Update on the 2012-2013 CLSI Standards for Antimicrobial ... · 8/28/2012 jhindler CLSI M100-S22...

8/28/2012

jhindler CLSI M100-S22 Update

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Update on the 2012-2013 CLSI Standards for

Antimicrobial Susceptibility Testing:

What’s New with the

Gram Positive Cocci?

Susan Sharp, Ph.D.

Director, Kaiser Permanente Laboratory

Portland, Oregon, USA

[email protected]

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CLSI AST Standards – January 2012

M100-S22 Tables (2012)*

M02-A11 Disk Diffusion Method (2012)^

M07-A9 MIC Method (2012)^

* M100 updated every year

# M02, M07 updated every 3 years

Summary of Major Changes

Changes to CLSI documents are summarized in the front of each document.

Information listed in boldface type is new or modified since the previous edition of M100 document.

Recent breakpoint addition/revision dates are listed in the front of M100-S22.

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Today’s Review: 2012-2013 changes

Staphylococcus species

Streptococcus pneumoniae

b-Streptococcus species

Enterococcus species

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Penicillin testing

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Staphylococcus spp. – Penicillin

The story…..

> 90% of staphylococci are penicillin “R”

Penicillin rarely considered for treatment of staphylococcal infections

…BUT - Penicillin might be considered for infections requiring lengthy therapy (e.g., endocarditis, osteomyelitis) IF penicillin were known to be “S”

Some Staphylococcus spp. that test “S” to penicillin by MIC or disk diffusion may actually possess a β-lactamase (BL) that may cause the patient to fail penicillin therapy

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Staphylococcus spp. – Penicillin

CLSI Previous recommendation:

Perform induced nitrocefin BL test before reporting penicillin as “S” if:

zone diameter ≥29 mm

MIC ≤0.12 µg/ml

PCR for the blaZ β-lactamase gene may be considered

Penicillin Breakpoints

MIC (µg/ml) Zone (mm)

S I R S I R

≤0.12 - ≥0.25 ≥29 - ≤28

7 Reference: M100-S21. Table 2C. Page 70

Induced ß-lactamase (BL) Test

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-Sub isolate to blood agar

-Induction: Drop disk to induce BL

production (e.g., oxacillin or cefoxitin)

-Incubate overnight

-Test cells from periphery of zone

-If BL positive, report penicillin R Pos Neg

Staphylococcus aureus

β-lactamase (BL)

Induced nitrocefin BL test usually, but not always, detects staphylococcal BL

Other BL tests are more sensitive for BL:

Cloverleaf test

Penicillin disk zone edge test

blaZ gene PCR not optimal for BL

blaZ codes for BL production

Several types of blaZ genes

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Staphylococcus aureus β-lactamase (BL) Study

348 MSSA (low penicillin MICs) characterized for blaZ by PCR:

303 PCR negative

45 PCR positive

Methods:

Penicillin MICs

Phenotypic BL tests Nitrocefin - Cefinase

Nitrocefin - Dryslide

Cloverleaf assay

Penicillin disk zone edge

10 *Statens Serum Institut (Denmark), CDC (Atlanta), MGH (Boston)


BL Study

Pen MIC

(µg/ml)

blaZ functional

Neg Pos

0.008 2

0.016 15

0.032 180 1

0.06 90 5

0.12 15 17

0.25 1 14

0.5 4

1.0

2.0 2

4.0 1

303 45

• 1 blaZ neg and penicillin “R”

• 23 blaZ pos and penicillin “S”

Reference: CLSI Agenda Book January 2011.

S

R

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Cloverleaf Assay for

β-lactamase +

S. aureus

• 5% sheep blood agar

• S. aureus ATCC 25923 as the

indicator BL+ organism

• 1 unit penicillin disk

• Negative (penicillin-S) strain

• Some difficulties reading

Reference: CLSI Agenda Book January 2011.

Isolates A-D are all

BL positive

A

B

C

D

BL negative

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13

β-lactamase positive

β-lactamase negative

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Staphylococcus aureus Disk Zone Edge Test (10 U penicillin disk and standard disk diffusion method)

Fuzzy / “beach” =

β-lactamase negative,

Penicillin - S

Sharp / “cliff” =

β-lactamase positive,

Penicillin - R

S. aureus QC:

Neg - ATCC 25923

Pos - ATCC 29213 (supplemental QC)

Reference: M100-S22. Table 2C Supplemental Table 1. Page 83


3 Lab BL Study Results (N=348)

Test Sensitivity Specificity

Cefinase 77% 100%

Dryslide 88% 100%

Cloverleaf 100% 100%

Penicillin disk zone edge 96% 100%

15 Reference: CLSI Agenda Book January, 2011

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Penicillin MIC ≤0.12 µg/ml

Nitrocefin β-lactamase

positive

Report penicillin “R”

Nitrocefin β-lactamase

negative

Perform penicillin disk zone-edge test

≥ 29 mm fuzzy

Report penicillin “S”

≥ 29 mm sharp

Report penicillin “R”


Penicillin (MIC ≤0.12 µg/ml) Reporting

Note: If doing disk diffusion routinely, just examine zone edge for those with zone sizes of > 29mm.

M100-S22. Table 2C Supplemental Table 1. Page 80

A A B

NEW RECOMMENDATION:

Added ‘penicillin disk zone edge test’ for BL

production in S. aureus

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Staphylococcus spp. – Penicillin Staphylococcus spp. –

Penicillin Optional Strategy

Report penicillin if “R”

Suppress penicillin if “S” and add note “Contact laboratory if penicillin results needed”

If penicillin “S” and penicillin results needed, perform:

S. aureus Nitrocefin BL test , and if negative

Penicillin zone edge test

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S. aureus Isolates where penicillin zones are ≥29 mm or penicillin MICs are ≤0.12

µg/ml, perform a penicillin ‘disk zone edge test’ before reporting as penicillin susceptible.

NOTE:

S.lugdunensis isolates where penicillin zones are ≥29 mm or penicillin MICs are ≤0.12 µg/ml, perform an induced nitrocefin assay or other CLSI reference method on isolates before reporting as penicillin susceptible.

The penicillin disk zone edge test was shown to be inferior as compared to the induced nitrocefin assay and should not be used with S.lugdunensis.

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Action Items Staphylococcus

Oxacillin – Intermediate

Table 2C / Note (13)

If oxacillin-I results (disk diffusion testing) are obtained for S.aureus, perform testing for mecA or PBP 2a, the cefoxitin MIC or cefoxitin disk test, an oxacillin MIC test, or the oxacillin-salt agar screening test. Report the result of the alternative test rather than the oxacillin-I result.

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Staphylococcus

Oxacillin – Resistance

Table 2C / Note (12)

If oxacillin-R staphylococci report penicillin as resistant or do not report.

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Staphylococcus

Disks per plate – clarification

12 disks only on a 150mm plate


Do not measure zone of inhibition of hemolysis

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Enterococcus – Vancomycin (4/32)

For isolates with MICs of 8-16 mg/ml

Perform tests are listed in 2D-Supplemental Table 1

2D-Supplemental Table 1

Motility

Pigment

E.gallinarum (non-pigmented, motility +)

E.casseliflavus (pigmented yellow, motility +)

Other Enterococcus (non-pigmented, non-motile)

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Enterococcus - Vancomycin

Alternative inoculum method provided for vancomycin resistance screen test

2D-Supplemental Table 1

OLD: 1-10mL of a 0.5 McFarland suspension spotted onto agar surface (agar = 6mg/ml vanco in BHI agar)

NEW (added): Alternatively, using a swab dipped in the suspension and the excess liquid expressed, spot an area 10-15mm in diameter or streak a portion of the plate.

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Predicting susceptibility to Fluoroquinolones

Isolates susceptible to levofloxacin are predictably susceptible to gemifloxacin and moxifloxacin.

Isolates susceptible to gemifloxacin or moxifloxacin can not be assumed to be susceptible to levofloxacin.

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Streptococcus pneumoniae &

b-Streptococcus

Disks per plate – clarification



Do not measure zone of inhibition of hemolysis

(for Viridans streptococci as well)

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b-Streptococcus

Table 2H-1 Supplemental Table 1

(inducible clindamycin resistance)

Included new comment regarding CDC recommendations:

“The 2010 CDC guidelines on prevention of group B streptococcal disease in neonates recommend that colonization isolates from pregnant women with severe penicillin allergy (high risk for anaphylaxis) should be tested for inducible clindamycin resistance.”

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b-Streptococcus

Table 2H-1

Daptomycin

Disk diffusion testing is not reliable

(previously indicated for the staphylococi)

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2013 ! !

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Staphylococcus - 2013

All cephalosporins/many penicillins currently in the 2012 Table 2C will be removed.

Deleted all β-lactam breakpoints except penicillin, oxacillin [cefoxitin], and ceftaroline .

Statements will be made to indicate that results for cephalosporins and other b-lactam antibiotics (that are appropriate for staphylococci treatment) can be predicted from the results of oxacillin MIC, cefoxitin MIC, or cefoxitin disk diffusion testing.

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Penicillins,

b-lac inhib combos

Cephems

Carbapenems


Rationale for deleting breakpoints for b-lactams

(except pencilllin, oxacillin [cefoxitin], & ceftaroline) from the CLSI M100 tables for staphylococci:

Current breakpoints are most likely inaccurate They were ‘Grandfathered’ into the staphylococcal tables with

other major table over-hauls in the early 2000’s.

Can deduce anti-staphylococcal b-lactam results from penicillin

and oxacillin [cefoxitin] results.

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Oxacillin disk diffusion testing will be removed form the staphylococci charts.

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Detection of oxacillin resistance: In most staphylococcal isolates, oxacillin resistance is mediated by mecA-

encoding the penicillin-binding protein 2a (PBP 2a, also called PBP2‘).

Other mechanisms of oxacillin resistance are rare and include a novel mecA homologue (eg, mecC)REF which may not be detected by tests for mecA or PBP 2a.

Isolates that test positive for mecA or PBP 2a should be reported as oxacillin resistant.

Isolates for which either the oxacillin MIC, cefoxitin MIC, or cefoxitin disk diffusion test is in the resistant range should also be reported as oxacillin resistant.

37 REF: Stegger M, Andersen PS, Kearns A, Pichon B, Holmes MA, Edwards G, Laurent F, Teale C, Skov R, Larsen AR. Rapid detection,

differentiation and typing of methicillin-resistant Staphylococcus aureus harboring either mecA or the new mecA homologue mecA(LGA251).

Clin Microbiol Infect. 2012;18(4):395-400 .


Table 1A and Table 2C: 2013

Adding for doxycycline and minocycline to not report on organisms

isolated from the urinary tract.

Removing telithromycin due to black box warning from FDA; and

changing Test/Report Group from ‘B’ to ‘O’ in Table 2C.

Adding footnote to indicate that daptomycin should not be reported for

isolates from the lower respiratory tract.

Removing quinupristin/dalfopristin as it is not FDA cleared for MRSA or

coagulase negative staphylococci. Stating that for isolates of MSSA

there are much better drugs to use for treatment with less toxicity. Changing Test/Report Group from ‘C’ to ‘O’ in Table 2C.

Removing amikacin, kanamcin, netilimicin and tobramycin and their

breakpoints. Only gentamicin will remain. Added note to gentamicin-S isolates that it is to be used only in combination with

other active agents

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Streptococcus pneumoniae - 2013

New (revised) tetracycline disk diffusion and MIC interpretive criteria.

New doxycycline disk diffusion and MIC interpretive criteria.

Clarified that isolates of S. pneumoniae from CSF can also be tested against vancomycin using the MIC or disk method.

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Streptococcus pneumoniae - 2013

PENICILLINS

For nonmeningitis isolates, a penicillin MIC of ≤0.06 mg/mL (or oxacillin

zone ≥ 20 mm) can predict susceptibility to the following β-lactams:

penicillin (oral or parenteral), ampicillin-sulbactam, amoxicillin, amoxicillin-clavulanic acid

cefaclor, cefdinir, cefditoren, cefepime, cefotaxime, cefpodoxime, cefprozil, ceftaroline, ceftizoxime, ceftriaxone, cefuroxime, loracarbef

doripenem, ertapenem, imipenem, meropenem

Penicillin MICs ≤ 2 μg/mL indicate susceptibility to parenteral penicillin,

amoxicillin, amoxicillin-clavulanic acid, cefepime, cefotaxime, ceftriaxone,

and ertapenem.

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b-Streptococcus - 2013

Clarified note for erythromycin for testing and reporting on isolates from pregnant women with severe penicillin allergies

When a Group B Streptococcus is isolated from a pregnant woman

with severe penicillin allergy (high risk for anaphylaxis), erythromycin and clindamycin, (including inducible clindamycin resistance) should

be tested, and only clindamycin should be reported.

Clarified that susceptibility testing of β-hemolytic streptococci need not be performed routinely.

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Inducible clindamycin resistance -

Streptococcus: - 2013

b-Streptococcus: If performing susceptibility testing on these organisms, you should

include inducible-clindamycin resistance testing.

S.pneumoniae:

The clinical significance of this mechanism of clindamycin resistance

is not known for S.pneumoniae, but inducible clindamycin resistance can be detected using the D-zone test and will now be included in

the 2013 CLSI documents.

If testing S.pneumoniae to clindamycin and the isolate is clindamycin-S, a test for inducible clindamycin resistance should be

performed.

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New antibiotics

Doripenem

Ceftaroline

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Doripenem (Doribax)

A broad spectrum injectable antibiotic

A b-lactam drug

Belongs to the carbapenem group (imipenem, ertapenem, meropenem)

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Doripenem

Complicated Intra-Abdominal Infections

Indicated as a single agent for the treatment of complicated intra-

abdominal infections caused by Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Bacteroides caccae, Bacteroides fragilis, Bacteroides thetaiotaomicron, Bacteroides uniformis, Bacteroides vulgatus, Streptococcus intermedius, Streptococcus constellatus and Peptostreptococcus micros.

Complicated Urinary Tract Infections, Including Pyelonephritis

Indicated as a single agent for the treatment of complicated urinary tract infections, including pyelonephritis caused by Escherichia coli including

cases with concurrent bacteremia, Klebsiella pneumoniae, Proteus mirabilis, Pseudomonas aeruginosa, and Acinetobacter baumannii.

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Doripenem

Exerts its bactericidal activity by inhibiting bacterial cell wall biosynthesis.

Inactivates multiple essential penicillin-binding proteins (PBPs) resulting in inhibition of cell wall synthesis with subsequent cell death.

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Doripenem

Bacterial resistance mechanisms that affect doripenem include: Inactivation by carbapenem-hydrolyzing enzymes

KPC, NDM-1, etc.

Mutant or acquired PBPs

Decreased outer membrane permeability

Active efflux

Doripenem is stable to hydrolysis by most b-

lactamases, including penicillinases and cephalosporinases produced by GP &GN bacteria

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Doripenem (Gram positive’s)

Staphylococcus aureus (MSSA only)

Streptococcus agalactiae

Streptococcus pyogenes

Streptococcus Viridans group

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S (mg/ml) I (mg/ml) R (mg/ml)

Streptococcus Viridans group (O) < 1.0

- -

b-Streptococcus (O) < 0.12 - -

S.pneumoniae (O)

< 1.0 - -

S.aureus*

- - -

Doripenem (Gram positive’s)

*Remember: Only penicillin, oxacillin (cefoxitin), ceftaroline for staph with the b-lactams in 2013

No disk diffusion criteria

Ceftaroline (Teflaro)

Acute Bacterial Skin and Skin Structure Infections

Indicated for the treatment of acute bacterial skin and skin structure

infections caused by susceptible isolates of Staphylococcus aureus (including methicillin-susceptible and -resistant isolates), Streptococcus pyogenes, S.agalactiae, E.coli, K.pneumoniae, and K.oxytoca.

Community-Acquired Bacterial Pneumonia

Indicated for the treatment of community-acquired bacterial pneumonia

caused by susceptible isolates of the following microorganisms:

Streptococcus pneumoniae, Staphylococcus aureus (MSSA only), Haemophilus influenzae, Klebsiella pneumoniae, K.oxytoca, and E.coli.

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Ceftaroline

Ceftaroline is a cephalosporin with in vitro activity against GP and GN bacteria.

Bactericidal action is mediated through binding to essential penicillin-binding proteins (PBPs).

Bactericidal against S. aureus due to its affinity for PBP2a and against Streptococcus pneumoniae due to its affinity for PBP2x.

Ceftaroline is not active against Gram negative bacteria which produce ESBLs or carbapenemases.

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Ceftaroline

Staphylococcus aureus (MSSA & MRSA)

Streptococcus pyogenes

Streptococcus agalactiae


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Ceftaroline

S (mg/ml) - mm

I (mg/ml) - mm

R (mg/ml) - mm

S.aureus (B)

< 1 / > 24 2 / 21-23 > 4 / < 20

b-Streptococcus (C)

< 0.5 / > 26 - -

S.pneumoniae (nonmeningitis) (C)

< 0. 5 / > 26 - -

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NEW AST QC Guidance

Table 3C. Disk Diffusion: Reference Guide to QC Frequency

Conversion from Daily to Weekly QC

Routine QC is performed each day the test is performed unless an alternative quality control plan has been established.

CLSI document M02-A11 Section 15.7 describes a QC plan using a 20-30 day protocol that if successfully completed allows a user to convert from daily to weekly quality control.

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NEW AST QC: 3x5 (15) Plan

A new QC plan using a two-phase, 15 replicate (3 X 5 day) plan is described as follows:

15 replicate (3 X 5 day) plan

Test three replicates using individual inoculum preparations of the appropriate QC strains for 5 consecutive test days to perform the 15 replicate (3 x 5 day) plan.

Each QC strain tested is evaluated separately according to the acceptance criteria and recommended action described below (e.g., pass, test another 3 replicates for 5 days, fail).

Upon successful completion of the QC plan, the laboratory can convert from daily to weekly QC testing.

If unsuccessful investigate, take corrective action as appropriate and continue daily QC testing.

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NEW AST QC 3x5 (15)

Table 3C*

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Number out of range

with initial testing

(based on 15

replicates)

Conclusion from

initial testing

Number out of range

after repeat testing

(based on all 30

replicates)

Conclusion after

repeat testing

0-1

QC plan successful.

Convert to weekly QC

testing.

NA

NA

2-3

Test another 3 replicates

for 5 days.

2-3

QC plan successful. Can

convert to weekly

testing.

4 or greater

QC plan fails. Investigate

and take corrective

action as appropriate.

Continue QC each test

day.

4 or greater

QC plan fails. Investigate

and take corrective

action as appropriate.

Continue QC each test

day.

*Assess each QC strain individually

NEW AST QC 3x5 (15)

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Test 3 replicated of each QC strain

for 5 days using individually

prepared inoculum

Fail.

Continue to

include QC

each test day.

Take

corrective

action. Test another 3

replicates for 5

days

Pass. Convert to

weekly QC.

Pass. Convert

to weekly QC.

0-1 of 15 out

of range?

2-3 of 15 out

of range?

> 4 of 15 out

of range?

2-3 of 30 out

of range?

> 4 of 30 out

of range?


Statistician’s comments:

3x5 Plan

Similar to manufactured product releases

‘Go’ or ‘No-Go’ based on mathematical considerations

Two-Stage sampling plan:

May be completed in first stage or proceed to a second stage

Two new plans were considered: 0-1 error allowed in first stage of Plan 1

0 errors allowed in first stage of Plan 2

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Statistician’s comments

Out-of-control results could be due to either systemic or random errors

Systemic errors = likely to get >2 outliers out of 15 results

Random (allowable) errors = very high probability of getting 1 outlier of 15 results due to random error

Plan 1: 0-1 errors allowed: Deemed likely to pick up systematic errors (>2/15)

Plan 2: 0 errors allowed:

Deemed likely to be problematic and unlikely to improve

quality of results (no allowance for random errors @ <1/15) 59

NEW AST QC 3x5 (15)

3x5 Replicate or 20/30 day QC testing.

In addition, this testing is required for the following modifications of existing antimicrobial susceptibility test system:

Addition of new antimicrobial agent to existing system

Convert inoculum preparation/standardization to a method that depends on user technique

Change method of measuring zones

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QC Testing Frequency:

Screening Tests

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QC Strain Current

Positive (resistant) Daily; convert to weekly after 20-30 days

Negative (susceptible) Daily; convert to weekly after 20-30 days

QC Recommendations: ‘Routine’

Test negative (susceptible) QC strain:

With each new lot/shipment of testing materials (eg, disks, or agar plates used for

agar dilution, or single wells or tubes used with broth dilution methods)

Weekly if the screening test is performed at least once a week and criteria for

converting from daily to weekly QC testing have been met (see Section 15.7.2.1 in

M02 or Section 16.7.2.1 in M07)

Daily if the screening test is performed less than once per week and/or if criteria

for converting from daily to weekly QC testing have not been met (see bullet

above).

‘Lot/shipment’

Test positive (resistant) QC strain at minimum of at least once with each new lot/shipment of testing materials

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NEW QC Testing Frequency:

Screening Tests*

NEW QC Testing Frequency:

Screening Tests*

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QC Strain Current New 2013

Positive (resistant) Daily; convert to weekly after 20-30 days

Each new batch/lot/shipment of testing materials

Negative (susceptible) Daily; convert to weekly after 20-30 days

Daily; convert to weekly after 20-30 days

*Applies to disks, or agar plates used for agar dilution (e.g., VRE screen plate),

or single wells or tubes used with broth dilution methods (inducible clindamycin resistance).

Intrinsic Resistance Table

Intrinsic Resistance (Appendix B):

Split out to four appendixes as follows:

B.1 Enterobacteriaceae

Deleted 'R' for Citrobacter koseri with amoxicillin-clavulanate and ampicillin-sulbactam

P. mirabilis – clarified that there is no intrinsic resistance to penicillin and

cephalosporins

Added imipenem with note that Proteus species, Providencia species and Morganella species may have elevated MICs by mechanisms other than by production of carbapenemases

Added information that Enterobacteriaceae are also intrinsically resistant to clindamycin, daptomycin, fusidic acid, glycopeptides (vancomycin, teicoplanin),

linezolid, macrolides (erythromycin, clarithromycin, azithromycin), quinupristin-dalfopristin, and rifampin.

New Appendix B.2 Other Non-Enterobacteriaceae

New Appendix B.3 Staphylococci

New Appendix B.4 Enterococcus spp. 64

Intrinsic Resistance Tables –

Staphylococcus (Appendix B)

Organism / Drug Novobiocin Fosfomycin Fusidic Acid

S.aureus/S.lugdunensis There is no intrinsic resistance in these species.

S.epidermidis There is no intrinsic resistance in this species.

S.haemolyticus There is no intrinsic resistance in this species.

S.saprophyticus R R R

S.capitis R

S.cohnii R

S.xylosus R

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Note 1: Gram-positive bacteria are also intrinsically resistant

to aztreonam, polymyxin B/colistin and naladixic acid.

Organism/drug Cephalo-sporins

Vanco-mycin

Teico-planin

Amino-glycosides

Clinda-mycin

Q/D Trimetho-

prim SXT

Fusidic acid

E.faecalis R* R* R* R R* R R

E.faecium R* R* R* R* R R

E.gallinarum/casseliflavus

R* R R* R* R R* R R

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Intrinsic Resistance Tables –

Enterococcus (Appendix B)

*Warning: For Enterococcus spp., cephalosporins, aminoglycosides (except for

high-level resistance screening), clindamycin, and SXT may appear

active in vivo, but are not effective clinically and should not be reported

as susceptible.

NOTE 1: Gram-positive bacteria are also intrinsically resistant

to aztreonam, polymyxin B/colistin and naladixic acid.

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Summary

CLSI updates AST tables (M100) each January.

CLSI updates documents that describe how to perform reference disk diffusion (M02) and reference MIC (M07) tests every 3 years.


Information listed in boldface type is new or modified since the previous edition of M100.


Minutes of CLSI AST Subcommittee meetings and other materials are available at www.clsi.org.

67 68

Case A

32 year old pregnant woman had a vaginal-rectal specimen sent for GBS culture.

The culture was positive and results were sent to the doctor.

Two days later the doctor’s office calls and requests suceptibility testing because the patient is very allergic to penicillin and the doctor needs the results for a non b-lactam antibiotic for this patient.

You subculture the isolate for susceptibility testing.

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Case A

When testing GBS from a prenatal screen culture, the most important drugs to test and report are?

Drugs to Test (and why):

Drugs to Report (and why):

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Case B

You want to implement a new Staphylococcus panel with ceftraoline (not previously tested in any panel) on your AST system. What will you do? i) Test QC strains on new panel concurrently with patient

isolates for 20-30 days and then go to weekly testing

ii) Test QC strains on new panel before testing patient isolates in the 3x5 replicate plan and then go to weekly testing

iii) Test 10 clinical isolates on new panel and compare ceftaroline results to a reference methods before testing

patients isolates

iv) Something else?

71

Case C

SPECIMEN: Joint Fluid

DIAGNOSIS: Septic Arthritis

ORGANISM: Staphylococcus aureus

MIC (mg/ml)

clindamycin < 0.5 “S”

erythromycin < 0.5 “S”

oxacillin < 0.5 “S”

penicillin “R”

vancomycin < 0.5 “S” 72

http://www.clsi.org/

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Case C

SPECIMEN: Joint Fluid

DIAGNOSIS: Septic Arthritis


MIC (mg/ml)

clindamycin < 0.5 “S”

erythromycin < 0.5 “S”


penicillin “R”

vancomycin < 0.5 “S” 73

Physician calls with

an additional

request…

Case C

Physician calls and asks that ceftriaxone (not on your panel) be tested. What do you do?

74

Case D

SPECIMEN: Blood culture

DIAGNOSIS: Endocarditis


MIC (mg/ml)

clindamycin 8 “R”

erythromycin 16 “R”


vancomycin < 0.5 “S”

75

Case D

SPECIMEN: Blood culture

DIAGNOSIS: Endocarditis


MIC (mg/ml)

clindamycin 8 “R”

erythromycin 16 “R”


vancomycin < 0.5 “S”

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Physician calls with

an additional

request…

Case D

The physician would like to treat this patient with penicillin as it will be a long and protracted course of therapy for this patient.

They notice that penicillin is not resulted on the patient’s report.

What do you tell the physician about the penicillin result on this patient’s isolate?

What further steps do you take regarding this request?

77

Case E

25 y/o woman with acute cystitis.

UR culture grows >100,000 Staphylococcus species

The physician wants additional identification and AST done.

What laboratory tests do you do next?

What do you tell the physician?

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Case F

Young boy 3 y/o present with pneumonia.

The suctioned sputum grows out the pathogen: Streptococcus penumoniae.

You do AST and report out…… … …

Doc wants to use clindamycin for this patient.

What antibiotics do you test (and how do you test) and how do you report the susceptibility

results? 79

Case G

Patient develops pain and swelling in the abdomen.

Ascetic fluid is collected and sent for culture.

The specimen shows many polymorphonuclear cells on initial GS along with moderate GPC in chains.

The culture grows a pure culture of 3+ Streptococcus anginosus group.

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Case G

You report out your normal AST of the following for this organism:

pencillin (R), ceftriaxone (S), vancomycin (S),

clindamycin (S)

Is there anything suspect about the above susceptibility

results?

The physician calls and asks for doripenem to be tested. You do have doripenem disks and it is on your streptococci microtiter panels. What do you do?

81

Case H

78 year old man with signs of pneumonia is admitted through the Emergency Department.

Sputum is collected and grows many Streptococcus pneumoniae with a few oral flora (GS was significant for many PMNS and GPC in short chains).

82

Case H

The doctor calls and ask for a ‘fluoroquinolone to be tested’ other than levofloxacin (which is in your current pneumo panel).

Here is your antibiotic panel results: Penicillin (nonmeningitis) – S

Penicillin (oral) – S

Erythromycin – R

SXT – S

Levofloxacin - S 83

Case H

What antibiotics do you test?

What do you report to the physician?

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8/28/2012


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Today’s Review: 2012-2013 changes



b-Streptococcus species

Enterococcus species

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CLSI Review


Information listed in boldface type is new or modified since the previous edition of M100 document.


Go to CLSI website for up-to-date information.

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CLSI

Watch for the 2013 M100 document!

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Thank you for attending !

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Update on the 2012-2013 CLSI Standards for Antimicrobial ... · 8/28/2012 jhindler CLSI M100-S22...

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