scholarly journals Bacteroides: the Good, the Bad, and the Nitty-Gritty

2007 ◽  
Vol 20 (4) ◽  
pp. 593-621 ◽  
Author(s):  
Hannah M. Wexler
Keyword(s):  
Resistance Mechanisms ◽  
Host Immune System ◽  
Toxic Substances ◽  
Human Gut ◽  
Bacteroides Species ◽  
Colonic Flora ◽  
Significant Pathology ◽  
Clinical Pathogens ◽  
Anaerobic Infections ◽  
Resistance Rates

SUMMARY Summary: Bacteroides species are significant clinical pathogens and are found in most anaerobic infections, with an associated mortality of more than 19%. The bacteria maintain a complex and generally beneficial relationship with the host when retained in the gut, but when they escape this environment they can cause significant pathology, including bacteremia and abscess formation in multiple body sites. Genomic and proteomic analyses have vastly added to our understanding of the manner in which Bacteroides species adapt to, and thrive in, the human gut. A few examples are (i) complex systems to sense and adapt to nutrient availability, (ii) multiple pump systems to expel toxic substances, and (iii) the ability to influence the host immune system so that it controls other (competing) pathogens. B. fragilis, which accounts for only 0.5% of the human colonic flora, is the most commonly isolated anaerobic pathogen due, in part, to its potent virulence factors. Species of the genus Bacteroides have the most antibiotic resistance mechanisms and the highest resistance rates of all anaerobic pathogens. Clinically, Bacteroides species have exhibited increasing resistance to many antibiotics, including cefoxitin, clindamycin, metronidazole, carbapenems, and fluoroquinolones (e.g., gatifloxacin, levofloxacin, and moxifloxacin).

scholarly journals Antimicrobial Resistance Profiles and Macrolide Resistance Mechanisms of Campylobacter coli Isolated from Pigs and Chickens

2021 ◽  
Vol 9 (5) ◽  
pp. 1077
Author(s):  
Ji-Hyun Choi ◽  
Dong Chan Moon ◽  
Abraham Fikru Mechesso ◽  
Hee Young Kang ◽  
Su-Jeong Kim ◽  
...  
Keyword(s):  
Nalidixic Acid ◽  
Ribosomal Proteins ◽  
Resistance Mechanisms ◽  
23S Rrna ◽  
Considerable Proportion ◽  
Rrna Gene ◽  
Campylobacter Coli ◽  
Erythromycin Resistance ◽  
Public Health Hazards ◽  
Resistance Rates

We identified 1218 Campylobacter coli isolates from fecal and carcass samples of pigs (n = 643) and chickens (n = 575) between 2010 and 2018. About 99% of the isolates were resistant to at least one antimicrobial agent. The isolates exhibited high resistance rates (>75%) to ciprofloxacin, nalidixic acid, and tetracycline. Azithromycin and erythromycin resistance rates were the highest in isolates from pigs (39.7% and 39.2%, respectively) compared to those of chickens (15.8% and 16.3%, respectively). Additionally, a low-to-moderate proportion of the isolates were resistant to florfenicol, gentamicin, clindamycin, and telithromycin. Multidrug resistance (MDR) was found in 83.1% of the isolates, and profiles of MDR usually included ciprofloxacin, nalidixic acid, and tetracycline. We found point mutation (A2075G) in domain V of the 23S rRNA gene in the majority of erythromycin-resistant isolates. Multilocus sequence typing of 137 erythromycin-resistant C. coli isolates revealed 37 previously reported sequence types (STs) and 8 novel STs. M192I, A103VI, and G74A substitutions were frequently noted in the ribosomal proteins L4 or L22. Further, we identified a considerable proportion (>90%) of erythromycin-resistant isolates carrying virulence factor genes: flaA, cadF, ceuE, and VirB. The prudent use of antimicrobials and regular microbiological investigation in food animals will be vital in limiting the public health hazards of C. coli in Korea.

scholarly journals Similarities Between Bacterial GAD and Human GAD65: Implications in Gut Mediated Autoimmune Type 1 Diabetes

2021 ◽  
Author(s):  
Monica Westley ◽  
Tiffany Richardson ◽  
Suhana Bedi ◽  
Baofeng Jia ◽  
Fiona S.L. Brinkman ◽  
...  
Keyword(s):  
Type 1 Diabetes ◽  
Beta Cells ◽  
Gut Microbiome ◽  
Pancreatic Beta Cells ◽  
Acid Decarboxylase ◽  
Host Immune System ◽  
Gamma Aminobutyric Acid ◽  
Human Gut ◽  
Autoimmune Attack

Abstract    A variety of islet autoantibodies (AAbs) can predict and possibly dictate eventual type 1 diabetes (T1D) diagnosis. Upwards of 75% of those with T1D are positive for AAbs against glutamic acid decarboxylase (GAD65), a producer of gamma-aminobutyric acid (GABA) in human pancreatic beta cells. Interestingly, bacterial populations within the human gut also express GAD65 and produce GABA. Evidence suggests that dysbiosis of the microbiome may correlate with T1D pathogenesis and physiology. Therefore, autoimmune linkages between the gut microbiome and islets susceptible to autoimmune attack need to be further elucidated. Utilizing silico analyses, we show here that 25 GAD sequences from different human gut bacterial sources show sequence and motif similarities to human beta cell GAD65. Our motif analyses determined that a majority of gut GAD sequences contain the pyroxical dependent decarboxylase domain of human GAD65 which is important for its enzymatic activity. Additionally, we showed overlap with known human GAD65 T-cell receptor epitopes which may implicate the immune destruction of beta cells. Thus, we propose a physiological hypothesis in which changes in the gut microbiome in those with T1D result in a release of bacterial GAD, thus causing miseducation of the host immune system. Due to the notable similarities, we found between humans and bacterial GAD, these deputized immune cells may then go on to target human beta cells leading to the development of T1D.

scholarly journals Impact of an Intervention to Control Imipenem-Resistant Acinetobacter baumannii and Its Resistance Mechanisms: An 8-Year Survey

2021 ◽  
Vol 11 ◽  
Author(s):  
Lida Chen ◽  
Pinghai Tan ◽  
Jianming Zeng ◽  
Xuegao Yu ◽  
Yimei Cai ◽  
...  
Keyword(s):  
Drug Resistance ◽  
Acinetobacter Baumannii ◽  
Bacterial Resistance ◽  
Efflux Pump ◽  
Resistance Mechanism ◽  
Resistance Mechanisms ◽  
Multi Drug Resistance ◽  
Minimal Inhibitory Concentrations ◽  
Resistance Rates ◽  
The Impact

BackgroundThis study aimed to examine the impact of an intervention carried out in 2011 to combat multi-drug resistance and outbreaks of imipenem-resistant Acinetobacter baumannii (IRAB), and to explore its resistance mechanism.MethodsA total of 2572 isolates of A. baumannii, including 1673 IRAB isolates, were collected between 2007 and 2014. An intervention was implemented to control A. baumannii resistance and outbreaks. Antimicrobial susceptibility was tested by calculating minimal inhibitory concentrations (MICs), and outbreaks were typed using pulsed-field gel electrophoresis (PFGE). Resistance mechanisms were explored by polymerase chain reaction (PCR) and whole genome sequencing (WGS).ResultsFollowing the intervention in 2011, the resistance rates of A. baumannii to almost all tested antibiotics decreased, from 85.3 to 72.6% for imipenem, 100 to 80.8% for ceftriaxone, and 45.0 to 6.9% for tigecycline. The intervention resulted in a decrease in the number (seven to five), duration (8–3 months), and departments (five to three) affected by outbreaks; no outbreaks occurred in 2011. After the intervention, only blaAMPC (76.47 to 100%) and blaTEM–1 (75.74 to 96.92%) increased (P < 0.0001); whereas blaGES–1 (32.35 to 3.07%), blaPER–1 (21.32 to 1.54%), blaOXA–58 (60.29 to 1.54%), carO (37.50 to 7.69%), and adeB (9.56 to 3.08%) decreased (P < 0.0001). Interestingly, the frequency of class B β-lactamase genes decreased from 91.18% (blaSPM–1) and 61.03% (blaIMP–1) to 0%, while that of class D blaOXA–23 increased to 96.92% (P < 0.0001). WGS showed that the major PFGE types causing outbreaks each year (type 01, 11, 18, 23, 26, and 31) carried the same resistance genes (blaKPC–1, blaADC–25, blaOXA–66, and adeABC), AdeR-S mutations (G186V and A136V), and a partially blocked porin channel CarO. Meanwhile, plasmids harboring blaOXA–23 were found after the intervention.ConclusionThe intervention was highly effective in reducing multi-drug resistance of A. baumannii and IRAB outbreaks in the long term. The resistance mechanisms of IRAB may involve genes encoding β-lactamases, efflux pump overexpression, outer membrane porin blockade, and plasmids; in particular, clonal spread of blaOXA–23 was the major cause of outbreaks. Similar interventions may also help reduce bacterial resistance rates and outbreaks in other hospitals.

scholarly journals Peering into the matrix: A look at biofilms and their inherent antibiotic resistance

SURG Journal ◽  
2013 ◽  
Vol 6 (2) ◽  
pp. 71-77
Author(s):  
Kevin J. Stinson
Keyword(s):  
Antibiotic Resistance ◽  
Phenotypic Variation ◽  
Extracellular Polymeric Substances ◽  
Resistance Mechanisms ◽  
Host Immune System ◽  
Bacterial Cells ◽  
Relative Significance ◽  
Adaptive Resistance ◽  
Persistent Infections ◽  
The Matrix

Biofilms are increasingly being regarded as the predominant form of bacterial growth in natural settings. These structures consist of bacterial cells immobilized at a surface and encased in a self-produced matrix of extracellular polymeric substances. In clinical settings, biofilms are the cause of persistent infections that are difficult to clear through the action of the host immune system. Biofilm-encased cells are also associated with increased levels of antibiotic resistance compared to their planktonic counterparts. The result is increased morbidity and mortality when biofilms are associated with disease. In this review, the focus of discussion will be the various mechanisms of antibiotic resistance common to biofilms and the role these mechanisms play in the pathogenesis of major clinically-relevant microorganisms. Antibiotic penetration, altered microenvironments, phenotypic variation, and adaptive resistance mechanisms are all key players in the development of antibiotic resistance in bacterial biofilms. Though the relative significance of each individual mechanism varies, when combined they confer extensive protection to the biofilm’s cellular populations. Keywords: biofilms; antibiotic resistance (mechanisms of); clinical applications; disease; antibiotic penetration; altered microenvironments; phenotypic variation; adaptive resistance; review

scholarly journals Molecular Epidemiology of Carbapenem-Resistant Klebsiella pneumoniae Infections in Southwest China

2020 ◽  
Author(s):  
Xiaopin Hu ◽  
Guohang Yuan ◽  
Yaoyao Wu ◽  
Weijia Liu ◽  
Xiangyan Zhang ◽  
...  
Keyword(s):  
Klebsiella Pneumoniae ◽  
Southwest China ◽  
Antibiotic Use ◽  
Resistance Mechanisms ◽  
Control Measures ◽  
Invasive Procedures ◽  
Carbapenem Resistant ◽  
Tertiary Hospitals ◽  
Resistance Rates ◽  
Epidemiological Characteristics

Abstract Background: We determined epidemiological characteristics and resistance mechanisms of carbapenem-resistant Klebsiella pneumoniae (CRKP) strains found in Southwest China and assessed disease burden to provide evidence-based strategies for control and treatment of CRKP infection. Methods: A total of 159 strains of CRKP were isolated from sputa, blood, urine, ascites and wound secretions from three tertiary hospitals in Southwest China between August 1st, 2018 and December 31st, 2019. The sensitivity of each strain to 12 antibiotic agents was determined by micro-broth dilution. Identification of carbapenemase genes and multi-locus sequence typing (MLST) were performed using polymerase chain reaction (PCR). The disease burdens of patients with CRKP were assessed based on invasive procedures, antibiotic use, laboratory tests and clinical outcomes. Results: Of 159 CRKP strains analyzed, 50.9% were isolated from sputum samples. The percentage of patients who underwent invasive procedures before positive cultures for CRKP were detected was 96.3%. The mortality of blood infection was highest (66.6%) among patients with CRKP infection. All strains were insensitive to carbapenems. The resistance rates to levofloxacin and amikacin were 85.5% and 81.8%, respectively. All CRKP strains produced carbapenemases, with a majority of isolates (81.1%) producing KPC-2. The MICs of strains harbouring both KPC-2 and NDM-1 were higher than those of strains with only KPC-2 or NDM-1. ST11 is the most popular clonotype found in Southwest China. Conclusions: CRKP strains in Southwest China are characterized by strong drug resistance and associated with poor clinical prognoses. It is therefore urgent to both strengthen control measures and improve prevention awareness.

scholarly journals Epidemiology and antimicrobial resistance of B. fragilis group organisms isolated from clinical specimen and human intestinal microbiota

1996 ◽  
Vol 38 (5) ◽  
pp. 329-336 ◽  
Author(s):  
Cibele Barreto Mano de Carvalho ◽  
José Luciano Bezerra Moreira ◽  
Maria Candida S. Ferreira
Keyword(s):  
Soft Tissue ◽  
Intestinal Microbiota ◽  
Antimicrobial Susceptibility ◽  
Clinical Specimen ◽  
Chronic Otitis Media ◽  
University Hospitals ◽  
Anaerobic Infections ◽  
Resistance Rates ◽  
Susceptibility Profiles ◽  
Susceptibility Patterns

Epidemiological aspects and the antimicrobial susceptibility profile of the Bacteroides fragilis group isolated from clinical and human intestinal specimens were examined in this study. B. fragilis group strains were isolated from 46 (37%) of 124 clinical specimens and the source of the samples was: Blood culture (3), intraabdominal infection (27), brain abscess (2), soft tissue infection (17), respiratory sinus (3), pleural aspirate (9), breast abscess (3), surgical infected wound (22), pelvic inflammatory disease (22), chronic otitis media (9) and miscellaneous (7). Intraabdominal and soft tissue infections were responsible for more than half of the clinical isolates. Susceptibility to penicillin, cefoxitin, tetracycline, metronidazole, chloramphenicol and clindamycin was examined. All isolates were susceptible to metronidazole and chloramphenicol. For clindamycin and cefoxitin the resistance rates observed were 21.7% and 10.9% respectively. Susceptibility profiles varied among the different species tested. A total of 37 species of B. fragilis group isolated from intestinal microbiota of individuals who had no antimicrobial therapy for at least 1 month before the sampling was also examined. All strains were also susceptible to chloramphenicol and motronidazole and the resistance rates to clindamycin and cefoxitin were 19.4% and 5.4% respectively. A few institutions, in Brazil, have monitored the antimicrobial susceptibility of B. fragilis group strains isolated from anaerobic infections. The resistance rates to cefoxitin and clindamycin and the variation in susceptibility patterns among the species isolated in this study emphasize the need for monitoring of susceptibility patterns of B. fragilis group organisms isolated, especially at our University Hospitals.

scholarly journals 1049. Outcome and Impact of Empirical Antimicrobial Treatment in Bacteraemia With Bacteroides Species; A Retrospective Cohort Study in a Region of Southern Sweden

2018 ◽  
Vol 5 (suppl_1) ◽  
pp. S313-S313
Author(s):  
Johan Tham ◽  
Karolina Kalin ◽  
Fredrik Resman ◽  
Karin Holm
Keyword(s):  
Cohort Study ◽  
Antibiotic Treatment ◽  
Retrospective Cohort Study ◽  
Retrospective Cohort ◽  
Early Recognition ◽  
Antimicrobial Treatment ◽  
Bacteroides Species ◽  
Appropriate Treatment ◽  
Severe Infections ◽  
Anaerobic Infections

Abstract Background Anaerobic infections are an important cause of bacteremia and severe Infections. Due to increasing extended spectrum β-lactamase resistance (ESBL), the treatment recommendations for anaerobic infections in Sweden have changed during the past ten years. The effects of anaerobe resistance and outcome for patients with anaerobe infections is unclear. Methods A retrospective cohort study was conducted in patients with bacteraemia due to Bacteroides species in the Region of Skåne between 2011 and 2015. Data on patients were reviewed from medical and microbiological records and we determined the factors associated with 28-day mortality using a multivariate regression model. Results Data on 454 patients were reviewed from medical and microbiological records and 389 (median age, 76 years; male, 54%) met the inclusion criteria. The 28-day all-cause mortality rate was 19% (72/389). Inadequate empirical antibiotic therapy occurred among 182 (47%) patients, and we found a trend toward that inadequate antibiotic treatment increased the 28-day mortality (P = 0.055). The frequency of bacteraemia with Bacteroides increased during the period of time and Bacteroides fragilis was the most common bacteria, 55% (212/389). The resistance against piperacillin/tazobactam was higher than in many other studies and among the different Bacteroides isolates that were resistant to piperacillin/tazobactam, Bacteroides thetaiotamicron was the most prevalent with 60% (50/83) being resistant. Piperacillin/tazobactam was the frequently used antimicrobial agent against Bacteroides infections and the utilization was increasing. We did not find any resistance among the Bacteroides isolates against metronidazole and only three isolates were resistant against carbapenems. Conclusion Anaerobe resistance is an increasing issue and especially against the most common antibiotic treatment, piperacillin/tazobactam. Early recognition and appropriate treatment is important to avoid proliferation of these increasing bacteria since inadequate treatment increased the mortality. Disclosures All authors: No reported disclosures.

scholarly journals Staphylococcal Osteomyelitis: Disease Progression, Treatment Challenges, and Future Directions

2018 ◽  
Vol 31 (2) ◽  
Author(s):  
Nicola Kavanagh ◽  
Emily J. Ryan ◽  
Amro Widaa ◽  
Gillian Sexton ◽  
Jerome Fennell ◽  
...  
Keyword(s):  
Staphylococcus Epidermidis ◽  
Clinical Presentation ◽  
Surgical Intervention ◽  
Bone Destruction ◽  
Resistance Mechanisms ◽  
Host Immune System ◽  
Future Directions ◽  
Content Type ◽  
Persistent Infections ◽  
Global Concern

SUMMARYOsteomyelitis is an inflammatory bone disease that is caused by an infecting microorganism and leads to progressive bone destruction and loss. The most common causative species are the usually commensal staphylococci, withStaphylococcus aureusandStaphylococcus epidermidisresponsible for the majority of cases. Staphylococcal infections are becoming an increasing global concern, partially due to the resistance mechanisms developed by staphylococci to evade the host immune system and antibiotic treatment. In addition to the ability of staphylococci to withstand treatment, surgical intervention in an effort to remove necrotic and infected bone further exacerbates patient impairment. Despite the advances in current health care, osteomyelitis is now a major clinical challenge, with recurrent and persistent infections occurring in approximately 40% of patients. This review aims to provide information about staphylococcus-induced bone infection, covering the clinical presentation and diagnosis of osteomyelitis, pathophysiology and complications of osteomyelitis, and future avenues that are being explored to treat osteomyelitis.

scholarly journals Molecular Epidemiology of Staphylococcus epidermidis Clinical Isolates from U.S. Hospitals

2012 ◽  
Vol 56 (9) ◽  
pp. 4656-4661 ◽  
Author(s):  
Rodrigo E. Mendes ◽  
Lalitagauri M. Deshpande ◽  
Andrew J. Costello ◽  
David J. Farrell
Keyword(s):  
Staphylococcus Epidermidis ◽  
Resistance Mechanisms ◽  
23S Rrna ◽  
Content Type ◽  
Linezolid Resistance ◽  
Clonal Distribution ◽  
Resistant Strains ◽  
Resistance Rates ◽  
Susceptibility Profiles ◽  
Sequence Types

ABSTRACTThe epidemiology ofStaphylococcus epidermidisin U.S. hospitals remains limited. This study aimed to address the genetic backgrounds of linezolid-susceptible and -resistantS. epidermidisstrains (isolated in 2010), includingcfr-carrying strains. In addition, the antimicrobial susceptibility profiles and linezolid resistance mechanisms among clonal lineages were assessed. A total of 71S. epidermidisisolates were selected, and linezolid-resistant strains were screened forcfrand mutations in 23S rRNA, L3, and L4. All isolates were subjected to multilocus sequence typing (MLST), and the results were analyzed by eBURST. Overall, 27 sequence types (STs) were detected, and ST5 (21.1%) and ST2 (16.9%) predominated. The majority (62/71; 87.3%) of STs belonged to clonal complex 2 (CC2), which was mostly comprised of subclusters CC2-II (41/62; 66.1%) and CC2-I (21/62; 33.9%). Other STs were grouped within CC23 or CC32 or were singletons. CC2-I strains were more likely to display a methicillin (95.2% versus 33.3 to 70.7%), a linezolid (47.6% versus 0.0 to 7.3%), or a multidrug (81.0% versus 33.3 to 36.6%) resistance phenotype. Among linezolid-resistant isolates,cfrwas noted only within CC2 strains, and it was detected equally in the CC2-I (3/10; 30.0%) and CC2-II (1/3; 33.3%) subclusters. 23S rRNA mutations (G2576 [seven strains] and C2534 [one strain]) were observed only among CC2-I (8/10; 80.0%) isolates. Strains showing a G2576 alteration also had M156 (7/7; 100.0%) and/or H146 (6/7; 85.7%) L3 modifications. This study provides an overview of theS. epidermidisclonal distribution and reports higher resistance rates among CC2-I strains. The results show thatcfrmay be acquired and expressed by both CC2 main subclusters, while 23S rRNA mutations appeared more often within CC2-I strains. Interestingly, these 23S rRNA mutants also had L3 alterations, which may act synergistically or in a compensatory manner to minimize the fitness cost while providing survival advantages under selective pressure.

scholarly journals Fusidic Acid Resistance Rates and Prevalence of Resistance Mechanisms among Staphylococcus spp. Isolated in North America and Australia, 2007-2008

2010 ◽  
Vol 54 (9) ◽  
pp. 3614-3617 ◽  
Author(s):  
Mariana Castanheira ◽  
Amy A. Watters ◽  
Jan M. Bell ◽  
John D. Turnidge ◽  
Ronald N. Jones
Keyword(s):  
United States ◽  
Resistance Genes ◽  
Fusidic Acid ◽  
Dominant Role ◽  
Acquired Resistance ◽  
Resistance Mechanism ◽  
Acid Resistance ◽  
The United States ◽  
Resistance Mechanisms ◽  
Resistance Rates

ABSTRACT Among 4,167 Staphylococcus aureus and 790 coagulase-negative Staphylococcus (CoNS; not S. saprophyticus) isolates collected consecutively from North American and Australian hospitals, only 87 (1.7% overall) isolates displayed a fusidic acid (FA; also known as CEM-102) MIC of ≥2 μg/ml (FA resistance). These strains were further evaluated with a multiplex PCR to amplify the acquired resistance genes fusB, fusC, and fusD. Mutations in fusA and fusE were evaluated in all isolates showing an absence of acquired resistance genes and/or showing FA MIC values of ≥64 μg/ml. S. aureus resistance rates were very low in the United States (0.3%) and were higher in Canada and Australia (7.0% for both countries). Among CoNS isolates, FA resistance rates were significantly more elevated than that for S. aureus (7.2 to 20.0%; the highest rates were in Canada). All 52 (41 CoNS) FA-resistant isolates from the United States showed FA MIC results of ≤64 μg/ml, and 7 of 11 S. aureus isolates carried fusC. CoNS strains from the United States carried fusB or fusC. In Canada, fusB and fusC occurrences were similar among S. aureus and CoNS isolates, and modestly elevated FA MIC values were observed (all MIC results were ≤32 μg/ml). Isolates from Australia showed MIC values ranging from 2 to 32 μg/ml, and S. aureus isolates were predominantly fusC positive. fusA mutations were detected in only three S. aureus isolates, conferring FA MIC values of 2 to 8 μg/ml. Target mutations have been considered the primary FA resistance mechanism among Staphylococcus spp.; however, acquired resistance genes appear to have a dominant role in resistance against this older antimicrobial agent. In summary, this study shows that acquired genes are highly prevalent among FA-resistant strains (>90%) in three nations with distinct or absence (United States) of fusidic acid clinical use.

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