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346 > Bacterial Pathogens Part II > Flashcards

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

A

k

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
Q

Helicobacter pylori

A

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
Q

Bacteria with “different” cell walls

A

Mycoplasma, Ureaplasma, and Chlamydia species
Mycobacterium species

  • M. pneumoniae
  • M. hominis
  • M. genitalium
  • U. urealyticum and U. parvum
27
Q

General characteristics
Mycoplasma, Ureaplasma, and Chlamydia species
• Mycobacterium species

A
  • 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
Q

Mycoplasma pneumoniae
• Nothing seen on Gram stain
• First called the Eaton agent
• Inhibited by antibiotics

• Main clinical syndromes

A
  • 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
Q

Mycoplasma genitalium

A

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
Q

The other “genital mycoplasmas”

A
  • 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
Q

Chlamydia species

A

• 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
Q

Chlamydia pneumoniae and C. psittaci

A
  • 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
Q

Mycobacteria

describe them

A
  • 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
Q

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)

A

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
Q

Mycobacterium leprae

A

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
Q

Non-tuberculous mycobacteria
Mycobacterial species that do not cause tuberculosis
• Most are widespread in the environment
• Six main syndromes

A 
Chronic pulmonary disease
Lymphadenitis
Soft tissue infection 
bone and joint infection
Disseminated infection
Catheter related infection
37
Q

New emerging pathogen: M. chimaera

A

• 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
Q

Normal flora – skin/mucus membranes

Nose

A 
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
Q

Normal flora – GI tract

A

Mouth:
Streptococci
Candida

Gingiva:
Prevotella
Porphyromonas

Teeth:
S. mutans
Prevotella
Porphyromonas
Fusobacterium
Streptococci
Actinomyces

Stomach/esophagous:
Lactobacilli

40
Q

Normal flora – intestine

A

Duodenum:
Lactobacilli
Streptococci

Jejunum/ileum:
Enterobacteriaceae
Bacteroides

Large bowel;
Bacteroides
Fusobacterium
E. faecalis
E. coli
Enterobacteriaceae
Clostridium
Pseudomonas

346 (16 decks)

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