Case Study Pathogenic Bacteriology 2009

1. Case StudyPathogenic Bacteriology2009 Case # 42 Mamadou Diallo Anne Roberts

2. 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.

3. 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

4. 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.

5. 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 .

6. 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.

7. 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

8. 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.

9. 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

10. Primary Research Article : Neisseria meningitidis • In conclusion

11. 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

12. 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.