Faculty Opinions recommendation of A high-frequency phenotypic switch links bacterial virulence and environmental survival in Acinetobacter baumannii.

ABSTRACT Here, we report the isolation of 31 Acinetobacter baumannii strains producing OXA-253 in a single large Brazilian city. These strains belonged to five different sequence types (STs), including 4 STs not previously associated with bla OXA-253. In all strains, the bla OXA-253 gene was located in a plasmid within a genetic environment similar to what was found previously in Brazil and Italy. The reported data emphasize the successful transmission of the bla OXA-253 gene through a large area and the tendency for this resistance determinant to remain in the A. baumannii population.

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High-Frequency Rugose Exopolysaccharide Production by Vibrio cholerae

Applied and Environmental Microbiology ◽

10.1128/aem.68.11.5773-5778.2002 ◽

2002 ◽

Vol 68 (11) ◽

pp. 5773-5778 ◽

Cited By ~ 55

Author(s):

Afsar Ali ◽

Mohammed H. Rashid ◽

David K. R. Karaolis

Keyword(s):

Vibrio Cholerae ◽

High Frequency ◽

Biofilm Formation ◽

Colony Morphology ◽

Exopolysaccharide Production ◽

Clinical Strains ◽

Environmental Survival ◽

El Tor

ABSTRACT Vibrio cholerae can shift to a “rugose” phenotype, thereby producing copious exopolysaccharide (EPS), which promotes its environmental survival and persistence. We report conditions that promote high-frequency rugose EPS production (HFRP), whereby cells switch at high frequency (up to 80%) to rugose EPS production. HFRP appeared to be more common in clinical strains, as HFRP was found in 6 of 19 clinical strains (32%) (including classical, El Tor, and non-O1 strains) but in only 1 of 16 environmental strains (6%). Differences were found between strains in rugose colony morphology, conditions promoting HFRP, the frequency of rugose-to-smooth (R-S) cell reversion, and biofilm formation. We propose that rugose EPS and HFRP provide an evolutionary and adaptive advantage to specific epidemic V. cholerae strains for increased persistence in the environment.

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Acinetobacter baumannii Strains Deficient in the Clp Chaperone-Protease Genes Have Reduced Virulence in a Murine Model of Pneumonia

Pathogens ◽

10.3390/pathogens10020204 ◽

2021 ◽

Vol 10 (2) ◽

pp. 204

Author(s):

J Christian Belisario ◽

Hiu Ham Lee ◽

Harshani Luknauth ◽

Nathan W. Rigel ◽

Luis R. Martinez

Keyword(s):

Acinetobacter Baumannii ◽

Immune Cells ◽

Biofilm Formation ◽

Bacterial Virulence ◽

Mutant Library ◽

New Information ◽

Mutant Strains ◽

Irregular Cell ◽

And Function ◽

The Impact

Acinetobacter baumannii has emerged as a significant opportunistic Gram-negative pathogen and causative agent of nosocomial pneumonia especially in immunocompromised individuals in intensive care units. Recent advances to understand the contribution and function of A. baumannii virulence factors in its pathogenesis have begun to elucidate how this bacterium interacts with immune cells and its interesting mechanisms for multi-antibiotic resistance. Taking advantage of the availability of the A. baumannii AB5075 transposon mutant library, we investigated the impact of the A. baumannii Clp genes, which encode for a chaperone-protease responsible for the degradation of misfolded proteins, on bacterial virulence in a model of pneumonia using C57BL/6 mice and survival within J774.16 macrophage-like cells. Clp-protease A. baumannii mutants exhibit decreased virulence in rodents, high phagocytic cell-mediated killing and reduced biofilm formation. Capsular staining showed evidence of encapsulation in A. baumannii AB5075 and Clp-mutant strains. Surprisingly, clpA and clpS mutants displayed irregular cell morphology, which may be important in the biofilm structural deficiencies observed in these strains. Interestingly, clpA showed apical-like growth, proliferation normally observed in filamentous fungi. These findings provide new information regarding A. baumannii pathogenesis and may be important for the development of therapies intended at reducing morbidity and mortality associated with this remarkable pathogen.

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Antibiotic resistance assessment of Acinetobacter baumannii isolates from Tehran hospitals due to the presence of efflux pumps encoding genes (adeA and adeS genes) by molecular method

BMC Research Notes ◽

10.1186/s13104-020-05387-6 ◽

2020 ◽

Vol 13 (1) ◽

Author(s):

Batool Basatian-Tashkan ◽

Mohammad Niakan ◽

Mansoor Khaledi ◽

Hamed Afkhami ◽

Fatemeh Sameni ◽

...

Keyword(s):

Acinetobacter Baumannii ◽

High Frequency ◽

Efflux Pumps ◽

Diffusion Method ◽

Toxic Substances ◽

Mechanisms Of Resistance ◽

Molecular Method ◽

Disk Diffusion Method ◽

Pcr Method ◽

Encoding Genes

Abstract Objective Acinetobacter baumannii (A. baumannii) has caused many problems in nosocomial infections. Efflux pumps are considered as one of the most important mechanisms of resistance in this bacterium and have the ability to excrete toxic substances such as antibiotics out of the cell. Results In this study, 60 isolates of A. baumannii were collected from patients in several hospitals in Tehran, Iran. After diagnosis using standard biochemical methods, the pattern of antibiotic susceptibility was determined using the disk diffusion method according to CLSI guidelines. The adeA and adeS genes were identified by PCR method. The highest resistance to Piperacillin and the lowest resistance to Gentamicin were observed (100% compared to 48.4%). 6.6% of the isolates had only adeA gene and adeS gene was observed in 8.4% of isolates and both genes were detected in 73.4% of the samples. Despite the high resistance of t A. baumannii o antibiotics and due to the high frequency of genes of adeA and adeS efflux pumps in A. baumannii isolates, it can be concluded that these efflux pumps may play an important role in resistance of this bacterium. By determining the pattern of antibiotic the resistance before treatment, the resistance of this pathogen can be prevented in societies.

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Dual Role of gnaA in Antibiotic Resistance and Virulence in Acinetobacter baumannii

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00694-19 ◽

2019 ◽

Vol 63 (10) ◽

Cited By ~ 3

Author(s):

Qingye Xu ◽

Tao Chen ◽

Biyong Yan ◽

Linyue Zhang ◽

Borui Pi ◽

...

Keyword(s):

Acinetobacter Baumannii ◽

Capsular Polysaccharide ◽

Treatment Options ◽

Drug Susceptibility ◽

Multidrug Resistant ◽

Bacterial Virulence ◽

Content Type ◽

Evolution Experiment

ABSTRACT Acinetobacter baumannii is an important Gram-negative pathogen in hospital-related infections. However, treatment options for A. baumannii infections have become limited due to multidrug resistance. Bacterial virulence is often associated with capsule genes found in the K locus, many of which are essential for biosynthesis of the bacterial envelope. However, the roles of other genes in the K locus remain largely unknown. From an in vitro evolution experiment, we obtained an isolate of the virulent and multidrug-resistant A. baumannii strain MDR-ZJ06, called MDR-ZJ06M, which has an insertion by the ISAba16 transposon in gnaA (encoding UDP-N-acetylglucosamine C-6 dehydrogenase), a gene found in the K locus. The isolate showed an increased resistance toward tigecycline, whereas the MIC decreased in the case of carbapenems, cephalosporins, colistin, and minocycline. By using knockout and complementation experiments, we demonstrated that gnaA is important for the synthesis of lipooligosaccharide and capsular polysaccharide and that disruption of the gene affects the morphology, drug susceptibility, and virulence of the pathogen.

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