Other Gram-negative Rods Flashcards
What do all gram negative rods have in common❓
- Gram -ve cell envelop
- Lipopolysaccharides LPS (virulence factor)
- Aerobic- cause infection in sites of high oxygen tension eg lungs
Mention one way gram negative rods can be classified
1. Primary pathogens of human respiratory tract: Haemophilus Bordetella Legionella
- Opportunistic pathogen:
Pseudomonas
3. Primary pathogens of animals: Brucella Francisella Pasteurella
What do you know about haemophilus influenza❓
It is pleomorphic
It has a capsule (virulence factor)
Pathogen of young children
Illnesses are sporadic in occurrence
Normal component of upper respiratory tract flora (conjunctiva, genital tract)
Haemophilus influenza…
- Is transmitted by❓
- Can cause which diseases❓
- Respiratory droplets
2. If colonization occurs in respiratory tract: Otitis media Sinusitis Epiglottitis Bronchopneumonia
If it invades the bloodstream and localizes in other areas of the body:
Meningitis
Septic arthritis
Cellulitis
Haemophilus influenza is the leading cause of bacterial meningitis
True or false❓
True
Clinically H. influenza meningitis is indistinguishable from other purulent meningitides
True or false
True
How would you diagnose an infection caused by H.influenza❓
Culture on chocolate agar
Isolation from sterile sites eg blood, CSF, synovial fluid
In meningitis: gram staining of CSF reveals: Pleomorphic Gram -ve coccobacilli Capsule (capsular swelling/quellung rxn/immunoflourescence staining)
Capsular antigen may be detected using:
Latex agglutination
Countercurrent immunoelectrophoresis
Radioimmune assay
While diagnosing a case of H. influenza infection, isolation from pharyngeal cultures may be inconclusive
True or false❓
Why❓
True
H. influenza is found normally around the respiratory tract
How can you prevent an infection caused by H.influenza❓
Immunization <2yrs (type B)
Rifampin for individuals in close with infected pt
Bordetella pertussis causes which disease❓
Small
Encapsulated coccobaccili
Grow singly or in pairs
- What disease does bordetella pertussis cause❓
- How is transmitted❓
- In the absence of Immunization, it is most common in which age group❓
- What is the incubation period of B. pertussis❓
Whooping cough
Droplets via coughing
Ages 1-5
1-3weeks
Describe the pathogenesis of infections caused by bordetella pertussis
Binds to ciliated epithelium in URT ⬇️ Production of toxins and other virulent factors ⬇️ Interference with ciliary activity ⬇️ Death of cells
The disease can be divided into phases, what are they❓
Catarrhal Phase: Fever/Malaise Rhinorrhea Mild conjunctivitis Dry/non-productive cough
Paroxysmal Phase:
Exacerbated cough followed by whoop w large mucus production
Convalesce Phase (3-4weeks, severe in infants)
How can an infection by B. pertussis be
- Prevented❓
- Diagnosed❓
- Treated❓
- Vaccine (DPT) at 2months old
2.
Clinical presentation
Culture from nasopharynx in a selective agar medium (pinpoint colonies in 3-6 days) has
Direct fluorescent antibody test
Serologic antibody test
2. Erythromycin 🚫 ⬇️ Trimethoprim-Sulfamethoxazole
Describe the legionella genus
*Cells are unencapsulated
Coccobacillary in shape
Facultative intracellular species
Aerobic and fastidious
*Require L-cysteine
Cause primarily respiratory tract infections
An infection by Legionella is an atypical, acute lobar pneumonia with multisystem symptoms.
- How can it be acquired❓
- What are it’s two distinct presentations❓
- Has an incubation period of❓
- Can be diagnosed by❓
- Can be treated using❓
- Aspiration of water containing legionella
Inhalation of contaminated aerosol
- Legionnaires diseases
Pontiac Fever
2-10days
- Culture:
Respiratory secretions using buffered charcoal yeast (pH 6.9), L-cysteine and iron
Visible colonies in 3-5days
Urinary antigen test
- Erythromycin/Azithromycin
Fluoroquinolones
🚫antibiotics for Pontiac fever
Describe pseudomonas aeruginosa
Motile (polar flagella)
Encapsulated
Obligate aerobe
⬇️Nutritional requirements
Ubiquitous
Opportunistic pathogen (found in immunocompromised pt)
Causes nosocomial: Pneumonia, UTI, Surgical site infections, Severe burn infections, Infection of chemotherapy/antibiotics therapy patients
Describe the pathogenesis of infections caused by pseudomonas aeruginosa
Attachment to tissue (pili)
⬇️
Colonization of tissue (capsule prevents removal by normal clearance mechanisms)
⬇️
Damage (toxins promote invasion and dissemination)
Infections reflecting systemic spread of P. aeruginosa include❓
Why is there a complication in choice of therapy for P. aeruginosa infections❓
1.
Bacteremia
Secondary pneumonia
Bone and joint infections
Endocarditis
CNS/Skin/Soft tissue infections
- It is often antibiotic resistant
How can infection by pseudomonas aeruginosa be identified❓
How can it be treated❓
1.
Fruity odor at bedside/lab
Isolation in blood/MacConkey agar
Serologic typing
- Aggressive antimicrobial therapy
Describe the brucella genus
Zoonosis; B. ovis causes disease in man
Unencapsulated*
Small coccobacilli
Arranged singly or in pairs
LPS (virulence factor)
Aerobic
Facultative
Intracellular parasites
How can infection by B. ovis be identified❓
How can it be treated❓
- •Detailed history/Patients occupation/Exposure to animals/Food intake
•Culture (examine for up to one month)
Plated materials: colonies in 4-5days Blood: relatively longer
- Doxycycline and Gentamycin/Streptomycin
Prolonged treatment (6 weeks) to prevent relapse
Describe the pathogenesis of B. Ovis infection
Gain of entry (cuts/abrasions in skin/GI)
⬇️
Transport via lymphatic system
⬇️
Multiplication in regional lymph nodes
⬇️
Transmission to organs of reticuloendothelial system
- What disease does B. ovis cause❓
- How is transmitted❓
- What is the incubation period of B. pertussis❓
1.
Undulant Fever
2.
Contact with infected tissue
Ingestion of unpasteurized milk
Inhalation of infected aerosols
5 days to several months
Drugs that decrease gastric acidity may increase the likelihood of transmission of B. ovis via the GI route
True or false
True
What do you know Francisella Tularensis infection
Zoonosis
Small
Pleomorphic coccobacilli
Lipid-rich capsule
Obligate aerobes
Facultative intracellular parasites
- What disease does Francisella Tularensis cause❓
- How is transmitted❓
- What are the symptoms associated with its infection❓
1.
Contact w infected animal tissue (birds/household pets)
Bite of an infected antropod
2.
Fever/Malaise/Headache/Anorexia/Fatigue
What are the risk factors associated with Francisella Tularensis❓
Summer months
> Males
Occupational risk for veterinarians, domestic livestock workers, hunters
Recreational activities w increased exposure to ticks/biting flies
Why is Francisella Tularensis a potential biological weapon❓
It’s one of the most infectious pathogenic bacteria known; requires inoculation of as few as ten organisms to cause disease
Describe the pathogenesis of a Francisella Tularensis infection
Cutaneous inoculation ⬇️ Multiplication for 3-5days ⬇️ Spread to local lymph node ⬇️ Spread to various organs or tissues
How can infection by Francisella Tularensis be diagnosed❓
How can it be treated❓
- No specific test for turalemia
Clinical presentation
History
Culture:
🚫blood
Nutritional requirement of sulfhydryl (cysteine)
- Streptomycin
Gentamycin
Describe the genus Bartonella
Facultative
Intracellular parasites
Bartonella quintana…
- Causes what disease❓
- Is spread through what vector❓
- Is diagnosed using❓
- Is treated using❓
- Trench Fever (Mild, relapsing fever with maculopapular rash
- Human body louse
* associated with poor hygiene - Culture and serological tests
- Broad spectrum antibiotics
Bartonella henselae…
- Causes what disease❓
- Is treated using❓
- Small abscesses at sources of scratch or bite
Fever
Localized lymphadenopathy
Bacillary angiomatosis
- Rifampin and doxycycline in immunocompromised pts
Pasteurella multocida…
- Can be described as❓
- Is transmitted by❓
- Can cause which diseases❓
- Is diagnosed using❓
- Is treated using❓
- Coccobacilli/rods
Exhibit bipolar staining
With some encapsulated strains
Aerobes/Facultative aerobes
Capsule and endotoxins (virulence factors)
2.
Infected animal linking a wound
Cat scratch
Animal bite
3. Fever Acute, painful cellularitis Soft tissue infections Lymphangitis Lymphadenitis Osteomyelitis/Arthritis
- Clinical history
Culture on blood agar - Wounds should be cleaned, irrigated and debrided
Surgical drainage for deep-seated infections
Prolonged antibiotic Rx using Penicillin
