Evaluation of a direct blood culture disk diffusion antimicrobial susceptibility test

Doern, G V; Scott, David; Rashad, Abdel L.; Kim, K S

doi:10.1128/aac.20.5.696

Cited by 46 publications

(43 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Susceptibility testing for the 11 antibiotics had an overall increase in accuracy with a higher percentage in MIC agreement than this in the previous study on pure isolates. Direct susceptibility testing using the disk method was found to be useful, providing results up to 24 h sooner (2,12). However, the reliability of the direct disk susceptibility assay may be difficult to establish due to the fact that the techniques have not been well standardized (4,11).…”

Section: Discussionmentioning

confidence: 99%

Evaluation of the VITEK 2 System for Rapid Direct Identification and Susceptibility Testing of Gram-Negative Bacilli from Positive Blood Cultures

2003

View full text Add to dashboard Cite

This study explores the possibility of combining the BacT/Alert Microbial Detection System with the VITEK 2 system to achieve rapid bacterial identification and susceptibility testing. Direct inoculation of bacterial suspension to the VITEK 2 ID-GNB card and AST-NO09 card was made by differential centrifugation of blood cultures of organisms with gram-negative enteric bacillus-like morphology. A total of 118 strains were investigated; of these, 97 (82.2%) strains were correctly identified to the species level and 21 (17.8%) strains were not identified; by comparing the results with those of the reference method of API identification systems using a pure culture, it was found that no strain had been misidentified. Among the 21 strains with no identification, 13 (61.9%) strains were nonfermenters. The direct-identification reporting time of VITEK 2 was 3.3 h. Direct testing of susceptibility to 11 antibiotics, i.e., amikacin, cefepime, ceftazidime, ciprofloxacin, gentamicin, imipenem, meropenem, netilmicin, piperacillin, piperacillin-tazobactam, and tobramycin, was also performed by using the broth microdilution (MB) method according to the NCCLS guidelines as a reference. After comparing the MICs of the VITEK 2 system with those obtained by the MB method within ؎twofold dilution, it was determined that the 1,067 organism-antibiotic combinations had an overall correct rate of 97.6% (1,041 combinations). The rates of susceptibility to the 11 antibiotics ranged from 88.7 to 100%, respectively. Only two (0.2%) and four (0.4%) combinations of the susceptibility tests gave very major errors (i.e., reported as sensitive by the VITEK 2 system but shown to be resistant by the MB method) and major errors (i.e., reported as resistant by the VITEK 2 system but shown to be sensitive by the MB method), respectively. The reporting time for the direct testing of susceptibility against the 11 antibiotics for 97 blood culture isolates by the VITEK 2 system ranged from 3.3 to 17.5 h. Compared with conventional methods that require 1 or 2 days, this method can make same-day reporting possible and thus permit better patient management.The detection of bloodstream infections is one of the most important tasks performed by the clinical microbiology laboratory. Rapid bacterial identification and susceptibility testing not only improve patient therapy and outcome, but also reduce costs (1,17,18). Both automated blood culture systems and automated systems for identification and susceptibility testing of bacteria have been on the market for a number of years (8). The VITEK 2 system (BioMérieux) is a new automated bacterial identification and susceptibility testing system that uses fluorescence-based technology. Previous studies showed that this system could give reliable identification and susceptibility results with pure bacterial cultures (5, 6, 10). This study explores the possibility of combining these systems to achieve rapid identification and susceptibility testing by direct inoculation from positive blood cultures. MATERIALS AND ME...

show abstract

Section: Discussionmentioning

confidence: 99%

Evaluation of the VITEK 2 System for Rapid Direct Identification and Susceptibility Testing of Gram-Negative Bacilli from Positive Blood Cultures

2003

View full text Add to dashboard Cite

show abstract

“…Due to the success of the Etest in fungal susceptibility testing and in light of its success in direct antibacterial susceptibility testing (9,15,18), we felt that a similar procedure for the direct antifungal testing of fungi could be developed. The major question at the outset appeared to be whether fungi grew to a level in blood culture medium significant enough to serve as a direct inoculum for the test.…”

Section: Discussionmentioning

confidence: 99%

“…Based on the interpretive breakpoints defined by NCCLS for flucytosine, fluconazole, and itraconazole (20), the MICs obtained by the different methods were translated into susceptibility categories (resistant, intermediate/susceptible-dose dependent, and susceptible). The results of interpretive susceptibilities obtained from DET (or ET) were compared with those obtained from the MD method, and discrepancies were classified as very major (false susceptibility by DET or ET), major (false resistance by DET or ET), or minor (9). A minor error was defined as any change involving a dose dependently or intermediately susceptible result.…”

Section: Methodsmentioning

confidence: 99%

Evaluation of Etest for Direct Antifungal Susceptibility Testing of Yeasts in Positive Blood Cultures

Chang¹,

Chang²,

Chan³

et al. 2001

J Clin Microbiol

View full text Add to dashboard Cite

The performance of the Etest (AB BIODISK, Solna, Sweden) for direct antifungal susceptibility testing of yeasts in positive blood cultures was compared with that of the macrodilution method for determining the MICs of five antifungal agents. Culture broths with blood from bottles positive for yeasts were inoculated directly onto plates for susceptibility testing with the Etest, and the MICs were read after 24 and 48 h of incubation. A total of 141 positive blood cultures (72 cultures of Candida albicans, 31 of Candida tropicalis, 14 of Candida glabrata, 11 of Candida parapsilosis, 3 of Candida krusei, and 3 of Cryptococcus neoformans, 4 miscellaneous yeast species, and 3 mixed cultures) were tested, and the rates of MIC agreement (؎1 log 2 dilution) between the direct Etest (at 24 and 48 h, respectively) and macrodilution methods were as follows: amphotericin B, 81.8 and 93.5%; flucytosine, 84.8 and 87.7%; fluconazole, 89.4 and 85.5%; itraconazole, 69.7 and 63.8%; ketoconazole, 87.9 and 79.0%. By a large-sample t test, the difference in log 2 dilution between the direct Etest and the macrodilution method was found to be small (P < 0.05). The lone exceptions were ketoconazole at 48 h of incubation and itraconazole at both 24 and 48 h of incubation (P > 0.05). By Tukey's multiple comparisons, the difference between the direct Etest (48 h) and reference methods among different species was found to be less than 1 log 2 dilution. When the MICs were translated into interpretive susceptibility, the minor errors caused by the direct Etest (at 24 and 48 h, respectively) were as follows: flucytosine, 2.3 and 1.4%; fluconazole, 3.0 and 3.6%; itraconazole, 21.2 and 21.3%. Itraconazole also produced an additional 3.0 and 3.6% major errors as determined by the direct Etest at 24 and 48 h, respectively. It was concluded that, except for itraconazole, the Etest method was feasible for direct susceptibility testing of blood cultures positive for yeasts. The method is simple, and the results could be read between 24 and 48 h after direct inoculation, whenever the inhibition zones were discernible.

show abstract

“…However, the correlations between the disc diffusion method and broth dilution method for 10 antibiotics against 17 oxytetracycline-resistant isolates were 97.65 % in agreement between methods and 2.35 % showing major error. Major errors between methods using fluoroquinolones such as ciprofloxacin and ofloxacin against Enterobacteriaceae (Steward et al, 1999), and clindamycin, the second-generation lincomycin against staphylococci and micrococci (Doern et al, 1981), have been reported previously. In the present study, the finding of increasing incidence of GBS isolates resistant to tetracycline with high MIC and MBC values emphasizes the need to …”

mentioning

confidence: 99%

Serotype distribution and antimicrobial susceptibilities of Streptococcus agalactiae isolated from infected cultured tilapia (Oreochromis niloticus) in Thailand: Nine-year perspective

Dangwetngam

Suanyuk

Kong

et al. 2016

Journal of Medical Microbiology

View full text Add to dashboard Cite

Streptococcus agalactiae (group B Streptococcus, GBS) infection remains a major problem associated with high mortality of cultured tilapia worldwide. The present study reports the serotype distribution and antimicrobial susceptibilities of GBS isolated from infected tilapia cultured in Thailand. One hundred and forty-four GBS isolates were identified by biochemical, serological and molecular analyses. Of these 144 GBS isolates, 126 were serotype Ia and 18 were serotype III. Antimicrobial susceptibilities of the 144 GBS isolates were determined by the disc diffusion method. Most GBS isolates were susceptible to lincomycin, norfloxacin, oxytetracycline, ampicillin, erythromycin and chloramphenicol, but resistant to oxolinic acid, gentamicin, sulfamethoxazole and trimethoprim. However, 17 isolates displayed an oxytetracycline-resistant phenotype and harboured the tet(M) gene. The broth microdilution method was used to determine the minimal inhibitory concentrations (MICs) of 17 oxytetracycline-resistant GBS isolates, and then minimal bactericidal concentrations (MBCs) of these isolates were evaluated. Oxytetracyline-resistant isolates were found to be susceptible to ampicillin, lincomycin, norfloxacin, erythromycin and chloramphenicol, with the MIC and MBC ranging from j0.125 to 0.5 mg ml 21 and j0.125 to 2 mg ml 21 , respectively. Moreover, all 17 oxytetracycline-resistant isolates demonstrated resistance to trimethoprim, oxolinic acid, gentamicin, sulfamethoxazole and oxytetracycline, with the MIC and MBC ranging from 16 to $128 mg ml 21 and $128 mg ml 21, respectively. These findings are useful information for antibiotic usage in fish aquaculture.

show abstract

Evaluation of a direct blood culture disk diffusion antimicrobial susceptibility test

Cited by 46 publications

References 2 publications

Evaluation of the VITEK 2 System for Rapid Direct Identification and Susceptibility Testing of Gram-Negative Bacilli from Positive Blood Cultures

Evaluation of the VITEK 2 System for Rapid Direct Identification and Susceptibility Testing of Gram-Negative Bacilli from Positive Blood Cultures

Evaluation of Etest for Direct Antifungal Susceptibility Testing of Yeasts in Positive Blood Cultures

Serotype distribution and antimicrobial susceptibilities of Streptococcus agalactiae isolated from infected cultured tilapia (Oreochromis niloticus) in Thailand: Nine-year perspective

Contact Info

Product

Resources

About