Gram-negative Clinical Strains Research Articles

Microflora of Secretions in a Surgical Hospital of Orthopedics and Traumatology Profile for 2021-2023 (SI “ITO NAMS of Ukraine”)

Summary. Healthcare-associated infections (HAIs), namely, surgical site infections, early postoperative and subsequent in-hospital infections, are the most common undesirable phenomenon in the world. According to statistics, at least one case of HAIs is diagnosed in every 100 hospitalized patients in hospitals of 7 developed and 15 other countries of the world at any given time. The occurrence of such complications during the treatment of a patient in a hospital leads to the need of additional diagnostic tests, additional courses of antibiotics, and unplanned surgical intervention. Worsening of the prognosis of treatment may occur due to the formation of the so-called resistant microflora in such patients, with a real probability of spreading the infection in the hospital. Prevention of HAIs in practice occurs through planned infection control in operating rooms and procedure rooms in clinical departments and qualified timely diagnostic work of certified microbiological laboratories in hospitals. Objective. The objective of the study was to determine the spectrum of microflora of secretions for three years (2021-2023) in orthopedic and trauma patients due to changes in modern injuries received more often because of military aggression and to propose the identified differences as criteria for prescribing antibacterial drugs in complex inpatient treatment. The work shows that over the past three years (2021-2023), the ratio of gram-positive and gram-negative microorganisms in the study material almost did not change and averaged 1.65. The peculiarity of the analyzed period was an increase in the number of methicillin-resistant staphylococci by 1.3 times. The spectrum of gram-negative clinical strains has changed, namely, the number of Kl.pneumoniae clinical strains with a high level of polyresistance has increased by 2.5 times. The obtained data made it possible to identify the spectrum of microflora of secretions in orthopedic and trauma patients with modern infectious complications, which prompts us to make changes in the standards of antibacterial treatment protocols, and to plan the needs for certain antibiotics in hospitals with personalization of their prescription to improve the effectiveness of treatment and reduce the risk of development of antimicrobial resistance.

In vitro antibacterial activities of cefiderocol against Gram-negative clinical strains isolated from China in 2020

Cefiderocol (CFDC) is a parenteral siderophore cephalosporin that is active against Gram-negative bacteria, including carbapenem-resistant isolates. We report the in vitro activity of CFDC and other antibiotics against 1738 clinical isolates of Gram-negative bacilli (GNB) provided by five medical centres in five provinces of China in 2020 METHODS: Antibiotic susceptibility testing was performed using the Clinical and Laboratory Standards Institute broth microdilution method. Against Pseudomonas aeruginosa and Acinetobacter Spp., the CFDC concentration inhibiting the growth of 90% of the isolates (MIC90) (0.5 μg/mL) was identical and did not change by the carbapenem resistance phenotype. The susceptibility rate of P. aeruginosa and Acinetobacter Spp. to CFDC was high (> 98%) and was similar against isolates with and without meropenem resistance. The MIC of CFDC for all Stenotrophomonas maltophilia isolates (20 isolates) was ≤1 μg/mL and the MIC90 was 0.12 μg/mL. Considerable differences were noted in the susceptibility to CFDC between all tested Enterobacterales isolates and meropenem-non-susceptible Enterobacterales isolates. The MIC90 of CFDC was 1 μg/mL for all tested Enterobacterales isolates and 8 μg/mL for meropenem-non-susceptible Enterobacterales isolates. CFDC demonstrated potent in vitro activity against a recent collection of clinical isolates, including meropenem-non-susceptible isolates, obtained from medical centres in mainland China.

Heteroaryl-Ethylenes as New Effective Agents for High Priority Gram-Positive and Gram-Negative Bacterial Clinical Isolates

The World Health Organization has identified antimicrobial resistance as a public health emergency and developed a global priority pathogens list of antibiotic-resistant bacteria that can be summarized in the acronym ESKAPE (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa and Enterobacterales species), reminding us of their ability to escape the effect of antibacterial drugs. We previously tested new heteroaryl-ethylene compounds in order to define their spectrum of activity and antibacterial capability. Now, we focus our attention on PB4, a compound with promising MIC and MBC values in all conditions tested. In the present study, we evaluate the activity of PB4 on selected samples of ESKAPE isolates from nosocomial infections: 14 S. aureus, 6 E. faecalis, 7 E. faecium, 12 E. coli and 14 A. baumannii. Furthermore, an ATCC control strain was selected for all species tested. The MIC tests were performed according to the standard method. The PB4 MIC values were within very low ranges regardless of bacterial species and resistance profiles: from 0.12 to 2 mg/L for S. aureus, E. faecalis, E. faecium and A. baumannii. For E. coli, the MIC values obtained were slightly higher (4–64 mg/L) but still promising. The PB4 heteroaryl-ethylenic compound was able to counteract the bacterial growth of both high-priority Gram-positive and Gram-negative clinical strains. Our study contributes to the search for new molecules that can fight bacterial infections, in particular those caused by MDR bacteria in hospitals. In the future, it would be interesting to evaluate the activity of PB4 in animal models to test for its toxicity.

Lacticaseicin 30 and Colistin as a Promising Antibiotic Formulation against Gram-Negative β-Lactamase-Producing Strains and Colistin-Resistant Strains.

Antimicrobial resistance is a global health concern across the world and it is foreseen to swell if no actions are taken now. To help curbing this well announced crisis different strategies are announced, and these include the use of antimicrobial peptides (AMP), which are remarkable molecules known for their killing activities towards pathogenic bacteria. Bacteriocins are ribosomally synthesized AMP produced by almost all prokaryotic lineages. Bacteriocins, unlike antibiotics, offer a set of advantages in terms of cytotoxicity towards eukaryotic cells, their mode of action, cross-resistance and impact of microbiota content. Most known bacteriocins are produced by Gram-positive bacteria, and specifically by lactic acid bacteria (LAB). LAB-bacteriocins were steadily reported and characterized for their activity against genetically related Gram-positive bacteria, and seldom against Gram-negative bacteria. The aim of this study is to show that lacticaseicin 30, which is one of the bacteriocins produced by Lacticaseibacillus paracasei CNCM I-5369, is active against Gram-negative clinical strains (Salmonella enterica Enteritidis H10, S. enterica Typhimurium H97, Enterobacter cloacae H51, Escherichia coli H45, E. coli H51, E. coli H66, Klebsiella oxytoca H40, K. pneumoniae H71, K. variicola H77, K. pneumoniae H79, K. pneumoniae H79), whereas antibiotics failed. In addition, lacticaseicin 30 and colistin enabled synergistic interactions towards the aforementioned target Gram-negative clinical strains. Further, the combinations of lacticaseicin 30 and colistin prompted a drastic downregulation of mcr-1 and mcr-9 genes, which are associated with the colistin resistance phenotypes of these clinical strains. This report shows that lacticaseicin 30 is active against Gram-negative clinical strains carrying a rainbow of mcr genes, and the combination of these antimicrobials constitutes a promising therapeutic option that needs to be further exploited.

THE SELECTION OF RESISTANT VARIANTS OF OPPORTUNISTIC MICROORGANISMS USING AETHONIUM IN CLINICS FOR 40 YEARS

vitis. Bukovinian Medical Herald. Т.21, № 3 (83). P. 83-90 THE SELECTION OF RESISTANT VARIANTS OF OPPORTUNISTIC MICROORGANISMS USING AETHONIUM IN CLINICS FOR 40 YEARS L.I. Sydorchuk, I.P. Burdeniuk, S.E. Deineka, K.I. Yakovets, I.Y. Sydorchuk, V.I. Burdeniuk1, K.G. Tashchuk Objective: To establish the minimum bacteriostatic and bactericidal concentration of aethonium in relation to conditionally pathogenic microorganisms isolated and identified from the upper respiratory tract of children aged 11-13 years with chronic catarrhal gingivitis with a comorbid state (type I diabetes mellitus) in a comparative sense with sensitivity to aetonium of reference and clinical strains of conditionally pathogenic microorganisms isolated in 1974-1976. Materials and methods. Primary materials of 1974-1976 years of the sensitivity of conditionally pathogenic microorganisms to aethonium were used from dissertational works of co-authors (I.P. Burdeniuk, I.Y. Sydorchuk) for comparison of data obtained in 2014-2016. Microbiological examinations were performed in 30 pupils aged 11-13 years with catarrhal gingivitis with type I diabetes mellitus. The sampling of the material for microbiological examination was carried out with sterile tampons on the oral mucosa, following by seeding the sectors of solid nutrient media optimal for each taxon to obtain pure cultures. To determine the sensitivity of microbes to aethonium, the method of serial two-fold dilutions in a liquid nutrient medium was used. Results. It is shown that the sensitivity of the reference strains of microorganisms for 40 years of storage under laboratory conditions in a semi-solid nutrient medium remains practically unchanged. The bactericidal concentration of aethonium relative to S. faecalis ATCC 29212 increased by 1,96 %. It was shown that the bacteriostatic and bactericidal activity of aethonium decreased over 40 years relative to clinical strains and this decrease (resistance growth) depends on microorganisms, their morphological, tinctorial and other properties. Grampositive and gram-negative clinical strains of microorganisms have decreased sensitivity from 1,21 to 2,56 times. Conclusions. The development of resistant variants of microorganisms proceeds by gradual selection with dissemination in clinics. Before using aethonium, it is necessary to isolate and identify conditionally pathogenic microbes and to establish the bacteriostatic and bactericidal concentration of aethonium with the subsequent solution of the question of its possible effective use.

In Vitro Antibacterial Activity of S-649266 against Gram-negative Clinical Strains Collected in North America and Europe, 2015

In Vitro Antibacterial Activity of S-649266 against Gram-negative Clinical Strains Collected in North America and Europe, 2015

Polyphenolic extract from maple syrup potentiates antibiotic susceptibility and reduces biofilm formation of pathogenic bacteria.

Phenolic compounds are believed to be promising candidates as complementary therapeutics. Maple syrup, prepared by concentrating the sap from the North American maple tree, is a rich source of natural and process-derived phenolic compounds. In this work, we report the antimicrobial activity of a phenolic-rich maple syrup extract (PRMSE). PRMSE exhibited antimicrobial activity as well as strong synergistic interaction with selected antibiotics against Gram-negative clinical strains of Escherichia coli, Proteus mirabilis, and Pseudomonas aeruginosa. Among the phenolic constituents of PRMSE, catechol exhibited strong synergy with antibiotics as well as with other phenolic components of PRMSE against bacterial growth. At sublethal concentrations, PRMSE and catechol efficiently reduced biofilm formation and increased the susceptibility of bacterial biofilms to antibiotics. In an effort to elucidate the mechanism for the observed synergy with antibiotics, PRMSE was found to increase outer membrane permeability of all bacterial strains and effectively inhibit efflux pump activity. Furthermore, transcriptome analysis revealed that PRMSE significantly repressed multiple-drug resistance genes as well as genes associated with motility, adhesion, biofilm formation, and virulence. Overall, this study provides a proof of concept and starting point for investigating the molecular mechanism of the reported increase in bacterial antibiotic susceptibility in the presence of PRMSE.

Predatory Bacteria: A Potential Ally against Multidrug-Resistant Gram-Negative Pathogens

Multidrug-resistant (MDR) Gram-negative bacteria have emerged as a serious threat to human and animal health. Bdellovibrio spp. and Micavibrio spp. are Gram-negative bacteria that prey on other Gram-negative bacteria. In this study, the ability of Bdellovibrio bacteriovorus and Micavibrio aeruginosavorus to prey on MDR Gram-negative clinical strains was examined. Although the potential use of predatory bacteria to attack MDR pathogens has been suggested, the data supporting these claims is lacking. By conducting predation experiments we have established that predatory bacteria have the capacity to attack clinical strains of a variety of ß-lactamase-producing, MDR Gram-negative bacteria. Our observations indicate that predatory bacteria maintained their ability to prey on MDR bacteria regardless of their antimicrobial resistance, hence, might be used as therapeutic agents where other antimicrobial drugs fail.

Detection of CTX-M type Extended Spectrum Beta Lactamase genes among gram-negative clinical strains isolated from a tertiary care hospital, Mangalore (Karnataka, S.India)

Detection of CTX-M type Extended Spectrum Beta Lactamase genes among gram-negative clinical strains isolated from a tertiary care hospital, Mangalore (Karnataka, S.India)

Analgesic, antibacterial and antiviral activities of 2-(5-alkyl-1,3,4-oxadiazol-2-yl)-3 H -benzo [f] chromen-3-ones

A novel series of 2-(5-alkyl-1,3,4-oxadiazol-2-yl)-3H-benzo[f]chromen-3-ones (4a-e) have been evaluated for analgesic, antibacterial and antiviral activities. Analgesic activity was carried out using acetic acid-induced writhing method in Swiss albino male mice. The antibacterial activity was performed against Gram-positive and Gram-negative clinical strains by agar well diffusion method. The in vitro antiviral activity was carried out against camelpox and buffalopox viruses. The analgesic activity exhibited by the compounds 4a, 4c and 4d were found to be more significant compared to the standard. The bacterial activity was determined by the inhibition of growth of the organism by the drugs at different concentrations. All the compounds showed significant activity when compared with the drug ciprofloxacin. The in vitro antiviral activity of the compound 4b tested against camelpox and buffalopox viruses revealed no activity when tested at concentrations of 250 μg. The compound 4b did not alter the titres of both the viruses and the titres remain, respectively, 106.5 TCID50 and 106.74 TCID50 per ml for camelpox vaccine virus and buffalopox vaccine virus. However, the compounds 4a-e showed significant analgesic and antibacterial activities.

Depsides and Other Polar Constituents from Origanum dictamnus L. and Their in Vitro Antimicrobial Activity in Clinical Strains

Phytochemical investigation of the polar extracts of the aerial parts of Origanum dictamnus afforded 15 secondary metabolites. One new depside was isolated, to which the trivial name salvianolic acid P (1) was given, in addition to the known depsides rosmarinic acid (2) and rosmarinic acid methyl ester (3), as well as two monoterpenes, thymoquinone (4) and thymoquinol 2-O-beta-glucopyranoside (5); two simple phenolic acids, oresbiusin A (6) and E-caffeic acid (7); six flavonoids, namely, apigenin (8), kaempferol (9), quercetin (10), eriodictyol (11), taxifolin (12), naringenin (13); and two alicyclic derivatives, that is, 12-hydroxyjasmonic acid (14) and its 12-O-beta-d-glucoside (15). The structures of all isolated compounds were established by spectroscopic methods, mainly 1D and 2D NMR, as well as HPLC-DAD-MS and HR-MS spectrometric analyses. The absolute configuration of compound 1 was determined by CD measurements as 7'R, 7''S, 8''S. Compound 1 is interesting as it contains a benzodioxane ring, which is unusual in natural products. Moreover, it has been proved to be active against the Gram-negative clinical strains Acinetobacter hemolyticus , Empedobacter brevis , Pseudomonas aeruginosa , and Klebsiella pneumoniae .

Antimicrobial activity of beta-lactam antibiotics against clinical pathogens after molecular inclusion in several cyclodextrins. A novel approach to bacterial resistance.

Recognition and uptake by specific cellular receptors and transport systems for cyclodextrins have been demonstrated. Based on this concept, natural and synthetically modified cyclodextrins were used as drug carriers. Several beta-lactam antibiotics were selected and their inclusion complexes with different cyclodextrins were prepared (molar ratio ranging from 1:1 to 1:3). The complex formation, in aqueous solution, was monitored and optimum complexation conditions were selected. The inclusion of the active molecules in the cyclodextrin cavity was confirmed by (1)H NMR spectroscopy. Specific HPLC methods for the quantitation of antibiotics in the presence of cyclodextrins were developed and their chemical stability under complexation conditions was confirmed. Antimicrobial activity of drug-cyclodextrin complexes, in terms of minimum inhibitory concentration (MIC), were compared with the corresponding values of uncomplexed free molecules. A wide range of clinical pathogens and known beta-lactamase-producing strains were tested. The activity of the cyclodextrin-included antibiotics was increased, particularly against Gram-negative clinical strains. The nature and degree of substitution on cyclodextrin macromolecules may be the predominant factor in the observed improvement in antimicrobial activity. We believe that the proposed methodology is a novel approach to the microbial resistance problem and will trigger research towards the development of new cyclodextrin derivatives bearing the ability to increase the uptake of included antimicrobial molecules through intensification of the corresponding molecular recognition phenomena.

Direct Comparison of the BD Phoenix System with the MicroScan WalkAway System for Identification and Antimicrobial Susceptibility Testing of Enterobacteriaceae and Nonfermentative Gram-Negative Organisms

The Phoenix automated microbiology system (BD Diagnostics, Sparks, MD) is designed for the rapid identification (ID) and antimicrobial susceptibility testing (AST) of clinically significant human bacterial pathogens. We evaluated the performance of the Phoenix instrument in comparison with that of the MicroScan WalkAway system (Dade Behring, West Sacramento, CA) in the ID and AST of gram-negative clinical strains and challenge isolates of Enterobacteriaceae (n = 150) and nonfermentative gram-negative bacilli (NFGNB; 45 clinical isolates and 8 challenge isolates). ID discrepancies were resolved with the API 20E and API 20NE conventional biochemical ID systems (bioMerieux, Durham, NC). The standard disk diffusion method was used to resolve discordant AST results. The overall percentages of agreement between the Phoenix ID results and the MicroScan results at the genus and species levels for clinical isolates of Enterobacteriaceae were 98.7 and 97.7%, respectively; following resolution with conventional biochemical testing, the accuracy of the Phoenix system was determined to be 100%. For NFGNB, the levels of agreement were 100 and 97.7%, respectively. Both systems incorrectly identified the majority of the uncommon nonfermentative nonpseudomonal challenge isolates recovered from cystic fibrosis patients; these isolates are not included in the databases of the respective systems. For AST of Enterobacteriaceae, the rate of complete agreement between the Phoenix results and the MicroScan results was 97%; the rates of very major, major, and minor errors were 0.3, 0.2, and 2.7%, respectively. For NFGNB, the rate of complete agreement between the Phoenix results and the MicroScan results was 89.1%; the rates of very major, major, and minor errors were 0, 0.5, and 7.7%, respectively. Following the confirmatory testing of nine clinical isolates initially screened by the MicroScan system as possible extended-spectrum-beta-lactamase (ESBL)-producing organisms (seven Klebsiella pneumoniae isolates and two Escherichia coli isolates), complete agreement was achieved for eight isolates (one ESBL positive and seven negative); one false positive was obtained with the Phoenix instrument. The MicroScan system correctly detected the 10 ESBL challenge isolates, versus the 6 detected by the Phoenix system. Overall, there was good correlation between the Phoenix instrument and the MicroScan system for the ID and AST of Enterobacteriaceae and common NFGNB. The Phoenix system is a reliable method for the ID and AST of the majority of clinical strains encountered in the clinical microbiology laboratory. Until additional performance data are available, results for all Klebsiella pneumoniae or Klebsiella oxytoca and E. coli isolates screened and confirmed as ESBL producers by any automated system should be confirmed by alternate methods prior to the release of final results.

Prevalence and Expression of the Plasmid-Mediated Quinolone Resistance Determinant qnrA1

Since its discovery, qnrA has been found in most common Enterobacteriaceae. Ciprofloxacin MICs conferred by different qnrA-positive plasmids could range from 0.1 microg/ml to 2 microg/ml in Escherichia coli J53. The reasons for different ciprofloxacin MICs conferred by qnrA have not been fully clarified. Five hundred forty-one consecutive gram-negative clinical strains that were resistant or intermediate to ciprofloxacin and that were isolated in Shanghai in 2005 were screened for qnrA by PCR. For qnrA-positive isolates, the transferability of quinolone resistance was determined by conjugation and mutations within the quinolone resistance-determining region (QRDR) of gyrA and parC. aac(6')-Ib-cr was detected and qnrA RNA expression was determined using real-time reverse transcription-PCR for transconjugants with different ciprofloxacin MICs. The qnrA gene was detected in 7 of the 541 clinical isolates. Quinolone resistance was transferred in four strains by conjugation. Mutations in the QRDR of gyrA and parC were detected in five qnrA-positive clinical strains with higher ciprofloxacin MICs. Of four qnrA-bearing plasmids in E. coli J53, pHS4 and pHS5 conferred ciprofloxacin MICs of 0.094 to 0.125 microg/ml; pHS3, which harbored the aac(6')-Ib-cr gene as well, conferred a ciprofloxacin MIC of 0.25 microg/ml, and pHS6, which had both the aac(6')-Ib-cr gene and a high expression level of qnrA, had a ciprofloxacin MIC of 1.0 microg/ml. The prevalence of qnrA appeared to be higher in Enterobacter cloacae than in other Enterobacteriaceae. The coexistence of qnrA and aac(6')-Ib-cr in a single plasmid and increased qnrA expression can account for the different levels of ciprofloxacin resistance seen in transconjugants.

Antimicrobial activity of cefepime tested against ceftazidime-resistant Gram-negative clinical strains from North American Hospitals: report from the SENTRY Antimicrobial Surveillance Program (1998–2004)

To assess the effect of ceftazidime resistance on the activity of other antimicrobial agents, 3030 ceftazidime-resistant Gram-negative bacilli (GNB) isolates (of a total of 42 061 GNB) were tested against a panel of more than 30 agents. Ceftazidime resistance was observed in 40.3% of Acinetobacter spp., 16.9% of Pseudomonas aeruginosa, and 5.7% of Enterobacteriaceae isolates. The highest rates of ceftazidime resistance among the enteric GNB were observed with Enterobacter spp. (20.9%) > Citrobacter spp. (15.3%) > indole-positive Proteae (10.1%). Overall, 90% of ceftazidime-resistant Enterobacteriaceae and 30% of ceftazidime-resistant P. aeruginosa remained susceptible to the “4th-generation” cephalosporin, cefepime. The activities (% susceptible) of other antimicrobials tested against ceftazidime-resistant Enterobacteriaceae and P. aeruginosa, respectively, were as follows: amikacin, 90% and 88%; ciprofloxacin, 63% and 46%; gentamicin, 59% and 67%, imipenem, 99% and 65%; levofloxacin, 69% and 44%; and piperacillin/tazobactam only 40% and 12%. Ceftazidime-resistant GNB exhibited high rates of resistance to other antimicrobials. Cefepime was very active against ceftazidime-resistant enteric GNB (AmpC enzyme producers), especially Enterobacter spp. (94.3% susceptible), Citrobacter spp. (96.7% susceptible), and indole-positive Proteae (89.6% susceptible), and showed activity similar to that of ceftazidime against all P. aeruginosa and Acinetobacter spp. isolated in North American medical centers. Continued resistances surveillance monitoring will be necessary to assess the effectiveness of widely used broad-spectrum antimicrobials as novel resistance mechanisms emerge.

Sensitive EDTA-Based Microbiological Assays for Detection of Metallo-β-Lactamases in Nonfermentative Gram-Negative Bacteria

The worldwide spread of metallo-beta-lactamase (MBL)-producing gram-negative bacilli represents a great concern nowadays. Sensitive assays for their specific detection are increasingly demanded to aid infection control and to prevent their dissemination. We have developed a novel microbiological assay employing crude bacterial extracts, designated EDTA-imipenem microbiological assay (EIM), to identify MBLs in nonfermentative gram-negative clinical strains. We also evaluated the ability of EIM to detect MBLs in comparison to those of other currently employed screening methods, such as the EDTA disk synergy test (EDS) with imipenem as a substrate and the Etest method. The sensitivities of EIM and Etest were similar (1 versus 0.92, respectively) and much higher than that of EDS (0.67). Moreover, both EIM and Etest displayed the maximum specificity. Modifications were introduced to EDS, including the simultaneous testing of three different beta-lactams (imipenem, meropenem, and ceftazidime) and two different EDTA concentrations. This resulted in a sensitivity improvement (0.92), albeit at a cost to its specificity. A simple strategy to accurately detect MBL producers is proposed; this strategy combines (i) an initial screening of the isolates by the extended EDS assay to select the potential candidates and (ii) confirmation of the true presence of MBL activity by EIM.

Detection of heat shock proteins but not superantigen by isolated oral bacteria from patients with Behcet's disease

We isolated bacteria from periodontal sites and mixed saliva in eight patients with Behcet's disease and surveyed them to determine whether they produced heat shock proteins (HSPs) and superantigen. Cultivable bacterial compositions from periodontal sites and saliva were examined by anaerobic culture using blood agar plates. Gram-negative anaerobic rods such as Prevotella intermedia, Fusobacterium nucleatum, and Capnocytophaga species were predominant in the isolates from the subgingival plaque samples. The Streptococcus mitis group was the most common type isolated from the saliva samples. To detect the production of HSPs, Western blot analyses were performed using a polyclonal rabbit antibody to Escherichia coli DnaK and a monoclonal antibody to Helicobacter pylori Gro-EL. Sonic extracts of 27 of the strains (79.4%) reacted with the antibody against E. coli DnaK. Nine of these 34 strains (26.5%) were found to produce HSPs that reacted with antibody to H. pylori Gro-EL. A total of 54 isolates were examined for superantigen activity against human peripheral leukocytes. Twenty-five gram-negative clinical strains isolated from chronic periodontitis lesions and 20 ATCC strains of microorganisms were also examined. We could not detect any superantigen activity in 500x diluted supernatant of the strains isolated from the eight patients with Behcet's disease. The present study indicates that the anaerobic strains isolated from the oral cavity of these patients produce HSPs, the production being related to Bechet's disease.