Acinetobacter baumannii is a highly antibiotic-resistant bacterial pathogen for which novel therapeutic approaches are needed. Unfortunately, the drivers of virulence in A . remain uncertain. By comparing genomes among panel strains we identified specific gene variation capsule locus that correlated with altered virulence. While less virulent possessed intact gtr6 , hypervirulent clinical isolate contained spontaneous transposon insertion same gene, resulting loss branchpoint capsular...

Acinetobacter baumannii (Ab) is a nosocomial pathogen with one of the highest rates multidrug resistance (MDR). This partially due to transmissible plasmids. Many Ab strains harbor constitutively active type VI secretion system (T6SS) that employed kill nonkin bacteria. T6SS and plasmid conjugation both involve cell-to-cell contact. Paradoxically, successful requires survival recipient, which target T6SS. Thus, an in either donor or recipient poses challenge conjugation. Here, we show large...

Pathogenic Acinetobacter species, including baumannii and nosocomialis, are opportunistic human pathogens of increasing relevance worldwide. Although their mechanisms drug resistance well studied, the virulence factors that govern pathogenesis incompletely characterized. Here we define complete secretome A. nosocomialis strain M2 in minimal medium demonstrate pathogenic species produce both a functional type I secretion system (T1SS) contact-dependent inhibition (CDI) system. Using...

Peptidoglycan (PG) is essential in most bacteria. Thus, it often targeted by various assaults, including interbacterial attacks via the type VI secretion system (T6SS). Here, we report that Gram-negative bacterium Acinetobacter baumannii strain ATCC 17978 produces, secretes, and incorporates noncanonical d-amino acid d-lysine into its PG during stationary phase. We show editing increases competitiveness of A. bacterial warfare providing immunity against peptidoglycan-targeting T6SS effectors...

Acinetobacter baumannii causes a wide range of infections that are difficult to treat due increasing rates multidrug resistance; however, the mechanisms this pathogen uses respond stress poorly understood. Here, we describe new mechanism signaling in is mediated by metabolite phenylacetic acid (PAA).

The antibiotic-resistant bacterium Acinetobacter baumannii is a leading cause of hospital-associated infections. Despite surveillance and infection control efforts, new A. strains are regularly isolated from health care facilities worldwide. In mouse model urinary tract infection, we found that mice infected with displayed high bacterial burdens in urine for several weeks. Two months after the resolution inserting catheter into bladder resolved led to resurgence same-strain ~53% within 24...

Serratia marcescens is a Gram-negative bacterium that thrives in wide variety of ambient niches and interacts with an ample range hosts. As opportunistic human pathogen, it has increased its clinical incidence recent years, being responsible for life-threatening nosocomial infections. S. produces numerous exoproteins toxic effects, including the ShlA pore-forming toxin, which been catalogued as most potent cytotoxin. However, regulatory mechanisms govern expression, well action toward host,...

CpaA is a glycoprotease expressed by members of the Acinetobacter baumannii-calcoaceticus complex, and it first bona fide secreted virulence factor identified in these species. Here, we show that cleaves multiple targets precisely at O -glycosylation sites preceded Pro residue. This feature, together with observation sialic acid does not impact activity, makes this enzyme an attractive tool for analysis -linked human protein biotechnical diagnostic purposes. Previous work proteins involved...

Multidrug-resistant Acinetobacter baumannii infections are increasing at alarming rates. Therefore, novel antibiotic-sparing treatments to combat these A . urgently needed. The development of interventions would benefit from a better understanding this bacterium’s pathobiology, which remains poorly understood. is regarded as an extracellular opportunistic pathogen. However, research on has largely focused common lab strains, such ATCC 19606, that have been isolated several decades ago. These...

Serratia marcescens is an opportunistic human pathogen that represents a growing problem for public health, particularly in hospitalized or immunocompromised patients. However, little known about factors and mechanisms contribute to S. pathogenesis within its host. In this work, we explore the invasion process of epithelial cells. We demonstrate once internalized, able not only persist but also multiply inside large membrane-bound compartment. This structure displays autophagic-like...

While pathogenic Acinetobacter can cause various infections, we recently found that 20% of clinical isolates come from urinary sources. Despite the relevance as a uropathogen, few virulence factors involved in tract colonization have been defined.

Nosocomial pathogens of the Acinetobacter calcoaceticus-baumannii (ACB) complex are a cautionary example for world-wide spread multi- and pan-drug resistant bacteria. Aiding urgent demand novel therapeutic targets, comparative genomics studies between their apathogenic relatives shed light on genetic basis human-pathogen interaction. Yet, existing limited in taxonomic scope, sensing phylogenetic signal, resolution by largely analyzing genes independent organization functional gene clusters....

Multidrug-resistant Acinetobacter baumannii infections are an urgent clinical problem and can cause difficult-to-treat nosocomial infections. During such infections, like catheter-associated urinary tract (CAUTI), A. rely on adhesive, extracellular fibers, called chaperone-usher pathway (CUP) pili for critical binding interactions. The uropathogenic strain, UPAB1, the pan-European subclone II isolate, ACICU, use CUP Abp1 Abp2 (previously termed Cup Prp, respectively) in tandem to establish...

Bacterial pneumonia is a common infection of the lower respiratory tract that can afflict patients all ages. Multidrug-resistant strains Acinetobacter baumannii are increasingly responsible for causing nosocomial pneumonias, thus posing an urgent threat. Alveolar macrophages play critical role in overcoming infections caused by this pathogen. Recently, we and others have shown new clinical isolates A. baumannii, but not lab strain ATCC 19606 (19606), persist replicate within spacious...

Abstract Although considered primarily extracellular, Acinetobacter baumannii can survive and replicate within macrophages in vitro . Intracellular bacteria are often protected from the host immune system antibiotic treatment, potentially leading to chronic or recurrent infections. To investigate role of intracellular A. during infection, we transferred infected bronchoalveolar lavage fluid (BALF), containing an bacterial population, naïve immunocompromised mice. This BALF transfer resulted...

ABSTRACT Successful pathogens must be able to adapt a multitude of stressors imposed by their host. Acinetobacter baumannii has emerged as major global health threat due its exceptional ability hostile environments and skyrocketing rates multidrug resistance. Recent studies have begun explore the importance tRNA methylation in regulation bacterial stress responses, including adaptation antibiotic oxidative stresses. However, methyltransferases (trms) not been investigated A. . Bioinformatic...

ABSTRACT Serratia marcescens is able to invade, persist, and multiply inside nonphagocytic cells, residing in nonacidic, nondegradative, autophagosome-like vacuoles. In this work, we have examined the physiological role of PhoP/PhoQ system its function control critical virulence phenotypes S. . We demonstrated involvement adaptation bacterium growth on scarce environmental Mg 2+ , at acidic pH, presence polymyxin B. also shown that these conditions constitute signals activate system. found...

Several pathogens co-opt host intracellular compartments to survive and replicate, they thereafter disperse progeny prosper in a new niche. Little is known about strategies displayed by Serratia marcescens defeat immune responses disseminate afterwards. Upon invasion of nonphagocytic cells, multiplies within autophagosome-like vacuoles. These Serratia-containing vacuoles (SeCV) circumvent progression into acidic/degradative compartments, avoiding elimination. In this work, we show that ShlA...

Acinetobacter baumannii is emerging as a multidrug-resistant (MDR) nosocomial pathogen of increasing threat to human health worldwide. The recent MDR urinary isolate UPAB1 carries the plasmid pAB5, member family large conjugative plasmids (LCPs). LCPs encode several antibiotic resistance genes and repress type VI secretion system (T6SS) enable their dissemination, employing two TetR transcriptional regulators. Furthermore, pAB5 controls expression additional chromosomally encoded genes,...

Abstract Serratia marcescens is an opportunistic bacterium that infects a wide range of hosts including humans. It potent pathogen in septic injury model Drosophila melanogaster since few bacteria directly injected the body cavity kill insect within day. In contrast, flies do not succumb to ingested for days even though some cross intestinal barrier into hemolymph hours. The mechanisms by which S. attacks enterocytes and damages epithelium remain uncharacterized. To better understand...

Abstract Acinetobacter baumannii can cause prolonged infections that disproportionately affect immunocompromised populations. Our understanding of A. respiratory pathogenesis relies on an acute murine infection model with limited clinical relevance employs unnaturally high number bacteria and requires the assessment bacterial load at 24-36 hours post-infection. Here, we demonstrate low intranasal inoculums in mice a tlr4 mutation leads to reduced inflammation, allowing for persistent lasting...

Abstract Multidrug-resistant Acinetobacter baumannii infections are increasing at alarming rates. Therefore, novel antibiotic-sparing treatments to combat these A. urgently needed. The development of interventions would benefit from a better understanding this bacterium’s pathobiology, which remains poorly understood. is regarded as an extracellular opportunistic pathogen. However, research on has largely focused common lab strains, such ATCC 19606, that have been isolated several decades...

Abstract Bacterial pneumonia is a common infection of the lower respiratory tract that can afflict patients all ages. Multidrug-resistant strains Acinetobacter baumannii are increasingly responsible for causing nosocomial pneumonias, thus posing an urgent threat. Alveolar macrophages play critical role in overcoming infections caused by this pathogen. Recently, we and others have shown new clinical isolates A. , but not lab strain ATCC 19606 (19606), persist replicate within spacious...