Surveying a Swarm: Experimental Techniques to Establish and Examine Bacterial Collective Motion

Author(s):  
Jonathan D. Partridge

The survival and successful spread of many bacterial species hinges on their mode of motility. One of the most distinct of these is swarming, a collective form of motility where a dense consortium of bacteria employ flagella to propel themselves across a solid surface. Surface environments pose unique challenges, derived from higher surface friction/tension and insufficient hydration. Bacteria have adapted by deploying an array of mechanisms to overcome these challenges. Beyond allowing bacteria to colonize new terrain in the absence of bulk liquid, swarming also bestows faster speeds and enhanced antibiotic resistance to the collective. These crucial attributes contribute to the dissemination, and in some cases pathogenicity, of an array of bacteria. This mini-review highlights; 1) aspects of swarming motility that differentiates it from other methods of bacterial locomotion. 2) Facilitatory mechanisms deployed by diverse bacteria to overcome different surface challenges. 3) The (often difficult) approaches required to cultivate genuine swarmers. 4) The methods available to observe and assess the various facets of this collective motion, as well as the features exhibited by the population as a whole.

2021 ◽  
Vol 6 (2) ◽  
pp. 56
Author(s):  
Bijendra Raj Raghubanshi ◽  
Karuna D. Sagili ◽  
Wai Wai Han ◽  
Henish Shakya ◽  
Priyanka Shrestha ◽  
...  

Globally, antibiotic resistance in bacteria isolated from neonatal sepsis is increasing. In this cross-sectional study conducted at a medical college teaching hospital in Nepal, we assessed the antibiotic resistance levels in bacteria cultured from neonates with sepsis and their in-hospital treatment outcomes. We extracted data of neonates with sepsis admitted for in-patient care from June 2018 to December 2019 by reviewing hospital records of the neonatal intensive care unit and microbiology department. A total of 308 neonates with sepsis were admitted of which, blood bacterial culture antibiotic sensitivity reports were available for 298 neonates. Twenty neonates (7%) had bacteriologic culture-confirmed neonatal sepsis. The most common bacterial species isolated were Staphylococcus aureus (8), followed by coagulase-negative Staphylococcus (5). Most of these bacteria were resistant to at least one first-line antibiotic used to manage neonatal sepsis. Overall, there were 7 (2%) deaths among the 308 neonates (none of them from the bacterial culture-positive group), and 53 (17%) neonates had left the hospital against medical advice (LAMA). Improving hospital procedures to isolate bacteria in neonates with sepsis, undertaking measures to prevent the spread of antibiotic-resistant bacteria, and addressing LAMA’s reasons are urgently needed.


2021 ◽  
Vol 41 ◽  
Author(s):  
Antonio Jackson F. Beleza ◽  
William Cardoso Maciel ◽  
Arianne S. Carreira ◽  
Adson R. Marques ◽  
Fabio P. Nunes ◽  
...  

ABSTRACT: The grey-breasted parakeet (Pyrrhura griseipectus) is an endangered psittacine species that have been affected by illegal trade and deforestation. Currently, this endemic species is only found in three areas in Ceará state, in Brazil. This study aimed to investigate the frequency and diversity of Enterobacteriaceae in wild adult grey-breasted parakeets and determine their susceptibility to antimicrobial agents. Cloacal swab samples were collected from 27 individuals and environmental swabs (drag swabs) from five nests used by these birds. Twenty-seven strains from nine species of Enterobacteriaceae were recovered from cloacal swabs, and the most prevalent bacteria strains were Hafnia alvei (22%) and Pantoea agglomerans (22%). From environmental nest samples, seven strains from three bacterial species were isolated, being the P. agglomerans the most frequent species (100%). Twenty-two of the 27 isolates (81.4%) exhibited antibiotic resistance, varying from one to eight of the 12 antimicrobials commonly used. Resistance to amoxicillin was the most prevalent (70.4%), followed by azithromycin (22.2%) and ceftriaxone (18.5%). None of the strains were resistant to gentamicin, tobramycin, ciprofloxacin or tetracycline. The H. alvei was the main species presenting multidrug resistance, including resistance against meropenem, which is an important finding. These results could provide interesting information on the health of these endangered wild grey-breasted parakeets. They could also indicate that the obtained isolates are part of a group of bacteria that are typical components of the enteric microbiota of birds, which present elevated rates of resistance to amoxicillin.


Author(s):  
Nadia Al-Shammari

Opportunistic bacteria are microorganisms that have been isolated from a host suffering from stress as a result of parasitic infestation. In this study, two bacterial species, namely Aeromonas hydrophila and Rhizobium radiobacter, were isolated from Trypauchen vagina fish that were infected with Microsporidian parasite cysts from Iraqi marine waters. The infection were mass implanted in the internal and external skeletal muscles and under the gill cover. Many symptoms of bacterial infection were observed in the fish, including flatulence with haemorrhagic fluids, skin disscolouration blackening, separation of crusts, and deformities in the area. The two bacterial species were characterised morphologically and identified using Vitek II system (Biomerieux - USA). To control infection, antibiotic susceptibility was performed using six antibiotics: nalidixic acid, nitrofurantoin, gentamicin, streptomycin, tetracycline and amoxicillin, both bacteria showed high antibiotic resistance. Identification of opportunistic bacteria has a pivotal role in preventing stress factors in fish, treating infections and alleviating their impact on other aquatic organisms.


Author(s):  
D.J. Vatalia ◽  
B.B. Bhanderi ◽  
V.R. Nimavat ◽  
M.K. Jhala

Background: Mastitis, the inflammation of parenchyma of mammary gland is frequently considered to be costliest and complex disease prevalent in India. Mastitis is caused by pathogens like Staphylococcus spp., Streptococcus spp., Mycoplasma bovis, E. coli, Klebsiella spp., Citrobacter spp., Enterobacter spp. and Entercoccus. The treatment of mastitis in animals is carried out using antibiotics. Treatment failure in mastitis is due to increased antibiotic resistance of mastitis pathogens and also due to indiscriminate use of antibiotics without testing in vitro antibiotic sensitivity test against causal organisms. In comparison to cultural method, PCR assays takes less time for detection of bacteria from the mastitis milk samples. Present research work was carried out regarding isolation, identification and multiple drug resistance profile of clinical bovine mastitis associated pathogens using conventional as well as molecular approach. Methods: In the present study, 73 mastitis milk samples were collected from Anand and Panchmahal district of Gujarat. The milk samples were subjected for cultural isolation and DNA extraction for identification of bacteria by cultural and PCR method. Antimicrobial sensitivity pattern of the isolates were carried by disc diffusion method and isolates were categorized in multiple drug resistant. Result: In the present study, Out of 73 mastitis milk samples collected from cows 48 (65.75%) cows were positive for bacterial isolation and S. aureus was the most predominant bacterial species. PCR from the mastitis milk additionally detected bacteria in culturally negative milk samples. Most sensitive drug was gentamicin and most of the isolates (90.19%) showed the multiple drug resistance for the two to nine drugs with 0.1 to 0.6 multiple antibiotic resistance index.


2018 ◽  
Author(s):  
Mohammed Alorabi ◽  
Aisha M. AlAmri ◽  
Yuiko Takebayashi ◽  
Kate J. Heesom ◽  
Matthew B. Avison

AbstractThe mobile antibiotic resistance gene blaIMP-1 is clinically important and has a synonymous AAA:AAG lysine codon usage bias of 73:27. This bias is like that seen in experimentally determined highly expressed genes in Escherichia coli and Acinetobacter baumanii, but quite different from that seen in Pseudomonas aeruginosa (26:74 AAA:AAG). Here we show that, paradoxically, shifting the AAA:AAG lysine codon bias to 8:92 in blaIMP-1 expressed from a natural promoter results in significantly more IMP-1 production in all three species. Sequential site directed mutagenesis revealed that increased IMP-1 production occurs following removal of an AAA,AAA double lysine codon and that otherwise, lysine codon usage had no observable impact on IMP-1 production. We conclude that ribosomal slippage at this poly-adenosine region reduces efficient translation of IMP-1 and that punctuating the region with guanine reduces ribosomal slippage and increases IMP-1 production.


2017 ◽  
Vol 199 (18) ◽  
Author(s):  
Reed M. Stubbendieck ◽  
Paul D. Straight

ABSTRACT Bacteria use two-component signaling systems to adapt and respond to their competitors and changing environments. For instance, competitor bacteria may produce antibiotics and other bioactive metabolites and sequester nutrients. To survive, some species of bacteria escape competition through antibiotic production, biofilm formation, or motility. Specialized metabolite production and biofilm formation are relatively well understood for bacterial species in isolation. How bacteria control these functions when competitors are present is not well studied. To address fundamental questions relating to the competitive mechanisms of different species, we have developed a model system using two species of soil bacteria, Bacillus subtilis and Streptomyces sp. strain Mg1. Using this model, we previously found that linearmycins produced by Streptomyces sp. strain Mg1 cause lysis of B. subtilis cells and degradation of colony matrix. We identified strains of B. subtilis with mutations in the two-component signaling system yfiJK operon that confer dual phenotypes of specific linearmycin resistance and biofilm morphology. We determined that expression of the ATP-binding cassette (ABC) transporter yfiLMN operon, particularly yfiM and yfiN, is necessary for biofilm morphology. Using transposon mutagenesis, we identified genes that are required for YfiLMN-mediated biofilm morphology, including several chaperones. Using transcriptional fusions, we found that YfiJ signaling is activated by linearmycins and other polyene metabolites. Finally, using a truncated YfiJ, we show that YfiJ requires its transmembrane domain to activate downstream signaling. Taken together, these results suggest coordinated dual antibiotic resistance and biofilm morphology by a single multifunctional ABC transporter promotes competitive fitness of B. subtilis. IMPORTANCE DNA sequencing approaches have revealed hitherto unexplored diversity of bacterial species in a wide variety of environments that includes the gastrointestinal tract of animals and the rhizosphere of plants. Interactions between different species in bacterial communities have impacts on our health and industry. However, many approaches currently used to study whole bacterial communities do not resolve mechanistic details of interspecies interactions, including how bacteria sense and respond to their competitors. Using a competition model, we have uncovered dual functions for a previously uncharacterized two-component signaling system involved in specific antibiotic resistance and biofilm morphology. Insights gleaned from signaling within interspecies interaction models build a more complete understanding of gene functions important for bacterial communities and will enhance community-level analytical approaches.


Author(s):  
Sophia Inbaraj ◽  
Vamshi Krishna Sriram ◽  
Prasad Thomas ◽  
Abhishek Verma ◽  
Pallab Chaudhuri

Antibiotic resistance is an emerging threat to achieving one health all over the globe. The phenomenon leads to the emergence of drug-resistant microbes previously susceptible to an antibiotic. Drug-resistant microbes are the major reasons for medical complications like patient mortality and treatment failure. Unregulated use of antibiotics in animal husbandry is one of the major reasons for the emergence of antibiotic resistance. The resistance enters the human population mainly through the food chain. The genetic markers associated with drug resistance spread among different bacterial species by horizontal gene transfer mechanisms. Therefore, regulation of antibiotics use in animal husbandry and proper safety measures at farm level are necessary to check drug-resistant microbes entering the food chain. This chapter discusses the antibiotics, antibiotic resistance, genetic mechanisms involved, the spread of resistance, and also the available strategies to combat antimicrobial drug resistance.


mSystems ◽  
2020 ◽  
Vol 5 (3) ◽  
Author(s):  
Teresa Gil-Gil ◽  
Fernando Corona ◽  
José Luis Martínez ◽  
Alejandra Bernardini

ABSTRACT Fosfomycin is a bactericidal antibiotic, analogous to phosphoenolpyruvate, that exerts its activity by inhibiting the activity of MurA. This enzyme catalyzes the first step of peptidoglycan biosynthesis, the transfer of enolpyruvate from phosphoenolpyruvate to uridine-diphosphate-N-acetylglucosamine. Fosfomycin is increasingly being used, mainly for treating infections caused by Gram-negative multidrug-resistant bacteria. The mechanisms of mutational resistance to fosfomycin in Stenotrophomonas maltophilia, an opportunistic pathogen characterized by its low susceptibility to commonly used antibiotics, were studied in the current work. None of the mechanisms reported so far for other organisms, which include the production of fosfomycin-inactivating enzymes, target modification, induction of an alternative peptidoglycan biosynthesis pathway, and the impaired entry of the antibiotic, are involved in the acquisition of such resistance by this bacterial species. Instead, the unique cause of resistance in the mutants studied is the mutational inactivation of different enzymes belonging to the Embden-Meyerhof-Parnas central metabolism pathway. The amount of intracellular fosfomycin accumulation did not change in any of these mutants, showing that neither inactivation nor transport of the antibiotic is involved. Transcriptomic analysis also showed that the mutants did not present changes in the expression level of putative alternative peptidoglycan biosynthesis pathway genes or any related enzyme. Finally, the mutants did not present an increased phosphoenolpyruvate concentration that might compete with fosfomycin for its binding to MurA. On the basis of these results, we describe a completely novel mechanism of antibiotic resistance based on mutations of genes encoding metabolic enzymes. IMPORTANCE Antibiotic resistance has been largely considered a specific bacterial response to an antibiotic challenge. Indeed, its study has been mainly concentrated on mechanisms that affect the antibiotics (mutations in transporters, efflux pumps, and antibiotic-modifying enzymes, or their regulators) or their targets (i.e., target mutations, protection, or bypass). Usually, antibiotic resistance-associated metabolic changes were considered a consequence (fitness costs) and not a cause of antibiotic resistance. Herein, we show that alterations in the central carbon bacterial metabolism can also be the cause of antibiotic resistance. In the study presented here, Stenotrophomonas maltophilia acquires fosfomycin resistance through the inactivation of glycolytic enzymes belonging to the Embden-Meyerhof-Parnas pathway. Besides resistance to fosfomycin, this inactivation also impairs the bacterial gluconeogenic pathway. Together with previous work showing that antibiotic resistance can be under metabolic control, our results provide evidence that antibiotic resistance is intertwined with the bacterial metabolism.


2013 ◽  
Vol 6 (1) ◽  
pp. 125-131 ◽  
Author(s):  
S. Silambarasan ◽  
J. Abraham

Metal pollution is a growing problem and microbes have adapted to tolerate the presence of metals and even use them. The investigation was carried out to screen for bisorption property of metals by bacteria and check for correlation between tolerance to heavy metals and antibiotic resistance. Soil samples were collected from Palar River basin site of Vellore and five distinct bacteria were isolated. Antibiotic resistance (bacitracin, chloramphenicol, streptomycin, rifampicin, penicillin and ampicillin) was checked and tolerance to heavy metals was screened (Cd, Pb, Cu and Zn). It was found that most of the bacterial isolates had multiple antibiotic resistances which might be due to the stress caused by heavy metals released into the Palar river basin, Vellore. The multiple antibiotics resistance of this bacterial species was found to be associated with tolerance to metals. Biosorption studies revealed that Alcaligenes faecalis could tolerate 59% Cd, 61% Pb, 40% Cu, 39% Zn and Staphylococcus aureus removed 60% Cd, 63% Pb, 42% Cu, 41% Zn and Streptococcus lactis absorbed 61% Cd, 57% Pb, 37% Cu, 38% Zn and Micrococcus luteus reduced 56% Cd, 61% Pb, 39% Cu, 41% Zn and Enterobacter aerogenes removed 60% Cd, 55% Pb, 62% Cu, 67% Zn. Keywords: Antibiotic resistant; Heavy metal tolerance; Biosorption; Metal polluted soils. © 2014 JSR Publications. ISSN: 2070-0237 (Print); 2070-0245 (Online). All rights reserved. doi: http://dx.doi.org/10.3329/jsr.v6i1.14678 J. Sci. Res. 6 (1), 125-131 (2014)      


2019 ◽  
Author(s):  
Saida Benomar ◽  
Kara C Evans ◽  
Robert L Unckless ◽  
Josephine R Chandler

ABSTRACTVery little is known of the antibiotic resistance mechanisms of members of theChromobacteriumgenus. In previous studies ofChromobacterium subtsugae(formerlyC. violaceum) strain CV017, we identified a resistance nodulation division (RND)-family efflux pump (CdeAB-OprM). Here, we show thecdeAB-oprMgenes are widely distributed in members of theChromobacteriumgenus. We use antimicrobial susceptibility testing with a CV017cdeAB-oprMmutant to show the products of these genes confers resistance to a variety of antibiotics including ciprofloxacin, a clinically important antibiotic. We also identified a related RND-family pump,cseAB-oprN, in the genome of CV017 and otherC. subtsugaespecies, that is not present in other members of theChromobacteriumgenus. We demonstrate that CdeAB-OprM and CseAB-OprN are both transcriptionally induced in CV017 cells treated with sub-lethal antibiotic concentrations and they are important for induction of tolerance to different antibiotics. While CdeAB-OprM has a broad antibiotic specificity, the CseAB-OprN system is highly specific for a ribosome-targeting antibiotic produced by the saprophytic bacteriumBurkholderia thailandensis,bactobolin. Finally, we use a previously developedB. thailandensis-C. subtsugaeCV017 co-culture model to demonstrate that adding sub-lethal bactobolin at the beginning of co-culture growth increases the ability of CV017 to compete withB. thailandensisin a manner that is dependent on the CseAB-OprN system. Our results provide new information on the antibiotic resistance mechanisms ofChromobacteriumspecies and highlight the importance of efflux pumps during competition with other bacterial species.IMPORTANCEThis study describes two closely related efflux pumps in members of theChromobacteriumgenus, which includes opportunistic but often-fatal pathogens and species with highly versatile metabolic capabilities. Efflux pumps remove antibiotics from the cell and are important for antibiotic resistance. One of these pumps is broadly distributed in theChromobacteriumgenus and increases resistance to clinically relevant antibiotics. The other efflux pump is present only inChromobacterium subtsugaeand is highly specific for bactobolin, an antibiotic produced by the soil saprophyteBurkholderia thailandensis. We demonstrate these pumps can be activated to increase resistance by their antibiotic substrates, and that this activation is important forC. subtsugaeto survive in a laboratory competition experiment withB. thailandensis.These results have implications for managing antibiotic-resistantChromobacteriuminfections, bioengineering ofChromobacteriumspecies, and for understanding the evolution of efflux pumps.


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