Podcast
Questions and Answers
What role do antibiotics play in treating bacterial infections?
What role do antibiotics play in treating bacterial infections?
Which of the following classes of pathogens includes organisms that can cause prion diseases?
Which of the following classes of pathogens includes organisms that can cause prion diseases?
How do Gram staining methods differentiate between types of bacteria?
How do Gram staining methods differentiate between types of bacteria?
Which statement about bacterial growth and replication is true?
Which statement about bacterial growth and replication is true?
Signup and view all the answers
Older patients are at a higher risk of sepsis due to which of the following reasons?
Older patients are at a higher risk of sepsis due to which of the following reasons?
Signup and view all the answers
Which of the following conditions is classified as an AIDS-defining condition associated with HIV?
Which of the following conditions is classified as an AIDS-defining condition associated with HIV?
Signup and view all the answers
Which of these infections is characterized as an opportunistic infection associated with HIV?
Which of these infections is characterized as an opportunistic infection associated with HIV?
Signup and view all the answers
What is a significant characteristic of Mycobacterium tuberculosis in the context of HIV?
What is a significant characteristic of Mycobacterium tuberculosis in the context of HIV?
Signup and view all the answers
Which of the following statements is true regarding opportunistic infections linked to HIV?
Which of the following statements is true regarding opportunistic infections linked to HIV?
Signup and view all the answers
Which of the following is least likely to be classified as a bacterial opportunistic infection in HIV?
Which of the following is least likely to be classified as a bacterial opportunistic infection in HIV?
Signup and view all the answers
Which organism is transmitted by the female Anopheles mosquito and is not a bacterial infection?
Which organism is transmitted by the female Anopheles mosquito and is not a bacterial infection?
Signup and view all the answers
What is a major method to identify bacterial species through staining?
What is a major method to identify bacterial species through staining?
Signup and view all the answers
Which type of bacteria is most likely associated with the proliferation of opportunistic infections in immunocompromised individuals?
Which type of bacteria is most likely associated with the proliferation of opportunistic infections in immunocompromised individuals?
Signup and view all the answers
What condition can Lyme carditis present with as a complication due to bacterial migration?
What condition can Lyme carditis present with as a complication due to bacterial migration?
Signup and view all the answers
What is a significant consequence of a lack of early symptoms in Lyme disease?
What is a significant consequence of a lack of early symptoms in Lyme disease?
Signup and view all the answers
Which diagnostic method is typically followed by Western blot if the initial results are positive for Lyme disease?
Which diagnostic method is typically followed by Western blot if the initial results are positive for Lyme disease?
Signup and view all the answers
Which influenza virus is most commonly associated with severe epidemics and pandemics?
Which influenza virus is most commonly associated with severe epidemics and pandemics?
Signup and view all the answers
What is a key feature of the influenza virus concerning its genetic material?
What is a key feature of the influenza virus concerning its genetic material?
Signup and view all the answers
What role do envelope proteins, such as hemagglutinin and neuraminidase, play in the influenza virus?
What role do envelope proteins, such as hemagglutinin and neuraminidase, play in the influenza virus?
Signup and view all the answers
What symptom can arise from host cell death and sloughing in influenza infections?
What symptom can arise from host cell death and sloughing in influenza infections?
Signup and view all the answers
How does immunization efficacy for influenza vaccinations vary?
How does immunization efficacy for influenza vaccinations vary?
Signup and view all the answers
Study Notes
Infectious Diseases
- Infectious diseases have a significant impact on human health, causing significant illness and death globally.
- The outline for the lectures includes the impact of infectious diseases, host-microbe interactions, different classes of pathogens, pathogen identification, and antimicrobial resistance.
- Specific pathogens discussed include Covid-19, Strep pyogenes, Staph aureus, Strep pneumoniae, Chlamydia trachomatis, Tuberculosis, Neisseria gonorrhea, Clostridioides difficile, Borrelia burgdorferi, Influenza virus, HIV, and Malaria.
- Other considerations are pediatric and geriatric considerations.
- Objectives for Section 1 included understanding the immense impact of infectious diseases on human health, describing aspects of human-microbe interactions (colonization vs. infection, host protection mechanisms, portals of entry, virulence factors, and infection acquisition), and identifying sepsis.
- Top 10 causes of death in low-income and high-income countries were presented in tables based on World Health Organization data.
- COVID-19 excess mortality estimates and reported deaths by WHO region, 2020, were in a graph format.
- Leading causes of death in the U.S., by year, were presented in a table format.
- Highlighted topics for Section 2 included listing the 7 categories of infectious pathogens, describing typical characteristics of pathogens like Bacteria, Viruses, Fungi, and Protozoa, and their respective antimicrobial targets.
Human-Microbe Interactions
- Vaginal delivery initially exposes the neonate to the mother's flora
- Additional exposures, including breathing, eating, and skin contact, are common sources for acquiring various microbes.
- Colonization of the environment via mucosal interfaces: eyes, nose, mouth, pharynx, skin, the gastrointestinal tract, and vagina.
- Pathogens can cause colonization, infection, and can move to other sites, causing infections. Infections can be chronic or fatal.
Mechanisms of Protection from Pathogens
- Normal human flora contribute to the development of the immune system, gastrointestinal function, and inhibiting pathogenic microorganisms' development.
- Skin and mucosa act as barrier functions.
- Each body region has its defense mechanisms and contain antimicrobial compounds like dermcidin and lysozyme.
Complement
- Complement and the membrane attack complex involve proteins that auto-cleave and assemble when exposed to antigens.
- These complexes create holes in bacterial membranes.
Portals of Entry
- Pathogens need a portal of entry and a site of attachment to cause infection.
- Influenza uses hemagglutinin which attaches to sialic acid on respiratory epithelial cells.
- Bacteria can form biofilms on foreign material like implanted heart valves.
Pathogen Virulence Factors
- Mobility and adherence to membranes and migration to other tissue and organs.
- Adaptability to environments (e.g., Helicobacter pylori in acidic stomach).
- Evasion of immune detection or destruction (e.g., Staphylococcus aureus surviving inside neutrophils).
- Toxin secretion and release (exotoxins).
- Endotoxin release, resulting in an overactive immune response.
- Release of superantigens provoking stronger immune reactions.
Host Factors Influencing Pathogen Success
- Certain age groups and general health status are particularly vulnerable.
- Immunosuppression due to disease or medications (like chemotherapy) affects immune defenses.
- Chronic diseases like diabetes interfere with immune defenses against infections.
- The magnitude of the host immune response can sometimes intensify disease severity. This intense inflammatory response can result in septic shock and acute respiratory distress syndrome (ARDS).
Sepsis
- Sepsis is defined as life-threatening organ dysfunction due to a dysregulated host response to infection.
- It includes organ dysfunction (as measured by the SOFA score), clinical suspicion of infection, and response to therapy.
- Septic shock, a more severe form of sepsis, is characterized by life-threatening circulatory, cellular, and metabolic abnormalities. This requires vasopressors to maintain appropriate blood pressure levels and a lactate level greater than 2mmol (or 18 mg/dL).
Epidemiology and Impact of Sepsis
- Sepsis is a major cause of death globally, with millions of incident cases and deaths reported.
- Rates of sepsis and septic shock are increasing in the U.S. and globally overall.
- The reasons include age, immunosuppression, and multidrug-resistant infections.
- Awareness campaigns and earlier detection are improving cases.
Pathogen Classes
- There are trillions of microbial species, but only about 1400 are pathogenic. This includes bacteria, viruses, fungi, yeasts, protozoa, helminths, prions, and algae.
Bacterial Characteristics
- Bacteria are small prokaryotes (1/10th the size of human cells).
- They exhibit diverse shapes (cocci, bacilli, spiral).
- They reproduce by binary fission.
- Bacteria lack a nucleus and have DNA in a nucleoid region.
- Ribosomes are protein translation targets.
- Cell walls influence Gram staining (positive or negative).
- Projections (pili, flagellae) aid adhesion and motility.
Clinical Aspects of Bacterial Infections
- Many bacteria can duplicate quickly via binary fission.
- The presence of bacteria stimulates immune responses from various cells (macrophages, mast cells, neutrophils).
- Exotoxins can damage organs, and some bacterial cell walls (gram-negative) release endotoxins when broken down by immune system components, triggering further responses and symptoms. These factors lead to inflammation and potentially serious conditions like septic shock.
Anti-Microbial Drug Mechanism of Action
- Antimicrobial drugs target differences between prokaryotic and eukaryotic cells, affecting:
- Cell wall synthesis with penicillin and related drugs disrupting cell wall formation.
- Nucleic acid synthesis using sulfonamides, quinolones, and related drugs to block their synthesis.
- Protein synthesis with macrolides, clindamycin, linezolid, and related drugs by blocking ribosomal subunits.
Typical Features of Viruses
- Viruses have nucleic acid cores (DNA or RNA).
- A protein coat called a capsid surrounds the nucleic acid, sometimes an outer membrane.
- Viruses must attach to a host cell and use its machinery to replicate and produce progeny virions.
- Viral progeny virions are released from the cell via budding.
- They are intracellular pathogens, harder for drugs to target.
Antiviral Drugs-Targets
- Antiviral drugs can target viral entry, RNA replication or virion release (e.g., amantadines, ribavirin, oseltamivir, acyclovir, etc).
Key Elements of Fungi and Yeasts
- 200,000 fungal species; ~400 are pathogenic.
- Fungi are eukaryotic, with defined nuclei and organelles; and ergosterol in cell membranes.
- Fungi can be multicellular (branching) or unicellular (yeasts).
Cryptococcus Neoformans
-(Images displayed)
HIV
- HIV is an RNA-based retrovirus.
- Its reverse transcriptase enzyme converts its RNA into DNA, which is then inserted into the host cell's genome.
- Common tests involve P24 antigen & antibody detection & antibody load tracking.
HIV Life Cycle
- HIV enters target cells using GP120 and GP41 proteins.
- The viral RNA's converted to DNA for integration with host DNA.
- New viral components are produced & assembled, followed by release.
Time course of HIV
- Initial stages have a surge in viral load accompanied by CD4 T-cell count decline.
- HIV treatments can lower viral load and increase CD4 T-cell numbers. Without treatment, viral load increases, CD4 count decreases until clinical disease/AIDS sets in.
Malaria
- Malaria is a protozoan infection transmitted by mosquitoes.
- Five pathogenic Plasmodium species cause human malaria.
- The disease's cycle involves sexual and asexual reproduction in mosquitoes and humans.
Pediatric Considerations
- Common childhood infections include viral gastroenteritis and others like Measles (with possible complications).
- Vertical transmission of diseases (e.g., Group B Streptococcus, HIV, Syphilis, Rubella, C. trachomatis) is a significant concern during pregnancy.
- Zika virus infection, toxoplasmosis, and herpes simplex are infections that can be transmitted across the placenta.
Gerontological Considerations
- Community-acquired pneumonia (CAP) or healthcare-associated pneumonia (HCAP) often present atypically in older adults (e.g., mental status changes, incontinence)
Influenza Virus
- Influenza viruses (A, B, C) are enveloped, negative RNA viruses.
- The virus has variations based on proteins (hemagglutinin, neuraminidase).
- Detection methods include NAATs and immunoassays.
- Immunological responses are involved (host cell death & sloughing. Inflammation).
- Viral evolution via shift & drift leads to new variants requiring updated vaccines.
Kaposi's sarcoma
- Associated with herpesvirus 8, characterized by atypical skin lesions.
Tuberculosis (TB)
- Mycobacterium tuberculosis is an important infectious disease.
- It is characterized as a nonmotile, non-spore-forming aerobic bacterium.
- Infected host shows an interaction with pulmonary macrophages.
- Typically presents as chronic disease (though acute presentation is possible)
- Often a latent state exists.
- Diagnosing TB uses a chest x-ray, NAAT, sputum smear, and cultures.
Treatment of TB
- Treatment relies on specific antibiotics such as isoniazid, rifampin, ethambutol, and pyrazinamide (combinations are common to combat resistance).
Question Answers
- Answers to various questions about specific infectious diseases, their pathologies, and implications.
Case Study: Reactivation of TB (The Town Barber)
- This is a case study description focusing in detail on a gentleman's history (exposure, childhood poverty, work, etc.) - leading to his TB diagnosis.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
