scholarly journals The Comparative Virulence of Francisella tularensis Subsp. mediasiatica for Vaccinated Laboratory Animals

2020 ◽  
Vol 8 (9) ◽  
pp. 1403 ◽  
Author(s):  
Vitalii Timofeev ◽  
Galina Titareva ◽  
Irina Bahtejeva ◽  
Tatiana Kombarova ◽  
Tatiana Kravchenko ◽  
...  
Keyword(s):  
Infectious Disease ◽  
Central Asia ◽  
Present Article ◽  
Francisella Tularensis ◽  
Guinea Pigs ◽  
Laboratory Animals ◽  
Gram Negative Bacteria ◽  
Tularensis Subsp ◽  
Gram Negative ◽  
Virulent Strains

Tularemia is a severe infectious disease caused by the Gram-negative bacteria Fracisella tularensis. There are four subspecies of F.tularensis: holarctica, tularensis, mediasiatica, and novicida, which differ in their virulence and geographic distribution. One of them, subsp. mediasiatica remains extremely poorly studied, primarily due to the fact that it is found only in the sparsely populated regions of Central Asia and Russia. In particular there is little information in the literature on the virulence and pathogenicity of subsp. mediasiatica. In the present article, we evaluated the comparative virulence of subsp. mediasiatica in vaccinated laboratory animals which we infected with virulent strains: subsp. mediasiatica 678, subsp. holarctica 503, and subsp. tularensis SCHU within 60 to 180 days after vaccination. We found that subsp. mediasiatica is comparable in pathogenicity in mice with subsp. tularensis and in guinea pigs with subsp. holarctica. We also found that the live vaccine does not fully protect mice from subsp. mediasiatica but completely protects guinea pigs for at least six months. In general, our data suggest that subsp. mediasiatica occupies an intermediate position in virulence between spp. tularensis and holarctica.

scholarly journals Insights into Newer Antimicrobial Agents against Gram-negative Bacteria

2016 ◽  
Vol 9 ◽  
pp. MBI.S29459 ◽  
Author(s):  
Neelam Yaneja ◽  
Harsimran Kaur
Keyword(s):  
Infectious Disease ◽  
Antimicrobial Agents ◽  
Gram Negative Bacteria ◽  
Acinetobacter Species ◽  
Gram Negative ◽  
Limited Availability ◽  
The Past ◽  
Pseudomonas Species ◽  
Important Challenge ◽  
Novel Antibiotics

Currently, drug resistance, especially against cephalosporins and carbapenems, among gram-negative bacteria is an important challenge, which is further enhanced by the limited availability of drugs against these bugs. There are certain antibiotics (colistin, fosfomycin, temocillin, and rifampicin) that have been revived from the past to tackle the menace of superbugs, including members of Enterobacteriaceae, Acinetobacter species, and Pseudomonas species. Very few newer antibiotics have been added to the pool of existing drugs. There are still many antibiotics that are passing through various phases of clinical trials. The initiative of Infectious Disease Society of America to develop 10 novel antibiotics against gram-negative bacilli by 2020 is a step to fill the gap of limited availability of drugs. This review aims to provide insights into the current and newer drugs in pipeline for the treatment of gram-negative bacteria and also discusses the major challenging issues for their management.

scholarly journals Identification of LpxL, a Late Acyltransferase of Francisella tularensis

2007 ◽  
Vol 75 (11) ◽  
pp. 5518-5531 ◽  
Author(s):  
Molly K. McLendon ◽  
Birgit Schilling ◽  
Jason R. Hunt ◽  
Michael A. Apicella ◽  
Bradford W. Gibson
Keyword(s):  
Francisella Tularensis ◽  
Lipid A ◽  
Structural Features ◽  
Spectrometric Analysis ◽  
Temperature Sensitive ◽  
Gram Negative Bacteria ◽  
Dependent Manner ◽  
Gram Negative ◽  
Acyl Chains

ABSTRACT Lipopolysaccharide (LPS) is a major component of the outer membrane of gram-negative bacteria, and the lipid A region of LPS mediates stimulation of the immune system in a structure-dependent manner. Unlike the LPS of many other gram-negative bacteria, the LPS of Francisella tularensis isolated from in vitro cultures is not proinflammatory. This observed lack of proinflammatory prowess may reflect structural features of the lipid A, such as the number and length of the acyl chains and the single-phosphate group. To better understand this phenotype, we have begun to elucidate LPS biosynthesis in F. tularensis. We present complementation, mutational, and chemical data demonstrating that F. tularensis FTT0232c encodes a functional late acyltransferase enzyme with specificity similar to that of the Escherichia coli LpxL ortholog. Expression of this late acyltransferase complemented the temperature-sensitive and hypoacylated lipid A phenotypes of an E. coli lpxL mutant, expression of FTT0232c is increased during intracellular growth relative to that during in vitro growth, and finally, LPS obtained from a mutant of F. tularensis lacking FTT0232c showed an abundant triacyl lipid A species after mass spectrometric analysis, consistent with the loss of an LpxL late acyltransferase.

Gram-Negative Peritonitis—The Achilles Heel of Peritoneal Dialysis?

2007 ◽  
Vol 27 (2_suppl) ◽  
pp. 267-271 ◽  
Author(s):  
Cheuk-Chun Szeto ◽  
Kai-Ming Chow
Keyword(s):  
Antibiotic Resistance ◽  
Peritoneal Dialysis ◽  
Medical Treatment ◽  
Present Article ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Recent Advances

Peritonitis caused by gram-negative bacteria is a serious complication of peritoneal dialysis. Antibiotic resistance is common, and response to medical treatment is often poor. In the present article, we review recent advances in the understanding of the pathogenesis and treatment of this serious condition.

scholarly journals Melioidosis: a case series from coastal Karnataka, India

2019 ◽  
Vol 7 (10) ◽  
pp. 3920
Author(s):  
Shabari M. Shenoy ◽  
Ankith Vaidya ◽  
Chethan Subramanya
Keyword(s):  
Infectious Disease ◽  
South India ◽  
Tertiary Care Hospital ◽  
Tertiary Care ◽  
Case Series ◽  
Gram Negative Bacteria ◽  
Care Hospital ◽  
Gram Negative ◽  
Coastal City ◽  
Sporadic Cases

Melioidosis is an infectious disease caused by gram negative bacteria B. pseudomallei. The disease is largely under diagnosed globally. Sporadic cases have been reported from India, distributed mostly in the coastal areas. Authors present a series of seven culture proven cases of Melioidosis treated at a tertiary care Hospital in the coastal city of Mangalore in South India.

scholarly journals Carotenoids and Periodontal Infection

Nutrients ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 269
Author(s):  
Koji Naruishi
Keyword(s):  
Diabetes Mellitus ◽  
Infectious Disease ◽  
Blood Stream ◽  
The Other ◽  
Low Grade ◽  
Gram Negative Bacteria ◽  
Systemic Diseases ◽  
Gram Negative ◽  
Periodontal Infection ◽  
Novel Strategy

Periodontitis is a polymicrobial infectious disease that leads to inflammation of the gingiva, resulting in teeth loss by various causes such as inflammation-mediated bone resorption. Recently, many investigators have reported that the periodontitis resulting from persistent low-grade infection of Gram-negative bacteria such as Porphyromonas gingivalis (Pg) is associated with increased atherosclerosis, diabetes mellitus, and other systemic diseases through blood stream. On the other hand, carotenoids belong among phytochemicals that are responsible for different colors of the foods. It is important to examine whether carotenoids are effective to the inhibition of periodontal infection/inflammation cascades. This review summarizes the advanced state of knowledge about suppression of periodontal infection by several carotenoids. A series of findings suggest that carotenoids intake may provide novel strategy for periodontitis treatment, although further study will be needed.

scholarly journals The conglutination phenomenon: X. Conglutinin and immuno-conglutinin in guinea-pigs, pigs, donkeys, rats and mice

1954 ◽  
Vol 52 (4) ◽  
pp. 534-544 ◽  
Author(s):  
Anne M. Coombs
Keyword(s):  
Intravenous Injection ◽  
Guinea Pigs ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Rats And Mice

1. Immuno-conglutinin production by auto-stimulation was attempted in guinea-pigs, pigs, donkeys, rats and mice by the intravenous injection of a suspension of Gram-negative bacteria. The attempt was successful in rats and mice.2. Experiments were carried out to elucidate the lack of response in guinea-pigs.The author would like to thank Mr N. H. Hole of the Ministry of Agriculture Veterinary Laboratories at Weybridge, who inoculated and bled the donkeys used in these experiments.

scholarly journals Optimized MALDI TOF Mass Spectrometry Identification of Francisella tularensis Subsp. holarctica

2020 ◽  
Vol 8 (8) ◽  
pp. 1143
Author(s):  
Sofiane Regoui ◽  
Aurélie Hennebique ◽  
Thomas Girard ◽  
Sandrine Boisset ◽  
Yvan Caspar ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Francisella Tularensis ◽  
Healthcare Management ◽  
Accurate Identification ◽  
Tularensis Subsp ◽  
Gram Negative ◽  
Maldi Tof Mass Spectrometry ◽  
Human Samples ◽  
Maldi Tof ◽  
Mass Spectrometry Identification

Francisella tularensis is a tier 1 agent causing the zoonosis tularemia. This highly infectious Gram-negative bacterium is occasionally isolated from human samples (especially blood samples) in routine clinical microbiology laboratories. A rapid and accurate method for identifying this pathogen is needed in order to optimize the infected patient’s healthcare management and prevent contamination of the laboratory personnel. MALDI TOF mass spectrometry has become the gold standard for the rapid identification of most human pathogens. However, F. tularensis identification using such technology and commercially available databases is currently considered unreliable. Real-time PCR-based methods for rapid detection and accurate identification of F. tularensis are not available in many laboratories. As a national reference center for tularemia, we developed a MALDI TOF database allowing accurate identification of the species F. tularensis and its differentiation from the closely related neighbor species F. tularensis subsp. novicida and F. philomiragia. The sensitivity and specificity of this database were validated by testing 71 F. tularensis strains and 165 strains from 63 species not belonging to the Francisella genus. We obtained accurate identification at the species level and differentiation of all the tested bacterial strains. In particular, F. tularensis could be accurately differentiated from other small Gram-negative bacilli occasionally isolated from human samples, including species of the HACEK group and Brucella melitensis.

Comparison of Enrichment and Plating Media for Recovery of Virulent Strains of Yersinia enterocolitica from Inoculated Beef Stew

1983 ◽  
Vol 46 (11) ◽  
pp. 957-964 ◽  
Author(s):  
D. A. SCHIEMANN
Keyword(s):  
Yersinia Enterocolitica ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Selective Enrichment ◽  
Serotype O ◽  
Virulent Strains ◽  
Different Temperatures ◽  
Pure Cultures ◽  
Agar Media ◽  
Quantitative Recovery

Five plating agar media were evaluated for their ability to recover pure cultures of virulent strains of Yersinia enterocolitica serotypes O:3, O:8 and O:5,27. Cellobiose-arginine-lysine and bismuth sulfite agars were unproductive at 32°C but gave quantitative recovery with 48 h of incubation at 22°C. Adjustment of the pH of bismuth sulfite agar to 7.4 made the medium inhibitory. MacConkey, DHL and cefsulodin-irgasan-novobiocin agars gave quantitative recovery with 24 h of incubation at 32°C. Four preenrichment media incubated at four different temperatures, three selective enrichment media incubated at 22°C, and the five plating media were evaluated for their ability to recovery Y. enterocolitica from beef stew seeded with a background of ten other gram-negative bacteria. None of the plating media was superior for recovery; however, cefsulodin-irgasan-novobiocin agar showed the highest confirmation rate for presumptive colonies. Buffered-sorbitol-bile broth was inferior to richer media such as trypticase soy broth for preenrichment. Of the three selective enrichment media examined, only bile-oxalate-sorbose broth was found useful, especially for strains of serotype O:8 which could be recovered after 1 d of preenrichment and 3 d of selective enrichment at 22°C. Strains of serotypes O:8 and O:3 were recovered when two cells with 107 cells of ten other gram-negative bacteria were added to 10 g of beef stew following preenrichment in trypticase soy broth at 2°C for 7 d and selective enrichment in bile oxalate-sorbose broth at 22°C for 3 to 5 d. Strains of serotype O:5,27 were more difficult to recover even with longer enrichment times. These studies indicated that the most comprehensive enrichment system for recovery of Y. enterocolitica from foods is preenrichment in trypticase soy broth at 22°C for 1 d and 2 to 4°C for 4 to 7 d followed by selective enrichment in bile-oxalate-sorbose broth at 22°C for 3 to 5 d and isolation on cefsulodin-irgasan-novobiocin agar.

scholarly journals Revisiting the Gram-Negative Lipoprotein Paradigm

2015 ◽  
Vol 197 (10) ◽  
pp. 1705-1715 ◽  
Author(s):  
Eric D. LoVullo ◽  
Lori F. Wright ◽  
Vincent Isabella ◽  
Jason F. Huntley ◽  
Martin S. Pavelka
Keyword(s):  
Neisseria Gonorrhoeae ◽  
Francisella Tularensis ◽  
Live Vaccine Strain ◽  
Gram Negative Bacteria ◽  
The Novel ◽  
Gram Negative ◽  
Content Type ◽  
Sucrose Medium ◽  
Small Colony ◽  
Increased Susceptibility

ABSTRACTThe processing of lipoproteins (Lpps) in Gram-negative bacteria is generally considered an essential pathway. Mature lipoproteins in these bacteria are triacylated, with the final fatty acid addition performed by Lnt, an apolipoprotein N-acyltransferase. The mature lipoproteins are then sorted by the Lol system, with most Lpps inserted into the outer membrane (OM). We demonstrate here that thelntgene is not essential to the Gram-negative pathogenFrancisella tularensissubsp.tularensisstrain Schu or to the live vaccine strain LVS. An LVS Δlntmutant has a small-colony phenotype on sucrose medium and increased susceptibility to globomycin and rifampin. We provide data indicating that the OM lipoprotein Tul4A (LpnA) is diacylated but that it, and its paralog Tul4B (LpnB), still sort to the OM in the Δlntmutant. We present a model in which the Lol sorting pathway ofFrancisellahas a modified ABC transporter system that is capable of recognizing and sorting both triacylated and diacylated lipoproteins, and we show that this modified system is present in many other Gram-negative bacteria. We examined this model usingNeisseria gonorrhoeae, which has the same Lol architecture as that ofFrancisella, and found that thelntgene is not essential in this organism. This work suggests that Gram-negative bacteria fall into two groups, one in which full lipoprotein processing is essential and one in which the final acylation step is not essential, potentially due to the ability of the Lol sorting pathway in these bacteria to sort immature apolipoproteins to the OM.IMPORTANCEThis paper describes the novel finding that the final stage in lipoprotein processing (normally considered an essential process) is not required byFrancisella tularensisorNeisseria gonorrhoeae. The paper provides a potential reason for this and shows that it may be widespread in other Gram-negative bacteria.

scholarly journals A More Flexible Lipoprotein Sorting Pathway

2015 ◽  
Vol 197 (10) ◽  
pp. 1702-1704 ◽  
Author(s):  
Peter Chahales ◽  
David G. Thanassi
Keyword(s):  
Neisseria Gonorrhoeae ◽  
Francisella Tularensis ◽  
Gram Negative Bacteria ◽  
Acyl Transferase ◽  
Gram Negative ◽  
Content Type

Lipoprotein biogenesis in Gram-negative bacteria occurs by a conserved pathway, each step of which is considered essential. In contrast to this model, LoVullo and colleagues demonstrate that theN-acyl transferase Lnt is not required inFrancisella tularensisorNeisseria gonorrhoeae. This suggests the existence of a more flexible lipoprotein pathway, likely due to a modified Lol transporter complex, and raises the possibility that pathogens may regulate lipoprotein processing to modulate interactions with the host.

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