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Case Study Pathogenic Bacteriology 2009. Case # 42 Mamadou Diallo Anne Roberts. Case Summary. 19 year old male student with normal health went to bed with a fever/headache Fever of 40˚c Neck was supple Purpuric rash on legs, trunk and wrists

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Case Study Pathogenic Bacteriology 2009

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Case study pathogenic bacteriology 2009 l.jpg

Case StudyPathogenic Bacteriology2009

Case # 42

Mamadou Diallo

Anne Roberts


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Case Summary

  • 19 year old male student with normal health went to bed with a fever/headache

  • Fever of 40˚c

  • Neck was supple

  • Purpuric rash on legs, trunk and wrists

  • CSF glucose, protein and white blood cell were normal. Blood culture grew the organism.


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Key Information Pointing to Diagnosis

PHYSICAL EXAMINATION

  • 19 years old, student

  • Purpuric rash on legs, wrist, trunk

  • Supple neck

    LABORATORY EXAMINATION

  • CSF glucose, protein, and white blood cell was normal (indicates no bacteria in the CSF fluid)

  • Organism was cultured from blood – Gram Negative Diplococci

  • Low platelet count – indicates the intravascular coagulation


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The Diagnosis for Case #42

  • The patient was diagnosed with bacterial meningitis. The causative agent of this infection was Neisseria meningitidis.

  • The purpuric rash, and Gram stain results were key in the diagnosis of the patient.

  • The finding of a normal CSF profile without evidence of meningitis is atypical. Usually a culture of this fluid will indicate the presence of bacteria.

  • This meant that the organism had disseminated to the blood, where it was cultured.


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Classification,Gram Stain Results, and Microscopic Appearance of N. meningitidis

  • Family – Neisseriaceae

  • Genus – Neisseria

  • Species – meningitidis

  • Gram Negative Diplococci

  • Can be NF of oropharynx in 40%

    of adults. These carriers demonstrate

    no symptoms of meningitis and are

    primary source of spread through

    aerosols, exchange of saliva, etc .


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Diseases and Pathogenesis Caused by Neisseria meningitidis

Pathogenesis:

  • N. meningitidis will attach to epithelial cells of nasopharynx and invade mucous membranes.

  • Bacteria enter blood stream, travel through body where Type IV pili will allow organism to attach to meninges in brain

  • Invasion of the blood stream occurs with individuals deficient in complement component (C5- C8)

  • Lipooligosaccharide (LOS) damages host tissue - hemorrhaging of blood into skin and mucous membranes (purpuric rash)

  • Activity of LOS elicits host inflammatory response

    Diseases:

  • Endemic and epidemic cerebral meningitis

  • Waterhouse Friderichen syndrome – hemorrhaging into adrenal glands

  • Meningiococcal pneumonia

  • Capsular antigens A, B, C, Y, W135 are cause of illness.


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Diagnosis/Isolation/Identification of Neisseria meningitidis

Diagnosis:

Neck pain, purpuric rash

Gram stain of the blood culture

Gram stain from skin lesions

Isolation:

Growth on chocolate agar with 5 - 10% CO2

MTM agar

Identification:

Oxidase – Negative

Catalase - Positive

Nitrate Reduction – Positive

Growth on MTM

Carbohydrate utilization tests - Glucose and Maltose positive


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Therapy, Prevention and Prognosis of Patient Infected with N.meningitidis

Prophylactic strategies in large populations:

  • Administer the tetravalent vaccine to capsular antigens A, C, Y, W135 ( group B vaccine not available in U.S)

  • This is recommended to individuals living in colleges and military settings

    Prophylactic Strategies to exposed individuals:

  • Isolate infected individuals

  • Antimicrobial therapy imperative – fatal if individual goes untreated

  • Penicillin, Chloramphenicol, erythromycin

  • Prophylaxis with rifampin, ciprofloxacin or ceftriaxone for household and others with close contacts.


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Primary Research Article : Neisseria meningitidis

  • Zarantonelli, Maria, et al. 2006. Differential Role of LOS of N. meningitidis in Virulence & Inflammatory Response During Respiratory Infection in Mice, Infection and Immunity, OCT: 5506-5512.

  • Experimental:

    Two mutant strains: double knock out and a single of the gene expressing the LOS from ( N. meningitidis serogroupB)

    • Mutant and wild type strain injected in a mouse model to observe the effect of LOS alteration in meningococcal virulence and its role in inducing an inflammatory response.

  • What did they find?

    • Mutant devoid of LOS unable to invade / persist in the bloodstream

    • Lack of LOS makes N. meningitidis more susceptible to complement mediated bacteriolysis and opsonophagocytosis – mechanisms of early innate defense.

    • The mutant devoid of LOS was also unable to induce an inflammatory response


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Primary Research Article : Neisseria meningitidis

  • In conclusion


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Take Home Message

  • This type of meningitis involves N. meningitidis

  • Typical symptoms: Purpuric rash, supple neck, fever

  • Pathogen can: Disseminate into the blood stream, causing serious complications

  • Diagnostics: Gram stain of CSF/blood culture/skin lesions

  • Therapy is based: Penicillin, Chloramphenicol

  • Prognosis is: Fatal without antimicrobial therapy

  • Prevention: Get Tetravalent vaccine!!!!

  • Transmission: Aerosols, exchange of saliva, etc.

  • Threat: Endemic and epidemic threat among large populations, mental retardation, loss of limbs


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References

Mahon, Connie, Donald Lehman, George Manuselis. Textbook of Diagnostic Microbiology. 3rd Edition. Saunders-Elsevier, St. Louis, Missouri, 2007.

Zarantonelli, Maria, et al. 2006. Differential Role of LOS of N. meningitidis in Virulence & Inflammatory Response During Respiratory Infection in Mice, Infection and Immunity, OCT: 5506-5512.


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