Clinical Outcomes of Carbapenem-Resistant <i>Acinetobacter baumannii</i> Bloodstream Infections: Study of a 2-State Monoclonal Outbreak

Munoz-Price, L. Silvia; Zembower, Teresa; Penugonda, Sudhir; Schreckenberger, Paul C.; Lavin, Mary Alice; Welbel, Sharon F.; Vais, Dana; Baig, M.W.; Mohapatra, Sunita; Quinn, John P.; Weinstein, Robert A.

doi:10.1086/656247

Cited by 63 publications

(53 citation statements)

References 14 publications

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“…Of these, A. baumannii is the most common cause of infection. This bacterium is frequently isolated from critically ill hospitalized patients and often causes outbreaks (2)(3)(4). Infections with A. baumannii have been associated with high attributable mortality and increased length of hospital stay, with multidrug resistance often being a predictor of poor clinical outcomes (5,6).…”

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confidence: 99%

Utility of Whole-Genome Sequencing in Characterizing Acinetobacter Epidemiology and Analyzing Hospital Outbreaks

2016

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bAcinetobacter baumannii frequently causes nosocomial infections and outbreaks. Whole-genome sequencing (WGS) is a promising technique for strain typing and outbreak investigations. We compared the performance of conventional methods with WGS for strain typing clinical Acinetobacter isolates and analyzing a carbapenem-resistant A. baumannii (CRAB) outbreak. We performed two band-based typing techniques (pulsed-field gel electrophoresis and repetitive extragenic palindromic-PCR), multilocus sequence type (MLST) analysis, and WGS on 148 Acinetobacter calcoaceticus-A. baumannii complex bloodstream isolates collected from a single hospital from 2005 to 2012. Phylogenetic trees inferred from core-genome single nucleotide polymorphisms (SNPs) confirmed three Acinetobacter species within this collection. Four major A. baumannii clonal lineages (as defined by MLST) circulated during the study, three of which are globally distributed and one of which is novel. WGS indicated that a threshold of 2,500 core SNPs accurately distinguished A. baumannii isolates from different clonal lineages. The bandbased techniques performed poorly in assigning isolates to clonal lineages and exhibited little agreement with sequence-based techniques. After applying WGS to a CRAB outbreak that occurred during the study, we identified a threshold of 2.5 core SNPs that distinguished nonoutbreak from outbreak strains. WGS was more discriminatory than the band-based techniques and was used to construct a more accurate transmission map that resolved many of the plausible transmission routes suggested by epidemiologic links. Our study demonstrates that WGS is superior to conventional techniques for A. baumannii strain typing and outbreak analysis. These findings support the incorporation of WGS into health care infection prevention efforts.A n important role of clinical microbiology is to identify relationships between bacterial isolates. At a broad level, phenotypic and genotypic tests are used to categorize bacterial isolates into the same or different species. Within a bacterial species, techniques are used to group isolates into clonal lineages, which are groups of closely related bacteria that share a recent common ancestor but have spread regionally or globally. At a more local level, infection control practitioners must determine whether a group of isolates constitutes a hospital outbreak by ascertaining whether the isolates have a degree of similarity consistent with a common source within the hospital. Once isolates belonging to a hospital outbreak have been identified, similarities and differences between these isolates can be exploited to generate a transmission map to aid in finding the source of the outbreak and in disrupting ongoing pathways of transmission. For some groups of bacteria, such as Acinetobacter, discernment at each level has medically important consequences and therefore must be accomplished by hospital-associated clinical microbiology laboratories.Within the Acinetobacter genus, the Acinetobacter calcoaceticusAcinetobac...

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confidence: 99%

Utility of Whole-Genome Sequencing in Characterizing Acinetobacter Epidemiology and Analyzing Hospital Outbreaks

2016

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“…The 30-day mortality rates associated with bloodstream infections were reported as 44.8 % for patients with carbapenem-susceptible P. aeruginosa bacteremia, 54.2 % for patients with carbapenem-resistant P. aeruginosa bacteremia, and 41 % for patients with carbapenem-resistant A. baumannii. [14,15]. The severity of organ failure and leukocytosis at bacteremia onset, age, bacteremia, inadequate empiric treatment, and inadequate definitive treatment were reported to be independently associated with mortality in patients with carbapenem-resistant A. baumannii-related bacteremia [16,17].…”

Section: Discussionmentioning

confidence: 99%

Which Multidrug-Resitant Bacteria are Emerging in Patients with Hematological Malignancies?: One-Year Report

Gedık

Şimşek²,

Yıldırmak³

et al. 2014

Indian J Hematol Blood Transfus

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The aim of this retrospective, observational study was to evaluate the outcomes of bacteremia attacks during neutropenic episodes caused by chemotherapy in patients with hematological cancers by assessing mortality, involved pathogens, antimicrobial therapy and treatment responses. Patients who were older than 14 years of age and developed at least one neutropenic episode after chemotherapy to treat hematological cancer between November 2011 and November 2012 were included in the study. We retrospectively collected demographic, treatment, and survival data for 68 patients with 129 neutropenic episodes. The mean age was 59.36 ± 15.22 years (range 17-80 years), and 41 cases were male. The mean Multinational Association of Supportive Care in Cancer score was 19.56 ± 9.04. A total of 37 (28 %) bacteremia attacks were recorded in 20 cases (29 %). Fatality rates were 50 % in the six cases with bacteremia caused by carbapenem-resistant Gram-negative bacteria; death occurred in two patients with carbapenem-resistant Acinetobacter baumannii and in one patient with carbapenem-resistant Pseudomonas aeruginosa. Clinical and microbiological responses were achieved using PIP-TAZ or CEP-SUL treatment in 80 % (16/20) of the cases with bacteremia caused by carbapenem-sensitive Gram-negative bacteria (CS-GNB). During 547 colonization-days in 21 (30 %) vancomycinresistant enterococci (VRE)-colonized cases among 68 patients, vancomycin-resistant Enterococcus faecium bacteremia developed in two patients. Non-carbapenem-based therapy can cure most bacteremia attacks caused by CS-GNB in patients with hematological cancer. However, bacteremia and other infections caused by drug-resistant pathogens, such as A. baumannii, P. aeruginosa, and VRE, are a growing concern in hematological patients.

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“…9 As a result, physicians believe that those episodes represent "specimen contamination" or "transient bacteremia" among patients at risk of skin colonization. 10 The notion that A. baumannii is "less virulent" than other Gram-negative bacilli has also been advanced. This opinion lies in stark contrast to the reports of A. baumannii causing devastating necrotizing skin and soft tissue infections.…”

Section: The Evolving Clinical Landscape Of Infections Caused By a Bmentioning

confidence: 99%

Are we closing in on an "elusive enemy"? The current status of our battle withAcinetobacter baumannii

Perez¹,

Ponce-Terashima²,

Adams³

2011

Virulence

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Clinical Outcomes of Carbapenem-Resistant Acinetobacter baumannii Bloodstream Infections: Study of a 2-State Monoclonal Outbreak

Abstract: To our knowledge, this is the first time a study has described 2 patterns of bloodstream infection with A. baumannii: single versus multiple positive blood culture results, as well as a subset of patients with prolonged bacteremia.

Cited by 63 publications

References 14 publications

Utility of Whole-Genome Sequencing in Characterizing Acinetobacter Epidemiology and Analyzing Hospital Outbreaks

Utility of Whole-Genome Sequencing in Characterizing Acinetobacter Epidemiology and Analyzing Hospital Outbreaks

Which Multidrug-Resitant Bacteria are Emerging in Patients with Hematological Malignancies?: One-Year Report

Are we closing in on an "elusive enemy"? The current status of our battle withAcinetobacter baumannii

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