[Biomorphology of the Bacterial Invasion in Chronic pharyngotonsillitis ]. / Biomorphologie der Infektionsherde in rezidivierenden Mandelentzündungen.

BACKGROUND: The study investigates whether relapses of chronicpharyngotonsillitis result from new infections caused by theoro-pharyngeal microbial flora or are reactivations of persistent bacterial infections of the tonsils. METHODS: 90 patients, who were surgically treated for chronicpharyngotonsillitis (age 13 months to 38 years, at least 5 episodes of disease and antibiotic treatment in the past) were included. The surgery was performed in the antibiotic- and symptom-free period (at least 6 weeks after the last exacerbation). Sections of tonsillar tissue were investigated for invasive bacteria using fluorescence in situ hybridization (FISH) with group and species-specific 15/23S RNA based probes. RESULTS: Abundant foci of invasive bacteria were found in 86% of the resected tonsils, despite previous treatment with antibiotica and absent symptoms of ongoing infection. The diffuse infiltration of the tonsils was most predominant in the youger children. Local invasive processes such as abscesses, fissures filled with pus and superficial infiltration of the tonsillar epithelium were more typical for adults. All of the foci were polymicrobial and contained up to 10 different species or groups of bacteria. The local concentrations of invasive bacteria were up to 1012 bacteria/ml. CONCLUSIONS: The chronic pharyngotonsillitis is the result of persistent invasive bacterial infections. The polymicrobial nature of the infectious foci enables them to resist the antibiotic treatment and to exacerbate afterwards. The surgical treatment is unavoidable as long as antibiotic treatment fails to clear the infection.

Effectiveness of a hospital-wide selective screening programme for methicillin-resistant Staphylococcus aureus (MRSA) carriers at hospital admission to prevent hospital-acquired MRSA infections.

Screening of potential MRSA-positive patients at hospital admission is recommended in German and international guidelines. This policy has been shown to be effective in reducing the frequency of nosocomial MRSA transmissions in the event of an outbreak, but the influence of screening on reducing hospital-acquired MRSA infections in a hospital setting where MRSA is endemic is not yet well-documented. This study describes the effect of hospital-wide screening of defined risk groups in a 700-bed acute care hospital during a period of 19 months. In a cohort study with a 19-month control period, the frequencies of hospital-acquired MRSA infections were compared with and without screening. In the control period, there were 119 MRSA-positive patients, of whom 48 had a hospital-acquired MRSA infection. On the basis of this frequency, a predicted total of 73.2 hospital-acquired MRSA infections was calculated for the screening period, but only 52% of the expected number (38 hospital-acquired MRSA infections) were observed, i.e., 48% of the predicted number of hospital-acquired MRSA infections were prevented by the screening programme. The screening programme was performed with minimal effort and can therefore be recommended as an effective measure to help prevent hospital-acquired MRSA infections.

Cost analysis of a hospital-wide selective screening programme for methicillin-resistant Staphylococcus aureus (MRSA) carriers in the context of diagnosis related groups (DRG) payment.

The costs of a hospital-wide selective screening programme were analysed for a period of 19 months. During this time, 539 inpatients were screened, of whom 111 were MRSA-positive. Based on microbiological costs (staff and materials) and the costs of preventive contact isolation for 2 days until microbiological results were available (including material costs for medical consumable goods and the costs of additional nursing time), a total of 26,241.51 Euro was spent for the 539 patients screened. Based on cost units, the costs were 39.96 Euro for a patient found to be MRSA-negative and 82.33 Euro for a patient found to be MRSA-positive. Under the prospective diagnosis related groups (DRG) payment system in Germany, the costs of a prolonged hospital stay resulting from a hospital-acquired MRSA infection (HA-MRSA-I) are not reimbursed adequately by revenues, with a calculated average cost-revenue loss/patient with HA-MRSA-I of 5705.75 Euro. The screening programme was able to prevent 48% of predicted HA-MRSA-Is (35.2 patients with infection), thereby saving a predicted 200,782.73 Euro. After subtracting the screening costs, there was a net saving of 110,236.56 Euro annually. A sensitivity analysis of the break-even points for different screening frequencies and different MRSA incidence rates indicated that the screening programme became cost-effective at a low MRSA incidence rate, meaning that it can be recommended for most hospitals with an MRSA problem.

Bacterial biofilm within diseased pancreatic and biliary tracts.

BACKGROUND: Bacterial community structures in human pancreatic and biliary tracts were evaluated. METHODS: Gall bladder stones from 153 patients, 20 gall bladder walls, six common duct stones, 52 biliary stents, 21 duodenal biopsies, nine pancreatic duct biopsies, and five bile ducts were investigated using fluorescence in situ hybridisation (FISH) with ribosomal RNA targeted Cy3/Cy5 (carbocyanine) labelled oligonucleotide probes. RESULT: Duodenal, gall bladder, and bile duct walls were free of bacteria. A dense multispecies bacterial biofilm was present within the pancreatic duct of patients with calcific pancreatitis and within biliary stents, irrespective of diagnosis. The concentration, density, and amenability of the biofilm to FISH and DNA staining declined progressively with the grade of stent occlusion. The lowest detectable bacterial concentrations were found by FISH in completely occluded stents and brown/mixed gall stones. Bacteria were not detectable with FISH in cholesterol gall stones. CONCLUSIONS: A wide range of different branches and groups of bacteria participate in the development of biofilms on the surfaces of foreign bodies, such as biliary stents, mixed gall stones, or calcific pancreatic ducts, but not on the surface of pure cholesterol gall stones. Occlusion of stents leads to progressive extinction of the biofilm and mummification of its components. Deposition of cholesterol or other substances within the biofilm matrix may be a novel mechanism of host defence against bacteria present in these biofilms.

The seroepidemiology of Bordetella pertussis infection in Western Europe.

High titres of pertussis toxin (PT) antibody have been shown to be predictive of recent infection with Bordetella pertussis. The seroprevalence of standardized anti-PT antibody was determined in six Western European countries between 1994 and 1998 and related to historical surveillance and vaccine programme data. Standardized anti-PT titres were calculated for a series of whole-cell and acellular pertussis vaccine trials. For the serological surveys, high-titre sera (> 125 units/ml) were distributed throughout all age groups in both high- (> 90%) and low-coverage (< 90%) countries. High-titre sera were more likely in infants in countries using high-titre-producing vaccines in their primary programme (Italy, 11.5%; Western Germany, 13.3%; France, 4.3%; Eastern Germany, 4.0%) compared to other countries (The Netherlands, 0.5%; Finland, 0%). Recent infection was significantly more likely in adolescents (10-19 years old) and adults in high-coverage countries (Finland, The Netherlands, France, East Germany), whereas infection was more likely in children (3-9 years old) than adolescents in low-coverage (< 90%; Italy, West Germany, United Kingdom) countries. The impact and role of programmatic changes introduced after these surveys aimed at protecting infants from severe disease by accelerating the primary schedule or vaccinating older children and adolescents with booster doses can be evaluated with this approach.

European Sero-Epidemiology Network: standardisation of the assay results for pertussis.

A standardisation process was developed in order to compare and harmonize serological results of pertussis toxin (PT) antibody measurements performed by laboratories using different technical procedures for detection. This involved the development of a common panel, of sera by a designed reference centre, the distribution of the panel to each participating laboratory for testing with their routine methods, the comparison of the obtained results to those of the reference centre, and the calculation of standardisation equations by regressing the quantitative results against those of the reference centre. As a cut-off indicative of protection against pertussis has not yet been defined, a particular emphasis was laid upon achieving standardisation of high titre results that would allow epidemiological evaluations based on the estimation of the incidence of recent infections rather than on the traditional approach of determining the population immunity profile. A generally good agreement was achieved between the participating laboratories, all using ELISA procedures very similar in many crucial aspects, and standardisation equations were produced useful to enable inter-country comparison during the next stages of the European Sero-Epidemiology Network (ESEN) project concerning the serological surveillance of immunity to pertussis in Europe.

Time dependent changes in the concentration and type of bacterial sequences found in cholesterol gallstones.

The role of bacteria in gallstone formation could not be conclusively evaluated until bacterial presence or absence in a stone was consistently shown. Cultural bacteriologic investigations at the time of cholecystectomy, however, led to the assumption that cholesterol gallstones were free of bacteria. In this study, we used a culture independent, molecular genetic approach to detect, quantify, and identify bacteria in cholesterol gallstones from 100 patients at the time of cholecystectomy and 6 months following. Bacterial growth was recorded in the culture in 9 of 100 gallstones; bacterial DNA, however, was detected in 82 of 91 sterile gallstones. High concentrations corresponding to between 10(6) to 10(7) bacteria/g were detected in 11 stones and low concentrations of 10(5) bacteria/g were detected in 71 sterile stones. The infection in stones with a positive bacterial culture was characterized by the predominance of single bacterial sequence(s) of the bacteria cultured. A similar predominance, indicating a recent infection, was found in sterile gallstones with low DNA concentrations. A high diversity of non-repeating bacterial sequences, possibly arising from previous overlapping infections, was found in sterile gallstones with high concentrations of bacterial DNA. After 6 months concentrations of bacterial DNA fell significantly in all groups of gallstones. As bacterial DNA is quickly destroyed upon storage, but is nevertheless readily found in most gallstones at the time of cholecystectomy, there must be a mechanism by which it is replenished. One such mechanism is the frequently reoccurring, possibly self-terminating infection and another one is the permanent colonization of the gallstone with bacteria at low concentrations. Both can promote cholecystolithiasis.

A global gene pool for high-level cephalosporin resistance in commensal Streptococcus species and Streptococcus pneumoniae.

Highly penicillin- and cephalosporin-resistant Streptococcus mitis and Streptococcus oralis were isolated in Spain, Hungary, and Berlin. With chromosomal DNA of these strains, resistant transformants of Streptococcus pneumoniae were obtained that expressed low-affinity variants of penicillin-binding proteins (PBPs) 2x, 1a, 2a, and 2b in different combinations, depending on the selective conditions. The transformants had cefotaxime MICs of up to 6 microg/mL, and those with a low-affinity PBP 2b were highly deficient in penicillin-induced lysis. Sequence analysis of the pbp2x genes confirmed the presence of a global gene pool of penicillin resistance determinants shared by commensal and pathogenic streptococci.

Comparison of screening methods to identify methicillin-resistant Staphylococcus aureus.

Screening methods to identify methicillin-resistant Staphylococcus aureus (MRSA) were compared using 96 isolates representing 17 distinct clones. The sensitivity of four commercial agglutination tests was determined in comparison to the tube coagulation test, and the results related to the presence of the coagulase gene. The broth screening test, agar dilution test and disc diffusion test were carried out, and the results related to the presence of the mecA gene. Mannitol salt agar and Iso-Sensitest agar with varying salt supplements were used. All agglutination tests had high rates of detection of Staphylococcus aureus (95.8-99.0%). Resistance in mecA gene-positive Staphylococcus aureus isolates was correctly detected by the oxacillin broth test, the agar dilution test and the disc diffusion test on mannitol salt agar, whereas on Iso-Sensitest agar detection rates were lower (between 68.5% and 94.4%, depending on the salt supplement). Incubation of the Iso-Sensitest plates for 48 hours significantly improved the rate of detection of resistance, but increased the major error rate up to 71.4%. MecA gene-positive Staphylococcus aureus isolates not detected by the disc diffusion test on Iso-Sensitest agar had significantly lower oxacillin minimal inhibitory concentration values and were significantly less resistant to a variety of antibiotics. Thus, mannitol salt agar might be a suitable medium for use in the disc diffusion and agar dilution test to detect resistance to oxacillin in Staphylococcus aureus.

The effect of amphiphilic polymers on growth of Bordetella pertussis and production of B. pertussis haemagglutinins.

The effect, upon addition to a culture medium of amphiphilic polymers such as partly hydrolysed polyvinyl acetate (PVAc) or partly methylated cellulose (MeCel) on growth and production of haemagglutinins--the filamentous haemagglutinin (FHA) and the pertussis toxin (PT)--has been investigated. As a result, an increase of HA-titer and PT could be achieved. Besides these effects the addition of the amphiphilic polymers stimulated growth of B. pertussis. The above results are comparable to, or even better than, those obtained by addition of Heptakis (2,6-0-dimethyl) beta-cyclodextrin (Me-beta-CD) or polyvinyul alcohols (PVA) which have already been described as compounds to enhance growth and yield of haemagglutinins.