<i>Acinetobacter baumannii</i>Skin and Soft‐Tissue Infection Associated with War Trauma

Sebeny, Peter J.; Riddle, Mark S.; Petersen, Kyle

doi:10.1086/590568

Cited by 169 publications

(114 citation statements)

References 18 publications

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“…These Gram-negative bacteria are responsible for increasing numbers of infections encountered in hospitals, particularly among immunocompromised patients (1,2), and community-acquired infections are also increasing in prevalence (3). A recently recognized population at particular risk for Acinetobacter infections is military service members who have suffered combat-related injuries, who often acquire these infections in field hospitals (4)(5)(6). Although Acinetobacter spp.…”

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confidence: 99%

Pathogenic Acinetobacter: from the Cell Surface to Infinity and Beyond

2016

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The genus Acinetobacter encompasses multiple nosocomial opportunistic pathogens that are of increasing worldwide relevance because of their ability to survive exposure to various antimicrobial and sterilization agents. Among these, Acinetobacter baumannii, Acinetobacter nosocomialis, and Acinetobacter pittii are the most frequently isolated in hospitals around the world. Despite the growing incidence of multidrug-resistant Acinetobacter spp., little is known about the factors that contribute to pathogenesis. New strategies for treating and managing infections caused by multidrug-resistant Acinetobacter strains are urgently needed, and this requires a detailed understanding of the pathobiology of these organisms. In recent years, some virulence factors important for Acinetobacter colonization have started to emerge. In this review, we focus on several recently described virulence factors that act at the bacterial surface level, such as the capsule, O-linked protein glycosylation, and adhesins. Furthermore, we describe the current knowledge regarding the type II and type VI secretion systems present in these strains.

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confidence: 99%

Pathogenic Acinetobacter: from the Cell Surface to Infinity and Beyond

2016

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“…These bacteria are primarily associated with infections in hospital settings or in patients that are immunocompromised or severely injured (2)(3)(4)(5)(6)(7)(8)(9). The ability to treat infections due to members of the Acinetobacter baumannii-calcoaceticus complex has been complicated by extensive resistance to multiple classes of antibiotics (10)(11)(12)(13)(14)(15).…”

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confidence: 99%

Phase-Variable Control of Multiple Phenotypes in Acinetobacter baumannii Strain AB5075

2015

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Acinetobacter baumannii strain AB5075 produces colonies with two opacity phenotypes, designated opaque and translucent. These phenotypes were unstable and opaque and translucent colony variants were observed to interconvert at high frequency, suggesting that a phase-variable mechanism was responsible. The frequency of phase variation both within colonies and in broth cultures increased in a cell density-dependent manner and was mediated by the accumulation of an extracellular factor. This factor was distinct from the known A. baumannii signaling molecule 3-OH C 12 -homoserine lactone. Opaque and translucent colony variants exhibited a number of phenotypic differences, including cell morphology, surface motility, biofilm formation, antibiotic resistance, and virulence in a Galleria mellonella model. Additional clinical isolates exhibited a similar phase-variable control of colony opacity, suggesting that this may be a common feature of A. baumannii. IMPORTANCEA novel phase-variable mechanism has been identified in Acinetobacter baumannii that results in an interconversion between opaque and translucent colony phenotypes. This phase variation also coordinately regulates motility, cell shape, biofilm formation, antibiotic resistance, and virulence. The frequency of phase variation is increased at high cell density via a diffusible extracellular signal. To our knowledge, this report presents the first example of phase variation in A. baumannii and also the first example of quorum sensing-mediated control of phase variation in a bacterium. The findings are important, as this phase-variable mechanism can be identified only via changes in colony opacity using oblique light; therefore, many researchers studying A. baumannii may unknowingly be working with different colony variants.

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“…The most common type of infection caused by A. baumannii is ventilatorassociated pneumonia; however, A. baumannii can cause a range of infections, including wound and burn infections, sepsis, urinary tract infections, meningitis, and osteomyelitis (1,3,4). Additionally, A. baumannii infections have been frequently identified in American military personnel returning from the Middle East, and community-acquired infections have been reported in southeast Asia and Australia (5)(6)(7)(8). Exacerbating morbidity and mortality caused by A. baumannii is the high rate of acquired antibiotic resistance, and multidrug-and pan-drug-resistant strains of A. baumannii are increasingly being identified (9)(10)(11).…”

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confidence: 99%

Acinetobacter baumannii Response to Host-Mediated Zinc Limitation Requires the Transcriptional Regulator Zur

et al. 2014

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Acinetobacter baumannii is a leading cause of ventilator-associated pneumonia in intensive care units, and the increasing rates of antibiotic resistance make treating these infections challenging. Consequently, there is an urgent need to develop new antimicrobials to treat A. baumannii infections. One potential therapeutic option is to target bacterial systems involved in maintaining appropriate metal homeostasis, processes that are critical for the growth of pathogens within the host. The A. baumannii inner membrane zinc transporter ZnuABC is required for growth under low-zinc conditions and for A. baumannii pathogenesis. The expression of znuABC is regulated by the transcriptional repressor Zur. To investigate the role of Zur during the A. baumannii response to zinc limitation, a zur deletion mutant was generated, and transcriptional changes were analyzed using RNA sequencing. A number of Zur-regulated genes were identified that exhibit increased expression both when zur is absent and under lowzinc conditions, and Zur binds to predicted Zur box sequences of several genes affected by zinc levels or the zur mutation. Furthermore, the zur mutant is impaired for growth in the presence of both high and low zinc levels compared to wild-type A. baumannii. Finally, the zur mutant exhibits a defect in dissemination in a mouse model of A. baumannii pneumonia, establishing zinc sensing as a critical process during A. baumannii infection. These results define Zur-regulated genes within A. baumannii and demonstrate a requirement for Zur in the A. baumannii response to the various zinc levels experienced within the vertebrate host.

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Acinetobacter baumanniiSkin and Soft‐Tissue Infection Associated with War Trauma

Cited by 169 publications

References 18 publications

Pathogenic Acinetobacter: from the Cell Surface to Infinity and Beyond

Pathogenic Acinetobacter: from the Cell Surface to Infinity and Beyond

Phase-Variable Control of Multiple Phenotypes in Acinetobacter baumannii Strain AB5075

Acinetobacter baumannii Response to Host-Mediated Zinc Limitation Requires the Transcriptional Regulator Zur

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