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Microbiology week 8 (FUND) > Gram Positive Rods > Flashcards

Gram Positive Rods Flashcards

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Biology 101 flashcards
1
Q

Gram positive bacilli

A

-Clostridium spp: Tetanus botuluism, gas gangrene -Corynebacterium: Diptheria and skin flora Nocardia -Bacillus sp: usually contaminant but anthrax “Bacillus” describes both the genus and the shape

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2
Q

Anaerobic gram positive bacilli

A

Bacillus and Clostridium

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3
Q

Spore that looks like a tennis racket (terminal spore)

A

Clostridium tetani

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4
Q

Spore in the center of the bug

A

Bacillus

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5
Q

Different Clostridium species

A

-Perfringens -Difficile -Tetani -Botulinum

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6
Q

Clostridium Perfringens common name and disease

A

-Gas gangrene -Vomiting -Gangrene, food poisoning

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7
Q

Clostridium Difficile common name and disease

A

-C. Diff, antibiotic associated diarrhea -diarrhea can be fatal (colon pops)

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8
Q

Clostridium Tetani common name and disease

A

-Tetanus -muscle spasms also lead to asphyxiation, also autonomic instability

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9
Q

Clostridium Botulinum common name and disease

A

-Botulism -muscle paralysis, long term binding of toxin to nerve endings - may need months on ventilator to survive

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10
Q

C. Diff pathogenesis

A

-Look for toxin (TcdA, TcdB) - disrupt G-proteins and tight junctions -Leads to fluid leakage

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11
Q

C. Diff Diagnostics

A
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12
Q

C. Botulinum basics

A
  • Large gram+ rod
  • Anaerobic spore former
  • Soil & Water
  • Needs pH >7 for growth
  • Highly potent toxin
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13
Q

C. Botulinum infection and incubation

A
  • Incubation: 12-36 hrs 
  • Adults (PRE-formed toxin) Diplopia (double vision) 
  • Any muscle weakness droopy eyelids 
  • Swallowing difficulty 
  • Breathing difficulty 
  • Babies (spore ingestion) Colonic flora not developed 
  • Floppy baby syndrome 
  • Wound infection 
  • Diagnosis: Clinical Food sent for toxin ID 
  • Anaerobic culture 
  • Treatment: supportive and trivalent antitoxin (A, B, E) but high rates of hypersensitivity
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14
Q

C. Perfringens

A

Gram positive rod with “boxcar” gram stain 

“A” strain – food disease 

Toxins

α-toxin: lethicinase 

Φ-toxin: hemolysin 

Other Diseases:

Clostridial Myonecrosis aka “gas gangrene” 

Enteritis necroticans 

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15
Q

C. Tetani

A

Anaerobic conditions spores germinate 

Toxin: Tetananospasm: 

Heavy(100kd) Cell surface receptors binding neuronal cells. 

Light 50kd: affects inhibitory systems of motor firing 

Week 1 die of unopposed muscle spasms  (opsithotonus)

Autonomic dysfunction 2nd week as toxin affect brainstem 

Works almost opposite to mechanism of botulinum

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16
Q

Anaerobic non-spore formers

A
  • Propionibacteria
  • Actinomycetes
17
Q

Propionibacteria

A

Small on gram stain 

Skin flora 

Smelly feet 

Acne 

Biofilm on lines and metal 

18
Q

Actinomycosis

A
  • Gram-positive, Branched  
  • Anaerobic (microaerophilic or facultative) 
  • Filamentous branching rods/bacilli 
  • Can be part of normal flora (mouth, GI, vagina) 
  • Usually found as part of “polymicrobial” infection >>> Not usually found in isolation 
  • Ex: Tooth flora, Pelvic inflammatory disease
19
Q

Actinomycosis clinical manifestations

A

-Draining sinus tracts!!! 

-Cervicofacial (most common)

*Dental work/trauma 

*“lumpy jaw” 

-Thoracic

*Aspiration of mouth secretions 

*Extension of “lumpy jaw” 

-Abdominal

*Penetrating trauma 

*Intestinal perforation 

20
Q

Actinomycosis diagnosis

A

Gram stain: beaded/branching GPR 

AFB stain: negative

Unlike Nocardia: partially + AFB 

“sulfur granules” 

21
Q

Aerobic spore formers

A

Bacillus Anthracis

Bacillus Cereus

22
Q

Bacillus Cereus

A

most likely contamination if pre-formed toxin is ingested: food poisoning (refried rice in chinese take-out)

23
Q

Bacillus Anthracis

A
  • wool sorters disease or pneumonia
  • malignant pustule if it is cutaneous
24
Q

aerobic non-spore formers

A
  • Listeria
  • Corynebacteria
  • Nocardium
25
Q

Listeria

A
  • contaminated food (soft cheese)
  • Listeria uses human actin tail to invade from cell to cell
  • Can moves intracellularly
  • When host defense is compromised, bloodstream infection can occur
  • important in pregnant women (harms mom since immunocompromised)
26
Q

Corynebacteria

A
  • Many species that commensals on skin: only pathogenic if get onto prosthetic material ( heart valves)
  • Corynebacterium diphtheria 
  • Prevented by vaccination. 
  • Spread: contact and droplet. 
  • Endemic in India 
27
Q

Corynebacteria diptheria diease and diagnosis

A

Disease:

  • sore throat -> airway obstruction, 
  • exotoxin => carditis &/or neuropathy 

Diagnosis:

  • Culture: black colonies on cystine-tellurite agar 
  • Loeffler’s selective media is helpful 
  • Elek’s test for toxin 
28
Q

Nocardia

A
  • Environmental saphrophytes: Soil, organic matter, water 
  • Some species are pathogenic N. brasieliensis 
  • Direct inoculum onto skin 
  • Some species are opportunistic N. asteroides 
  • Inhaled, then into lungs and/or brain
29
Q

Nocardia clinical manifestations

A

Depends on host immunity

-Immunocompetent

*Soil contaimination of skin injury

*Cutaneous disease

-Immunocompromised

*Lung disease, spread to brain

Microbiology week 8 (FUND) (9 decks)

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