Micro test 3- pathogens

Propionibacterium acnes: mode of transmission

skin

Propionibacterium acnes: gram +/-; shape; spore forming?

positive; bacillus; non-spore forming

Propionibacterium acnes: aerotolerance; what does it consume?

aerotolerant anaerobic, consumes sebum

Propionibacterium acnes: site of infection

• Hair follicle

• It secretes enzymes that damage the hair follicle

Propionibacterium acnes: signs/ symptoms

Causes inflammatory lesions (acne)

Propionibacterium acnes: virulence factors

- Hyaluronidase supports invasion by degrading hyaluronan between epithelial cells

- Forms biofilms which protect against antibiotics

Staphylococcus aureus: mode of transmission

sinuses; injury to skin; immunocompromised portals of entry

Staphylococcus aureus: gram + or -; shape

gram positive, cocci, in clusters

Staphylococcus aureus: site of infection

sinuses; skin

Staphylococcus aureus: signs and symptoms

furuncle- pus filled bump (pus and swelling)

carbuncle- pus-filled lesion that is typically deeper than a furuncle. Often develops from multiple untreated furuncles

Staphylococcus aureus: signs and symptoms in infants

Staphylococcal Scalded Skin Syndrome (SSSS), peeling skin

Staphylococcus aureus: signs and symptoms in infants

Staphylococcus aureus: virulence factors (4)

- Hemolysins: enzymes that help destroy red blood cells and liberate hemoglobin

- Coagulases: a plasma-clotting protein that helps protect the bacterial cells

- Leukocidins: helps kill white blood cells and produces pus

- Protein A: inhibits phagocytosis by binding to the constant region of antibodies

Streptococcus pyogenes: Mode of transmission

airborne droplets

Streptococcus pyogenes: gram pos/neg; shape

Gram positive; cocci

Streptococcus pyogenes: site of infection

Mouth, skin, both

Streptococcus pyogenes: signs and symptoms

Swollen uvula, fever, inflammation, dotted patches of pus, strep throat symptoms

Streptococcus pyogenes: virulance factors (3)

- Exoenzymes (secrete Hyaluronidases and destroy protective epithelial barrier. Sectreetes streptokinase (breaks down blood clots, helps spread pathogen)

- Exotoxins (streptolysins that can destroy red and white blood cells, releasing nutrients)

- Erythrogenic toxin (attacks plasma membrane of capillary endothelial cells → scarlet fever)

Mycobacterium tuberculosis: mode of transimission

• Spread by inhalation of respiratory droplets or aerosols from an infected person. Only takes about 10 cells to infect someone (infectious dose)

• Coughing, talking, singing, breathing. Any sort of droplet spread. MTb can survive on moisture droplets for several hours.

Mycobacterium tuberculosis: aerobe

strict aerobe

Where does Mycobacterium tuberculosis reside

reproduces inside and outside macrophages in the lungs

Mycobacterium tuberculosis: site of infection

Respiratory tract, alveoli/lower respiratory tract.

Mycobacterium tuberculosis: infection vs disease

• TB infection (Latent TB) Bacilli have not caused damage, no symptoms. Only 1/10 develop disease

• TB disease: tissue damage, spreads to blood and lymph nodes. More likely to develop if immunocompromised

Mycobacterium tuberculosis: signs and symptoms

- Severe cough

- Coughing up blood

- Prolonged fever

- Night sweats

- Constant tiredness

- Loss of weight and appetite

Mycobacterium tuberculosis: virulence factors

- Mycolic acid cell wall- prevents digestion by macrophages and provides antibiotic resistance. This allows the MTB to grow intracellularly and evade the immune system.

- Urease- converts urea into carbon dioxide and ammonia. Ammonia (a base) prevents acidification of the phagosome, which prevents fusion of phagosome with a lysozyme. 

- Antigen 85 complex. A group of proteins secreted by MTB that bind fibronectin. These proteins help wall-off the bacteria from the immune system.

- Multidrug-resistant tuberculosis (MDR TB): resistant to at least two of the best anti-TB drugs, isoniazid and rifampicin.

- Extensively drug resistant TB (XDR TB): resistant to the above, plus any fluoroquinolone and at least one second-line drug. Patients have less effective treatment options, and cases often have worse treatment outcomes.

Uropathogenic Escherichia coli (UPEC)- mode of transmission

Enter through urinary tract

Uropathogenic Escherichia coli (UPEC): site of infection

urethra, but can ascend to bladder

Uropathogenic Escherichia coli (UPEC): signs and symptoms

- Fever

- Painful urination (Dysuria)

- Puss in the urine (Pyuria)

- Blood in the urine (Hematuria)

P-type pili: Pilus has a receptor for the P antigen (a marker on surface of the perineum and urinary tract); If you have more p antigens on cell surface it may be easier to develop an infection

α-hemolysin: Secreted exotoxin that forms pores - entry point for bacteria

Fimbriae: Similar to pili, short-hairlike appendages, helps with adhesion

Capsule: Poly-saccharide coat that provides layer of protection for bacteria

Iron Receptors: Enable them to get as much iron to allow them to grow in inhospitable conditions

Flagella: For motility

Clamydia trachomatis and Neisseria gonorrhea: mode of transmission

genital, oral, or anal sex or childbirth

Clamydia trachomatis and Neisseria gonorrhea: site of infection

Penis, vagina, mouth, anus, or eye

Clamydia trachomatis and Neisseria gonorrhea: signs and symptoms in females

- Initial symptoms: 60-80% of infected women have none; include: unusual vaginal discharge, pain or a burning sensation when urinating, bleeding between periods, low abdominal pain, sometimes with nausea

- Untreated: can lead to pelvic inflammatory disease which can lead to: Itching and burning, Ectopic pregnancy, Blocked fallopian tubes, Reduced fertility, Chronic pelvic pain, Miscarriage, Premature birth

Clamydia trachomatis and Neisseria gonorrhea: signs and symptoms in males

20% of infected men have no symptoms but are carriers

- Experienced early symptoms: unusual penile discharge, pain or a burning sensation when urinating, testicular swelling

- If left untreated can lead to: Painful inflammation of the testicles, Reduced fertility or sterility, Occasionally arthritic symptoms in joints

Neisseria gonorrhea: virulence factors (4)

- Lots of Pili that help the cells adhere to surfaces 

- Releases Protease-specific for Human antibodies

- Secrets DNA, which increases horizontal gene transfer. (Can easily take up Ab-R genes!)

- Antigenic Variation- causes their pili to constantly change and avoid immune detections

Helicobacter pylori: mode of transmission

• person-to-person contact with saliva, vomit, or stool

• horizontal transfer from mother

Helicobacter pylori: gram + or -; shape

• Gram negative, spiral shaped, multiple flagella at one end

Helicobacter pylori: site of infection

Epithelial cells of the stomach

Helicobacter pylori: signs and symptoms

• 80% of infected people are asymptomatic.

• 20% with symptoms: Bloating, belching or burpin, Nausea, vomiting, abdominal discomfort, Duodenal ulcer, Peptic ulceration, Gastric cancer

Helicobacter pylori: virulance factors

Flagellum (for motility): 5-7 flagella; Located on cell body pole; Moves cell toward regions of higher pH (toward stomach lining and away from stomach acid (chemotaxis)