T.E.S.T. began in 2004. Consecutive isolates are collected from patients with a documented infection, and only isolates that are determined by the center to be clinically significant (using local criteria) are included. Only one isolate per patient is permitted. All body sites are considered acceptable clinical sources; however, no more than 25% of isolates for any center can come from urine cultures.

Isolates are identified by the participating laboratory to species level. Species included in the study are listed below.

Organism collection, transport, and confirmation of organism identity are carried out by a central laboratory (Laboratories International for Microbiology Studies, a division of International Health Management Associates, Inc., Schaumburg, IL, USA).

Antimicrobial Susceptibility Testing

All minimum inhibitory concentrations (MICs) are determined locally, and the information is returned to the central laboratory using an OptiScan Data Collection Form, part of a proprietary optical character recognition system, for inclusion in the centralized database.

MICs are determined according to the broth microdilution methodology of the Clinical and Laboratory Standards Institute (CLSI, formerly National Committee for Clinical Laboratory Standards, NCCLS 2003), using gram-positive and -negative broth microdilution panels (MicroScan, Dade Behring, Sacramento, CA, USA). All determinations are carried out using cation-adjusted Mueller-Hinton broth with the exception of Streptococcus spp., which are cultured in Mueller-Hinton broth supplemented with lysed horse blood and Haemophilus influenzae, which is cultured in Haemophilus test medium. Panels are incubated from 16-20 h in ambient air at 35ºC. In the case of Streptococcus spp. and Haemophilus influenzae, panels are incubated under the same conditions for 20-24 h. For Enterococcus spp. in the presence of vancomycin and Staphylococcus aureus in the presence of vancomycin or oxacillin, panels are incubated for 24 h.

The antimicrobial agents tested and the testing ranges are shown in Table 1. Quality control is carried out by each testing site on each day of testing. The quality control strains are Escherichia coli ATCC 25922, Haemophilus influenzae ATCC 49766 and 49247, Staphylococcus aureus ATCC 29213, Pseudomonas aeruginosa ATCC 27853, Enterococcus faecalis ATCC 29212, and Streptococcus pneumoniae ATCC 49619.

Locations (geographical)

130 centers globally
200 isolates per center per year

Pathogens

60 gram-positive:

15 S. pneumoniae
15 Enterococcus spp. (14 possible species)
20 S. aureus (3: MSSA, MRSA, plain S. aureus)
10 S. agalactiae

135 gram-negative:

15 H. influenzae
15 Acinetobacter spp. (11 possible species)
25 E. coli
25 Enterobacter spp. (15 possible species)
20 P. aeruginosa
10 Serratia spp. (8 possible species)
25 Klebsiella spp. (11 possible species)

Demographics

Outpatients OK for "fastidious" organisms - S. pneumoniae, H. influenzae otherwise; hospital pathogens only

Age
Sex
Specimen Source
Location (Specialty)

Table 1. Antibiotics Tested

Gram-positive

Gram-negative