CLSI 2017, Changes, Modified Carbapenem Inactivation Method, mCIM for enterobacteriaceae, revised Colistin breakpoints, ECV(epidemiological cut off values), Telavancin, Deletion of Norfloxacin, deletion of Gemifloxacin and Cefuroxime(parenteral),

1. CHANGES IN
CLSI 2017
Capt. Mohammed Ashraf Ali
M.D (Microbiology)

2. OUTLINE
A. Definition of Test / Report groups
B. Major deletions in CLSI 2017
C. Summary of antibiotic changes for
Individual bacteria
D. Addition of Supplemental tests
E. Changes in reporting for colistin
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3. A. ANTIBIOTIC TEST/REPORT GROUPS
 Group A: Routine reporting against specific organism
 Group B: Warrants primary testing and selective reporting.
 Group C: Supplemental antimicrobial agents: institutional
endemic/epidemic resistant strains
 Group U (“urine”): antimicrobials for treating UTIs.
 Group O (“other”): clinical indication but are generally not
candidates for routine testing and reporting.
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4.  Table 1A- Antimicrobial Agents :Testing
and Reporting on Nonfastidious
Organisms.
 Table 1B – Fastidious organisms
 Table 1C - Anaerobic Organisms
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5. Moved to
Test
Group C
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6. Deleted
Deleted
Deleted
Deleted
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8. Deleted
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9. Deleted
Deleted
Ciprofloxacin or
levofloxacin or
moxifloxacin
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10. Deleted
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11. B. MAJOR DELETIONS
1. Norfloxacin – Group U drug : Table 1A
2. Cefuroxime (parenteral) and
gemifloxacin from Table 1A, 1B and 1C.
3. Nalidixic acid breakpoints for
Salmonella spp
4. Telavancin disk diffusion breakpoints
for S.aureus.
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12. ORGANISMS IN TABLE 1A
Staphylococcus spp and Enterococcus spp. :
 Norfloxacin – deleted
 Moved ortivancin and telavancin to Test Group C
Enterobacteriaceae (except Salmonella sp) :
 Gemifloxacin, norfloxacin – deleted
 Enoxacin – moved to Test Group C
 Nalidixic acid – Moved to Test group O (Enterobacteriaceae
except Salmonella)
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13. Salmonella spp.
 Nalidixic acid disc diffusion breakpoints deleted for
Salmonella spp.
 Preferred test for assessing fluoroquinolone susceptibility
or resistance is a ciprofloxacin MIC test
 Pefloxacin disk diffusion test – surrogate test to predict
ciprofloxacin susceptibility
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14. Epidemiological Cutoff Values (ECVs)
for Enterobacteriaceae
 not to be used as clinical breakpoints
Antimicrobial
agent
MIC ECV Comments
WT NWT
Colistin ≤ 2 ≥ 4 For use with E. aerogenes, E. cloacae,
E.coli, K. pneumoniae and R. ornitholytica
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15. Pseudomonas aeruginosa
 Deleted colistin disk diffusion breakpoints.
 Deleted polymyxin B disk diffusion breakpoints.
 Moved norfloxacin to Test/Report group O and clarified
reporting.
 Revised colistin MIC breakpoints.
Acinetobacter spp
 No changes
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16. Other Non-Enterobacteriaceae
 Deleted colistin and polymyxin B.
 Deleted urinary tract infection (UTI) restriction for
gatifloxacin, lomefloxacin and ofloxacin.
Staphylococcus spp :
No changes
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17. ORGANISMS IN TABLE 1B
H.Influenzae and H.parainfluenzae :
 Moved ciprofloxacin, levofloxacin and moxifloxacin to
Test Group B.
 Moved trimethoprim-sulfamethoxazole to Test Group C.
 Moved cefuroxime (parenteral) to Test Group C.
 Moved gemifloxacin to Test Group C.
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18. Epidemiological Cutoff Values (ECVs)
for Neisseria gonorrhoeae :
Antimicrobial
agent
MIC ECV Comments
WT NWT
Azithromycin ≤ 1 ≥ 2 For use with N.gonorrhoeae
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19. ORGANISMS IN TABLE 1C
Epidemiological Cutoff Values (ECVs)
for Propionibacterium acnes
Antimicrobial
agent
MIC ECV Comments
WT NWT
Vancomycin ≤ 2 ≥ 4 For use with P.acnes
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20. 4. Changes in reporting for Colistin
 Colistin, Polymyxin B not to be reported in Non-Enterobacteriaceae
In P.aeruginosa,
 Colistin and PB not to be reported by disc diffusion.
 Revised colistin MIC breakpoints
LIPOPEPTIDES
S I R
Colistin (10µg) ≤ 2 --- ≥ 4
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21. E. ADDITIONAL TESTS
modified carbapenem inactivation method (mCIM) for suspected
carbapenemase production : Enterobacteriaceae only
Test mCIM
When to do? For epidemiological, not for routine use
Method Meropenem disk inactivation
Test Reagents and
materials
• TSB (2mL aliquots)
• Meropenem disks (10mcg)
• 1mcL and 10mcL inoculation loops
• Normal saline (3-5mL)
• MHA plates (100mm or 150mm)
• Meropenem susceptible indicator strain E.coli
(ATCC 29522)
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22. Procedure:
1. One loopful (1mcL loop) bacteria + 2mL TSB
2. Vortex 10-15s
3. 10mcg meropenem disk added to it
4. Incubate at 35 ± 2ºC for 4 hrs
5. Simultaneously 0.5McFarland suspension of E.coli
ATCC 25922 prepared in NS.
6. E.coli ATCC inoculated on MHA (lawn culture)
7. Meropenem disk is removed from TSB by 10mL loop
and placed on above MHA plate: Incubate at 35 ± 2ºC
for 18-24hrs
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24. Negative
control
Positive
control
Carbapenemase
producer
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25. Test Interpretation
Carbapenemase positive: Zone size of 6-15mm or
presence of colonies within 16-18mm zone
Carbapenemase negative: Zone size ≥ 19mm
Indeterminate: 16-18mm
Reporting:
Positive to be reported as “Carbapenemase detected”
Control strains
K.pneumoniae ATCC BAA1705 : Carbapenemase positive
K.pneumoniae ATCC BAA1706 : Negative
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