AST - Stool Cultures
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Contact us to obtain critiques older than 5 years.
Scroll down to find Critique number of older challenges and a brief description.
Some older archived critiques are included in this list, but CMPT advises visitors to also consult recent literature.
Disclaimer: Please consult most recent CLSI guidelines and SOPs for your laboratory. See CLSI information page.
YEAR CRITIQUE SUMMARY
2010 M101-3 Shigella sonnei : For ampicillin susceptibility, the MIC of the organism was found to be 8mg/L by most laboratories.  This value is at the upper end of the susceptible range and, not surprisingly, some laboratories had results of 16mg/L (intermediate by CLSI standards).  If we accept the MIC +/- 1 dilution, which is the usually accepted range of error with susceptibility testing, then MICs of 4, 8, and 16 are to be expected and "I" result is not unreasonable in that circumstance (and it is not an uncommon practice for labs to report I as R).Laboratories that obtained a MIC of 8mg/L should have reported their results as “S” and not “R”; this is considered a major error.
Laboratories that use standards other than the CLSI standards (e.g. EUCAST) should indicate that a different interpretive standard is being used.
2009 M093–3

Plesiomonas shigelloides. The course of an uncomplicated diarrhea is self-limiting in 85% of the patients. Patients always respond to symptomatic treatment, and antimicrobial therapy is rarely needed.
2009 M084-3

In this scenario (stool from a 23-year old female hiker returning from South-East Asia), due to the co-infection with Shigella species, which are often multi-drug resistant, and because Salmonella Enteritidis has been documented as drug resistant, the approach to confirm and report out antimicrobial susceptibility results for each isolate is warranted to guide therapy.

2006, 2001, 1997 M063-2 , M012-3,
M73-3		 Yersinia enterocolitica Testing was not requested for this isolate in this challenge (M063-2). Gastrointestinal infections with Y. enterocolitica are usually self-limited and do not need specific antibiotic therapy. Treatment is recommended for enteritis in immunocompromised patients, complicated gastroenteritis, and for extra-intestinal infections. Y. enterocolitica is susceptible to chloramphenicol, aminoglycosides, tetracycline, trimethoprim/sulfamethoxazole (SXT), and third-generation cephalosporins. Chromosomally determined beta-lactamases account for resistance to first-generation cephalosporins, ampicillin, and carbenicillin.
2006, 2003 M061-3, M031-3 Campylobacter coli, Standardized guidelines are being developed for the interpretation of susceptibility tests for Campylobacter species.
Campylobacter jejuni Due to the possibility of emerging resistance in Campylobacter, and the obvious advantages of treatment, laboratories may need to monitor the susceptibility pattern of this organism or be prepared to refer isolates for testing.
2005 M052-2 Shigella sonnei Laboratories that reported ampicillin as susceptible and SXT resistant received a grade of 4 for each antimicrobial.
2004 M044-3

Salmonella braenderup (group C1)Uncomplicated gastrointestinal infection caused by Salmonella is self-limiting and should not be treated with antimicrobials because of the risk of development of the carrier state and because treatment does not reliably decrease duration of excetion of Salmonella following infection.

If bacteremia occurs it is important to distinguish between endovascular, which requires a longer treatment course, from other infection. Endovascular infection may be indicated by high grade bacteremia with greater than 50% of sets of blood cultures drawn from an individual being positive. In cases of infection with susceptible organisms, a fluoroquinolone, cotrimoxazole,
or amoxicillin may be used. In life threatening infection such as bacteremia or suspected focal infection a third-generation cephalosporin with a fluoroquinolone should be used until antimicrobial susceptibility patterns are available.

  M042-3, M023-3 (Vibrio parahaemolyticus), Antimicrobial treatment for acute diarrheal illness is usually not required. If required, supportive measures for dehydration are similar to those for V. cholerae.
(Vibrio fluvialis) See V. vulnificus (wound M073-2)
2003 M032-2 Stool E. coli O157:H7 - Susceptibility testing of E. coli O157 may be performed for epidemiological purposes, but NOT for therapy. For clinical purposes, it is inappropriate to report susceptibilities, and in the future, CMPT grading will reflect this.
2002 M021-3, M74-4 Aeromonas caviae
2001 M014-3, M84-3 Plesiomonas shigelloides