Pathogenic Significance of <i>Acinetobacter calcoaceticus</i>: Analysis of Experimental Infection in Mice

Obana, Yoshiki

doi:10.1111/j.1348-0421.1986.tb02991.x

Cited by 34 publications

(23 citation statements)

References 20 publications

(24 reference statements)

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“…In contrast, only a few reports describing different aspects related to the basic physiology, genetics, and molecular biology of this opportunistic pathogen (2,12,13,19,20,41,58) could be found during these literature searches. The apparent lack of suitable genetic methods such as random mutagenesis with transposable elements, which is a widely used approach to characterize bacteria genetically and functionally, appears to be the reason for the delay of the characterization of this human pathogen.…”

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confidence: 89%

Genetic and Phenotypic Analysis of Acinetobacter baumannii Insertion Derivatives Generated with a Transposome System

Dorsey

Tomaras

Actis

2002

Appl Environ Microbiol

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Acinetobacter baumannii is a metabolically versatile pathogen that causes severe infections in compromised patients. However, little is known about the genes and factors involved in its basic physiology and virulence properties. Insertion mutagenesis was used to initiate the identification and characterization of some of these factors and genes in the prototype strain 19606. The utilization of the pLOFKm suicide delivery vector, which harbors a suicide mini-Tn10 derivative, proved to be unsuccessful for this purpose. The EZ::TN ͗R6K␥ori/ KAN-2͘ Tnp transposome system available from Epicentre was then used in conjunction with electroporation to generate isogenic insertional derivatives of A. baumannii 19606. Replica plating showed that 2% of the colonies that grew after electroporation on agar plates without antibiotics also grew in the presence of 40 g of kanamycin per ml. DNA hybridization proved that all of the kanamycin-resistant derivatives contained the EZ::TN ͗R6K␥ori/KAN-2͘ insertion element, which was mapped to different genomic locations. Replica plating on Simmons citrate agar and microtiter plate-plastic tube assays identified growth-and biofilm-defective derivatives, respectively. The location of the insertion in several of these derivatives was determined by self-ligation of NdeI-or EcoRI-digested genomic DNA and electroporation of Escherichia coli TransforMax EC100D (pir ؉ ). Sequence analysis of the recovered plasmids showed that some of the A. baumannii 19606 growth-defective derivatives contain insertions within genes encoding activities required for the generation of energy and cell wall components and for the biosynthesis of amino acids and purines. A gene encoding a protein similar to the GacS sensor kinase was interrupted in four derivatives, while another had an insertion in a gene coding for a hypothetical sensor kinase. A. baumannii 19606 derivatives with defective attachment or biofilm phenotypes had insertions within genes that appear to be part of a chaperone-usher transport system described for other bacteria. DNA hybridization experiments showed that the presence of strain 19606 genes encoding regulatory and attachment or biofilm functions is widespread among other A. baumannii clinical isolates.Acinetobacter baumannii is being increasingly recognized as an important pathogen that causes severe infections in hospitalized patients (6, 7). In addition, deadly cases of communityacquired pneumonia were reported among compromised patients (3, 9). These infections are difficult to treat due to the expanding antibiotic resistance of the clinical strains (8, 30), which represents one of the most difficult problems confronted by clinicians who deal with the infections caused by this human pathogen.Literature searches showed that there are numerous reports describing either the different types of infections caused by A. baumannii, the antibiotic resistance profiles of the different clinical strains, the characterization of some of the genetic elements responsible for their antibiotic resistanc...

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confidence: 89%

Genetic and Phenotypic Analysis of Acinetobacter baumannii Insertion Derivatives Generated with a Transposome System

Dorsey

Tomaras

Actis

2002

Appl Environ Microbiol

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“…Analysis of experimental infections in mice (49) showed that the slime ofA. baumannii is a virulence factor that acts by impairing the functions and cell structure of mice phagocytes.…”

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confidence: 99%

“…Nevertheless, most infections have occurred in patients compromised by either antibiotic therapy, respiratory instrumentation and manipulations, dialysis, or surgery (18,19,39,70). Thus, it was proposed that reduced host defenses and interaction with other bacterial species, rather than the expression of specific bacterial virulence factors (49), are the factors responsible for opportunistic infections caused by Acinetobacter species.…”

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Characterization of a high-affinity iron transport system in Acinetobacter baumannii

et al. 1992

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Analysis of a clinical isolate ofAcinetobacter baumannii showed that this bacterium was able to grow under iron-limiting conditions, using chemically defined growth media containing different iron chelators such as human transferrin, ethylenediaminedi-(o-hydroxyphenyl)acetic acid, nitrilotriacetic acid, and 2,2'-bipyridyl. This iron uptake-proficient phenotype was due to the synthesis and secretion of a catechol-type siderophore compound. Utilization bioassays using the SalmoneUla typhimurium iron uptake mutants enb-1 and enb-7 proved that this siderophore is different from enterobactin. This catechol siderophore was partially purified from culture supernatants by adsorption chromatography using an XAD-7 resin. The purified component exhibited a chromatographic behavior and a UV-visible light absorption spectrum different from those of 2,3-dihydroxybenzoic acid and other bacterial catechol siderophores. Furthermore, the siderophore activity of this extraceliular catechol was confirmed by its ability to stimulate energy-dependent uptake of 55Fe(M) as well as to promote the growth of A. baumannii bacterial cells under iron-deficient conditions imposed by 60 ,uM human transferrin. Polyacrylamide gel electrophoresis analysis showed the presence of iron-regulated proteins in both inner and outer membranes of this clinical isolate ofA. baumannii. Some of these membrane proteins may be involved in the recognition and internalization of the iron-siderophore complexes.Acinetobacter baumannii, formerly known asAcinetobacter calcoaceticus subsp. anitratus (15), belongs to a bacterial species that is widely distributed throughout the environment (6). This microorganism can be isolated from the skin (3, 43) and respiratory tract (59) of healthy ambulatory adults as well as from hospital personnel and equipment (36,39,46,67).Lately, numerous outbreaks of nosocomial infections caused by A. baumannii have been reported (7-10, 16, 42, 47, 56, 57, 73), which are of particular concern because of the widespread and increasing antibiotic resistance of the isolated strains (17,30,32,33,40,41,48). Nevertheless, most infections have occurred in patients compromised by either antibiotic therapy, respiratory instrumentation and manipulations, dialysis, or surgery (18,19,39,70). Thus, it was proposed that reduced host defenses and interaction with other bacterial species, rather than the expression of specific bacterial virulence factors (49), are the factors responsible for opportunistic infections caused by Acinetobacter species.Acinetobacter species are able to survive under restricted nutrient conditions, such as those imposed by the host. Iron is one of the essential bacterial nutrients that is tightly controlled by the host, through its chelation by the highaffinity binding glycoproteins transferrin (TF) and lactoferrin (23). Thus, bacteria have developed efficient iron uptake mechanisms that allow them to scavenge iron from these host proteins, either by direct interaction with the ironprotein complexes (34) or by the synthesis an...

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“…), and there is experimental evidence suggesting that exopolysaccharide-producing strains of Acinetobacter spp. enhance the virulence of other gram-negative species in polymicrobial infections [52,53]. One could also speculate that chemical signals elaborated by the co-pathogen may activate biofilm formation by enhancing auto-inducer synthase production in A. baumannii, or vice versa [54].…”

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confidence: 99%

Acinetobacter baumannii-Associated Skin and Soft Tissue Infections: Recognizing a Broadening Spectrum of Disease

Guerrero

Pérez

Conger

et al. 2010

Surgical Infections

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Background: Acinetobacter baumannii is gaining importance as a cause of nosocomial infections, but its role in skin and soft tissue infection (SSTI) is not well defined. As a result of the outbreak of A. baumannii occurring in military personnel in Iraq and Afghanistan, reports of severe wound infections and SSTI caused by this pathogen are increasing in frequency. Methods: We describe four cases of monomicrobial and polymicrobial A. baumannii-associated necrotizing SSTI accompanied by A. baumannii bacteremia and offer a review of similar experiences published in the literature. Results: Our comparative analysis reveals four unique features associated with necrotizing SSTI associated with A. baumannii: i) Occurs in hosts with underlying comorbidities (e.g., trauma, cirrhosis); ii) is often accompanied by bacteremia; iii) multiple drug resistance and the presence of co-pathogens frequently complicated treatment (64% of cases); iv) the cases reported here and in our review required surgical debridement (84% of cases) and led to substantial mortality (*30%). Conclusions: As the prevalence of A. baumannii continues to increase in our health care system, SSTIs caused by this organism may become more common. Clinicians must be aware that the spectrum of disease caused by A. baumannii could include severe necrotizing SSTI and that vigilance for potential complications is necessary.

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Pathogenic Significance of Acinetobacter calcoaceticus: Analysis of Experimental Infection in Mice

Abstract: The phenomenon that mixed infection with certain species of bacteria and Acinetobacter calcoaceticus is more virulent than single infection was analyzed experimentally.

Cited by 34 publications

References 20 publications

Genetic and Phenotypic Analysis of Acinetobacter baumannii Insertion Derivatives Generated with a Transposome System

Genetic and Phenotypic Analysis of Acinetobacter baumannii Insertion Derivatives Generated with a Transposome System

Characterization of a high-affinity iron transport system in Acinetobacter baumannii

Acinetobacter baumannii-Associated Skin and Soft Tissue Infections: Recognizing a Broadening Spectrum of Disease

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