MICR 454L Emerging and Re-Emerging Infectious Diseases Lecture 4: N. meningitidis (Chapter 8) Dr. Nancy McQueen & Dr. Edith Porter

Overview N. meningitidis Morphology Growth and metabolic characteristics Virulence factors Diseases Host defenses Diagnosis Culture and biochemical identification Membrane-based dot immunoassay Latex agglutination PCR Therapy and Prevention Threats

Neisseria meningitidis

Gram-negative aerobic diplococci Capnophil Capsule - only some serotypes are associated with epidemics Serotypes A, B, C, W-135, Y US: C, Y, and W-135 (infants: B) 10% of people are healthy nasopharyngeal carriers Humans only known host Transmission via respiratory droplets

Major N. meningitidis Virulence Factors and Their Roles in Host- Pathogen Interaction

N. meningitidis Virulence Factors: Surface Proteins Pili - attachment to nonciliated columnar epithelial cells Class 5 protein (Opa) - attachment and invasion Opc protein - attachment and invasion Class 1, 2 and 3 proteins (por) - porins; invasion; intracellular survival Class 4 protein (rmp) - elicits formation of ineffective blocking antibodies Proteins that detoxify NO Outer membrane proteins

Induced Uptake of N. meningitidis

N. meningitidis: Virulence Factors (2) Lipooligosaccharide (LOS) Comparable to LPS of Gram negative bacilli: endotoxin, but limited sugar residues Adherence and invasion Molecular mimicry of host structures Released in membrane blebs Lipid moiety strongly induces TNF-  Capsule - antiphagocytic; protection from antimicrobial peptides Pili, Opa,LOS, and to a lesser extent, Opc, undergo antigenic variation IgA1 protease

N. meningitidis Virulence Factors: Iron Acquisition and Uptake

Active learning exercise There is a multivalent capsular polysaccharide vaccine currently available for types A, C, Y, and W-135. It has not been possible to develop a capsular vaccine for type B. If you were to try to develop a vaccine to protect individuals from type B infections, what would you target and why?

N. meningitidis: Pathogenesis and Diseases Pathogenesis Attachment to epithelial cells Invasion - bacteria cross the mucosal barrier Bacteria enter the bloodstream ? Entrance into central nervous system Most symptoms are due to the toxic effects of the LOS Diseases Meninogococcal sepsis Abrupt onset High fever Shaking and chills Nausea and vomiting Myalgias and weakness Petechial rash (hallmark of MGC infections).

N. meningitidis: Pathogenesis and Diseases More severe skin lesions as the disease progresses Headache Disease may or may not be accompanied by meninigitis Disease may be chronic, moderate, or fulminant The fulminant form of the disease = Waterhouse Friderichsen Syndrome

Waterhouse-Friderichsen Syndrome Disseminated intravascular coagulation and multiorgan failure (due to released blebs) Septic Shock and bleeding into adrenal glands Widespread purpuric and ecchymotic skin lesions (bleeding into skin and surrounding tissue) Pulmonary insufficiency Death usually within 12 – 48 hours Patients that survive may lose their limbs from tissue necrosis (gangrene of the skin and soft tissues)

N. meningitidis: Pathogenesis and Diseases Bacterial meningitis Abrupt or insidious onset High fever Petechial rash Headache and stiff neck Followed by nausea and vomiting In severe cases there is severe cerebral hyperemia (accumulation of blood) and tissue swelling. May progress to convulsions and coma 10%-14% of cases are fatal For patients who recover 11%-19% have permanent hearing loss or mental retardation

N. meningitidis - Host Defenses Systemic infections occur in individuals lacking serum bactericidal antibodies against the capsular or other outer membrane antigens (Opc). Systemic infections occur in individuals lacking late- acting complement components (C5-C8) or individuals lacking a spleen. Chronic irritation or damage to the respiratory mucosa may be predisposing factors.

N. meningitidis: Diagnosis Plate immediately Is sensitive to temperature extremes and drying Gram stain Often seen intracellularly Identification Culture and biochemicals Plating on selective media Incubation in increased CO 2 Oxidase + Catalase + Oxidative use of glucose and maltose Nitrate - Membrane-based dot immunoassay Latex agglutination PCR

Latex agglutination + Specific antibody bound to latex particles + Specific antigen Agglutination

N. meningitidis: Therapy and Prevention Therapy Ceftriaxon Prophylaxis with rifampin, ciprofloxacin, or ceftriaxone for household and other close contacts Prevention A capsular polysaccharide vaccine to protect disease from groups A, C, Y and W135 is available. A group B vaccine consisting of OM antigens has been developed, but is not available in the United States.

Threats by N. meningitidis Massive epidemic outbreaks in sub-Saharan Africa in the 1990's Emergence since 1995 of serogroups Y, W-135 and X Risk groups Infants and young children Refugees Household contacts of case patients Military recruits College freshmen who live in dormitories microbiologists who work with isolates of N. meningitidis Patients without spleens or with terminal complement component deficiencies

Meningitis Belt in Africa

Take Home Messages N. meningitis is a pathogen that resists phagocytosis, is capable of intracellular survival, and can induce a major LOS mediated inflammatory response with a rapidly fatal outcome. 10% of the populations are carriers. Capsule serotypes A, B, C, W-135, Y can cause epidemics.

Resources The Microbial Challenge, by Krasner, ASM Press, Washington DC, Brock Biology of Microorganisms, by Madigan and Martinko, Pearson Prentice Hall, Upper Saddle River, NJ, 11 th ed, Microbiology: An Introduction, by Tortora, Funke and Case; Pearson Prentice Hall; 9 th ed, Immunobiology, by Janeway,, Travers, Walport, and Shlomchik, Garland Science, 6 th ed, Malak Kotb Genetics of Susceptibility to Infectious Diseases Volume 70, Number 10, 2004 / ASM News Y Bernard Dixon MicrobeLibrary Article: Microbe 2005 Tsai CM, Molecular mimicry of host structures by lipooligosaccharides of Neisseria meningitidis: characterization of sialylated and nonsialylated lacto-N-neotetraose (Galbeta1-4GlcNAcbeta1-3Galbeta1-4Glc) structures in lipooligosaccharides using monoclonal antibodies and specific lectins. Adv Exp Med Biol 491: Gray-Owen SD, et al., Neisseria In Groisman EA (ed.), Principles of Bacterial pathogenesis. Academic Press. San Diego, Calif. pp Bentley SD, et al., Meningococcal genetic variation mechanisms viewed through comparative analysis of serogroup C strain FAM18. PLoS Genet 3(2):e23.

Resources Hauck CR, Meyer TF, 'Small' talk: Opa proteins as mediators of Neisseria-host-cell communication. Curr. Opin. Microbiol. 6(1): Spinosa MR, Progida C, Talà A, Cogli L, Alifano P, Bucci C. (2007) The Neisseria meningitidis capsule is important for intracellular survival in human cells. Infect Immun. Jul;75(7): Epub 2007 Apr 30.