Microbio UNIT 7 (last exam)

Staphylococcus Background and Morphology

Commensal

grape elike cluster

facultative anaerobe

gram positive

for clinical purpose (Coagulase + and -) —> enzyme that clots fibrin in blood

Commensal

one organism benefits, other is unaffected

Staphylococcus

Staphylococcus epidermis

normal flora

Staphylococcus infections

pimples

boils

Pneumonia

Food poisoning

surgical wound infection

hospital associated infection

scalded skin syndrome

S. aureus

produces yellow colony (aureu = gold)

involved in 16% nosocomial infection caused by microorganisms

60% resistant to antibiotics

most frequent cause of pneumonia

Staphylococcus aureus local infections

pimples

folliculitis

furuncle/ carbuncle

abscesses

outer ear infection

impetigo

S. epidermis

Coagulase negative: causes very common skin infection

pathogenic when skin barrier broken or medical invasive procedures (catheters)

History of drug resistance of S. aureus

Penicillin-resistant S. aureus in hospital (1950s)

Methicillin-resistant S. aureus (MRSA)

S. aureus showed less sensitivity vancomycin- VISA

Vancomycin-resistant S. aureus (VRSA)- 2002

Staphylococcus aureus growth conditions

can grow well under:

high osmotic pressure

low moisture

they can grow in nasal secretions, skin, low moisture food, food with high osmotic pressure (ham, cured meat)

have a yellow pigment which protects them from anti-microbial effects of sunlight

Staphylococcus produces toxins

toxins cause pathogenicity

increases ability to invade body or damage tissue

toxin causes toxic shock syndrome (high fever, vomiting, even death)

produces enterotoxin (in the intestines): most common cause of food poisoning (a superantigen that affects intestine like Vibrio enterotoxin)

Staphylococcus superantigen causes

secretion of fluids, electrolytes from capillaries

thus decreases blood volume

lowers blood pressure

Plasmid and pathogenicity

resistance factors for antibiotics are encoded here

staphylococcal enterotoxin are encoded here

Bacteriophage genes contribute to staphylococcal enterotoxin

plasmid

small circular DNA separate from bacterial chromosome

Neisseria Background and Morphology

Gram Negative Cocci (resembles coffee beans)

inhabit the mucous membranes in mammals

representative of normal microbiota inside the mouth

Pathogenic species of Neisseria

N. gonorrhoeae - gonorrhoea

N. meningitides - meningococcal meningitidis

N. gonorrhoeae

genitourinary tract

N. meningitides

respiratory tract through aerosol

produces endotoxin

Gonorrhea

STI

incubation period for symptoms —> few days

fimbriae attaches to columnar epithelial cells

this causes pus formation due to infiltration of leukocytes

untreated gonorrhea causes endocarditis or arthritis (1%)

Ophthalmia neonatorum

infected infants eyes

can lead to blindness

acquired during vaginal birth

common type of gonorrhea

Pharyngeal gonorrhea

resembles septic sore throat

common type of gonorrhea

Anal gornorrhea

itching, painful, pus

common type of gonorrhea

Vaccines

can prevent serotype A, C, Y, and W - 135 meningococcal infections

purified polysaccharide

development of gonococcal _____ is remote

Gram positive bacilli

non endospore formers

Listeria Background and morphology

gram positive

bacili

opportunist pathogen

commonly found in sewage, stream water, plants, food, soil etc

can grow in temp 4-37 C

depicts tumbling motility

Listeria monocytogenes

listeriosis

caused by eating contacted food (uncooked meat, vegetables, unpasteurized milk and products)

Listeria monocytogenes susceptible population

infants

pregnant women

immunocompromised

Listeria monocytogenes Mechanism of infection

survive within phagocytes and proliferates primary in liver

can escape from phagosome before fusing to lysosome

can move from phagocyte to adjacent cells

Listeria monocytogenes disease in infected adults

mild, sometimes causes mengitidis (50% mortality)

invade bloodstream - sepsis

Listeria monocytogenes disease in fetus and newborns

more severe form

can infect fetus via placenta-abortion, still birth

sometimes manifested in infants after birth (meningitis)

60% mortality infants

Listen-P100

reduces L. monocytogenes in food by using bacteriophages to kill them

Brucella background and morphology

small, non-motile, aerobic, gram-negative

coccobacilli (coccoid rods)

obligate parasites of mammals

causes Brucellosis (Undulant fever)

reservoir - domestic livestock

transmission - contained milk, meat, or animals

Brucella survival and pathogenesis

can survive phagocytosis

it persists in reticuloendothelial system leading to evade host defensed allowing long term survival and replication

disease often becomes chronic and can affect other organs

Brucella

easily airborne and dangerous to handle

a bioterrorism agent

BSL 4 facility

B. abortus

found primarily in cattle but also infects camels, bison, and several other animals

brucella

B. suis

infects swine but is known to infect cattle when kept in close contact with swine herd

humans with close contact with carcasses are any risk

brucella

B. melitensis

causes most serious cases in humans

most commonly found in goats, sheep

brucella

Brucellosis

previously most human cases were attributed to B. abortus (now seldom)

testing and vaccination eliminated brucellosis in cattle (no human vaccines)

most commonly caused by B. melintensis (predominantly in hispanics)

disease endemic in Mexico imported unpasteurized food like soft cheese made form goat milk

Symptoms of Brucellosis

incubation period: 1-3 weeks but could be longer

symptoms depend on stage and organ affected

• rising and falling fever

• Malaise (night sweats)

• muscle aches

Diagnosis of Brucellosis

serological test (but need a definitive test)

ultimate proof (isolation from tissue/ blood of patient)

starts with an interview

no resistance to antibiotics reported

Pseudomonas Background

Aerobic, gram-negative, motile, rods

polar flagella- single or tufts

depicts twitching motlity

common in soil and other natural environemnts

responsible for 1 in 10 nosocomial infection (hospital acquired)

P. aeruginosa

produces soluble blue-green pgiment

in immunocompromised host - infected urinary tracts, burns, wounds, sepsis (blood infection), abscesses, meningitis

species of Pseudomonas

P. syringae

occasional plant pathogen

species of Pseudomonas

bioremediation

What does Pseudomonas use for breaking down harmful pollutants?

Biofilms

P. aeuginsosa can grow inside humans without causing disease until they form _____

can overcome a host’s immune response

can colonies lungs in cystic fibrosis patients and cause deaths

can form on medical devices like catheters, implants etc

Bordetella background

non-motile

obligaeltey aerobic

gram-negative rods (coccobacillus)

virulents strain possess capsule

B. pertussis

pertussis or whooping cough

emerging infectious disease (ones that a re new or changing)

Bordetella Mechanism

specifically attaches to ciliated cells in trachea, first impeding ciliary action and the progressively destroying the cells

this prevents ciliary escalator system from clearing mucus

Bordetella transmission

droplet transmission (a type of contact transmission)

spread in droplet nuclei (mucous droplet) that travel 1 meter and are not regarded as airborne

droplets discharge in air by coughing, sneezing, laughing or talking,

Bordetella incubation period and portal of entry

6-14 days

GI tract

Francisella Morphology

small

Pleiomorphic

gram-negative, bacillus

grows only in complex media enriched with blood or tissue extract

Francisella diseases

Tularemia (F. tularensis)

aka Pahvant Valley plague, rabbit fever, deer fly fever, and Ohara’s fever

Zoonotic disease: transmitted by contact with infected animals (rabbits, squirrels, ticks, and insects)

Francisella route of entry and pathogenesis

penetration of the skin (minor abrasions, ulcer)

swollen lymph nodes containing pus

if not contained leads to sepsis and the infection of multiple organs

Francisella

agent for bioterorism

the infective dose is very small

organisms is dangerous to handle if aerosols are produced

Legionella Morphology

gram negative

bacillis

thin

pleomorphic

flagellated

aerobic

Legionella disease

legionellosis (legionnaires disease)

Legionella growth

grows suitably of artificial media

readily visualized with silver stain

common in streams

Legionella

What microbe is the exception to Koch’s postulate (the pathogen must be isolated forms he diseases hot and grown in a pure culture)

Legionella transmisison

via aerosols - th inhalation of mist droplets containing the bacteria

Legionella Incubation period

up to 2 weeks

Legionella symptoms

initial: flu-like, including fever, chills, and dry cough

advanced:

• GI

• the nervous system

• lead to diarrhea and nausea

• symptoms of pneumonia

Campylobacter Morphology

gram-negatie

microaerophillic vibrios

one polar flagellum

C. jejuni

leading cause of outbreaks of food borne intestinal disease

campylobacter disease

C. fetus

causes spontaneous abortion ind domestic animals

campylobacter disease

Vibrio morphology and background

curved rods

facultative anaerobes

gram-negatives

non-spore formers

motile, polar flagella (monotrichous) with sheath

found mostly in aquatic habitats

V. haemolyticus

less serious gastroenteritis

vibrio pathogenic strain

V. vulnificus

haemolytic

vibrio pathogenic strain

V. cholerae

causes cholera

produces A-B enterotoxin called cholera toxin

vibrio pathogenic strain

vibrio transmission

raw undercooked seafood

contaminated water

vibrio symptoms

5-10% cases develop severe illness

rice watery stool

vomiting

dry mucous membranes

drop in blood pressure

thirst

renal failure

coma

loss of skin elasticity

vibrio diagnosis

stool culture

rectal swab

mycobacterium tuberculosis background

discovered by Robert Koch

waxy coating (mycotic acid) - acid-fast stain

highly aerobic

can survive in dry conditions for weeks

can survive some disinfectants

another strain is called M. leprae

reside in alveolar macrophage

waxy cell wall prevent pahosome-lysosome fusion

can neutralize reactive nitrogen species

mycobacterium tuberculosis diagnosis

sputum test

chest x-ray

mycobacterium tuberculosis symptoms

can stay dominant for decades

10% of infected people develop tuberculosis

can spread form lungs to brain, reproductive system, kidney, bones

• loss of appetite

• fever

• weight loss

• coughing blood

• chest pain

• difficulty breathing

Yersinim pestis background

rod shaped

facultative anaerobe

safety pin appearance

Black Death (plague)

Yersinim pestis transmission

reservoir - several species of rodents

from flea during feeding on an infected animal

animal —> human

human —> human thought skin contact, cough, or sneezing

Yersinim pestis Mode of pathogenesis

resides in lymph nodes and avoid killing by macrophage by escaping phagocytosis

Symptoms of Bubonic plague

after incubation 2-6 days causes swollen lymph nodes (bulbo) most common

Symptoms of pneumonic plague (weaponization)

6 day incubation, spread through aerosolization, respiratory failure, septic shock

Symptoms of Septicemic plague

most dangerous

1-7 days incubation

septic shock an intravascular coagulation

gangrene “Black Death”

Yersinim pestis diagnosis

staining

culturing

Haemophilus Background

aerobic (facultative anaerobe)

previously called bacillus influenzae

gram-negative, rods

opportunistic commensal

six serotypes a-f (based on polysaccharide capsule)

Haemophilus Pathogenesis

affects the immunocompromised

colonizes the upper respiratory region (nasopharynx)

can spread to blood stream

Haemophilus Diseases

Otitis media (children)

adverse conditions with people with bronchitis or CF pateints

Pneumonia

Haemophilus transmission

aerosolization of droplets

Helicobacter pylori background

microaerophilic

gram negative

helix shaped (curved rods)

4-6 lophotrikhous flagella (highly motile)

can form biofilms

Helicobacter pylori pathogenesis

bacteria can be present for decades in the stomach without the patient knowing

causes chronic low-level inflammation in the lining of the stomach

individuals are often asymptomatic

they go through he mucoid epithelium and reside in the inner surface of stomach epithelial cells

Helicobacter pylori disease

duodenal and gastric ulcers

chronic gastritis

esophagus and stomach cancer

reflux esophagitis