scholarly journals Antagonism and population dynamics of Acinetobacter baumannii from US military treatment centers

2017 ◽  
Author(s):  
Rae A Heitkamp ◽  
Amy M Zale ◽  
Benjamin C Kirkup
Keyword(s):  
Population Dynamics ◽  
Acinetobacter Baumannii ◽  
Bacterial Species ◽  
Hospital Setting ◽  
Antagonistic Activity ◽  
Resistant Bacteria ◽  
Natural Environments ◽  
Bacterial Populations ◽  
Starting Point ◽  
Before And After

Antibiotic-resistant bacteria complicate many infections and can be difficult to eradicate from hospitals. The population dynamics and ecology of these organisms in the hospital setting, however, is not well understood. Here, we report extensive strain-based antagonistic interactions occurring in military clinical isolates of Acinetobacter baumannii, a bacterial species that causes many drug-resistant hospital-associated infections. Sequence-based phylogenetic analysis of isolates allowed for differentiation to two major clades, with one of the clades representing two closely related genetic groups. Antagonistic activity was detected using a spot-plate assay to test pairwise interactions of all isolates. Isolates exhibited extensive and diverse patterns of antagonism against other isolates. One major clade of isolates had a distinct change in antagonism phenotype between isolates that differed by one base pair out of ~1500bp sequenced, with consistent antagonism of one group of isolates by the other. Both the antagonistic and the sensitive group exhibited extensive drug resistance. The first isolate of the antagonistic group was cultured in May 2010. The proportion of isolates from the antagonistic group collected before and after July 2010 increased from 2% to 76%. The results of this early study of the ecology of hospital-associated bacterial populations are discussed in the context of the species ecology of bacteria in natural environments. This work is a potential starting point for investigations into ecological interventions for infection control in hospitals.

scholarly journals Antagonism and population dynamics of Acinetobacter baumannii from US military treatment centers

2017 ◽  
Author(s):  
Rae A Heitkamp ◽  
Amy M Zale ◽  
Benjamin C Kirkup
Keyword(s):  
Population Dynamics ◽  
Acinetobacter Baumannii ◽  
Bacterial Species ◽  
Hospital Setting ◽  
Antagonistic Activity ◽  
Resistant Bacteria ◽  
Natural Environments ◽  
Bacterial Populations ◽  
Starting Point ◽  
Before And After

Antibiotic-resistant bacteria complicate many infections and can be difficult to eradicate from hospitals. The population dynamics and ecology of these organisms in the hospital setting, however, is not well understood. Here, we report extensive strain-based antagonistic interactions occurring in military clinical isolates of Acinetobacter baumannii, a bacterial species that causes many drug-resistant hospital-associated infections. Sequence-based phylogenetic analysis of isolates allowed for differentiation to two major clades, with one of the clades representing two closely related genetic groups. Antagonistic activity was detected using a spot-plate assay to test pairwise interactions of all isolates. Isolates exhibited extensive and diverse patterns of antagonism against other isolates. One major clade of isolates had a distinct change in antagonism phenotype between isolates that differed by one base pair out of ~1500bp sequenced, with consistent antagonism of one group of isolates by the other. Both the antagonistic and the sensitive group exhibited extensive drug resistance. The first isolate of the antagonistic group was cultured in May 2010. The proportion of isolates from the antagonistic group collected before and after July 2010 increased from 2% to 76%. The results of this early study of the ecology of hospital-associated bacterial populations are discussed in the context of the species ecology of bacteria in natural environments. This work is a potential starting point for investigations into ecological interventions for infection control in hospitals.

Dominant symbiotic bacteria associated with wild medfly populations reveal a bacteriocin-like killing phenotype: a ‘cold-case’ study

2019 ◽  
Vol 110 (4) ◽  
pp. 457-462
Author(s):  
Silvia Ciolfi ◽  
Laura Marri
Keyword(s):  
Bacterial Species ◽  
Klebsiella Oxytoca ◽  
Pcr Amplification ◽  
Fruit Trees ◽  
Antagonistic Activity ◽  
Culture Collection ◽  
Symbiotic Bacteria ◽  
Bacterial Populations

AbstractThe gut of the agricultural pest Ceratitis capitata hosts a varied community of bacteria, mainly Enterobacteriaceae, that were implicated in several processes that increase the fitness of the insect. In this study, we investigated the antagonistic activity in vitro of Klebsiella oxytoca strains isolated in the 1990s from the alimentary tract of wild medflies collected from different varieties of fruit trees at diverse localities. Assays were carried out against reference strains (representative of Gram-negative and -positive bacterial species) of the American Type Culture Collection (ATCC). Eight Klebsiella, out of 11, expressed a killing activity against Escherichia coli ATCC 23739, and Enterobacter cloacae ATCC 13047; among the eight strains, at least one showed activity against Salmonella typhimurium ATCC 23853. Genomic DNA derived from all Klebsiella strains was then subjected to PCR amplification using specific primer pairs designed from each of the four bacteriocin (KlebB, C, D, CCL) sequences found so far in Klebsiella. KlebD primer pairs were the only to produce a single product for all strains expressing the killing phenotype in vitro. One of the amplicons was cloned and sequenced; the DNA sequence shows 93% identity with a plasmid-carried colicin-D gene of a strain of Klebsiella michiganensis, and 86% identity with the sequence encoding for the klebicin D activity protein in K. oxytoca. Our work provides the first evidence that dominant symbiotic bacteria associated with wild medfly populations express a killing phenotype that may mediate inter and intraspecies competition among bacterial populations in the insect gut in vivo.

scholarly journals Dynamic Boolean modelling reveals the influence of energy supply on bacterial efflux pump expression

2021 ◽  
Author(s):  
Ryan Kerr ◽  
Sara Jabbari ◽  
Jessica M A Blair ◽  
Iain Johnston
Keyword(s):  
Gene Expression ◽  
Antimicrobial Resistance ◽  
Energy Supply ◽  
Regulatory Networks ◽  
Efflux Pump ◽  
Bacterial Species ◽  
Efflux Pumps ◽  
Resistant Bacteria ◽  
Energy Availability ◽  
Bacterial Populations

Antimicrobial resistance (AMR) is a global health issue. One key factor contributing to AMR is the ability of bacteria to export drugs through efflux pumps, which relies on the ATP-dependent expression and interaction of several controlling genes. Recent studies have shown significant cell-to-cell ATP variability exists within clonal bacterial populations, but the contribution of intrinsic cell-to-cell ATP heterogeneity is generally overlooked in understanding efflux pumps. Here, we consider how ATP variability influences gene regulatory networks controlling expression of efflux pump genes in two bacterial species. We develop and apply a generalisable Boolean modelling framework, developed to incorporate the dependence of gene expression dynamics on available cellular energy supply. Theoretical results show differences in energy availability can cause pronounced downstream heterogeneity in efflux gene expression. Cells with higher energy availability have a superior response to stressors. Further, in the absence of stress, model bacteria develop heterogeneous pulses of efflux pump gene expression which contribute to a sustained sub-population of cells with increased efflux expression activity, potentially conferring a continuous pool of intrinsically resistant bacteria. This modelling approach thus reveals an important source of heterogeneity in cell responses to antimicrobials and sheds light on potentially targetable aspects of efflux pump-related antimicrobial resistance.

scholarly journals Acquisition of a High Diversity of Bacteria during the Hajj Pilgrimage, Including Acinetobacter baumannii withblaOXA-72and Escherichia coli withblaNDM-5Carbapenemase Genes

2016 ◽  
Vol 60 (10) ◽  
pp. 5942-5948 ◽  
Author(s):  
Thongpan Leangapichart ◽  
Philippe Gautret ◽  
Karolina Griffiths ◽  
Khadidja Belhouchat ◽  
Ziad Memish ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Acinetobacter Baumannii ◽  
Rectal Swab ◽  
Multidrug Resistant ◽  
Resistant Bacteria ◽  
Pharyngeal Swab ◽  
Content Type ◽  
Carbapenemase Gene ◽  
Before And After ◽  
Pcr Targeting

ABSTRACTPilgrims returning from the Hajj (pilgrimage to Mecca) can be carriers of multidrug-resistant bacteria (MDR). Pharyngeal and rectal swab samples were collected from 98 pilgrims before and after they traveled to the Hajj in 2014 to investigate the acquisition of MDR bacteria. The bacterial diversity in pharyngeal swab samples was assessed by culture with selective media. There was a significantly higher diversity of bacteria in samples collected after the return from the Hajj than in those collected before (P= 0.0008). Surprisingly,Acinetobacter baumanniistrains were isolated from 16 pharyngeal swab samples (1 sample taken during the Hajj and 15 samples taken upon return) and 26 post-Hajj rectal swab samples, while none were isolated from samples taken before the Hajj. Testing of all samples by real-time PCR targetingblaOXA-51gave positive results for only 1% of samples taken during the Hajj, 21/90 (23.3%) pharyngeal swab samples taken post-Hajj, and 35/90 (38.9%) rectal swab samples taken post-Hajj. One strain ofA. baumanniiisolated from the pharynx was resistant to imipenem and harbored ablaOXA-72carbapenemase gene. Multilocus sequence typing analysis of 43A. baumanniiisolates revealed a huge diversity of 35 sequence types (STs), among which 18 were novel STs reported for the first time in this study. Moreover, we also found oneEscherichia coliisolate, collected from a rectal swab sample from a pilgrim taken after the Hajj, which harboredblaNDM-5,blaCTX-M-15,blaTEM-1, andaadA2(ST2659 and ST181). In conclusion, pilgrims are at a potential risk of acquiring and transmitting MDRAcinetobacterspp. and carbapenemase-producing Gram-negative bacteria during the Hajj season.

MODELING THE POPULATION DYNAMICS OF ANTIBIOTIC-RESISTANT BACTERIA: AN AGENT-BASED APPROACH

2009 ◽  
Vol 20 (03) ◽  
pp. 435-457 ◽  
Author(s):  
JAMES T. MURPHY ◽  
RAY WALSHE ◽  
MARC DEVOCELLE
Keyword(s):  
Population Dynamics ◽  
Pathogenic Bacteria ◽  
Cellular Level ◽  
Resistant Bacteria ◽  
Bacterial Cells ◽  
Theoretical Understanding ◽  
Bacterial Populations ◽  
Diverse Range ◽  
Agent Based ◽  
The Individual

The response of bacterial populations to antibiotic treatment is often a function of a diverse range of interacting factors. In order to develop strategies to minimize the spread of antibiotic resistance in pathogenic bacteria, a sound theoretical understanding of the systems of interactions taking place within a colony must be developed. The agent-based approach to modeling bacterial populations is a useful tool for relating data obtained at the molecular and cellular level with the overall population dynamics. Here we demonstrate an agent-based model, called Micro-Gen, which has been developed to simulate the growth and development of bacterial colonies in culture. The model also incorporates biochemical rules and parameters describing the kinetic interactions of bacterial cells with antibiotic molecules.Simulations were carried out to replicate the development of methicillin-resistant S. aureus (MRSA) colonies growing in the presence of antibiotics. The model was explored to see how the properties of the system emerge from the interactions of the individual bacterial agents in order to achieve a better mechanistic understanding of the population dynamics taking place. Micro-Gen provides a good theoretical framework for investigating the effects of local environmental conditions and cellular properties on the response of bacterial populations to antibiotic exposure in the context of a simulated environment.

scholarly journals In Situ Population Dynamics of Bacterial Viruses in a Terrestrial Environment

1999 ◽  
Vol 65 (1) ◽  
pp. 169-174 ◽  
Author(s):  
Kevin E. Ashelford ◽  
Martin J. Day ◽  
Mark J. Bailey ◽  
Andrew K. Lilley ◽  
John C. Fry
Keyword(s):  
Population Dynamics ◽  
Bacterial Species ◽  
Natural Environments ◽  
Terrestrial Environment ◽  
Peak Density ◽  
Serratia Liquefaciens ◽  
Temporal Succession ◽  
Bacterial Viruses ◽  
Phage Population

ABSTRACT Predation by bacteriophages is thought to control bacterial numbers and facilitate gene transfer among bacteria in the biosphere. A thorough understanding of phage population dynamics is therefore necessary if their significance in natural environments is to be fully appreciated. Here we describe the in situ population dynamics of three separate phage populations predating on separate bacterial species, living on the surface of field-grown sugar beet (Beta vulgaris var. Amethyst), as recorded over a 9-month period. The distributions of the three phage populations were different and fluctuated temporally in 1996 (peak density, ∼103 PFU g−1). One of these populations, predating on the indigenous phytosphere bacterium Serratia liquefaciens CP6, consisted of six genetically distinct DNA phages that varied in relative abundance to the extent that an apparent temporal succession was observed between the two most abundant phages, ΦCP6-1 and ΦCP6-4.

Synergistic Effect of Tazobactam on Amikacin MIC in Acinetobacter baumannii Isolated from Burn Patients in Tehran, Iran

2020 ◽  
Vol 21 (10) ◽  
pp. 997-1004
Author(s):  
Leila Azimi ◽  
Sahel V. Tahbaz ◽  
Reza Alaghehbandan ◽  
Farank Alinejad ◽  
Abdolaziz R. Lari
Keyword(s):  
Acinetobacter Baumannii ◽  
Inhibitory Concentration ◽  
Efflux Pump ◽  
Multidrug Resistant ◽  
Inhibitory Effect ◽  
Resistant Bacteria ◽  
High Morbidity ◽  
Burn Patients ◽  
Global Public Health ◽  
Before And After

Background: Burn is still an important global public health challenge. Wound colonization of antibiotic resistant bacteria such as Acinetobacter baumannii can lead to high morbidity and mortality in burn patients. The aim of this study was to evaluate the inhibitory effect of tazobactam on efflux pump, which can cause aminoglycoside resistant in A. baumannii isolated from burn patients. Methods: In this study, 47 aminoglycoside resistant A. baumannii spp. were obtained from burn patients, admitted to the Shahid Motahari Burns Hospital in Tehran, Iran, during June-August 2018. The inhibitory effect of tazobactam against adeB such as efflux pump was evaluated by Minimum Inhibitory Concentration (MIC) determination of amikacin alone and in combination with tazobactam. Fractional Inhibitory Concentration index (FIC) was used to determine the efficacy of tazobactam/ amikacin combination. Further, semi-quantitative Real- Time PCR was performed to quantify the expression rates of the adeB gene before and after addition of tazobactam/amikacin. Results: The MIC values were significantly reduced when a combined amikacin and tazobactam was utilized. The most common interaction observed was synergistic (78.2%), followed by additive effects (21.8%), as per FIC results. The adeB mRNA expression levels were found to be downregulated in 60.7% of isolates treated with tazobactam. Conclusions: Tazobactam can have impact on resistance to aminoglycoside by inhibiting efflux pump. Thus, the combination of tazobactam with amikacin can be used as an alternative treatment approach in multidrug resistant A. baumannii infections.

On The Necessity to Study Natural Bacterial Populations-The Model of Bacillus Simplex From "Evolution Canyons" I and II, Israel

2006 ◽  
Vol 52 (3-4) ◽  
pp. 527-542 ◽  
Author(s):  
Johannes Sikorski ◽  
Eviatar Nevo
Keyword(s):  
Bacterial Species ◽  
Natural Populations ◽  
Natural Environments ◽  
Natural Habitats ◽  
Bacterial Populations ◽  
Bacillus Simplex ◽  
Evolution Canyon ◽  
Bacterial Systematics ◽  
Taxon Identification ◽  
Insight Into

How do bacteria evolve and speciate in natural environments? How does bacterial evolution relate to bacterial systematics? Exploring these answers is essential because bacteria profoundly impact life in general and, in particular, that of humans. Much insight into bacterial microevolution has come from theoretical and computational studies and from multigenerational laboratory systems ("Experimental Evolution"). These studies, however, do not take into account the diversity of modes of how bacteria can evolve under the complexity of the real world, i.e., nature. We argue, therefore, that for a comprehensive understanding of bacterial microevolution, it is essential to study natural populations. We underline our argument by introducing the Bacillus simplex model from "Evolution Canyon", Israel. This metapopulation splits into different evolutionary lineages that have adapted to the microclimatically different slopes of "Evolution Canyon". It was shown that temperature stress is a major environmental factor driving the B. simplex adaptation and speciation progress. Therefore, this model population has proven highly suitable to study bacterial microevolution in natural habitats. Finally, we discuss the B. simplex intrapopulation divergence of lineages in light of current controversies on bacterial species concepts and taxon identification.

scholarly journals Antagonistic Activity of Bacteria Isolated from the Periplaneta americana L. Gut against Some Multidrug-Resistant Human Pathogens

Antibiotics ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 294
Author(s):  
Asmaa Amer ◽  
Basma Hamdy ◽  
Dalia Mahmoud ◽  
Mervat Elanany ◽  
Magda Rady ◽  
...  
Keyword(s):  
Periplaneta Americana ◽  
Bacterial Species ◽  
Pathogenic Fungi ◽  
Multidrug Resistant ◽  
Antagonistic Activity ◽  
Gut Bacteria ◽  
American Cockroach ◽  
Resistant Bacteria ◽  
Human Pathogens ◽  
Wide Range

The insect gut is home to a wide range of microorganisms, including several bacterial species. Such bacterial symbionts provide various benefits to their insect hosts. One of such services is providing metabolites that resist infections. Little data are available about gut-inhabiting bacteria for several insect groups. Through the present work, the gut bacteria associated with the American cockroach (Periplaneta americana L.) were isolated, identified, and studied for their potential antimicrobial activity against multidrug-resistant (MDR) human pathogens. The cockroaches were collected from three different environmental sites. Gut bacteria were isolated, and sixteen species of bacteria were identified using Vitek MALDI-TOF MS. The antagonistic activity of the identified bacteria was tested against a panel of multidrug-resistant bacteria and fungi, namely: methicillin-resistant Staphylococcus aureus (MRSA) (clinical isolate), Streptococcus mutans Clarke (RCMB 017(1) ATCC ® 25175™) (Gram-positive bacteria), Enterobacter cloacae (RCMB 001(1) ATCC® 23355™) and Salmonella enterica (ATCC® 25566™) (Gram-negative bacteria). The isolates were also tested against human pathogenic fungi such as Candida albicans (RCMB005003(1) ATCC® 10231™), Aspergillus niger (RCMB002005), Aspergillus fumigatus (RCMB002008), Aspergillus flavus (RCMB002002), and Penicillium italicum (RCMB 001018(1) IMI193019). The results indicated that some bacterial species from the cockroach gut could antagonize the growth activity of all the tested pathogens. Such antimicrobial properties could ultimately lead to the future development of therapeutic drugs. The evaluation and mode of action of antagonistic gut bacteria against the most affected MDR pathogens were demonstrated using transmission electron microscopy (TEM).

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