17- Chapter 30 Flashcards
What are airborne pathogens?
Aerosols are important for person to person transmission of many infectious diseases
Most pathogens survive poorly on air so can only do short distances
Respiratory infections are different pathogens that characteristically colonize the respiratory tract at different levels (many are gram positive and many are viruses)
Slide 4 example
What is streptococcus pneumoniae?
Grows in pairs or shirt chains that cause pneumonia
It’s capsule is a major virulence factor but has vaccines with penicillin
What is streptococcus pyogenes?
How do infections occur?
Commonly found in low numbers in upper respiratory tract of healthy individuals
Gram positive grows in chains
Causes beta hemolysis, strep throat, infections of middle ear, infections of superficial layer of skin, acute skin infections
Slide 8
Infections occur if host defenses are weakened or a new highly virulent strain is introduced
What are the complications of group A streptococcus (GAS) involving lysogenic bacteriophage?
GAS may carry a lysogenic bacteriophage that encodes streptococcal pyrogenic exotoxins that act as superantigens and cause toxic shock syndrome and scarlet fever
How can you diagnose and treat streptococcal diseases?
Culture on blood agar followed by serology and other biochemical tests
Antigen detection - rapid tests
Both GAS and S pneumoniae treatable with antibiotics
What is diphtheria?
How does it spread?
Severe respiratory disease that typically infects children
Caused by corynebacterium diphtheriae
Preventable and treatable
Spreads by airborne droplets and enters through respiratory route
What is pertussis (whooping cough)?
What toxin does it produce and how?
Acute highly infectious respiratory disease caused by bordetella pertussis
School age children
Produce pertussis exotoxin (AB toxin) after attaching to cells of upper respiratory tract
Can be prevent by immunization
Can be tested by antibiotics
What is tuberculosis and Hansen’s disease (leprosy)?
Tuberculosis is caused by mycobacterium tuberculosis
Transmitted by airborne droplets
Hansen’s disease is caused by mycobacterium leprae
Transmitted by respiratory routes and direct contact
All mycobacteria are acid fast due to waxy mycolic acid content of their cell walls
How is TB treated?
How is the spread prevented?
Antimicrobial therapy with isoniazid and other antibiotics
Usually requires a 9 months regimen
Affects synthesis of mycolic acid in mycobacteria
Spread of TB is prevented by hospitalization of patients in negative pressure rooms, face masks and antimicrobial therapy
What is meningitis?
What is meningococcal meningitis?
Inflammation of the meninges, membranes that line the central nervous system, especially the spinal cord and brain
Cause by viral, bacterial, fungal, or protist infections
MM- transmitted airborne, high mortality, occurs in epidemics, treatment using penicillin
Slide 24
What are sexually transmitted infections?
Caused by a variety of bacteria, viruses, protists, and even fungi
Pathogens are generally found in bodily fluids from the genitourinary tract that are exchanged during sex
Men banging men are higher risk
Injection drug users are at higher risk
What is neisseria gonorrhoea?
How is it diagnosed?
Preventable and treatable infection
Can be resistant to antibiotics used for treatment
No vaccine
Gonorrhea is characterized by mild vaginitis, pelvic inflammatory disease, infertility in women and urethras discharge in men
Can be passed mother to child
- Microscopy
- Culture (growth on Thayer Martin medium)
- Nucleus acid amplification tests
Slide 12 graph
What is syphilis?
How is it tested and treated?
Caused by treponema pallium
Can be transmitted with other STIs or mother to child
Having syphilis increases chances of getting HIV
Tested by serology blood tests
Treated by penicillin
Symptoms of syphilis on graph on slide 16
What are the 3 types of syphilis?
- Primary syphilis- painless open sore called chancre (comes weeks to couple months after infection at site where infection entered)
Easily undetected - Secondary syphilis- patchy hair loss, rash on soles of the feet of palms of the hands or anywhere else
Fevers, swollen glands and muscle and joint pain
Can go dormant after 2 years or progress to 3 - Tertiary syphilis- affects the brain, blood vessels, the heart ir the bones
What is chlamydia?
Most prevalent STI worldwide
Nonmotile, gram negative
Unique complex biphasic life cycle which is infectious during only one life stage
Slide 20
Symptoms: infection and inflammation of reproductive tract, urethritis can lead to cervical cancer in women
Infections can be asymptomatic
Can be passed to newborns
What is C. Trachomatis?
Diagnosis and treatment?
Causes chlamydia
Diagnoses by NAATs
Formerly tissue culture, antigen detection assays
Treatment- antibiotics, tetracycline with no resistance
What is herpes simplex 1 virus (HSV-1)?
Infects the epithelial cells around the mouth and lips
Can occasionally affect other parts
Two types: 1 and 2 (above and below the waist)
Spreads by direct contact or saliva
Lessons heal without treatment in 2-3 weeks
Increases risk of HIV transmission because it causes an open sore (HIV is blood transmitted)
What is herpes simplex 2 virus (HSV- 2)?
Infections are associated primarily with anogenital region
Causes painful blisters on penis of male and cervix, vulva, and vagina it females
Most easily transmitted when blisters present
Incurable rn but blisters can be controlled
What is human papillomavirus (HPV)?
Small icosahedral non enveloped DS DNA virus
Can infect different parts of body
Over 100 types
Serious types can lead to cervical, penile, and anal cancers
HPV is one of the most common STIs
Most occur without any symptoms and go away without treatment
Spread skin to skin
Immunization and two HPV vaccines present
What is acquired immunodeficiency syndrome AIDS?
What is HIV?
Caused by HIV
Slides 31 and 32 graphs
Two types of HIV:
HIV-1 more virulent type
HIV-2 less virulent and causes milder disease
Opportunistic infections (pneumonia) are common in AIDS patients
Frequent non microbial disease in aids patients in Kaposi’s sarcoma (atypical cancer)
What does HIV infect?
HIV infect cells that contain the CD4 cell surface protein
Most commonly infected are macrophages and T-helper cells
HIV also interacts with co receptors in target cells
Slides 35 -37
How is HIV diagnosed?
How is it treated?
Serological testing predominates (HIV immunoblot)
RT PCR can detect HIV RNA directly from blood and estimate the number of viruses present
Treated by four classes of drugs that delay the symptoms of AIDS and prolong the life of those infected with HIV
There is no vaccine
What are viral infections?
Most prevalent human infections are caused by viruses
Most viral diseases are acute, self limiting infections viruses are less easily controlled by chemotherapeutic methods
What is measles?
What is rubella (German measles)
Caused by paramyxovirus
Virus enters nose and throat by airborne transmission
Fever cough conjunctivitis rash
Rubella resembles measles but is generally milder and less contagious
Routine child immunization
Caused by RNA virus of the togavirus group
Both not serious now cause of vaccines
What is mumps?
Caused by paramyxovirus like measles
Highly infectious
Spread by air drops
Inflammation of salvors glands
What is influenza?
It is caused by an RNA virus of the orthomyxovirus group
3 different types: A B C
A is most prevalent
Occur annually because of plasticity of influenza genome
Vaccine formulations and immune memory are ineffective against an antigenic shift influenza virus (can result in a pandemic)
What is influenza antigenic drift and antigenic shift?
Antigenic drift- minor change in influenza virus antigens due to gene mutation Antigenic shift- major change in influenza virus antigen due to gene reassortment Slide 8 (3)
