Microbiology Case Studies
Bacardi Relay, Dulce Cardoso, Traci Hutchison
Hepatitis C
- Binds to liver cell receptors
- HCV virus inserts RNA into liver cell
- HCV RNA mimics liver RNA, produces own viral materials through protein synthesis
- Capsomeres form capsids to protect viral genetic material
- New HCV virus creates bud, releases from liver cell to infect other liver cells
- Cytotoxic cells attack HCV and infected liver cells
- scar tissue from dead liver cells leads to cirrhosis
Hepatitis C
Case Study #2
Mycobacterium avium-intracellulare
- Single stranded RNA virus
- 6 genotypes
- HCV genotype 1 is most common
- Infected individuals typically have only 1 genotype
- Starts acute
- 15-20% of individuals are able to fight off within 6 months of acute episodes
- Many individuals are asymptomatic going years without knowing about infection
- Typically leads to chronic infection
- Primarily baby boomers born between 1945-1965
- Transmission usually via blood
- Sharing needles or syringes during drug use
- Mother-to-child transmission (rare)
- Sexual contact
Falkinham III PhD, Joseph O. Reducing Exposure to Nontuberculous Mycobacteria. National Jewish Health. 2015 September. https://www.nationaljewish.org
Koirala, Janak, MD, MPH, FACP, FIDSA. "Mycobacterium Avium-Intracellulare." Mycobacterium Avium-Intracellulare: Background, Pathophysiology, Etiology. Medscape, 19 Oct. 2016. Web. 06 Dec. 2016.
Daley, Charles MD, Salfinger, Max MD. NTM-TB INSIGHTS: Nontuberculous Mycobacteria (NTM) and Tuberculosis: A Changing of the Guard in the 21st Century? 2015, July. Web. https://www.nationaljewish.org
Mycobacterium Avium Complex (MAC)
- Nontuberulous mycobacterial disorder (NTM)
- Caused by M. avium, M. intracellulare
- Difficult to differentiate between species
- Primarily pulmonary, but can spread systemically
- 58-year-old white male
- Fever, abdominal pain, dark urine
- History of injection drug use, alcohol abuse
- Exam indicates fever, hepatomegaly, icteric
- HBV serology negative
Hepatitis C
Case Study #1
- Frequent mutations of HCV disallow for vaccines
- Cure recently has been approved by FDA in June 2016
- Epclusa
- 95-100% cure rate
- Estimated cost of $890/pill
- 12 week regimen = $74,760
- Pangenotypic inhibitor (targets all 6 genotypes)
- Patients with cirrhosis can take drug
- Discontinue activities that cause additional damage to liver (ex. drinking alcohol)
- 46-year-old male
- HIV positive
- fever, chills, night sweats, diarrhea
- CD4+ T cell count: 50 cells/mcl
- progressive weight loss over several months
- previous treatment for Pneumocystis pneumonia
- Sputum sample positive for acid-fast bacilli
- Blood culture positive for atypical mycobacteria
"Hepatitis C FAQs for Health Professionals." Centers for Disease Control and Prevention. Centers for Disease Control and Prevention, 21 July 2016. Web. 06 Dec. 2016
"Sofosbuvir-Velpatasvir (Epclusa)." Sofosbuvir-Velpatasvir (Epclusa) - Treatment - Hepatitis C Online. University of Washington, 2016. Web. 06 Dec. 2016.
Mycobacterium avium-intracellulare
- Rarely found in immunocompetent individuals
- Patient was immunocompromised due to AIDS
- HIV infection
- CD4+ T cell count: 50 cells/mcl
- Opportunistic infection (Pneumocystis pneumonia)
- Patient was unable to develop cell-mediated immunity
- no activation of macrophages
Mycobacterium avium-intracellulare
- Impermeable outer membrane rich in lipids
- Virulent against antibiotics, chlorine
- Tolerant of acid
- Forms biofilms
- Methylobacterium (pink scum in shower) unable to coexist with NTM
- Methylobacterium still dangerous to immunocompromised individuals
- Microaerophilic
- Survives at 125°F, but not at 130°F
Mycobacterium avium-intracellulare
- Ubiquitous
- Organism can be found in:
- contaminated water
- dust
- dirt
- hot water systems (water pipes)
- birds and farm animals
- Inhalation and ingestion can cause infection
- Not contagious