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Path Bac > Chapter 24 > Flashcards

Chapter 24 Flashcards

1
Q

The four most important genera in the family Pasteurellaceae are…

A

Haemophilus, Actinobacillus, Aggregatibacter, and Pasteurella

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2
Q

Members of this genus (in Pasteurellaceae) are the most significant human pathogens.

A

Haemophilus

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3
Q

Haemophilae are small, sometimes ________, gram-negative bacilli present on ________.

A

pleomorphic (=variability in size and shape)

mucous membranes of humans

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4
Q

Which Haemophilus species is most commonly associated with disease?

A

Haemophilus influenzae

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5
Q

Haemophilus influenzae is primarily associated with infections in ________.

A

children

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6
Q

The introduction of the ________ has dramatically reduced the incidence of H. influenzae disease, particularly in the pediatric population.

A

Haemophilus influenzae type b vaccine (Hib)

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7
Q

Which Haemophilus species is commonly isolated but rarely associated with disease?

A

Haemophilus parainfluenzae

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8
Q

What kind of pathogen is Haemophilus parainfluenzae?

A

opportunistic pathogen

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9
Q

Which Haemophilus species is associated with acute, purulent conjunctivitis (pink eye)?

A

Haemophilus aegyptius

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10
Q

What is the etiologic agent of Brazilian Purpuric Fever?

A

H. influenzae Biogroup aegyptius – responsible for 70% mortality rate among children during outbreak in several small Brazilian towns between 1984 through 1986.

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11
Q

What is the etiologic agent of chancroid?

A

Haemophilus ducreyi

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12
Q

Most Haemophilus species require supplemented media, such as chocolate agar, which contains…

A

Hemin (X factor)

NAD (V factor)

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13
Q

Describe the cell wall structure of Haemophilus.

A

The cell wall structure of Haemophilus is typical of other gram-negative rods (bacilli). Lipopolysaccharide (LPS) with endotoxin activity is present in the cell wall, and strain-specific and species-specific proteins are found in the outer membrane.

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14
Q

The surface of many, but not all, strains of H. influenzae is covered with… How many capsular antigenic serotypes have been identified?

A

An LPS capsule

Six capsular antigenic serotypes: a-f

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15
Q

Before Hib vaccine, which serotype was responsible for 95% of all invasive H. influenzae infections? After the Hib vaccine, what is responsible for most H. influenzae disease?

A

H. influenzae serotype b

H. influenzae serotypes c and f, along with non-encapsulated (non-typeable) H. influenzae

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16
Q

What percentage of H. influenzae disease is caused by non-typeable strains?

A

Greater than 50% of disease caused by non-typeable strains.

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17
Q

H. influenzae serotypes are further subdivided into ________ biotypes. For what purpose?

A

H. influenzae serotypes further subdivided into eight biotypes – useful for epidemiologic purposes.

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18
Q

Which H. influenzae serotype is the most important/virulent? – remains a significant pediatric pathogen in many parts of the world.

A

H. influenzae serotype b

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19
Q

H. influenzae biotypes I-VIII are determined by which biochemical reactions?

A

Indole production, urease activity, and ornithine decarboxylase activity.

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20
Q

H. influenzae biogroups are distinguished on the basis of what? Which biogroup is the most important?

A

Biogroups, distinguished on basis of nature of disease, growth properties, outer membrane protein profile. H. influenzae biogroup aegyptius most important.

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21
Q

Which Haemophilae colonize the URT within the first few months of life? These organisms can spread locally and cause disease where? Is disseminated disease common?

A

H. parainfluenzae and non-encapsulated strains of H. influenzae colonize URT within first few months of life. These organisms can spread locally and cause disease in the ears (otitis media), sinuses (sinusitis), and lower respiratory tract (bronchitis, pneumonia). Disseminated disease, however, is relatively uncommon.

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22
Q

Is H. influenzae influenzae type b common or uncommon in the URT? It is a common cause of invasive disease in whom?

A

It is uncommon in the URT, but is a common cause of disease in unvaccinated children (i.e., meningitis, epiglottitis, cellulitis).

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23
Q

With H. influenzae, adhesions mediate what? The LPS impairs what?

A

Adhesions mediate colonization of the oropharynx. The LPS impairs ciliary function, leading to damage of the respiratory epithelium.

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24
Q

Can H. influenzae enter the blood? How? This can lead to what?

A

After colonization of the oropharynx and respiratory epithelum damage, the bacteria can then be translocated (=move from one place to another) across both epithelial and endothelial cells and can enter the blood. In the absence of specific opsonic antibodies directed against the polysaccharide capsule, high-grade bacteremia can develop, with dissemination to the meninges or other distal foci.

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25
Q

The major virulence factor in H. influenzae type b is what? Antibodies directed against the capsule develop because of…?

A

The major virulence factor is the antiphagocytic polysaccharide capsule. Antibodies against capsule can develop as result of: natural infection, vaccination, and passive transfer of maternal antibodies.

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26
Q

Haemophilus species are present in whom? Where?

A

Haemophilus species are present in most humans, primarily as colonizer of mucosal surfaces of respiratory tract.

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27
Q

Which Haemophilus species constitutes 10% of flora in saliva?

A

H. parainfluenzae constitutes 10% of flora in saliva.

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28
Q

Which H. influenzae serotype is the most common cause of systemic disease?

A

H. influenzae type b is the most common serotype causing systemic disease.

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29
Q

Before the introduction of what, 20,000 cases of H. influenzae type b disease/year in U.S. children under five?

A

Before the introduction of conjugated vaccine.

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30
Q

The first vaccine (1977) against polysaccharide antigens was not effective in whom? In 1987, conjugated vaccines containing purified PRP bound to protein carries found to elicit protective antibody response in children as young as…?

A

Not effective in children <18 months. As young as 2 months.

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31
Q

Since licensure of conjugate vaccines for infants (1990) and children (1987), rates of Hib disease among children younger than 5 years old have ________. Rates for adults in U.S. have ________. Rates of disease among ________ remain higher than elsewhere in the U.S.

A

declined by 99% in the U.S. Rates for U.S. adults have remained stable. Alaska Natives.

32
Q

What currently causes the majority of invasive H. influenzae disease among ALL age groups in the U.S.?

A

Non-typeable (non-encapsulated) H. influenzae

33
Q

From 2009-2014, the annual incidence of invasive nontypeable H. influenzae disease was in whom?

A

In children < 5 years of age and adults > 65 years of age

34
Q

Nontypeable H. influenzae also causes 30-52% of episodes of ________ and ________ in whom?

A

Nontypeable H. influezae also causes 30-52% of episodes of acute otitis media and sinusitis in children.

35
Q

What is a common cause of recurrent otitis media?

A

Nontypeable H. influenzae

36
Q

H. influenzae type b remains the most significant pediatric pathogen where? In whom?

A

H. influenzae type b remains most significant pediatric pathogen in many countries where routine vaccination still not implemented. Significant concern in adults with waning immunity.

37
Q

________ and ________ infections caused by these organisms are primarily pediatric diseases but can occur in adults. Pulmonary disease most commonly affects ________, particularly those with a history of underlying ________ or conditions predisposing to ________ (e.g., alcoholism, altered mental state).

A

Ear and sinus infections caused by these organisms are primarily pediatric diseases but can occur in adults. Pulmonary disease most commonly affects elderly people, particularly those with a history of underlying chronic obstructive pulmonary disease or conditions predisposing to aspiration (e.g., alcoholism, altered mental state).

38
Q

Epiglottitis is a disease characterized by what? The peak incidence of epiglottitis is in whom? Is epiglottitis common or uncommon in vaccinated populations?

A

Disease characterized by cellulitis and swelling of supraglottic tissue – life threatening condition, obstruction of airway. Peak incidence of disease 2-4 years of age. Rarely seen in vaccinated population.

39
Q

Since the introduction of Hib vaccine, the most common cause of epiglottitis in developed countries is now what?

A

Group A beta-hemolytic strep.

40
Q

Cellulitis is characterized by what? Diagnosis is suggested by what?

A

Cellulitis is characterized by development of reddish blue patches on cheeks and periorbital areas. The diagnosis is strongly suggested by the typical clinical presentation, cellulitis proximal (=close to) to the oral mucosa, and lack of documented vaccination history.

41
Q

H. influenzae is the most common cause of ________ in unvaccinated children under 2 years of age.

A

arthritis

42
Q

Otitis, sinusitis, and LRT disease are caused by ________. ________ and ________ are the two most common causes of acute and chronic otitis and sinusitis.

A

Caused by non-encapsulated strains of H. influenzae. H. influenzae and Strep pneumoniae are two most common causes of acute and chronic otitis and sinusitis.

43
Q

Conjunctivitis is caused by ________, also called ________. Is it contagious? It is associated with epidemics during ________.

A

Caused by H. aegyptius (Koch-Weeks bacillus). Contagious, associated with epidemics during warm months of the year.

44
Q

Meningitis in non-immune patients results from? Can H. influenzae meningitis be clinically differentiated from other bacterial meningitis?

A

Disease in non-immune patients results from spread of organism from nasopharynx. It cannot be clinically differentiated from other bacterial meningitis.

45
Q

The initial presentation of H. influenzae meningitis is what? Mortality is less than 10% in whom? Person-to-person spread is common in whom? 3-6% of cases are ________. Up to 20% of surviving patients have ________.

A

The initial presentation is a 1- to 3-day history of mild upper respiratory disease, after which the typical signs and symptoms of meningitis appear. Mortality is less than 10% in treated patients. Person to person spread is common in non-immune populations. 3-6% of cases are fatal; up to 20% of surviving patients have permanent hearing loss or other long-term sequelae.

46
Q

Brazilian Purpuric Fever is caused by…?

A

Caused by H. influenzae biogroup aegyptius

47
Q

Brazilian Purpuric Fever is a life-threatening pediatric infection, preceded by what? In other words, illness begins with what? Then what? What do the other symptoms resemble? If untreated, what can develop?

A

Preceded by conjunctivitis caused by H. influenzae biogroup aegyptius. Illness beings with severe, pustular conjunctivitis – high fever, vomiting, abdominal pain and a purpuric rash. Other symptoms resemble those of infection with meningococcus. Untreated, life-threatening septicemia can develop.

48
Q

Chancroid is caused by what? Is it an STD? It is most commonly diagnosed in whom? Why?

A

Caused by H. ducreyi. It is an STD, most commonly diagnosed in men – women tend to have asymptomatic disease.

49
Q

With Chancroid, _______ develops on ________ or ________ area _______ days post exposure. What happens 2 days later? What is commonly present? What must be excluded before diagnosis of Chancroid is considered?

A

Tender papule develops on genitalia or perianal area 5-7 days post exposure. Lesions ulcerate and becomes painful 2 days later. Inguinal lymphadenopathy (=refers to nodes that are abnormal in size) commonly present. Syphilis and HSV must be excluded before diagnosis of Chancroid considered.

50
Q

Which Haemophilus species is an important cause of genital ulcers in Africa and Asia? It is less common where? The incidence in U.S. appears to be what? The incidence may be underreported – why?

A

Haemophilus ducreyi important cause of genital ulcers in Africa and Asia. It is less common in Europe and North America – incidence in U.S. appears to be cyclic. Incidence may be underreported – lesions resemble those of herpes or syphilus.

51
Q

________ from untreated patient is an excellent sample for diagnosis of Haemophilus meningitis. The organism is readily seen on ________ and easily recovered from ________.

A

CSF from untreated patient is an excellent sample of diagnosis of Haemophilus meningitis. Organism readily seen on gram stain and easily recovered from culture.

52
Q

Blood cultures are useful for the diagnosis of what?

A

Blood cultures are useful for the diagnosis of epiglottitis, cellulitis, arthritis, pneumonia.

53
Q

Direct needle aspirates are used for the diagnosis of ________. Specimens of diagnosis of H. ducreyi are collected with?

A

Direct needle aspirates (=matter that has been drawn from the body by suction) used for diagnosis of sinusitis or otitis. Specimens for diagnosis of H. ducreyi collected with moistened swab from base or margins of ulcer.

54
Q

Is microscopy sensitive and specific in detecting Haemophilus? What can be seen on the slide?

A

Microscopy is both sensitive and specific. Gram-negative pleomorphic rods – coccobacillus to long filaments.

55
Q

H. influenzae cultures are ________, ________ after 24 hours and easily isolated using ________ agar containing ________. The media must be what to confirm that the growth factors are present. H. influenzae can also be seen on blood agar under what condition? Where do the growth factors in blood agar come from?

A

Colonies are smooth, opaque after 24 hours and easily isolated using chocolate agar containing X and V factor. Media must be QC’d to confim X and V growth factors are present. Also seen on blood agar with straph sreak – staph lyses RBC’s releasting heme (X factor); staph also secrete NAD (V factor).

56
Q

________ requires both X and V factors for growth. ________ requires V factor only for growth.

A

H. influenzae; H. parainfluenzae

57
Q

H. influenzae growth in blood cultures is often delayed. Why? Under what condition can H. influenzae grow without X factor?

A

Growth in blood cultures often delayed – blood cultures bottles generally lack supplements. May grow better in anaerobic environment where organism can grow without X factor.

58
Q

H. aegyptius and H. ducreyi are more ________. What does H. aegyptius culture require? What does H. ducreyi culture require?

A

H. aegyptius – specialized media in increased CO2 for 2-4 days.
H. ducreyi – incubate at 33C, 5-10% CO2, >7 days. Must be looking for H. ducreyi in order to have chance of isolating from culture.

59
Q

What is a rapid, sensitive way to diagnose H. influenzae type b disease? Antigen can be detected in what? Is there a downside?

A

Antigen detection – rapid sensitive way to diagnose H. influenzae type b disease, specifically using latex agglutination. Antigen can be detected in CSF or urine, but limited to detecting only HIB, which is now uncommon in the U.S.

60
Q

Organism ID can be made by…

A

Requirement for X and/or V factor; specific biochemical properties; subgrouping of H. influenzae can be done with biotyping.

61
Q

Prompt antibiotic therapy required for ________ H. influenzae infections with ________. H. ducreyi drug of choice is ________, because many strains now resistant to ________.

A

Prompt antibiotic therapy required for SYSTEMIC H. influenzae infections with broad-spectrum anitbiotics. H. ducreyi drug of choice is Erythromycin, because many strains now resistant to Penicillins.

62
Q

Vaccination succesful in reducing incidence of ________ infection and colonization. How many vaccine doses during the first 6 months of life? What treatment is done for contacts of known systemic disease patients (daycare centers, family contacts, etc.)? ________ currently prophylactic drug of choice.

A

Vaccination successful in reducing incidence of H. influenzae type b infection and colonization. Three doses of Hib vaccine during first six months of life. Antibiotic prophylaxis for contacts of know systemic disease patients. Rifampin currently prophylactic drug of choice.

63
Q

In the U.S., Hib disease occurs primarily in whom?

A

In the U.S., Hib disease occurs primarily in under-immunized children and among infants too young to have completed the primary immunization series.

64
Q

In developing countries, where routine vaccaination with Hib vaccine is not widely available, Hib remains a major cause of ________ in infants and children.

A

lower respiratory tract infections

65
Q

The most virulent H. influenzae strain is ________, with its ________.

A

The most virulent strains is H. influenzae type b (Hib), with its polyribosyl ribitol phosphate (PRP) capsule.

66
Q

H. influenzae type b accounts for more than 95% of INVASIVE diseases in children and 1/2 of INVASIVE diseases in adults, including…

A

Bacteremia, meningitis, cellulitis, epiglottitis, septic arthritis, pneumonia, and empyema (=pus gathers in the area between the lungs and the inner surface of the chest wall)

67
Q

Less-common invasive Hib infections include…

A

Endophthalmitis, urinary tract infection, abscesses, cervical adenitis, glossitis, osteomylitis, and endocarditis.

68
Q

The nonencapsulated strains of H. influenzae cause…

A

Mucosal infections, including otitis media, conjunctivitis, sinusitis, bronchitis, and pneumonia.

69
Q

The two species in the genus Aggregatibacter are…?

A

A. actinomycetemcomitans and A. aphrophilus

70
Q

Both Aggregatibacter species colonize the human ________ and can spread into ________. They can stick to ________ or ________ and lead to endocarditis, which is difficult to diagnose – why? What is the treatment of choice?

A

Both species colonize the human mouth and can spread into blood stream – can stick to damanged heart valves or prosthetic valve and lead to endocarditis. Endocarditis caused by these bacteria difficult to diagnose – clinical signs and symptoms develop slowly (SBE); bacteria grow slowly in blood culture. Treatment of choice is a Cephalosporin (CTX).

71
Q

Actinobacillus are small facultative anaerobic, slow-growing, gram-negative rods – how slowly do they grow? A. actinomycetemcomitans was the most important human pathogen in this genus, but in 2006, this species moved to genus ________. The remaining members of this genus colonize the ________ of ________ and are rare causes of ________.

A

2-3 days for growth; Aggregatibacter; the remaining members of this genus colonize the oropharynx of animals and humans and are rare causes of peridontitis, endocarditis, bite wound infections, and opportunistic infections.

72
Q

Pasteurella are small facultative anaerobic, fermentative, gram negative ________. And is a common commensal in the oropharynx of ________. Most human infections result from ________.

A

coccobacilli; common commensal in the oropharynx of healthy animals; animal bites, scratches, shared food.

73
Q

Which Pasteurella species is the most common isolate? What is it associated with? Is P. canis a human pathogen? Are other Pasteurella species associated with human infection?

A

Pasteurella multocida most common isolate – associated with cat or dog bites or scratches; P. canis also a human pathogen; other species rarely associated with human infection.

74
Q

What are the three forms of Pasteurella disease reported?

A

Localized cellulitis and lymphadenitis associated with bite or scratch.
Exacerbation of chronic respiratory disease – associated with aspiration of oral secreations in colonized patients.
System infections in immunocompromised patients.

75
Q

Pasteurella multocida grows well on ________, but grows poorly on media selective for ________. Describe P. multocida colonies. What is the drug of choice for P. multocida?

A

Grows well on chocolate or blood agar, but grows poorly on media selective for gram-negative rods. Large buttery colonies with characteristic musty odor. Penicillin is drug of choice.

Path Bac (3 decks)

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