Final – Microbiology Test Questions – Flashcards

Oral cavity is a complex, dynamic ecosystem, containing 400 species of bacteria

·       Dental caries – slow progressive infection of irregular areas of enamel surface

o   Begins with colonization by slime-forming species of Streptococcus & cross adherence with Actinomyces

o   Process forms layer of thick, adherent material (plaque) that harbors masses of bacteria which produce acid that dissolves enamel

o   If plaque is allowed to stay, secondary invaders appear – Lactobacillus, Bacteroides, Fusobacterium, Porphyromonas, Treponema

o   Acid dissolves tooth enamel

Gram negative comma shaped bacteria.

Produces urease, which breaks down urea, producing ammonia that neutralizes stomach acid.

First observed in biopsied stomach tissue samples.

Responsible for 90% of peptic ulcers; cofactors in stomach cancer.

Dogs and Cats carry it.

Gram-Negative, microaeroplilic, spirally curved bacteria.

CJT- enterotoxin- bloody or watery diarrhea.

Culturing requires low O2 and high CO2.

Leading cause of food borne illness in US.

Poultry and beef contaminated.

Gram-negative facultatively anaerobic rods.

Resistant to dyes and bile.

Zoonotic- lives in GI tract of animals.

12-36 hours symptoms.

Invasion of lining of colon, inflammation.

Recovery in a few days

40,000-50,000 reported cases a year.

Gram-negative facultative anaerobic rods.

Strains that produce toxins cause 70% Traveler's Diarrhea.

Causes 50-80% UTI.

Indicator organism for human fecal contamination.

Infectious dose less than 10.

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Minor normal resident of intestine.

Antibiotics kill off normal flora, C. diff overgrows.

Antibiotic associated colitis- diarrhea, inflammed colon.

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Gram positive cocci.

Normally inhabits skin and mucous membranes.

Withstands high salt.

Produces enzymes and toxins.

Diseases: Abscesses, boils, pneumonia, bacteremia, toxic shock syndrome, food poisoning.;

100 degrees C for 30 mins to inactivate.

common airborn bacteria.

Grows in cooked rice, potatoes, and meat.

Spores survive short cooking and reheating.

Spores germinate and produce toxins.

Eating toxins causes nausea, vomiting, cramps.

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Spores in soil, skin, vagina.

Causes gas gangrene in surgical incisions, etc.

Damaged or dead tissue supplies growth factors.

Fermentation of muscle carbs -; gas.

2nd most common cause of food poisoning world wide.

mild illness over in 24 hrs.

Toxin is heat labile.

Most common cause of severe, dehydrating diarrhea among children worldwide.

Causes 50% cases of diarrhea ; death of over 600,000 children worldwide.;

Usually mild in the US.

Causes hospitalization 55,000 kids/yr.

Been detected in many species of domestic animals, wild mammals, and birds.

Vaccine available in Jan 2006

Named for outbreak in Norwalk, Ohio.

Causes 1/3 of all cases of viral gastroenteritis.

Lasts 24-48 hrs.

Virus survives on surfaces for hours.;

Infected person can spread it for 3 days after symptoms.;

Portal of entry: respiratory tract

Multiplies in respiratory tract and lymph nodes.

Self-limited, painful swelling of salivary glands.

Humans are the only reservoir.

40% of infections are subclinical.

300 cases in US/yr.

incubation 2-3 wk, muscle pain.

20-30% of infected males, testes become infected

live attenuated vaccine MMR

Hepatitis= inflammation of the liver

Transmission: Fecal-oral

Treatment: immune globulin

Vaccine: inactivated and attenuated vaccine available.

Chronic: No.

Prevention: Handwashing, vaccine, immune globulin;

Transmission: blood, sex, perinatal

Treatment: interferon and reverse transcriptase inhibitors

Vaccine: recombinant vaccine produced by yeast

Chronic: Yes, 10%

Virus cannot be grown in tissue culture

Recombinant vaccine produced by yeast

Symptoms vary: 50% asymptomatic, early- loss of appetite, low fever, joint pains; later- jaundice; 10% become chronic carriers-; high risk for liver cancer

Transmission: mainly blood, not easily spread through sex, or to fetus

Treatment: interferon and ribavirin

Vaccine: none, rapidly changing virus

Chronic: yes, 80%

HCV cannot be cultured

HCV changes rapidly

Humans only known host.;

Resistant to acid in stomach.

Survives in water and sewage for weeks.

Bad in areas with poor sanitation.

WHO targeting for eradication.

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Transmission: fecal-oral

Multiplication in pharynx ; small intestine-;lymph nodes-;bloodstream.

only 10% infected people develop symptoms.

Death from respiratory failure.

1955- inactivated polio vaccine (IPV)

1963- oral polio vaccine (OPV) attenuated virus

Both are trivalent

Currently in US, only IPV used

Gram positive, endospore forming rods

Food poisoning- endospores are in soil, improper canning does not kill spores.

Die from respiratory or cardiac failure.

Botox

Infant Botulism: dont have well established normal flora, ingest endospores and germinate in the body producing toxins.

C. botulinum does not grow in adult intestines

gram positive endospore forming rods

common in soil and GI tract of animals

causes tetanus or lockjaw

endospores enter through puncture wounds, burns,etc

Vaccine: DPT- a toxoid, inactivated toin

Booster needed every 10 yrs

Gram positive non spore forming

Found in soil, water droplets on ceilings and floor drains.

grows in cold (fridge) temps

Killed during pasteurization and heating

deli meats are most susceptible

is a problem for pregnant women

may infect brain and meninges

stiff neck, meningitis

20% death rate

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Gram negative diplococi

Carried in nasopharynx, invades when resistance is lowered, enters bloodstream and meninges

Symptoms: high fever, chills, lethargy, rash.

in overwhelming infections: shock, coma, and death can follow within several hours.

9-12% die; of those who recover, 20% suffer serious after-effects

Vaccine does not contain live bacteria

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Transmission: involves mosquitoes feeding on birds infected with WNV

Blood, organ transplants, and breast feeding can spread it.

Symptoms: affect the central nervous system

80% will not show symptoms

20% have mild symptoms

1 in 150 develop serious illness

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= proteinaceous infectious particle

NOT a virus

misfolded proteins

resistant to heat, uv light, ionizing radiation

no antibodies, interferon, or inflammation in patient

protein only, no nucleic acid

encoded by a gene on chromosome 20

responsible for vacuoles and abnormal fibers forming in brain

insoluble is detergents; resistant to proteases

slow pathogenesis 1-30yr

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Scrapie in sheep and goats

Bovine spongiform encephalopathies (mad cow disease)

mink, deer, etc

Human- Creutzfeldt-Jakob Disease, Kuru

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If lesions are internal, people may not know they are infected.

Can lead to cervical/penile cancer.

5.5M new genital HPV infections each yr.

Several treatments, no cure.

Vaccine has passed clinical trials and may be available in July 2006.

Caused by Trichomonas vaginalis, a protozoa

Men rarely have any symptoms

Women usually have symptoms within 5 to 28 days of exposure: profuse and itching

5M new cases occur each year

Physician can easily diagnose, treat, and cure

4M

Very small Gram negative obligate intracellular bacteria

Human only reservior

Known as a "silent" disease; 75% women asymptomatic, 50% men asymptomatic

if symptoms occur, they appear 1 to 3 wks after exposure.

Causes eye infections and STD

May cause pelvic inflammatory disease and infertility

Women- bacteria initially infect the cervix and the urethra; might have an abnormal vaginal discharge or a burning sensation when urinating

Infections of the cervix can spread to the rectum

Men have burning and itching around the opening of the penis

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Gram negative diplococci;

have capsules

attach by pili

humans are only reservior

grows in spaces b/t columnar epithellal cells, causes inflammation, pus formation

infection caused by single 1. men 20-30%, Women 60-90%;

Rectal Infection- discharge, anal itching, soreness, bleeding, or painful bowel movements. Rectal infection also may cause no symptoms

Infections in the throat may cause a sore throat but usually causes no symptoms;

Herpes virus family

lesions appear within 1 week

up to 500,000 people get genital herpes each year

Nationwide, 45 million people or 1 out of 5 of the total adolescent and adult population are infected with HSV-2.

Subclinical in 75% of patients

As many as 90% are unaware that they have the virus

Transmission may occur without visible lesions

Neonatal herpes can be very serious;

No cure, treatments reduce recurrences

A spirochete bacteria

Fragile bacteria, cannot survive long outside of host

3 stages with long latent periods:;

a. Primary- 9d-3months-chancre at site of infection

b. secondary-6 months later-fever, headache, sore throat, widely disseminated rash

c. tertiary-10-20 yrs or longer- lesions- gummas on skin ; organs, neural ; cardiovascular symptoms

Can cause serious heart abnormalities, mental disorders, blindness, other neurologic problems, and death.

An infected person who has not been treated may infect others during the first 2 stages, which usually last 1-2 yrs.;

In its late stages, untreated is not contagious.

Passed from mother to child can result in neurological damage.

Currently- efforts are underway to eliminate

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1. Chlamydia

2. Gonorrhea

3. Syphilis

4. Trichomonas