Microbiology: Bacteria

How many layers does a G(+) cells have?

1. Inner Cytoplasmic Membrane

2. Outer thick peptidoglycan layer (60-100% peptidoglycan)

What is the lipid count for G(+)/G(-) cells?

G(+) cells have a low lipid count.

G(-) cells have a high lipid count.

Do G(+)/G(-) cells have an endotoxin? If so, what endotoxin?

G(+) cells do NOT release an endotoxin

G(-) does release an endotoxin — LPS aka Lipid A

Do G(+)/G(-) cells have a periplasmic space?

G(-) cells have periplasmic space

Do G(+)/G(-) cells have a porin channel?

G(+) cells do NOT have a porin channel

G(-) cells have a porin channel

How do G(+)/G(-) cells react to iysozome and penicillin attack?

G(+) cells are vulnerable

G(-) cells are resistant

Which 2 of the 4 G(+) rods produce spores?

1. Bacillus

2. Clostridium

Which 2 of the 4 G(+) cells do not produce spores?

1. Corynebacterium

2. Listeria

What type of bacteria stain better with a special stain known as acid-fast stain?

Mycobacteria

What bacteria requires a darkfield microscope in order to be seen due to them being too small?

Spirochetes

Which bacteria does not have a cell wall?

Mycoplasma, which is neither G(+)/G(-)

Name the G(+), coccus shaped, bacteria.

1. Streptococcus

2. Enterococcus

3. Staphylococcus

Name the G(-), coccus shaped, bacteria.

1. Neiserria

2. Moraxella

Name the G(+), bacillus, shaped bacters.

1. Corynebacterium

2. Listeria

3. Bacillus

4. Clostridium

5. Mycobacterium

Name the G(-), bacillus shaped, bacteria.

1. The Enterics Group

2. Haemophilus

3. Bordetella

4. Legionella

5. Yersinia

6. Francisella

7. Brucella

8. Pasteurella

9. Gardnerelia

Name the G(+), spiral shaped, bacteria.

None.

Name the G(-), spiral shaped, bacteria.

Spirochetes

1. Treponema

2. Borrelia

3. Leptospira

Name the G(+) branching filamentous growth (like fungi) bacteria?

1. Actinomyces (facultative or obligate anaerobe based on species)

2. Nocardia (partially acid fast)

Name the G(-), pleomorphic shaped, bacteria.

1. Chlamydia

2. Richettsiae

What is an obligate anaerobe?

Cannot live or grow in the presence of O2.

What is a facultative anaerobe?

Can make their own energy and can grow with or without O2

What is a microaerophile?

Can tolerate low amounts of O2 because they have superoxide dismutase (cannot catalase)

What is an obligate aerobe?

Needs O2 to live and grow

What the G(+) obligate aerobes?

1. Nocarida

2. Bacillus cereus

What the G(-) obligate aerobes?

1. Neisseria

2. Pseudomonas

3. Bordetella

4. Legionella

5. Brucella

What are the acid-fast obligate aerobes?

1. Mycobacterium

2. Nocardia

What are the G(+) facultative anaerobes?

1. Staphylococcus

2. Bacillus anthracis

3. Corynebacterium

4. Listeria

5. Actinomyces

What are the G(-) facultative anaerobes?

Most other G(-) rods

What type of aerobe is mycoplasma cosidered?

Facultative anaerobe

What are the G(+) microaerophilic bacteria?

1. Enterococcus

2. Streptococcus

   1. Some streptococcus species are facultative anaerobes

What are the G(-) microaerophilic bacteria?

1. Spirochetes

   1. Treponema

   2. Borrelia

   3. Leptospira

2. Campylobacter

What are the G(+) obligate anaerobes?

1. Clostridium

What are the G(-) obligate anaerobes?

1. Bacteroides

What does streptococcus pyogenes cause?

1. Pharyngitis

   1. Red, swollen tonsils, and pharynx

   2. Purulent exudate on tonsils

   3. Fever

   4. Swollen lymph nodes

2. Skin Infections

   1. Folliculitis

   2. Cellulitis

   3. Impetigo

   4. Necrotizing Fasciitis

3. Scarlet Fever

   1. Fever and scarlet red rash on body

4. Toxic Shock Syndrome

How do you treat Streptococcus pyogenes?

1. Penicillin G

2. Penicillin V

3. Erythromycin

4. Pencillinase-resistant infections

5. Following rheumatic fever, prophylaxis antibiotics

6. Add Clindamycin for necrotizing fasciitis or streptococcal toxic shock syndrome

How to Dx streptococcus pyogenes?

1. Gram stain

2. Culture on standard agar inhibited by bacitracin

3. Rapid antigen detection test (RADT) (throat swab)

Describe the metabolism of streptococcus pyogenes; catalase (±); aerobic; hemolysis.

1. Catalase (-)

2. Microaerophilic

3. Beta-hemolytic

   1. Enzymes destroy WBCs and RBCs

   2. Streptolysin O: O2 labile, antigenic

   3. Streptolysin S: O2 stable; non-antigenic

What are the virulences of streptococcus pyogenes?

1. M-Protein (70 types)

   1. Adherence factor

   2. Anti-phagocytic

   3. Antigenic: induces antibodies which can lead to phagocytosis

2. Lipoteichoic acid: adherence factor

3. Streptokinase

4. Hyaluronidase

5. DNAse

6. Anti-C5a peptidase

What are the toxins of Streptococcus pyogenes?

1. Erythrogenic or pyrogenic toxin (produced only by iysogenized Group A Streptococci): causing scarlet fever

2. Toxic Shock Syndrome

Describe the metabolism of Streptococcus agalactiae; catalase (±); aerobic; hemolysis.

1. Catalase (-)

2. Faculative Anaerobe

3. Beta-hemolytic

   1. Part of normal flora (25% of women carry Group B streptococci in their vagina)

What does Streptococcus agalactiae cause?

1. Neonatal meningitis

2. Neonatal pneumonia

3. Neonatal sepsis

4. Sepsis in pregnant women (secondary to fetus)

5. Increasing incidence of infections in elderly >65 y/o, diabetic patients or neurological disease causing sepsis and pneumonia

How do you treat Streptococcus agalactiae?

1. Penicillin G

How to Dx Streptococcus agalactiae?

1. Gram stain of CSF or urine

2. Culture of CSF, urine, or blood

Describe the metabolism of both non-enterococci and enterococci; G(±); shape; catalase (±); aerobic; hemolysis.

1. G(+)

2. Cocci

3. Catalase (-)

4. Facultative Anaerobe

5. Typically gamma-hemolytic; however, sometimes alpha-hemolytic

What is the virulence of both enterococci and non-enterococci?

Extracellular dextran helps them bind to heart valves

What do enterococci and non-enterococci cause?

1. Subacute bacterial endocarditis

2. Biliary tract infections

3. UTIs (especially enterococci)

   1. S. Bovis associated with colonic malignancies

What is the treatment for enterococci and non-enterococci?

1. Ampicillin, in combination with aminoglycoside (sometimes)

2. Resistant to penicillin G

3. Emerging resistance to vancomycin

4. For vancomycin resistance, consider linezolid, daptomycin, and nitrofurantoin

How to Dx enterococci and non-enterococci?

1. Gram stain

2. Culture:

   1. Enterococci: 40% bile and 6.5% NaCl

   2. Non-enterococci: only grows in bile

Describe the metabolism of Streptococcus viridans; Gram(±); shape; catalase (±); aerobic; hemolysis

1. G(+)

2. Cocci

3. Catalase (-)

4. Facultative anaerobic; some microaerophilic

5. Alpha-hemolytic

   1. Part of the normal flora (found in the nasopharynx and gingival crevices) and GI tract

What is the virulence of Streptococcus viridans?

1. Extracellular dextran helps them bind to heart valves

What does Streptococcus viridans cause?

1. Subacute bacterial enocarditis

2. Dental caries (cavities): cause by Streptococcus mutans

3. Brain or liver abscesses: caused by Streptococcus intermedius group

How do you treat Streptococcus viridans?

1. Penicillin G

How do you Dx Streptococcus viridans?

1. Gram Stain

2. Culture

3. Resistant to optochin

Describe the metabolism of Streptococcus pneuominae; Gram(±); shape; catalase (±); aerobic; hemolysis

1. G(+)

2. Cocci

3. Catalase (-)

4. Facultative anaerobe

5. Alpha-hemolytic

What is the virulence of Streptococcus pneumoniae?

1. Capsule (83 serotypes)

What are the toxins of Streptococcus pneumoniae?

1. Pneumolysin: binds cholesterol to host cell membranes (actual effect is unknown)

What does Streptococcus pneumoniae cause? (HINT: MOPS)

1. Meningitis

2. Otits media (in children)

3. Pneuomnia

4. Sepsis

How do you treat Streptococcus pneumoniae?

1. Penicillin G (IM)

2. Erythromycin

3. Ceftriaxone

4. Vaccine: made against the 23 most common capsular antigens. Vaccinate the elderly, asplenic patients, and patients with sickle cell anemia

5. Heptavalent and the newer 13 valent conjugated vaccines are effective at preventing otitis media and pneumonia

How to Dx Streptococcus pneumoninae?

1. Gram Strain: G(+), Diplococci

2. Culture does not grow in the presence of optochin and bile

3. Positive Quelling test: swelling when tested against antiserum containing anti-capsular antibodies

   1. Quelling reaction technique used to detect encapsulated bacteria (such as S. pneumoniae and H. influenzae)

Describe the metabolism of Staphylococcus saprophyticus; Gram(±); shape; catalase (±); coagulase (±); aerobic; hemolysis

1. G(+)

2. Cocci

3. Catalase (+)

4. Coagulase (-)

5. Facultative Anaerobe

6. Gamma-hemolytic

What does Staphylococcus saprophyticus cause?

1. UTIs in sexually active women

How do you treat Staphylococcus saprophyticus?

1. Penicillin

How do you Dx Staphylococcus saprophyticus?

1. Gram stain: revealing G(+) cocci in clusters

2. Culture: Gamma Hemolytic

3. Metabolic: Catalase (+) and Coagulase (-)

Describe the metabolism of Staphylococcus epidermidis; Gram(±); shape; catalase (±); coagulase (±); aerobic; hemolysis

1. G(+)

2. Coagulase (-)

3. Facultative Anaerobe

What are the virulences of Staphylococcus epidermidis?

1. Polysaccharide capsule; adheres to a variety of prosthetic devices. Forms a biolfim.

2. Highly resistant to antibitoics

What does Staphylococcus epidermidis cause?

1. Nosocomial infections:

   1. Prosthetic joints

   2. Prosthetic heart valves

   3. Sepsis from intravenous lines

   4. UTIs

2. Frequent skin contaminant in blood cultures!

How do you treat Staphylococcus epidermidis?

1. Vancomycin (since resistant to multiple antibiotics)

How do you Dx Staphylococcus epidermidis?

1. Gram stain: reveals G(+) cocci in clusters

2. Culture

3. Metabolic

   1. Catalase (+)

   2. Coagulase (-)

Describe the metabolism of Staphylococcus aureus; Gram(±); shape; catalase (±); coagulase (±); aerobic; hemolysis

1. G(+)

2. Cocci

3. Catalase (+)

4. Coagulase (+)

5. Facultative Anaerobe

6. Beta-hemolytic

What is the virulence factor of Staphylococcus aureus?

1. Protective Proteins:

   1. Protein A: binds IgG, preventing opsonization and phagocytosis

   2. Coagulase: allows fibrin formation around organism

   3. Hemolysis

   4. Leukocidins

   5. Penicillinase

2. Tissue Destorying Proteins

   1. Hyaluronidase: breaks down connective tissue

   2. Staphylokinase: lyses formed clots

   3. Lipase

What are the toxins of Staphylococcus aureus?

1. Enterotoxin: food poisoning

2. Toxic Shock Syndrome Toxin (TSST-1)

3. Exfoliatin: scalded skin syndrome

What does Staphylococcus aureus cause?

1. Exotoxin Dependent

   1. Gastroenteritis

   2. Toxic Shock Syndrome:

      1. High Fever

      2. Nausea

      3. Emesis

      4. Watery diarrhea

      5. Erythematous rash

      6. Hypotension

      7. Desquamation of palms and soles

   3. Scalded skin syndrome

2. Direct Invasion

   1. Pneumonia

   2. Meningitis

   3. Osteomyelitis (in children)

   4. Acute bacterial endocarditis

   5. Septic arthritis

   6. Skin infection

   7. Bacteremia/sepsis

   8. UTIs

How do you treat Staphylococcus aureus?

1. Penicillinase-resistance penicillins

   1. Nafcillin (IV) and Dicloxacillin (oral)

2. 1st generation cephalosporins:

   1. Cefazolin (IV)

   2. Cephalexin (Oral) + Clindamycin (IV)

3. Clindamycin (IV and oral)

How do you treat MRSA caused by Staphylococcus aureus?

1. Vancomycin (IV)

2. Daptomycin (IV)

3. Clindamycin (IV and Oral)

4. Trimethoprim-sulfamethoxazole (IV and oral)

5. Linezolid (IV and oral)

6. Ceftaroling (IV)

7. Telavancin (IV)

8. Dalbavancin (IV)

9. Oritavancin (IV)

10. Tedizolid (IV and PO)

11. Tigecycline

12. Delafloxacin

How do you Dx Staphylococcus aureus?

1. Gram stain: G(+), cocci in clusters

2. Culture: Beta-hemolytic and produces golden yellow pigment

3. Metabolic: Catalase (+) and Coagulase (+)

4. Polymerase chain reaction (PCR) detection of ribosomal RNA

Describe the metabolism of Bacillus anthracis.

1. Aerobic specifically, Facultative Aerobe

How is Bacillus anthracis transmitted?

1. Spore forming (endospores)

   1. Cutaneous

   2. Inhalation

   3. Ingestion

Describe the reservoir for Bacillus anthracis.

1. Herbivores

   1. Sheep

   2. Goats

   3. Cattle

What are the virulence factors of Bacillus anthracis?

1. Unique protein capsule (polymer of gamma-D-glumatic acid): antiphagocytic

2. Non-motile

3. Virulence depends on acquiring 2 plasmids. One carries the gene for the protein capsule; the other carries the gene for its exotoxin