Resurrection of endogenous retroviruses during aging reinforces senescence.

Whether and how certain transposable elements with viral origins, such as endogenous retroviruses (ERVs) dormant in our genomes, can become awakened and contribute to the aging process is largely unknown. In human senescent cells, we found that HERVK (HML-2), the most recently integrated human ERVs, are unlocked to transcribe viral genes and produce retrovirus-like particles (RVLPs). These HERVK RVLPs constitute a transmissible message to elicit senescence phenotypes in young cells, which can be blocked by neutralizing antibodies. The activation of ERVs was also observed in organs of aged primates and mice as well as in human tissues and serum from the elderly. Their repression alleviates cellular senescence and tissue degeneration and, to some extent, organismal aging. These findings indicate that the resurrection of ERVs is a hallmark and driving force of cellular senescence and tissue aging.

A Case of Urinary Tract Infection Caused by Multidrug Resistant Streptococcus mitis/oralis.

S. mitis/oralis has been previously reported in isolated cases of bacterial endocarditis and liver abscesses. Its presence in urine is generally considered a contaminant. A 66-year-old male patient was admitted to the hospital due to recurrent chest tightness and four-year history of exertional dyspnea. On the second day of admission, the patient presented with urgent and frequent urination, as well as dysuria. Both initial and subsequent urine cultures showed S. mitis/oralis infection, with polymorphonuclear leukocyte phagocytosis observed in the second sample. MALDI-TOF results confirmed the isolated strain as S. mitis/oralis. Drug susceptibility testing revealed multidrug resistance to penicillin, ceftriaxone, cefepime, levofloxacin, ofloxacin, and tetracycline, but sensitivity to quinupristin/dalfopristin, vancomycin, and linezolid. The clinician then prescribed vancomycin for anti-infective treatment, which proved effective. Keywords: S. mitis/oralis, UTI, MDR, phagocytosis.

Analysis of molecular characteristics of CAMP-negative Streptococcus agalactiae strains.

Background: Streptococcus agalactiae can produce CAMP factor, which can promote the ß-hemolysin activity of Staphylococcus aureus, forming an arrow-shaped hemolysis enhancement zone at the intersection of the two bacterial species on a blood agar plate. This characteristic feature of Streptococcus agalactiae has led to the widespread use of the CAMP test as an identification method. Methods: Vaginal/rectal swabs, collected from women at 35-37 weeks of pregnancy, were first inoculated into a selective enrichment broth media, then subcultured onto GBS chromogenic agar and 5% sheep blood agar sequentially. The VITEK-2 automatic identification system and MALDI-TOF MS were initially employed for identification, followed by the CAMP test. CAMP-negative strains underwent 16S rDNA and cfb gene sequence analysis, as well as bacterial multilocus sequence typing. Results: A total of 190 strains were isolated, with 15 identified as CAMP-negative. Further 16S rDNA gene sequence analysis confirmed that all 15 strains were Streptococcus agalactiae. The MLST typing assay revealed that these 15 strains were of the ST862 type. The cfb gene was amplified and electrophoresed, but no specific fragments were found, indicating that these strains lack the CAMP factor due to cfb gene deletion. Antibiotic susceptibility tests demonstrated no resistance to penicillin, ampicillin, vancomycin and linezolid among the GBS strains. However, there are significant differences in resistance rates to tetracycline. Conclusion: This study found that 7.9% of GBS strains isolated from the vagina/rectum of pregnant women were CAMP-negative, suggesting that the CAMP test method or primers targeting the cfb gene should not be used as the sole presumptive test for GBS identification.