Gram Negative Cocci MCQs

Meningococcal meningitis can spread from one person to other. Because it stays in nasopharynx of person. Now in the given case 2 girls in the same class are already diagnosed with meningococcal meningitis. Their friend must get two dose of conjugate vaccine to prevent getting infection. Incorrect options : Option A is wrong two dose of polysaccharide vaccine. Option C i s wrong Single dose of meningococcal vaccine. Because meningococcal vaccine has two dose not one. Option D is wrong, vaccine can help in spreading of infection. No matter exposure has occurred or not, vaccine can always help. Key Takeaways: Conjugate vaccines (MCV4) are preferred over polysaccharide vaccines (MPSV4). Close contacts of meningococcal meningitis cases require vaccination and antibiotic prophylaxis. Meningococcal conjugate vaccine induces stronger, long-lasting immunity and reduces carriage.

Thayer martin medium is also known as new york city medium. Thayer Martin medium is chocolate agar added with vancomycin, colistin and Nystatin. It inhibits commensal Neisseria Species. Modified New York City medium: Lysed blood agar and lincomycin, colistin, trimethoprim and amphotericin B. Reference: Essentials of Medical Microbiology, by Apurba Sastry and Sandhya Bhat, 3rd edition, page no: 696

Meningococcal polysaccharide vaccines are currently formulated as either bivalent (serogroups A and C) or quadrivalent (serogroups A, C, Y, and Wl35). Dose: 50 µg of each polysaccharide antigen per dose is used, administered as two doses, 2-3 months apart to children of 3-18 months of age or a single dose to older children or adults. No vaccine is available for serogroup B because: Capsule of serogroup B (made up of sialic acid) is less immunogenic. lt is also encephalitogenic due to expression of similar cross reactive antigens on neural cells. Not given below 3 years. Conjugated vaccines can be given below three years. Reference: Essentials of Medical Microbiology, by Apurba Sastry and Sandhya Bhat, 3rd edition, page no: 697

Explanation: Lipopolysaccharide (LPS) , also known as endotoxin , is a unique and defining component of the outer membrane of gram-negative bacteria . It consists of lipid A (the toxic component), core polysaccharide, and O antigen. It is a major virulence factor and potent activator of the host innate immune system. Explanation of other options: Lipoproteins (Option A): Found in both gram-positive (e.g., Braun's lipoprotein) and gram-negative bacteria. Peptidoglycan (Option B): A core component of the cell wall in both gram-positive (thick layer) and gram-negative (thin layer) bacteria. Teichoic acid (Option D): A component found embedded in the thick peptidoglycan layer of gram-positive bacteria; it is absent in gram-negative bacteria. Key Takeaways: LPS (endotoxin) is specific to the outer membrane of gram-negative bacteria. Teichoic acid is specific to gram-positive bacteria.

The deficiency of C5 through C9 components affects the formation of the membrane attack complex (MAC), which is essential for the lysis of certain bacteria, including Neisseria species. This deficiency makes individuals highly susceptible to infections caused by Neisseria, as the MAC is crucial for killing these Gram-negative bacteria. Key Takeaway: Deficiency in C5 through C9 components results in an increased risk of Neisseria infections due to the impaired ability to form the membrane attack complex. Tags: INICET | must know Reference: Shastri, A. (2023). Immunology: Chapter 13on Complement System, pp. 163-167.

Deficiencies of the late common pathway (C5, C6, C7, C8, and C9) are associated with increased Neisseria infections, including Neisseria meningitidis and Neisseria gonorrhoeae. Reference: Ananthanarayan and Paniker's Textbook of Microbiology 10th edition Chapter 14, Pg 131-133

Answer- A. Lymphocytic pleocytosis Normal Bacterial Viral Opening 7-18 >30 Normal or Mildly Increased Pressure Clear, Appearance Turbid Clear Colorless Protein 23-38 Increased Normal to Decreased (mg/dl) 2/3rds Glucose Serum Decreased Normal (mmol/L) Glucose Positive 160-90% of Gram Stain Negative Negative Cases) Glucose CSF: Serum 0.6 0.6 Ratio White Cell cells Predominately Neutrophils Predominately Lymphocytes Count

Each peptidoglycan layer is mucopeptide (murein) chain composed of alternate subunits of N-acetyl muramic acid (NAM) and N-acetyl glucosamine (NAG) molecules. It is present in both Gram positive and negative bacteria. Teichoic acid are polymers of ribitol or glycerol joined by phosphate groups. They are present in Gram positive bacteria. Cell wall teichoic acid: Covalently linked to NAM of cell wall. Lipoteichoic acid: attached to lipids of cell membrane Aromatic and sulphur containing aminoacids are present in Gram negative bacteria. Reference: Ananthanarayan and Paniker's Textbook of Microbiology 12th edition, Pg