Ambler Bacteria

Question 1

Gram Stain

Answer 1

Hans Christian Gram, 1884

tells if bacteria are Gram ‘POS’ or ‘NEG’.

Question 2

Gram Positives

Answer 2

Staphylococcus
Enterococcus/Streptococcus
Bacillus
Clostridium
Listeria
Corynebacterium(Diphtheroids)

Question 3

generalizations about spores

Answer 3

In a crux:
Bacillus and clostridium sporalate
Staph, Strep, Listeria and corynebacterium do not spore

My mnemonic: Spores, get Back in the Closet. Bacillus and Clostridium.

Question 4

What GP has endotoxin?

Answer 4

Listeria has eNdotoxin where most GP do not

Question 5

Staphylococcus

Answer 5

Gram Positive, catalase +, coagulase + cocci seen in Clusters.
Defenses –protein A, coagulase, hemolysins, leukocidins, penicillinase, beta-lactamases
- hyaluronidase, staphylokinase, lipase
Exotoxins

Question 6

staphylococcus coagulase tests

Answer 6

COAGulase POS = aureus
COAGulase NEG = rest, including
epidermidis
lugdenensis
saprophyticus

Question 7

Staphylococcus aureus general actions

Answer 7

Can infect head to toes and pretty much everything in-between
Really NEVER considered a contaminant.
Has a extracellular vesicles that carry beta lactamase into the surroundings
ie. There is a mixed abscess with ampicillin sensitive E.coli and MRSA. Some beta lactamase inhibitor needs to be included in the treatment.

Question 8

Staph aureus toxins

Answer 8

Enterotoxin is heat stable
TSST-1: superantigen
Coagulase
Cytolytic toxin (α toxin); pore forming toxin
Panton-Valentine leukocidin (PVL); (β toxin); pore forming toxin
seen in CA-MRSA
Exfoliatins: skin exfoliating toxin (scalded skin)

Question 9

staph aureus symptoms/ rx

Answer 9

purulent symptoms

• Boils
• septic arthritis/osteomyelitis
• Endocarditis
• Necrotizing pneumonia (salmon tinged sputum)
• intestinal

treatment is source control if possible
boils may only need I&D but many treat with abx as well.
bacteremia always treated with IV ABx

Question 10

MRSA (Meth R Staph aureus)

Answer 10

MRSA almost universally put in Contact Isolation where MSSA is not.
Penicillin introduced to public 1941 (1942)
Methicillin 1958 (1960)
SCC MEC gene
CA-MRSA late 1990’s causes recurrent boils
Vancomycin 1958 (2002)
Linezolid 2000 (2001)
Daptomycin 2003 (2005)

Question 11

VRSA

Answer 11

vanco resistant staph aureus

13 cases in US (first Detroit 2002). MI, PA, NY, DE
usually a history of recurrent MRSA and VRE skin/wound colonization with repeated vancomycin use (think dialyisis)
VAN-A gene from Enterococcus

Question 12

VISA

Answer 12

vanco intermediate staph aureus

reduced vanco suceptibility
1997 Japan
Heteroresistance? Mixed MRSA with some VISA as well
mechanism is thickened cell wall
May confer some decrease daptomycin susceptibilities

Question 13

Staphylococcus epidermidis

Answer 13

Indwelling foreign device
Usually more resistant than S.aureus = more methicillin R.
Vancomycin usually empiric choice
Treatment usually involves removal of foreign body.
Not typically as ‘virulent’ and not usually as purulent (no abscesses).
#1 cause of contaminated blood cultures

Question 14

Staphylococcus saprophyticus

Answer 14

“Honeymoon cystitis” in women
Cause of UTI
Not resistant so PCN ok.

Question 15

Enterococci

Answer 15

Historically Group D Strep so on micro reports, you may see strep species (gpc chains) that miraculously changes to enterococcus.

Clinically relevant are : faecalis and faecium

PYR + (pyrrolidonyl-arylamidase)

Highly resistant to many antibiotics
faecalis is usually less, highly resistant.
faecium is usually more, highly resistant

Question 16

enterococci hemolysis

Answer 16

Usually gamma hemolysis

Can be alpha – especially some VRE

VRE (vancomycin resistant enterococci)

• Difficult to treat
• Seen in highly abx experienced patients
• Must refer to culture sensitivity but depending on the infection and site
• -linezolid
• -daptomycin
• -tetracyclines (for non-severe infections and not really urine)
• -nitrofurantoin (for urine only)

Question 17

VRE

Answer 17

First described Europe 1980’s. felt to be from a food additive avoparcin.

Meta-analysis of 1614 enterococcal bloodstream infections had 42% VRE which has higher mortality.

Van-A, Van-B, Van-C genes
transposon. Frightened, Promiscuous bacteria!!!
(see VRSA)

Question 18

Streptococci

Answer 18

Different classification systems have been developed.

Rebecca Lancefield classified group A-V(no I/J) and was based on the C carbohydrate on wall

We use hemolysis as well to characterize today
catalase (-) unlike staph or other aerobes/facultative anaerobes

Question 19

streptococcus by hemolysis

Answer 19

alpha: green pneumoniae, viridans

Beta: pyogenes, agalactiae

gamma: enterococcus

Question 20

Streptococcus pyogenes (symptoms, etc.)

Answer 20

Group A
Pharyngitis (main cause of ‘strep throat’)
--Red, purulent tonsils
--Fever
--Lymph nodes (ant cerv)

Skin infection

• -Folliculitis
• -Cellulitis
• -Impetigo (usually Staph)
• -Necrotizing disease

Scarlet fever = fever/rash

Associated with rheumatic fever
Can cause Toxic shock syndrome 
“M” proteins (>70types) are  virulence factors
Cause of post strep glomerulonephritis
Rapidly progressing

Question 21

S. pyogenes: antibody mediated

Answer 21

Rheumatic Fever
- pharyngitis 2-4 weeks prior

Acute PSRPGN (post strep rapidly progressing glomerulonephritis)
- skin infection or pharyngitis

Question 22

Acute Rheumatic Fever

Answer 22

Major:
Migratory Arthritis (several joints in quick succession, each lasting days- 1 wk)
Carditis ( peri, epi, myo and dendo) and valvulitis (mitral stenosis as late complication)
CNS (Sydenham chorea)= St. Vitus dance
Erythema marginatum- rash
Subcutaneous nodules

Minor:
Arthralgias
Fever
Acute phase reactant elevation
Prolonged PR interval

Tx: symptomatic ie anti-inflammatories. Not proven to dec risk of rheumatic heart disease.
Abx even with negative throat culture – for stopping transmission
PCN for years to life

Question 23

Streptococcus agalactiae

Answer 23

Group B
Know this causes neonatal sepsis so pregnant moms get a screening culture antepartum
Can cause occult and sporadic disease in adults including bacteremia, SSTI, pneumonia and sepsis
esp DM
PCN DOC. Some clindamycin resistance so not reliable

Question 24

Group F = milleri group

another beta strep

Answer 24

PUS formers including abdomen, head and neck and brain abscesses!
Think of CIA – sneaky fellows.  
Strep constellatus
Strep intermedius
Strep anginosus

Question 25

Viridans Strep

Answer 25

GI flora teeth to colon A very large group of bacteria. Subacute endocarditis esp post teeth cleaning PCN DOC

Question 26

pattern, remember to treat strep with:

Answer 26

penicillin

Question 27

Streptococcus pneumoniae

Answer 27

CAPSULE with >90 serotypes that are pathogenic. - - Polysaccharide vaccine = 23 serotypes - - Conjugated vaccine = 13 serotypes #1 bacterial cause of Community Acquired Pneumonia (20-60%), Otitis Media (29-40%) and meningitis (61%) Gram positive DIPLOCOCCI

Question 28

Pneumococcal treatment

Answer 28

ceftriaxone for serious infection (meningitis, bacteremia, pneumonia) PCN still considered most potent abx resistance starting to be a concern so with serious infection, the addition to the above with vancomycin, daptomycin, linezolid warranted prior to culture susceptibilities

Question 29

Bacillus and Clostridium

Answer 29

Spore Formers Bacillus are more aerobic and clostridium anaerobic. Clostridium look like ‘tennis rackets’ Bacillus look like ‘box cars’(anthrax)

Question 30

Bacillus anthracis

Answer 30

Anthrax - Respiratory - --Widened mediastinum - GI - Meningitis - Cutaneous most common Potent eXotoxin Tx: severe - antitoxin (MAB or IG), cipro, meropenum -- Less severe, pcn, clindamycin, doxy

Question 31

Bacillus cereus

Answer 31

Boards: refried rice or penetrating eye trauma Food poisoning via heat stable enterotoxin that causes nausea/vomiting and limited diarrhea.

Question 32

Clostridium botulinum

Answer 32

Making doctors a lot of money……. Neurotoxin that blocks release of Ach from presynaptic terminals -> flaccid muscles Infants should not ingest natural honey prior to 6 months due to inability of GI immune system to neutralize spores. ->floppy baby Adults usually ingest from bad canned/smoked foods. Antitoxin and vent support.

Question 33

Clostridium tetani

Answer 33

Vaccine with Primary series and boosters q 10yrs. Usually from skin trauma with environmental exposure. Releases an eXotoxin called tetanospasmin that acts on inhibitory Renshaw cell interneurons preventing the release of GABA and glycine, both inhibitory substrates

Question 34

When to give tetanus shot vs. immunoglobulin

Answer 34

shot if unknown vaccination history or less than 3 doses previous or more than 10 years since last one TIG if dirty wound and unknown vaccination history/

Question 35

Black Tar Heroin

Answer 35

Clostridium spores documented infections necroziting disease or specific toxin disorder esp in skin poppers - Botulism - Tetanus - C. sordellii also in wounds (by the way, not common but this is in the literature for sepsis post medically induced abortion and less so spontaneous abortion. also seen post normal childbirth.)

Question 36

Clostridium difficile (C diff)

Answer 36

CDC data: 500k infections in US 2011 and 29k died within 30 days. Incidence rising and now considered most common HAI. Risk is Antibiotics!, even what we treat with but obviously less so a risk. Symptoms range from watery diarrhea +/- mucous to full blown septic colitis and death. Contact isolation due to spore formation, shedding and inadvertent contamination

Question 37

Spores

Answer 37

(C Diff!) this is the infectious problem. Found in hospital rooms on EVERYTHING (including curtains). Patient shedding with every bowel movement and probably gasseous explosions. put the toilet seat down to flush spores can survive 5 months. may be dormant in colon with normal neighborhood of flora. Patient considered infective if stool conforms to the vessel to which it is contained. Therefore contact isolation.

Question 38

C diff treatment

Answer 38

Vancomycin IV does not penetrate across colonic mucosa and oral does not really get absorbed. Probiotics are popular with some possible benefit and little risk it appears. Newest and greatest is Fecal Microbiota Transplantation. Really not new but re-discovered recently. Either it goes down from above or more commonly introduced by rectal endoscope or enema.

Question 39

Clostridium perfringens

Answer 39

Gas gangrene Three classes - Cellulitis/wound: causes crepitus - Myonecrosis: CK elevation due to muscle dmg - Diarrhea: hemorrhagic necrosis of jejunum Tx: HBO (hyperbaric O2), PCN+clinda?+IVIG?, Emergent Surgery

Question 40

Corynebacterium

Answer 40

Most are commensal flora and not pathogenic | Also reported as diphtheroids

Question 41

Corynebacteium diphtheriae

Answer 41

‘pseudomembranes’ composed of fibrin, wbc, necrotic epithelial cells Warn micro of specimen as it requires special culture techniques -- Potassium tellurite agar and Loeffler’s coagulated blood serum media. -- TREAT 1st! Antitoxin, PCN or erythro, and vaccinate as natural immunity may not occur.

Question 42

Listeria monocytogenes

Answer 42

Endotoxin GPR. Facultative intracellular org. Grows in cold temperatures such as fridge Tropism for CNS esp in young or old/immunocompromised -- also blood, amniotic fluid/placenta 3rd most common cause of neonatal meningitis. Ampicillin 1st line. Sulfa/tmp also works

Question 43

Mycobacterium

Answer 43

acid fast staining. also weakly gram positive. Grow on Löwenstein-Jensen media Most are very slow growing (weeks) except Runyon Grp IV which are fast (ie 5 days) Classified by Runyon group or Staining

Question 44

Actinomycetes

Answer 44

bacteria that act like fungi -- filamentous -- water and soil organisms Nocardia and Actinomyces

Question 45

Nocardia

Answer 45

``` Beaded, weakly GPR and weakly acid fast (but…acid fast:think mycobacterium) no sulfur granules can present like sporothrix (fungus) can disseminate including CNS infections/brain abscesses as well as pulmonary including infiltrative, nodular and cavities. (can mimic TB). N. asteroides N. brasiliensis many other species TX: Sulfa/TMP ```

Question 46

Actinomyces

Answer 46

``` Beaded GPR SULFUR granules Causes cervicfacial, abdominal infections that act like tumors. also thoracic can look like TB or cancer *** Historically pelvic disease associated with IUD’s.*** A. israelli others Tx: PCN ```

Question 47

Propionibacterium acnes

Answer 47

anaerobic slow growing gram positive rod; normal human skin and mucosal surface flora. - - Acne in teens - - surgical wounds - - Invasive deep infections with implantable devices becoming a real problem esp with orthopedic devices UE>LE Painful but not necessarily inflammatory on an aspiration of a suspected joint. Tx: PCN, Clindamycin. TCN for those acne sufferers.