Vancomycin-dependent enterococcus.
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Anti-Bacterial Agents↗
Biomedical subjects
C T Keane
Publications and source records attributed to C T Keane.
Recurrence of Helicobacter pylori infection after successful eradication: nature and possible causes.
Recurrence of Helicobacter pylori infection after successful eradication occurs and is associated with relapse of gastroduodenal diseases. The aims of this paper were to assess the incidence and identify the nature and possible causes of recurrence of the infection. A broad-based Medline search was performed to identify all related publications addressing recurrence of the infection between 1986 and 1995. The 12-month recurrence rate varied among the different studies from 0 to 41.5%. A few studies showed 18- to 24-month recurrence rates, which ranged between 0 and 21.4%. Limited data, obtained using molecular fingerprinting techniques, have shown that in most cases recurrence is due to recrudescence of the original strain; a few cases appear to be due to reinfection with a new strain. Recrudescence is most likely during the first 12 months after apparent eradication. Despite the high sensitivity and specificity of the available individual tests for detecting H. pylori infection in untreated patients, no technique alone is sensitive enough to monitor eradication when the four-week-rule definition for eradication is used. A combination of two or more techniques increases sensitivity. Sensitivity and specificity are increased when biopsies are taken from both gastric antrum and corpus. The best treatments have the lowest recurrence rates and recurrence is rare when the eradication rate is over 90%. Individual susceptibility and reexposure to H. pylori are suggested as two major causes of reinfection.
Breath Tests↗
Metronidazole resistance reduces efficacy of triple therapy and leads to secondary clarithromycin resistance.
There has been a significant increase in the prevalence of H. pylori resistance to metronidazole in recent years, while clarithromycin resistance is still relatively rare. In this study we assessed: (1) the effect of primary H. pylori resistance to metronidazole and clarithromycin on the clinical efficacy of a one-week regimen consisting of omeprazole, metronidazole, and clarithromycin; and (2) the rate of acquisition of secondary antimicrobial resistance after treatment failure. Eighty-seven patients with duodenal ulceration or nonulcer dyspepsia were included in the study. The primary metronidazole and clarithromycin resistance rates were 35.6% and 3.4%, respectively (all three pretreatment clarithromycin resistant strains had concurrent metronidazole resistance). H. pylori was eradicated in 81.6% of patients. The eradication rate for fully sensitive isolates was 98.2% (55/56) but was significantly reduced to 57.1% (16/28) for isolates that were resistant to metronidazole alone and 0% (0/3) in cases of dual resistance (P < 0.001). Secondary resistance to clarithromycin was acquired in 58.3% of cases of treatment failure. In areas of high prevalence of primary metronidazole resistance, this is a significant cause of treatment failure with this triple therapy regimen. This leads to the selection of strains with dual resistance that are difficult to eradicate and may contribute to an increase in the prevalence of clarithromycin resistance. In such areas an alternative first-line treatment should be prescribed.
Adult↗
The use of RAPD-PCR as a typing method for Serratia marcescens.
Serratia marcescens has emerged in the last few years as an important nosocomial pathogen. Many methods for typing this organism have been described. In this study the random amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR) was shown to be a convenient typing method for S. marcescens. Different combinations of primers previously used for typing other gram-negative bacilli were assessed. The combination of primer HLWL-74 and 1254 gave distinguishable patterns for different serotypes and proved to be the most satisfactory. By applying this combination to 175 isolates of S. marcescens, which could be classified into 38 groups on the basis of serotyping and phage typing, 73 different RAPD patterns with good reproducibility were obtained. This is, to our knowledge, the first application of the method to a large collection of S. marcescens representing a wide range of serotypes.
Bacteriophage Typing↗
Incidence and detection of multi-drug-resistant enterococci in Dublin hospitals.
In February 1994, an outbreak of vancomycin-resistant Enterococcus faecium (VREM) occurred in the oncology unit of a Dublin hospital. Between February and July 1994, VREM was isolated from 18 patients, one staff member and 14 environmental sites within the unit. The isolates also had high-level aminoglycoside and penicillin resistance. Three pulsed-field gel electrophoresis (PFGE) types were identified, two of them from multiple patients and environmental sites. Plasmid typing allowed subdivision of PFGE types. A retrospective study of enterococci isolated from blood cultures between January 1991 and January 1994 showed that, before the outbreak, fewer than 2% of isolates were vancomycin-resistant but that the incidence of high-level gentamicin resistance had increased from 17% to 60% and ampicillin resistance from 22% to 51%. Among clinically significant non-blood-culture enterococci isolated between September and December 1993, fewer than 1% were vancomycin-resistant, 13% were ampicillin-resistant and 44% highly gentamicin-resistant. None produced beta-lactamase. High-content gentamicin disks (120 micrograms) and low-content vancomycin disks (5 micrograms) allowed simple, reliable detection of resistant enterococci. MICs of vancomycin and teicoplanin determined by agar dilution and E-test agreed well, but values tended to be slightly lower by E-test.
Ampicillin Resistance↗
Clarithromycin resistance in Helicobacter pylori: prevalence in untreated dyspeptic patients and stability in vitro.
Susceptibilities to clarithromycin and metronidazole of 444 Helicobacter pylori isolates cultured from antral biopsies of 444 dyspeptic patients were determined by disc diffusion tests (15 mu g disc for clarithromycin, 5 mu g disc for metronidazole). Susceptibility of 46 of these isolates to erythromycin (5 mu g disc) was also tested. Minimal inhibitory concentrations (MICs) of clarithromycin for 42 selected isolates were determined by a plate dilution method. A zone diameter of 30 mm was defined as a 'cut-off' size differentiating susceptibility and resistance of the organism to clarithromycin, by comparing results obtained with the two methods. Of the 444 isolates, 424 (95.5%) were highly sensitive to clarithromycin, with zone diameters ranging from 30 to 98 mm. Twenty isolates (4.5%) were defined as resistant to clarithromycin, with zone diameters ranging between 6 and 28 mm. The incidence of clarithromycin resistance was similar in men and women and in different age groups, and was not significantly different between patients with peptic ulcer and non-ulcer dyspepsia. Among the 444 isolates, 168 (37.8%) were metronidazole resistant. There was cross resistance between clarithromycin and erythromycin, but not between clarithromycin and metronidazole. Stability of clarithromycin resistance was evaluated by the disc diffusion test and confirmed by the plate dilution method. Among the 20 clarithromycin-resistant isolates, nine (45%) reverted to be sensitive after 25 subcultures on drug-free agar. The findings in this study indicate that the incidence of clarithromycin-resistant H. pylori in untreated dyspeptic patients is low. Cross-resistance occurs between macrolides and resistance to clarithromycin in some strains is reversible.
Adult↗
Increased expression of Fc gamma receptors on neutrophils and monocytes may reflect ongoing bacterial infection.
The Fc gammaR receptors for IgG, Fc gammaRI, Fc gammaRII and Fc gammaRIII were measured on neutrophils and monocytes from 36 patients suspected of systemic infection. These results were compared with 30 blood donor controls to assess the level of expression as an early indicator of bacterial infection. Fc gammaRI expression on neutrophils was found to be significantly increased from patients with systemic or localised infections, when compared to non-infected patient group, i.e., patients with no cultural evidence of bacterial infections, (p=0.02, p=0.04) or normal controls (p<0.0001, p=0.0005). Fc gammaRI expression on monocytes was also significantly increased in both of the infected groups compared to normal controls (p<0.0001, p=0.001); however, no significant difference could be seen when compared with the non-infected patients. Fc gammaRIII was found to be significantly increased on a subset of monocytes in patients with systemic or localised infections compared to the non-infected group (p=0.009, p=0.006) and compared to the normal controls (p=0.009, p=0.003). Infections caused by gram-negative bacilli induced a higher Fc gammaR response than infection with either streptococci or staphylococci. These data suggest that the measurement of Fc gammaRI on neutrophils and Fc gammaRIII on monocytes may be a useful rapid indicator of bacterial infection.
Bacterial Infections↗
Are hydrogen breath tests valid in the elderly?
Hydrogen breath testing (HBT) is frequently used as an alternative to small bowel aspiration in the diagnosis of small intestinal bacterial overgrowth (SIBO). The role of the glucose HBT was assessed in 30 elderly patients. A positive HBT was recorded in 15 of 20 SIBO cases and 7 of 10 culture negatives (sensitivity 75% and specificity 30%). The correlation coefficients between hydrogen gas (H2) rise and total bacterial count (r = 0.21) and H2 rise and anaerobic count (r = 0) were not significant. Fasting H2 levels were raised in only 4 of the 20 SIBO cases. This study indicates that the HBT is not reliable in the diagnosis of SIBO in the elderly. There was no evidence from the data that different H2 levels or bacterial counts would significantly alter the reliability of the HBT. This work suggests that factors other than small bowel bacteria are involved in the production and expiration of H2 in the elderly, and that these factors need to be considered in the interpretation of this breath test.
Aged↗
Effect of Bacteroides melaninogenicus culture supernatant and deconjugated bile salt on lipid absorption.
Lipid malabsorption is a common clinical manifestation of small bowel bacterial overgrowth. Its pathogenesis, however, remains controversial. Bacteroides melaninogenicus ssp. intermedius, an anaerobic bacterium, is commonly isolated from the upper bowel of patients with small intestinal bacterial overgrowth. The effects of a culture supernate of this organism and deoxycholate, an unconjugated bile salt, on intestinal oleic acid absorption were examined using a rat closed-loop model. The supernatant reduced the in vitro uptake of oleic acid by 19% (P< 0.001). Deoxycholate did not significantly reduce the lipid absorption. Combined supernate and deoxycholate did not have an additive effect on absorption of oleic acid. We conclude that anaerobic bacterial products may contribute to the malabsorption of lipid in the setting of bacterial overgrowth of the small bowel.
Animals↗
An epidemiological study of Candida species infection in cancer patients using genetic fingerprinting and morphotyping.
During a six-week period a cluster of four cases of Candida fungaemia occurred in a mixed haematology/oncology unit of a large Dublin teaching hospital. A study was conducted to determine whether the cluster of cases was caused by a particular strain. Nine patients were studied; five who were colonized with Candida spp. and four who developed Candida fungaemia. Twenty-two clinical isolates of Candida spp. were collected and identified. Three of the patients with fungaemia yielded Candida albicans from blood cultures and C. tropicalis was isolated from the fourth patient. C. albicans isolates were serotyped, morphotyped and analysed by DNA fingerprinting of total cellular DNA using the cloned C. albicans-specific, mid-repeat sequence element 27A as a molecular probe. All C. albicans isolates were of serotype A. Eight distinguishable types were identified by both morphotyping and DNA typing from 19 C. albicans isolates recovered from seven individual patients, although there were several discrepancies. Of three patients from whom two or more isolates of C. albicans were recovered on separate occasions, two yielded recurrent isolates with different morphotype codes. However, in both cases, the recurrent isolates from individual patients yielded indistinguishable, or closely related, DNA fingerprint profiles. Both morphotyping and DNA fingerprint analysis readily distinguished the three blood culture isolates of C. albicans. We conclude that the Candida spp. infections in the unit were not due to cross-infection and were probably related to the patients' indigenous flora.
Candida↗
Rapid detection of meningococci from petechiae in acute meningococcal infection.
In order to evaluate the diagnostic usefulness of Gram-staining films from petechial lesions in suspected meningococcal infection, data from 52 patients with confirmed infection were reviewed. Gram-negative diplococci were found in specimens from skin films in 80% (24/30) patients with petechiae. This is significantly better than results reported for Gram-staining of needle aspirates from petechiae (46%; 12/26). Positive skin films were obtained from 89% (17/19) blood culture negative cases and 85% (17/20) CSF negative cases. In 14 cases meningococcal infection was identified only by skin films. Skin film results were not significantly affected by previous antibiotic. Gram-staining of films from petechial lesions in suspected meningococcal infection is a very rapid and effective investigation. Blood culture, CSF examination and culture, and skin films each identified meningococcal infection not identified by the other two investigations.
Acute Disease↗
The in-vitro susceptibilities of vaginal lactobacilli to four broad-spectrum antibiotics, as determined by the agar dilution and E test methods.
The minimum inhibitory concentrations (MICs) of cefaclor, co-amoxiclav, clarithromycin and ciprofloxacin for 59 strains of vaginal lactobacilli were determined by both the reference agar dilution and E test methods. With the exception of clarithromycin, there was poor correlation between the results obtained by the two techniques. This was most apparent for the beta-lactams studied, the MICs of cefaclor as determined by the E test being particularly difficult to define. The stability of antimicrobial gradients in the E test may cause problems when testing slow-growing bacteria and/or organisms which grow only under anaerobic conditions. Accordingly, only those MICs determined by the agar dilution method are reported. The percentages of susceptible isolates were as follows: clarithromycin, 100; co-amoxiclav, 100; cefaclor, 20; and ciprofloxacin, 4. The administration of antimicrobials, such as ciprofloxacin and cefaclor, which have poor activities in vitro against lactobacilli, may therefore be advantageous to the host because it allows the protective effects of the normal vaginal flora to be preserved.
Agar↗
Recrudescence of Helicobacter pylori after apparently successful eradication: novel application of randomly amplified polymorphic DNA fingerprinting.
The aim of this study was to find out if reinfection or recrudescence accounted for the recurrence of Helicobacter pylori infections after apparent eradication of the bacterium. Three hundred and twenty patients were treated with colloidal bismuth subcitrate (120 mg four times daily for four weeks), metronidazole and tetracycline (400 mg and 500 mg, respectively, thrice daily for the first week). H pylori was eradicated four weeks after the end of treatment as assessed by the rapid urease test, histological examination, Gram staining, and culture. However, the infection recurred in 29 (9.1%) of the patients one year after apparent eradication. Pre and posteradication isolates from five patients were available. DNA was extracted and used for restriction endonuclease analysis with Hind III and Hae III, and for polymerase chain reaction (PCR) based randomly amplified polymorphic DNA fingerprinting with a combination of two 10 nucleotide primers. Sodium dodecyl sulphate polyacrylamide gel electrophoretic analysis was performed also. Randomly amplified polymorphic DNA fingerprinting was unique in that it yielded highly discriminatory fingerprints, which showed that the pretreatment and recurrent isolates obtained from each of the five patients were indistinguishable from one another. This shows that recurrence of H pylori infection is probably caused by recrudescence and that the discriminatory power of randomly amplified polymorphic DNA fingerprinting is a practicable and discriminatory typing scheme for H pylori.
Adult↗
Eradication rate of Helicobcter pylori.
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Colony Count, Microbial↗
Recrudescence of Helicobacter pylori infection in patients with healed duodenal ulcer after treatment with different regimens.
OBJECTIVE: To determine the 12-month posttherapy recurrence (recrudescence) of Helicobacter pylori in patients with healed duodenal ulcer after apparent eradication of the organism with anti-H. pylori treatment. The influence of original anti-H. pylori treatment regimens on the recrudescence was also evaluated. METHODS: One hundred and ninety patients who had duodenal ulcer healed and H. pylori eradicated (as assessed by four routine techniques 4 wk after the end of anti-H. pylori therapy) with one of five regimens were studied. The five regimens were: 1) colloidal bismuth subcitrate (CBS) 120 mg; 2) CBS plus amoxicillin (500 mg); 3) CBS plus metronidazole (400 mg); 4) CBS plus metronidazole and amoxicillin; and 5) CBS plus metronidazole and tetracycline (500 mg). CBS was taken four times daily for 4 wk, and antibiotics were taken three times daily for the first week. The patients were re-endoscoped, and the status of H. pylori, duodenal ulcer, and gastritis was assessed after a period of follow-up (mean 14 months after commencement of treatment). RESULTS: H. pylori infection recurred in 36 (18.9%) of these patients. Recrudescence rate with monotherapy was 47.1%, with dual therapy 29.2-35% and with triple therapy 9.2-14.3%. Nineteen (52.7%) of the 36 patients with recrudescent infection had ulcer relapse, and the rate for H. pylori-negative patients was 3.2% (5/154). CONCLUSION: Recrudescence of H. pylori infection after apparent eradication can occur, but it could be that the treatment was only suppressing the organism. The definition of eradication of H. pylori infection may need to be revised, and more sensitive techniques to assess eradication of H. pylori are required.
Adult↗
Culture of Helicobacter pylori under aerobic conditions on solid media.
The aim of the present study was to culture Helicobacter pylori under aerobic conditions and to investigate the characteristics of the organism when cultured aerobically. Most (22 of 23) of the Helicobacter pylori isolates grew under aerobic conditions, but with reduced viable cell counts. Blood agar was more suitable than chocolate agar. The morphological and enzymatic characteristics as well as the protein profiles of each organism were identical under aerobic and microaerophilic conditions. However, haemolysis of Helicobacter pylori was delayed under aerobic conditions. The MIC of metronidazole was slightly lower for some strains under aerobic conditions. These findings indicate that Helicobacter pylori is not only a microaerophilic organism but also adapts to aerobic conditions, which may have some important implications in microbiological and epidemiological studies.
Anaerobiosis↗
Staphylococcus aureus phage typing, antimicrobial susceptibility patterns and patient data correlated using a personal computer: advantages for monitoring the epidemiology of MRSA.
Staphylococcus aureus, especially methicillin-resistant S. aureus (MRSA) is an important nosocomial pathogen. A problem encountered in the control of staphylococcal nosocomial infection is the difficulty correlating data available from antimicrobial susceptibility patterns (usually available locally) with phage typing patterns which are generally determined in a reference laboratory. Data problems are exaggerated because many patients have numerous samples taken over long periods of time. This paper describes the use of a database, 'DataEase', on a personal computer to correlate available data with patient demographics and to present the resulting information in whatever format is required. The information might be presented as the phage pattern of each isolate from patients in a particular unit per month or as a combination of the phage types and antimicrobial susceptibility patterns of isolates from a particular unit. The system can be used to generate a list of all isolates for phage typing in a format that allows the phage typing pattern to be recorded directly onto the list worksheet. In addition to providing clinically relevant reports, the system simplifies the collation of epidemiological information, data from which showed that since 1987 the incidence of MRSA has been rising in the group of hospitals served by this laboratory; MRSA of phage type 83A became a problem during 1990 and 1991; the incidence of gentamicin-sensitive phage type non-typable MRSA increased fourfold between 1988 and 1991; and the incidence of gentamicin-resistant MRSA rose sharply in 1992.
Bacteriophage Typing↗
Meningococcal disease in childhood--a regional study in Ireland.
A retrospective study of microbiology laboratory records of culture-confirmed cases of meningococcal disease in children under 14 years of age, admitted to four Dublin hospitals, was conducted for the period 1981-1991 inclusive. The study aimed to describe the epidemiology of meningococcal disease in childhood and to assess the potential of meningococcal group A and C vaccine in preventing disease. There were 406 cases of meningococcal disease of which 319 (78.6%) were in children under 5 years of age. The meningitis to septicaemia ratio was almost 4:1 (320 vs. 86 cases). Of the 406 cases, 216 (53.2%) cases occurred during the period November to March. The age-specific annual incidence rates for the Eastern Health Board region served was 64.2 per 100,000 under 1 year of age and 24.6 per 100,000 under 5 years of age. A relative increase in disease caused by meningococcal serogroup C was observed during the period of the study. Only 15% all cases could have been prevented by a policy of universal meningococcal group A and C immunisation at 2 years of age. Such a policy, therefore, is not recommended. A vaccine for preventing disease caused by meningococcal group B is urgently required.
Adolescent↗