AEROBIC NONSPORE- FORMING GRAM- POSITIVE BACILLI

Question 1

AEROBIC NONSPORE-FORMING GRAM-POSITIVE BACILLI

Answer 1

• Corynebacterium diphtheriae
• Listeria monocytogenes
• Erysipelothrix rhusiopathiae
• Actinomycetes
   Nocardia
   Actinomycetoma

Question 2

Corynebacterium diphtheriae

Answer 2

• clubbed-shaped, resemble Chinese letters or palisades
• high guanosine plus cytosine content
• occurs in the respiratory tract, in wounds, or on the skin
• Transmission: droplet or contact

Question 3

Corynebacterium diphtheriae Toxin

Answer 3

• Fragment A – inhibits polypeptide chain elongation (arrests protein synthesis)
• Fragment B – binds to host cells for receptor-mediated endocytosis

Question 4

Corynebacterium diphtheriae
Clinical Findings:

Answer 4

• Respiratory Diphtheria

 grayish pseudomembranes over the
tonsils, pharynx, and larynx - necrotic
epithelium becomes embedded in
exuding fibrin and red and white cells

 bull neck - lymph nodes in the neck
enlarge, edema of the entire neck, with distortion of the airway

 sore throat, low-grade fever
 prostration, dyspnea, suffocation

• Cutaneous Diphtheria
   membrane may form on an infected wound that fails to heal

Question 5

Corynebacterium diphtheriae Diagnosis

Answer 5

• Dacron swab
• Culture Medium: Tellurite medium,
  Löffler serum medium
• Identification: Babes-
  Ernst/Volutin/Metachromatic Granules
   red when stained with methylene blue
   beaded appearance
• Elek test – to determine whether the
  organism is able to produce the
  diphtheria toxin

Question 6

Corynebacterium diphtheriae Treatment and Prevention

Answer 6

• Treatment
   Penicillin, Macrolides
   Antitoxin
• Prevention
   Diphtheria toxoid in DPT

Question 7

Listeria monocytogenes

Answer 7

• can survive at:
   refrigerator temperatures (4°C)
   low pH
   high salt conditions
• foodborne pathogen
• Microscopy: tumbling end-over-end motility
• Motility Medium: umbrella growth
  pattern

Question 8

Listeria monocytogenes Clinical
Findings:

Answer 8

Perinatal Listeriosis

• Granulomatosis infantiseptica
   early onset
   infection in utero and disseminated form
   neonatal sepsis, pustular lesions, and granulomas
   death
• Neonatal meningitis
   late onset

Question 9

Listeria monocytogenes Clinical
Findings:

Answer 9

Adult Listeriosis

• Immunocompetent
   mild, self-limiting febrile gastroenteritis
   fever, chills, headache, myalgias, abdominal pain, and diarrhea
• Adult
   meningoencephalitis, bacteremia, and focal infections

Question 10

Erysipelothrix rhusiopathiae

Answer 10

• H2S producing
• Culture Medium: Triple Sugar Iron
   black colonies
• causes erysipelas in swine
• causes erysipeloid in humans
   seal finger/whale finger
   raised, well circumscribed,
  violaceous
• greatest risk:
  fishermen, fish handlers, butchers, and others who have contact with animal products

Question 11

Actinomycetes

Answer 11

• tend to form chains or filaments
• As the bacilli grow, the cells remain together after division to form elongated chains of bacteria with
  occasional branches.
• Differentiated based on acid-fast staining:
   Truly acid fast: Mycobacterium
   Weakly acid fast: Nocardia
   Non-acid fast: Streptomyces, Corynebacterium, Actinomadura

Question 12

Nocardia

Answer 12

• filamentous organisms with hyphae-like branching
• form extensive branching substrates and aerial filaments that fragment, breaking into coccobacillary cells
• weakly acid fast: contain mycolic acids that are shorter chained
  than those of Mycobacteria
• Transmission: through inhalation

Question 13

Nocardia

Answer 13

Nocardiosis

 an opportunistic infection in corticosteroid treatment, organ
transplantation, AIDS, and alcoholism
 subacute to chronic pulmonary infection (chronic lobar pneumonia)
 may disseminate to other organs

• Treatment:
   Cotrimoxazole (DOC)

Question 14

Actinomycetoma

Answer 14

• Mycetoma (Madura foot)

 a localized, slowly progressive, chronic infection that begins in subcutaneous tissue and spreads
to adjacent tissues

 destructive and often painless

Causative Agent: Actinomadura madurae, Streptomyces somaliensis, Actinomadura pelletieri, Nocardia asteroides, and N. brasiliensis

Treatment:
 combinations of streptomycin, trimethoprim– sulfamethoxazole, and dapsone
 amputation

Question 15

Streptomyces sp
source of antibiotics

Answer 15

Streptomyces nodosus
Amphotericin B
Streptomyces Noursei
Nystatin
Streptomyces LINcolnensis
LINcomycin
Streptomyces Orientalis
VancOmycin
Streptomyces griSeus
Streptomycin
Streptomyces orChidaceus
Cycloserine
Streptomyces veNEzuelae
ChloramphENicol
Streptomyces ERYTHraea
ERETHromycin (Ilotycin)
Streptomyces roseOsporus
DaptOmycin