Molecular technique for precise antibiotics administration in patients with cancer.

Abstract

e18749 Background: Infectious diseases are the second most common cause of mortality in oncology patients. Multiple hospital admissions and previous exposure to antibiotics are risk factors for infection with microorganisms having antibiotic resistance gene in these patients.Molecular technique helps in targeted antibiotic administration at the earliest. Methods: This was a retrospective observational study over a period of one year from November 2021 to October 2022 in Tata Memorial Hospital, Mumbai, on oncology patients with blood stream infection (BSI) whose blood sample underwent film array assay. The BioFire Blood culture Identification 2 Panel (BCID2) which identifies Imipenemases (IMP), Klebsiella pneumoniae carbapenemases (KPC), New Delhi metallo beta-lactamases (NDM), oxacillinase-48 like (OXA-48), Verona integron-encoded metallo beta-lactamase (VIM), CTX M and methicillin resistance gene like mec A/C was used. BSI was categorised according to the resistance gene and recommended antibiotics of choice as per the Infectious Disease Society of America (IDSA). CTX-M - Carbapenem  OXA-48 like/ KPC - Ceftazidime-avibactam, Polymixin  Metallo beta-lactamase (MBL) i.e VIM, IMP, NDM - Ceftazidime-avibactam plus aztreonam, polymyxin, Cefiderocol  The impact of appropriate antibiotic administration on 30-day mortality was seen. Results: A total of 79 blood samples were submitted for film array assay during the study period. The mean age of the study population was 17± 4 years. 41(51.9%) patients had acute myeloid leukemia (AML), 29 (36.7%) had acute lymphocytic leukemia (ALL), 4 (5%) patients had lymphoma and 5 (6.3%) had other malignancies. 54(68.3%) BSI had microorganism with antibiotic resistance gene, 16 (20.3%) did not carry resistance gene and in 9 (11.4%), microorganism was not identified in film array assay, though conventional culture showed contaminants. Of the 54 BSI with microorganisms having antibiotic resistance gene, 37(68.5%) had MBL gene either alone or along with CTX-M or OXA-48 like genes, 12 (22.2%) had CTX-M and 5 (9.2%) had both CTX-M and OXA -48 like genes. Empirical antibiotic did not match the antibiotic resistance pattern in 40 (74.1%), antibiotic matched the resistance pattern in 14(22.9%). Antibiotic adjustment was done in 32 (86%) of MBL, 4 (80%) of OXA-48 like with CTX-M and 9 (75%) CTX-M. The 30-day mortality was significantly less (28% vs 80%, p = 0.042) in patients who received appropriate antibiotic versus those who continued inappropriate antibiotics in MBL BSI. Conclusions: Majority of the study population had BSI with antibiotic resistance gene and underwent a change in the antibiotic after the assay. There was lesser 30-day mortality in patients who received antibiotics appropriate for the identified resistance gene. Molecular technique is helpful for precise antibiotic administration in cancer patients who have a higher risk of infection with organisms having resistance gene.