Implications of new European Union driving regulations on patients with Type 1 diabetes who participated in the Diabetes Control and Complications Trial

AIMS

Recurrent severe hypoglycaemia in a patient with diabetes is strongly associated with a crash risk while driving. To help ensure road safety, recent changes were made to European Union driving regulations for patients with diabetes. These included the recommendation that more than one episode of severe hypoglycaemia within 12 months would lead to the loss of a driving licence. This study has assessed the impact of this regulation if applied to patients who participated in the Diabetes Control and Complications Trial.

METHODS

All patients in the Diabetes Control and Complications Trial were assumed to be drivers. Repeated hypoglycaemic episodes within a year were determined during the mean 6.5 years of the study.

RESULTS

Of the 1441 patients in the Diabetes Control and Complications Trial, 439 (30%) had more than one severe hypoglycaemic episode during a 12-month period of their study participation. Amongst the study groups, 312/711 (44%) of intensively treated and 127/730 (17%) of conventionally treated patients would have lost their licence at some point during the trial. The risk of licence loss increased with lower mean HbA1c , longer duration of diabetes and younger age (all P < 0.001).

CONCLUSIONS

More than one episode of severe hypoglycaemia within a year was a frequent event in subjects in the Diabetes Control and Complications Trial, especially in intensively treated patients. If applied to current practice, improving road safety through these changes to European Union regulations could have a substantial impact on drivers who have Type 1 diabetes. This emphasizes the need to take into account the potential effects of severe hypoglycaemia in those who rely on a driving licence.

Daptomycin in endocarditis and bacteraemia: a British perspective

Assessment of the place of daptomycin in the treatment of endocarditis and bacteraemia requires assimilation of data from one open-label randomized comparative clinical trial sized for equivalence, from registry data and from case reports. Selected relevant animal models and in vitro data are also considered in an effort to produce an integrated assessment of the current place of daptomycin in treatment. The evidence for the use of daptomycin is best in Staphylococcus aureus bacteraemia and endocarditis, but also includes some data on infections due to Enterococcus spp., especially if vancomycin-resistant. The emergence of resistance in a minority of patients on current dose regimens may mean that trials have to be repeated with higher doses, or the drug used in a combined therapy where rifampicin may be the best choice. In general, equivalence to comparator antibiotic regimens and a correlation for in vitro and in vivo findings have been demonstrated, but there are important gaps in the clinical data including a comparative equivalence trial in streptococcal and enterococcal endocarditis. Clinical benefit might be anticipated, but has not been proved, over aminoglycoside-containing regimens, and economic assessments are critical in the decision as to when and how daptomycin is deployed.

Serum angiotensin-converting enzyme and frequency of severe hypoglycaemia in Type 1 diabetes: does a relationship exist?

AIMS

An association has been described between elevated serum angiotensin-converting enzyme (ACE) and an increased risk of severe hypoglycaemia (SH). To ascertain whether this reported association could be replicated in a different country, it was re-examined in 300 individuals with Type 1 diabetes.

METHODS

People with Type 1 diabetes, none of whom was taking renin-angiotensin system blocking drugs, were recruited. Participants recorded the frequency with which they had experienced SH. Glycated haemoglobin (HbA(1c)) and serum ACE were measured. The difference in the incidence of SH between different quartiles of ACE activity and the relationship between serum ACE and SH were examined using non-parametric statistical tests and a negative binomial model.

RESULTS

Data were obtained from 300 patients [158 male; HbA(1c) median (range) 8.2% (5.2-12.8%), median age 36 years (16-88); duration of diabetes 14.5 years (2-49)]. The incidence of SH was 0.93 episodes per patient year. The mean incidence of SH in the top and bottom quartiles of ACE activity was 0.5 and 1.7 episodes per patient year, respectively, but this difference was not statistically significant (P = 0.075). Spearman's test showed a very weak, although statistically significant, association between serum ACE level and SH incidence (r = 0.115, P = 0.047). The binomial model also showed a statistically significant (P = 0.002), but clinically weak, relationship between serum ACE and SH.

CONCLUSIONS

The present survey showed a weak relationship between serum ACE and the frequency of SH, the clinical relevance of which is unclear. This limits the proposed role for serum ACE as an index of risk for SH.

Introducing estimated glomerular filtration rate (eGFR) into clinical practice in the UK: implications for the use of metformin

AIMS

The reporting of estimated glomerular filtration rate (eGFR) will identify people with diabetes who have previously undiagnosed renal impairment. Our current guideline recommends discontinuation of metformin when serum creatinine > 150 micromol/l. We examined the implications of replacing this with a criterion based on eGFR.

METHODS

The Lothian diabetes register was used to identify patients with Type 2 diabetes for whom age, sex and creatinine measurements within the last 15 months were available. eGFR was calculated using the abbreviated Modification of Diet in Renal Disease (MDRD) equation.

RESULTS

Of 19,981 patients with Type 2 diabetes, 11,297 were taking metformin in accordance with our current guideline. Of these, 9259 (82.0%) had at least stage 2 renal impairment (eGFR < 90 ml/min per 1.73 m(2)) and 2880 (25.5%) had at least stage 3 renal impairment (eGFR < 60 ml/min per 1.73 m(2)). Changing to an eGFR threshold of 36 ml/min per 1.73 m(2) would have a neutral effect on the number of patients eligible for metformin therapy and would permit its use in patients with creatinine concentrations as high as 179 micromol/l. An eGFR threshold of 40 ml/min per 1.73 m(2) would result in 312 (2.8%) patients discontinuing metformin and would permit metformin to be used with creatinine concentrations as high as 163 micromol/l.

CONCLUSIONS

The introduction of eGFR reporting could have a major effect on prescription of metformin. A threshold eGFR of 36-40 ml/min per 1.73 m(2) is approximately consistent with our current practice. If our current practice is considered safe, this would be a useful recommendation.

The effects of acute hypoglycaemia on memory acquisition and recall and prospective memory in type 1 diabetes

AIMS/HYPOTHESIS

Global memory performance is impaired during acute hypoglycaemia. This study assessed whether moderate hypoglycaemia disrupts learning and recall in isolation, and utilised a novel test of prospective memory which may better reflect the role of memory in daily life than conventional tests.

SUBJECTS AND METHODS

Thirty-six subjects with type 1 diabetes participated, 20 with normal hypoglycaemia awareness (NHA) and 16 with impaired hypoglycaemia awareness (IHA). Each underwent a hypoglycaemic clamp with target blood glucose 2.5 mmol/l. Prior to hypoglycaemia, subjects attempted to memorise instructions for a prospective memory task, and recall was assessed during hypoglycaemia. Subjects then completed the learning and immediate recall stages of three conventional memory tasks (word recall, story recall, visual recall) during hypoglycaemia. Euglycaemia was restored and delayed memory for the conventional tasks was tested. The same procedures were completed in euglycaemic control studies (blood glucose 4.5 mmol/l).

RESULTS

Hypoglycaemia impaired performance significantly on the prospective memory task (p = 0.004). Hypoglycaemia also significantly impaired both immediate and delayed recall for the word and story recall tasks (p < 0.01 in each case). There was no significant deterioration of performance on the visual memory task. The effect of hypoglycaemia did not differ significantly between subjects with NHA and IHA.

CONCLUSIONS/INTERPRETATION

Impaired performance on the prospective memory task during hypoglycaemia demonstrates that recall is disrupted by hypoglycaemia. Impaired performance on the conventional memory tasks demonstrates that learning is also disrupted by hypoglycaemia. Results of the prospective memory task support the relevance of these findings to the everyday lives of people with diabetes.

Molecular characterization of plasmids encoding CTX-M-15 -lactamases from Escherichia coli strains in the United Kingdom

OBJECTIVES

The UK, like other countries worldwide, has a growing problem with CTX-M beta-lactamase-producing Escherichia coli. Five major clonally related strains have been identified among CTX-M-15 producers. We characterize here the plasmids from clonal strains A and D.

METHODS

Plasmids were extracted and transformed into E. coli DH5alpha; conjugative mating was attempted on agar. MICs were determined by agar dilution. beta-Lactamases were typed by isoelectric focusing; antibiotic resistance genes and integrons were identified by PCR and sequenced. Plasmid incompatibility groups were determined by replicon PCR.

RESULTS

bla(CTX-M-15) was carried by a 150 kb plasmid in strain A and a 70 kb plasmid in strain D. Conjugative transfer of cefotaxime resistance was only achieved from strain D; plasmids from both strains were transferred by transformation. The plasmid from strain A additionally carried bla(TEM-1) (variably), bla(OXA-1), aac(6')-Ib-cr and tet(A), as well as a class 1 integron with the gene cassettes aadA5 and dfr(17); the plasmid from strain D carried bla(TEM-1) consistently, also bla(OXA-1), aac(6')-Ib-cr, aac3-IIa and tet(A). Both plasmids belonged to incompatibility group FII.

CONCLUSIONS

bla(CTX-M-15) was plasmid-mediated in both strains A and D and was linked to other antibiotic resistance genes including aac(6')-Ib-cr, which encodes an acetyltransferase, not previously found in Europe, acting on both aminoglycosides and some fluoroquinolones. Although the plasmids from the two strains differed in size, both were related and conferred similar multi-drug resistance phenotypes, suggesting that they may share a similar genetic scaffold. Both shared features with plasmids encoding CTX-M-15 beta-lactamases in E. coli from Canada and India.

The impact of a gluten-free diet on adults with coeliac disease: results of a national survey

OBJECTIVE We sought to evaluate the impact of the gluten-free diet on the 5,240 members of the Canadian Celiac Association (CCA). Data are presented on 2,681 adults (>or=16 years) with biopsy-proven celiac disease (CD).

METHODS

A mail-out survey was used. Quality of life was evaluated using the 'SF12', and celiac-specific questions.

RESULTS

Mean age was 56 years, mean age at diagnosis was 45 years, and 75% were female. The 'SF12' summary scores were similar to normative Canadian data, but were significantly lower for females and newly diagnosed patients. Respondents reported: following a gluten-free (GF) diet (90%), improvement on the diet (83%), and difficulties following the diet (44%), which included: determining if foods were GF (85%), finding GF foods in stores (83%), avoiding restaurants (79%), and avoiding travel (38%). Most common reactions to consumed gluten (among 73%) included pain, diarrhea, bloating, fatigue, nausea, and headache. Excellent information on CD and its treatment was provided by the CCA (64%), gastroenterologists (28%), dietitians (26%) and family doctor (12%).

CONCLUSIONS

Quality of life in those with CD could be increased with early diagnosis, increased availability of gluten-free foods, improved food labelling, and better dietary instruction. Education of physicians and dietitians about CD and its treatment is essential.

Guidelines for the prophylaxis and treatment of methicillin-resistant Staphylococcus aureus (MRSA) infections in the UK

These evidence-based guidelines have been produced after a literature review of the treatment and prophylaxis of methicillin-resistant Staphylococcus aureus (MRSA) infection. The guidelines were further informed by antibiotic susceptibility data on MRSA from the UK. Recommendations are given for the treatment of common infections caused by MRSA, elimination of MRSA from carriage sites and prophylaxis of surgical site infection. There are several antibiotics currently available that are suitable for use in the management of this problem and potentially useful new agents are continuing to emerge.

Pubertal stage and hypoglycaemia counterregulation in type 1 diabetes

AIMS

To compare physiological and autonomic responses to acute hypoglycaemia in diabetic children in pre-, mid-, and post-pubertal stages of development.

METHODS

Twenty seven children (8 pre-pubertal, 7 mid-pubertal, 12 post-pubertal) with type 1 diabetes were studied. Hypoglycaemia was induced by insulin infusion until an autonomic reaction (R) was identified. Counterregulatory hormone levels were measured at baseline, R, R+15, and R+30 minutes. Haemodynamic changes and sweat production were measured.

RESULTS

The mean blood glucose level at R was lower in pre-pubertal than mid-pubertal children (2.0 v 2.5 mmol/l), and was positively correlated with HbA1c. Glucagon and noradrenaline responses to hypoglycaemia were minimal in all children. A brisk increase in pancreatic polypeptide (PP) concentration only occurred in post-pubertal children. Only two children showed a sweating response to hypoglycaemia.

CONCLUSIONS

The blood glucose level at which sympatho-adrenal responses to hypoglycaemia were activated was associated with glycaemic control, and varied with pubertal stage. As in adults, the glucagon response to hypoglycaemia was deficient within a few years of developing diabetes. However, sweating and secretion of PP in response to hypoglycaemia did not occur until after puberty, indicating some qualitative differences from adults.

Community and hospital spread of Escherichia coli producing CTX-M extended-spectrum β-lactamases in the UK

OBJECTIVES

During 2003, the Health Protection Agency's Antibiotic Resistance Monitoring and Reference Laboratory began to receive isolates of Escherichia coli for confirmation of extended-spectrum beta-lactamase production with a phenotype implying a CTX-M-type beta-lactamase, i.e. MICs of cefotaxime > or = 8-fold higher than MICs of ceftazidime. Many were referred as being from community patients. We examined 291 CTX-M-producing isolates from the UK and investigated the genetic basis of their phenotype.

METHODS

PCR was used to detect alleles encoding CTX-M enzymes and to assign these to their blaCTX-M phylogenetic groups. Selected alleles were sequenced. Producers were compared by analysis of banding patterns generated by pulsed-field gel electrophoresis of XbaI-digested genomic DNA. MICs were determined by an agar dilution method or by Etest.

RESULTS

Of 291 CTX-M-producing E. coli isolates studied from 42 UK centres, 70 (24%) were reportedly from community patients, many of whom had only limited recent hospital contact. Community isolates were referred by 12 centres. Two hundred and seventy-nine (95.9%) producers contained genes encoding group 1 CTX-M enzymes and 12 contained blaCTX-M-9-like alleles. An epidemic CTX-M-15-producing strain was identified, with 110 community and inpatient isolates referred from six centres. Representatives of four other major strains also produced CTX-M-15, as did several sporadic isolates examined. Most producers were multi-resistant to fluoroquinolones, trimethoprim, tetracycline and aminoglycosides as well as to non-carbapenem beta-lactams.

CONCLUSIONS

CTX-M-producing E. coli are a rapidly developing problem in the UK, with CTX-M-15 particularly common. The diversity of producers and geographical scatter of referring laboratories indicates wide dissemination of blaCTX-M genes. Because of the public health implications, including for the treatment of community-acquired urinary tract infections, the spread of these strains--and CTX-M-15 beta-lactamase in particular--merits close monitoring.

Hypoglycaemia and driving in people with insulin-treated diabetes: adherence to recommendations for avoidance

BACKGROUND

Hypoglycaemia impairs driving performance, so drivers with insulin-treated diabetes should try to avoid hypoglycaemia when driving, and treat it effectively if it occurs. It is not known how many insulin-treated drivers are familiar with, or adhere to, recommended safe practice.

METHODS

We surveyed a representative sample of 202 current drivers with insulin-treated diabetes (115 with Type 1 diabetes), using a structured questionnaire. Data were obtained on driving history, estimated frequency of hypoglycaemia, and measures taken to avoid and treat hypoglycaemia when driving.

RESULTS

The licensing authority (DVLA) and motor insurance company had been informed by almost all participants. Sixty-four participants (31.7%) had experienced hypoglycaemia while driving, and 27 (13.4%) reported that this had occurred within the preceding year. A minimum blood glucose level of 4.0 mmol/l or higher was considered necessary for driving by 151 drivers (74.8%), and 176 (87.1%) reported always keeping carbohydrate in their vehicle. However, 77 (38.1%) reported never carrying a glucose meter when driving, and 121 (59.9%) that they never test blood glucose before driving, or test only if symptomatic of hypoglycaemia. Most participants (89%) would stop driving to treat hypoglycaemia and would not resume driving immediately, although only 28 (13.9%) would wait longer than 30 min. Almost half of participants were failing to observe at least one essential aspect of safe driving.

CONCLUSIONS

Compliance with statutory requirements to inform the licensing authority and motor insurer is good, and drivers' perceptions of the minimum safe blood glucose level for driving are encouraging. However, most drivers rely on symptoms to detect hypoglycaemia while driving, and seldom test blood glucose before driving. Patient education should emphasize the role of blood glucose monitoring in relation to driving, and highlight the potential deterioration in driving performance when blood glucose falls below 4.0 mmol/l.

Comparison of the performance of selenite cystine and mannitol selenite enrichment broths in the isolation of Salmonella spp. from faeces

Over a four-month period, 4,658 routine faecal samples were examined in four laboratories and the isolation rates of Salmonella spp. from mannitol selenite (MS) and selenite cystine (SC) broths plated to xylose lysine desoxycholate agar (XLD) compared. The isolation rate by MS was 1.55% and by SC was 1.48%, a small difference which is not statistically significant. Significantly fewer colonies were selected for supplementary testing from SC than MS (p = 0.029), thus reducing confirmatory work. In laboratories where SC is already used for food and environmental work, an opportunity exists to limit stocked salmonella enrichment broths to SC alone.

A comparison of the performance of commercially available chromogenic agars for the isolation and presumptive identification of organisms from urine

AIMS

To compare four media-UTI medium, BBL CHROMagar, CPS ID2, and Harlequin CLED-using a collection of fully characterised organisms and subsequent "field trial".

METHODS

Seven hundred and eighty seven fully characterised isolates (730 Gram negative bacteria, 47 Gram positive bacteria, and 10 yeasts) were used to test for accuracy of organism identification. To assess isolation rates and ability to detect mixed cultures, 1435 urine samples were cultured in the three best performing chromogenic media (UTI medium, BBL CHROMagar, and CPS ID2) and CLED.

RESULTS

The chromogenic agars differed in their accuracy of identification, with BBL CHROMagar performing best and Harlequin CLED performing least well. Similarly, BBL CHROMagar achieved a higher overall isolation rate than UTI medium and CPS ID2. When mixed growth was defined as greater than two organism types, BBL CHROMagar detected more mixed cultures than did UTI medium and CPS ID2, although the differences were not significant. When mixed growth was defined as greater than one organism type the increased number of mixed growths detected by BBL CHROMagar became significant, largely because of differences in enterococcal isolation rates.

CONCLUSION

The use of BBL CHROMagar, UTI medium, or CPS ID2 chromogenic agar as a replacement for CLED agar would improve the detection rate of contaminated urine samples. Enhanced identification helps to distinguish different species, facilitating the monitoring of bacterial resistance in support of the national antibiotic strategy. BBL CHROMagar gave the highest overall organism recovery rates, greatest ability to detect mixed cultures, and the most accurate identification of organisms.

Effect of incubation temperature on the isolation of thermophilic species of Campylobacter from faeces

Although no large-scale clinical study has been performed, it has been reported that incubation at 37 degrees C gives better isolation rates for all common species of Campylobacter than incubation at 42 degrees C, while also improving the recovery of the more unusual species. In this study, 2,570 faecal samples were examined in four laboratories, using a standardised protocol. Isolation rates of Campylobacter spp. were compared after incubation on modified campylobacter blood-free selective agar at 37 degrees C and 42 degrees C. Campylobacter spp. isolates were made from 185 samples (7.2%); 25 were recovered only at 42 degrees C and three only at 37 degrees C (p < 0.001). There were significantly more colonies at 42 degrees C (p = 0.001). Competing flora were heavier at 37 degrees C, but this did not account for the difference in isolation rates or quantity of growth. It is recommended that cultures for Campylobacter spp. be routinely incubated at 42 degrees C. More specific techniques are required to seek for fastidious campylobacters.

Comparison of the performance of lactose and mannitol selenite enriched broths, subcultured to DCA and XLD agars, in the isolation of Salmonella spp. from faeces

Selenite-based enrichment broths using either lactose or mannitol as a carbohydrate source are generally used as selective enrichment media for the isolation of Salmonella spp. from human faeces in the UK, but few studies have compared the relative efficacy of the available formulations. A variety of solid media is used for the routine subculture from these selective broths, but similarly we have been unable to find published evidence as to which medium performs best. Four thousand and nineteen faecal samples were examined in four laboratories and the isolation rates of Salmonella spp. from lactose (LS) or mannitol selenite (MS) broths, plated onto either xylose lysine desoxycholate agar (XLD) or desoxycholate citrate agar (DCA) were compared. MS performed significantly better than LS (p = 0.02), recovering 95 salmonellae compared with 87. No significant difference in isolation rates was found between XLD and DCA, although colonial appearances of suspected salmonellae on XLD were much more specific, resulting in significantly fewer colonies having to be selected for supplementary testing (p < 0.001) and so reducing confirmatory work. An opportunity exists to simplify holdings of media by choosing to use the MS/XLD combination.

A comparison of the performance of cystine lactose electrolyte deficient (CLED) agar with Oxoid chromogenic urinary tract infection (CUTI) medium for the isolation and presumptive identification of organisms from urine

AIMS

As part of the UK antimicrobial resistance strategy and action plan, the Public Health Laboratory Service (PHLS) is required to collect antibiotic susceptibility data so that resistance trends and patterns can be monitored. Most laboratories report urine Gram negative isolates, as "coliforms" according to morphological appearance, but without an acceptable identification system the antimicrobial surveillance data will be meaningless. Commercially available identification systems tend to be expensive and time consuming. Chromogenic agars, which claim to improve the detection of mixed cultures and identification of organisms from urine, have now become available and may provide a cost effective alternative. The primary aim of this study was to compare the performance of cystine lactose electrolyte deficient (CLED) agar with a chromogenic agar (Oxoid urinary tract infection medium; CUTI) in terms of isolation rates and ability to detect mixed cultures. Secondary aims were to evaluate the correlation of "presumptive" identification of isolates from chromogenic media with that of two commercial identification systems and to appraise the sensitivity of the semiquantitative loop and filter paper strip culture techniques.

METHOD

One thousand, four hundred and sixty six urine samples were examined in four laboratories using the semiquantitative culture methods of 1 microl loop and filter paper strip. The degree of accuracy of organism identification was measured by comparing the presumptive identification using colony colour supplemented with simple bench tests, with identification obtained from two more complex commercial systems.

RESULTS

There was no significant difference between the performance of the loop and filter paper strip methods on the CLED agar, but the CUTI agar performed significantly better than the CLED agar for the detection of significant isolates and mixed cultures. This difference was greater using the loop method. Identification of the organisms using the commercial systems gave > 99% agreement and was therefore considered suitable as a standard against which to compare the presumptive CUTI identification. Using the manufacturer's colony colour criteria in combination with a bench indole test, the CUTI medium was 99% specific for Escherichia coli, although this was reduced to 97% if the indole test was omitted. Citrobacter spp were the most commonly misidentified organisms, giving false presumptive identification as E coli. By testing oxidase activity to differentiate Pseudomonas spp and the absence of indole production to support the identification of Proteus mirabilis, the CUTI medium provided a suitable identification for 86.8% of Gram negative isolates. The remaining 13.2% would require further identification.

CONCLUSION

CUTI medium improves the detection of mixed cultures, thereby improving the reliability of reporting of significant isolates when compared with CLED agar. When supplemented with simple bench tests it provides an identification system capable of speciating 86.8% of Gram negative isolates and providing a valuable cost effective mechanism for antimicrobial resistance surveillance.

An evaluation of the performance of XLD, DCA, MLCB, and ABC agars as direct plating media for the isolation of Salmonella enterica from faeces

AIMS

To compare the performance of four media, singly and in combination, as direct plating media for the isolation of Salmonella enterica from human faeces.

METHODS

Two thousand four hundred and nine routine, faecal samples received by four laboratories were inoculated on to xylose lysine desoxycholate (XLD), desoxycholate citrate (DCA), mannitol lysine crystal violet brilliant green (MLCB), and alpha-beta chromogenic (ABC) agars using standardised protocols, reagents, and data collection. Isolates of presumptive salmonellae were identified using standard laboratory techniques and the results were analysed statistically.

RESULTS

Direct plating recovered 46 of the 60 possible isolates of Salmonella spp recovered via enrichment broth. No isolates were recovered from direct plating that were not recovered via selenite enrichment. MLCB gave the highest isolation rate individually (84.8%) and amounts of competing flora (CF) did not affect the recognition of colonies. ABC proved highly specific, but insensitive, and isolation rates were adversely affected by any amount of CF. Isolation rates from XLD and DCA were only affected when the CF load was heavy. DCA was least specific, with only 9.01% of picks positive and greatest number of confirmatory tests. XLD and MLCB, in combination, gave the highest isolation rate.

CONCLUSIONS

Where the earlier results of direct plating may be advantageous, XLD and MLCB provide the optimal combination. For non-typhi salmonellae, MLCB is the best, single direct plating medium. For routine diagnostic work, XLD is most effective.

A comparison of the isolation rates of Salmonella and thermophilic Campylobacter species after direct inoculation of media with a dilute faecal suspension and undiluted faecal material

Regardless of media used, dilution of faecal samples before direct plating may improve isolation rates and reduce subcultures by freeing organisms from the faecal mass and diminishing competing flora. Despite the routine use of dilution in many laboratories, it has never been established properly whether direct or dilute inocula should be used in primary plating of faeces. A total of 3764 faecal samples was examined in four laboratories with a standardised methodology. The isolation rates, competing flora and confirmatory work performed for Salmonella spp. and Campylobacter spp. from primary plating media with a dilute faecal inoculum were compared with those after direct inoculation of faecal material. Inoculum effects on the isolation of Shigella spp. could not be assessed as only one isolate occurred during the study period. The overall isolation rates of both major enteric pathogens were unaffected by the inoculum. However, significantly fewer wasted subcultures were recorded with a dilute inoculum for Campylobacter spp., and competing florawas reduced in all cases without diluting out small numbers of the pathogen.

A comparison of the performance of bacitracin-incorporated chocolate blood agar with chocolate blood agar plus a bacitracin disk in the isolation of Haemophilus influenzae from sputum

The lack of selectivity of chocolated blood agar (CBA), routinely used for the isolation of Haemophilus influenzae, may lead to masking of the growth of H. influenzae due to overgrowth of competing flora. Bacitracin can be used as a selective agent, either incorporated into the medium or applied to the medium in a filter paper. However, neither method has been evaluated or compared in a large study. Sputum samples (1990) were examined in four laboratories and the isolation rates of H. influenzae on chocolated blood agar with bacitracin added to the medium (BCA) and chocolated blood agar (CBA) with a bacitracin disk were compared. A plain blood agar plate was also inoculated to facilitate the isolation of Streptococcus pneumoniae so that its effects on the isolation of H. influenzae could be assessed. No significant difference was found between the isolation rates of H. influenzae on BCA and CBA with a bacitracin disk, although competing flora was greatly reduced and quantity of growth of H. influenzae increased on BCA. The presence of S. pneumoniae did not affect the isolation of H. influenzae in this study.

A comparison of blood agar supplemented with NAD with plain blood agar and chocolated blood agar in the isolation of Streptococcus pneumoniae and Haemophilus influenzae from sputum. Bacterial Methods Evaluation Group

Streptococcus pneumoniae grows well and generally exhibits typical morphology on Columbia blood agar, whereas Haemophilus influenzae requires a more complex medium to meet its growth requirements - usually chocolated blood agar - on which S. pneumoniae is less easily recognisable. Therefore, a single medium that produces typical morphology of S. pneumoniae and facilitates the growth of H. influenzae would have considerable potential advantages. It has been claimed that blood agar supplemented with nicotinamide adenine dinucleotide (NAD) is such a medium. However, despite its routine use in several large diagnostic laboratories its performance has never been properly evaluated. In the present study, 1724 sputum samples were examined in four laboratories. The isolation rates of H. influenzae and S. pneumoniae on NAD-supplemented blood agar (SBA) were compared with those on a two-plate combination of plain blood (BA) and chocolated blood agar (CBA). The two-plate combination performed significantly better for both organisms; isolation rates for H. influenzae were increased from 8.16% on SBA to 11.07% on BA plus CBA and for S. pneumoniae from 4.18% to 4.68%. Isolation rates were also compared after incubation for 24 and 48 h. With the two-plate combination, isolation rates for H. influenzae and S. pneumoniae were increased by 0.98% and 0.16%, respectively, and for SBA by 0.57% and 0.32% after 48 h. However, despite this increase, SBA still performed less well than the two-plate combination.

NSAID injury to the small intestine

PURPOSE

To identify the clinical and radiologic findings in patients with diaphragm-like strictures in the small bowel.

PATIENTS AND METHODS

We reviewed the histories, radiologic findings, and pathologic findings in two men and two women, all in their sixties, with a history of long-term nonsteroidal antiinflammatory drug (NSAID) or aspirin (ASA) usage and one or more radiologically demonstrated diaphragm-like strictures in the small bowel.

RESULTS

Two patients had long histories of NSAID usage, and two of ASA usage. One NSAID user had a long segment of jejunal involvement, and the other three had short segments of duodenal involvement. The ASA users presented with symptoms of esophageal disease, the small bowel lesions were unexpected, and ASA usage was not initially elicited. In one NSAID user and one ASA user, broader strictures with humps rather than diaphragms were also seen producing a lifesaver-like or bagel-like configuration.

CONCLUSIONS

Multiple diaphragm-like strictures can occur in NSAID injury and are pathognomonic except in the rare patient with ulcerative enteritis complicating celiac disease. Single or few diaphragm-like strictures can occur in NSAID injury and peptic ulceration. ASA should be considered an NSAID with regard to small-bowel toxicity. A careful medication history is required when an unexplained small bowel abnormality is seen radiologically, and a dedicated small bowel examination is required when NSAID injury is suspected.

Guidelines for the investigation of invasive fungal infections in haematological malignancy and solid organ transplantation. British Society for Medical Mycology

Invasive fungal infections are increasing in incidence and now affect as many as 50% of neutropenic/bone marrow transplant patients and 5 to 20% of solid organ transplant recipients. Unfortunately, many of the diagnostic tests available have a low sensitivity. The guidelines presented here have been produced by a working party of the British Society for Medical Mycology in an attempt to optimise the use of these tests. The yield of fungi from blood cultures can be increased by ensuring that at least 20 ml of blood are taken for aerobic culture, by using more than one method of blood culture, and by employing terminal subculture if continuous monitoring systems are used with a five-day incubation protocol. Skin lesions in febrile neutropenic patients should be biopsied and cultured for fungi. The detection of galactomannan in blood or urine is of value in diagnosing invasive aspergillosis only if tests are performed at least twice weekly in high-risk patients. Antigen detection tests for invasive candidiasis are less valuable. Computed tomography scanning is particularly valuable in diagnosing invasive pulmonary fungal infection when the chest radiograph is negative or shows only minimal changes. Bronchoalveolar lavage is most useful in patients with diffuse changes on computed tomography scan. The major advances in the diagnosis of invasive fungal infection in patients with haematological malignancy or solid organ transplantation have been in the use of imaging techniques, rather than in the development of new mycological methods in the routine laboratory.

Pancreaticoduodenal tuberculosis simulating metastatic ovarian carcinoma

A patient from Thailand presented with symptoms suggestive of peptic ulceration. Radiology showed an ulcerated duodenal stricture, a pancreaticoduodenal mass and extensive retroperitoneal lymphadenopathy suggestive of metastatic carcinoma. Tuberculosis was diagnosed only at laparotomy. The incidence of tuberculosis is increasing, and alimentary tuberculosis should be considered in patients from populations at risk presenting with obscure abdominal complaints or unexplained radiologic findings.

Susceptibility testing of Haemophilus influenzae--an international collaborative study in quality assessment

In order to compare the prevalence of antibiotic resistance in different geographical areas, it is necessary to ensure that agreement is achieved between laboratories on the assignment of strains to 'susceptible' and 'resistant' categories. An international quality assessment study, involving 15 laboratories in eight countries, was performed to investigate the standard of performance of the susceptibility testing of Haemophilus influenzae. One hundred and fifty strains of H. influenzae were distributed from the London Hospital Medical College (LHMC) to all laboratories who were asked to test the susceptibility of the strains to ampicillin, chloramphenicol, tetracycline, trimethoprim, cephalosporins and ciprofloxacin. Laboratories were also asked to provide the details of methodology to test the susceptibility. Significant discrepancy between the LHMC and the participating laboratories appeared in the detection of resistance to ampicillin (especially beta-lactamase-negative strains resistant to ampicillin) as well as the assignment of susceptibility and resistance to chloramphenicol, tetracycline and trimethoprim. Often these reflected the use of inappropriate breakpoints which led to erroneous assignment of susceptibility. Other variations including disc content, medium and supplement, inoculum as well as failure to measure zone sizes properly also led to some repeating anomalies.

Single-beam diode-laser technique for optical path-length measurements

A simple single-beam technique employing radio-frequency modulation of a tunable diode laser with homodyne demodulation is demonstrated as a means of measuring optical path lengths. This technique offers a straightforward method for determining path lengths traversed through optical multipass cells or performing optical range-finding over short (i.e., tens of meters) standoff distances. The radio-frequency phase-sensitive nature of the technique permits narrow-band detection and high signal-to-noise ratios, even when range-finding measurements are made with range resolutions of «1 m. This compares favorably with traditional short-pulse, wide-bandwidth optical range finders.

Optimum detection of multiple vapor materials with frequency-agile lidar

Differential absorption lidar (DIAL) is a well-established technology for estimating the concentration and its path integral CL of vapor materials using two closely spaced wavelengths. The recent development of frequency-agile lasers (FAL's) with as many as 60 wavelengths that can be rapidly scanned motivates the need for detection and estimation algorithms that are optimal for lidar employing these new sources. I derive detection and multimaterial CL estimation algorithms for FAL applications using the likelihood ratio test methodology of multivariate statistical inference theory. Three model sets of assumptions are considered with regard to the spectral properties of the backscatter from either topographic or aerosol targets. The calculations are illustrated through both simulated and actual lidar data.

Fungal infections: a survey of laboratory services for diagnosis and treatment

A questionnaire on the services provided and the methods used for the diagnosis of fungal infections and for the support of antifungal chemotherapy was sent to members of the British Society for Medical Mycology (BSMM) and the British Society for Antimicrobial Chemotherapy (BSAC). Ninety-five responses from general microbiology laboratories in the United Kingdom were analysed, and we compared services provided by laboratories that serve a transplant unit with those offered by other laboratories. We estimate that about 150 cases of cryptococcosis, 500 to 600 of candidaemia, and 300 to 400 of invasive aspergillosis are identified by laboratories in the United Kingdom (UK) each year. The clinical laboratories are aware of the importance of fungal infection, but rely heavily on reference services. In some laboratories, however, the degree of investigation of specimens and the procedures in use are inadequate for diagnosing systemic mycoses and determining the susceptibility of isolates to antifungal agents. The balance between reference and local services requires attention and external quality assurance needs to be applied effectively. In addition, effective methods for the diagnosis of systemic mycoses, and reliable and practicable methods for determining the susceptibility of isolates to antifungal agents, are needed urgently.

Antifungal drug susceptibility testing. Working Party of the British Society for Antimicrobial chemotherapy

This article describes the current situation with regard to intrinsic and acquired resistance to antifungal compounds and progress with the development of standardized methods of susceptibility testing for amphotericin B, flucytosine, and the azoles. Recommendations for testing of isolates from patients destined to receive antifungal drug treatment, or in whom therapeutic failure or relapse is suspected, are presented.

Myeloid progenitor cell regulatory effects of vascular endothelial cell growth factor

Vascular endothelial cell growth factor (VEGF) is a ligand for the tyrosine kinase receptor Flk-1/KDR and Flt1 and is considered to be an endothelial cell specific mitogen that plays an important role in angiogenesis. Since Flk-1 mRNA has been detected in primitive and more mature hematopoietic cells, recombinant human VEGF was evaluated for its influence on hematopoiesis, which was assayed as in vitro colony formation by myeloid progenitor cells from human bone marrow. VEGF enhanced colony formation by mature subsets of granulocyte-macrophage and erythroid progenitor cells that had been stimulated with a colony stimulating factor. In contrast, VEGF inhibited colony formation by more immature subsets of granulocyte-macrophage, erythroid and multipotential progenitor cells synergistically stimulated to proliferate with a colony stimulating factor and either steel factor or the ligand for the Flt-3 receptor tyrosine kinase. VEGF produced effects similar to those given above on purified CD34 progenitor cells from bone marrow and VEGF effects were neutralized by VEGF antibodies. However, when assessed for effects on single sorted CD34 cells, VEGF only enhanced or suppressed colony formation by granulocyte-macrophage progenitor cells and the amplitude of the response was less than that observed when populations of these cells were tested. In the single cell assays, VEGF had no effect on colony formation by erythroid or multipotential progenitors. These results suggest that the effects of VEGF, which were not species specific, are mediated by both direct and indirect actions on the progenitors and thereby identify new activities for this important factor.

Gastrocolic fistula secondary to primary gastric lymphoma

Gastrocolic fistula in primary non-Hodgkin's lymphoma (NHL) of the stomach is rare; in a review of the literature we found only four cases, all in association with disseminated (stage IV) disease. We describe the first case of a gastrocolic fistula in a patient with stage IE lymphoma. The diagnosis was suggested by feculent vomiting, and the fistula was located using barium enema and CT scan. Therapy consisted of local resection followed by combination chemotherapy.

Eosinophilic pleural effusion associated with recovery from viral hepatitis A

Pleural effusion represents a rare complication of acute viral hepatitis; only one case has been reported in association with type A viral hepatitis. We report here the second case, in a 24-year-old female nurse who developed a large symptomatic right pleural effusion 9 weeks after the onset of fulminant type A viral hepatitis. Ascites and edema did not develop. The effusion, exudative with an eosinophilic cellular predominance, manifested 2 weeks following recovery from viral hepatitis and resolved spontaneously. Other causes were excluded by investigation. This is the first report of a pleural effusion complicating viral hepatitis during the recovery period; moreover, it is the first case associated with pleural fluid eosinophilia.

Kalman filtering of tunable diode laser spectrometer absorbance measurements

A recursive Kalman time-series filter was applied to absorbance measurements obtained with a tunable diode laser spectrometer. The spectrometer uses frequency modulation spectroscopy and a nearinfrared diode laser operating at 1.604 µm to monitor the CO(2)-vapor concentration in a 30-cm absorption cell. The Kalman filter enhanced the signal-to-noise ratio of the spectrometer by an order of magnitude when an absorbance of 6 × 10(-5) was monitored.

Experimental gene therapy of human colon cancer

BACKGROUND

Gastrin regulates growth of human colon cancer cells by activation of the cyclic adenosine monophosphate (cAMP)-dependent protein kinase A (PKA). Gastrin and 8-Br-cAMP, a membrane-permeable cAMP analog, inhibit growth of HCT116 cells; both stimulate growth of LoVo cells. This dual effect on growth may be explained by relative amounts of the regulatory subunit (RI alpha or RII beta) of PKA within the cancer cells. Antisense oligodeoxynucleotides (ASO) to either RI alpha or RII beta inhibit protein translation of the target mRNA by sequence-specific binding; subsequently, cellular PKA content and the cAMP-mediated growth may be altered. We determined whether ASO to either the RI alpha or RII beta subunit altered the cAMP-mediated growth of HCT116 and LoVo human colon cancer cells.

METHODS

HCT116 cells were treated with RII beta ASO (15 mumol/L, 4 days) and then treated with 8-Br-cAMP (25 mumol/L); tritiated thymidine incorporation was measured after 24 hours, and the cell number was determined on alternate days. Protein and mRNA levels of the RII beta subunit were determined by Western and Northern blotting, respectively. Similar studies with an ASO against the RI alpha subunit were performed on LoVo cells.

RESULTS

RII beta ASO reversed the cAMP-mediated inhibition of growth of HCT116 cells, and RII beta ASO decreased the protein level of the RII beta subunit. RII beta ASO did not alter the basal growth of HCT116 cells. RI alpha ASO reversed the cAMP-mediated stimulation of growth of LoVo cells.

CONCLUSIONS

The regulatory subunits of PKA are potential targets to alter growth of human colon cancer cells. Gene therapy directed to alter specific steps in signal transduction pathways may provide new therapeutic strategies.

Development of an internal quality assessment scheme in a clinical bacteriology laboratory

AIM

To develop an internal quality assessment (IQA) scheme in a clinical bacteriology laboratory.

METHODS

Over 24 months, 1230 diagnostic specimens, representing 0.42% of laboratory workload, were anonymised and resubmitted for analysis. Six hundred and twenty one (48.7%) of these gave positive culture results; 44 fecal and upper respiratory specimens were "spiked" (artificially inoculated) to increase the proportion of positive samples.

RESULTS

Discrepancies between IQA and clinical sample results occurred in 188 cases (14.8%): 76.6% of these were in culture results, 13.3% in microscopy performance, and 10.1% in clerical recording. The culture discrepancy rate for each positive sample was lowest for wound (17.5%) and urine (18.1%) specimens, and highest for faeces (34.9%) and upper respiratory (37.7%) samples. Discrepancies in several areas responded to staff training and improvement in technical methods.

CONCLUSIONS

An IQA programme of this type assesses the reproducibility of tests within a diagnostic laboratory when analysing common specimen types and organisms. It permits blind assessment of many areas of diagnostic work that are not readily amenable to other quality assurance methods, and it raises the awareness of all staff to the importance of quality in every aspect of specimen and data processing.

Venous intravasation of barium: CT findings

Portal venous barium and air intravasation occurred during an air contrast enema in a man with ulcerative colitis. Abdominal plain radiography and CT subsequently showed increased hepatic density. Computed tomography also showed colonic intramural and pericolic nodal or venous barium, increased splenic density, and pulmonary arterial barium. The patient's course was benign because little barium embolized beyond the liver into the systemic circulation.

Neutropenic enterocolitis associated with Clostridium tertium

A 15 year old boy being treated for relapsed acute lymphoblastic leukaemia developed severe diarrhoea and abdominal pain which worsened despite empirical antibiotic treatment. A right hemicolectomy was performed. The caecum and ascending colon showed changes typical of neutropenic enterocolitis. Clostridium tertium was isolated from faeces, blood cultures, and from the resected gut wall, with no evidence of other organisms capable of causing such a condition. As far as is known, this is the first reported case in which neutropenic enterocolitis has been associated with well documented C tertium infection, an organism previously described as a cause of bacteraemia in neutropenic patients.

Antibodies to meningococcal class 1 outer membrane proteins in South African complement-deficient and complement-sufficient subjects

Inhibition assays were used to investigate human serum antibodies to the meningococcal class 1 outer membrane proteins. We adapted the whole-cell enzyme-linked immunosorbent assay technique to determine the ability of sera to inhibit the binding of murine subtyping monoclonal antibodies. Serum samples from 33 South African subjects with a deficiency in the sixth component of complement as well as serum samples from various groups of complement-sufficient subjects were investigated. Subjects were subdivided according to whether they were (i) convalescent from Neisseria meningitidis infections, (ii) nonconvalescent, or (iii) controls. Preliminary subtyping investigations had shown that P1.2 was present on 36% of meningococcal clinical isolates from Cape Province, South Africa. Assays with the anti-P1.2 antibodies showed the presence of high antibody levels in many deficient sera and moderately elevated levels in some sera from the complement-sufficient convalescent patients. P1.2, P1.4, P1.15, and P1.16 are epitopes situated on loop 4 of the class 1 outer membrane proteins, whereas P1.7 is on loop 1. Inhibition assays showed that human sera that inhibited binding by P1.2 monoclonal antibodies tended to inhibit the other monoclonal antibodies directed to loop 4 epitopes. This suggests that the epitopes recognized by the human antibodies are not exactly the same as the epitopes recognized by the murine monoclonal antibodies and raises the possibility of the importance of other epitopes.