Medical Microbiology W8 Flashcards
Approximate percentage with clinically apparent apparent disease : pneumo cystitis jiroveci
0 - if immunity is working well then this won’t make anyone ill
Approximate percentage with clinically apparent apparent disease : EBV (1-5yr old)
1 - if get in 20’s could get glandular fever
Approximate percentage with clinically apparent apparent disease : rubella
50 - 50:50 chance
Approximate percentage with clinically apparent apparent disease : influenza
60
Approximate percentage with clinically apparent apparent disease : whooping, cough, typhoid, malaria, anthrax
> 90
Approximate percentage with clinically apparent apparent disease : gonorrhoea (adult male), measles
99
Approximate percentage with clinically apparent apparent disease : rabies
100 chance
Why do not all infections lead ill illness?
Sometimes you can be infected with no signs or symptoms as some aren’t good at making us ill or we have been vaccinated or we have had it before
Routes of transmission people
Respiratory or salivary spread - COVID-19
Fecal oral spread - natural disperses ie cholera
Venereal spread - STD
Routes of transmission animals
Vector - biting arthropod - mozzie - malaria
Vertebrate reservoir - dog to dog to human - rabies
Vector to Vertebrae reservoir - tick to mouse to human - plague
Horizontal transmission
ie polio
From one person to a group of people by infected air water or food via contact or vectors . Then from that group of people to another group of people.
You can get infected in the week
Vertical transmission
ie HIV, HepB
Infected individual passes it along via milk or sperm/placenta to child who then passes it to the next generation and then to the next generation
From parents to children or unborn baby
pseudomonades
Refer to the pseudomonas genus, a group with the ability to thrive in diverse environments and cause infection
- gram-negative
- Found in soil, water and on plants
- They are opportunistic and causes infection in immunocompromised individuals
- They have acquired antibiotic resistance
- are gram-negative rods
Gram-negative Rod
Elongated bacteria, which tend to not respond to penicillin and detergents
Importance of pseudomonades of humans
They are the quintessential opportunistic pathogen which is a leading cause of hospital acquired infections and develops quite often resistance against antibiotics or detergents
They target weak patient which have weak immune systems or underlining diseases
Whooping cough
Bordatella pertussis
A lot in babies - vaccine rates gone down
Produce toxin to interact with Gai protein ad prevent them being active - affect cell signalling in respiratory tract
bacteria attach to the cilia of the respiratory epithelial cells
Pertussis toxin: Disrupts signaling in host cells, impairing immune defense.
Tracheal cytotoxin: Destroys ciliated epithelial cells, reducing the ability to clear mucus.
Adenylate cyclase toxin: Inhibits immune cells.
Legionnaires pneumonia
Legionella
Likes warm and moist - taps not been run for a while and the water sits in the tap or air on not cleaned
Gonorrhoea
Neisseria gonorrhoeae
Common sexually transmitted disease
Primarily affect mucus membranes of the reproductive tract, but can also infect the throat rectum and eyes
Can be via sexual contact or from baby to mother during childbirth
Some individuals are asymptomatic
Meningitis x2
Neisseria meningitides
Haemophilus influenzae
Doesnt cause influenza. Don’t see a lot in England now
an inflammation of the protective membranes surrounding the brain and spinal cord.
It can be caused by infections (bacterial, viral, fungal, or parasitic), and can also result from non-infectious causes like certain medications or autoimmune diseases.
Bubonic plague
Yersinia pestis
plague has been responsible for at least 3 great pandemics
• Bubonic plague has a 1-15% mortality rate in treated cases - Infected lymph nodes
• Septicemic plague has a 40% mortality rate in treated cases - Blood infection
• Pneumonic plague has 100% mortality if not treated within the first 24 hours of infection - Droplet transmission
Doesn’t make the animal sick
Lyme disease
Borrelia burgdorferi
is spread by bites of ticks three stages of disease:
- distinctive expanding rash at the site of the bite
- dissemination stage with headache and fever
- persistent infection: arthritis, nervous system is affected can be treated with antibiotics
Pneumonia
Streptococcus pneumonia
infection of the lungs that causes inflammation in the air sacs (alveoli).
These air sacs may fill with fluid or pus, making it difficult for oxygen to reach the bloodstream.
Causes of pneumonia related to age
Children
- mostly viral
Adults
- mostly bacterial
Endospore forming bacteria
• produce a unique resting cell called an endospore, endospores can survive for many years
• Gram-positive and usually rod-shaped
• two important genera are Bacillus and Clostridium
• Bacillus: aerobe
Anthrax
Bacillus anthracis
disease of cattle that can be transmitted to humans
Anthrax can enter via intestines, lungs and skin
Is non-contageous
Cholera
Vibrio cholera
Produces toxin (cholera toxin)
Has 2 sub units A and B
Go into GIT cells and replicate and release the toxin here
Toxin then makes it into the cells
Inside cell it binds to GaS
Keeps GaS active to a lot of activating of adenyl cyclase and cAMP production
cAMP leads to activating of CFTR which pumps CL ions out of cell into GIT lumen
Na nad water follow out too nto Lumenso there’s a lot of this in our GIT
= watery diarrhoea
pyogenic cocci
• spherical bacteria which cause various suppurative (pus- producing) infections in animals
• gram positive cocci are the leading pathogens of humans (around 1/3 of all infections)
Staphylococcus aureus
lives on skin and nasal membranes, different strains differ in severity of disease they can induce: boils, pimples, wound infections, pneumonia, toxic shock syndrome; leading cause of infections acquired in hospitals, resistant towards penicillin and many other antibiotics
MRSA - Methicillin Resistant Staphylococcus aureus
usually confined to hospitals, rarely a concern for general public, can be treated by vancomycin (toxic, expensive, has to be given by intravenous infusion)
staphylococcal toxins
• alpha-toxin: produced by most Staph aureus strains that cause human disease, toxin disrupts the smooth muscle in blood vessels and is toxic to many cell types
• beta-toxin: sphingomyelinase C
• delta toxin: wide spectrum of cytolytic activity
• gamma-toxin
• exfoliate toxin: staphylococcus scaled skin syndrome (SSSS)
• enterotoxins: responsible for staphylococcal food poisoning
• toxic shock syndrome toxin-1: TSST-1: 90% of Staph aureus
strains responsible for menstruation-associated TSS produce TSST-1, death in patients with TSS is caused by hypovolemic shock leading to multiorgan failure
diphtheria
Corynebacterium diphtheria
primarily affects the upper respiratory tract (nose and throat) but can also infect the skin.
The disease is characterized by the formation of a thick, grayish pseudomembrane in the throat, which can cause severe complications, including breathing difficulties, heart problems, and nerve damage.
Enterics
Interi bacteria are gram-negative rods with facultative anaerobic metabolism that live in the intestinal tracks of animals
typically harmless and help maintain a healthy intestinal environment. However, certain strains of enteric bacteria may be pathogenic, causing illness in humans
Ie E.coli - 2nd important bacteria in the gut and very few strains are pathogenic
Bacterial cause of diarrhoea E. coli
Enterohaemorrhagic e.coli is verotoxin producing
Outbreak the worldwide
Food and unpasteurised milk
Diagnosis isolate organism from faeces
Salmonella
Most common cause of food associated diarrhoea and widely distributed in animals for a constant source of infection for humans
Diarrhoea from salmonella
Salmonella enters the body through consumption of contaminated food or water
Once ingested the bacteria parts through the stomach and enters the small intestine
They attach to and invade the lining of the intestinal walls, particularly the epithelial cells
Salmonella produces toxins that cause increased fluid secretion and inflammation
The toxin stimulate the intestines to secrete large amounts of fluid and electrolytes into the intestines leading to watery diarrhoea
They also trigger an inflammatory response in the intestines which impairs the normal absorption of water and nutrients and therefore worsening the diarrhoea
The inflammation also leads to death of epithelial cells in the gut lining further contributing to damage and dysfunction of the intestines
Top 10 sexually transmitted diseases (disease and organism)
papillomavirus - genital warts, dysplasia
Chlamydia trachomatis - non-specific urethritis
Chlamydia trachomatis - lymphogranuloma
Candida albicans - vaginal thrush
Trichomonas vaginalis - vaginitis, urethritis
HSV 1 and 2 - genital herpes
Neisseria gonorrhoeae - gonorrhoea
HIV - AIDS
Treponema pallidum - syphilis
Hepatitis B virus - hepatitis
Haemophilus ducreyi - chancroid
spirochetes
bacteria characterized by their unique spiral shape, which gives them the appearance of a corkscrew.
They are motile due to the presence of flagella, allowing them to move in a twisting motion.
This motion enables spirochetes to burrow through viscous environments, such as mucus and tissues, which makes them particularly effective at infecting host organisms.
Syphilis
Treponema pallidum
Syphilis has three stages
-Primary (10 to 60 days after infection)
-Secondary ( last 3 to 6 months)
-tertiary (after 2 to 40 years after infection)
Can be cured with penicillin, chloramphenicol
epidemiology and prognosis of syphilis
Man is the only known host and transmission
Always by direct contact within infectious lesions generally through sexual contact
Highest in sexually active people 20-29 years
If untreated 25% of people will experience one or more relapse within the first four years
Syphilis is mostly irreversible
Chlamydia
Chlamydiae are unable to produce ATP in amount required to sustain metabolism outside of the hostel
Chlamydia is the most prevalent sexual transmitted disease but many people show no symptoms of infection
• Chlamydia trachomatis is also a leading cause of blindness
• Chlamydia pneumoniae is a cause of pneumonia
Bacterial meningitis (pathogen, host, important clinical features and mortality)
Neisseria meningitidis
- children and adolescents
- acute onset (6-24 hours), skin rash
- 7-10%
Haemophilus influenza
- children < 5 years of age
- onset often less acute (1-2 days)
- 5%
Streptococcus pneumoniae
- all ages, but especially children < 2 years of age and elderly
- acute onset may follow pneumonia and/or septicemia in elderly
20-30%
Neonatal meningitis
At or soon after birth
- Less than seven days old
- Risk factors include pre-term delivery, prolonged labour
- Generalised infection, including meningitis and pneumonia
- 60% fatal
- Treatment is blind
In the nursery
- one week to 3 months old
- Lack of maternal antibodies and or poor hygiene in the nursery
- Predominantly meningitis
- 20% fatal
- Prevention with good hygiene and do not allow mothers to handle other babies
Polio virus
highly contagious virus that primarily affects the nervous system.
Transmission is fecal oral
enter the bloodstream and invade the central nervous system, damaging motor neurons.
Herpes simplex virus
Is it very common virus often resulting in sores or blisters on the skin
Two types :
1) HSV-1 (Herpes Simplex Virus Type 1):
- Commonly causes cold sores around the mouth or on the face.
- Can also cause genital herpes, though less commonly.
- Spread through saliva, kissing, or sharing utensils.
2)HSV-2 (Herpes Simplex Virus Type 2):
- Commonly causes genital herpes (sores on the genitals or rectum).
- Spread through sexual contact.
Infect the skin and nerve cells and can reactivate later
Cure exist but anti-viral medications can manage the symptoms and reduce outbreaks
Chicken pox
Contagious and caused by the varicella-zoster virus which is a type of herpes virus.
After infection the virus remains dormant in the body and later reactivate as shingles.
Spread through respiratory droplets or direct contact with fluid from the blisters
Extremely contagious
Epstein-Barr virus
Virus in saliva initiates infection of oral epithelia and spread to B cells in the lymphatic tissue
Virus promote the growth of the cells
T cells kill and limit B cell outgrowth
EBV establishes latency in memory B cell as reactivated when the B cell is activated
Measles
Highly contagious viral disease caused by the measles virus and can affect anyone at any age if they are unvaccinated or lack immunity
Spread through respiratory droplets and is extremely contagious
Site of virus growth for well nourished and malnourished children
Lung - temporary respiratory illness - life-threatening pneumonia
Ear - otitis media - more severe otitis media
Oral mucosa — Kopliks spots - severe ulcerating lesions
Intestinal tract - no lesions - diarrhoea
Pathogenesis of rubella : site of virus growth, result
Respiratory tract - virus shedding symptoms minimal
Skin - rash
Lymph nodes - lymphadenopathy
Joints - arthritis
Placenta/fetus - placentitis, fetal damage
Mumps virus
Cause of acute benign viral parotitis - swelling of salivary glands
primarily affects the salivary glands
Spread throughout the body to the testes another organs
Different hepatitis
A - caused by HepA virus typically spread through contaminated food or water and transmission is physical oral route. Only causes acute infection.. improve hygiene and vaccination is available
B - caused by HepB virus which infects liver cells. Transmission is through the blood semen or other bodily fluids. Many are asymptomatic initially. Can be acute or progressive. Chronic vaccination is highly effective and safe sex practices.
C - caused by HepC virus. Primarily spread through blood contact. Transmission is through sharing needles or blood transfusions and many people have no symptoms for years. It frequently progresses to chronic.. vaccine is available
D - caused by HepD virus and can only infect individuals who are also infected with hepatitis B as it requires HBV to replicate. Transmission through blood and bodily fluids.. can be acute or chronic. HBV vaccination directly prevents HDV.
E - caused by HepE virus. Primarily spread through contaminated water via feacal oral root. Mostly acute. In pre-sanitation and access to include water. There is a vaccine but it is not globally available.
Hepatitis B virus
a DNA virus that infects the liver
Enveloped virus with a partially double-stranded circular DNA genome.
spreads through contact with infected body fluids
Influenza
Also known as flu is a contagious respiratory illness caused by influenza virus. Can be divided into four types ABCD.
A causes the most severe epidemic.
B causes seasonal outbreaks
Transmission by airborne droplets and surface contact
Highly contagious
What does Approximate percentage with clinically apparent apparent disease mean
refers to an estimated proportion of individuals in a given population who show observable and diagnosable symptoms of a specific disease or condition.
