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PubMed1988

Occurrence of the Campylobacter resistance gene tetO in Enterococcus and Streptococcus spp.

The distribution of nucleotide sequences related to tetK, tetL, tetM, and tetO was studied by dot blot hybridization in 178 strains of Streptococcus and Enterococcus spp. that were resistant to tetracycline. The tetO gene, which is responsible for tetracycline resistance in Campylobacter spp., was detected in six Streptococcus strains and two Enterococcus strains, in which it was borne by similar plasmids. This observation confirms our previous proposal that tetO originated in gram-positive cocci. tetM, the most prevalent resistance gene, was present alone in 109 strains and associated with tetL in 33 strains in which the two genes contributed cooperatively to high-level tetracycline resistance. tetL was present alone in five Enterococcus strains, and tetK was detected in a single Streptococcus strain. The existence of 22 strains that did not hybridize to the probes suggest that tetracycline resistance in streptococci and enterococci involves additional gene classes as well.

Campylobacter↗
PubMed1978

[Clinical significance of common anaerobes in pyogenic infections of the female genitalia].

From 1972-1977 one hundred and fouteen pyogenic infections of gynaecologic and obstetric patients at UFK Halle had retrospectively been examined. 168 isolations were analysed. By improving the methods of taking away, transporting and bacteriologic cultivation the specimens anaerobic organisms were recovered in 67.3% of all positive results. The pathogenic importance of them is being emphasized by 30,8% of anaerobic monoinfections. The difficult culture of these microogranisms requires a close cooperation between hospital and the place of research. In the treatment surgical operative measures often are preferred to use of chemotherapeutica because of the latter is characterized by a distinctive resistance against numerous antibiotica. This is especially characteristics of Genus Bacteroides besides E. coli the most isolated organism of all.

Anaerobiosis↗
PubMed2006

The influence of modified atmospheres and their interaction with water activity on the radial growth and fumonisin B(1) production of Fusarium verticillioides and F. proliferatum on corn. Part II: The effect of initial headspace oxygen concentration.

This paper is the second in a series of two that describe the effect of modified atmospheres on the growth and mycotoxin production of Fusarium verticillioides and Fusarium proliferatum on corn. In this part, the effect of initial headspace (IH) oxygen concentration and its interaction with water activity (a(w)) on growth and fumonisin B(1) production was investigated. In addition, the impact of vacuum packaging and in-cooperation of O(2) scrubbing sachets was also studied. It was observed that at all a(w) values studied, reduction of IH O(2) concentration from 20 to 2% had no significant effect on the colony growth rate (g, mm d(-1)) and lag phase duration (lambda, d). However, g and lambda were positively and negatively correlated to a(w). The IH O(2) concentration was determined to have a a(w) dependent effect on the oxygen consumption rate. Although the maximum colony diameter (D(max), mm) decreased with the reduction of the IH O(2) level, the greatest mycelial density occurred at 10% IH O(2) for both isolates. This observation was accompanied by a trend of a decrease in the value of the IH O(2) level at which the most fumonisin B(1) was produced from 15 to 5% when the a(w) was decreased from 0.976 to 0.930 for F. verticillioides. For F. proliferatum the optimum conditions for fumonisin B(1) production shifted from 20% at a(w) 0.976 to 10% at both 0.951 and 0.930. Vacuum packaging and the in-cooperation of O(2) absorbing sachets completely inhibited the growth of both isolates. These results together with those reported in Part I of the study indicate that O(2) should preferably be completely excluded from modified atmospheres that are employed to protect stored corn from fungal growth and mycotoxin production.

Colony Count, Microbial↗
PubMed2026

Microbiological analysis and whole-genome sequencing of Neisseria gonorrhoeae from the microbiological failures in the international, zoliflodacin, phase 3, clinical trial for treatment of uncomplicated urogenital gonorrhoea: a retrospective, genomic, observational study.

BACKGROUND: Zoliflodacin, a first-in-class oral bacterial, DNA gyrase (GyrB) inhibitor, showed non-inferiority to ceftriaxone combined with azithromycin in a recent large international, phase 3, randomised controlled trial for treatment of uncomplicated urogenital gonorrhoea. The aim of this study was to describe the microbiological and whole-genome sequencing (WGS) analyses of paired baseline (pre-treatment) and test-of-cure (TOC) gonococcal isolates from the zoliflodacin phase 3, randomised controlled trial to further characterise and evaluate the protocol-specified microbiological failures with zoliflodacin (n=22) or ceftriaxone and azithromycin (n=1). METHODS: In this retrospective, genomic, observational study, results from antimicrobial susceptibility testing (agar dilution method) of isolates (n=960; 936 baseline isolates from 763 participants and 24 TOC isolates [23 with a paired baseline isolate in the same anatomical site] from 20 participants) collected during the zoliflodacin phase 3, randomised controlled trial done in 16 outpatient clinics in Belgium, the Netherlands, South Africa, Thailand, and the USA (Nov 6, 2019-March 16, 2023) are described. WGS analysis was performed on paired baseline and TOC isolates from participants with microbiological failures (zoliflodacin 44 isolates [19 participants]; ceftriaxone and azithromycin two isolates [one participant]), and the three baseline isolates with highest zoliflodacin minimum inhibitory concentration (MIC 0·5 mg/L). FINDINGS: All isolates were inhibited by the same zoliflodacin concentrations (MICs ≤0·008 to 0·5 mg/L) as wild-type strains cultured internationally in 2013-23. In participants with a microbiological failure after zoliflodacin treatment (n=22, 19 participants), zoliflodacin MIC values for baseline and TOC isolates were similar, and resistance selection was lacking. WGS showed that five (23%) of 22 infections (95% CI 10-43 [in four participants]) of zoliflodacin microbiological failures had different strains at TOC versus baseline. In 17 zoliflodacin microbiological failures (15 participants), isolates at baseline and TOC were indistinguishable. 13 of these 17 microbiological failures, corresponding to 59% (95% CI 39-77; 13 of 22) of all zoliflodacin microbiological failures, were in urogenital or rectal sites in 11 participants and the isolates had zoliflodacin MICs less than or equal to 0·008 to 0·25 mg/L. The single microbiological failure after ceftriaxone and azithromycin treatment had different strains at TOC versus at baseline. No sequenced isolates had mutations associated with elevated zoliflodacin MICs. INTERPRETATION: In the zoliflodacin phase 3, randomised controlled trial, 23% of the zoliflodacin microbiological failures and the single ceftriaxone and azithromycin microbiological failure had different gonococcal strains at TOC versus baseline, which suggests reinfections and not treatment failures. In addition, 59% of the zoliflodacin microbiological failures, all in anogenital sites, had no obvious microbiological explanation based on the low zoliflodacin MICs, previous pharmacodynamic studies, and no evidence of resistance selection after zoliflodacin therapy. A reinfection as the cause for these microbiological failures could not be excluded. We recommend that WGS is implemented in future randomised controlled trials for gonorrhoea treatment to further evaluate possible microbiological failures, exclude reinfections (to avoid underestimating the cure rates), and characterise antimicrobial resistance determinants. FUNDING: GARDP through grants from Germany BMFTR (03KA1831), UK DHSC as part of GAMRIF, Japan MHLW, the Netherlands' Ministry of Health, Welfare and Sport and Directorate-General for International Cooperation, the Federal Office of Public Health of Switzerland, the Canton of Geneva, Switzerland, and Örebro University Hospital, Sweden.

Humans↗
PubMed1997

Sulfated carbohydrate compounds prevent microbial adherence by sexually transmitted disease pathogens.

Heparan sulfate (HS) serves as a receptor for adherence of herpes simplex viruses, Chlamydia trachomatis, Neisseria gonorrhoeae, and, indirectly, human immunodeficiency virus. Using primary human culture systems, we identified sulfated carbohydrate compounds that resemble HS and competitively inhibit infection by these pathogens. These compounds are candidates for intravaginal formulations for the prevention of sexually transmitted diseases.

Bacterial Adhesion↗
PubMed1983

Quality control parameters for susceptibility tests with 30-micrograms netilmicin disks.

A nine-laboratory cooperative study was performed to evaluate quality control parameters for susceptibility tests with 30-micrograms netilmicin disks. The applicability of currently recommended zone-size limits was confirmed. However, alternative statistical methods suggested that tighter control limits might be more appropriate but would require better standardization of reagents, especially Mueller-Hinton agars.

Agar↗
PubMed2000

Heterogeneity in biofilms.

Biofilms, accumulations of microorganisms at interfaces, have been described for every aqueous system supporting life. The structure of these microbial communities ranges from monolayers of scattered single cells to thick, mucous structures of macroscopic dimensions (microbial mats; algal-microbial associations; trickling filter biofilms). During recent years the structure of biofilms from many different environments has been documented and evaluated by use of a broad variety of microscopic, physico-chemical and molecular biological techniques, revealing a generally complex 3D structure. Parallel to these investigations more and more complex mathematical models and simulations were developed to explain the development, structures, and interactions of biofilms. The forces determining the spatial structure of biofilms, including microcolonies, extracellular polymeric substances (EPS), and channels, are still the subject of controversy. To achieve conclusive explanations for the structures observed in biofilms the cooperation of both fields of investigation, modelling and experimental research, is necessary. The expanding field of molecular techniques not only allows more and more detailed documentation of the spatial distribution of species, but also of functional activities of single cells in their biofilm environment. These new methods will certainly reveal new insights in the mechanisms involved in the developmental processes involved in the formation and behavior of biofilms.

Bacteria↗
PubMed2006

The B-cell system in inflammatory bowel disease.

Secretory immunity is the best-defined part ot the mucosal immune system. This adaptive humoral defense mechanism depends on a fine-tuned cooperation between secretory epithelia and local plasma cells. Such mucosal immunocytes produce preferentially dimers and larger polymers of immunoglobulin A (collectively called pIgA), which contain J chain and therefore can bind to the epithelial secretory component (SC). This transmembrane glycoprotein functions as pIg receptor (pIgR) that also translocates pentameric IgM to the epithelial surface. B cells with a high level of J-chain expression and pIg-pIgR interactions at mucosal effector sites are thus necessary for the generation of secretory antibodies (SIgA and SIgM). Secretory antibodies perform immune exclusion in a first-line defense, thereby counteracting microbial colonization and mucosal penetration of soluble antigens. However, local production of pIgA is significantly down-regulated in inflammatory bowel disease (IBD), as revealed by strikingly decreased J-chain expression. Although the total increase of the immunocyte population in IBD lesions probably compensates for the relatively reduced pIgA production, decreased pIgR/SC expression in regenerating and dysplastic epithelium signifies that the SIgA system is topically deficient. There is, moreover, a significant shift from IgA2 to IgA1 production, the latter subclass being less resistant to proteolytic degradation. These changes--together with activation of mucosal macrophages and a dramatic increase of IgG-producing cells--may reflect local establishment of a second defense line which, however, is unsuccessful in its attempt to eliminate antigens derived from the indigenous microbial flora. Such a 'frustrated' local humoral immune system results in altered immunological homeostasis and jeopardized mucosal integrity. Complement activation observed in relation to epithelium-bound IgG1 in ulcerative colitis indicates, moreover, that the surface epithelium is subjected to immunological attack by an autoimmune reaction. These luminal deposits regularly contain terminal cytotoxic complement, and often also C3b as a sign of persistent activation. Comparison of identical twins, discordant with regard to ulcerative colitis, suggests that the markedly skewed local IgG1 response seen in this IBD entity may be genetically determined. The initial event(s) eliciting B-cell driven immunopathology in IBD remains unknown. Abrogation of oral tolerance to certain antigens from commensal bacteria has been suggested as a putative early mechanism, and lymphoid neogenesis and hyperplasia in the lesions most likely signify massive microbial overstimulation of the local B-cell system. Such ectopic lymphoid microcompartments may contribute substantially to the proinflammatory systemic-type of B-cell responses occurring in established IBD lesions.

Animals↗
PubMed2000

Collectins and pulmonary innate immunity.

The surfactant-associated proteins SP-A and SP-D are members of a family of host defense lectins, designated collectins. There is increasing evidence that these pulmonary, epithelial-derived proteins are important components of the innate immune response to microbial challenge and participate in other aspects of immune and inflammatory regulation within the lung. Both proteins bind to glycoconjugates and/or lipid moieties expressed by a wide variety of microorganisms, and to certain organic particles, such as pollens. SP-A and SP-D have the capacity to modulate leukocyte function and, in some circumstances; to opsonize and enhance the killing of microorganisms. The biologic activity of cell wall components, such as Gram-negative bacterial polysaccharides, or viral glycoproteins, such as the hemagglutinin of influenza viruses, may be altered by interactions with collectins. In addition, complementary or cooperative interactions between SP-A, SP-D and other host defense lectins could contribute to the efficiency of this defense system. Collectins could play particularly important roles in settings of inadequate or impaired specific immunity, and acquired alterations in the levels of active collectins within the airspaces and distal airways may increase susceptibility to infection.

Bacterial Infections↗
PubMed1999

Activation of particulate guanylyl cyclase by Vibrio vulnificus hemolysin.

Recently we reported that Vibrio vulnificus hemolysin, an exotoxin produced by V. vulnificus, dilates rat thoracic aorta via elevated cGMP levels without affecting nitric oxide synthase. We investigated the mechanism further by observing the guanylyl cyclase activities in cytosolic, membrane, unfractionated, or reconstituted preparations. Hemolysin did not activate guanylyl cyclase in the membrane or cytosolic fraction, while it activated guanylyl cyclase in unfractionated or reconstituted preparation. The increased activity was not inhibited by the HS-142-1, a microbial polysaccharide which antagonizes atrial natriuretic peptide receptor, or 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ), a soluble guanylyl cyclase inhibitor. However, it was attenuated by 6-(phenylamino)-5,8-quinolinedione (LY 83.583), which inhibits the catalytic domain of both guanylyl cyclases, and by cholesterol, which blocks hemolysin-incorporation into the membrane. Removing ATP, a cofactor of particulate guanylyl cyclase, attenuated the activation and ATPgammaS, a non-phosphorylating analog, restored it. These results suggest that V. vulnificus hemolysin activates particulate guanylyl cyclase via hemolysin incorporation into the vascular smooth muscle cell membrane in cooperation with certain unidentified cytosolic component(s).

Adenosine Triphosphate↗
PubMed2005

Effective communication of antimicrobial susceptibility data by pathologists to clinicians.

As antimicrobial-resistant gram-positive and gram-negative bacterial infections continue to emerge over time, influenced by selective pressure, and the costs of treating these infections increase, the ability of microbiology laboratories to accurately detect drug resistant bacteria and communicate susceptibility test results effectively to clinicians in a timely manner is more important than ever. Ongoing cooperation and coordination of activities among clinical pathologists, technical personnel, pharmacy, clinical services, and infection control using up-to-date laboratory methodologies and interpretive criteria to develop laboratory reports that are transmitted efficiently through computerized communication systems for use within each particular institution are essential to provide optimum patient care, control resistance, and conserve resources.

Clinical Laboratory Information Systems↗
PubMed1975

Studies on energy-linked reactions: isolation, characterisation and genetic analysis of trialkyl-tin-resistant mutants of Saccharomyces cerevisiae.

Mutants of Saccharomyces cerevisiae resistant to triethyl tin sulphate have been isolated and are cross-resistant to other trialkyl tin salts. Triethyl-tin-resistant mutants fall into two general phenotypic classes: class 1 and class 2. Class 1 mutants are cross-resistant to a variety of inhibitors and uncoupling agents which affect mitochondrial membranes (oligomycin, ossamycin, valinomycin, antimycin, erythromycin, chloramphenicol, '1799', tetrachlorotrifluoromethyl benzimidazole carbonylcyanide-m-chlorophenylhydrazone and cycloheximide). Class 2 mutants are specifically resistant to trithyl tin and the uncoupling agent "1799' [bis-(hexafluoroacetonyl)-acetone]. Triethyl tin at neutral pH values is a specific inhibitor of mitochondrial energy conservation reactions and prevents growth on oxidisable substrates such as glycerol and ethanol. Triethyl-tin-resistant mutants grow normally on glucose and ethanol in the presence of triethyl tin (10 muM). Biochemical studies indicate that the mutation involves a modification of the triethyl tin binding site on the mitochondrial inner membrane, probably the ATP-synthetase complex. Triethyl tin resistance/sensitivity in yeast is determined by cytoplasmic (mitochondrial) and nuclear genes. The mutants fall into a nuclear and a cytoplasmic (mitochondrial) class corresponding to the phenotypic cross-resistance classes 1 and 2. In the cytoplasmic mutants the triethyl tin resistance segregates mitotically and the resistance determinat is deleted by the action of ethidium bromide during petite induction. Recombination studies indicate that the triethyl tin mutations are not allelic with the other mitochondrial mutations at the loci RI, RIII and OLI. This indicates that the binding or inhibitory sites of oligomycin and triethyl tin are not identical and that the triethyl tin binding site is located on a different mitochondrial gene product to those which are involved in oligomycin binding. Interaction and cooperative effects between different binding sites on the mitochondrial inner membrane have been demonstrated in studies of the effect of the insertion of the TETr phenotype into mitochondrial oligomycin-resistant mutants and provide an experimental basis for complementation studies at the ATP-synthetase level.

Adenosine Triphosphatases↗
PubMed1975

[Present status and treatment of urogenital tuberculosis].

Urogenital tuberculosis has not decreased in incidence like other forms of tuberculosis and this is not to be expected in the coming years. Following combined modern chemotherapy the chances of conversion and also clinical cure are increased. The patient's cooperation during a systematic triple drug therapy in adequate dosage is important. The possibility of ambulatory treatment will depend on the clinical findings and the patient's social situation. Physical and occupational therapy and early resocialization of the patient are important. Prolonged unemployment should be avoided. Urological care of the patient is particularly important in the early phases of the treatment.

Drug Resistance, Microbial↗
PubMed2004

Neutrophils and keratinocytes in innate immunity--cooperative actions to provide antimicrobial defense at the right time and place.

The human neutrophil is a professional phagocyte of fundamental importance for defense against microorganisms, as witnessed by the life-threatening infections occurring in patients with neutropenia or with defects that result in decreased microbicidal activity of the neutrophil. Likewise, the skin and mucosal surfaces provide important barriers against infections. Traditionally, these major defense systems, the epithelial cells and the neutrophils, have been viewed as limited in their armory: The epithelial cells provide defense by constituting a physical barrier, and the neutrophils provide instant delivery of preformed antimicrobial substances or on-the-spot assembly of the multicomponent reduced nicotinamide adenine dinucleotide phosphate oxidase from stored components for the generation of reactive oxygen metabolites. Recent research has shown that epithelial cells are highly dynamic and able to generate antimicrobial peptides in response not only to microbial infection itself but more importantly, to the growth factors that are called into play when the physical barrier is broken, and the risk of microbial infection is imminent. Likewise, the neutrophil changes its profile of actively transcribed genes when it diapedeses into wounded skin. This results in generation of signaling molecules, some of which support the growth and antimicrobial potential of keratinocytes and epithelial cells. This paper will highlight some recent advances in this field.

Acute-Phase Proteins↗
PubMed2003

Mechanism of action of oritavancin and related glycopeptide antibiotics.

Oritavancin (LY333328) is a semisynthetic glycopeptide antibiotic having excellent bactericidal activity against glycopeptide-susceptible and -resistant Gram-positive bacteria. Oritavancin is the N-alkyl-p-chlorophenylbenzyl derivative of chloroeremomycin (LY264826) and is currently in phase III clinical trials for use in Gram-positive infections. Studies show that oritavancin and related alkyl glycopeptides inhibit bacterial cell wall formation by blocking the transglycosylation step in peptidoglycan biosynthesis in a substrate-dependent manner. As with other glycopeptide antibiotics, including vancomycin, the effects of oritavancin on cell wall synthesis are attributable to interactions with dipeptidyl residues of peptidoglycan precursors. Unlike vancomycin, however, oritavancin is strongly dimerized and can anchor to the cytoplasmic membrane, the latter facilitated by its alkyl side chain. Cooperative interactions derived from dimerization and membrane anchoring in situ can be of sufficient strength to enable binding to either dipeptidyl or didepsipeptidyl peptidoglycan residues of vancomycin-susceptible and -resistant enterococci, respectively. This review describes the antibacterial activity of oritavancin, and examines the evidence supporting the proposed mechanism of action for this agent and related analogs.

Anti-Bacterial Agents↗
PubMed1993

An overview of nosocomial infections, including the role of the microbiology laboratory.

An estimated 2 million patients develop nosocomial infections in the United States annually. The increasing number of antimicrobial agent-resistant pathogens and high-risk patients in hospitals are challenges to progress in preventing and controlling these infections. While Escherichia coli and Staphylococcus aureus remain the most common pathogens isolated overall from nosocomial infections, coagulase-negative staphylococci (CoNS), organisms previously considered contaminants in most cultures, are now the predominant pathogens in bloodstream infections. The growing number of antimicrobial agent-resistant organisms is troublesome, particularly vancomycin-resistant CoNS and Enterococcus spp. and Pseudomonas aeruginosa resistant to imipenem. The active involvement and cooperation of the microbiology laboratory are important to the infection control program, particularly in surveillance and the use of laboratory services for epidemiologic purposes. Surveillance is used to identify possible infection problems, monitor infection trends, and assess the quality of care in the hospital. It requires high-quality laboratory data that are timely and easily accessible.

Bacterial Infections↗
PubMed1993

Anthrotainin, an inhibitor of substance P binding produced by Gliocladium catenulatum.

Substance P (SP) is an undecapeptide belonging to a family of chemically related neurotransmitters and neuromodulators known as neurokinins. In our search for SP antagonists, we screened microbial broth extracts for the ability to inhibit radiolabeled SP binding to membranes prepared from rat forebrain. Anthrotainin was isolated from a fungal culture and determined to be a novel tetracyclic compound, with an IC50 of 3 microM against [125I]SP. The structure, spectroscopic, chemical, and pharmacological properties of anthrotainin are presented.

Animals↗
PubMed1995

Limitations, definitions, principles and methods of risk analysis.

Decisions on veterinary biologicals involve large uncertainties, complexities which cut across many scientific and technical disciplines, and large potential adverse impacts on public health and on important sectors of the economy. How should risk assessment help to guide the decision process on veterinary biologicals? How can risk assessment practices be harmonized internationally, given the different regulatory traditions and institutions of different countries? A broad view of risk assessment is needed, that risk assessment is a framework for summarizing applicable scientific judgement in support of regulatory decision-making. Support for this view of risk assessment is found in the major reports which have defined risk assessment as currently practised by many regulatory agencies in the United States of America (USA). However, some interested and affected parties perceive risk assessment in the USA as overly quantitative and narrowly focused on regulatory standards for carcinogens. An example of risk assessment for microbial contamination indicates how quantitative methods can be used when data are sparse and decisions must be made in the face of great uncertainty. Such quantitative methods can be used to improve communication about risk, to promote consensus in support of controversial decisions, and to identify valuable opportunities for research to reduce the important sources of uncertainty.

Animals↗