Ch 9 - Infectious Diseases Flashcards
1
Q
What is infectious mononucleosis characterized by?
A
fever, pharyngitis, lymphadenopathy, and circulating atypical lymphocytes.
2
Q
What is infectious mononucleosis caused by?
A
This systemic viral infection is caused by Epstein-Barr virus (EBV),
3
Q
EBV
A
a herpesvirus
4
Q
How is EBV transmitted?
A
through respiratory droplets and saliva and binds to nasopharyngeal cells and B lymphocytes.
5
Q
In developed countries, infectious mononucleosis commonly affects what aspect of the population?
A
teenagers and young adults and is often referred to as the “kissing disease.”
6
Q
How does EBV activate T cells?
A
T cells proliferate in response to activated B lymphocytes and appear in the peripheral blood as atypical lymphocytes.
7
Q
What is commonly seen with EBV?
A
Anemia and thrombocytopenia are common.
8
Q
In underdeveloped countries, EBV infections are typically seen as what? And are associated with what?
A
Subclinical infections in childhood and are associated with an increased risk of Burkitt lymphoma and nasopharyngeal carcinoma.
9
Q
What are the atypical lymphocytes seen circulating in patients with infectious mononucleosis?
A
1) indirectly activated T cells 2) Although EBV infects B cells, the circulating atypical lymphocytes seen in patients with infectious mononucleosis are not immature B cells
10
Q
What is the relationship between the spleen and infectious mononucleosis?
A
Splenomegaly often develops in patients with infectious mononucleosis due to lymphoid infiltration, hyperplasia, and edema. The enlarged spleen may rupture after minor trauma.
11
Q
Burkitt lymphoma and EBV
A
it is associated with Epstein-Barr virus infection in certain parts of the world but is uncommon in North America.
12
Q
N. gonorrhoeae causes
A
an acute suppurative infection of the genital tract
13
Q
N. gonorrhoeae presents as?
A
urethritis in men and endocervicitis in women. It is one of the most common sexually transmitted diseases.
14
Q
Gonorrhea may involve
A
the throat, anus, rectum, epididymis, cervix, fallopian tubes, prostate gland, or joints.
15
Q
Septic arthritis due to N. gonorrhoeae
A
a suppurative inflammation most commonly caused by hematogenous spread, is usually monoarticular, most commonly affecting hips and knees.
16
Q
Primary syphilis presents with what?
A
chancre.
17
Q
Secondary syphilis
A
represents systemic dissemination and proliferation of the spirochete, Treponema pallidum.
18
Q
This secondary syphilis stage is characterized pathologically by?
A
lesions in skin, mucous membranes, lymph nodes, meninges, stomach, and liver.
19
Q
What do the pathological lesions of secondary syphilis show?
A
a perivascular lymphocytic infiltration and endarteritis obliterans.
20
Q
In most cases of secondary syphilis when does the rash appear?
A
2 weeks to 3 months after the primary lesion (chancre) heals.
21
Q
Other lesions associated with secondary syphilis include
A
condylomata lata, follicular syphilis, and nummular syphilis.
22
Q
Chancre is a characteristic lesion of
A
primary syphilis.
23
Q
Dementia, Gummas, Tabes dorsalis are encountered in patients with
A
tertiary syphilis.
24
Q
Anthrax
A
is a necrotizing disease caused by B. anthracis.
25
What does the clinical presentation of anthrax depend on?
the site of inoculation and includes “malignant” pustule, pulmonary anthrax, septicemic anthrax, and gastrointestinal anthrax.
26
What does B. anthracis typically produce?
extensive tissue necrosis at the site of infection, with a mild neutrophilic infiltration.
27
Malignant pustule
is seen in over 95% of all cases of anthrax and represents the cutaneous form of this infectious disease.
28
The person infected with anthrax presents with?
an elevated cutaneous papulae that enlarges and erodes into an ulcer.
29
In an anthrax infection what might local hemorrhagic pustules progress to?
Carbuncles
30
What do cutaneous lesions in an anthrax infection contain?
numerous organisms that release a potent necrotizing toxin.
31
Cholera is
a severe diarrheal illness
32
Cholera is caused by
the enterotoxin of Vibrio choleraE an anaerobic Gram-negative rod.
33
Where does the organism Vibrio Cholerae proliferate and what does it cause?
in the lumen of the small intestine and causes profuse watery diarrhea and rapid dehydration.
34
What might happen if the symptoms of cholera are allowed to persist?
Shock and death can ensue within 24 hours from the onset of symptoms.
35
What is the toxin that is secreted by Vibrio Cholerae?
The AB toxin
36
What does the AB toxin bind to?
Ganglioside GM1 on the intestinal epithelial cells
37
What is stimulated when the AB toxin binds to ganglioside GM1?
Stimulates an increase in intracellular levels of cAMP – leading to water secretion
38
What is the mechanism of action for Vibrio Cholerae?
The AB toxin secreted by the organism binds to ganglioside GM1 on intestinal epithelial cells and stimulates an increase in intracellular levels of cAMP, thereby leading to water secretion.
39
How does the mucosa change upon exposure to Vibrio Cholerae?
The mucosa does not show significant pathologic changes.
40
Enterohemorrhagic E. coli (serotype 0157-H7)
may contaminate meat or milk, causes bloody diarrhea, which can be followed by the hemolytic-uremic syndrome.
41
What does E coli adhere to?
The organism adheres to the colonic mucosa
42
What does E coli releases?
an enterotoxin that destroys epithelial cells.
43
Patients with enterohemorrhagic E coli present with?
abdominal pain, lowgrade fever, and bloody diarrhea.
44
For E. Coli patients what does stool examination show?
leukocytes and erythrocytes.
45
Hemolytic-uremic syndrome is manifested by
microangiopathic hemolytic anemia, thrombocytopenia, and acute renal failure.
46
Under what conditions do Campylobacter jejuni, Salmonella typhi, Shigella dysenteriae and Yersinia pestis present with hemolytic-uremic syndrome?
Although they may be associated with bloody diarrhea, they do not present with hemolytic-uremic syndrome.
47
What is the most common cause of diarrhea in patients on antibiotic therapy (e.g., clindamycin or cephalosporins) who are hospitalized for more than 3 days?
C. difficile
48
Necrotizing enterocolitis
(pseudomembranous colitis) is a disease that may affect the colon in segments or in its entirety.
49
In Necrotizing enterocolitis (pseudomembranous colitis) what happens to the mucosa?
The mucosa is covered by yellow-green, necrotic exudates (pseudomembranes).
50
What are food poisoning and necrotizing entercolitis are caused by?
the enterotoxins of C. perfringens.
51
What happens about 48 hours after the ingestion of C. perfringens contaminated meal?
patients present with abdominal pain and distention, vomiting, and passage of bloody stools.
52
What is the most common cause of gas gangrene following wound infection or septic abortion?
C. perfringens
53
C. tetani produces what?
a potent neurotoxin that causes tetany and generalized muscle spasms.
54
Clostridium botulinum produces what?
a neurotoxin that causes paralysis.
55
Lyme disease
is a chronic infection that begins with a characteristic skin lesion and later variably manifests cardiac, neurologic, and joint disturbances.
56
What is the causative agent of lyme disease?
Borrelia burgdorferi,
57
What is Borrelia burgdorferi?
a large spirochete
58
How is Borrelia burgdorferi transmitted?
from its animal reservoir to humans by the bite of the deer tick (Ixodes).
59
Where does B. burgdorferi reproduce?
at the site of inoculation, spreads to regional lymph nodes, and is eventually disseminated throughout the body.
60
Untreated Lyme disease
it is chronic, with periods of remission and exacerbation.
61
What is Stage 1 Lyme disease characterized by?
erythema chronicum migrans, a skin lesion that appears at the site of the tick bite.
62
What does Stage 3 Lyme disease begin?
months to years after infection
63
What is Stage 2 Lyme disease characterized by?
features migratory musculoskeletal pain and the development of cardiac or neurologic abnormalities (meningitis and facial nerve palsy).
64
What does Stage 3 Lyme disease involve?
joint, skin, and neurologic abnormalities.
65
What happens to over half of the Stage 3 Lyme disease patients?
these patients develop a severe arthritis of the hips and knees, which is indistinguishable from the symptoms of rheumatoid arthritis.
66
Acute meningococcal meningitis
may develop rapidly and is often fatal.
67
Meningococcal sepsis
it is marked by profound endotoxemic shock and disseminated intravascular coagulation, known as Waterhouse-Friderichsen syndrome.
68
What is Waterhouse – Friderichsen syndrome?
Profound endotoxemic shock and disseminated intravascular coagulation
69
Airborne transmission of meningococcal meningitis?
in crowded places (e.g., schools or barracks) can cause “epidemic meningitis.”
70
What are common symptoms for meningococcal meningitis?
Fever, malaise, petechial rash, and adrenal hemorrhages
71
What are the four species of Plasmodium?
P. falciparum, P. vivax, P. ovale, and P. malariae.
72
Can Haemophilus influenza, Klebsiella pneumonia, Streptococcus pneumonia, Treponema pallidumare cause meningitis?
Yes but they are not typically associated with Waterhouse-Friderichsen syndrome.
73
Malaria is
a mosquito-borne illness that infects over 200 million persons per year worldwide.
74
All of Plasmodium organisms infect what?
erythrocytes,
75
Which plasmodium causes the most severe disease?
P. falciparum
76
In “malignant” malaria caused by P. falciparum, what happens?
1) ischemic injury to the brain causes a range of symptoms, including somnolence, hallucinations, behavioral changes, seizures, and even coma.
77
Why are the liver, spleen, and lymph nodes darkened in malignant malaria caused by P falciparum?
by macrophages that are filled with hemosiderin and malaria pigments.
78
Naegleria fowleri
is associated with a fatal type of meningitis.
79
Schistosoma haematobium
is associated with bladder infections but does not cause the hematologic symptoms seen in this patient.
80
What is the most serious manifestation of Aspergillus infection and in what situations does this occur?
invasive aspergillosis, occurring almost exclusively as an opportunistic infection in persons with compromised immunity.
81
What does Aspergillus invade and what does it cause?
readily invades blood vessels and causes thrombosis and local infarction.
82
For Invasive aspergillosis what are found in the walls and lumens of pulmonary vessels?
Branching hyphae (visualized by silver stain)
83
Pneumocystis. jiroveci
1) (formerly P. carinii) was identified in malnourished infants at the end of World War II. 2) It causes progressive, often fatal pneumonia in persons with impaired cell-mediated immunity 3) is one of the most common opportunistic pathogens in persons wit
84
How is P. jiroveci classified?
the organism is now classified with the fungi.
85
How does the infection with P jiroveci begin?
with the attachment of trophozoites to the alveolar lining.
86
In an infection with P jiroveci what happens after the attachment of trophozoites?
1) Trophozoites feed, enlarge, and transform into cysts within the host cells. 2) Eventually, the cysts burst, releasing new trophozoites. 3) Progressive consolidation of the lung ensues.
87
S. pneumonia (pneumococcus) causes what?
pyogenic infections involving the lungs (pneumonia), middle ear (otitis media), sinuses (sinusitis), and meninges (meningitis).
88
What is one of the most common causes of community-acquired pneumonia?
S. pneumonia
89
Consolidation of lung parenchyma typically produces what?
lobar pneumonia
90
What are the four stages of lobar pneumonia?
(1) congestion and edema, (2) red hepatization, (3) gray hepatization, and (4) resolution.
91
Poststreptococcal glomerulonephritis
is a classic immune complex–mediated disease that is associated with nephritic syndrome.
92
What happens during the acute phase of lobar pneumonia?
the alveoli are packed with neutrophils, fibrin, and debris.
93
What are the Infection with two major nonsuppurative complications caused by Streptococcus pyogenes?
namely rheumatic fever and acute poststreptococcal glomerulonephritis.
94
CMV infection
Cytomegalovirus induces interstitial pneumonia in infants and immunocompromised persons.
95
CMV infected alveolar cells show what?
cytomegaly and display a single, dark basophilic nuclear inclusion surrounded by a halo.
96
CMV in children
may be transmitted from mother to child in utero or acquired during delivery.
97
CMV in adults
CMV is transmitted through sexual encounters, blood transfusions, transplantation, and even through the inhalation of infectious viral particles.
98
What symptoms in CMV predominate in symptomatic infants and children?
Central nervous
99
What are the symptoms for CMV in adults?
the virus produces mostly respiratory and gastrointestinal symptoms but does not cause encephalitis.
100
Herpes simplex virus
also features intranuclear inclusions (also surrounded by a clear halo) but does not cause chronic interstitial pneumonia.
101
RSV (respiratory syncytial virus)
is an RNA virus,
102
What is the major cause of bronchiolitis and pneumonia in infants?
RSV
103
What does RSV bronchiolitis or pneumonitis presents with?
expiratory and inspiratory wheezing, cough, and hyperexpansion of both lung fields.
104
For RSV bronchiolitis or pneumonitis what are the expected findings on chest X-ray?
Hyperinflation, interstitial infiltrates, and segmented atelectasis.
105
What do you do for RSV?
The illness is usually self-limited and typically resolves within 1 to 2 weeks.
106
What is the RSV mortality in healthy babies?
Low mortality
107
Influenza A and B are
RNA viruses.
108
Influenza infections are common when?
in the wintertime,
109
What does the severity of the illness from influenza infections depend on?
on the immune status of the individual.
110
What do influenza A and B patients typically present with?
fever, tachypnea, conjunctivitis, and pharyngeal inflammation.
111
In severe cases, what happens in influenza A and B?
patients may develop extreme respiratory distress and prostration.
112
Influenza affects what part of the population?
affects all segments of the population, but severe cases are more commonly seen among the very young and the elderly.
113
Rhinovirus
is the most frequent cause of the “common cold.”
114
Norwalk-like virus and rotavirus cause
diarrhea in children.
115
Infection with respiratory syncytial virus is commonly seen in?
children under 2 years of age.
116
Measles virus is
an RNA virus
117
What does measles virus cause?
an acute, highly contagious, self-limited illness that is characterized by upper respiratory tract symptoms, fever, and rash.
118
The measles virus is transmitted by?
in respiratory droplets and secretions, is primarily a disease of children, but its effects may be particularly severe in adults.
119
For the measles virus what does the skin rash result from?
the reaction of T cells with infected cells of the vascular endothelium.
120
“Koplik spots”
appear on the posterior buccal mucosa and consist of minute gray-white dots on an erythematous base for measles.
121
Measles pneumonia
Although measles is usually a selflimited disease, measles pneumonia (particularly in adults) is a serious malady that may be fatal.
122
Where is the rash for Epstein-Barr virus infection and mumps?
do not present with generalized rash.
123
What is the most common cause of severe diarrhea worldwide?
Rotavirus infection
124
The yeast, Candida albicans, usually cause?
localized infection
125
Psittacosis
is a self-limited pneumonia transmitted to humans from birds.
126
The etiologic agent, Chlamydia psittaci, is present in?
blood, feces, and feathers of infected birds
127
The organism Chlamydia psittaci first infects what?
alveolar macrophages, which carry it to the liver and spleen, where it reproduces.
128
What happens to the organism Chlamydia psittaci after it infects alveolar macrophages, which carry it to the liver and spleen, where it reproduces?
It is distributed hematogenously to produce a systemic infection.
129
Where does C. psittaci reproduce?
in alveolar lining cells,
130
What happens when C. psittaci reproduces in alveolar lining cells causing its destruction?
its destruction elicits an inflammatory response and interstitial pneumonia.
131
Type II pneumocytes
they are hyperplastic and may show characteristic chlamydial cytoplasmic inclusions.
132
Clinically, what does Type II pneumocytes present with?
the disease presents with persistent dry cough, fever, headache, malaise, myalgias, and arthralgias
133
Measles virus and Warthin-Finkeldey giant cells?
fusion of infected cells, producing multinucleated cells termed “Warthin-Finkeldey giant cells.”
134
Warthin-Finkeldey giant cells
These multinucleated giant cells are pathognomonic of measles infections.
135
Cytomegalovirus-infected cells
are very large and contain nuclear and cytoplasmic viral inclusions, but they are not multinucleated.
136
Adenovirus
also features intranuclear inclusions but not multinucleation.
137
Mumps and rubella viruses induce
a mononuclear infiltrate composed of lymphocytes, macrophages, and plasma cells (no giant cells)
138
Legionnaire disease
Legionella pneumophila causes a pneumonia that ranges from mild to a severe life threatening, necrotizing pneumonia
139
Where is Legionella pneumophila found?
in natural bodies of fresh water and survives chlorination, allowing it to proliferate in cooling towers, water heaters, humidifiers, and ventilation systems.
140
When does Legionella pneumonia begin?
when microorganisms enter alveoli, where they are phagocytized by resident macrophages and bacteria multiply within macrophages and are released to infect new macrophages.
141
The disease Legionella pneumonia presents as what?
an acute bronchopneumonia, with a diffuse and patchy pattern of infiltration
142
Tuberculosis
is a chronic, communicable disease in which the lungs are the prime target.
143
Tuberculosis is caused principally by?
Mycobacterium tuberculosis hominis (Koch bacillus), but infection with other species occurs, notably M. tuberculosis bovis (bovine tuberculosis).
144
Primary tuberculosis consists of
lesions in the lower lobes and subpleural space, referred to as the Ghon focus.
145
What is Ghon focus?
lesions in the lower lobes and subpleural space
146
The infection in primary tuberculosis drains to what?
hilar lymph nodes
147
What is Ghon complex?
the combination of Ghon focus and hilar lymphadenopathy
148
Noncaseating granulomas
are a feature of sarcoidosis, among other causes
149
The typical lesion of tuberculosis is a
caseous granuloma
150
What is a caseous granuloma?
a soft core surrounded by epithelioid macrophages, Langhans giant cells, lymphocytes, and peripheral fibrosis.
151
Environmental fungi, such as Rhizopus, Mucor, Rhizomucor, and Absidia species, can produce
necrotizing opportunistic infections that begin in the nasal sinuses or lungs.
152
Mucor is
ubiquitous in the nasal sinuses and invades surrounding tissues.
153
With mucor what happens?
the hard palate or nasal cavity is typically covered by a black crust, and the underlying tissues become friable and hemorrhagic.
154
In mucor what is involved with the fungal hyphae?
They grow into arteries, causing devastating and rapidly progressive septic embolic infarctions.
155
What are the three principal forms of mucormycosis?
rhinocerebral, pulmonary, and subcutaneous.
156
Pulmonary mucormycosis
is usually fatal.
157
What does pulmonary mucormycosis show on microscopic examination?
shows a purulent arteritis with thrombi composed of hyphae
158
In patients who present with a paranasal sinusitis unresponsive to antibiotic treatment particularly those who also have an underlying chronic disease (e.g., diabetes or leukemia) what should be suspected?
Mucormycosis should be suspected
159
Unde what conditions would parainfluenza virus cause thrombosis or infarction?
They don’t cause it
160
Pneumocystis jiroveci pneumonia
noninvasive and causes interstitial pneumonitis
161
H. influenzae
is a Gram-negative coccobacillus
162
What is the leading cause of meningitis and epiglottitis in children worldwide?
H. influenza, a Gram-negative coccobacillus
163
H. influenza infections may also involve
the middle ear, sinuses, facial skin, lungs, and joints.
164
H. influenzae spreads
from person to person in respiratory droplets and secretions.
165
H. influenza causing inflammation of the epiglottis, aryepiglottis sinus, and pyriform recess produces what?
significant airway obstruction, which can be fatal.
166
Since the widespread use of the HiB vaccine in the United States what happened?
invasive disease due to H. influenzae type B in pediatric patients has been reduced by 80% to 90%.
167
Streptococcus pyogenes, S. pneumoniae, and Staphylococcus aureus, now represent a larger proportion of pediatric cases of what?
epiglottitis in the United States.
168
The genus Candida
comprises over 20 species of fungi, which include the most common opportunistic pathogens.
169
Many Candida species are
endogenous human flora.
170
When the normal bacterial flora that limit fungal growth are suppressed what happens?
the yeast converts to an invasive form, eliciting an inflammatory reaction.
171
What does thrush signify?
candidal infection of the tongue and mucous membranes of the mouth.
172
What does thrush consist of?
friable, white, curd-like membranes adherent to the affected area.
173
What does removal of the membrane involved in thrush?
leaves a painful bleeding surface.
174
What conditions may predispose to the reemergence of endogenous microorganisms?
immunosuppressive states such as cancer, chemotherapy, immunosuppressive therapy, AIDS, and old age.
175
What does secondary tuberculosis result from?
the proliferation of M. tuberculosis in a person who has been previously infected and has mounted an immunologic response.
176
What is the source of infection for secondary tuberculosis?
It is usually dormant bacteria from old granulomas but may also represent a newly acquired infection.
177
What are the most common sites of reinfection for secondary tuberculosis?
lung
178
What does the bacilli elicit?
an acute inflammatory response that leads to extensive tissue necrosis and the production of tuberculous cavities.
179
Clinically what do secondary tuberculosis patients present with?
cough, low-grade fever, malaise, fatigue, anorexia, weight loss, and night sweats
180
What does parainfluenza virus cause?
acute upper and lower respiratory tract infections particularly in young children.
181
What are the most common cause of laryngotracheobronchitis?
The RNA parainfluenza viruses referred to as “croup.”
182
What is laryngotracheobronchitis characterized by?
a subglottic swelling and airway obstruction, which lead to acute respiratory distress.
183
How does the parainfluenza virus spread?
The infection spreads from person to person through contaminated respiratory aerosols and secretions.
184
The parainfluenza virus does what to the cells?
infects and kills ciliated respiratory epithelial cells and elicits an inflammatory response.
185
What happens when laryngotracheitis occurs?
localized edema compresses the upper airway enough to obstruct breathing.
186
What are the symptoms associated with croup?
They include fever, hoarseness, barking cough, and inspiratory stridor.
187
Human parvovirus B19
is a DNA virus that causes systemic infections
188
What is human parvovirus B19 characterized by?
rash, arthralgias, and a transient defect in erythropoiesis.
189
How is human parvovirus B19 spread?
the virus is spread from person to person through respiratory secretions.
190
Infections by parvovirus B19 are common in?
children.
191
The parvovirus B19 is cytopathic for?
erythroid precursor cells in the bone marrow.
192
The nuclei of cells infected by parvovirus B19 are?
enlarged, and the chromatin is displaced to the periphery.
193
What do most parvovirus B19 patients suffer from?
a mild exanthema known as erythema infectiosum.
194
How does the parvovirus B19 relate to apalstic crisis?
in patients with chronic hemolytic anemia (e.g., sickle cell disease), this transient interruption in erythropoiesis causes a potentially fatal condition known as “aplastic crisis.”
195
Tosoplasmosis and the CNS?
Infection of the central nervous system produces a necrotizing meningoencephalitis, which, in the most severe cases, results in destruction of brain parenchyma, cerebral calcification, and hydrocephalus.
196
Toxoplasmosis
is a worldwide disease caused by the protozoan T. gondii.
197
Most toxoplasmosis infections are?
asymptomatic, but a devastating necrotizing disease may occur when they involve the fetus or an immunocompromised adult.
198
Toxoplasmosis and eye infections?
Ocular infections cause chorioretinitis.
199
Frequency of group B streptococci in neonates?
Several thousand neonatal infections with group B streptococci occur in the United States every year.
200
What proportion of the neonates affected by group B streptococci die?
About 30% of infected infants die.
201
Meningococci are
Gram-negative organisms.
202
Endemic typhus is
a severe vasculitis transmitted by R. typhi through the bite of infected lice.
203
What does the endemic typhus begin with?
localized infection of capillary endothelium, which progresses to systemic vasculitis.
204
For endemic typhus where are mononuclear cell infiltrates found?
in multiple organs and are typically arranged in typhus nodules.
205
Louse-borne typhus is characterized clinically by
fever, severe headache, and myalgias, followed by the appearance of a maculopapular rash on the upper trunk and axillary folds, spreading centrifugally to the extremities.
206
Chagas disease
is an insect-borne systemic infection in humans caused by the protozoan T. cruzi.(Trypanosoma cruzi)
207
For Chagas, where does acute manifestations and the long-term sequelae of infection occur primarily?
in the heart and gastrointestinal tract.
208
Where are chagas infections endemic in?
Central and South America,
209
In Central and South America how is Trypanosoma cruzi transmitted?
they are transmitted by the Reduviid (“kissing”) bug, which hides within the cracks and straw roofs of older homes.
210
How does Trypanosoma cruzi relate to myocarditis?
The parasite reproduces within the myocardium and causes myocarditis.
211
Fungus balls
(aspergillomas) consist of rounded, lobulated masses of hyphae
212
Aspergillosis occur in patients with what?
a previous history of cavitating pulmonary disease (e.g., pulmonary tuberculosis).
213
Aspergillus
is a common environmental fungus that causes opportunistic infections in the lungs.
214
What happens to inhaled Aspergillus spores?
they germinate in the warm humid atmosphere provided by cavitary lung lesions, filling them with masses of hyphae.
215
At what point in the infection does the aspergillus invade the lung parenchyma?
The organisms generally do not invade the lung parenchyma.
216
What are the there are three different types of pulmonary aspergillosis?
1) allergic bronchopulmonary aspergillosis, 2) aspergillomas, 3) invasive aspergillosis.
217
Candidiasis
Candida infections are not typically angioinvasive.
218
E. histolytica
Entamoeba histolytica, resides in the colon of infected persons and is transmitted by fecaloral contact.
219
How do the trophozoites of E. histolytica gain access to the liver?
They invade submucosal veins of the colon, enter the portal circulation, and gain access to the liver.
220
For E. histolytica, what does the amebae do to the hepatocytes?
kill hepatocytes, producing a slowly expanding, necrotic cavity.
221
Describe the abccess created by E. histolytica?
The abscess is filled with a dark brown material that resembles anchovy paste.
222
What can happen with an amebic liver abscess?
can rupture and extend into the peritoneal cavity.
223
Staphylococcus aureus food poisoning is caused by
the ingestion of food contaminated with preformed, heat-stable enterotoxin B.
224
Outbreaks of Staphylococcus aureus food poisoning occur when?
When food handlers inoculate foods such as meat or dairy products (salad dressings, cream sauces, and custard-filled pastries) with contaminated wounds or infected nasal droplets.
225
When does Staphylococcal food poisoning typically begin?
less than 6 hours after a meal.
226
When do symptoms for Staphylococcus aureus food poisoning usually resolve?
Nausea and vomiting usually resolve within 12 hours. The other choices do not initiate rapid gastrointestinal symptoms.
227
Mycobacterium avium-intracellulare. - M. avium and M. intracellulare
they are similar mycobacterial species that cause identical diseases
228
How are M. avium and M. intracellulare classified?
together as M. avium-intracellulare complex (MAC).
229
MAC in immunocompetent versus immunocomprimised individuals.
(M. avium and M. intracellulare) is a rare, granulomatous, pulmonary disease in immunocompetent persons, but it is a progressive systemic disorder in patients with AIDS.
230
What proportion of all AIDS patients develop overt MAC infections?
One third of all AIDS patients
231
In MAC (M. avium and M. intracellulare) what forms the lesions?
The proliferation of organisms and the recruitment of macrophages produce expanding lesions, ranging from epithelioid granulomas containing few organisms to loose aggregates with foamy macrophages.
232
What are the symptoms associated with MAC?
resemble those of tuberculosis; however, progressive involvement of the small bowel produces malabsorption and diarrhea.
233
Camplyobacter jejuni
produces a self-limited bacterial diarrhea.
234
Cryptosporidium
is a protozoan that causes diarrhea in immunocompromised patients but is not associated with respiratory infections.
235
Streptococcus pyogenes causing Impetigo
patient represents a localized, intraepidermal infection with S. pyogenes.
236
How does impetigo from S pyogenes spread?
by close contact and most commonly affects children.
237
What is the relatioinship between S pyogenes resulting in impetigo and minor trauma?
It allows inoculation of the bacteria, forming an intraepithelial pustule that eventually ruptures and leaks a purulent exudate.
238
S. pneumoniae is a major cause of what?
lobar pneumonia, otitis media, sinusitis and meningitis.
239
S. viridans
is a major cause of bacterial endocarditis.
240
Treponema pallidum
produces a maculopapular rash of the palms and soles in secondary syphilis.
241
Staphylococcus aureus. S. aureus is a
Gram-positive coccus
242
What is the most common cause of suppurative infections involving the skin, joints, and bones?
S. aureus
243
What is one of the most common causes of acute bacterial endocarditis?
S. aureus
244
How does S. aureus relate to the heart?
this infection features colonization of heart valves or mural endocardium, leading to the formation of friable vegetations composed of thrombotic debris and microorganisms.
245
Bacterial growth in the heart is often associated with what?
Destruction of the underlying valve tissue.
246
What is one of the most common complications of IV drug abuse involving the heart?
Tricuspid insufficiency secondary to bacterial endocarditis
247
For bacterial endocarditis in IV drug users what is the most common source for the bacteria?
in these patients the most common area is the skin.
248
What proportion of bacterial endocarditis in IV drug users involves the tricuspid valve?
it is infected in half of the cases.
249
Nontyphoidal species of Salmonella contaminate what?
a variety of foods, including poultry, eggs, meat, and dairy products.
250
Salmonella infections are characterized clinically by?
diarrhea, which begins 12 to 24 hours after ingestion of the contaminated food.
251
Salmonella food poisoning
it is self-limited, lasting from 1 to 3 days.
252
What happens to Salmonella in the GI?
1) The bacteria proliferate in the small intestine and invade enterocytes, where they produce several toxins that contribute to the dysfunction of the intestinal epithelium. 2) The mucosal surface of the ileum and colon become acutely inflamed and occasio
253
Does pathogenic Escherichia coli infect eggs?
does not typically infect eggs.
254
Staphylococcus aureus characteristically causes what?
diarrhea 1 to 6 hours after ingestion.
255
Granuloma inguinale
is a sexually transmitted, chronic, superficial ulceration of the genital, inguinal, and perianal region.
256
What is Granuloma inguinale caused by?
Calymmatobacterium granulomatis, a small Gram-negative bacillus.
257
What is the characteristic lesion for Granuloma inguinale?
is a beefy-red superficial ulcer.
258
What is seen with Granuloma inguinale microscopically?
the dermis and subcutis are infiltrated by macrophages and plasma cells.
259
What are seen in Granuloma inguinale Skin lesions?
show microorganisms, termed “Donovan bodies,” clustered within enlarged macrophages.
260
Trichinosis is produced by what?
the roundworm Trichinella spiralis.
261
After mating, the females for Trichinella spiralis do what?
they liberate larvae into the circulation.
262
What happens to the larvae for Trichinella spiralis?
they can invade almost any tissue but survive only in skeletal muscle in an encapsulated form.
263
Elevated serum levels of creatine kinase indicate
muscle cell necrosis.
264
For Trichinella spiralis, Early muscle involvement elicits what?
an intense inflammatory infiltrate rich in eosinophils.
265
Mycobacterium leprae.
Leprosy (Hansen disease) is caused by M. leprae and appears in two forms, namely tuberculoid and lepromatous.
266
The tuberculoid type
occurs in patients who mount an immunologic response,
267
The lepromatous form
are anergic.
268
Lepromatous leprosy is
a chronic, slowly progressive, destructive process involving peripheral nerves, skin, and mucous membranes.
269
Patients with lepromatous leprosy exhibit what?
multiple nodular lesions of the skin, eyes, testes, nerves, lymph nodes, and spleen. The skin infiltrates expand slowly to distort and disfigure the face, ears, and upper airways. There is also involvement of the eyes, eyebrows, eyelashes, nerves, and tes
270
Cat-scratch disease is
(Bartonella henselae) a self-limited infection caused by B. henselae or (more rarely) B. quintana.
271
These bacteria (B. henselae, B. quintana) are
small, Gram-negative rods that are difficult to culture but easily seen in a lymph node biopsy when stained with silver.
272
How would you identify B. henselae, B. quintana?
They are difficult to culture but easily seen in a lymph node biopsy when stained with silver.
273
Where does B. henselae multiply?
in the walls of small vessels and extracellular collagen fibers at the site of inoculation.
274
To where are the organisms B. henselae, B. quintana carried?
to the lymph nodes, where they produce suppurative lymphadenitis.
275
Pasteurella multocida
is associated with wound infection after animal bites.
276
What happens to the lymph nodes in B. henselae, B. quintana?
they enlarge and drain through the skin.
277
About half of B. henselae, B. quintana infected patients present with what?
systemic symptoms such as fever, malaise, rash, and erythema nodosum.
278
Eikenella corrodens
produces wound infections after human bites.
279
Hookworm
(Ancylostoma duodenale). Hookworms are intestinal nematodes that infect the small bowel.
280
A. duodenale does what in the GI?
molts within the duodenum and attaches to the mucosa.
281
What might happen with extensive infections of Ancylostoma duodenale?
particularly with A. duodenale, considerable blood loss results in iron-deficiency anemia.
282
What does VZV initially infect?
Varicella-zoster virus initially infects cells of the respiratory tract or conjunctival epithelium
283
What does VZV do after it initially infects the cells of the respiratory tract or the conjunctival epithelium?
then reproduces and spreads via the bloodstream and lymphatic system.
284
What does first exposure to the VZV produce?
chickenpox,
285
What is chickenpox?
an acute systemic illness whose dominant feature is a generalized vesicular skin eruption.
286
Reactivation of latent VZV in adults causes what?
herpes zoster.
287
Microscopically what is seen with VZV?
intraepithelial vesicles contain multinucleated giant cells and nuclear inclusions.
288
Human herpesvirus-8
is associated with Kaposi sarcoma in patients with AIDS.
289
Herpes simplex virus type 2.
Herpes simplex viruses are common human pathogens,
290
What does herpes simplex virus most frequently produce?
recurrent painful vesicular eruptions of the skin and mucous membranes.
291
Calymmatobacterium granulomatis
is associated with a painful genital ulcer (chancroid).
292
Human papillomavirus relates to
genital warts.
293
Treponema pallidum
causes syphilis.
294
Where does the latent form of herpes virus survive?
In the sacral ganglia
295
Herpesvirus ascends from
genital lesions along sensory neurons and survives in a latent form in the sacral ganglia.
296
Nonspecific stimuli (including sexual intercourse and menses) can do what to the herpes virus?
Reactivate the virus, which then descends along axons to the genital mucosa, causing recurrent blisters on the external and internal genitalia.
297
Enterobius vermicularis
causes enterobiasis (“pinworm”) is an intestinal nematode
298
Where is Enterobius vermicularis found?
is encountered worldwide but is more common in temperate zones.
299
Who does Enterobius vermicularis affect?
Individuals can be infected at any age, but parasitism is more common in children.
300
With Enterobius vermicularis what do most people complain of?
pruritus
301
In Enterobius vermicularis infection what is pruitus caused by?
migrating worms.
302
What are Ancylostoma duodenale and Necator americanus? They are associated with?
They are hookworms associated with intestinal bleeding and iron-deficiency anemia.
303
Schistosomiasis is caused by?
Schistosoma haematobium.
304
What is the most important helminthic disease of humans?
Schistosomiasis
305
What is Schistosomiasis characterized by?
intense inflammatory and immunologic responses that damage the liver, intestine, and urinary bladder.
306
S. haematobium causes
urogenital infections and increases the risk for developing squamous cell carcinoma of the bladder.
307
S. mansoni affects what?
the liver.
308
Erysipelas
is an erythematous swelling of the skin caused chiefly by Streptococcus. Pyogenes infection.
309
S. pyogenes, also known as
group A streptococcus,
310
Is Streptococcus. pyogenes common?
it is one of the most frequent bacterial pathogens of humans
311
What does Streptococcus. pyogenes produce?
various diseases ranging from acute self-limited pharyngitis to rheumatic fever. The rash usually begins on the face but can affect any part of the body.
312
What is common in Streptococcus. pyogenes resulting in erysipelas?
Cutaneous microabscesses and foci of necrosis are common.
313
Mycoplasma. Pneumonia
produces an acute self-limited lower respiratory tract infection, primarily in children and young adults.
314
In whom do most infections of mycoplasma pneumonia occur?
in groups of persons living in close contact.
315
What is walking pneumonia?
M. pneumoniae tends to be milder than other bacterial pneumonias
316
What is usually seen with M. pneumoniae?
Fever usually persists for no more than 2 weeks, although a cough may linger for 6 weeks or more.
317
For M. pneumoniae what is commonly seen on chest X-ray?
shows patchy consolidation of a single segment of a lower lung lobe.
318
M. pneumoniae is responsible for what proportion of all pneumonias in developed countries?
about 20%
319
Cryptococcus neoformans.
Cryptococcosis is a mycosis that primarily affects the meninges and lungs.
320
How is C. neoformans unique?
Its unique among pathogenic fungi because it has a proteoglycan capsule, which is essential for pathogenicity.
321
What is the main reservoir for C neoformans?
Main reservoir for this fungus is pigeon droppings.
322
What does Cryptococcus neoformans appear as?
faintly stained, basophilic yeast with a clear, 3- to 5-μm thick mucinous capsule.
323
Cryptococcus almost exclusively affects persons with what?
impaired cell-mediated immunity.
324
For the following which stain with mucicarmine; Aspergillus flavus, Candida albicans, Coccidioides immitis, Cryptococcus neoformans, Histoplasma capsulatum ?
Cryptococcus neoformans
325
Yellow fever is
an acute hemorrhagic fever, which is associated with hepatic necrosis and jaundice.
326
What is yellow fever caused by?
a mosquito-borne flavivirus.
327
How is yellow fever related to shock?
extensive injury to vascular endothelial cells may cause hemorrhage and shock.
328
The flavivirus causing yellow fever has a tropism for?
liver cells, where it causes extensive hepatocellular injury.
329
What is seen in the liver as a result of exposure to flavivirus causing yellow fever?
Councilman bodies (apoptotic bodies) and microvesicular fatty change are evident.
330
What happens in severe cases of yellow fever?
the entire liver lobule may become necrotic.
331
For Leishmaniasis what are Leishmaniae?
Protozoans
332
How are Leishmaniae transmitted?
that are transmitted to humans through insect bites.
333
What is the spectrum of clinical syndromes cuased by Leishmaniae?
ranging from indolent self-resolving cutaneous ulcers to fatal disseminated disease.
334
Leishmaniasis is transmitted by
the bite of phlebotomus sandflies, which acquire infections from feeding on infected animals.
335
The infestation by Leishmaniae is primarily a disease of what population?
less developed countries, where over 20 million people are believed to be infected.
336
What are the three distinct clinical entities for Leishmaniae?
(1) localized cutaneous leishmaniasis, (2) mucocutaneous leishmaniasis, and (3) visceral leishmaniasis.
337
What do patients with visceral leishmaniasis suffer from?
persistent fever, progressive weight loss, hepatosplenomegaly, anemia, thrombocytopenia, and leukopenia. Light-skinned persons develop darkening of the skin.
338
What happens if Leishmaniae is untreated?
the disease is fatal.
339
Giardia lamblia – Giardiasis
is an infestation of the small intestine by the flagellated protozoan G. lamblia.
340
How might Giardia lamblia be acquired?
from contaminated water or food
341
What are the Giardia lamblia infection characterized by?
abdominal cramping and nonbloody diarrhea.
342
When are the gastrointestinal symptoms for Giardia lamblia usually resolved?
in 1 to 4 weeks
343
In Giardia lamblia, what might chronic giardiasis lead to?
malabsorption, weight loss, and growth retardation.
344
In Giardia lamblia, form where are the organisms recovered?
from stool specimens, duodenal aspirates, or intestinal biopsies.
345
Rhinovirus.
The common cold is an acute, self-limited disorder of the upper respiratory tract caused by infection with a variety of RNA viruses, including over 100 distinct rhinoviruses and several coronaviruses.
346
What do rhinoviruses infect?
the nasal respiratory epithelial cells, causing edema and increased mucus production.
347
Clinically, what is the common cold characterized by?
rhinorrhea, pharyngitis, cough, and lowgrade fever. Symptoms last about a week.
348
Human Parvovirus B19 infections are characterized by?
rash, arthralgias, and transient interruption in erythropoiesis.
349
HIV
is a lentivirus
350
Human Parvovirus B19 - Human parvovirus B19 is
a DNA virus that causes systemic
351
The Human Parvovirus B19 produces?
characteristic cytopathic effects in erythroid precursor cells.
352
What happens to the cells infected with Human Parvovirus B19?
The nucleus of an affected cell is enlarged, and the chromatin is displaced peripherally by central, glassy, eosinophilic material.
353
When the fetus is infected with parvovirus B19 what happens?
a transient cessation of erythrocyte production leads to severe anemia, hydrops fetalis, and often death in utero.
354
hydrops fetalis is
is the most serious form of erythroblastosis fetalis (Fig. 6-43) in liveborn infants. It is characterized by severe edema due to congestive heart failure caused by severe anemia. Affected infants generally die unless adequate exchange transfusions with R
355
TORCH syndrome
refers to a complex of similar signs and symptoms produced by fetal or neonatal infection with Toxoplasma (T), rubella (R), cytomegalovirus (C) and herpes simplex virus (H). In the acronym TORCH, the letter “O” represents “others”
356
Campylobacter jejuni.
C. jejuni (Campylobacter enteritis) causes an acute, self-limited, infl ammatory diarrheal illness.
357
Where is C. jejuni and how is it acquired?
The organism is distributed worldwide and is acquired through contaminated food or water.
358
What does C. jejuni cause in children? In adults?
It is a major cause of childhood mortality in developing countries and is responsible for many cases of travelers’ diarrhea.
359
C. jejuni causes what?
1) a superficial enterocolitis primarily involving the terminal ileum and colon. 2) Focal necrosis of the intestinal epithelium is accompanied by an acute inflammatory infiltrate.
360
What happens in severe cases of C. Jejuni?
focal disease progresses to small ulcers and patchy inflamatory exudates (pseudomembranes).
361
When do the symptoms for C. jejuni typically resolve?
in 5 to 7 days.
362
What happens to a few C. jejuni patients?
they develop a severe, protracted illness resembling acute ulcerative colitis.
363
Clostridium perfringens.
Gas gangrene (clostridial myonecrosis)
364
Clostridium perfringens
(clostridial myonecrosis) is a necrotizing, gas-forming infection that begins in contaminated wounds and spreads rapidly to adjacent tissues.
365
Can clostridial myonecrosis be fatal?
The disease can be fatal within hours of onset.
366
Gas gangrene follows what?
the deposition of C. perfringens into tissues under anaerobic conditions.
367
What are the conditions that allow for the deposition of C perfringens?
they occur in areas of extensive necrosis (e.g., severe trauma, wartime injuries, and septic abortions).
368
Clostridial myonecrosis is rare when
the wound is subjected to prompt and thorough debridement of dead tissue.
369
Damage to previously healthy muscle is mediated by a
myotoxin.
370
C. botulinum
secretes a preformed neurotoxin.
371
Cysticercosis.
1) Pigs acquire cysticerci by ingesting eggs of Taenia solium shed in human feces. 2) When humans accidentally ingest the eggs from human feces and become infected with cysticerci, the consequences may be catastrophic.
372
What do the eggs from human feces of Taenia slium release?
Oncospheres
373
What happens to the oncospheres from the eggs of Taenia silum from human feces?
It penetrates the wall of the gut, enter the bloodstream, lodge in tissues, and differentiate to cysticerci.
374
What is the cysticercus?
it is a spherical milky white cyst of about 1 cm in diameter that contains fluid and an invaginated scolex (head of the worm). Viable cysts can be shelled out from the infected tissue.
375
Multiple cysticerci in the brain
may impart a “Swiss cheese” appearance and manifest clinically as headaches and seizures.
376
Which of the following infect the brain: Aspergillosis, Clonorchiasis, Cysticercosis, Fascioliasis Paragonimiasis?
Cysticercosis
377
Is Aspergillosis of the brain common?
it is distinctly uncommon.
378
What is the most common lethal autosomal recessive disorder in the white population?
Cystic fibrosis
379
What is cystic fibrosis characterized by?
(1) chronic pulmonary disease, (2) deficient exocrine pancreatic function (3) other complications of inspissated mucus in a number of organs, including the small intestine, the liver, and the reproductive tract.
380
What does cystic fibrosis result from?
abnormal electrolyte transport caused by impaired function of the chloride channel of epithelial cells.
381
What are the pulmonary symptoms of CF?
they begin with cough, which eventually becomes productive of large amounts of tenacious and purulent sputum.
382
What happens in the progression of CF?
Episodes of infectious bronchitis and bronchopneumonia become progressively more frequent, and eventually shortness of breath develops.
383
What happens late in CF?
Respiratory failure and the cardiac complications of pulmonary hypertension (cor pulmonale) are late sequelae.
384
What are the most common organisms that infect the respiratory tract in CF?
Staphylococcus and Pseudomonas species.
385
As CF advances, what organism might be the only one cultured from the lung?
Pseudomonas where the recovery of Pseudomonas sp., particularly the mucoid variety, from the lungs of a child with chronic pulmonary disease is virtually diagnostic of CF.
