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178 Cards in this Set

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Peptostreptococcus is found in what types of infections?
Lung and pleural space. Soft tissue. Chronic sinusitis and otitis, along with Porphyromonas, Bacteroides and Prevotella.
What is the natural habitat of Bacteriodes, Porphyromonas and Prevotella?
The gut.
What symptoms are associated with myonecrosis?
Deep pain in a muscle. Local edema. Increased pulse rate. Severe toxemia.
What is the treatment for myonecrosis?
Debridement or amputation. Antibiotics. Hyperbaric oxygen.
What species of bacteria usually cause a mixed infection with Bacteroides?
Fusobacteria.
What types of infections are caused by Bacteroides, Prevotella, Porphyromonas and Fusobacterium mixed infections?
Brain abscesses. Aspiration pneumonia. Lung abscess.
What predisposes to development of non-traumatic myonecrosis?
Colonic cancer. Leukemia. Diabetes. Neutropenia.
What is(are) the etiologic agent(s) of whooping cough?
Bordetella pertussis Bordetella parapertussis - disease of lesser severity.
Where is Bordetella pertussis found in the body?
On respiratory mucosal surfaces. Does not go elsewhere.
Is whooping cough of any importance as an infection these days?
Yes. 51 million cases worldwide with 600,000 deaths.
What type of vaccine is currently suggested for immunization against Bordetella pertussis?
An acellular vaccine. The older whole cell vaccine has unwanted side effects.
How is Bordetella pertussis infection spread?
By inhalation of infected aerosols.
Besides toxicities what other drawbacks to use of the whole cell Bordetella pertussis vaccine?
Whole cell vaccine provides protections about 12 years. After that individuals can develop disease that is less severe than whooping cough and spread disease.
What are the clinical findings during the catarrhal phase of Bordetella pertussis infection?
Symptoms much like a mild cold.
What are the clinical findings during the paroxysmal phase of infection with Bordetella pertussis infection?
Development of a dry, nonproductive cough progressing to coughing paroxysms. The whoop is heard during this phase.
How long is the convalescent period in patients with whooping cough?
Can last several months due to severe damage to the respiratory tract.
In patients who die as a result of whooping cough, what is the cause of death?
Secondary bacterial infections causing pneumonia.
How does the tracheal cytotoxin (TCT) of Bordetella pertussis contribute to the pathogenesis of the disease?
Kills the ciliated epithelium and removes the ability of this epithelium to prevent infections of the lower respiratory tract.
What type of toxin is the pertussis toxin and what are its biological activities?
An ADP-ribosylating toxin. Activities: Promotes lymphocytosis, histamine sensitization, enhances insulin secretion.
How does the adenylate cyclase/ hemolysis of Bordetella pertussis contribute to the pathogenesis of the disease?
Increases intracellular cAMP in cells. This causes impaired function of leukocytes.
How does the dermonecrotic toxin of Bordetella pertussis contribute to the pathogenesis of the disease?
Causes ischemic necrosis.
What two molecules of Bordetella pertussis contribute to its ability to adhere to host cells?
The filamentous hemagglutinin; fimbriae.
What problems are encountered in trying to culture Bordetella pertussis from patients?
It has a long incubation period. As the disease progresses, it is less likely that the organism can be cultured.
What is the best way to prevent infection with Bordetella pertussis?
Immunization of children with the acellular vaccine (part of the DaPT vaccine).
What is the etiologic agent of legionaire's disease?
Legionella.
What is the natural habitat for species in the genus Legionella?
Water sources such as tower reservoirs and equipment with water supply lines such as dental equipment.
What two types of clinical syndromes are produced in patients infected with Lenionella?
Pneumonia - predominant form. "Pontiac fever" - flu-like without pneumonia.
What are the Gram stain and morphological features of Legionella?
Gram-negative coccobacillary
Are Legionella infections a problem in the United States?
CDC estimates over 1000 cases per year in the U.S. which is probably an underestimate.
What are the guidelines of the American Association of Public Heath Dentistry regarding maintenance of handpieces and the water supply lines to them?
Fit with check valves to prevent aspiration of dental materials. Run water through handpieces for at least 2 min at the beginning of each clinic day to eliminate standing bacteria.
Describe the pathogenesis of Legionella infection.
Organism probably enters via inhalation. In alveoli, it is phagocytized by alveolar macrophages and multiplies intracellularly. Infected cell ruptures allowing infection of more cells.
What part of the immune system is important for elimination of Legionella infection?
Cell-mediated immunity.
What is done to diagnose Legionella disease?
Culture of the organism on special media - detects about 70% of cases. Direct immunofluorescence - lower sensitivity than culture. Detection of Legionella antigen in the urine - detects about 70% of cases
What is the best way to prevent Legionella infection?
Remove from the environment. Thermal eradication (heat above 140 F) is effective.
Name two different species of Mycobacteria that can cause tuberculosis in the normal host.
M. tuberculosis M. bovis
What is the etiologic agent of leprosy?
Mycobacterium leprae.
Which of the Mycobacteria are important infections in the AIDS population?
Mycobacterium avium complex.
Name two hallmarks of infections due to the Mycobacteria.
Ability to survive within phagocytes. Induction of delayed-type hypersensitivity.
What stain is used to identify the Mycobacteria?
Acid-fast stain.
How is tuberculosis transmitted?
Aerosols.
Has transmission of Mycobacterial infection been documented in the dental clinic?
Yes.
In the patient who has recovered from tuberculosis, can the infection occur again?
Yes, at any time during their life. About 10% will reactivate.
Are the mycobacteria Gram-positive?
No they are neither Gram-positive or Gram-negative.
What are the major virulence traits of the Mycobacteria?
Waxy lipophilic surface prevents entry of antibiotics into the cell. Cord factor - disrupts mitochondria, inhibits PMNs, elicits granuloma formation.
What is the most commonly used diagnostic tool used that detect tuberculosis infection?
The Mantoux test - Delayed-type hypersensitivity skin test with PPD (the TB antigen).
Besides skin testing, what other tests are used for diagnosis of tuberculosis?
Chest x-ray. Culture. Takes 5-6 days with more rapid methods.
How long should treatment for tuberculosis last?
6 months to 2 years.
What is DOT and why should it be used for the management of tuberculosis patients?
Directly Observed Therapy. It is used due to noncompliance of patients.
Multidrug resistance is uncommon among the Mycobacteria.
The correct answer is: False
Name two drugs that can be used to treat Mycobacterial infections.
Rifampin Isoniazid
Is there a vaccine for tuberculosis?
Yes. BCG. Not used in the USA.
What is used for prophylaxis of individuals who have come into contact with tuberculosis?
Isoniazid for 6 to 9 months.
What are the Gram-staining and morphologic characteristics of bacteria that are Enterobacteriaceae?
Gram-negative, motile rods.
Which of the Enterobacteriaceae do not ferment lactose?
Salmonella and Shigella.
Why are members of the Enterobacteriaceae an important consideration to the dental clinic?
Since these organisms are spread by the oral-fecal route it is possible to transmit them in the dental clinic.
What are some common virulence traits of the members of the Enterobacteriaceae?
Adhesins. Motility. Resist phagocytosis. Invade the intestinal epithelium. Endotoxin. Hemolysins produced by some organisms. Iron transport systems Type III secretions systems
What is the target of the alpha- hemolysins produced by the Enterobacteriaceae?
More effective on lymphocytes.
What is the function of the beta hemolysins produced by the Enterobacteriaceae?
They are cell bound and inhibit phagocytosis and neutrophil chemotaxis.
What do the type III secretion systems of the Enterobacteriaceae do?
Target virulence factors to the cytoplasm of the host cell.
What is ETEC?
Enterotoxigenic E. coli - Traveler's diarrhea.
What are the specific virulence factors of enterotoxigenic E. coli?
ST - a heat stable toxin. Increases fluid excretion by mucosal cells in the small intestine. LT - heat labile toxin. Virtually identical to cholera toxin.
What is EPEC?
Enteropathogenic E. coli - causes childhood diarrhea.
What is the specific virulence factor of enteropathogenic E. coli (EPEC)?
A shiga-like toxin.
What type of E. coli is responsible for childhood diarrhea of long duration?
EaggEC - Enteroaggregative E. coli
Which type of E. coli produces a severe dysentery-like illness?
EIEC - enteroinvasive E. coli.
Which type of E. coli is responsible for hemorrhagic colitis in children?
EHEC - enterohemorrhagic E. coli
Which strain of E. coli is associated with eating under cooked meat?
E. coli 0157:H7 - an EHEC type E. coli
Besides gastrointestinal infections, what other infections can be caused by E. coli?
Urinary tract infections by strains that make P fimbriae. Neonatal meningitis by strains that produce the K1 capsular polysaccharide.
What type of illness is caused by Shigella spp.?
Diarrheal illness, associated with toxemia, systemic symptoms with blood and mucus in the stool.
What are the specific virulence factors of Shigella spp.?
Invasins: allow penetration of mucosal epithelial cells. Shiga toxin: inhibits protein synthesis in target cells. Type III secretion system.
What is the most common source of salmonellosis?
Contaminated water or food (especially poultry).
What is the most common form of Salmonella infection?
Gastroenteritis.
What type of Salmonella infection can cause severe and life-threatening disease?
Typhoid fever.
What is the pathogenesis of Salmonella infection?
Organisms multiply in small intestine. Adhere to the jejunum and invade epithelial cells. Transport of organisms to lymph nodes. Ingestion of organisms by phagocytes with multiplication of the organism intracellularly. Organisms make their way into the bloodstream and seed the RES.
What are the virulence traits of Salmonella?
Invasins : aid in penetration of epithelial cells. Endotoxin. Resistance to intracellular killing. Vi antigen - inhibits phagocytosis, inhibits serum bacteriocidal activity. Type III secretion. Carrier state.
What type of infection is caused by Yersinia enterocolitica?
Enterocolitis. Exudative pharnyngitis.
What is the reservoir for Yersinia spp.?
Domesticated animals.
What is the etiologic agent of the plague?
Yersinia pestis.
What are the Gram stain and morphologic characteristics of Campylobacter spp.?
Gram-negative comma-shaped (may be called "gull winged")
How is man infected with Campylobacter jejuni?
Consumption of contaminated food and water.
What is the most prevalent food-borne illness in the USA?
Campylobacter jejuni
What types of extraintestinal infections can be caused by Campylobacter fetus?
Enteric. Meningitis. Septic arthritis. Salpingitis. Lung abscess.
What is the specific virulence factor of Campylobacter fetus?
S layer of the organism blocks complement and killing by serum.
What is the etiologic agent of peptic ulcer caused by a bacterium?
Helicobacter pylori.
What is the etiologic agent of cholera?
Vibrio cholerae.
What are the clinical findings in patients with cholera?
High volumes of watery diarrhea. Vomiting. Fluid and electrolyte imbalance leading to dehydration.
How does man become infected with Vibrio cholerae?
From contaminated water.
What are the virulence factors of Vibrio cholerae?
Cholera toxin - causes fluid and electrolyte accumulation in the lumen of the gut.
What Gram-negative organism causes primary lobar pneumonia with a propensity for abscess formation in the lungs of immunocompromised individuals in a hospital setting?
Klebsiella pneumoniae
What is the most important treatment for all diarrheal diseases?
Fluid and electrolyte replacement.
What is the most important preventative measure for gastrointestinal diseases?
Safe water and food supplies.
How can typhoid fever be prevented in those traveling to areas with a high incidence of disease?
A vaccine is available that provides 2-5 years protection.
What is the leading cause of death in burn patients?
Pseudomonas infection.
What is the primary cause of death in cystic fibrosis patients?
Burkholderia cepacia infection.
What severe consequences can happen to women subsequent to having gonorrhea?
Pelvic inflammatory disease. Ectopic pregnancy. Infertility.
What does gonococcal pharyngitis look like?
Patchy edema and erythema of the tonsilar pillars and uvula with discrete vesicles with exudate.
What are the sequelae of systemic meningococcal disease?
Neurological deficits. Amputations due to damage and tissue necrosis.
What is the best way to prevent type b, H. influenzae infections?
Vaccination
What is the best way to prevent infection with non-typeable H. influenzae?
No prophylactic measures are currently available.
What are the Gram staining and morphologic characteristics of the rickettsia?
Gram-negative coccobacilli.
What type of growth conditions do the Rickettsia require?
They are obligate intracellular parasites.
What is the etiologic agent of Rocky Mountain spotted fever?
Rickettsia rickettsii
How are most rickettsia infections spread to humans?
Bite of an arthropod or insect vector
What diseases are caused by Ehrlichia spp?
Human monocytotrophic ehrlichiosis - HME. Human granulocytotrophic ehrlichiosis - HGE.
Why is there a potential for spreading rickettsial disease in the dental clinic?
The agents are found in the bloodstream and therefore could be spread in the clinic if proper infection control practices are not followed.
How do you control the spread or rickettsial diseases?
Control the ectoparasites.
What is the leading cause of community- acquired pneumonia?
Chlamydophila pneumoniae
How is Chlamydia trachomatis infection spread?
Ocular and respiratory secretions.
What is trachoma?
Chronic follicular conjunctivitis due to C. trachomatis infection.
When do pulmonary infections with Chlamydia pneumoniae most often occur?
In late childhood, adolescence and early adulthood.
What are the Gram stain and morphological characteristics of Treponema pallidum?
Slender, tightly coiled helical. Neither Gram-positive or Gram-negative.
What diseases are caused by Chlamydia trachomatis?
Trachoma. Sexually-transmitted disease. Lymphogranuloma venereum.
What type of growth conditions are required by the Chalmydia?
They are obligate intracellular parasites. Therefore, they are grown in tissue culture.
What are the two morphologic forms of the Chlamydiae?
Elementary body (EB) - the extracellular infectious form. Reticulate body (RB) - the noninfectious intracellular replicative form.
What is the life cycle of the Chlamydiae?
EB adheres and is endocytosed. There is no endosomal-lysosomal fusion. EB develop into RB. Growth of RB. RB matures to EB with release of the organisms (EB).
What is the leading cause of preventable blindness in the world?
Chlamydia trachomatis infection.
What is the leading STD in the United States?
Chlamydia trachomatis.
What is the leading cause of preventable infertility in the US?
Chlamydia trachomatis.
What is the leading cause of community- acquired pneumonia?
Chlamydia pneumoniae.
How is Chlamydia trachomatis infection spread?
Ocular and respiratory secretions.
What is trachoma?
Chronic follicular conjunctivitis due to C. trachomatis infection.
When do pulmonary infections with Chlamydia pneumoniae most often occur?
In late childhood, adolescence and early adulthood.
What are the Gram stain and morphological characteristics of Treponema pallidum?
Slender, thightly coiled helical. Neither Gram-positive or Gram-negative.
Can Treponema pallidum be cultured in vitro?
No.
What are the three stages of syphilis?
Primary - chancre occurs at site of inoculation. Secondary - Lesions widespread on the skin and oral cavity with multiple organ involvement. Latent phase Tertiary syphilis - neurosyphilis, cardiovascular, gummatous syphilis (oral lesions).
How do you diagnose syphilis?
Dark-field examination. Serology. Nucleic acid based tests - becoming preferable.
How do you prevent syphilis?
STD - condoms, abstinence, contact tracing. Congenital - diagnosis and treatment of the mother prior to pregnancy.
What is the etiologic agent of Lyme disease?
Borrelia burgdorferi
How is man infected with Borrelia burgdorferi?
Bite of an infected tick.
What lesion is typical in patients with Lyme disease?
Erythema migrans at the site of the initial tick bite. Secondary lesions days to weeks later. Swelling and joint pain in large joints.
How do you prevent Lyme disease?
Control tick bites.
What are the Gram staining and morphological characteristics of the Mycoplasma species?
They do not have a cell wall therefore do not stain by the Gram technique. They have a single cytoplasmic membrane.
What is responsible for up to 50% of the summer pneumonias?
Mycoplasma pneumoniae infection.
How is Mycoplasma pneumoniae transmitted?
Aerosol and close contact.
Why is penicillin not used to treat Mycoplasma infections?
Since they have no cell wall, the antibiotic that targets cell wall synthesis is not effective against this agent.
What is a particular problem concerning spread of Mycoplasma by infected patients?
There is a long period during which the disease is asymptomatic and the patient is infectious. In addition, organisms are shed long after symptoms subside.
What is the major cause of sexually transmitted disease in the U.S.?
Chlamydia trachomatis.
What parasitic organism is considered to be a sexually transmitted disease?
Trichomonas.
What is the etiologic agent of lymphogranuloma venereum?
Chlamydia trachomatis.
What is the etiologic agent of granuloma inguinale?
Calymatobacterium granulomatis
Why is the incidence of syphilis on the rise in recent years?
The AIDS epidemic has caused this.
What is the etiologic agent of chancroid?
Haemophilus ducreyi.
What accounts for the mobility of the syphilis organism?
Axial filaments that work in a manner similar to actin.
What is the morphology of Treponema pallidum?
It is a spirochete.
Can Treponema pallisum organisms be grown in the lab?
No. They are grown in the testicles of rabbits.
What is the primary lesion in syphilis infections?
A painless ulcer called a "chancre".
What method must be used to visualize Treponema pallidum?
Darkfield microscoopy.
What are the clinical characteristics of secondary syphilis?
A generalized skin rash that is maculopapular. Nickle and dime lesions. Mucous patches in the oral cavity.
What occurs during the latent stage of syphilis?
Secondary lesions go away. Organisms will remain, may undergo antigenic variation.
What is tertiary syphilis?
Occurs when secondary syphilis is not treated. "Gummas" (granulomatous) occur in CNS and cardiovascular system. Dementia due to CNS disease.
What are some of the possible consequences of transmission of syphilis from mother to neonate?
Death of the baby. Affects bone and tooth development. Formation of saber shins. Other malformations of bone.
What serologic tests are done to diagnose syphilis?
Rapid Plasma Reagin (RPR) - screening. Fluorescent Treponemal Antibody Absorption Test (FTA-ABS) - confirmatory.
Can serologic testing for syphilis be used during primary syphilis?
Yes. It takes about 90 days for the first lesions to appear and the immune response has developed by this time.
Name the diseases caused by Chlamydiae.
Trachoma - infection of the eye. Inclusion conjunctivitis. Genital tract infection. Lymphogranuloma venereum. Psittacosis. Atypical pneumoniae.
What happens during the primary phase of lymphogranuloma venereum?
The appearance of "herpes-like" vesicles.
What occurs during the secondary phase of lymphogranuloma venereum?
Regional lymphadenopathy in the groin. Lesions can perforate to the skin.
What is characteristic of the tertiary stage of lymphogranuloma venereum?
Fibrotic change in the lymph nodes with abnormal lymphatic drainage.
What is the diagnostic feature of granuloma inguinale disease?
Donovan bodies (clumps of Calymmatobacteria within macrophages and PMNs).
What are Koch's postulates?
To prove that a microorganism is a pathogen: 1. The organism is present in all cases. 2. The organism must be isolated and grown in pure culture. 3. The organism produces same disease in a healthy animal. 4. Organism is re-isolated from the infected animal.
What are Socransky's criteria for a periodontal pathogen?
1. Increased numbers of an organism are found at the infected site. 2. Reduction or elimination correlates with clinical resolution. 3. Demonstration of host response. 4. Organism can cause disease in animal model. 5. Demonstration of virulence factors.
What is a biofilm?
A coordinated community of bacteria containing one or more microorganisms.
What is the name applied to bacteria that grow in the free floating form (such as in laboratory media)?
Planktonic
What are the steps in formation of a biofilm?
1. Conditioning layer - made of glycoproteins 2. Adsorption of bacteria 3. Irreversible attachment of bacteria 4. Extracellular polysaccharide production
Where do biofilms form?
1. On solid substrates 2. On soft tissue surfaces 3. At liquid/air interfaces
What are the advantages for a bacterium to growth in a biofilm?
1. resist surfactants 2. resist phagocytosis 3. resist antibiotics
What is one of the primary molecules that promote the beneficial environment of a biofilm for bacteria?
Extracellular polysaccharide
What is the usefulness of the planktonic mode of growth for the bacterial cell?
1. Allows dissemination of infection. 2. Allows persistence in a dormant form.
What genetic properties of a bacterial cell promote biofilm development?
1. presence of flagella or pili for attachment. 2. extracellular polysaccharide production. 3. quorum sensing for maturation of the biofilm. 4. ability to detach with dispersal of planktonic cells.
What are the health risks due to biofilm formation?
1. Chronic diseases - especially with indwelling devices. 2. They could build-up in dental water lines - but no documentation of this. 3. Impact of biofilms is probably under-recognized.
Where have biofilms been proven to have a health risk?
They build-up in potable water systems.
What are the Canadian recommendations to prevent bacterial accumulation in dental water lines?
1. Avoid heating the water unit. 2. Purge all lines each day. 3. Run high-speed handpieces for 20-30 sec after each patient. 4. Follow manufacturer's instructions re: water source
What are the concerns of the ADA regarding dental water lines?
1. the water is of poor microbiologic quality. 2. dental personnel are exposed to potentially pathogenic aerosols. 3. increasing numbers of patients are immunosuppressed. 4. increasing antibiotic resistance of bacteria.
What are the CDC and ADA recommendations for the numbers of bacterial cultured from dental water lines?
CDC - 500 CFU/ml ADA - 200 CFU/ml
Dental plaque is not a biofilm.
The correct answer is: False
What are the stages of dental plaque formation?
1. Pellicle formation. 2. Initial colonization - Streptococcus and Actinomyces species. 3. Secondary colonization and plaque maturation.
What bacteria are found in tooth- associated plaque?
Gram-positive rods - such as Actinomyces. Gram-positive cocci - such as Streptococci. Apical tooth-associated plaque - has Gram-negative organisms.
What microorganisms are associated with unattached plaque?
Gram-negative rods and cocci. Filamentous organisms. Spirochetes.
What microorganisms are associated with tissue-associated plaque?
Porphyromonas gingivalis. Actinobacillus actinomycetemcomitans. Treponema denticola