Gram negative rods blood culture11/21/2023 A diagnostic algorithm for positive blood culture broths that incorporates gram staining and MALDI-TOF MS should identify the majority of pathogens, particularly to genus level.īloodstream infections (BSIs) are a significant cause of morbidity and mortality in hospitals. Positive predictive values for the direct identification of both gram-positive and gram-negative bacteria from monomicrobial blood culture broths to genus level were 100%. Five blood cultures were misidentified, but at species level only including four monomicrobial blood cultures with Streptococcus oralis/ mitis that were misidentified as Streptococcus pneumoniae. Significantly more gram-negative organisms were identified compared to gram-positive organisms at species level (p<0.0001). Spectral scores <1.700 (no identification) were obtained in 128/507 (25.2%) positive blood culture broths, including 31.6% and 32.3% of gram-positive and polymicrobial blood cultures, respectively. Five hundred and seven positive blood culture broths were prospectively examined, of which 379 (74.8% 358 monomicrobial, 21 polymicrobial) were identified by MALDI-TOF MS 195 (100%) and 132 (67.7%) of 195 gram-positive and 163 (100%) and 149 (91.4%) of 163 gram-negative organisms from monomicrobial blood cultures were correctly identified to genus and species level, respectively. We evaluate for the first time, the performance of the MALDI Sepsityper™ Kit and MS for the identification of bacteria compared to standard phenotypic methods using the manufacturer's specified bacterial identification criteria (spectral scores ≥1.700–1.999 and ≥2.000 indicated identification to genus and species level, respectively). Improved antibiotic stewardship and strict infection control measures especially hand washing need to be implemented to prevent emergence and spread of multidrug resistant NFGNB in health care settings.Matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS) is a novel method for the direct identification of bacteria from blood culture broths. Conclusions: This study underlines the need to identify NFGNB in tertiary care hospitals and to monitor their susceptibility pattern to guide the clinician for better care and management of patients. The most effective drugs were colistin and tigecycline. Most of the non -fermenters were multi drug resistant showing a high level of antibiotic resistance to most of the first- and second-line drugs. (95) followed by Pseudomonas aeruginosa (11), Burkholderia cepacia (09) Sternotrophomonas maltophilia (03) and Sphingomonas sp. Results: A total of 120 NFGNB were identified out of which the most common non-fermenters isolated were Acinetobacter sp. Blood culture was done by automated blood culture system, (BacT/Alert) and identification and antibiotic susceptibility of non-fermenting gram negative bacilli was done by VITEK2 Compact System. All samples were processed according to standard microbiological procedures. Methods: A total of 3016 blood samples were received in the Department of Microbiology during the study period. The aim of this study was to assess frequency and antibiotic susceptibility pattern of non-fermenting gram-negative rods isolated from blood culture of patients. High intrinsic resistance of NFGNB to antimicrobial compounds makes the treatment of BSIs caused by them difficult and expensive. ABSTRACT Background: Non-fermenting Gram-negative bacilli (NFGNB) are emerging as important causes of blood stream infections (BSI) and they are a major cause of morbidity and mortality worldwide.
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