Statins influence epithelial expression of the anti-microbial peptide LL-37/hCAP-18 independently of the mevalonate pathway.

Anti-microbial resistance increases among bacterial pathogens and new therapeutic avenues needs to be explored. Boosting innate immune mechanisms could be one attractive alternative in the defence against infectious diseases. The cholesterol-lowering drugs, statins, have been demonstrated to also affect the immune system. Here we investigate the effect of statins on the expression of the human cathelicidin anti-microbial peptide (CAMP) LL-37/hCAP-18 [encoded by the CAMP gene] and explore the underlying mechanisms in four epithelial cell lines of different origin. Simvastatin induced CAMP expression in bladder epithelial cells telomerase-immortalized uroepithelial cells (TERT-NHUCs), intestinal cells HT-29 and keratinocytes HEKa, but not in airway epithelial cells A549. Gene induction in HEKa cells was reversible by mevalonate, while this effect was independent of the cholesterol biosynthesis pathway in TERT-NHUCs. Instead, inhibition of histone deacetylases by simvastatin seems to be involved. For HT-29 cells, both mechanisms may contribute. In addition, simvastatin increased transcription of the vitamin D-activating enzyme CYP27B1 which, in turn, may activate LL-37/hCAP-18 production. Taken together, simvastatin is able to promote the expression of LL-37/hCAP-18, but cell line-specific differences in efficacy and the involved signalling pathways exist.

Association between vitamin D, antimicrobial peptides and urinary tract infection in infants and young children.

AIM: Vitamin D stimulates production of the endogenous antimicrobial peptides cathelicidin and ß-defensin-2, which are expressed in the urinary tract. We investigated vitamin D status and levels of cathelicidin and ß-defensin-2 and their association with urinary tract infection (UTI). METHODS: The study included 120 children under three years of age: 76 children with UTIs and 44 otherwise healthy children with congenital hydronephrosis. Serum 25-hydroxycholecalciferol levels were measured by direct competitive electro-chemiluminescence immunoassay, and plasma cathelicidin and ß-defensin-2 concentrations were analysed by enzyme-linked immunosorbent assay. RESULTS: We found that vitamin D insufficiency and deficiency are prevalent in young children (21%). Serum vitamin D levels negatively correlated with age and were significantly lower in girls. Levels of vitamin D positively correlated with levels of cathelicidin but not with ß-defensin-2. Low concentrations of vitamin D were associated with UTIs in girls, but we did not see any correlation with the recurrence of infection at one-year follow-up. CONCLUSION: Vitamin D deficiency is common and may prove to be a risk factor for UTIs especially in girls. We hypothesise that adequate supplementation with vitamin D may become a way to prevent first-time UTIs.

Markers of innate immune activity in patients with type 1 and type 2 diabetes mellitus and the effect of the anti-oxidant coenzyme Q10 on inflammatory activity.

Major long-term complications in patients with diabetes are related to oxidative stress, caused by the hyperglycaemia characteristic for diabetes mellitus. The anti-oxidant coenzyme Q10 (CoQ10) has therefore been proposed as a beneficial supplement to diabetes treatment. Apart from its anti-oxidative function, CoQ10 appears to modulate immune functions by largely unknown mechanisms. The aim of this study was therefore to investigate the effect of CoQ10 on antimicrobial peptides and natural killer (NK) cells, both innate immune components implicated in the pathogenesis of diabetes and diabetes-associated long-term complications such as cardiovascular disease. We determined serum levels of antimicrobial peptides and the phenotype of NK cells isolated from peripheral blood of patients with type 1 (T1DM) or type 2 diabetes mellitus (T2DM) and from healthy controls. In addition, the same parameters were determined in diabetic patients after a 12-week period of CoQ10 supplementation. Two antimicrobial peptides, the human cathelicidin antimicrobial peptide (CAMP) and the human beta defensin 1 (hBD1), were reduced in serum from patients with T1DM. This defect was not reversible by CoQ10 supplementation. In contrast, CoQ10 reduced the levels of circulating hBD2 in these patients and induced changes in subset distribution and activation markers in peripheral NK cells. The results of the present study open up novel approaches in the prevention of long-term complications associated to T1DM, although further investigations are needed.

Characterisation of uropathogenic Escherichia coli from children with urinary tract infection in different countries.

Uropathogenic Escherichia coli (UPEC) carry many virulence factors, including those involved in long-term survival in the urinary tract. However, their prevalence and role among UPEC causing urinary tract infection (UTI) in children is not well studied. To further understand the virulence characteristics of these bacteria, we investigated the prevalence of antibiotic resistance, antigen 43 genes, curli and cellulose among UPEC in children from different countries. Isolates (n = 337) from five countries were tested for antibiotic susceptibility, phylogenetic groups, prevalence of flu, fluA(CFT073), fluB(CFT073), curli and cellulose. High prevalence of multidrug resistance and extended spectrum beta lactamase production was found among Iranian and Vietnamese isolates. Resistance was associated with phylogenetic group D while group B2 was associated with fluA(CFT073) and fluB(CFT073). Fewer Iranian isolates carried fluA(CFT073), curli and cellulose. fluB(CFT073) was most prevalent among Slovak isolates. Ampicillin and amoxicillin/clavulanic acid resistance was prevalent among fluA(CFT073)- and fluB(CFT073)-positive Australian, Iranian and Swedish isolates. Lack of curli and cellulose was associated with resistance among Vietnamese isolates. We conclude that major differences exist in the prevalence of antibiotic resistance among UPEC from different countries. Associations observed between resistance and virulence factors may, in different ways, promote the long-term survival of UPEC in the urinary tract.

Cellulose and PapG are important for Escherichia coli causing recurrent urinary tract infection in women.

PURPOSE: To identify Escherichia coli factors associated with bacterial persistence in the human urogenital tract using well-defined clinical isolates from women with cystitis. METHODS: E. coli were isolated from women suffering from recurrent cystitis. For comparison, isolates from sporadically infected patients and healthy volunteers were included in the analysis. Samples were taken on three occasions from the urine, periurethra, and vagina. Isolates were typed by pulsed-field gel electrophoresis, and virulence factors were detected by PCR and morphotypic analysis. RESULTS: In all patients, the original E. coli strain was isolated repeatedly and from different regions. The presence of papG coding for a P fimbriae subtype linked to pyelonephritis was associated with strains isolated from patients with recurrent cystitis, including both among urinary and vaginal isolates. The biofilm component cellulose was detected at a higher frequency in urinary isolates from recurrent versus sporadic cystitis. CONCLUSION: The hypothesis of a periurethral/vaginal E. coli reservoir is supported by the results of this study. Our results also indicate an impact of cellulose on E. coli persistence in the human urogenital tract.

Serotyping of Proteus mirabilis clinical strains based on lipopolysaccharide O-polysaccharide and core oligosaccharide structures.

The aim of this work was to serotype Proteus mirabilis urinary tract infection (UTI) strains based on chemically defined O-antigens with the use of two clinical collections from Sweden and Poland consisting of 99 and 24 UTI strains, respectively. A simple two-step serotyping scheme was proposed using enzyme immunoassay with heat-stable surface antigens of Proteus cells and immunoblotting with isolated lipopolysaccharides (LPSs). Using polyclonal anti-P. mirabilis rabbit antisera, 50 Swedish and 8 Polish strains were classified into serogroups O10, O38, O36, O30, O17, O23, O9, O40, O49, O27, O5, O13, O24, O14, and O33. From the Swedish strains, 10 belonged to serogroup O10 and five to each of serogroups O38, O36, and O9. Therefore, none of the O-serogroups was predominant. The majority of the serotyped clinical strains possess acidic O-antigens containing uronic acids and various acidic non-carbohydrate substituents. In immunoblotting, antisera cross-reacted with both O-antigen and core of LPSs. The core region of 19 LPSs bound a single serum, and that of 12 LPSs bound more than two sera. Following bioinformatic analysis of the available sequences, a molecular approach to the prediction of Proteus core oligosaccharide structures was proposed. The identification of the core type of P. mirabilis R110, derived from a serogroup O3 wild strain, using restriction fragments length polymorphism analysis of galacturonic acid transferase is shown as an example. In summary, the most frequent O-serogroups among P. mirabilis UTI stains were identified. The diversity of serological reactions of LPSs is useful for serotyping of P. mirabilis clinical isolates. A possible role of the acidic components of O-antigens in UTI is discussed.

Genetic relatedness and virulence gene profiles of Escherichia coli strains isolated from septicaemic and uroseptic patients.

We investigated the relationship between clonality and virulence factors (VFs) of a collection of Escherichia coli strains isolated from septicaemic and uroseptic patients with respect to their origin of translocation. Forty septicaemic and 30 uroseptic strains of E. coli were tested for their phylogenetic groupings, genetic relatedness using randomly amplified polymorphic DNA (RAPD), biochemical fingerprinting method (biochemical phenotypes [BPTs]), adherence to HT-29 cells and the presence of 56 E. coli VF genes. Strains belonging to phylogenetic groups B2 and D constituted 93% of all strains. Fifty-four (77%) strains belonged to two major BPT/RAPD clusters (A and B), with cluster A carrying significantly (P = 0.0099) more uroseptic strains. The degree of adhesion to HT-29 cells of uroseptic strains was significantly (P = 0.0012) greater than that of septicaemic strains. Of the 56 VF genes tested, pap genes was the only group that were found significantly (P < 0.0001) more often among uroseptic isolates. Phylogenetic group B2 contained a significantly higher number of strains carrying pap genes than those in group D. We conclude that uroseptic E. coli are clonally different from septicaemic strains, carry more pap genes and predominantly adhere more to the HT-29 cell model of the gut.

Making medical devices safer: impact of plastic and silicone oil on microbial biofilm formation.

BACKGROUND: Medical devices face the challenge of microbial biofilm attached to the surface. Ultimately, this may jeopardize the function of the device and increase the patient's risk of infection. However, reliable methods to prevent biofilm are lacking. AIM: To investigate the effect of silicone oil-coated polypropylene plastic, used in a new automatic urinometer, on biofilm formation; furthermore, to explore the impact of silicone oil viscosity and compare polypropylene with polystyrene, another common medical plastic. METHODS: Common pathogens, including extended-spectrum beta lactamase (ESBL) -producing and multi-drug-resistant bacteria, as well as Candida albicans, were investigated. Isogenic Escherichia coli strains deficient in the important biofilm forming factors curli, cellulose and type 1 fimbriae (fim D) were used to determine the possible mode of action by silicone oil. Clear flat-bottomed polypropylene or polystyrene wells were pretreated with either low- or medium-viscosity silicone oil and microbes were added. After 72 h, biofilm formation was quantified using crystal violet assay. FINDINGS: Silicone oil-coated polypropylene plastic surfaces, regardless of the oil viscosity, significantly inhibited biofilm formation of all tested Gram-negative and Gram-positive bacteria, including ESBL-producing and multi-drug resistant strains, as well as C. albicans. Silicone oil did not affect bacterial or candida growth and curli fimbriae were found to be the main target of silicone oil. Polypropylene plastic itself without oil had a better effect in preventing biofilm formation than polystyrene. CONCLUSION: These findings suggest a new strategy to decrease microbial biofilm formation, which may reduce hospital-acquired infections and prevent dysfunction of medical devices.

Host species-specific translocation of Escherichia coli.

The purpose of this paper is to investigate the rate of translocation of Escherichia coli strains in different experimental/animal models. Four proficient translocating E. coli strains isolated from mesenteric lymph nodes (MLNs) and/or the blood of rats (strains KIC-1 and KIC-2), from a fatal case of pancreatitis (HMLN-1) and from pigs (PC-1 isolated in this study) were tested for their ability to translocate across two host species and the Caco-2 cell line as a model of the human gut epithelium. HMLN-1 was found in the MLNs of all 15 pigs tested. This strain, however, did not translocate in any rats and only colonised the caecum of four rats in small numbers. HMLN-1 and PC-1 were the dominant translocating strains in Caco-2 cells compared to KIC-1 and KIC-2, which were found to translocate at a lower rate in pigs and in Caco-2 cells. The rate of translocation of PC-1 in rats was also very low compared to KIC-1 and KIC-2. We suggest that, in studies aiming to investigate the mechanism of translocation of E. coli strains isolated from humans, rats may not be an appropriate animal model and that the Caco-2 cells or pigs are more suitable in vitro and in vivo models, respectively.

Virulence characteristics of Escherichia coli strains causing acute cystitis in young adults in Iran.

BACKGROUND: Escherichia coli strains that cause cystitis posses virulence properties that facilitate their colonisation and persistence in the bladder. In Iran, despite the high number of the urinary tract infections, very few studies has been done to determine the role of these virulence properties in the pathogenesis of E. coli cyctitis. PATIENTS AND METHODS: Eighty-seven strains of E. coli, isolated from young adults with cystitis in Shiraz, Iran, were examined for the expression of type 1 and P-fimbriae, mannose resistant haemagglutination, haemolysin production, aerobactin-mediated iron uptake, O:K serotypes, biochemical phenotypes (BPTs) and their antibiotic susceptibility patterns. RESULTS: Seventy-six percent of the strains expressed multiple virulence properties. There was a significant correlation between the presence of aerobactin and the expression of type 1 fimbriae. All P-fimbriated strains produced aerobactin with 50% of them also coexpressing haemolysin. Of the 29 different O:K serotypes identified, 42% belonged to serotypes not commonly found among European serotypes associated with UTI. Strains of O groups 4 and 6 expressed more virulence factors than the others. A high resistance against ampicillin, trimethoprim and cotrimoxasol was observed among the isolates with 53% of the isolates showing multiresistance to these three antibiotics. Certain BPTs were also found among O:K serotypes with some containing strains of the same virulence profile. CONCLUSION: We conclude that certain colonal groups of E. coli are commonly associated with cystitis in young adults in Iran with strains possessing a combination of aerobactin and type 1 fimbriae being the dominant ones and belonging to serotypes not commonly found in Europe. We also conclude that the multiple antibiotic resistant E. coli strains causing cyctitis are highly prevalent in this part of the country.

The impact of vitamin D on the innate immune response to uropathogenic Escherichia coli during pregnancy.

Urinary tract infections are highly common during pregnancy, and can cause serious complications for the mother and baby. Vitamin D, predominantly obtained from the sunlight, is known to have an effect on the urothelium, with immunomodulatory capacity against Escherichia coli infection. However, its influence at this site remains to be further explored. This study therefore investigated its impact during pregnancy in a population of women who have the possibility of adequate year-round sun exposure. Serum from pregnant Ugandan women (n = 32) in each trimester of pregnancy, from women after delivery (n = 29) and from never-pregnant controls (n = 25) was collected. 25-Hydroxyvitamin D (25-OHD), cathelicidin LL-37, human ß-defensin 2, interleukin (IL)-8 and soluble CD14 serum concentrations were measured by chemiluminescence immunoassay or ELISA. The ability of serum to inhibit E. coli growth was tested. The immunomodulatory capacities of these serum samples and 1,25-dihydroxyvitamin D3 were investigated in urothelial cells. Increases in 25-OHD and LL-37 levels were observed as pregnancy progressed, peaking in the third trimester. Serum 25-OHD levels were higher in multigravidae than in primigravidae, and correlated positively with maternal age. IL-8 levels were lower in the third trimester than in the first trimester, increased after delivery, but remained below those of never-pregnant women. Similarly, soluble CD14 concentrations increased after delivery. As gestation advanced, serum had an increased capacity to inhibit E. coli growth. In vitro, it modulated the IL-8 response to infection in a vitamin D concentration-dependent manner. Our findings demonstrate that increasing vitamin D levels as pregnancy advances modulate the innate immune system towards a protective response to infection.

Test-retest reliability of the nasopharyngeal culture in children.

Aspects of test-retest reliability of the nasopharyngeal culture were evaluated in children with otitis media and in ear, nose and throat (ENT)-healthy children, in all 174 cases. The nasopharyngeal colonization of Streptococcus pneumoniae, Haemophilus influenzae, Branhamella catarrhalis and beta-haemolytic streptococci was determined for a group of children with well-defined otitis media effusion (OME). The valitity of the results was then tested in a new group of children with OME. Despite seasonal differences and different bacteriologists analysing the specimens, high conformity was found between the two groups regarding distribution and recovery rates of the potential pathogens studied. The test-retest reliability of the culture was also analysed by duplicate specimens in children with acute otitis media (AOM), OME and in ENT-healthy children. The reproducibility of the findings of pathogens, whether quantitative aspects were considered or not, was found to be between 70 and 80% for children with AOM and OME.

Nasopharyngeal culture with quantitative analysis of pathogenes in chronic otitis media with effusion. Effects on pathogen yield of different swabs and transport methods.

The influence of different swabs and transport media on nasopharyngeal culture pathogen recovery has been studied in patients with chronic otitis media with effusion. Transport times of less than two hours have been used. Protecting the cotton wire swab with a polyethylene shealth to prevent contamination by nasal flora did not have any significant influence either on the recovery of potential pathogens or on the contaminating nasal flora. Facilitating a quantitative analysis of the nasopharyngeal culture by transporting the specimen in empty tubes gave a pathogen recovery rate similar to that with transport in Stuart medium, whereas an attempt at transporting in sodium chloride or prereduced PY broth led to significantly lower yields of Branhamella catarrhalis (p less than 0.01) and in PY broth on Haemophilus influenzae as well (p less than 0.01).

Characterization of Escherichia coli isolated in blood, urine and faeces from bacteraemic patients and possible spread of infection.

Blood, faecal and urine isolates from patients with culture-verified E. coli bacteraemia were investigated with respect to biochemical phenotype, O and K serotype and P. fimbriae. In 10/16 bacteraemic episodes, the blood isolates were identical to the corresponding faecal strains. In four of the remaining infections, antimicrobial therapy was initiated more than two days before faecal samples were taken. Urine cultures revealed growth of E. coli in 12/16 samples. However, only three had clinical signs of symptomatic urinary tract infections. Eight of these E. coli were saved. Further analysis revealed that five of eight strains were identical to the corresponding isolates from blood and stool samples, two were only identical to the faecal strain, while one was different to the corresponding E. coli in the blood and stool samples. The isolated E. coli strains belonged to varying and, among previously healthy persons, normally less common serotypes. No epidemiological relationship was observed between the studied strains. The high incidence of identical strains in the blood, stool and urine indicates a bacterial spread from the faecal flora directly to the urine and possibly also, via the blood, to the urine.

Serum resistance in Escherichia coli strains causing acute pyelonephritis and bacteraemia.

The capacity of Escherichia coli to resist the bactericidal action of serum was examined in 367 clinical isolates obtained from children with acute pyelonephritis (n = 57), adults with acute pyelonephritis (n = 55), non-diabetic patients with bacteraemia (n = 101), diabetic patients with bacteraemia (n = 65) and from the faecal flora of healthy controls (n = 89). The incidence of serum-resistant E. coli strains was significantly higher in pyelonephritogenic strains from children and adults (93% and 82%) as compared to faecal control strains (57%, p less than 0.001 and p less than 0.005 respectively). Strains causing bacteraemia in non-diabetic and diabetic patients were more often serum resistant (72% and 80%) as compared to control strains (p less than 0.05 and p less than 0.001 respectively). The frequency of serum-sensitive strains was similar in diabetic patients with decreased renal function or proteinuria compared to those with normal renal function. There were no significant correlations between serum resistance of E. coli and expression of P fimbriae, type I fimbriae or mannose-resistant haemagglutination, cell surface hydrophobic properties, production of aerobactin, haemolysin or cytotoxic necrotizing factor in 53 pyelonephritogenic strains from adult patients.

Typing of coagulase-negative staphylococci from peritonitis in CAPD-patients by the PhP-CS system and REA.

Coagulase-negative staphylococci (CNS) were the most common bacteria causing peritonitis in patients treated with continuous ambulatory peritoneal dialysis (CAPD). In order to investigate if the same clone was responsible for the peritonitis in the different patients and if the exit site was the source of infection we followed 68 patients on CAPD for 2 years. During this period 9 patients had 12 episodes of peritonitis caused by CNS. Cultures were taken from exit site and peritoneal fluid in all patients at peritonitis and during the first study year at monthly intervals. In each culture up to 10 isolates of CNS were randomly collected and frozen. All 437 CNS isolates from the patients with CNS peritonitis were typed using a biochemical typing method and 41 isolates identical by this method were further discriminated by a DNA fingerprinting method. Identical strains were in no case isolated from different patients, indicating that no virulent strain was spread between the patients. The isolates causing the peritonitis were never found at the exist sites before the first day of the peritonitis in any patient. In only two patients was the same strain found at the exit site and in the peritoneal fluid on the first day of peritonitis. It thus seems that no virulent clone of CNS was infecting the patients and we found no evidence of CNS at the exit site causing the peritonitis.

Application of biochemical fingerprinting to the investigation of clonal groups of Salmonella of serotype Havana.

A computerised typing method based on biochemical fingerprinting was used to investigate biochemical phenotypes (BPTs) among 70 strains of Salmonella of serotype Havana isolated from human cases of gastroenteritis in Iran and other parts of the world. A total of 16 BPTs comprising five common and 11 single phenotypes was identified. The most frequently found BPT contained 24 isolates from Iran and nine from other countries. Three common BPTs with two, seven and 15 isolates were found among Iranian strains only and one common BPT with two isolates was found among non-Iranian strains only. Antibiotic-resistance patterns and virulence properties of strains from these common BPTs suggested that they might be unique clones. Forty-two Iranian isolates shared multi-resistance to between three and seven antibiotics. In contrast, none of the isolates from other countries was resistant to antibiotics. Furthermore, 43 Iranian isolates showed mannose-resistant adhesion to HeLa cells and 24 of them possessed an aerobactin-mediated iron-uptake system, whereas none of the isolates from other countries possessed any of these virulence properties. These findings suggest that four unique clones of Salmonella Havana with different BPTs and virulence properties are common in Iran; two particular clones were responsible for a majority of Havana infections there. However, the most prevalent BPT found among Iranian strains was also common in strains from other countries. It is concluded that biochemical fingerprinting, as used in this study, is a reliable method for identifying clonal groups of Havana strains. The method is reproducible, easy to perform and can be used alone, or in combination with other typing methods, in epidemiological studies of serotype Havana.

Host factors versus virulence-associated bacterial characteristics in neonatal and infantile bacteraemia and meningitis caused by Escherichia coli.

Possession of P fimbriae, virulence-associated O and K antigens, haemolysin and aerobactin production, and susceptibility to 10 antimicrobial agents were studied in 63 Escherichia coli strains isolated from blood or CSF of infants who were grouped according to their clinical characteristics. These isolates were compared with 35 faecal E. coli strains from healthy infants. Individual virulence factors showed a relatively weak association with invasive infection except for P fimbriae in urosepsis and aerobactin production in meningitis. Combinations of factors were generally more predictive for defining virulent clones, particularly in infants defined as being at normal risk of developing septicaemia. Thus, 62% of isolates from such infants had characteristics typical of previously described uropathogenic or meningitis-associated clones of E. coli, compared with 32% of the isolates from high-risk infants (i.e., those defined as being at high risk of developing septicaemia) and only 9% of the faecal isolates (p less than 0.001 and less than 0.05, respectively). Overall, 45% of the episodes of invasive infection were caused by such clones, whereas risk factors (conditions considered to be associated with increased risk of invasive infection) were present in 59% of the infected infants (39% in meningitis and urosepsis, 78% in cryptogenic septicaemia and untreated bacteraemia). The results indicated that bacterial factors played a significant causative role in neonatal meningitis and urosepsis, particularly in normal-risk infants, whereas predisposing host factors contributed greatly to cryptogenic septicaemia and untreated bacteraemia.

Soluble interleukin-1 receptor type II levels are elevated in cerebrospinal fluid in Alzheimer's disease patients.

Evidence from epidemiological, clinical and experimental studies favour the hypothesis that inflammatory events are part of the neuropathology in Alzheimer's disease. Proinflammatory cytokines such as interleukin-1 (IL-1), interleukin-6 (IL-6) and tumour necrosis factor-alpha (TNF-alpha) have been found in activated microglia in the vicinity of amyloid plaques in Alzheimer's disease brain. In the present study, the levels of soluble IL-1 receptor type II (sIL-1R type II), IL-1 receptor antagonist (IL-1ra), IL-1beta, IL-6 and TNF-alpha were analyzed in cerebrospinal fluid (CSF) samples from Alzheimer's disease patients and control subjects. The levels of sIL-1R type II were significantly higher in CSF from Alzheimer's disease patients than in CSF samples from control subjects (38.5+/-8 pg/ml (mean+/-S.E.M.) vs. 7.9+/-4 pg/ml, p<0.05). Measurements of the proinflammatory cytokines IL-6 and TNF-alpha showed no significant difference between the two groups, and the levels of IL-1beta and IL-1ra in the present material were too low to permit detection. The increased levels of sIL-1R type II may reflect a compensatory mechanism to balance an increased release of IL-1 receptor agonists in the Alzheimer's disease brain.

Non-radioactively labelled DNA probes for the detection of periodontopathogenic Prevotella and Porphyromonas species.

Digoxigenin-labelled synthetic DNA probes directed against the 16S rRNA were used for the direct detection of the periodontopathogenic bacteria Prevotella intermedia and Porphyromonas gingivalis in subgingival plaque by applying a DNA-RNA dot-blot hybridization procedure. The test was evaluated with 134 plaque samples from 26 patients with adult periodontitis or rapidly progressive periodontitis. The lower limit of detection was 10(4)-10(5) bacteria/specimen. A semiquantitative assessment of the two species in each sample and in the corresponding periodontal site was achieved by this technique. It is possible to examine 80-90 samples within two days with low material costs.