Dental Articles Flashcards
Which of the following is CORRECT for obligate anaerobic microorganisms in the oral cavity?
A. They do not exist in this area.
B. Only gram-positive organisms are found.
C. They are normal flora and opportunistic.
D. They are seldom isolated in the laboratory.
E. They can be completely controlled by using antibiotics.
C. They are normal flora and opportunistic.
–
They are part of the normal flora and become pathogenic under certain host conditions (i.e. OPPORTUNISTIC), including lowered resistance and inadequate plaque and calculus control.
Many gingival sulcus and periodontal pathogens are anaerobic. (Obligate anaerobic EXIST in the oral cavity)
They can be either gram (+) or gram (-).
Actinobacillus = gram (-)
Eubacterium = gram (+)
Some of these anaerobes can be isolated in the laboratory, although spirochetes are difficult or impossible.
Bacteria can be controlled to some extent (not completely, that is impossible) through antibiotic use. The mouth is full of microorganisms, and the mouth cannot be made sterile through antibiotic use.
Penicillin = odontogenic infections Streptomycin = some periodontal infections
Malignant epithelial cells have an increased number and wider distribution of which of the following receptors?
A. IL-1 B. Laminin C. Histamine D. Complement E. Immunoglobulin
B. Laminin
When normal cells become malignant, a number of changes can occur in their receptors. The # and distribution of normal receptors may change, and the tumor cell may express new receptors not previously shown = tumor-specific antigens. This concept is the basis for potential immunological treatment of tumors.
Malignant epithelial cells increase number of LAMININ receptors on cell surface.
Chemical carcinogens –> identically genetic cells –> each new tumor has its own UNIQUE tumor-specific antigens.
Oncogenic virus –> new tumor expresses SAME tumor-specific antigen; cells transformed by different viruses exhibit different tumor-specific antigens.
Each of the following is a risk factor in atherosclerosis EXCEPT one.
A. Heredity B. Alcoholism C. Hypertension D. Diabetes mellitus E. Hyperlipoproteinemia
B. Alcoholism
Atherosclerosis (inheritable) = narrowing of arteries due to the accumulation of fatty plaque along the arterial walls.
RISK FACTORS:
- Hyperlipidemia (esp. LDL)
- Hyperlipoproteinemia = exacerbated by high fat diet, especially saturated fat.
- Hypertension (high BP) = faster development and greater degree of atherosclerosis, in particular DIASTOLIC pressure.
- Diabetes = hyaline material may be deposited on aterial walls, reducing blood flow. -
- Increasing age
- Cigarette smoking
- Obesity
- Sedentary Lifestyle
Which of the following is the single MOST numerous group of microorganisms in the oral cavity?
A. Enterococci B. Staphylococci C. Anaerobic streptococci D. Facultative streptococci E. Beta-hemolytic streptococci
D. Facultative streptococci
*Common NDB point.
By far, most bacteria in the mouth are facultative streptococci. These organisms will survive in either aerobic or anaerobic conditions. Chief among these organisms are the non-betahemolytic Streptococci, such as S. mutans, S.salivarius and S. mitor.
Each of the following characterizes a chlamydial infection EXCEPT one.
A. Large numbers of asymptomatic carriers
B. Frequent co-infection with gonorrhea
C. The ability of the organism to survive in the host extracellularly
D. The greater likelihood that younger women will acquire salpingitis
C. The ability of the organism to survive in the host extracellularly (morphological feature, not a clinical characteristic)
Chlamydial infections are NOT characterized by the ability of the organism to survive in the host extracellularly.
Chlamydiae = obligate intracellular parasites that infect birds and mammals.
CHARACTERISTICS:
- Large numbers of asymptomatic carriers
- Frequent co-infection with gonorrhea
- The greater likelihood that younger women will acquire salpingitis
An autosomal dominant trait showing 50% penetrance will be phenotypically expressed in what percent of the offspring?
A. 0 B. 25 C. 33 D. 50 E. 75
B. 25
Penetrance = extent to which a given gene expresses itself
To illustrate, imagine a dominant gene for green hair, G. Both genotypes GG and Gg are expected to phenotypically have green hair. However, due to environmental factors, or due to the effect of other related genes, green hair may not always show phenotypically, even though the individual possesses the dominant G gene. If it actually shows in the appearance of 50% of the individuals who have the appropriate genotype, it is said to have 50% penetrance. The rest of the problem is math. If, for some reason, male parents in a large group express this green trait 50% of the time and female parents also express this green trait 50% of the time, we expect the offspring to express it 50% times 50% or 25% of the time.
Respiratory syncytial virus (RSV) infection differs from influenza infections in that
A. RSV can be treated with amantadine.
B. RSV causes disease primarily in infants.
C. Influenza virus is difficult to transmit.
D. RSV can be prevented with effective vaccines.
E. secretory IgA is not effective in preventing disease.
B. RSV causes disease primarily in infants.
RSV can be treated with amantadine –INCORRECT, Amantadine is effective only in type A influenza infections and acts to decrease symptoms.
Influenza virus is difficult to transmit – INCORRECT, Influenza virus is relatively easy to transmit via inhalation. (RSV is transmitted via aerosolized droplets and fomites).
RSV can be prevented with effective vaccines – INCORRECT, cannot be prevented with effective vaccines. (for Influenza vaccines composed of inactivated virus are designed to elicit immunity against the existing serotypes in the population. Vaccines change from year to year based on the particular serologic determinants of the virus).
Secretory IgA is not effective in preventing disease – INCORRECT, IgA is found in the gut, breast milk, lungs and tears. It would therefore be present in both RSV and influenzae.
Which of the following represent(s) the MOST common source of pulmonary embolism?
A. Esophageal varices B. Endarteritis C. Lymphangitis D. Buerger's disease E. Thrombophlebitis
E. Thrombophlebitis = clots (thrombi) formed within veins, esp. deep leg veins
Pulmonary emboli are formed in the systemic venous system, travel through the R. atrium, R. ventricle, pulmonary artery, and then lodge in the lung.
Esophageal varices = causes severe bleeding Endarteritis = inflammation of the lining of arteries
Lymphangitis = inflammation of the lining of lymph vessels
Buergers disease = involves immune complexes causing damage to arteries and other vessels – often causes thrombosis in legs.
Aflatoxin is produced by
A. Mucor. B. Candida. C. Tricophyton D. Penicillium E. Aspergillus.
E. Aspergillus produces aflatoxin
Aspegillosis is a disease arising from several species of ubiquitous molds. Organisms are normal inhabitants of the soil, and spores are readily disseminated into the air.
MUCOR = often caused by the organisms Rhizopus and Mucor. These molds are ubiquitous on decaying vegetable matter in soil.
CANDIDA = a normal inhabitant of mucocutaneous body surfaces, soil, hospital environments and some foods
TRICOPHYTON = mycotic infection of any keratinous structure of the skin and its appendages.
PENICILLIUM = source of penicillin
Which of the following conditions predisposes to lung cancer by causing squamous metaplasia of bronchial
epithelium?
A. Bronchiectasis B. Bronchial asthma C. Chronic bronchitis D. Bronchial carcinoid E. Pulmonary emphysema
C. Chronic bronchitis
In chronic bronchitis, especially among smokers, normal bronchial epithelium of the pseudostratified ciliated columnar type may be replaced by stratified squamous == loss of protective function –> precancerous.
Bronchiectasis = not precancerous; abnormal dilatation of the bronchi following chronic infection.
Bronchial asthma = not precancerous; narrowing of the bronchi and excess mucus production causing difficulty in breathing.
Bronchial carcinoids = benign lesions of neuroendocrine argentaffin cells of bronchial mucosa
Pulmonary emphysema = not precancerous; involves distention of air spaces with destruction of alveoli.
The likelihood that oral bacteria play an important role in gingival inflammation is evidenced by which of the following?
A. An increase in salivary hyaluronidase
B. An increased number of bacteria in saliva
C. An increase of neutralizing antibodies in saliva
D. A reduction of inflammation with reduction of plaque
D. A reduction of inflammation with reduction of plaque
Evidence that a certain condition is associated with a certain microorganism should include some or all of the conditions of Koch’s postulates.
- The organism should be present when the condition is present, it should be absent when the condition is absent, the condition should be worse when more of the organism is present, and improve when the organism is removed.
Hyaluronidase is not a normal constituent of saliva.
Increased numbers of bacteria in saliva may show something about the condition of the saliva, soft tissues, teeth, salivary glands or many other conditions. It would
not necessarily show anything about the gingiva specifically.
Antibodies in saliva would not be specifically connected to anything occurring within the gingiva.
In addition to Neisseria meningitidis which of the following is a significant cause of meningitis?
A. Streptococcus faecalis B. Streptococcus pyogenes C. Streptococcus pneumoniae D. Staphylococcus aureus E. Staphylococcus epidermidis
C. Streptococcus pneumoniae
Streptococcus pneumoniae = #1 cause in elderly.
Streptococcus faecalis = part of the normal fecal flora; causes urinary tract infections in hospitalized patients; rare cause of subacute endocarditis.
Streptococcus pyogenes (Group A, B-Hemolytic) = obligate human parasite spread person-to-person by respiratory secretion via droplets, direct contact with the skin, or fomites. Clinical manifestations are characterized as suppurative (cause pus) or nonsuppurative (no pus) predominantly involving pharyngitis and various skin infections.
Staphylococcus aureus = common infectious agent of humans; tends to cause localized or toxin-mediated disease. It should not be considered normal flora, but it does transiently colonize the nasopharynx, skin, and vagina of up to 30% of the population.
Staphylococcus epidermis = most commonly a nosicomial pathogen; clinical manifestations are typically related to instrumentation and procedures and include endocarditis and urinary tract infections.
- Which of the following are MOST antigenic?
A. Lipids B. Haptens C. Proteins D. Nucleic acids E. Carbohydrates
C. Proteins (most antigenic substances)
Antigenic substances will produce an immune response.
Antigenic substances:
- Proteins
- Glycoproteins
- Lipoproteins
- Nucleoproteins
Lipids/Nucleic Acids = not usually antigenic unless bound to protein
Haptens = small molecules which contain antibody binding sites, but do not cause an immune response unless they are linked to a protein.
Two types of antibodies are formed:
- Binds to proteins
- Binds to haptens
Carbohydrates = SOME large polysaccharides can activate B cells (thus, antigenic)
Which of the following characterizes victims of fatal, acute carbon monoxide poisoning?
A. Cherry red blood B. Acute renal failure C. Massive liver necrosis D. A hypercoagulability state E. Anemia and generalized white cell depletion
A. Cherry red blood
Carbon monoxide (CO) binds strongly to hemoglobin (Hb), even more strongly than oxygen does. It also bonds in a very slowly reversible way, so that Hb bound to CO stays bound for long periods of time. This Hb has a distinct cherry red color.
CO poisoning results in oxygen starvation to all tissues, but starting with such oxygen-sensitive organs as the brain.
CO poisoning:
- CNS hyperemia
- Edema
- Focal hemorrhages
- Degeneration of basal ganglia.
Which of the following represents the chief complication of mumps in the adult male?
A. Orchitis
B. Prostatitis
C. Glomerulonephritis
D. Chronic nonspecific sialadenitis
A. Orchitis = swelling of testes in male mumps patients
Often develops about 1 week after the parotid gland swelling. More common in older male patients (over 10), and less common in those less than 10.
Prostatitis and glomerulonephritis = not generally associated with mumps.
ACUTE sialadenitis (not chronic) = inflammation of the salivary gland; associated with mumps (paramyxovirus, non-specific)
A fungus that causes systemic disease, most commonly of the lungs, and is characterized by its production of tubercolate chlamydospores in culture is:
A. Microsporum canis. B. Mycoplasma hominis. C. Leptospira pomona. D. Actinomyces israelii. E. Histoplasma capsulatum.
E. Histoplasma capsulatum
Histoplasmosis capsulatum transmission is mediated by airborne inhalation of spores that get deposited in alveoli and spread through lymphatics to the regional lymph nodes.
Clinical manifestations:
- Acute and chronic pulmonary infections that very rarely progress to a disseminated histoplasmosis.
Mycoplasma hominis = sexually transmitted agent; major source of infection in postpartum women.
Leptospira pomona = caused by ingestion or contact through broken skin or mucous membranes with water contaminated by urine from infected reservoirs (dogs, sheep, goats cattle, horses, & rats)
Actinomyces israelii = part of the normal oral flora and are usually pathogenic only after oral trauma.
Which of the following genera is MOST likely involved in bacillary dysentery?
A. Vibrio B. Shigella C. Entamoeba D. Salmonella E. Escherichieae
B. Shigella (involved in bacillary dysentery)
Characterized by:
- Abdominal cramps
- Diarrhea; but, feces contain blood, polymorphonuclear leukocytes, and mucus
*Symptoms are important in differentiating dysentery VS diarrhea (watery feces, most commonly associated with increased secretion of fluid across the mucosal surfaces of the small intestine in response to a toxin or viral infection.)
Vibrio = typically presents with watery [“rice water”] diarrhea (20 liters/day) with the loss of Na+, Cl-, K+, and bicarbonate (HCO3).
Clinical manifestations: Nausea, vomiting, abdominal cramps, metabolic acidosis and hypovolemic shock.
Entamoeba (distractor) = protozoa, thus cannot specifically cause bacillary dysentery. Clinically, the disease may be mild with diarrhea*, abdominal cramps nausea, vomiting, and flatulence.
Salmonella (distractor) = inflammatory diarrhea with fever and variable septicemia. In contrast to Shigella, a large inoculum (> 1 million cells) is needed to survive gastric acid and cause disease - less likely a cause than Shigella.
Escherichieae = most common cause of “traveler’s diarrhea”. There are more than 100 serotypes of Escherichieae that cause this non-inflammatry, secretory diarrhea that is similar to Vibrio, but less severe.
The MOST important viral cause of gastroenteritis in children
A. Rotavirus = major viral cause of gastroenteritis in children less than 2 years old.
Seasonal disease, classically occurs in the fall and winter months.
Echovirus = presents clinically as aseptic meningitis, fever, rash, enteritis, common colds and/or acute hemorrhagic conjunctivitis. Less common symptoms include paralysis, pleurodynia, encephalitis, myocarditis, and respiratory illness.
Rhinovirus = most commonly associated with the common cold. Clinical manifestations: upper respiratory tract irritation, headache, nasal discharge, cough, malaise, chills, and myalgia.
Coxsackievirus = Both types may cause meningitis in humans.
Coxsackievirus Type A (etiologic agent of hand-foot-and-mouth disease) = may cause herpangina, with headache, sore throat, dysphasia, stiff neck, fever, anorexia, and abdominal pain. Discrete vesicles are seen in the oropharynx; cause meningitis
Coxsackievirus Type B = may cause myocarditis, pericarditis, and pleurodynia; cause meningitis
Cytomegalovirus = elicits a mononucleosis illness including fatigue, malaise, tender lymphadenopathy, pharyngitis, fever, headache, and splenomegaly. The majority of these infections are subclinical (with no overt symptoms) but may lead to life-long latent infection; In immunosuppressed patients infection is more severe and marked by fever, adenopathy, leukopenia, hepatosplenomegaly, and myalgias.
A 17-year-old patient has periodontitis involving the anterior teeth with sparse plaque. Which of the following is the probable primary pathogen?
A. Actinobacillus actinomycetemcomitans B. Bactemides forsythus C. Fusobacterium nucleatum D. Porphyromonas gingivalis E. Prevotella intermedia
A. Actinobacillus actinomycetemcomitans (AA)
Adult chronic periodontitis is usually associated with calculus, plaque, inflammation and anaerobic organisms within the periodontal pocket.
Organisms include:
- Bacteroides
- Fusobacteria
- Porphyromonas
- Prevotella.
In this case, however, the young age (17 yo) of the patient, and the absence of plaque and calculus indicate a different disease.
Juvenile periodontitis has a site predilection for incisors and first molars. It is usually very fast in progression, and not associated with high plaque and calculus levels.
Which of the following represents the MOST reliable postmortem indicator of left ventricular cardiac failure?
A. Ascites B. Venous congestion C. Enlargement of the spleen D. Peripheral edema of the ankles E. Chronic passive congestion of the lungs
E. Chronic passive congestion of the lungs
Review the path of blood in the circulatory system: L. atrium (arrived from pulmonary vein from lungs) –> L. ventricle…. Ineffective pumping by the L. ventricle therefore causes higher than normal pressure in the pulmonary vein and lungs - thus, congestion results.
Signs of left-sided failure
- Hypoperfusion of the kidney and brain
- Chronic passive congestion of the lungs
Signs of right-sided failure:
- Edema of ankles
- General systemic VENOUS congestion (fluid back- up, rather than pulmonary)
- Ascites = edematous swelling of the abdomen
