Idiopathic CSF rhinorrhoea presenting with tension pneumocephalus and hemiparesis

A case of non-traumatic/non-iatrogenic CSF rhinorrhoea, presenting with tension pneumocephalus and hemiparesis is described. The possible pathological processes involved in this rare case are discussed. Cases in the literature of idiopathic CSF rhinorrhoea and also those of spontaneous pneumocephalus are reviewed.

Pneumococcal bacteraemia and meningitis in England and Wales, 1993 to 1995

A total of 10,346 blood and 682 cerebrospinal fluid (CSF) isolates of Streptococcus pneumoniae were reported to the PHLS Communicable Disease Surveillance Centre from laboratories in England and Wales from 1 January 1993 to 31 December 1995. This corresponds to a mean annual incidence of 6.7 per 100,000 episodes of bacteraemia and 0.44/100,000 of meningitis. Absolute numbers of pneumococcal bacteraemia were similar to levels reported between 1990 and 1992, but fewer isolates of pneumococci were made from CSF. There was no discernible overall trend between 1993 and 1995, but age specific incidence suggested a slight increase in bacteraemia in older age groups. Estimated case fatality rates were 20% for pneumococcal bacteraemia and 22% for meningitis. The proportion of pneumococcal strains resistant to penicillin and erythromycin rose between 1989 and 1995 from 0.3% to 2.9% and 3.3% to 10.9%, respectively. The persistent threat of invasive pneumococcal infections highlights the need for continuing laboratory surveillance (including serotyping), appropriate use of antibiotics, and immunisation of groups at risk. The development of conjugate vaccines offers new prospects for prevention.

Plasmid analysis

Bacterial plasmids are extra-chromosomal, covalently-closed circular (CCC) molecules of DNA that are capable of autonomous replication (1). Plasmids may contain genes for a variety of phenotypic traits, such as antibiotic resistance, virulence, or metabolic activities, although some plasmids comprise genes conferring no detectable phenotype and are said to be "cryptic " Some plasmids (referred to as selftransferable or conjugative plasmids) have the ability to transfer copies of themselves to other bacterial strains or species; this trait is encoded by tra genes, In addition, some other plasmids are incapable of selftransfer, but are able to utilize the tra functions of cojugative plasmids present in the same bacterial cell to ensure that they are also passed to other strains and species; such plasmids are said to be mobilized.

Visualisation in the SPROUT molecular design program

SPROUT is an interactive computer system for structure based molecular design. The system consists of several modules that address the different subproblems of structure based drug design. This paper describes the visualisation techniques applied in the program: the display of the novel (geometric region) representation of the interaction sites and the molecular surface display based on a 3D grid representation of the cavity. The hydrogen bonding regions are represented by set operations (subtraction and intersection) of simple spherical and conical 3D objects (with given radii and opening angle) Some complex hydrogen bonding regions are represented by intersections of six or more basic objects. A method for calculating a triangular mesh representation (with normal vectors) of the analytical surfaces of the objects, that have sharp edges and corners because of the intersections, is presented in the paper. The geometric parameters of the interaction regions can be changed interactively in which case the surface display is updated real-time. The volume of space that is available for ligand generation (the cavity of the receptor site) is represented on a 3D grid within SPROUT. The surface of the available space is visualised using an algorithm presented in the paper, that generates a polygonial mesh of the grid points. The grid is also used to cut out stericaly forbidden parts of the interaction site regions. The surface of the reduced object is also visualised using further sphere subtractions. The presented algorithms are fast, aplicable in interactive visualisation programs. Result images of the rendering of the surfaces, calculated by the algorithms, are demonstrated on examples taken from applications of SPROUT to practical ligand design problems.

Serogroups/types and antibiotic resistance of referred isolates of Streptococcus pneumoniae: 1993 to 1995

Surveillance of prevalent serogroups/types of Streptococcus pneumoniae and their susceptibility to antimicrobial agents is important for understanding the epidemiology of pneumococcal infections and for guiding empirical treatment. Current vaccines for prevention of pneumococcal infection utilise serotype specific antigens, so knowledge of the prevalence of particular serotypes is relevant to vaccine use and development. Five thousand seven hundred and ninety-six isolates of S. pneumoniae from separate patients were serogrouped or serotyped by the Streptococcus and Diphtheria Reference Unit between 1993 and 1995. Antibiotic susceptibility testing was carried out by the Antibiotic Reference Unit on 3821 (65.9%) of these isolates. A total of 40 distinct serogroups/types, together with a small number of non-typable isolates, were noted over the three year period. The same five serogroups/types (6, 9, 14, 19, and 23) occurred most commonly in each year of the study, not only in the total population of isolates studied, but also in isolates obtained from blood or cerebrospinal fluid, and among isolates with antibiotic resistance. Ninety-six per cent of the isolates belonged to serogroups/types included in the currently available 23-valent capsular polysaccharide pneumococcal vaccine; the conjugate petna-, hepta-, and nonavalent vaccines covered 51%, 75%, and 80% of isolates respectively. The nonavalent vaccine offers the most promise as 74% of all blood and cerebrospinal fluid isolates and 90% of antibiotic resistant isolates belonged to serogroups or types included in this formulation.

Resistance to methicillin and other antibiotics in isolates of Staphylococcus aureus from blood and cerebrospinal fluid, England and Wales, 1989-95

BACKGROUND

Methicillin-resistant Staphylococcus aureus (MRSA) strains are colonising hospital patients in most areas of England and Wales, UK. The extent to which they cause invasive infection can be gauged from their presence in isolates from blood or cerebrospinal fluid.

METHODS

About 200 clinical laboratories reported the results of susceptibility testing of between 4501 and 6370 isolates of S aureus from blood or cerebrospinal fluid in each of the years 1989-95. We assessed the rate of resistance to methicillin and other antibiotics for each of these years.

FINDINGS

Resistance to methicillin was stable at about 1.5% of isolates during 1989-91, but increased thereafter to 13.2% in 1995 (p < 0.001). At the same time there was a significant increase in the percentage of isolates resistant to erythromycin, clindamycin, ciprofloxacin, gentamicin, trimethoprim, and rifampicin (p < 0.001 for each)-resistance characteristics often seen in MRSA. Resistance to benzylpenicillin increased slightly but significantly (p < 0.001); resistance to fusidic acid was stable (p > 0.05); resistance to tetracycline decreased significantly (p < 0.001).

INTERPRETATION

Among cases of S aureus bacteraemia, the proportion due to MRSA has increased significantly. Bacteraemia due to MRSA has a poor prognosis, especially if not treated with suitable antibiotics. Therefore, these findings are important, especially for management of patients and the development of antibiotic policies.

The identification and purification of a novel mammalian DNA ligase

Using a combination of biochemical fractionation and adenylation assays, we have purified a novel 44 kDa protein from human cells which rejoins DNA double-strand breaks. Its rejoining properties and its ability to form an adenylation product with ATP, which can be rapidly dissociated by the presence of DNA breaks, show that this protein is a DNA ligase. As four mammalian DNA ligases have been previously identified we have named this DNA ligase V. Silver staining of the most purified fraction on denaturing polyacrylamide gels reveals a protein doublet of 46/44 kDa of which only the lower band becomes adenylated. Assay of this protein, along with two defined DNA ligases, against DNA templates containing either double and single-strand breaks shows that unlike other DNA ligases, DNA ligase V does not join nicked templates with high efficiency. However, this DNA ligase can join double-strand breaks with a similar efficiency to DNA ligase 1. This result indicates that there may be different types of DNA ligases in mammalian cells which may have specific cellular functions.

Obstructive sleep apnoea syndrome (OSAS) as a complication of carcinoid syndrome treated successfully by hepatic artery embolization

Obstructive sleep apnoea syndrome (OSAS) appears to be an extremely rare complication of carcinoid syndrome and has not yet been reported in the literature. We describe a 75-year-old patient with a history of bronchial carcinoid who besides typical carcinoid syndrome symptoms developed sleep disturbance and day lethargy caused by massive facial and nasal tissue oedema. Sleep apnoea was confirmed by sleep study. Abdominal ultrasound and computed tomography (CT) scan showed the presence of multiple liver metastases. Because the patient did not respond to octreotide therapy, embolization of the hepatic artery was performed. After this procedure we observed dramatic improvement of the patient's life quality, and rapid disappearance of facial swelling and sleep apnoea symptoms. We conclude that hepatic artery embolization appeared to be an effective method of abolishing obstructive sleep apnoea associated with carcinoid syndrome.

The identification and characterization of mammalian proteins involved in the rejoining of DNA double-strand breaks in vitro

Using a combination of specific assays and biochemical fractionation of mammalian extracts, we have identified multiple activities involved in the rejoining of DNA double-strand breaks. Fractionation of whole cell extracts from calf thymus has identified four biochemically distinct fractions capable of joining double-strand breaks, and an activity Rejoin Enhancement Protein (REP-1), that stimulates this process. We also show that REP-1 directly stimulates a DNA ligase and that this stimulation is associated with the increased turnover of the adenylated intermediate formed by all ATP-dependent DNA ligases. Activity relationships between the rejoining fractions and REP-1 indicates that the joining of double-strand breaks is carried out by protein complexes of which REP-1 is a component. In support of this, the cellular activities identified here that can efficiently rejoin double-strand breaks, do not show detectable adenylation products. Western analysis also shows that several proteins that have been suggested to be involved in the joining of double-strand breaks, such as the Ku heterodimer, are not present in all fractions that contain rejoining activity. These data strongly suggests that many different activities exist that can rejoin double-strand breaks and that this process is not dependent on the presence of proteins such as the end-binding protein Ku.

Prevalence of antibiotic resistance and serotypes in pneumococci in England and Wales: results of observational surveys in 1990 and 1995

OBJECTIVE

To assess the prevalence of antibiotic resistance and serotype distribution among pneumococci in England and Wales in 1990 and 1995.

DESIGN

Observational surveys in March 1990 and March 1995. During two weeks in each survey period all pneumococci isolated in public health laboratories in England and Wales were collected and assessed for sensitivity to antibiotics and the distribution of serogroups or serotypes.

SETTING

The network of public health laboratories throughout England and Wales.

SUBJECTS

1127 individual patient isolates of Streptococcus pneumoniae obtained during the two surveys.

MAIN OUTCOME MEASURES

Sensitivity or resistance to a range of antibiotics; serogroup or serotype.

RESULTS

The prevalence of intermediate or full resistance to penicillin increased from 1.5% in 1990 to 3.9% in 1995 and resistance to erythromycin increased from 2.8% to 8.6%. About 92% of isolates belonged to serogroups or serotypes included in the currently available pneumococcal vaccine.

CONCLUSION

Resistance to penicillin and erythromycin has increased among pneumococci in England and Wales. Continued surveillance to assess further increases in the prevalence of pneumococcal resistance to antibiotics is essential.

Quinolone resistance in Oligella urethralis-associated chronic ambulatory peritoneal dialysis peritonitis

Oligella urethralis is an organism which is normally isolated as a commensal from the genitourinary tract. We describe the first two reported cases of CAPD-associated peritonitis caused by this organism. Both isolates were found to be resistant to ciprofloxacin, while relatively sensitive to a wide range of antimicrobial drugs. These findings indicate that this organism may be an opportunistic pathogen for CAPD patients, and that extensive ciprofloxacin usage provides a selection pressure for emergence of resistance.

Detection of the mec-A gene and phenotypic detection of resistance in Staphylococcus aureus isolates with borderline or low-level methicillinresistance

Eighty-three isolates of Staphylococcus aureus for which MICs of methicillin of 4-16 mg/L had previously been recorded were tested for the presence of the mecA gene with a DNA probe and a PCR assay. There was complete agreement between the results obtained by these methods; 39 isolates were mecA-positive and 44 were mecA-negative. Using the presence of mecA as the defining standard, several phenotypic methods for determining resistance to methicillin were evaluated and a high-inoculum, agar-incorporation breakpoint test was found to offer the best combination of high sensitivity and high specificity. However twenty-seven of the 44 mecA-negative strains were methicillin-resistant according to agar dilution MICs (MIC > 4 mg/L on at least one of the four media used) but none had MICs exceeding 32 mg/L. One of the mecA-positive strains had a methicillin MIC of only 8 mg/L and did not appear to be heteroresistant. The clinical significance of these two groups of 'atypical' isolates may need further investigation. This study highlights the problems of detecting reliably S. aureus with low level methicillin resistance by phenotype methods and the usefulness of direct detection of the mecA gene.

Should ENT out-patients be seen in hospital or General Practitioners' surgeries?

This was a prospective trial involving 1000 consecutive patients attending an ENT out-patient department to assess the degree of investigation and procedures undertaken in routine practice. Results demonstrate that the majority of patients (both new and old) require a procedure which would necessitate either additional staff or equipment if the consultation occurred in a General Practitioner's (GP's) surgery. The results argue against out-patient clinics taking place in a GP's surgery.

Sequential emergence of multi-resistant Klebsiella pneumoniae in Bahrain

During the mid-1980s, nosocomial infections due to aminoglycoside-resistant Klebsiella pneumonia were prevalent in the intensive care unit (ICU) of the Salamanya Medical Centre, Bahrain. In an attempt to control the spread of such organisms, the third-generation cephalosporins were introduced in early 1987. Subsequently there was a marked increase in the incidence of cephalosporin resistance among Klebsiella spp. isolated in the ICU. In 1990, over 60% of Klebsiella isolates were resistant to both cephalosporins and aminoglycosides. Cephalosporin resistance was due to production of extended-spectrum beta-lactamases encoded on the same plasmid as aminoglycoside resistance. The incidence of cephalosporin resistance declined during 1991-1992, which was coincident with severe restrictions on the use of third-generation cephalosporins and the preferential use of ciprofloxacin and imipenem for nosocomial klebsiella infections. Sequential overuse of aminoglycosides and cephalosporins for nosocomial klebsiella infection may select for organisms resistant to both classes of antibiotics.

Current perspectives on glycopeptide resistance

In the last 5 years, clinical isolates of gram-positive bacteria with intrinsic or acquired resistance to glycopeptide antibiotics have been encountered increasingly. In many of these isolates, resistance arises from an alteration of the antibiotic target site, with the terminal D-alanyl-D-alanine moiety of peptidoglycan precursors being replaced by groups that do not bind glycopeptides. Although the criteria for defining resistance have been revised frequently, the reliable detection of low-level glycopeptide resistance remains problematic and is influenced by the method chosen. Glycopeptide-resistant enterococci have emerged as a particular problem in hospitals, where in addition to sporadic cases, clusters of infections with evidence of interpatient spread have occurred. Studies using molecular typing methods have implicated colonization of patients, staff carriage, and environmental contamination in the dissemination of these bacteria. Choice of antimicrobial therapy for infections caused by glycopeptide-resistant bacteria may be complicated by resistance to other antibiotics. Severe therapeutic difficulties are being encountered among patients infected with enterococci, with some infections being untreatable with currently available antibiotics.

Urinary isolates of apramycin-resistant Escherichia coli and Klebsiella pneumoniae from Dublin

Twenty-two gentamicin-resistant urinary isolates of Escherichia coli and five gentamicin-resistant urinary isolates of Klebsiella pneumoniae from a Dublin hospital were examined for resistance to the veterinary aminoglycoside antibiotic apramycin. Five isolates of E. coli and one isolate of K. pneumoniae were found to be resistant. The apramycin-resistant isolates, which were also resistant to the veterinary anthelmintic agent hygromycin B, hybridized with a DNA probe for the gene encoding the enzyme 3-N-aminoglycoside acetyltransferase type IV (AAC(3)IV). Resistance to apramycin and hygromycin B was co-transferable in four of the five isolates of E. coli and the isolate of K. pneumoniae. In one isolate of E. coli apramycin resistance was not transferable. On the basis of their restriction enzyme digestion profiles and the antimicrobial resistance traits encoded, the transferable plasmids encoding resistance to apramycin and hygromycin B comprised three distinct types. Genetic linkage between the gene encoding AAC(3)IV and genes encoding resistance to ampicillin and either tetracycline or trimethoprim, means that the relatively widespread use of these antimicrobial agents provides a selective pressure for the persistence of resistance to apramycin and gentamicin even in the absence of bacterial exposure to aminoglycosides.

Theory M: A restructuring process

Through the Nursing Incentive Reimbursement Award (NIRA) Program initiated by the New Jersey Department of Health, a medical center tested, over a two-year time frame, the impact of a staff-developed "Theory M" nursing model. Three nursing units served as control groups and one as the experimental group that incorporated the following features: restructuring of a nursing unit through the redefinition of roles; modifying nurse staffing patterns to change existing ratio of RNs to NAs; incorporating matrix management principles; developing, implementing and evaluating training and educational programs; and renovating a nursing unit.

Symptomatic Rathke's cleft cyst with hypophysitis

We report a case of symptomatic Rathke's cleft cyst (RCC) with associated chronic hypophysitis. Symptomatic RCCs are rare and an associated inflammatory reaction is even rarer. The clinical and pathological findings are discussed in the light of previous published reports, together with the problems involved in making a preoperative diagnosis in such cases.

Haemophilus aphrophilus discitis and vertebral osteomyelitis

An unusual case of discitis and vertebral osteomyelitis due to Haemophilus aphrophilus is described. Infections due to this organism have usually responded to treatment with beta-lactam antibiotics. However, our isolate was resistant to third-generation cephalosporins which has not been reported previously in the world literature. The patient made a good clinical response to ciprofloxacin treatment.

The pathogenicity of enterococci

In order to produce infection, enterococci must be able to colonize host tissues, resist the host's non-specific and immune defence mechanisms and produce pathological changes. With regard to colonization of host tissues, adherence assays have shown that enterococci can attach to intestinal and urinary tract epithelial cells and heart cells by means of adhesins expressed on the bacterial surface. The expression of these adhesins by enterococci has further been shown to be affected by bacterial growth conditions. In addition, the adherence of Enterococcus faecalis to renal tubular cells in vitro is enhanced if the organisms produce aggregation substance, a proteinaceous surface material that aggregates donor and recipient bacteria to facilitate plasmid transfer. Bacterial growth conditions also affect the interaction of enterococci with polymorphonuclear leucocytes (PMNLs), with serum-grown organisms showing less association with PMNLs than organisms grown in broth. Efficient killing of enterococci by PMNLs in vitro requires the presence of serum complement proteins and is enhanced by anti-enterococcal antibodies. Enterococci produce a number of factors that may be associated with pathological changes in the host. Both sex pheromones and plasmid-encoded pheromone inhibitors produced by E. faecalis are chemotactic for PMNLs in vitro, and may mediate, at least in part, the inflammatory response often associated with enterococcal infection. E. faecalis may also produce a plasmid-encoded haemolysin, which is associated with increased severity of infection. In addition, enterococci are capable of inducing platelet aggregation and tissue factor-dependent fibrin production, which may be relevant to the pathogenesis of enterococcal endocarditis.(ABSTRACT TRUNCATED AT 250 WORDS)

Speech restoration following total laryngo-pharyngectomy with free jejunal repair

Nine patients who have undergone total laryngo-pharyngectomy with free jejunal reconstruction between 1984 and 1993, have had Blom-Singer valves inserted. All patients had little or no voice prior to valve insertion, compared with a good but gravelly voice after valve insertion. Tracheo-oesophageal puncture and valve insertion provides a safe and reliable means of restoring voice after laryngo-pharyngectomy with free jejunal repair.

Vertebro-carotid anastomosis as a cause of uncontrollable epistaxis

Uncontrolled epistaxis may require a long hospital stay, multiple blood transfusions and multiple arterial ligations. This case report highlights vertebro-carotid anastomosis as a rare cause of uncontrolled epistaxis. The importance of angiography in the identification of rare arterial anastomoses is stressed.

Gentamicin resistance in clinical isolates of Escherichia coli encoded by genes of veterinary origin

Seven (27%) of 26 gentamicin-resistant human clinical isolates of Escherichia coli were resistant to the veterinary aminoglycoside antibiotic apramycin. A gentamicin-resistant Klebsiella pneumoniae isolate from a patient infected with gentamicin/apramycin-resistant E. coli was also resistant to apramycin. DNA hybridisation studies showed that all gentamicin/apramycin-resistant isolates contained a gene encoding the enzyme 3-N-aminoglycoside acetyltransferase type IV (AAC[3]IV) that mediates resistance to gentamicin and apramycin in bacteria isolated from animals. Seven of the eight gentamicin/apramycin-resistant isolates were also resistant to the veterinary antihelminthic agent hygromycin B, a phenomenon observed previously in gentamicin/apramycin-resistant Enterobacteriaceae isolated from animals. Resistance to gentamicin/apramycin and hygromycin B was co-transferable in six of the isolates. Restriction enzyme analysis of plasmids in apramycin-resistant transconjugants derived from E. coli and K. pneumoniae isolates from the same patient were virtually identical, suggesting that inter-generic transfer of plasmids encoding apramycin resistance had occurred in vivo. These findings support the view that resistance to gentamicin and apramycin in clinical isolates of E. coli results from the spread of resistant organisms from animals to man, with subsequent inter-strain or inter-species spread, or both, of resistance genes on transferable plasmids.

Genetics of oxacillin resistance in clinical isolates of Streptococcus pneumoniae that are oxacillin resistant and penicillin susceptible

It has recently been reported that penicillin-sensitive pneumococci may exhibit reduced susceptibility to oxacillin, resulting in their misclassification as being penicillin resistant by oxacillin disk testing. Intermediate oxacillin resistance (MIC, 1.0 microgram/ml) in three of these apparently unrelated penicillin-susceptible clinical isolates of Streptococcus pneumoniae isolated in the United Kingdom and in four Spanish isolates was shown to be solely due to the acquisition of a gene encoding an altered penicillin-binding protein (PBP), PBP2X. PBP2X genes cloned from typical penicillin-resistant isolates of S. pneumoniae that possessed high-level oxacillin resistance were shown to be able to transform susceptible isolates of S. pneumoniae to intermediate oxacillin resistance. In all instances, the intermediately oxacillin-resistant PBP2X transformants retained susceptibility to penicillin (MIC, 0.06 microgram/ml). Under appropriate selective pressure, the acquisition of a low-affinity PBP2X by penicillin-susceptible pneumococci could result in an increasing number of false positives for penicillin resistance among isolates of S. pneumoniae screened with oxacillin. Additionally, these intermediately oxacillin-resistant isolates showed reduced susceptibility to cefotaxime, an agent likely to be prescribed in place of penicillin for the treatment of serious infections due to these apparently penicillin-resistant organisms.

SPROUT: recent developments in the de novo design of molecules

SPROUT is a computer program for constrained structure generation. It is designed to generate molecules for a range of applications in molecular recognition. The program uses a number of approximations that enable a wide variety of diverse structures to be generated. Practical use of the program is demonstrated in two examples. The first demonstrates the ability of the program to generate candidate inhibitors for a receptor site of known 3D structure, specifically the GDP binding site of p21. In the second example, structures are generated to fit a pharmacophore hypothesis that models morphine agonists.

Nosocomial spread of Staphylococcus aureus showing intermediate resistance to methicillin

A nosocomial outbreak of infection and colonization involving six patients and caused by a strain of Staphylococcus aureus showing intermediate resistance to methicillin (MIC = 4-8 mg l-1) is described. The outbreak was associated with skin-carriage of the epidemic strain by a nurse suffering from severe eczema. The reduced susceptibility of the outbreak strain to methicillin was associated with beta-lactamase production. Elimination or inhibition of beta-lactamase activity produced a two-fold decrease in methicillin MIC. There was no evidence for the presence of either penicillin-binding protein 2a or the corresponding mec gene, which mediate resistance in fully methicillin-resistant strains.

Microbial colonization of Blom-Singer prostheses in postlaryngectomy patients

The microbial colonization of 44 Blom-Singer valves obtained from 16 patients over an 11-month period was investigated both by standard microbial culture methods and scanning electron microscopy (SEM). The valves were all removed from the patients after failure to function correctly. The microbiology cultures revealed that Candida species and Staphylococcus aureus were present either individually or in combination on 43 valves. SEM showed yeast hyphae attached to and penetrating the surfaces of the 5 valves examined. Colonies of staphylococci were also seen on 2 of these 5 valves. Unlike similar investigations on other voice prostheses, S aureus colonization was associated with Candida colonization and valve failure.

In-vitro characteristics of glycopeptide resistant strains of Staphylococcus epidermidis isolated from patients on CAPD

The low-level resistance of three clinical isolates of Staphylococcus epidermidis to glycopeptide antibiotics was found to be constitutive, not inducible, and was not increased by passage in the presence of either vancomycin or teicoplanin. There was no loss of resistance on repeated passage in antibiotic-free broth. In contrast, the susceptibility to these antibiotics declined for S. epidermidis NCTC 6513 that been sequentially passaged in either vancomycin or teicoplanin whereas the variants reverted to being susceptible on further passage in antibiotic-free broth. Antibiotic activity was almost completely abolished when cultures of the resistant S. epidermidis strains were exposed overnight to sub-MIC concentrations. No evidence of drug-modifying activity was obtained. Experiments of antibiotic-binding activity indicated that the resistant strains exhibited an increased ability to sequester antibiotics which was particularly rapid in stationary phase cultures when most of the antibiotic activity disappeared from the growth medium within 30 min of exposure to the drugs. Teicoplanin was sequestered more efficiently than vancomycin and some loss of activity was also observed when stationary phase cultures of S. epidermidis NCTC 6513 were exposed to glycopeptides. These results suggest that glycopeptide-resistant isolates of S. epidermidis are able to bind large amounts of these antibiotics, possibly at sites unassociated with the D-alanyl-D-alanine target, and that teicoplanin is bound more avidly than vancomycin.

The emergence of vancomycin resistance in renal dialysis

Intraperitoneal vancomycin is used in the treatment of peritonitis in patients undergoing continuous ambulatory peritoneal dialysis (CAPD). We describe the emergence of low-level glycopeptide-resistance in five Gram-positive species over a one-year period. Isolation of these organisms was associated with vancomycin treatment failure in four patients who had had numerous episodes of peritonitis. Clinicians and microbiologists should be aware that repeated administration of glycopeptides to such patients might lead to the emergence of organisms resistant to these antibiotics.

Prevalence of the type I and type II DHFR genes in trimethoprim-resistant urinary isolates of Escherichia coli from Greece

Trimethoprim resistance in 64 Escherichia coli urinary isolates from five hospitals in Greece was studied. Of the 40 isolates exhibiting transferable high-level resistance (MIC > 1024 mg/L), 21 hybridized with a specific probe for dihydrofolate reductase (DHFR) I, 13 with a probe for DHFR II, and one with a probe for DHFR V. Eleven isolates hybridized with a probe for transposon Tn7. Among the 17 isolates with non-transferable high-level resistance, seven hybridized with the probe for DHFR I, three with the probe for DHFR II, and eight were Tn7-positive. None of the seven isolates with low-level resistance (MIC 4-1024 mg/L) reacted with the probes used. Of the 28 isolates positive for DHFR I, 12 (43%) failed to hybridize with the Tn7 probe. Conversely, three isolates hybridized with the Tn7 probe, but not with the probe for DHFR I. Colony hybridization experiments showed that all but three transconjugants reacted similarly to their respective parent strains. The plasmids coding for trimethoprim-resistant DHFRs were found to differ on the basis of restriction enzyme analysis. These findings suggest that trimethoprim resistance among E. coli urinary isolates in Greece is mediated predominantly by heterogeneous transferable plasmids encoding either DHFR I or DHFR II. The dissociation between DHFR I and Tn7, together with the high incidence of trimethoprim-resistant isolates which did not hybridize with the probes for the common DHFR I or II types, indicates the continued evolution of trimethoprim resistance determinants.