Evaluation of three protocols for direct susceptibility testing for Gram-negative rods from flagged positive blood culture bottles
ABSTRACTBloodstream infections are associated with high mortality, which can be reduced by targeted antibiotic therapy in the early stages of infection. Direct antibiotic susceptibility testing (AST) from flagged positive blood cultures may facilitate the administration of early effective antimicrob...
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| Format: | Article |
| Language: | English |
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American Society for Microbiology
2024-04-01
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| Series: | Microbiology Spectrum |
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| Online Access: | https://journals.asm.org/doi/10.1128/spectrum.03081-23 |
| _version_ | 1797228835974938624 |
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| author | Salman Khan Arghya Das Anwita Mishra Ashima Jain Vidyarthi Mukesh Nandal Himanshu Yadav Shayak Roy Mahipal Singh |
| author_facet | Salman Khan Arghya Das Anwita Mishra Ashima Jain Vidyarthi Mukesh Nandal Himanshu Yadav Shayak Roy Mahipal Singh |
| author_sort | Salman Khan |
| collection | DOAJ |
| description | ABSTRACTBloodstream infections are associated with high mortality, which can be reduced by targeted antibiotic therapy in the early stages of infection. Direct antibiotic susceptibility testing (AST) from flagged positive blood cultures may facilitate the administration of early effective antimicrobials much before the routine AST. This study aimed to evaluate three different direct AST protocols for Gram-negative rods from flagged positive blood culture broths. Blood culture broths showing Gram-negative rods only were subjected to direct AST by Clinical and Laboratory Standards Institute-recommended direct disk diffusion (protocol A). Additionally, automated AST (protocol B) and Kirby-Bauer disk diffusion (protocol C) were performed with standard inoculum prepared from bacterial pellets obtained by centrifuging blood culture broths in serum separator vials. For comparison, conventional AST of isolates from solid media subculture was also performed with Kirby-Bauer disk diffusion (reference standard) and the automated method. Overall, categorical agreements of protocols A, B, and C were 97.6%, 95.7%, and 95.9%, respectively. Among Enterobacterales, minor error, major error, and very major error rates of protocol B were 3.5%, 0.36%, and 0.43%, respectively, whereas minor error, major error, and very major error rates of protocol C were 3.4%, 0.72%, and 0.21%, respectively, and among non-fermenters, protocol B had a minor error rate of 6.5%, and protocol C had a minor error rate of 4.1% and major error rate of 1.9%. All three direct AST protocols demonstrated excellent categorical agreements with the reference method. Performance of protocols B and C between Enterobacterales and non-fermenters was not statistically different.IMPORTANCEBloodstream infections are associated with high mortality that can be reduced by targeted antibiotic therapy in the early stages of infection. Direct antibiotic susceptibility testing (AST) from flagged positive blood cultures may facilitate the administration of early effective antimicrobials much before the routine AST. Clinical and Laboratory Standards Institute-recommended direct AST can be performed with a limited number of antibiotic disks only. On the other hand, using an automated system for direct AST will not only allow effective laboratory workflow with reduced turnaround time but also provide the minimum inhibitory concentration values of tested antibiotics. However, using expensive automated systems for direct AST may not be feasible for resource-limited laboratories. Therefore, in this study, we aimed to evaluate the CLSI-recommended method and two other direct AST protocols (one with an automated system and the other with disk diffusion) for Gram-negative rods from flagged positive blood cultures. |
| first_indexed | 2024-04-24T15:03:01Z |
| format | Article |
| id | doaj.art-49d1839bd58547daa0468d836d674912 |
| institution | Directory Open Access Journal |
| issn | 2165-0497 |
| language | English |
| last_indexed | 2024-04-24T15:03:01Z |
| publishDate | 2024-04-01 |
| publisher | American Society for Microbiology |
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| series | Microbiology Spectrum |
| spelling | doaj.art-49d1839bd58547daa0468d836d6749122024-04-02T14:16:18ZengAmerican Society for MicrobiologyMicrobiology Spectrum2165-04972024-04-0112410.1128/spectrum.03081-23Evaluation of three protocols for direct susceptibility testing for Gram-negative rods from flagged positive blood culture bottlesSalman Khan0Arghya Das1Anwita Mishra2Ashima Jain Vidyarthi3Mukesh Nandal4Himanshu Yadav5Shayak Roy6Mahipal Singh7Department of Microbiology, National Cancer Institute, All India Institute of Medical Sciences (Jhajjar-campus), New Delhi, IndiaDepartment of Microbiology, All India Institute of Medical Sciences, Madurai, IndiaDepartment of Microbiology, Mahamana Pandit Madan Mohan Malviya Cancer Centre and Homi Bhabha Cancer Hospital, Varanasi, IndiaDepartment of Microbiology, National Cancer Institute, All India Institute of Medical Sciences (Jhajjar-campus), New Delhi, IndiaDepartment of Emergency Medicine, National Cancer Institute, All India Institute of Medical Sciences (Jhajjar-campus), New Delhi, IndiaDepartment of Microbiology, National Cancer Institute, All India Institute of Medical Sciences (Jhajjar-campus), New Delhi, IndiaDepartment of Oncoanaesthesia and Palliative Medicine, National Cancer Institute, All India Institute of Medical Sciences (Jhajjar-campus), New Delhi, IndiaDepartment of Microbiology, National Cancer Institute, All India Institute of Medical Sciences (Jhajjar-campus), New Delhi, IndiaABSTRACTBloodstream infections are associated with high mortality, which can be reduced by targeted antibiotic therapy in the early stages of infection. Direct antibiotic susceptibility testing (AST) from flagged positive blood cultures may facilitate the administration of early effective antimicrobials much before the routine AST. This study aimed to evaluate three different direct AST protocols for Gram-negative rods from flagged positive blood culture broths. Blood culture broths showing Gram-negative rods only were subjected to direct AST by Clinical and Laboratory Standards Institute-recommended direct disk diffusion (protocol A). Additionally, automated AST (protocol B) and Kirby-Bauer disk diffusion (protocol C) were performed with standard inoculum prepared from bacterial pellets obtained by centrifuging blood culture broths in serum separator vials. For comparison, conventional AST of isolates from solid media subculture was also performed with Kirby-Bauer disk diffusion (reference standard) and the automated method. Overall, categorical agreements of protocols A, B, and C were 97.6%, 95.7%, and 95.9%, respectively. Among Enterobacterales, minor error, major error, and very major error rates of protocol B were 3.5%, 0.36%, and 0.43%, respectively, whereas minor error, major error, and very major error rates of protocol C were 3.4%, 0.72%, and 0.21%, respectively, and among non-fermenters, protocol B had a minor error rate of 6.5%, and protocol C had a minor error rate of 4.1% and major error rate of 1.9%. All three direct AST protocols demonstrated excellent categorical agreements with the reference method. Performance of protocols B and C between Enterobacterales and non-fermenters was not statistically different.IMPORTANCEBloodstream infections are associated with high mortality that can be reduced by targeted antibiotic therapy in the early stages of infection. Direct antibiotic susceptibility testing (AST) from flagged positive blood cultures may facilitate the administration of early effective antimicrobials much before the routine AST. Clinical and Laboratory Standards Institute-recommended direct AST can be performed with a limited number of antibiotic disks only. On the other hand, using an automated system for direct AST will not only allow effective laboratory workflow with reduced turnaround time but also provide the minimum inhibitory concentration values of tested antibiotics. However, using expensive automated systems for direct AST may not be feasible for resource-limited laboratories. Therefore, in this study, we aimed to evaluate the CLSI-recommended method and two other direct AST protocols (one with an automated system and the other with disk diffusion) for Gram-negative rods from flagged positive blood cultures.https://journals.asm.org/doi/10.1128/spectrum.03081-23directantimicrobialsusceptibilityblood culturecategorical agreementdisk diffusion |
| spellingShingle | Salman Khan Arghya Das Anwita Mishra Ashima Jain Vidyarthi Mukesh Nandal Himanshu Yadav Shayak Roy Mahipal Singh Evaluation of three protocols for direct susceptibility testing for Gram-negative rods from flagged positive blood culture bottles Microbiology Spectrum direct antimicrobial susceptibility blood culture categorical agreement disk diffusion |
| title | Evaluation of three protocols for direct susceptibility testing for Gram-negative rods from flagged positive blood culture bottles |
| title_full | Evaluation of three protocols for direct susceptibility testing for Gram-negative rods from flagged positive blood culture bottles |
| title_fullStr | Evaluation of three protocols for direct susceptibility testing for Gram-negative rods from flagged positive blood culture bottles |
| title_full_unstemmed | Evaluation of three protocols for direct susceptibility testing for Gram-negative rods from flagged positive blood culture bottles |
| title_short | Evaluation of three protocols for direct susceptibility testing for Gram-negative rods from flagged positive blood culture bottles |
| title_sort | evaluation of three protocols for direct susceptibility testing for gram negative rods from flagged positive blood culture bottles |
| topic | direct antimicrobial susceptibility blood culture categorical agreement disk diffusion |
| url | https://journals.asm.org/doi/10.1128/spectrum.03081-23 |
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