The significance of Acinetobacter baumannii bacteraemia compared with Klebsiella pneumoniae bacteraemia: risk factors and outcomes

Robenshtok, Eyal; Paul, Mical; Leibovici, Leonard; Fraser, Abigail; Pitlik, Silvio; Ostfeld, Ishay; Samra, Zmira; Pérez, S. Cano; Lev, Bruria; Weinberger, Miriam

doi:10.1016/j.jhin.2006.06.025

Cited by 79 publications

(60 citation statements)

References 19 publications

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“…Interestingly, when outcomes from A. baumannii bacteremia were compared directly to those for patients who had bacteremia with other gram-negative organisms, including Klebsiella pneumoniae, a significant increase in mortality was noted for A. baumannii (266,462). A further study showed a significant increase in mortality with multidrug-resistant A. baumannii colonization or infection compared to that with multidrugresistant Pseudomonas aeruginosa colonization or infection, using a Kaplan-Meier analysis (198).…”

Section: Clinical Impact Of Acinetobacter Baumannii Infectionmentioning

confidence: 99%

Acinetobacter baumannii : Emergence of a Successful Pathogen

2008

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SUMMARY Acinetobacter baumannii has emerged as a highly troublesome pathogen for many institutions globally. As a consequence of its immense ability to acquire or upregulate antibiotic drug resistance determinants, it has justifiably been propelled to the forefront of scientific attention. Apart from its predilection for the seriously ill within intensive care units, A. baumannii has more recently caused a range of infectious syndromes in military personnel injured in the Iraq and Afghanistan conflicts. This review details the significant advances that have been made in our understanding of this remarkable organism over the last 10 years, including current taxonomy and species identification, issues with susceptibility testing, mechanisms of antibiotic resistance, global epidemiology, clinical impact of infection, host-pathogen interactions, and infection control and therapeutic considerations.

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Section: Clinical Impact Of Acinetobacter Baumannii Infectionmentioning

confidence: 99%

Acinetobacter baumannii : Emergence of a Successful Pathogen

2008

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“…are now the third leading cause of respiratory tract infections among patients in intensive care units, and A. baumannii is responsible for up to 10% of hospital-acquired infections (26). These nosocomial infections are typically found in immunocompromised patients and are associated with an increased length of stay and excess morbidity (13,25,38,47). In intensive care units, up to 30% of A. baumannii clinical isolates are resistant to at least three classes of antibiotics (26).…”

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confidence: 99%

Comparative Genome Sequence Analysis of Multidrug-Resistant Acinetobacter baumannii

Adams¹,

Goglin²,

Molyneaux³

et al. 2008

J Bacteriol

421

420

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The recent emergence of multidrug resistance (MDR) in Acinetobacter baumannii has raised concern in health care settings worldwide. In order to understand the repertoire of resistance determinants and their organization and origins, we compared the genome sequences of three MDR and three drug-susceptible A. baumannii isolates. The entire MDR phenotype can be explained by the acquisition of discrete resistance determinants distributed throughout the genome. A comparison of closely related MDR and drug-susceptible isolates suggests that drug efflux may be a less significant contributor to resistance to certain classes of antibiotics than inactivation enzymes are. A resistance island with a variable composition of resistance determinants interspersed with transposons, integrons, and other mobile genetic elements is a significant but not universal contributor to the MDR phenotype. Four hundred seventy-five genes are shared among all six clinical isolates but absent from the related environmental species Acinetobacter baylyi ADP1. These genes are enriched for transcription factors and transporters and suggest physiological features of A. baumannii that are related to adaptation for growth in association with humans.Among gram-negative pathogens that are reported as "multidrug resistant" (MDR), Acinetobacter baumannii is rapidly becoming a focus of significant attention (1,10,35,56). A. baumannii, a pleomorphic, gram-negative coccobacillus, is currently recognized by the Infectious Diseases Society of America as one of the most important pathogens threatening our health care delivery system (48). Global surveillance programs conducted over the last decade show an unparalleled increase in resistance rates among clinical Acinetobacter isolates (26). Acinetobacter spp. are now the third leading cause of respiratory tract infections among patients in intensive care units, and A. baumannii is responsible for up to 10% of hospital-acquired infections (26). These nosocomial infections are typically found in immunocompromised patients and are associated with an increased length of stay and excess morbidity (13,25,38,47 (19,40). Molecular typing of isolates from this outbreak revealed eight major clone types, and about 60% of the isolates were related to three pan-European types (5, 52), suggesting multiple independent origins (40). Examination of specific resistance determinants in the WRAMC isolates demonstrated considerable variability in the composition of resistance genes within each clone type and similar patterns across certain divergent clone types. Thus, genetic relatedness was a poor predictor of the MDR phenotype. This led to the hypothesis that there exist multiple independent genetic mechanisms leading to MDR in A. baumannii. A large cluster of antibiotic resistance genes and mobile genetic elements is present as an 86-kb "resistance island" (RI) in the A. baumannii AYE genome (15). The RI is not present in the genomes of the drug-susceptible A. baumannii isolates ATCC 17978 (43) and SDF (51), suggesting that it i...

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“…Mortality rates associated with A. baumannii infection range from 19 to 54% (20). Mortality associated with Gram-negative bacteremia was significantly increased in patients with A. baumannii compared to other Gram-negative bacilli (GNB) (23,35). The changing epidemiology, the increasing incidence of infection, and the significant mortality with A. baumannii establishes it as a pathogen of increasing medical importance.…”

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confidence: 99%

The K1 Capsular Polysaccharide of Acinetobacter baumannii Strain 307-0294 Is a Major Virulence Factor

et al. 2010

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Acinetobacter baumannii is a pathogen of increasing medical importance with a propensity to be multidrug resistant, thereby making treatment challenging. Little is known of virulence traits in A. baumannii. To identify virulence factors and potential drug targets, random transposon (Tn) mutants derived from the A. baumannii strain AB307-0294 were screened to identify genes essential for growth in human ascites fluid in vitro, an inflammatory exudative fluid. These studies led to the identification of two genes that were predicted to be required for capsule polymerization and assembly. The first, ptk, encodes a putative protein tyrosine kinase (PTK), and the second, epsA, encodes a putative polysaccharide export outer membrane protein (EpsA). Monoclonal antibodies used in flow cytometric and Western analyses confirmed that these genes are required for a capsule-positive phenotype. A capsule-positive phenotype significantly optimized growth in human ascites fluid, survival in human serum, and survival in a rat soft tissue infection model. Importantly, the clearance of the capsule-minus mutants AB307.30 (ptk mutant, capsule minus) and AB307.45 (epsA mutant, capsule minus) was complete and durable. These data demonstrated that the K1 capsule from AB307-0294 was an important protectin. Further, these data suggested that conserved proteins, which contribute to the capsule-positive phenotype, are potential antivirulence drug targets. Therefore, the results from this study have important biologic and translational implications and, to the best of our knowledge, are the first to address the role of capsule in the pathogenesis of A. baumannii infection.

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The significance of Acinetobacter baumannii bacteraemia compared with Klebsiella pneumoniae bacteraemia: risk factors and outcomes

Cited by 79 publications

References 19 publications

Acinetobacter baumannii : Emergence of a Successful Pathogen

Acinetobacter baumannii : Emergence of a Successful Pathogen

Comparative Genome Sequence Analysis of Multidrug-Resistant Acinetobacter baumannii

The K1 Capsular Polysaccharide of Acinetobacter baumannii Strain 307-0294 Is a Major Virulence Factor

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