scholarly journals Gram-negative bacilli bacteremia: a 7 year retrospective study in a referral Brazilian tertiary-care teaching hospital

2020 ◽  
Author(s):  
Maria Clara Bisaio Quillici ◽  
Daiane Silva Resende ◽  
Iara Rossi Gonçalves ◽  
Sabrina Royer ◽  
Sebastiana Silva Sabino ◽  
...  
Keyword(s):  
Septic Shock ◽  
Antibiotic Therapy ◽  
Bloodstream Infection ◽  
Teaching Hospital ◽  
Type Species ◽  
Bloodstream Infections ◽  
Gram Negative ◽  
Content Type ◽  
Link Type ◽  
Initial Antibiotic Therapy

Introduction. Bloodstream infection is one of the most frequent and challenging hospital-acquired infections and it is associated with high morbidity, mortality and additional use of healthcare resources. Hypothesis/Gap Statement: Bloodstream infections have consequences for the patient, such as the evolution to mortality and inappropriate empirical antibiotic prescription, especially when caused by multidrug-resistant Gram-negative bacilli. Objective. To assess the impact of bloodstream infection and the status of multidrug resistance (MDR) in the evolution of patients who received inappropriate initial antibiotic therapy. Methods. A retrospective surveillance was conducted on nosocomial bloodstream infections caused by Gram-negative bacilli (GNB) from January 2012 to December 2018 in an adult intensive care unit of a Brazilian tertiary teaching hospital. Results. We identified 270 patients with GNB nosocomial bacteremia. Non-survivors were older (with an average age of 58.8 years vs 46.9 years, P=<0.0001), presented more severe illnesses, were immunosuppressed (73.7 vs 37.6%, P=<0.0001), were more likely to have septic shock (55.8 vs 22.4%, P=<0.0001) and had an increased usage of mechanical ventilators (98.6 vs 89.6%, P=0.0013) than survivors. In a logistic regression model, inappropriate empirical antibiotic therapy was not an independent predictor of mortality, different from mechanical ventilator (P=<0.0001; OR=28.0; 95% CI=6.3–123.6), septic shock (P=0.0051; OR=2.5; 95% CI=1.3–4.9) and immunosuppression (P=0.0066; OR=2.6; 95% CI=1.3–5.2). In contrast, in a separate model, MDR was strongly associated with the prescription of inappropriate initial antibiotic therapy (P=0.0030; OR=5.3; 95% CI=1.7–16.1). The main isolated pathogens were Acinetobacter baumannii (23.6 %) and Klebsiella pneumoniae (18.7 %). The frequency of MDR organisms was high (63.7 %), especially among non-fermenting bacilli (60.9 %), highlighting A. baumannii (81.6 %) and Pseudomonas aeruginosa (41.8 %). Conclusion. Illness severity (septic shock and immunosuppression) and mechanical ventilation were identified as predictors of mortality. Additionally, MDR was a major determinant of inappropriate antibiotic empirical therapy, but not associated with mortality, and both characteristics were not statistically associated with death.

scholarly journals Rapid Sepsityper in clinical routine: 2 years’ successful experience

2020 ◽  
Vol 69 (12) ◽  
pp. 1398-1404
Author(s):  
Miriam Cordovana ◽  
Anna Zignoli ◽  
Simone Ambretti
Keyword(s):  
Sample Preparation ◽  
Causative Agent ◽  
Type Species ◽  
Susceptibility Testing ◽  
Preparation Method ◽  
Bloodstream Infections ◽  
Routine Practice ◽  
Sample Preparation Method ◽  
Content Type ◽  
Link Type

Introduction. Rapid identification of the causative agent of sepsis is crucial for patient outcomes. Aim. The Sepsityper sample preparation method enables direct microbial identification of positive blood culture samples via matrix-assisted laser desorption ionization/time-of-flight mass spectrometry (MALDI-TOF MS). Hypothesis/Gap statement. The implementation of the Sepsityper method in the routine practice could represent a fundamental tool to achieve a prompt identification of the causative agent of bloodstream infections, and therefore accelerate the adoption of the proper antibiotic treatment. Methodology. In this study, the novel rapid workflow of the MALDI Biotypr Sepsityper kit (Bruker Daltonik GmbH, Germany) was evaluated using routine samples from a 2-year period (n=6918), and dedicated optimized protocols for the microbial groups that were more difficult to identify were developed. Moreover, the use of the residual bacterial pellet to perform susceptibility testing using different methods (commercial broth microdilution, disc diffusion, gradient diffusion) was investigated. Results. The rapid Sepsityper protocol allowed the identification of 5470/6338 (86.3 %) monomicrobial samples at species level, with very good performance for all of the clinically most significant pathogens (2510/2592 enterobacteria, 631/669 Staphylococcus aureus and 223/246 enterococci were identified). Streptococcus pneumoniae , Bacteroides fragilis and yeasts were the most troublesome to identify, but the application of specific optimized protocols significantly improved their rate of identification (from 14.7–71.5 %, 47.8–89.7 % and 37.1–89.5 %, respectively). Specificity was 100 % (no identification was made for the false-positive samples). Further, the residual pellet proved to be suitable to investigate susceptibility to antimicrobials, enabling us to simplify the workflow and shorten the time to report. Conclusion. The Rapid Sepsityper workflow proved to be a reliable sample preparation method for identification and susceptibility testing directly from positive blood cultures, providing novel approaches for accelerated diagnostics of bloodstream infections.

scholarly journals In vitro synergy of 5-nitrofurans, vancomycin and sodium deoxycholate against Gram-negative pathogens

2021 ◽  
Author(s):  
Catrina Olivera ◽  
Vuong Van Hung Le ◽  
Catherine Davenport ◽  
Jasna Rakonjac
Keyword(s):  
Growth Inhibition ◽  
Type Species ◽  
Sodium Deoxycholate ◽  
Gram Positive ◽  
Bacterial Killing ◽  
Gram Negative ◽  
Content Type ◽  
Link Type ◽  
Time Kill

Introduction. There is an urgent need for effective therapies against bacterial infections, especially those caused by antibiotic-resistant Gram-negative pathogens. Hypothesis. Synergistic combinations of existing antimicrobials show promise due to their enhanced efficacies and reduced dosages which can mitigate adverse effects, and therefore can be used as potential antibacterial therapy. Aim. In this study, we sought to characterize the in vitro interaction of 5-nitrofurans, vancomycin and sodium deoxycholate (NVD) against pathogenic bacteria. Methodology. The synergy of the NVD combination was investigated in terms of growth inhibition and bacterial killing using checkerboard and time-kill assays, respectively. Results. Using a three-dimensional checkerboard assay, we showed that 5-nitrofurans, sodium deoxycholate and vancomycin interact synergistically in the growth inhibition of 15 out of 20 Gram-negative strains tested, including clinically significant pathogens such as carbapenemase-producing Escherichia coli , Klebsiella pneumoniae and Acinetobacter baumannii , and interact indifferently against the Gram-positive strains tested. The time-kill assay further confirmed that the triple combination was bactericidal in a synergistic manner. Conclusion. This study demonstrates the synergistic effect of 5-nitrofurans, sodium deoxycholate and vancomycin against Gram-negative pathogens and highlights the potential of the combination as a treatment for Gram-negative and Gram-positive infections.

scholarly journals Genomic investigation of a suspected Klebsiella pneumoniae outbreak in a neonatal care unit in sub-Saharan Africa

2021 ◽  
Vol 7 (11) ◽  
Author(s):  
Jennifer Cornick ◽  
Patrick Musicha ◽  
Chikondi Peno ◽  
Ezgi Seager ◽  
Pui-Ying Iroh Tam ◽  
...  
Keyword(s):  
Klebsiella Pneumoniae ◽  
Resistance Genes ◽  
Type Species ◽  
Bloodstream Infections ◽  
Sub Saharan Africa ◽  
Content Type ◽  
Link Type ◽  
Sub Saharan ◽  
Neonatal Care Unit ◽  
Suspected Outbreak

A special-care neonatal unit from a large public hospital in Malawi was noted as having more frequent, difficult-to-treat infections, and a suspected outbreak of multi-drug-resistant Klebsiella pneumoniae was investigated using genomic characterisation. All K. pneumoniae bloodstream infections (BSIs) from patients in the neonatal ward (n=62), and a subset of K. pneumoniae BSI isolates (n=38) from other paediatric wards in the hospital, collected over a 4 year period were studied. After whole genome sequencing, the strain sequence types (STs), plasmid types, virulence and resistance genes were identified. One ST340 clone, part of clonal complex 258 (CC258) and an ST that drives hospital outbreaks worldwide, harbouring numerous resistance genes and plasmids, was implicated as the likely cause of the outbreak. This study contributes molecular information necessary for tracking and characterizing this important hospital pathogen in sub-Saharan Africa.

scholarly journals Infective endocarditis caused by Cardiobacterium valvarum

2019 ◽  
Vol 1 (8) ◽  
Author(s):  
Yohei Washio ◽  
Shun-ichiro Sakamoto ◽  
Ryoichi Saito ◽  
Takahito Nei ◽  
Masayo Morishima ◽  
...  
Keyword(s):  
Infective Endocarditis ◽  
Ribosomal Rna ◽  
Transthoracic Echocardiography ◽  
Type Species ◽  
Blood Cultures ◽  
Gram Negative ◽  
Content Type ◽  
Link Type ◽  
Conventional Methods ◽  
Positive Results

We report a case with infective endocarditis (IE) due to Cardiobacterium valvarum . The patient was a 57-year-old male, who was referred to our hospital based on suspected IE detected by transthoracic echocardiography at a neighbourhood clinic. Three sets of blood cultures obtained on admission yielded positive results, and revealed rather slender and linear Gram-negative bacilli with a rosette formation that dyed minimally, with a pale white appearance. Although no isolates were identified by conventional methods, C. valvarum was ultimately identified by 16 S ribosomal RNA genotyping. HACEK group strains are difficult to identify by conventional methods. Therefore, if Gram-negative bacilli are isolated from IE patients, 16 S ribosomal RNA genotyping will be necessary. Furthermore, IE due to C. valvarum is very rare. We thus discuss our case in comparison with previous reports.

scholarly journals Loss of the virulence plasmid by Shigella sonnei promotes its interactions with CD207 and CD209 receptors

2021 ◽  
Vol 70 (3) ◽  
Author(s):  
Bi-cong Wu ◽  
Njiri A. Olivia ◽  
John Mambwe Tembo ◽  
Ying-xia He ◽  
Ying-miao Zhang ◽  
...  
Keyword(s):  
Type Species ◽  
Shigella Sonnei ◽  
Virulence Plasmid ◽  
Gram Negative Bacteria ◽  
Lectin Receptors ◽  
Gram Negative ◽  
Content Type ◽  
Link Type ◽  
O Antigen ◽  
Rough Strain

Introduction. Shigella sonnei, the cause of bacillary dysentery, belongs to Gram-negative enteropathogenic bacteria. S. sonnei contains a 210 kb virulence plasmid that encodes an O-antigen gene cluster of LPSs. However, this virulence plasmid is frequently lost during replication. It is well-documented that after losing the O-antigen and becoming rough strains, the Gram-negative bacteria may express an LPS core on its surface. Previous studies have suggested that by using the LPS core, Gram-negative bacteria can interact with several C-type lectin receptors that are expressed on antigen-presenting cells (APCs). Hypothesis/Gap Statement. S. sonnei by losing the virulence plasmid may hijack APCs via the interactions of LPS-CD209/CD207. Aim. This study aimed to investigate if the S. sonnei rough strain, by losing the virulence plasmid, interacted with APCs that express C-type lectins of human CD207, human CD209a and mouse CD209b. Methodology. SDS-PAGE silver staining was used to examine the O-antigen expression of S. sonnei WT and its rough strain. Invasion assays and inhibition assays were used to examine the ability of S. sonnei WT and its rough strain to invade APCs and investigate whether CD209 and CD207 are receptors for phagocytosis of rough S. sonnei . Animal assays were used to observe the dissemination of S. sonnei . Results. S. sonnei did not express O-antigens after losing the virulence plasmid. The S. sonnei rough strain invades with APCs, including human dendritic cells (DCs) and mouse macrophages. CD209 and CD207 are receptors for phagocytosis of rough S. sonnei . Expression of the O-antigen reduces the ability of the S. sonnei rough strain to be disseminated to mesenteric lymph nodes and spleens. Conclusion. This work demonstrated that S. sonnei rough strains – by losing the virulence plasmid – invaded APCs through interactions with CD209 and CD207 receptors.

Arenimonas daechungensis sp. nov., isolated from the sediment of a eutrophic reservoir

2013 ◽  
Vol 63 (Pt_2) ◽  
pp. 484-489 ◽  
Author(s):  
Hangsak Huy ◽  
Long Jin ◽  
Young-Ki Lee ◽  
Keun Chul Lee ◽  
Jung-Sook Lee ◽  
...  
Keyword(s):  
Dna Hybridization ◽  
Type Strain ◽  
Type Species ◽  
Novel Species ◽  
Genetic Data ◽  
Rrna Gene ◽  
16S Rrna Gene Sequences ◽  
Gram Negative ◽  
Content Type ◽  
Link Type

A Gram-negative, non-motile, non-spore-forming and rod-shaped bacterial strain, CH15-1T, was isolated from a sediment sample taken from Daechung Reservoir, South Korea, during the late-blooming period of cyanobacteria. Strain CH15-1T grew optimally at pH 7.0 and 30 °C. A phylogenetic analysis based on 16S rRNA gene sequences confirmed that strain CH15-1T belongs to the genus Arenimonas with the similarity range from 92.6–97.4 % and is closely related to Arenimonas oryziterrae YC6267T (97.4 %), Arenimonas composti TR7-09T (95.4 %), Arenimonas metalli CF5-1T (94.7 %), Arenimonas malthae CC-JY-1T (94.6 %) and Arenimonas donghaensis HO3-R19T (92.6 %). However, the DNA–DNA hybridization between strain CH15-1T and the closest strain, Arenimonas oryziterrae YC6267T, was 8.9–12.9 %. The DNA G+C content was 63.9 mol% compared to A. oryziterrae YC626T, 65.8 mol%. Strain CH15-1T included Q-8 as the major ubiquinone and phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol and phosphatidylmonomethylethanolamine as the major polar lipids. The major fatty acids (>5 %) were iso-C15 : 0, iso-C16 : 0, iso-C14 : 0, iso-C11 : 0 3-OH, iso-C17 : 0 and summed feature 9 (iso-C17 : 1ω9c and/or C16 : 0 10-methyl). On the basis of phylogenetic, phenotypic and genetic data, strain CH15-1T was classified in the genus Arenimonas as a member of a novel species, for which the name Arenimonas daechungensis sp. nov. is proposed. The type strain is CH15-1T ( = KCTC 23553T = DSM 24763T).

scholarly journals Veillonella nakazawae sp. nov., an anaerobic Gram-negative coccus isolated from the oral cavity of Japanese children

2020 ◽  
Author(s):  
Izumi Mashima ◽  
Citra F. Theodorea ◽  
Ariadna A. Djais ◽  
Tadao Kunihiro ◽  
Yoshiaki Kawamura ◽  
...  
Keyword(s):  
16S Rrna ◽  
Oral Cavity ◽  
Related Species ◽  
Type Strain ◽  
Type Species ◽  
Japanese Children ◽  
Closely Related Species ◽  
Gram Negative ◽  
Content Type ◽  
Link Type

Two strains of previously unknown Gram-negative cocci, T1-7T and S6-16, were isolated from the oral cavity of healthy Japanese children. The two strains showed atypical phenotypic characteristics of members of the genus Veillonella , including catalase production. Sequencing of their 16S rRNA genes confirmed that they belong to genus Veillonella . Under anaerobic conditions, the two strains produced acetic acid and propionic acid as metabolic end-products in a trypticase–yeast extract–haemin medium containing 1 % (w/v) glucose, 1 % (w/v) fructose and 1 % (v/v) sodium lactate. Comparative analysis of the 16S rRNA, dnaK, rpoB and gltA gene sequences revealed that the two strains are phylogenetically homogeneous and comprise a distinct, novel lineage within the genus Veillonella . The sequences from the two strains shared the highest similarity, at 99.9, 95.8, 96.9 and 96.7 %, using the partial 16S rRNA, dnaK, rpoB and gltA gene sequences, respectively, with the type strains of the two most closely related species, Veillonella dispar ATCC 17748T and Veillonella infantium JCM 31738T. Furthermore, strain T1-7T shared the highest average nucleotide identity (ANI) value (94.06 %) with type strain of the most closely related species, V. infantium . At the same time, strain T1-7T showed the highest digital DNA–DNA hybridization (dDDH) value (55.5 %) with the type strain of V. infantium . The two strains reported in this study were distinguished from the previously reported species from the genus Veillonella based on catalase production, partial dnaK, rpoB and gltA sequences, average ANI and dDDH values. Based on these observations, the two strains represent a novel species, for which the name Veillonella nakazawae sp. nov. is proposed. The type strain is T1-7T (JCM 33966T=CCUG 74597T).

scholarly journals Does concomitant bacteraemia hide the fungi in blood cultures? An in vitro study

2020 ◽  
Vol 69 (7) ◽  
pp. 944-948
Author(s):  
Yasemin Oz ◽  
Sukran Onder ◽  
Ekin Alpaslan ◽  
Gul Durmaz
Keyword(s):  
Blood Culture ◽  
Bloodstream Infection ◽  
Microscopic Examination ◽  
Type Species ◽  
Blood Cultures ◽  
Specific Patient ◽  
Content Type ◽  
Link Type ◽  
Direct Microscopic Examination ◽  
Positive Direct

Introduction. Polymicrobial infections including yeasts and bacteria are not rare and patients with polymicrobial bloodstream infection have higher early and overall case fatality rates. The diagnosis of invasive fungal and bacterial infections is mainly based on blood culture. Aim. The aim was to reveal the effect of concomitant bacteraemia on the detection of fungi from blood cultures in the presence of polymicrobial bloodstream infections involving Candida and non-Candida fungi and to show the superiority of blood culture bottles including selective fungal media in such situations. Methodology. Twenty-four polymicrobial bloodstream infection models – involving one fungus and one bacterium – were constituted by using clinical blood culture isolates ( Escherichia coli , Staphylococcus aureus , Pseudomonas aeruginosa , Candida albicans, Candida glabrata, Fusarium solani and Trichosporon asahii). The Plus Aerobic/F (PAF) and Mycosis IC/F (MICF) culture bottles were used with the BACTEC 9240 device. After a bottle signalled positive, direct microscopic examination and subcultures on agar plates were performed. Results. All of fungi that were inoculated alone and in combination were detected by both direct microscopic examination and subcultures on agar plates from MICF bottles, whereas direct microscopic examination only revealed the bacterial agents from PAF bottles including combinations. Furthermore, fungal growth was hidden by bacterial growth on blood agar subcultures from PAF bottles including combinations of F. solani, C. glabrata or T. asahii with bacteria. Conclusion. Blood culture bottles including selective fungal media that can allow selective growth of fungi and earlier detection of some species should be preferred in addition to non-selective blood culture bottles, especially in specific patient populations. Further, the use of selective agar plates such as inhibitory mould agar may contribute to the solution of this problem in clinical laboratories.

scholarly journals Co-infection in critically ill patients with COVID-19: an observational cohort study from England

2021 ◽  
Vol 70 (4) ◽  
Author(s):  
Vadsala Baskaran ◽  
Hannah Lawrence ◽  
Louise E. Lansbury ◽  
Karmel Webb ◽  
Shahideh Safavi ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Cohort Study ◽  
Streptococcus Pneumoniae ◽  
Critically Ill ◽  
Type Species ◽  
Severe Illness ◽  
Gram Negative ◽  
Content Type ◽  
Link Type ◽  
Icu Stay

Introduction. During previous viral pandemics, reported co-infection rates and implicated pathogens have varied. In the 1918 influenza pandemic, a large proportion of severe illness and death was complicated by bacterial co-infection, predominantly Streptococcus pneumoniae and Staphylococcus aureus . Gap statement. A better understanding of the incidence of co-infection in patients with COVID-19 infection and the pathogens involved is necessary for effective antimicrobial stewardship. Aim. To describe the incidence and nature of co-infection in critically ill adults with COVID-19 infection in England. Methodology. A retrospective cohort study of adults with COVID-19 admitted to seven intensive care units (ICUs) in England up to 18 May 2020, was performed. Patients with completed ICU stays were included. The proportion and type of organisms were determined at <48 and >48 h following hospital admission, corresponding to community and hospital-acquired co-infections. Results. Of 254 patients studied (median age 59 years (IQR 49–69); 64.6 % male), 139 clinically significant organisms were identified from 83 (32.7 %) patients. Bacterial co-infections/ co-colonisation were identified within 48 h of admission in 14 (5.5 %) patients; the commonest pathogens were Staphylococcus aureus (four patients) and Streptococcus pneumoniae (two patients). The proportion of pathogens detected increased with duration of ICU stay, consisting largely of Gram-negative bacteria, particularly Klebsiella pneumoniae and Escherichia coli . The co-infection/ co-colonisation rate >48 h after admission was 27/1000 person-days (95 % CI 21.3–34.1). Patients with co-infections/ co-colonisation were more likely to die in ICU (crude OR 1.78,95 % CI 1.03–3.08, P=0.04) compared to those without co-infections/ co-colonisation. Conclusion. We found limited evidence for community-acquired bacterial co-infection in hospitalised adults with COVID-19, but a high rate of Gram-negative infection acquired during ICU stay.

Evaluation of the rapid ResaPolymyxin Acinetobacter/Pseudomonas NP test for rapid colistin resistance detection in lactose non-fermenting Gram-negative bacteria

2021 ◽  
Vol 70 (6) ◽  
Author(s):  
Hyunsul Jung ◽  
Johann D. D. Pitout ◽  
Barend C. Mitton ◽  
Kathy-Anne Strydom ◽  
Chanel Kingsburgh ◽  
...  
Keyword(s):  
Type Species ◽  
Susceptibility Testing ◽  
Multidrug Resistant ◽  
Gram Negative Bacteria ◽  
Major Error ◽  
Colistin Resistance ◽  
Gram Negative ◽  
Content Type ◽  
Link Type ◽  
Extensively Drug Resistant

Introduction. Colistin is one of the last-resort antibiotics for treating multidrug-resistant (MDR) or extensively drug-resistant (XDR) lactose non-fermenting Gram-negative bacteria such as Pseudomonas aeruginosa and Acinetobacter baumannii . Gap Statement. As the rate of colistin resistance is steadily rising, there is a need for rapid and accurate antimicrobial susceptibility testing methods for colistin. The Rapid ResaPolymyxin Acinetobacter / Pseudomonas NP test has recently been developed for rapid detection of colistin resistance in P. aeruginosa and A. baumannii . Aim. The present study aimed to evaluate the performance of the Rapid ResaPolymyxin Acinetobacter / Pseudomonas NP test in comparison with the reference broth microdilution (BMD) method. Methodology. The Rapid ResaPolymyxin Acinetobacter / Pseudomonas NP test was performed using a total of 135 P . aeruginosa (17 colistin-resistant and 118 colistin-susceptible) and 66 A. baumannii isolates (32 colistin-resistant and 34 colistin-susceptible), in comparison with the reference BMD method. Results. The categorical agreement of the Rapid ResaPolymyxin Acinetobacter / Pseudomonas NP test with the reference BMD method was 97.5 % with a major error rate of 0 % (0/152) and a very major error (VME) rate of 10.2 %. The VME rate was higher (23.5 %) when calculated separately for P. aeruginosa isolates. The overall sensitivity and specificity were 89.8 and 100 %, respectively. Conclusion. The Rapid ResaPolymyxin Acinetobacter / Pseudomonas NP test performed better for A. baumannii than for P. aeruginosa .

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