life.

This article describes a clinical case of a generalized form of meningococcal infection in an otherwise healthy 43-year-old man. The infection was caused by a nontypeable Neisseria meningitidis, and the disease manifested as fulminant sepsis with shock, gastroenteritis, and pronounced abdominal syndrome without hemorrhagic rash or meningeal signs. Meningitis was confirmed only by histopathological examination of brain tissue. Despite intensive therapy, the infection progressed rapidly, resulting in death 18 hours after the onset of initial symptoms.

This case demonstrates that the generalized form of meningococcal infection may present with sepsis and gastrointestinal symptoms in the absence of hemorrhagic rash and meningeal signs. Physicians in both outpatient and hospital settings should consider this possibility in their diagnostic evaluation.