Microbiology - 0425 0426 0427 - Other Bacteria of Medical Importance

• G(+)
• Facultative anaerobic
• Found in intestines
• Drug Resistant (VRE, Vancomycin)
• No potent toxins
• Produces cytolysin: inhibit the growth of other G(+)
• found in patients w/ catheters, causes bacteremia, endocarditis, UTI, wound infection, endodontic infection (root-canal infection)
• Treated w/ aminoglycoside antibiotic w/ cell wall activity: vancomycin, penicillin, ampicillin

• bacteria get to the root-canal via untreated cavity or dentinal tubules, or infected after root-canal treatment
• Ef causes repeated endodontic infections

• spore forming
• aerobic
• +

• anthrax
• soil
• endospore form in the environment

• usually disease of livestock
• animal vaccination effective
• human vaccine not widely spread (low risk, high toxicity)

used as bioweapon; inhaling the airborne spores

• Flu-like sympotoms
• non-productive coughs
• fever/chills
• muscle aches
• malaise

• spores inhaled
• in lungs, macrophage takes up the spore
• Germination inside macrophage
• Grow, rupture, released into bloodstream
• CO2 in blood triggers the bacteria to produce toxin
• may result in death in 3 days of symptoms
• treat w/ ciprofloxacin (Cipro) -> DNA gyrase

• soil, air, water in endospore form
• rice
• food poisoning and ocular infections

spores germinate

• Emetic form: intoxication; by heat stable enterotoxin in contaminated rice. Duration of disease < 6hrs.
• Diarrheal form: infection; by heat labile enterotoxin in contaminated meat, vegetables; loss of water via GI; lasts 20-36hrs.
• No treatment needed

• Physical injury of eye by tool contaminated w/ B. cereus
• Loss of vision within 48hrs
• Louis Braille
• Treatment: vancomycin, clindamycin, ciprofloxacin, gentamycin

• G(+)
• grow between 1-45 C
• Causes listeriosis (food poisoning)
• Intracellular pathogen;
• ActA: uses actin as a tool to propel the bacterium from one cell to an adjacent cell.

• Outbreaks on chicken, turkey, vegetables/fruit
• In neonates, elderly, immunocompromised
• 20-30% mortality rate
• treatment: ampicillin, penicillin, gentamycin

• G(+)
• spore forming
• strictly anaerobic

• Present in soil, water, GI tract of human and animals
• Food poisoning and gas gangrene (myonecrosis)
• Twelve toxins - alpha toxin (lethal toxin, a phospholipase C) - lyses cells such as erythrocytes (massive hemolysis), leukocytes, platelets (bleeding), endothelial cells (increase vascular permeability) -> tissue damage

• after injury and inoculation -> travel to soft tissue -> necrosis
• In muscle, produce gas (H2, CO2) -> expands muscle, cuts off blood supply -> myonecrosis
• 40-100% mortality
• Treatment: surgery - amputation of impactedc tissue/limb to prevent spread; high dose of penicillin

• Antibiotic associated diarrhea, colitis
• Induced by long period of antibiotic therapy for other purposes -> normal flora wiped out -> resistant and becomes dominant
• emerging pathogen due to antibiotic abuse
• treatment: discontinue implicated antibiotic; metronidazole is used to kill it

• Causes tuberculosis (tb)
• discovered by Robert Koch
• Very slow growing, can take about 5-8 weeks to grow on plates or in broth
• Cell coat: not really G+ or G-, acid-fast staining

• 15 million are infected in the US
• Estimated that 20-40% of the population worldwide is infected; Mostly countries in Africa, Asia
• Many of the people who are infected are foreigners or people who travel to other countries and come back
• 2 million deaths per year

• Thick peptidoglycan above cytoplasmic membrane (like G+)
• Structures outside peptidoglycan:
• mycolic acid - responsible for acid-fast staining; about 70-90 carbons in length, contains cyclopropane structure; unlike the polysaccharide in LPS
• Sugar molecules called arabinogalactan connect the mycolic acid structure to peptidoglycan

• Respiratory pathogen engulfed by macrophage
• Mt prevents fusion w/ lysosome and grows inside the phagosome
• Macrophage secrets interleukin under the stim of Mt growth, recruits WBCs
• Eventually encased by WBCs and becomes a granuloma
• Can remain in this stage for years; dormant, aka latent infection, no symptoms
• Under certain conditions (immunocompromise, etc.) becomes active and is released -> active tb

• Antibiotic cocktail over 6-9mo (slow growth; hidden by immune system)
• Isoniazid -> cell wall synthesis
• Rifampin -> RNA synthesis
• Ethambutol -> cell wall synthesis

• G(-)
• spirochete, has periplasmic flagella

• lyme disease (named after Old Lyme, CT)
• No toxins or virulent factors identified

• most prevalent tick-borne disease in US
• Spread via deer tick (up to 50% deer ticks carry Bb; can be found in the environment, not necessarily directly from deer)
• transmission occurs when tick takes bloodmeal (stays on skin 12-24hrs)
• Symptoms:
• Acute: headaches, chills, backache, fatigue, with large rash at site of infection (bull's eye; erythema migrans)
• Chronic: weeks later; arthritis (40-60% patients), neurological involvement (15-20%), cardiac damage (8%); can be dormant in CNS for long time
• Treatment: treated by tetracycline or penicillin early on.

• spirochete
• causes syphilis
• sensitive to environment ( requires mucosal environment, can’t transfer through the air; Has to be through direct contact, as with most STDs; can't pass through unbroken skin, must break epidermal layer)
• Can pass from mother to fetus during pregnancy; congenital syphilis

• Primary: multiplies at site of infection -> lesions; heals spontaneously
• Secondary: spread to mucosal membranes, eyes, joints, bones, CNS -> extensive multiplication -> induce hypersensitivity reaction at site of infection, rash, all over the body
• Tertiary: 50% reach this stage; infection of heart or CNS, inflammation -> can be fatal
• Treatment: penicillin, 7-10d for primary and secondary, several weeks for tertiary

-, coccus

• gonorrhea
• very sensitive to the environment - Easily killed in desiccation, varying temperatures, must live in mucous membranes in the genitourinary tract

• Females- vaginitis (mild symptoms) -> untreated, lead to pelvic inflammatory disease -> can cause sterility
• Males - painful infection of the urethral canal
• In both males and females, if untreated, damage to the heart valves and joint tissues
• Eye infections in newborns (Erythropoietin ointment applied to prevent)
• Penicillin once wiped out the disease
• penicillin resistant strains emerged in 1980s and is widespread
• sensitive to beta-lactams - Cefixime, ceftriaxone
• Quinolones (Cipro/ciprofloxacin)

antigenic switching - switch surface expression profile, new serotype (variant)

Oral contraceptives alter the local mucosal environments by increasing the vaginal pH to mimic pregnancy -> eliminates the lactic acid bacteria -> Ng becomes dominant

• meningitis
• 30% of people carry the bacterium as a natural inhabitant, healthy individuals, in the nasopharynx, no harmful effects, asymptomatic

• inflammation of the meninges, the membrane surrounding the CNS
• Occurs in epidemics -> in closed populations, eg military barracks, dorms
• Since this pathogen can dry out, it requires close contact
• Affects school age students and young adults

• Not known what triggers the bacteria into a pathogenic state
• Respiratory pathogen, transmitted through air droplets-> Colonizes cells of nasopharynx -> enter bloodstream -> meninges

• Headache
• Vomiting
• Stiff neck
• can result in coma and death within hours
• Vaccine in 2005, not long lasting (antigenic switching)
• penicillin and chloramphenicol (no more used in US)

• G-
• found in almost all individuals
• upper respiratory tract infections, otitis media in children, meningitis in children
• First bacteria to have its genome sequenced in 1995

• HiB vaccine
• very effective
• acts against type B Hi, an encapsulated strain, very virulent, causes bacterial meningitis in kids

• G(-)
• Ubiquitous in nature, basically found everywhere (Opportunistic pathogen)
• superbug with a lot of virulence factors, with highly resistant strain
• the most common cause of death in CF patients
• in lungs of cystic fibrosis patients, forms strong biofilms, secrets polysaccharide material, alginate, causes bacteria to become mucoid
• Also associated with burns (w/o skin barrier), pneumonia, ear infections, eye infections, urinary tract infections (UTIs)

• very large genome
• enCodes for all types of antibiotic pumps, contains plasmids, etc

combination including beta-lactams

• Normal inhabitants of GI tract, can cause UTIs and food poisoning
• Escherichia coli
• Salmonella
• Shigella
• Proteus
• Klebsiella

• Common inhabitant of inhabitant
• Produces vitamin K

• O157:H7, Enterohemorrhagic E. coli, EHEC
• O: O-antigen, types of sugars
• 157: 157th O-antigen structure that was discovered
• H7: the seventh type of flagella, based on genetic recombination
• Enterotoxic E. coli, ETEC

• toxins destroy intestinal lining
• invades the kidneys -> lead to permanent renal damage. Leading cause of renal failure in children in the US

• Causes traveller’s diarrhea
• endemic in certain areas - native people are immune to the effects
• resolved with fluids, not treated with antibiotics

• >2500 different O-antigens
• salmonellosis - food poisoning enteric disease -> fever -> systemic
• found in eggs, meat, dairy products

Causes typhoid fever, relatively rare in the US

• More prominent in US
• Transmitted by food handlers through unsanitary conditions - Fecal contamination
• Treatment is not needed for this bacterial infection, usually self limiting

• Lives in poultry, hogs
• The most common foodborne illness in the US
• use flagella to bind to the GI lining
• can pass through 0.4 um filter
• Usually self limiting, but antibiotics are used when there is a serious disease

• comma shaped, with a single polar flagellum
• cholera, a Waterborne disease
• endemic in Asia

• whooping cough/pertussis
• transmits from person to person by coughing
• pertussis toxin (A-B toxin) causes tissue damage - inactivates protein inhibits adenylate cyclase -> increase in cAMP -> increase in respiratory secretions and mucous production -> airway restriction, or pertussis

• characterized by aggressive repetitive cough that often results in vomiting in a cycle
• DPT vaccine - lowered the incidence and severity of the disease
• Macrolides - erythromycin, azithromycin

• dog pathogen, Causes kennel cough in dogs
• Similar to Bp - transmitted by air droplets, coughing
• used as a model system to study the disease
• Not really an animal model, but it’s a naturally occurring disease that mimics the human infection, very useful tool to use

• G+
• found in oropharynx and skin of healthy asymptomatic carriers
• diphtheria
• Transmitted by respiratory droplets

toxoid, the diphtheria toxin treated with formalin, Diphtheria toxin is the most important virulent factor

• Fever
• Malaise
• Sore throat
• Thick pseudomembrane, covers tonsils & palate, consists of bacteria, lymphocytes, fibrin, dead cells, very characteristic purple, dark membrane in the back of the throat, occurs early, As a dentist, can see this before physicians

• Toxin binds to heart cells and neurons via heparin receptor, and kills them (one molecule - one cell, Elongation Factor 2 receptor, protein synthesis, ...)
• Bacteria doesn’t have to enter bloodstream
• toxin has to enter bloodstream
• Anti-toxin therapy: passive immunity to eliminate the toxin, follow up with either penicillin or erythromycin to clear out the bacteria

• G(-), no peptidoglycan has been detected in cell wall (genes exist but not expressed)
• Obligate intracellular parasites
• Elementary body: metabolically inactive, infectious, resistant to harsh conditions (not spore).
• Reticulate body: metablically active, non-infectious.

• Attaches and enters host cell
• In phagosome, EB reorganize into RB
• RB divides and grows
• RB reorganize into EB
• cell rupture and release EB "reverse endocytosis"

• Trachoma -> blindness
• most common STD in US
• genital infection precedes eye infection
• Urogenital infections - nongonococcal urethritis (NGU)

doxycycline, azithromycin, erythromycin; hard to treat/reach

• Obligate intracellular
• Transmitted by ticks, mites, lice, fleas, and rodents carry them
• Causes Rocky mountain spotted fever

• attaches to host endothelial cells
• phagocytosis
• degrades phagosome membrane w/ phospholipase
• grows & replicates in cytoplasm/nucleus of endothelial cells
• damages blood vessel lining cells -> leakage of blood vessels
• hypovolemia & hypoproteinemia due to loss of plasma from blood into tissue
• organ failure

• Have to be exposed to ticks for more than 6 hrs; painless bite.
• Symptoms develop in 2-14d
• High fever, headache, "spotted" rash on wrists, arms, chest, ankles (leakage of blood vessels)
• Tetracycline