Primary septic arthritis of the knee caused by Neisseria meningitidis serogroup B in an elderly patient. Case report and review of the literature.

PURPOSE: Primary meningococcal arthritis (PMA) represents an uncommon clinical presentation of meningococcal infection, mainly reported among young people. Herein, a case of PMA of the knee in an elderly patient is described. CASE PRESENTATION: On January 2022, an 87-year-old patient arrived at hospital with continuous fever persisting for three days and a picture of pain, swelling, redness, and warmth of her left knee. An arthrocentesis was promptly performed and the inoculated synovial fluid turned positive with numerous Gram-negative diplococci at the microscopic examination. The identification of bacteria was done in 48 h using matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF) MS systems (VITEK®MS-bioMérieux) and standard microbiological procedures (VITEK®2 NH ID card-bioMérieux). Both methods identified the strain as N. meningitidis. The meningococcal isolate belonged to the serogroup B (MenB), Sequence type (ST)-162/clonal complex (cc)162. Two grams of ceftriaxone twice a day were administered for 21 days; than cefditoren pivoxil 400 mg twice a day for further 6 weeks after discharge. In Italy, from 2018 to January 2022, among 135 MenB, 31 MenB/cc162 were identified, of which only the case here reported was associated with an atypical clinical presentation. REVIEW OF THE LITERATURE: A total of 41 cases of PMA caused by N. meningitidis was reported in the literature, but only four occurred in elderly. To our knowledgements, no cases of PMA caused by MenB were previously reported among patients of more than 65 years of age.

Cytographic changes on BC-6800 Haematological Analyzer related to the presence of Candida albicans in peripheral blood. A new tool to suspect candidemia?

BACKGROUND: We studied the quantitative and cytographic changes that the presence of Candida albicans (C. albicans) in peripheral blood (PB) samples causes on the Mindray BC-6800 Haematological Analyzer. METHODS: A simulated in vitro candidemia was obtained by adding a different amount of C. albicans to discarded remnants of PB samples. Quantitative data and cytographic features were evaluated immediately as well as after 120 and 240 min of the yeast addition. A microscopic slides review was even performed at the same time. RESULTS: After yeasts addition, an increase of total leucocytes, neutrophils and basophils have been observed, but these increases are not certainly descriptive of C. albicans presence.Instead, extracellular blastospores cause a false increase in nucleated red blood cells (nRBCs), which appear as a new population in the specific counting channel for erytroblasts (NRBC channel). Regardless of the numbers, C. albicans form a pseudo-erythroblastic cluster in the NRBC channel whose resulting shape is so different than the 'normal' nRBC that it demands a microscopic review. Even cytographic changes related with the neutrophilic phagocytic activity have been observed on leucocyte's differential count citogram (DIFF) of the BC-6800. CONCLUSIONS: Our observations suggest that the results of the BC-6800, which are due to C. albicans' presence, might be useful to speculate earlier diagnosis of sepsis.