Prevalence of ß-lactamase-producing bacteria in human periodontitis.

BACKGROUND AND OBJECTIVE: Beta-lactam antibiotics prescribed in periodontal therapy are vulnerable to degradation by bacterial ß-lactamases. This study evaluated the occurrence of ß-lactamase-positive subgingival bacteria in chronic periodontitis subjects of USA origin, and assessed their in vitro resistance to metronidazole at a breakpoint concentration of 4 µg/mL. MATERIAL AND METHODS: Subgingival plaque specimens from deep periodontal pockets with bleeding on probing were removed from 564 adults with severe chronic periodontitis before treatment. The samples were transported in VMGA III and then plated onto: (i) nonselective enriched Brucella blood agar (EBBA) and incubated anaerobically for 7 d; and (ii) selective trypticase soy-bacitracin-vancomycin (TSBV) and incubated for 3 d in air + 5% CO2 . At the end of the incubation periods, the bacterial test species were identified and quantified. Specimen dilutions were also plated onto EBBA plates supplemented with 2 µg/mL of amoxicillin, a combination of 2 µg/mL of amoxicillin plus 2 µg/mL of the ß-lactamase inhibitor clavulanic acid, or 4 µg/mL of metronidazole, followed by anaerobic incubation for 7 d. Bacterial test species presumptively positive for ß-lactamase production were identified by growth on EBBA primary isolation plates supplemented with amoxicillin alone and no growth on EBBA primary isolation plates containing both amoxicillin plus clavulanic acid. A subset of such isolates was subjected to nitrocefin-based chromogenic disk testing to confirm the presence of ß-lactamase activity. In vitro resistance to 4 µg/mL of metronidazole was noted when growth of test species occurred on metronidazole-supplemented EBBA culture plates. RESULTS: Two-hundred and ninety-four (52.1%) of the study subjects yielded ß-lactamase-producing subgingival bacterial test species, with Prevotella intermedia/nigrescens, Fusobacterium nucleatum and other Prevotella species most frequently identified as ß-lactamase-producing organisms. Of the ß-lactamase-producing bacterial test species strains recovered, 98.9% were susceptible in vitro to metronidazole at 4 µg/mL. CONCLUSION: The occurrence of ß-lactamase-positive subgingival bacterial species in more than half of the subjects with severe chronic periodontitis raises questions about the therapeutic potential of single-drug regimens with ß-lactam antibiotics in periodontal therapy. The in vitro effectiveness of metronidazole against nearly all recovered ß-lactamase-producing subgingival bacterial species further supports clinical periodontitis treatment strategies involving the combination of systemic amoxicillin plus metronidazole.

Antimicrobial susceptibility of clinically relevant Gram-positive anaerobic cocci collected over a three-year period in the Netherlands.

The susceptibility of 14 species of 115 Gram-positive anaerobic cocci (GPAC) was determined for 14 antibiotics. To assure correct identification, strains were genotypically identified by fluorescence in situ hybridization and sequencing. Susceptibility differences (MIC50 and MIC90) for penicillin G, clindamycin, tigecycline, levofloxacin, amoxicillin-clavulanic acid, cefoxitin, ertapenem, meropenem, metronidazole, and doxycycline were found for the three clinically most relevant GPAC species: Finegoldia magna, Parvimonas micra, and Peptoniphilus harei.

Evaluation of the Vitek 2 ANC card for identification of clinical isolates of anaerobic bacteria.

An evaluation of the Vitek 2 ANC card (bioMérieux, Marcy l'Etoile, France) was performed with 301 anaerobic isolates. Each strain was identified by 16S rRNA gene sequencing, which is considered to be the reference method. The Vitek 2 ANC card correctly identified 239 (79.4%) of the 301 clinical isolates to the genus level, including 100 species that were not represented in the database. Correct species identification was obtained for 60.1% (181/301) of the clinical isolates. For the isolates not identified to the species level, a correct genus identification was obtained for 47.0% of them (47/100), and 16 were accurately designated not identified. Although the Vitek 2 ANC card allows the rapid and acceptable identification of the most common clinically important anaerobic bacteria within 6 h, improvement is required for the identification of members of the genera Fusobacterium, Prevotella, and Actinomyces and certain Gram-positive anaerobic cocci (GPAC).

Comparison of three rapid and easy bacterial DNA extraction methods for use with quantitative real-time PCR.

The development of fast and easy on-site molecular detection and quantification methods for hazardous microbes on solid surfaces is desirable for several applications where specialised laboratory facilities are absent. The quantification of bacterial contamination necessitates the assessment of the efficiency of the used methodology as a whole, including the preceding steps of sampling and sample processing. We used quantitative real-time polymerase chain reaction (qrtPCR) for Escherichia coli and Staphylococcus aureus to measure the recovery of DNA from defined numbers of bacterial cells that were subjected to three different DNA extraction methods: the QIAamp DNA Mini Kit, Reischl et al.'s method and FTA Elute. FTA Elute significantly showed the highest median DNA extraction efficiency of 76.9% for E. coli and 108.9% for S. aureus. The Reischl et al. method and QIAamp DNA Mini Kit inhibited the E. coli qrtPCR assay with a 10-fold decrease of detectable DNA. None of the methods inhibited the S. aureus qrtPCR assay. The FTA Elute applicability was demonstrated with swab samples taken from the International Space Station (ISS) interior. Overall, the FTA Elute method was found to be the most suitable to selected criteria in terms of rapidity, easiness of use, DNA extraction efficiency, toxicity, and transport and storage conditions.

The identification of anaerobic bacteria using MALDI-TOF MS.

Matrix Assisted Laser Desorption and Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) has gained more and more popularity for the identification of bacteria. Several studies show that bacterial diagnosticis is being revolutionized by the application of MALDI-TOF MS. For anaerobic bacteria, MALDI-TOF MS has been used for the identification of Prevotella spp., Fusobacterium spp., Clostridium spp., Bacteroides spp. and Gram-positive anaerobic cocci. However, to identify bacteria reliably, an extensive database is essential. For routine identification of anaerobic bacteria available databases need to be optimised.

Assessment of the microbiota of a mixed infection of the tongue using phenotypic and genotypic methods simultaneously and a review of the literature.

We assessed the microbiota of a tongue abscess in which twelve different aerobic and anaerobic bacteria were identified using fluorescent in situ hybridisation (FISH), sequencing of the 16S rRNA gene and phenotypic methods. By applying the 16S rRNA based probes directly on the clinical material, a quick insight of the bacteria present was obtained and the species which were not cultured but present in the abscess were identified.

Is bacteriologic surveillance in endoscope reprocessing stringent enough?

Endoscopes, including duodenoscopes, are medical devices that are frequently associated with outbreaks of nosocomial infections. We investigated an outbreak of multidrug-resistant PSEUDOMONAS AERUGINOSA sepsis affecting three patients after endoscopic retrograde cholangiopancreaticography (ERCP). Epidemiologic investigation supplemented by molecular typing revealed that one ERCP scope was the source of infection with P. AERUGINOSA. No contamination with this microorganism was found after screening of washer-disinfectors, connecting tubes, and environmental surfaces in the endoscopy center. PSEUDOMONAS isolates from blood and endoscope channels before gas sterilization with ethylene oxide (ETO) were characterized by molecular typing as "linked isolates". Though the current surveillance system did not prevent the infections in three patients, our microbiological surveillance protocol with routine culturing of endoscopes was helpful in detecting the source of contamination and probably avoided numerous cross-contaminations in other patients who underwent ERCP procedures with endoscopes.

Endoscope disinfection and its pitfalls--requirement for retrograde surveillance cultures.

BACKGROUND AND STUDY AIMS: Several endoscopy-related outbreaks of infection have been reported in recent years. For early recognition of inadequate disinfection of endoscopes we designed a microbiological surveillance system to evaluate the efficacy of the cleaning and disinfection procedure, and to trace disinfection problems to individual endoscopes or washer-disinfectors. METHODS: Our surveillance protocol included anterograde and retrograde sampling, a decision algorithm, genetic fingerprinting, and scanning electron microscopy. RESULTS: Over a period of 29 months we found an increasing number of patient-ready endoscopes testing positive for Candida species other than albicans, especially C. parapsilosis. These yeasts were also isolated from the washer-disinfectors. The number of positive tests for Candida species varied from 1 out of 21 to 14 out of 27 samples from nine frequently used endoscopes. The number of colony-forming units per milliliter ranged from 1 - 10 to 3000 for endoscopes and 0.002 to 0.06 for the washer disinfectors. DNA fingerprinting was not able to discriminate different strains within C. parapsilosis. CONCLUSIONS: Our protocol was able to detect a structural problem in the endoscope disinfection process. Retrograde sampling was crucial for this purpose, because it has much higher sensitivity than anterograde sampling. Endoscopes with damaged working channels are probably the source of the contamination problem with Candida species.

Experiences with the Dutch Working Party on antibiotic policy (SWAB).

The Dutch Working Party on Antibiotic Policy (Stichting Werkgroep AntibioticaBeleid, SWAB) was founded in 1996 as an initiative of the Society for Infectious Diseases, the Dutch Society for Medical Microbiology, and the Dutch Association of Hospital Pharmacists. Its primary goal is to contribute to the containment of antimicrobial resistance and the expanding costs incurred for the use of antibiotics. SWAB is the Intersectoral Coordinating Mechanism (ICM) for the Netherlands, and it is at present the National Antimicrobial Resistance (AMR) Focal Point. It coordinates the national surveillance of antibiotic resistance, in collaboration with the National Institute for Public Health and the Environment(RIVM), coordinates the surveillance of the use of antibiotics,and runs a guideline development programme. Information about consumption of antimicrobial agents and antimicrobial resistance among medically important bacteria is presented annually in NethMap. Over the past decade, outpatient consumption of antibiotics has risen only slightly, but in the hospital setting there was an overall significant increase in antibiotic use, due mainly to the steady reduction in the average length of patient hospital stays. In 2006 we introduced our electronic national antibiotic guide 'SWAB-ID' for the antibiotic treatment and prophylaxis of common infectious diseases in hospitals.

[Strength in numbers: illness-causing biofilms]. / Teamwork in ziekmakende biofilms.

Microbial infections constitute an important reason for medical treatment, especially in dentistry. Ideas about the role played by bacteria in the development of diseases have changed steadily during the past centuries. At the present time much attention is being devoted to the role of biofilms due to their illness-causing influence with respect to stitches on hard tissue and on oral implants, knee-, hip-, and voice prostheses. In biofilms, bacteria function and communicate in organized extrapolymeric structures, attached to a surface. Biofilms provide bacteria with protection against the host's immune system and antibacterial chemicals. By gaining insights into the creation and functioning of biofilms, it will be possible to develop better antibacterial therapies.

Management of community-acquired pneumonia in adults: 2016 guideline update from the Dutch Working Party on Antibiotic Policy (SWAB) and Dutch Association of Chest Physicians (NVALT).

The Dutch Working Party on Antibiotic Policy in collaboration with the Dutch Association of Chest Physicians, the Dutch Society for Intensive Care and the Dutch College of General Practitioners have updated their evidence-based guidelines on the diagnosis and treatment of community-acquired pneumonia (CAP) in adults who present to the hospital. This 2016 update focuses on new data on the aetiological and radiological diagnosis of CAP, severity classification methods, initial antibiotic treatment in patients with severe CAP and the role of adjunctive corticosteroids. Other parts overlap with the 2011 guideline. Apart from the Q fever outbreak in the Netherlands (2007-2010) no other shifts in the most common causative agents of CAP or in their resistance patterns were observed in the last five years. Low-dose CT scanning may ultimately replace the conventional chest X-ray; however, at present, there is insufficient evidence to advocate the use of CT scanning as the new standard in patients evaluated for CAP. A pneumococcal urine antigen test is now recommended for all patients presenting with severe CAP; a positive test result can help streamline therapy once clinical stability has been reached and no other pathogens have been detected. Coverage for atypical microorganisms is no longer recommended in empirical treatment of severe CAP in the non-intensive care setting. For these patients (with CURB-65 score >2 or Pneumonia Severity Index score of 5) empirical therapy with a 2nd/3rd generation cephalosporin is recommended, because of the relatively high incidence of Gram-negative bacteria, and to a lesser extent S. aureus. Corticosteroids are not recommended as adjunctive therapy for CAP.

Development of 16S rRNA-based probes for the identification of Gram-positive anaerobic cocci isolated from human clinical specimens.

Fluorescent probes targeted at 16S rRNA were designed for Peptostreptococcus anaerobius and Peptostreptococcus stomatis (Pana134), Parvimonas micra (Pamic1435), Finegoldia magna (Fmag1250), Peptoniphilus asaccharolyticus (Pnasa1254), Peptoniphilus ivorii (Pnivo731), Peptoniphilus harei (Pnhar1466), Anaerococcus vaginalis (Avag1280) and Anaerococcus lactolyticus (Alac1438), based on the 16S rRNA sequences of reference strains and 88 randomly chosen clinical isolates. These strains were also used for validation of the probes. Application of the probes to an additional group of 100 clinical isolates revealed that 87% of Gram-positive anaerobic cocci (GPAC) could be identified with this set of probes. The 16S rRNAs of 13 clinical isolates that could not be identified were sequenced. Most of these isolates were GPAC that were not targeted by the probes. No clinical isolates of Pn. asaccharolyticus were encountered. Near full-length sequences were obtained from 71 of 101 (n = 88 + 13) sequenced clinical isolates. Of these, 25 showed <98% similarity with the homologues of the closest established species. The Fmag1250, Pamic1435, Pnhar1466, Pana134, Pnasa1254 and Pnivo731 probes allowed reliable identification and hybridised with all corresponding isolates. The Avag1280 and Alac1438 probes failed to hybridise with two isolates and one isolate, respectively, because of intra-species variation. However, overall, the set of probes yielded fast and reliable identification for the majority of clinical isolates.

Reliability of assessment of adherence to an antimicrobial treatment guideline.

Assessment procedures for adherence to a guideline must be reliable and credible. The aim of this study was to explore the reliability of assessment of adherence, taking account of the professional backgrounds of the observers. A secondary analysis explored the impact of case characteristics on assessment. Six observers (two hospital pharmacists, two internists and two clinical microbiologists) assessed a random sample of 22 prescriptions made to infectious disease cases admitted to a department of internal medicine between February and August 2001. Agreement between observers with regard to adherence of these prescriptions to guideline recommendations concerning drug choice, duration of treatment, dosage and route of administration was measured using Cohen's kappa. Case characteristics were compared between cases where observers agreed and disagreed with two-sided Fisher's exact test. Agreement between all professionals was moderate for drug choice (0.59), fair for duration of therapy (0.36), moderate for dosage (0.48), and fair for route of administration (0.37). Agreement on drug choice was good within (0.75 and 0.83) and between (0.74) the internists and the hospital pharmacists, but was less within (0.31) the clinical microbiologists and between the clinical microbiologists and the internists (0.44) and the hospital pharmacists (0.42). Within the clinical microbiologists, agreement was good for dosage (0.79) and route of administration (0.66). There was frequent disagreement between observers regarding cases with combination therapy and non-immunocompromised patients. Despite the small number of cases, our results suggest that internists and hospital pharmacists can reliably be used to assess adherence for drug choice. The level of agreement seems to be affected by combination therapy and the immune status of the patient.

[Optimizing the antibiotics policy in The Netherlands. VIII. Revised SWAB guidelines for antimicrobial therapy in adults with community-acquired pneumonia]. / Optimaliseren van het antibioticabeleid in Nederland. VIII. Herziene SWAB-richtlijnen voor antimicrobiële therapie bij thuis opgelopen pneumonie.

The Dutch Working Party on Antibiotic Policy (SWAB) has revised the 1998 guideline for community-acquired pneumonia (CAP) in light of changing resistance patterns for common pathogens and new developments in epidemiology, diagnostic testing and treatment strategies. The current guideline is applicable to both primary and inpatient care, and has been developed by delegates of all professional organisations involved in the treatment of CAP, following recommendations for evidence-based guideline development. Assessment of a patient's 'severity of illness' at presentation is considered important when choosing an optimal empirical antibiotic regimen for CAP. Severely-ill patients should be treated with antibiotics covering the most important expected pathogens, including Legionella. Assessment of the severity of illness may be facilitated by the use of validated scoring systems like the pneumonia severity index and the 'confusion, urea, respiratory-rate, blood-pressure, 65-years-of-age' (CURB-65) score. Patients can also be stratified based on their location during treatment: in the community, a normal ward or an intensive-care unit. Legionella urine antigen testing is considered an important tool in the process of deciding on an optimal antibiotic regimen for CAP. Empirical therapy should be replaced with pathogen-directed therapy if the causative agent is identified.

Tobramycin in patients with cystic fibrosis. Adjustment in dosing interval for effective treatment.

The efficacy of the dosing regimen of tobramycin was investigated in 28 patients with cystic fibrosis who had an acute exacerbation of chronic pulmonary infection with Pseudomonas aeruginosa. The initial dose of tobramycin was 3.3 mg/kg of body weight three times daily (ie, 10 mg/kg/day). A highly significant relationship was found between the serum concentration of tobramycin before the dose and the change in the forced expiratory volume in one second (FEV1), both measured on the tenth day of treatment (rs = 0.75; p less than 0.001). In nine of the 16 patients who had a six-hour serum concentration of 1 mg/L or less on the tenth day of treatment, the eight-hour dosing interval of tobramycin was shortened to achieve a serum concentration of tobramycin of about 1 mg/L before the dose. In the other seven patients, the dosage of tobramycin was not changed. On the 20th day, seven of the nine patients in whom the dosing interval was shortened exhibited an increase in FEV1 of 20 percent or more. Such an increase was observed only in one of the seven patients in whom the dosing interval was not reduced (p less than 0.05). We conclude that individualizing the dosage of tobramycin in patients with cystic fibrosis results in a better clinical outcome.

Pharmacokinetics of tobramycin in patients with cystic fibrosis. Implications for the dosing interval.

The pharmacokinetics of tobramycin were evaluated in 15 patients (8 to 22 years of age) with cystic fibrosis (CF). A dose of 3.0 to 3.3 mg/kg of body weight was given intravenously over 20 minutes, and concentrations in serum were followed up to eight hours after initiation of the infusion. In the calculation of pharmacokinetic parameters, a two-compartment open model was used. The elimination half-life of the drug was highly inversely correlated with age (p less than 0.0004), and body weight (p less than 0.00002). Total body clearance (TBC), and volume of distribution at steady state (VDSS) were directly correlated with age and body weight. However, when TBC and VDSS were corrected for BSA, no correlation could be demonstrated. The mean one-hour and eight-hour serum concentrations of tobramycin were 5.40 and 0.45 microgram X ml-1, respectively. Between patients, considerable differences were found in the time after administration at which the serum concentration decreased below 1 microgram X ml-1. This interpatient variation has clinical implications for tobramycin therapy in CF, in particular for the dosing interval.

Use of protein profiles to identify Acinetobacter calcoaceticus in a respiratory care unit.

The presence of acinetobacters in a respiratory care unit was prospectively studied because of an increase in the number of isolations of Acinetobacter calcoaceticus. Cell envelope protein electrophoresis was used to distinguish strains. Eleven protein patterns were observed in isolates from patients and their environment. One pattern (pattern 1) was seen in several patients and environmental samples. Another pattern (pattern 2) was identified repeatedly in samples from skin and mucous membranes of patients in the same ward. After thorough cleaning was undertaken throughout the unit, the pattern 1 strain was no longer cultivated from clinical samples. It is concluded that cell envelope protein electrophoresis is a useful method for tracing epidemic strains of A calcoaceticus.

Cell envelope protein profiles of Acinetobacter calcoaceticus strains isolated in hospitals.

The cell envelope protein patterns of 78 strains of Acinetobacter calcoaceticus, mainly isolated in hospitals, were analysed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). The patterns were stable and reproducible. Comparison of the protein profiles made possible differentiation between two groups of strains. The patterns of the first group could be classified on the basis of concordance. Some profiles appeared to be associated with the epidemiological origin of the strains. The second group consisted of strains with unique patterns which could not be classified. Comparison of SDS-PAGE patterns appears to be a suitable method for the relative classification of A. calcoaceticus strains of nosocomial origin.

Faecal carriage of aerobic gram-negative bacilli and drug resistance of Escherichia coli in different age-groups in Dutch urban communities.

Faecal carriage rates for aerobic gram-negative bacilli and for antibiotic-resistant Escherichia coli were determined in samples of the Dutch urban population. Of the 741 people studied, 64 were under 1 year old (infants), 53 were 1-5 years old, and there were approximately 200 in each of the age-ranges 6-17 years, 18-49 years and 50-80 years. Carriage rates of E. coli were similar (87-93%) in all age groups, but Klebsiella and Enterobacter species were found more often in specimens from infants and young children than in those from older people. E. coli strains resistant to tetracycline, ampicillin, or sulphamethoxazole or to any one or more of them were detected in 42%, 26%, 46% and 66% respectively of the specimens found to contain E. coli. The corresponding figures for the finding of E. coli populations that were predominantly resistant to tetracycline, ampicillin or sulphamethoxazole were 12%, 6% and 20%. The frequency of resistance to any of these drugs was not related to age or sex of the subjects. All E. coli isolates were sensitive to gentamicin. Among the 577 subjects aged 6-80 years from whose samples E. coli was isolated were 19 who had taken antibacterial drugs in the previous 30 days and 11 who were involved in cattle farming; carriage rates for tetracycline-resistant and sulphonamide-resistant E. coli were significantly higher among these 30 than in the other 547.