Are routine sensitivity test data suitable for the surveillance of resistance? Resistance rates amongst Escherichia coli from blood and CSF from 1991-1997, as assessed by routine and centralized testing

Surveillance of antibiotic resistance can be undertaken by compilation of routine data or by central testing of isolates. Routine results can be obtained cheaply and in sufficient quantities for correlation with population and prescribing denominators but there is concern about their quality. As one of a series of ongoing studies to assess this quality, we compared the proportions of resistance amongst Escherichia coli from patients with bacteraemia or meningitis between 1991 and 1997 (i) as recorded in routine data reported to the PHLS and (ii) as found in tests performed at the PHLS Laboratory of Enteric Pathogens (LEP). These two data sets both showed an overall upward trend in the proportion of isolates resistant to ampicillin, trimethoprim, gentamicin and ciprofloxacin. The average annual percentage increase in resistance was estimated in separate logistic regression models, and 95% confidence intervals (CI) were determined. The annual percentage increases in the proportions of isolates reported resistant were similar in the two data sets for trimethoprim, gentamicin and ciprofloxacin but differed for ampicillin. The upward trends were statistically significant except for gentamicin resistance in the LEP data set, where the 95% CI straddled zero. The proportions of resistant isolates for each antibiotic in the two data sets each year were in poorer agreement than the trends; however, the 95% CI of the difference of proportions resistant between the routine and LEP data sets straddled zero in 4 or 5 of the 7 years studied. Some discrepancies might be explained by geographical bias in the sampling or by differences in definitions of resistance. Thus (i) the proportion of resistant isolates tested at LEP almost always fell within the ranges bounded by the highest and lowest proportions for individual Regional Health Authorities, as recorded in the routine data, and (ii) the fact that LEP consistently recorded less gentamicin resistance but more ciprofloxacin resistance than the routine could be explained by breakpoint differences. We conclude that routine susceptibility data for ampicillin, ciprofloxacin, gentamicin and trimethoprim appear sound for E. coli and might be suitable for correlation with other data, e.g. for prescribing.

Activity of linezolid against multi-resistant gram-positive bacteria from diverse hospitals in the United Kingdom

The in vitro activity of linezolid, an oxazolidinone, was assessed against 374 gram-positive cocci, with an emphasis on testing multi-resistant, epidemiologically unrelated isolates. MICs of linezolid for staphylococci, pneumococci and streptococci had a narrow range, from 0.5 to 2 mg/L, whereas MICs for enterococci were uniformly 4 mg/L. For all the species tested, the MICs of linezolid were unrelated to those of other antimicrobials. Linezolid appears to be a potentially useful drug for infections caused by gram-positive cocci.

Bacteraemia and antibiotic resistance of its pathogens reported in England and Wales between 1990 and 1998: trend analysis

OBJECTIVES

Determination of causes, trends, and antibiotic resistance in reports of bacterial pathogens isolated from blood in England and Wales from 1990 to 1998.

DESIGN

Description of bacterial isolates from blood, judged to be clinically significant by microbiology staff, reported to the Communicable Disease Surveillance Centre.

SETTING

Microbiology laboratories in England and Wales.

SUBJECTS

Patients yielding clinically significant isolates from blood.

MAIN OUTCOME MEASURES

Frequency and Poisson regression analyses for trend of reported causes of bacteraemia and proportions of antibiotic resistant isolates.

RESULTS

There was an upward trend in total numbers of reports of bacteraemia. The five most cited organisms accounted for over 60% of reports each year. There was a substantial increase in the proportion of reports of Staphylococcus aureus resistant to methicillin, Streptococcus pneumoniae resistance to penicillin and erythromycin, and Enterococcus faecalis and Enterococcus faecium resistance to vancomycin. No increase was seen in resistance of Escherichia coli to gentamicin.

CONCLUSIONS

Reports from laboratories provide valuable information on trends and antibiotic resistance in bacteraemia and show a worrying increase in resistance to important antibiotics.

Outcome of surgery for acromegaly--the experience of a dedicated pituitary surgeon

Previous large series of outcome following pituitary surgery for acromegaly, including our own, have demonstrated poor results, with cure, defined as GH <5 mU/l, achieved in only 33-42% of patients. In our previous series, surgery was performed by one of eight different surgeons. Largely based on the disappointing results of this previous audit of outcome, our practice since 1990 has been, whenever possible, to refer all patients with acromegaly to a dedicated pituitary surgeon (APJ). The objective of the current study was to re-analyse the outcome of surgical treatment for acromegaly since instituting this change. Tumour size and extension was determined on CT/MRI scanning. Biochemical cure was defined as a basal GH <5 mU/l or a nadir GH of <2 mU/l across an OGTT following initial pituitary surgery. Surgery was performed on 66 patients and 42 (64%) were cured, compared with 26/78 (33%) in our previous study (p<0.0005, chi (2) test). The cure rate for microadenomas (n=22) was 86%, and for macroadenomas 52%, compared with 54% (p<0.05, chi (2) test) and 30% (p<0.05, chi (2) test) respectively, in our previous study. We conclude that surgical outcome for acromegaly is enhanced if patients are operated on by a single experienced surgeon.

Relationship between mutations in parC and gyrA of clinical isolates of Streptococcus pneumoniae and resistance to ciprofloxacin and grepafloxacin

The mechanisms of resistance to ciprofloxacin and grepafloxacin were studied in 54 clinical isolates of Streptococcus pneumoniae. Restriction fragment length polymorphism analysis following HinfI digestion was used with DNA sequencing to identify mutations in the quinolone resistance-determining regions (QRDRs) of the parC and gyrA genes. Ciprofloxacin MICs up to 16 mg/L were not associated with mutations to these genes in approximately half of the isolates. In other isolates, moderate levels of ciprofloxacin resistance (MIC 8-16mg/L) were associated with an alteration of ParC, most commonly entailing replacement of serine-79 by phenylalanine. High-level ciprofloxacin resistance (MIC 32-128 mg/L) entailed the additional mutation of GyrA with substitution of serine-83 by phenylalanine. Grepafloxacin MICs >4 mg/L were associated with this GyrA mutation alone; no relationship was detected between grepafloxacin MICs and mutation of the QRDR of parC.

Admission rates, early readmission rates and patient acceptability of 142 cases of day case septoplasty

Day case surgery should be confined to those procedures where less than 3% of patients require admission. The aim of this study was to establish the admission rates, early readmission rates and patient acceptability of 142 consecutive cases of day case septoplasty. Data acquisition was by retrospective postal questionnaire. One hundred and fifty-three patients were studied and data was acquired on 142. Ninety per cent (128/142) of patients had operations on afternoon lists. Admissions were 7/142 (5%), the early readmission rate (within 24 h) was 0% and 25/142 (17%) of patients felt they would rather have stayed in hospital for the first night after surgery. The conclusion of this work is that day case septoplasty is an acceptable practice in appropriately selected patients who are operated upon in the morning and when the technique described here is applied. An acceptably small proportion of planned day cases may require admission.

Gonococcal infection of human fallopian tube mucosa in organ culture: relationship of mucosal tissue TNF-alpha concentration to sloughing of ciliated cells

BACKGROUND AND OBJECTIVES

An experimental model consisting of gonococcal infection of human fallopian tube mucosa in organ culture has proven useful in studying the molecular pathogenesis of acute gonococcal salpingitis and postsalpingitis sequelae. Gonococcal infection of human fallopian tube mucosa in organ culture results in the sloughing of ciliated epithelial cells from the mucosa. This damage to the mucosa can be quantified on fallopian tube pieces by an assay of the percent of the periphery that has ciliary activity (PPCA) remaining at specific time points after infection. Although assay of the PPCA has been quite valuable, it is labor-intensive, somewhat subjective, and requires that the observers have training and experience. A more practical assay for genital mucosal damage is desirable for further investigations that employ the fallopian tube experimental model. Gonococcal infection of fallopian tube mucosa in organ culture also results in the production of easily quantified tumor necrosis factor-alpha (TNF-alpha) by the mucosa. Furthermore, treatment of the organ cultures with recombinant human TNF-alpha (rHuTNFalpha) alone also causes sloughing of ciliated cells from the mucosa. These findings strongly suggest that TNF-alpha is a mediator of the mucosal damage that attends gonococcal infection.

GOALS OF THE STUDY

To determine: (1) whether the PPCA values and the TNF-alpha concentrations in fallopian tube mucosal tissues correlate closely enough to allow prediction of the PPCA from a measurement of the mucosal tissue TNF-alpha concentration; and (2) whether the correlation of the TNF-alpha mucosal tissue concentration with the sloughing of ciliated cells (measured by the PPCA) supports the hypothesis that induction of TNF-alpha by gonococcal infection, with resultant sloughing of ciliated cells, is likely to be a major pathogenic mechanism of gonococcal salpingitis and might mediate postsalpingitis infertility and ectopic pregnancy.

STUDY DESIGN

A metaanalysis was performed on studies from three research groups (two laboratories in the United States and one in the United Kingdom, using identical techniques for quantifying the PPCA, TNF-alpha, or both.

RESULTS

There was a close and statistically significant correlation between the TNF-alpha mucosal tissue concentration and the proportion of ciliated cells lost from the mucosa as measured by the PPCA (r = 0.95, p < 0.001). Therefore, as the mucosal tissue concentration of endogenous TNF-alpha increased, the loss of ciliated cells from the epithelium increased proportionately.

CONCLUSIONS

During gonococcal infection of human fallopian tube mucosa in organ culture, the mucosal tissue concentration of TNF-alpha can be used to predict the PPCA, and therefore, the extent of mucosal damage. This finding should facilitate studies of the molecular pathogenesis of infectious diseases involving human genital mucosa. Further, the close correlation of mucosal TNF-alpha concentration with genital mucosal damage, evaluated by the PPCA, supports the hypothesis that induction of the proinflammatory cytokine, TNF-alpha, by gonococcal infection, with resultant inflammation and sloughing of ciliated cells, is an important pathogenic mechanism of gonococcal salpingitis and may mediate postsalpingitis infertility and ectopic pregnancy as well.

Long-term morbidity from Pope Ear Wicks

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In-vitro activity of sanfetrinem against isolates of Streptococcus pneumoniae and Staphylococcus aureus

The activity of sanfetrinem (previously GV104326), was assessed against 168 isolates of Streptococcus pneumoniae and 90 isolates of Staphylococcus aureus. These isolates included a range of serotypes or phage types, and varied in their susceptibility to other antibiotics. Sanfetrinem exhibited good anti-pneumococcal activity, with MIC90s of < or = 0.007 mg/L and 0.5 mg/L for penicillin-susceptible and penicillin-resistant isolates, respectively. Sanfetrinem was also active against methicillin-susceptible staphylococci (MIC90 = 0.06 mg/L). However, the MICs of sanfetrinem for isolates with methicillin MICs of 8-16 mg/L and > or = 32 mg/L were 0.25-1 mg/L and 8->32 mg/L, respectively.

Evaluation of disc diffusion and Etest for determining the susceptibility of Staphylococcus aureus to mupirocin

The susceptibilities to mupirocin of 102 selected clinical isolates of Staphylococcus aureus and of control strain S. aureus NCTC 6571 were determined by disc diffusion (using discs containing 5, 15, 25, 30, 50 and 200 microg of mupirocin) and Etest and the results were compared with MICs determined using an agar incorporation method. On the basis of agar incorporation MICs, 42 isolates were sensitive to mupirocin (MIC < or = 4 mg/L), 39 showed low-level resistance (MICs = 8-128 mg/L) and 22 were highly resistant (MICs > or = 256 mg/L) and contained the mupA resistance gene. Using Stokes' criteria, none of the discs used gave major errors (sensitive isolates classified as highly resistant) or very major errors (highly resistant isolates classified as sensitive) in assigning a category of susceptibility, but minor errors (a difference of one category) were noted with all strengths. The best correlation with agar incorporation MIC was obtained with 25 microg mupirocin discs, which classified correctly 98 (95%) isolates, while worse correlations were noted with 5 microg and 200 microg discs which are the only types currently available commercially, for which there were 47 and 30 minor errors, respectively. The MICs found by Etest were the same as, or lower than, those determined by agar incorporation. Etests classified correctly all 42 mupirocin-sensitive isolates, 19 (49%) low-level resistant isolates and 16 (73%) highly resistant isolates. Two isolates that contained the mupA gene and showed agar incorporation MICs of 256 mg/L and 512 mg/L were not classified as highly resistant by any of the diffusion methods used. Agar incorporation MIC determination, possibly supported by detection of the mupA gene, offers the most effective means of identifying high-level mupirocin resistance in S. aureus, although the Etest also proved to be reproducible. However, we conclude that 25 microg discs warrant further evaluation for possible use in clinical laboratories, as they appear to be more reliable than the discs currently available.

Antibiotic resistance among clinically important gram-positive bacteria in the UK

The resistance of bacteria to antibiotics, particularly those used for first-line therapy, is an increasing cause for concern. In the UK, the prevalence of resistance to methicillin and mupirocin in Staphylococcus aureus, and to penicillin and macrolides in Streptococcus pneumoniae, appear to be increasing. There has also been an increase in the number of hospitals where glycopeptide-resistant enterococci are known to have been isolated. The increases in methicillin-resistant S. aureus and glycopeptide-resistant enterococci are due, in part, to the inter-hospital spread of epidemic strains. Although new quinolones and streptogramins with activity against Gram-positive bacteria (including strains resistant to currently available agents) are under development, there is no reason to believe that resistance to these agents will not emerge. The control of resistance in Gram-positive bacteria will require a multi-faceted approach, including continued and improved surveillance, a reduction in the unnecessary use of antibiotics, and the application of other strategies such as vaccination.

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.