Meningococcal disease and future drug targets

Neisseria meningitidis (N. meningitidis) causes sepsis, epidemic meningitis, and sometimes also meningoencephalitis. Despite early antibiotic treatment, mortality and morbidity remain significant. We present recent studies on meningococcal disease with focus on the pathophysiology caused by bacterial virulence factors and the host immune responses. The bacterial outer membrane lipopolysaccharide and non-lipopolysaccharide components are related to meningococcal adhesion and invasion, while the host immune reactions propagate inflammation and neurodegeneration. Hence, bacterium-host interactions are key determinants of the clinical course and risk of fatal outcome. Accordingly, successful treatment of severe meningococcal disease requires not only antibiotics but also adjuvants targeting the released endotoxins and the host immune/inflammatory responses. This review highlights the most recent data and current knowledge on molecular mechanisms of meningococcal disease and explains how host immune responses ultimately may aggravate neuropathology and the clinical prognosis. Within this context, particular importance is paid to the endotoxic components that provide potential drug targets for novel neuroprotective adjuvants, which are needed in order to improve the clinical management of meningoencephalitis and patient prognosis.

Performance of PCR-restriction fragment length polymorphism analysis of the Helicobacter pylori ureB gene in differentiating gene variants

Recently, PCR-restriction fragment length polymorphism (PCR-RFLP) of the urease genes of Helicobacter pylori was evaluated in a meta-analysis; acceptable discriminatory indices of the ureAB and C genes were found. In the present investigation, we found a discriminatory index of 0.95 for 191 unrelated clinical H. pylori isolates with PCR-RFLP typing of the ureB gene (933 bp), combining the results obtained with restriction enzymes HaeIII and Sau3A, and a mixture of the enzymes. We therefore find that PCR-RFLP typing of the ureB gene of H. pylori with restriction enzymes HaeIII and Sau3A is comparable to typing of other H. pylori urease genes.

[Hygiene in general practice]

The purpose of this study was to examine how general practitioners handle infection control precautions. The study is based on interviews with 26 general practitioners. The following subjects were included: hand washing, skin disinfection of the patients before injections and minor surgery and disinfection and sterilisation procedures of the instruments. The investigation demonstrated that the precautions varied widely. A manual describing simple and safe infection control precautions in the outpatient setting has been written.

Molecular methods for typing of Helicobacter pylori and their applications

Microbial typing is a useful tool in clinical epidemiology for defining the source and route of infection, for studying the persistence and reinfection rates, clonal selection in the host and bacterial evolution. Phenotypic methods such as biotyping, serotyping and hemagglutinin typing have little discriminatory power compared to genotypic methods concerning the typing of Helicobacter pylori. Therefore great efforts have been made to establish useful molecular typing methods. In this context, the most frequently used genotypic methods are described based on our own experience and the literature: (1) restriction endonuclease analysis, (2) endonuclease analysis using pulsed-field gel electrophoresis, (3) ribotyping, (4) polymerase chain reaction (using either random primers or repetitive DNA sequence primers), and (5) polymerase chain reaction-restriction fragment length polymorphism analysis of e.g. the urease genes. Furthermore, reproducibility, discriminatory power, ease of performance and interpretation, cost and toxic procedures of each method are assessed. To date no direct comparison of all the molecular typing methods described has been performed in the same study with the same H. pylori strains. However, PCR analysis of the urease gene directly on suspensions of H. pylori or gastric biopsy material seems to be useful for routine use and applicable in specific epidemiological situations.

Antimicrobial susceptibility testing of 230 Helicobacter pylori strains: importance of medium, inoculum, and incubation time

No standardized method of susceptibility testing for Helicobacter pylori is currently available, so before a large agar dilution study comprising 230 H. pylori strains belonging to more than 80 genetically different groups was initiated, we performed a relatively small preliminary study to determine the influences of medium, inoculum density, and incubation time. Seven media were investigated and were primarily evaluated on the basis of their abilities to support growth both semiquantitatively and qualitatively; Iso-Sensitest agar supplemented with 10% horse blood was found to be well suited for the purpose; this was closely followed by Mueller-Hinton agar with 10% horse blood, Mueller-Hinton with 10% sheep blood, and finally, 7% lysed horse blood agar. Investigations of two inoculum densities and two incubation times resulted in recommendations for the use of 10(9) CFU/ml (10[6] CFU/spot) as the inoculum and 72 h as the incubation time. A modest inoculum effect was noted for amoxicillin and metronidazole. By the methodology derived from our preliminary study, the susceptibilities of 230 H. pylori strains to six antibiotics were subsequently determined. The results were generally in accord with those of others, and apart from metronidazole, the MIC of which for approximately 25% of the strains tested was >8 microg/ml, resistance was low in Denmark. The situation might, however, quickly change when and if the number of indications for antibiotic therapy for H. pylori infections increase. Consequently, susceptibility testing of all H. pylori strains is recommended in order to survey the development of resistance, and in our hands the described methodology was relatively easy to perform and the results were easy to read.

The antibacterial activity of a siderophore. 3. The activity of deferoxamine in vitro and its influence on the effect of antibiotics against Escherichia coli, Proteus mirabilis and coagulase-negative staphylococci

The in vitro activity of deferoxamine (DFO) both per se and in combination with the reductant ascorbic acid (AA) was determined against 10 E. coli strains, 5 P. mirabilis strains, and 10 coagulase-negative staphylococci. In terms of interaction, the influence of DFO on the activities of cephalothin and gentamicin was furthermore investigated against the same panel of strains employing a macrobroth dilution technique and killing-curve kinetics. The MICs of cephalothin and gentamicin were lowered for one half of the strains. Moreover, DFO prolonged the generation times of logarithmic growth phase considerably, especially when the reductant AA was present. The interactions between DFO or DFO+AA and subinhibitory concentrations of antibiotics were established by the application of growth constants, and resulted in synergy for 15 out of 25 strains with cephalothin and 9 out of 25 strains with gentamicin.

Changing patterns among the subgroups of strains of Staphylococcus aureus of phage group II in Danish hospitals from 1961-91

During the period 1961-91 a total of 567,635 strains of Staphylococcus aureus from hospitalized patients in Denmark have been characterized according to their antibiotic resistance, site of isolation and phage type. Strains of phage group II (typed by the phages 3A, 3C, 55 and 71) have been analysed further. The occurrence of group II strains was relatively constant (approximately 16%) from 1961 until 1983. Since then the frequency of group II strains increased; in 1991 they accounted for 22.7% of all S. aureus strains isolated. Strains of group II can, on the basis of their phage types, be divided in four subgroups: 3A, 71, 71+ and the 'rest of group II'. Furthermore, within these groups strains may differ from one another in respect to their sensitivity to phages. The increased isolation of group II strains during recent years was because of an increase in strains of subgroups 71+ and the 'rest of group II strains'. In 1991 these two subgroups accounted for 89.7% of all group II strains. Furthermore, an increasing number of group II strains, 71.4% in 1991, was typable only at RTD x 100. The increase in the number of group II strains was even throughout Denmark. All four subgroups of group II have, during the observation period, become more frequently resistant to penicillin and/or tetracycline. Strains typed at 100 x RTD of subgroup 71+ and the 'rest of group II' are more frequently antibiotic resistant than the rest of the group II strains. Strains of the increasing subgroups occurred most often in abscesses.

The antibacterial activity of a siderophore. 2. The influence of deferoxamine alone and combined with ascorbic acid on the activity of antibiotics against Staphylococcus aureus

The in vitro activity of deferoxamine (DFO) combined with cephalothin, gentamicin, cefotaxime, vancomycin, and fusidic acid, in the presence or absence of the reductant ascorbic acid (AA) was investigated against Staphylococcus aureus by a macrobroth dilution technique and killing curve kinetics. DFO and in particular DFO + AA lowered the MICs of cephalothin, gentamicin, cefotaxime, and fusidic acid for most of the strains and in some instances also the MICs of vancomycin. To characterize the interaction between DFO or DFO + AA and antimicrobials we applied the growth constants of logarithmic growth phase. Generally DFO acted synergistically with cephalothin, gentamicin, vancomycin, and fusidic acid, particularly in the presence of AA, and in some cases synergy was demonstrated with cefotaxime, too.

Dicloxacillin concentrations in amputation

We treated 18 patients undergoing major lower limb amputation due to ischemia by intravenous administration of 1 g dicloxacillin either 0, 3, or 6 hours before surgery followed by a similar dose 8 hours after the first dose. The administration immediately before the operation resulted in the highest peroperative antibiotic concentrations in the muscular and subcutaneous tissue at the amputation level, exceeding the MIC value of Staphylococcus aureus. Similarly, the concentrations in drain fluid were highest in these patients. The median drain secretion later than 12 hours after surgery amounted to only 5 mL, and at that time the concentration of dicloxacillin was less than the MIC of Staphylococcus aureus in all the samples.

In vitro activity of vancomycin against enterococci

The in vitro activity of vancomycin against 40 clinical isolates of enterococci was determined by a macro-tube dilution method and by quantitative killing curve procedures employing the standard medium of our department, i.e. a filtered ox broth. An attempt to remove the influence of technical factors on the MBC determination was made by using an inoculum in the early logarithmic growth phase and ensuring the exposure of all the organisms to the antibiotic. Vancomycin showed a good inhibitory activity for the enterococci tested (MIC90 of 1.6 micrograms/ml, 3.1 micrograms/ml and 1.6 micrograms/ml for S. faecalis, S. faecium and S. durans, respectively), but no bactericidal effect could be demonstrated as measured by the MBCs (greater than 100 micrograms/ml) and killing curve procedures.

The antibacterial activity of a siderophore. 1. In vitro activity of deferoxamine alone and in combination with ascorbic acid on Staphylococcus aureus

The in vitro antimicrobial activity of the siderophore, deferoxamine, alone and in combination with ascorbic acid, was investigated against 10 clinical isolates of S. aureus employing the broth dilution test and the time-kill method. By the broth dilution test neither activity of deferoxamine and ascorbic acid was demonstrated. In the time-kill study the combination of deferoxamine and ascorbic acid showed a growth inhibiting effect of 3-6 log units at 6 hours. The growth inhibition demonstrated at 6 hours was overcome at 24 hours but could either partially or completely be maintained when repeated addition of the combination of deferoxamine and ascorbic acid or ascorbic acid alone was performed. The antimicrobial effect of deferoxamine could be abolished by adding ferric citrate in ample amounts to saturate deferoxamine with iron.

In vitro antibacterial activities of eleven antibiotics against S. faecalis

The in vitro antibacterial activities of penicillin, ampicillin, piperacillin, azlocillin, vancomycin, erythromycin, clindamycin, gentamicin, streptomycin, cefotaxime, and ceftriaxone against 198 S. faecalis strains were investigated, employing an agar dilution technique. Results were generally in accord with those of other studies. Ampicillin and penicillin showed equal activities. Twenty percent of the strains were resistant to erythromycin, which correlated with resistance to clindamycin. The activity of cefotaxime was fairly good, but the clinical importance of this observation warrants further investigation. Twenty percent showed high-level resistance to streptomycin. High-grade resistance to gentamicin was noted for one isolate only, making gentamicin the first-choice aminoglycoside for combination treatment at present.

In vitro susceptibility of diarrhoea producing gram negative enteric bacteria to sulfasalazine, 5-aminosalicylic acid, sulfapyridine and four quinolones. Brief report

The in vitro susceptibility of diarrhoea producing Gram negative enteric bacteria to sulfasalazine, 5-aminosalicylic acid, sulfapyridine and four quinolones was investigated using an agar dilution method. All strains were resistant to 1600 micrograms/ml of sulfasalazine and 5-aminosalicylic acid. MIC range of sulfapyridine for Y. enterocolitica was 3.1-25 micrograms/ml (median:6.2) and for Salmonella 25-100 micrograms/ml (median: 100) Campylobacter jejuni/coli were less susceptible to sulfapyridine with MIC values ranging from 200 to 800 micrograms/ml. Shigella and three of five E. coli strains were resistant to 1600 micrograms/ml of sulfapyridine. Two strains of E. coli were inhibited by 25 micrograms/ml. All strains were fairly susceptible to enoxacin, ciprofloxacin, pefloxacin and ofloxacin. Cirpofloxacin was the most active drug on weight basis.

Influence of carbon-dioxide tension and medium buffer concentration on medium pH and MIC values of erythromycin for Escherichia coli ATCC 25922 and Staphylococcus aureus ATCC 25923 in a micro-aerobic atmosphere

The effect of an elevated carbon-dioxide tension on medium pH and MIC determination with erythromycin for Staphylococcus aureus (ATCC 25923) and Escherichia coli (ATCC 25922) was investigated in a micro-aerobic atmosphere, using an agar dilution method. During 30 h of incubation in an atmosphere containing approximately 6% CO2, 5% O2 and 89% N2, pH of uninoculated, as well as of seeded, blood agar plates decreased from 7.4 to 6.8. MIC values of erythromycin were two dilution steps higher after micro-aerobic incubation than after aerobic incubation. A decrease in agar pH during micro-aerobic incubation was eliminated by increasing the phosphate buffer concentration in the medium. However, MIC values of erythromycin remained high.

Thomsen-Friedenreich-related antigen in non-neoplastic ureter urothelium and transitional cell tumours of the urinary bladder. An immunohistochemical study employing the monoclonal antibody 49H.8

This study, which is part of a larger immunohistochemical investigation of blood-group antigens in non-neoplastic urothelium and bladder cancer, reports our findings on the expression of an antigen related to the cryptic Thomsen-Friedenreich antigen (beta Gal 1-3 GalNAc) of erythrocytes. De-waxed sections of 19 ureters and of 93 transitional cell tumours, either untreated or pretreated with neuraminidase, were subjected to an indirect immunoperoxidase staining, employing the monoclonal antibody 49H.8. Staining results were compared to Lewis-secretor types, morphology, and in tumours to the clinical course as regards recurrence rate and the development of either stroma invasive recurrence or papillomatosis as well. Ureters not subjected to neuraminidase were unstained, whereas urothelium in 12 of 19 ureters subjected to neuraminidase showed staining. Serial dilution of antibody disclosed quantitative differences related to the Lewis-secretor types. Lea+b- urothelium, i.e., non-secretor urothelium, had the highest end-point titers. Endothelium was unstained. Thirty-six of the 93 tumours showed staining without prior neuraminidase treatment, 31 showed staining after neuraminidase treatment only, while 26 were unstained. Staining correlated with the pathological stage and grade (p less than 0.05), but not with the clinical course (p greater than 0.05). The results do not support previous observations on the prognostic value of Thomsen-Friedenreich antigen determination in superficial bladder cancer.

Lewis a antigen in transitional cell tumors of the urinary bladder

The failure of A,B,H antigens as prognostic parameters in noninvasive bladder cancer of blood group O individuals, who constitute 44% of the population, encouraged the evaluation of the closely related Lewis a antigen. Ninety-three tumors of the urinary bladder were stained employing the Tween 20 (Merck)-modified immunoperoxidase staining technique and serial dilution of monoclonal anti-Lewis a antibodies. On the basis of recent findings in non-neoplastic ureter urothelium of erythrocyte Lea+b-, Lea-b+, and Lea-b- individuals, alterations in tumors, except eight from Lea-b- individuals, were quantified on a scale from 0 (normal) to 3 (total loss). Scores were related to the pathologic stage and grade (P less than 0.01), and, in stage Pa tumors, to the clinical course: recurrence rate (P less than 0.10), stroma invasive recurrence, and/or papillomatosis (P less than 0.05). Although further studies are needed the current study points to Lewis a antigen determination as an advantageous prognostic tool in stage Pa tumors of the urinary bladder of Lea-b+ and Lea+b- individuals, who, together, constitute 94% of the population.

Relationship between penicillinase production and the in-vitro activity of methicillin, oxacillin, cloxacillin, dicloxacillin, flucloxacillin, and cephalothin against strains of Staphylococcus aureus of different phage patterns and penicillinase activity

A total of 157 strains of Staphylococcus aureus of different phage patterns and penicillinase production were investigated for their susceptibility to methicillin, oxacillin, cloxacillin, dicloxacillin, flucloxacillin and cephalothin by an agar dilution method. Only strains of the 52, 52A, 80, 81 complex had significantly higher IC-50 values than the rest of the strains. No correlation was found between penicillinase production and the IC-50 values. Penicillinase susceptibility divided the antibiotics into two groups: one including methicillin, oxacillin and cephalothin, and the other included dicloxacillin, cloxacillin and flucloxacillin. Nineteen strains of S. aureus which existed in both a penicillinase producing and a penicillinase non-producing form were examined for susceptibility to the six antibiotics. The difference between penicillinase positive and penicillinase negative variants was especially marked for flucloxacillin and cephalothin. Methicillin induction prior to susceptibility testing had only a minor influence on the results. Investigation of the stability of methicillin and the four isoxazolyl penicillins against penicillinase production by 37 strains of S. aureus showed methicillin to be the most stable antibiotic. This was followed by dicloxacillin, cloxacillin, flucloxacillin, and oxacillin in that order. The order of stability was identical and independent of phage pattern and quantitative penicillinase production.

A, B, H antigen expression in transitional cell carcinomas of the urinary bladder

The prognostic value of A, B, H blood group antigen determination in superficial bladder cancer is unclear. Recent immunohistochemical studies employing monoclonal antibodies and Ulex Europaeus Agglutinin I (UEA-I) (Vector) have shown that A, B, H detectability and distribution in non-neoplastic urothelium are influenced by methodologic factors and, most importantly, by the secretor status. The authors investigated the A, B, H antigen in 93 tumors of the urinary bladder (78 secretors, 15 nonsecretors) and semiquantified the alterations from the expected normal expression on a scale from 0 to 3. Four O saliva nonsecretors as expected showed no staining and were excluded. Eighty tumors showed abnormal A, B, H expression and in 37 of these, A, B, H antigens were not detected. Tumors of A and O individuals showed statistically different reactivities, probably related to differences in the specificity of the employed A- and H-reagents. A, B, H expression was influenced by stage and grade (P less than 0.05, P less than 0.10) and was correlated to the clinical course of A but not O patients. These results, suggesting that alterations in the A, B, H expression occur early in the neoplastic development and follow the synthetic pathways in an opposite direction, emphasize that reagents recognizing blood group precursor substances, common to all individuals irrespective of the ABO and saliva secretor types, may increase the prognostic accuracy of blood group antigen determination in bladder cancer.

Value of clinical decision on antibiotic treatment of fever episodes following transurethral resection of the prostate

The value of clinical decision on antibiotic treatment of fever episodes following transurethral resection of the prostate was assessed in 134 patients. Besides bacteriuria, need of blood transfusions and various catheter problems were associated with a significant number of fever episodes. The majority of patients with fever not given antibiotic therapy had negative urine cultures (90%), whereas 41% of the patients with fever treated with antibiotics showed negative urine cultures indicating an overtreatment of these patients. Out of the total number of patients, only 10% with subsequent negative urine cultures received antibiotics, a figure which should be compared to the inevitable rate of overtreatment when general antibiotic prophylaxis is preferred.

The determination of specific IgA-antibodies to Yersinia enterocolitica and their role in enteric infections and their complications

Specific serum IgA-antibodies, mainly produced in the lymphoid tissue of the gastrointestinal tract (GALT) might exhibit some special characteristics deviating from IgM- and IgG-antibodies: they do not agglutinate nor fix complement. They cannot be determined by usual routine antibody techniques; indirect methods must be used. An antiglobulin-assay was used in an extensive investigation over a two-year period on sera from 8,445 patients to determine IgA-antibodies specific to Yersinia enterocolitica, serotype 3. Y. enterocolitica agglutinins were found in 965 patients, 508 of them with significant titres of greater than or equal to 80. 347 of the 2,111 patients with low titres (10 to 40) had a significantly elevated amount of IgA antibodies. The diagnoses of the IgA-positive patients fell into three groups: acute infections, acute reactive complicatory inflammations, mainly arthritis, chronic inflammatory connective tissue diseases. The IgA-antibody pattern was: In early samples from patients with acute enteric infections they might be the only antibodies present following, largely, during the course of the disease the agglutinating IgM and IgG antibodies, except in patients with long-lasting or chronic complications where IgA antibodies were elevated. It is concluded that determination of specific antibodies of IgA class in cases of Y. enterocolitica infections is an important diagnostic test and, moreover, of prognostic value in the evaluation of chronicity.

In-vitro activity of methicillin against clinical isolates of Staphylococcus aureus

Methicillin activity against 149 penicillin-resistant, methicillin-susceptible Staphylococcus aureus strains from bacteraemia cases with endocarditis (n = 89) or without endocarditis (n = 60), from the years 1976-1981, was studied with broth dilution and agar dilution. While no differences in methicillin susceptibility were found in relation to the origin of the strains, Staph. aureus of the phage type complex 94,96 showed significantly higher MIC and IC50 by agar dilution than strains of other phage groups/complexes. This difference probably has no clinical importance but is of epidemiological interest. Broth dilution MIC was generally one dilution higher than agar dilution MIC, possibly explained by methodological factors. The MBC/MIC ratios never exceeded two in any of the strains, indicating a lack of tolerance in these clinically important isolates.