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Bacterial Pathogens Part II Flashcards

1
Q

Anaerobic bacteria
Gram-negative
Rods/bacilli

A

Bacteroides species
Porphyromonas species
Prevotella species
Fusobacterium species

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2
Q

Anaerobic bacteria
Gram-negative
Cocci/spheres

A

Veillonella species

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3
Q

Anaerobic bacteria
Gram-positive
Rods/bacilli

A

Clostridium species
Actinomyces species
Propionibacterium species
Lactobacillus species

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4
Q

Anaerobic bacteria
Gram-positive
Cocci/spheres

A

Finegoldia species
Anaerococcus species
Peptostreptococcus species

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5
Q

Anaerobic bacteria

Definition

A

bacteria that grow in the absence of free oxygen but fail to multiply in the presence of oxygen
• Obligate or aerotolerant
• Do not use oxygen as a terminal electron acceptor with varying ability to tolerate the presence of oxygen
• Natural habitats: widespread in the environment but, in humans, found in the mouth, GI tract, GU tract, and on the skin
• Often have infections of “mixed anaerobes” due to the bacteria entering a breach of a mucosal or cutaneous barrier

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6
Q

Bacteroides species

infection

A

Gram-negative Rods/bacilli
• Make up ~20-30% of bacterial gut flora
• Members of the B. fragilis group are most clinically important
• Usually contribute to polymicrobial infections

  • Escape from the gut:
  • Abscess formation (abdomen, brain, liver, pelvis, lungs)
  • Bacteremia
  • Virulence factors:
  • Capsule, extracellular enzymes, lipopolysaccharide, pili
  • Enterotoxin (some B. fragilis group strains only)
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7
Q

Porphyromonas species

infection

A

Gram-negative Rods/bacilli
• Porphyromonas gingivalis is a well-known pathogen
• All species produce pigment
• Implicated in dental disease
• Periodontitis, necrotizing ulcerative gingivitis, infected root canals, periimplant lesions, and acute apical abscesses
• Also can form abscesses in multiple body areas
• Bacteremia
• Virulence factors:
• Capsule, extracellular enzymes, LPS, pili

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8
Q

Prevotella species

infection

A

Gram-negative Rods/bacilli
• Found predominantly in the oral cavity
• Fluoresce brick-red under UV light
• Involved in all types of dental infections
• Often isolated from human bite wound infections
• Abscesses
• Bacteremia

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9
Q

Fusobacterium species

infection

A

Gram-negative Rods/bacilli
Fusobacterium necrophorum is the most clinically
significant
• Pleomorphic, coccoid to long, curled forms
• Dental infections
• Tonsillitis
• Abscesses (periotonsillar, deep neck spaces, brain, lung, bone, joint, soft tissue, and others)
• Bacteremia
• Lemierre’s Syndrome:

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10
Q

Actinomyces species

infection

A
  • Aerotolerant Gram-positive rods
  • Over 40 species identified
  • Found in oral, GI, and GU body sites
  • Often grow as filamentous, branching rods
  • “Molar-tooth” morphology
  • Actinomycosis
  • Slow, chronic infection
  • Abscesses
  • Crosses tissue boundaries
  • Sinus tract formation
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11
Q

Propionibacterium species

A 
Gram-positive Rods/bacilli 
• Propionibacterium acnes is the most significant (now has a new name:
“Cutibacterium acnes”)
• Aerotolerant, Grampositive rod
• Found naturally on the skin
• Good at forming biofilms
• Prosthetic joint infections
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12
Q

Clostridium species

4 species

A
  • Gram-positive rods, spore formers
  • > 200 species
  • Toxin-producing pathogens

C. tetani
C. botulinum
C. difficile
C. perfringens

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13
Q

C. tetani
C. botulinum
C. difficile
C. perfringens

A

C. tetani: Soil, penetrating injuries
- Tetanus toxin Tetanus

C. botulinum: Soil/dust, homecanned foods, raw
honey
- Botulinum toxin Botulism difficile

C. difficile; Antibiotic use, carriage in other patients
Toxin A (enterotoxin)
Toxin B (cytotoxin)
- Diarrhea +/- complications

C. perfringens: Foodborne, normal GI flora

  • C. perfringens enterotoxin
  • Alpha and theta toxins
  • Diarrhea
  • Gas gangrene
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14
Q

Clostridium tetani

symptoms

A
  • Severe muscle spasms following a penetrating injury
  • Trismus (lockjaw)
  • Stiff neck
  • Arched back
  • Periods of apnea
  • Rigid abdomen
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15
Q

Clostridium botulinum

symptoms

A 
• Bilateral cranial nerve
dysfunction
• Blurred or double vision
• Ptosis (eyelid drooping)
• Dysphagia
• Dysarthria
• Facial weakness
• Symmetric, descending
weakness/paralysis
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16
Q

Clostridioides difficile

symptoms

A
  • Antibiotic-associated diarrhea
  • Watery diarrhea
  • Severe colitis
  • Pseudomembranous colitis
  • Toxic megacolon
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17
Q

Clostridium perfringens

symptoms

A

Gas gangrene (clostridial myonecrosis)
• C. perfringens related gas gangrene often due
to trauma with deep penetrating injuries
Grow in deep tissue that grows toxin and need ICU support
Tissue devitalized

18
Q

spiral/curve-shaped bacteria

Systemic disease

A

treponema pallidum
Borrelia burgdorferi
Leptospira species

19
Q

spiral/curve-shaped bacteria

Gastrointestinal disease

A

helicobacter pylori
Campylobacter jejuni
Vibrio cholerae

20
Q

Treponema pallidum

A

Spirochete (spiral-shaped) bacterium
• Causes syphilis
• Sexually-transmitted infection with a long, controversial history treatment withheld from male patients with syphilis in order to
study the natural history of the disease

21
Q 
Syphilis
primary
secondary
latent
tertiary
congential stages

see slide 21

A

Primary: Chancre, lymphadenopathy ~3 weeks
Secondary: Rash, fever, malaise, lymphadenopathy,
mucosal lesions, condyloma lata, alopecia,
meningitis, headaches
2-12 weeks

Latent: Asymptomatic <1 year = early
>1 year = late

Tertiary: Cardiovascular, Neurosyphilis, Gummatous
Congenital: Mucocutaneous lesions, osteochondritis,
anemia, hepatosplenomegaly,
neurosyphilis

caused by Treponema pallidum

22
Q

Borrelia burgdorferi

A
  • Another spirochete
  • Causative agent of Lyme disease
  • Transmitted through tick bites
23
Q

see slide 26 for Lyme disease

24
Q

Leptospira species

A
  • Another spirochete
  • 22 Leptospira species described
  • Rodents are the most important reservoir
  • Gains entry into humans via cuts, mucous membranes, ingestion, or inhalation
  • Wide range of severity (mild → death)
  • Fever, chills, headache, myalgias (>80%)
  • Nausea, vomiting, diarrhea (~30%)
  • Conjunctival suffusion (~50%)
  • Respiratory symptoms (~30%)
  • Kidney failure (40-70%)
  • Liver dysfunction (>50%)
  • Meningitis (50-85%)
25
Helicobacter pylori
Gram-negative, curved bacterium • Found almost exclusively in humans • Its discovery and an atypical experiment showing its relationship to gastritis led to Barry Marshall winning the Nobel Prize • Peptic ulcer disease • Gastritis • Gastric adenocarcinoma • Gastric mucosa associated lymphoid tissue lymphoma
26
Bacteria with “different” cell walls
Mycoplasma, Ureaplasma, and Chlamydia species Mycobacterium species * M. pneumoniae * M. hominis * M. genitalium * U. urealyticum and U. parvum
27
General characteristics Mycoplasma, Ureaplasma, and Chlamydia species • Mycobacterium species
* Small (~0.5 µm) * Coccoid-shaped to tapered rods * Fastidious * No cell wall and therefore cannot be Gram stained * Classic colony appearance: “fried egg” shape
28
Mycoplasma pneumoniae • Nothing seen on Gram stain • First called the Eaton agent • Inhibited by antibiotics • Main clinical syndromes
* Tracheobronchitis * URTI – coryza, pharyngitis, otitis media * Atypical pneumonia (up to 20% of CAP) * Others * Skin/MMs, heart, CNS, hematologic disease, kidneys, MSK * Atypical pneumonia * Bilateral patchy opacities
29
Mycoplasma genitalium
Discovered in 1981 from urethral swabs of men with non-gonococcal urethritis • Extremely slow-growing and fastidious • Sexually transmitted • Females: cervicitis and pelvic inflammatory disease • Males: urethritis
30
The other “genital mycoplasmas”
* M. hominis, U. parvum, U. urealyticum * Believed for many years to be causative agents of genital tract disease * Role now is less clear * Often colonizing the female genital tract without causing symptoms (ie, normal flora) * Some studies only implicate U. urealyticum as causing urethritis in males
31
Chlamydia species
• C. trachomatis, C. pneumoniae, and C. psittaci • Lack a cell wall • Intracellular pathogens • Lifecycle includes the infective elementary bodies and reticulate bodi Multiple serotypes with different disease associations A, B, C Trachoma: • Leading cause of blindness worldwide D-K Urethritis, cervicitis, and others: STI, 40-95% ASYMPTOMATIC Males: urethritis, urethral discharge, dysuria, testicular pain, conjunctivitis • Females: cervicitis, vaginal discharge, dysuria, dyspareunia, conjunctivitis • Newborns: conjunctivitis and pneumonia L1, L2, L3 Lymphogranuloma venereum • Primary: painless small papule/ulcer • Secondary: painful enlarged lymph nodes (inguinal/anorectal) • Tertiary: anogenital fibrosis, strictures, with elephantiasis and extensive ulceration
32
Chlamydia pneumoniae and C. psittaci
* Similar to M. pneumoniae, cause atypical pneumonia * C. pneumonia: transmitted between humans via respiratory secretions * Causes 0-44% of community-acquired pneumonia * C. psittaci: causes ornithosis or psittacosis * Found in the feces, urine, and respiratory secretions of birds * Psittacine birds at highest risk
33
Mycobacteria | describe them
* A large group of organisms that do not Gram stain well due to a high content of complex lipids in their cell wall * Require special staining methods (eg, Ziehl-Neelsen staining) and are referred to as “acid fast bacilli” (AFB) * Long generation times (~20 hours vs 30 minutes for E. coli)
34
Mycobacterium tuberculosis • Actually a complex of organisms (made up of 10 species) • Causes a chronic, highly infectious pulmonary disease • Referred to as the “white plague” or “consumption” • Prior to the use of antibiotics, open air and sunshine were the cornerstones of therapy (in a sanatorium)
Pulmonary disease • Inhalation of bacteria into the alveoli, establish infection, form granulomas • Chronic fever, cough, dyspnea, anorexia, wasting Extra-pulmonary disease • Lymph nodes, bones, vertebra, joints, GI, GU, eyes, skin, pericarditis, meningitis • Tuberculosis remains one of the world’s deadliest communicable diseases
35
Mycobacterium leprae
Extremely slow-growing AFB (generation time ~12.5 days) • Causes leprosy: a chronic, granulomatous, debilitating disease • Cannot be cultured in the laboratory • Skin lesions: hypopigmented or erythematous • Reduced sensation, weakness, peripheral nerve thickening • Peripheral sensory nerve damage
36
Non-tuberculous mycobacteria Mycobacterial species that do not cause tuberculosis • Most are widespread in the environment • Six main syndromes
``` Chronic pulmonary disease Lymphadenitis Soft tissue infection bone and joint infection Disseminated infection Catheter related infection ```
37
New emerging pathogen: M. chimaera
• A pathogen transmitted during open heart surgery • Found to contaminate heatercooler units for keeping cardioplegia and patient blood at optimal temperatures • Aerosolized organism lands in the surgical field
38
Normal flora – skin/mucus membranes | Nose
``` nose: S. aureus S. epidermidis Diphtheroids Streptococci ``` ``` skin/groin/perineum: S. epidermidis S. aureus Diphtheroids Streptococci Pseudomonas Anaerobes Candida ``` ``` urethra and vagina: S. epidermidis Diphtheroids Streptococci Gram-negative rods ```
39
Normal flora – GI tract
Mouth: Streptococci Candida Gingiva: Prevotella Porphyromonas ``` Teeth: S. mutans Prevotella Porphyromonas Fusobacterium Streptococci Actinomyces ``` Stomach/esophagous: Lactobacilli
40
Normal flora – intestine
Duodenum: Lactobacilli Streptococci Jejunum/ileum: Enterobacteriaceae Bacteroides ``` Large bowel; Bacteroides Fusobacterium E. faecalis E. coli Enterobacteriaceae Clostridium Pseudomonas ```

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