Bordetella, Brucella, Francisella Flashcards
(120 cards)
1
Q
Which species of Francisella is most implemented in human infections
A
F. tularensis
*causative agent of tularemia
2
Q
What are the four subspecies of Francisella?
A
- F.Tularensis subsp. tularensis (Type A) more virulent
- F.Tularensis subsp. holarctica (Type B)
- F.Tularensis subsp. mediasiatica
- F.Tularensis subsp. novicida (similar to Tularensis but less lethal)
3
Q
F. tularensis is transmitted by what?
A
-sheep, rabbits, ticks
4
Q
F. tularensis subsp. holarctica is transmitted by what?
A
-rodents and mosquitos
5
Q
Franscisella tularemia gram stain
A
-facultative intracellular pathogen
- target phagocytotic cells like macrophages
-strict aerobic gram-negative coccobacilli (poor staining)
6
Q
Fransciesella tularemia epidemiology
A
-widely distributed
- In the US cases are mostly concentrated in South Dakota, Arkansas, Missouri, Oklahoma
-Eastern and Northern Europe
7
Q
Casuative agent of tularemia
A
-rabbit fever
-deer fly fever
-lemming fever
-water rat trapper’s fever
8
Q
Tularemia is a zoonotic disease which comes from…
A
-rabbits
-rodents
-beavers
9
Q
Route of Infection for Francisella Tularemia
A
-Ingestion
-Inhalation
-Inoculation
10
Q
Route of Infection for Francisella Tularemia: Ingestion
A
-consumption of contaminated meat or water
11
Q
Route of Infection for Francisella Tularemia: Inhalation
A
-aerosolization
-handling infected carcasses (ex: skinning or dressing)
-mowing, brush hogging, landscaping
-Lab-acquired infection
12
Q
Route of Infection for Francisella Tularemia: Inncoluation
A
-Insect vectors
* biting flies
* ticks
* animals bites
13
Q
Clinical presentation of Francisella tularemia going into the bloodstream
A
-systemically ill
-high temps, chills, headache, malaise
-clinical manifestations range from mild and self-limiting to fatal
14
Q
Disease manifestations influenced by the route of inoculation for Fransciella tularemia
A
- Pneumonic
- Glandular
- Ulceroglandular
- Oropharyngeal
- Oculoglandular
- Typhoid (Systemic)
15
Q
Ulceroglandular
A
-most common clinical presentation (45-80% of cases)
-often a result of cutaneous (inoculation) injection
-ulceration at the primary site of infection with regional lymphadenopathy
-low fatality
16
Q
Glandular
A
-similar to ulceroglandular tularemia with regional lymphadenopathy but no ulcer formation
-may be a result of inoculation, inhalation, or ingestion
-low fatality
17
Q
Oculoglandular
A
-occurs when the bacteria enter through the eye (ex: when a person touches their eye during or following the butchering or dressing of infected animals)
-symptoms: irritation and inflammation of the eye and swelling of lymph glands in front of the ear
18
Q
Oropharyngeal
A
-infection is the result of eating or drinking contaminated food or water
-presents as sore throat, mouth ulcers, tonsilitis, and swelling of lymph glands in the neck
19
Q
Pneumonic
A
-this form results from inhalation of dust or aerosols containing the organisms
-it can also occur when other forms of tularemia are left untreated and bacteria spread through the bloodstream to the lungs
-this is the most serious form of tularemia
-symptoms: cough, chest pain, difficulty breathing
-HIGH FATALITY RATE
20
Q
Typhoidal
A
-this form is characterized by any combination of the general symptoms often acute illness with septicemia
-absence of ulceration or lymphadenopathy
-occurs following inhalation or dissemination of other forms of tularemia that are left untreated
-fatality rate 30-60%
21
Q
Diagnosis of Francisella tularemia
A
-specimens submitted for culture should be based on clinical presentation
-whole blood and serum is recommended specimen for all manifestations
22
Q
Growth characteristics of Francisella tularemia
A
-fastidious
-poor to no growth on sheep’s blood agar
-no growth on McConkey
- pinpoint growth on chocolate agar
-enhanced by cysteine-rich media (ex: Thioglycolate, Thayer Martin, and BCYE)
-takes 2-4 days to 2 weeks of growth
23
Q
Morphology of Francisella tularemia
A
-grey-white smooth raised colonies
-translucent or mucoid
24
Q
Francisella tularemia has negative biochemical results for
A
-oxidase, urease, satellite, or X and V factors
25
Francisella tularemia has weakly positive biochemical results for
-catalase, and B-lactamase activity
26
What diagnostic tool do we use to identify Francisella tularemia?
-the mainstay diagnostic tool is serology (including agglutination) and culture
-ID can be made using MALDI-TOF mass spec performed on cultural isolate
-presumptive ID can be made by DFA and immunohistologic staining with monoclonal antibody (no longer widely available)
-PCR can also be performed on infected tissue, blood, CSF, and other specimens at some labs not widely available
27
Francisella tularemia is what class agent
A
-suspected cases have to be worked up in a BSL-3 hood
28
What is the definition of a category A agent by the CDC?
-the US public health system and primary healthcare providers must be prepared to address various biological agents such as pathogens that are rarely seen in the US
1. can easily be disseminated or transmitted from person to person
2. result in high mortality rates and have the potential for major public health impact
3. might cause public panic and social disruption
4. require special action for public health preparedness
*Frnacisella is a CDC reportable organism (roughly 100 cases are documented each year)
29
What qualifies as a category A agent?
-low infectious dose (10-50 organisms)
- easily aerosolized
- high mortality rate
30
When to suspect Francisella
1. slow growth upon primary isolation (>48/72 hrs)
-gram stain colony: small gram neg coccobacilli
-work in the BSC until pathogen ruled out
-send to a reference lab for definitive ID
-BSL-3 precaution should be taken until ruled out (all work done in class II BSC hood, pates should be taped)
31
Francisella tularemia treatment
-standardized susceptibility testing is unavailable
-the organism is susceptible to
* aminoglycosides (streptomycin)
*gentamicin
* doxycycline
* chloramphenicol
* fluoroquinolones for severe cases
32
What is the most common species for human brucellosis?
1. B. melitensis
2. B. abortus
3. B. canis
4. B. suis
33
What is the most common isolate of brucellosis?
B. melitensis
34
Brucella spp. Morphology
-small gram-negative coccobacilli
-facultatively intracellular
-target phagocytotic cells such as macrophages
-nonmotile
-Aerobic (some prefer carbon dioxide for growth)
-may require supplementary CO2 on primary isolation
35
Infection with Brucella spp is defined as what?
-Brucellosis or Ungulant Fever
36
Where is the Brucella spp harbored?
-is a zoonotic disease, located in a variety of animals depending on the species of brucella
B.abortus: cattle
B.melitensis: sheep, goats
B. suis: swine
B. canis: dogs
37
What are the risk factors for Brucellosis?
-occupational: veterinarians, cattle ranchers, meat packing/slaughterhouse, lab personnel
-ingestion of unpasteurized raw dairy products
38
Route of ingestion for Brucella spp
1. Ingestion (of infected unpasteurized animal milk)
2. Inhalation (of aerosolized particles)
3. Direct contact with infected animal parts
4. Accidental inoculation of mucous membranes
39
The clinical presentation of Brucella spp. is divided into three stages...
1. Acute
2. Subchronic (undulant)
3. Chronic
40
Acute stage of Brucella spp.
-fever, malaise, headache, anorexia, myalgia and back pain
-within 1 to 4 weeks after exposure
41
Subchronic stage of Brucella spp.
-low temperature in the morning followed by rising temps in the afternoon and evening
-occur within 1 year after exposure
-arthritis and epididymoorchitis may occur
42
Chronic stage of Brucella spp.
-depression, arthritis, and chronic fatigue syndrome
- around 1 year after exposure
43
Pathology of Brucella spp.
-organism localizes in tissue rich in erythritol (ex: placenta tissue)
-organisms are ingested and replicated in neutrophils
-neutrophils are phagocytized by reticuloendothelial cells of the spleen, liver, and bone marrow
-untreated infections may cause granulomas in these organs
44
Diagnosis of Brucella spp.
-Brucella is a class B agent, definitive identification of cultural isolation is typically performed at public health labs like Wadsworth Center
-direct detection: conventional and real-time PCR methods are most reliable
-particle agglutination test on growth, with anti-smooth Brucella serum provides presumptive ID. Not done in routine lab
-serodiagnosis: classic antibody response, IgM followed by IgG. Detects antibodies for B. abortus, melitensis, and suis (NOT CANIS)
45
What class agent is Brucella spp.
B
46
What are the recommended specimens for the culture of Brucella spp.
-Blood: routine culture bottles are sufficient
* should be held 10-14 days but will grow within 5-7 days from the aerobic bottle (growth often within 2-4 days)
-Bone marrow, Lymph Nodes, and any other tissue may be cultured with limited success
*needs enriched agar
47
Culture requirements for Brucella spp.
1. Enriched agar (BBA- Brucella Blood Agar)
-contains horse or rabbit blood
-will grow more slowly on sheep blood agar
2. Incubation conditions
-requires increased CO2 (5-10%)
-the organism is a strict aerobe
3. Extended Incubation
- up to 3 weeks
48
Culture characteristics for Brucella spp.
-slow growing (2-3 days)
-smooth, raised, and translucent colonies
-exhibits growth on blood and chocolate agar
- brucella agar is recommended for specimens other than blood
-colonies are small, convex, smooth, translucent, nonheme, and slightly yellow after 48 hours of incubation
49
What biochemicals are Brucella spp positive for?
-oxidase, catalase, and urease (within 2 hrs)
50
Does Brucella spp, produce H2S?
Yes
51
Do Brucella spp. need X and V factor requirements?
No
52
What testing is preferred for Brucella spp?
-serologic testing is along with history and disease status to diagnose brucellosis
53
What is the CDC's definition of a category B agent?
1. are moderate to disseminate
2. result in moderate morbidity rates and low mortality rates
3. require specific enhancements of CDC diagnostic capacity and enhanced disease surveillance
54
Special considerations when working with Brucella spp.
-has a low infectious dose (100 organisms)
- easily aerosolized
-cultures/specimens should be handled at BSL-2 minimum but BSL-3 recommended
- all work should be done in a class II BSC until ruled out
-most frequently documented Lab acquired infection
55
Why is Brucella a frequently documented LAI?
-misidentified as Haemophilus, Moraxella, or Acinetobacter
-inhalation from the bench top manipulations
-accidental ingestion
56
When should you suspect Brucella spp.
-slow growth upon primary isolation (>48-72 hours)
-gram stain of colony: tiny gram-negative coccobacilli
*work in BSC until critical pathogen ruled out (Oxi +, no X or V factor, urea +)
-if you see those signs forward them to a reference lab for definitive ID
57
Treatment for Brucella spp.
-In vitro, susceptibility is not reliable
-prolonged treatment (6 weeks) with antibiotics that penetrate macrophages in order to prevent relapse
-initial therapy includes doxycycline or tetracycline in combination with streptomycin or rifampin
-surgical drainage may be required for localized infections
58
What is the major pathogen of the species Bordetella?
B pertussis and B parapertussis
59
What is the minor pathogen of the species Bordetella?
1. B bronchiseptica
2. B. avium
3. B. hinzii
4. B holmesii
5. B. petrii
6. B. trematum
60
Bordetella pertussis is the primary agent of which disease?
Whooping Cough
61
Bordetella pertussis is the common agent of which disease?
-whooping cough but presentation is much milder
62
Virulence factors identified in Bordetella pertussis
1. Adhesins
2. Pertussis toxin (PT)
3. Overcoming host defense
* B pertussis and B parapertussis share similar virulence control systems
*virulence factors help aid in adherence and colonization to the ciliated epithelium which contributes to much of its pathogenesis
63
Virulence factors identified in Bordetella pertussis: Adhesins
(ex: hemagglutinins)
-binds and paralyzes (renders ineffective) the ciliated epithelial cells. Cilia of the nasopharyngeal passages are no longer effective at keeping out the pathogen
64
Virulence factors identified in Bordetella pertussis: Pertussis toxin
-an exotoxin produced by the bacterium that allows the colonization of the respiratory tract and the establishment of the infection
65
Virulence factors identified in Bordetella pertussis: overcoming host defense
-outer membrane interferes with lysozyme production by the host. Produces siderophores (iron chelating compounds) which interfere with the host management of iron
66
What can the pertussis toxin do?
1. disrupt tight junctions
2. inhibit GPCR (G protein coupling receptor) to promote pulmonary hypertension
3. inhibits lymphocyte homing to lymph node and extravasation
4. inhibit phagocytosis
5. Induces chemokines and cytokines
6. Inhibits early neutrophil recruitment
7. reduces numbers and functions of Tregs (regulatory T cells)
8. Suppresses antibody responses
67
What are the three distinct stages of Whooping cough (Pertussis)
1. catarrhal phase
2. Paroxysmal phase
3. convalescent
68
What are the three distinct stages of Whooping cough (Pertussis): catarrhal phase
-1 to 2 weeks
-mild cold symptoms, nasal congestion, sneezing, low-grade fever
69
What are the three distinct stages of Whooping cough (Pertussis): Paroxysmal phase
- 1 to 2 weeks
-severe and violent coughing, paroxysms of intense coughing lasting up to several minutes, occasionally followed by a loud whoop
-post-tussive vomiting and turning red with coughing
70
What are the three distinct stages of Whooping cough (Pertussis): Convalescent
-1 to 2 weeks
- lymphocytosis and chronic cough which may last for weeks
71
How is Bordetella spp. transmitted?
-the bacteria are spread from person to person in airborne droplets
-90 % of exposure contacts get the disease
-by direct contact with an infected throat or nasal discharge
-coughing and sneezing are the most common modes of transmission
-adults can be transient carriers
72
What are some factors that affect B. pertussis infection?
1. Age
2. Previous immunization or infection
3. passively acquired antibody
4. antibiotic treatment
73
What is the trend of Bordetella spp. since the 1990s
-shift to adolescents and adults: vaccinated population
-waning vaccine-induced immunity
-serve as a reservoir for transmitting to vulnerable infants
74
Bordetella spp. in children
-can cause serious infections in young children
-cyanosis from lack of oxygen
-sometimes in need of keeping airways open
75
Bordetella spp. Infant mortality
-infants <12 months old have the highest rates of complications and deaths from pertussis of any age group
-91 infant deaths were reported between 1999-2004 with pertussis as a cause of death
-all infants were 7 months or younger, 58% were aged <2 months
76
Lab dignosistic of Pertussis: Culture
-limited sensitivity
77
Lab diagnostic of Pertussis: DFA- Direct fluorescent antibody stain
-limited sensitivity, must be accompanied by culture
78
Lab dignosistic of Pertussis: NAAT- Nucelc acid amplification testing
-target IS481 region
-as sensitive or more so than culture
-may not be as specific, other Bordetella sp. have the IS481
79
Lab dignosistic of Pertussis: RT-PCR
-IS481 and 283 regions
-as sensitive or more so than culture
-greater specificity for Bordetella pertussis
80
What is the optimal specimen type for the recovery of B.pertussis?
-nasopharyngeal swab
81
What media is needed to transport Bordetella pertussis?
-since bordetella pertussis is extremely susceptible to toxic substances and metabolites, it needs to be transported in a transport medium containing neutralizing agents like charcoal (Regan-Lowe transport) if culture is requested
82
Why is the timing of collection key to recovering or detecting organisms?
-culture is most sensitive in samples collected early in the disease (first 1-2 weeks)
-organisms may become undetectable by culture in samples collected >2 weeks from the start of the cough
-organisms detectable by molecular methods (PCR) up to 4 or more weeks from the start of the cough
83
How is Pertussis cultured?
-recovery is optimized by supplemented media
-such as Reagan-lowe media, bordet-Gengou, supplemented with glycerol, charcoal, horse blood, cephalexin
-prolonged incubation at 35 degrees in ambient air
84
What are the Bordetella spp, culture characteristics?
-growth around 3 days
-small, shiny, whiteish-grey colonies
-on Bordet-Gengou agar, B-hemolytic
-commonly described as mercury drops
-colonies are faintly staining coccobacilli
85
How can B.pertussis and B.parapertussis be distinguished from each other?
B. pertussis
oxidase: +
urease: -
growth rate: + (3-5 days)
growth on sheep's blood: -
B.parapertussis
oxidase: -
urease: + (24 hrs)
growth rate: +(2-3 days)
growth on sheep's blood: +
86
What is the treatment of Pertussis?
-routine susceptibility testing is not performed
-organisms are susceptible to erythromycin
-erythromycin is the most recommended medicine for treatment and prophylaxis
-Erythromycin must be started during the catarrhal phase of the disease
-some possible alternatives are azithromycin and trimethoprim-sulfamethoxazole
- a few isolates of B.pertussis are resistant to erythromycin
87
What are some preventative methods used for Brucella spp.?
-acellular vaccines are available in the US
-have three formulas available DTaP, Tdap, and Td
88
DTaP vaccine
-diphtheria, tetanus, pertussis, five doses are administered to children before 6 years of age
89
Tdap Vaccine
-diphtheria, tetanus, pertussis, single dose is administered to adolescents who are 11-18 years of age or to adults who are 19-64 years of age
90
Td Vaccine
-tetanus-diphtheria adult booster is administered every 10 years
91
Herd theory of vaccination
-vaccinating everyone reduces the number of cases out there
-prevents exposure to the most vulnerable (ex: those who cannot receive the vaccine or vaccine has reduced efficacy)
92
Bordetella holmesii
-uncommon agent of sepsis
93
Bordetella bronchiseptica
-associated with respiratory diseases in dogs (kennel cough) and other animals
-transmitted to humans through close contact with infected animals
-human infections present as upper respiratory illness. Can become severe such as sepsis documented in immunocompromised patients
-Grows on Mac as nonfermenting negative bacilli
-urease positive (4 hours)
-nitrate reduction positive
94
Legionella Species
-legionella are a group of ubiquitous aerobic gram-negative bacilli
-52 species known
-approx. 25 species isolated from humans
95
What are the natural reservoirs containing legionella?
-warm aquatic habitats: lakes rivers, and marine waters
-Legionella can infect or multiply in free-living amoebae, in ciliated protozoa (Tetrahymena spp)
-L.longbeachae: associated with gardening materials such as compost and potting soil (a significant source of infection in New Zealand and Australia)
96
What are man-made reservoirs containing legionella?
-air conditioning ducts
-cooling towers
-fountains
-legionella spp. multiply within biofilms
-resistant to chlorine treatment
97
What is the most common isolate of Legionella spp.?
-legionella pneumophila
98
How many serogroups are in the Legionella spp.?
-16 serogroups
-serogroup 1 is the most significant
99
What is the typical route of infection for Legionella?
-inhalation
-can be transmitted from environmental reservoirs by aerosolized water droplets such as
-steam vents, shower heads, ice machines, HVAC systems
100
Who are predisposed to legionella spp.?
-immunocompromised
-patients with chronic lung disease
-alcoholics and heavy smokers
101
Clinical presentations of Legionella spp.
-asymptomatic
-acute febrile illness
-pneumonia
-extrapulmonary disease
102
Pontiac fever
-mild self-limiting disease
-acute flu-like upper respiratory illness 2 days post-exposure
-non-fatal
-in previously healthy individuals
-flulike symptoms last 2-5 days then subside without complications
-pathogenesis is largely unknown
-incidence in the general population unknown
-outbreak of Pontiac Fever at the Playboy Mansion (2011)
103
Legionnaires disease
-presentation of atypical pneumonia
-higher risk to immunocompromised individuals
-nonproductive cough, fever, headache, and myalgia 2-10 days post-exposure
-pulmonary infiltrates develop as time progresses
-sputum may be bloody or purulent
-rales, dyspnea, and shaking may occur
-dissemination to other body areas may occur
-
104
How did Legionnaires disease get its name?
-legionnaires convention held at the Bellevue Stratford hotel, people passed away, and more than 130 people were hospitalized with apparent pneumonia
-legionella was finally identified and isolated
-it was found in the cooling tower of the AC system which then spread through the building
105
Legionella incidence
-legionella pneumonia is one of the top 4 causes of community-acquired pneumonia
-approx. 5000 cases/year are reported
-causes 2% to 15% community-acquired pneumonia
-Incidence is likely higher than reported
-sporadic cases
-epidemic outbreaks (usually linked to AC units)
-also common agent of nosocomial pneumonia (monthly surveillance of showers, sinks, ice machines
106
Extrapulmonary disease (Legionella spp.)
-rare
-usually a result of disseminated disease (ex: wound abscesses, encephalitis, endocarditis)
107
Pathogensesis of Legionella spp.
-alveolar (lung) macrophages engulf the organisms by phagocytosis
-bacteria survive inside phagosomes and prevent phagolysosome formation
-virulence genes trick cells into transporting the organism to the endoplasmic reticulum where it replicates
-after replicating, the organisms kill the phagocyte and move on to infect more cells
108
Diagnosis of Legionella spp.
-seroconversion
-direct detection of patient samples
-rapid antigen test
-culture
109
Diagnosis of Legionella spp. (Seroconversion)
-most patients with legionellosis have a fourfold rise in anti-legionella antibodies with IFA testing
-requires acute and convalescent paired serum
-collected 4,6, and 12 weeks for the following onset of the disease
-helpful for confirming the diagnosis, not for making the diagnosis for proper treatment of the disease
110
Diagnosis of Legionella spp. (direct detection of patient samples)
-respiratory secretions- direct immunofluorescent antibody (IFA) test detects antigens. (stain/fluorescent microscope)
-low sensitivity- not routinely used anymore
111
Diagnosis of Legionella spp. (rapid antigen test)
-uses radioimmunoassay, enzyme. immunoassay, and immunochromatography
-detects only L.pneumophila serogroup 1, there are 15 other serogroups that it cannot detect and cannot detect other species of Legionella
-detects soluble antigens in urine i
112
Diagnosis of Legionella spp. (Culture)
-acceptable specimens for culture include any lower respiratory samples
-ex: sputum, tracheal aspirate, bronchial alveolar lavage, bronchial washings/brushings
-pleural fluid, pleural and lung tissue are also acceptable
-The preferred media for cultivation is selective buffered charcoal yeast extract agar plates (BCYE)
-cultures are held for 7-10 days and in 35 degrees in ambient air
113
What is Buffered charcoal yeast extract agar plate?
-BCYE base with polymixin B, anisomycin, and cefamandole
-buffer contains the growth supplement iron and L-cysteine (required by Legionella)
-charcoal: detoxifies the medium
-antibiotics: recommended to prevent overgrowth of normal respiratory flora
114
What are the culture characteristics of Legionella spp.?
-slow growing, no growth within the first 3 days
-ground glass or grainy appearance when observed under a dissecting microscope
-gram stain is faintly staining gram-negative bacilli
115
Biochemical test for legionella spp.
-legionella are inert
116
Growth characteristics of Legionella spp.
-grows on BYCE or L-cysteine-containing media only
-3 to 4 days for growth to appear
-typical colony morphology (ground glass)
117
Mass spectrometry of Legionella spp.
-legionella pneumonia will ID well (does not give serogroup)
-MS will ID other legionella species as well
118
What are the serogrouping methods of Legionella spp.?
1. direct fluorescent antibody: immunofluorescent staining specific for L.pneumophila and L.pneumophila serogroup 1
2. legionella serotyping: latex agglutination test specific for legionella species. L pneumophila and L. pneumophila serogroup 1
119
Special conciderations for legionella spp.?
-Legionnaires disease is best diagnosed using culture and urine antigen detection in combination
-Pontiac fever is limited to serologic tests to obtain a diagnosis
-culture may be inhibited by overgrowth of other commensal respiratory flora (acid wash with 0.2N KCL prior to plating)
120
Legionella spp. Treatment
-susceptibility testing is not performed on individual isolates
-typically responsive to
fluoroquinolones ( levofloxacin and moxifloxacin)
newer macrolides (azithromycin and clarithromycin)
doxycycline (erythromycin/rifampin)
** Penicillins are ineffective for therapy
