Prevalence of legionella waterline contamination and Legionella pneumophila antibodies in general dental practitioners in London and rural Northern Ireland.

OBJECTIVES: To determine the prevalence of legionellae in dental unit waterlines (DUWL) in general dental practices in London and rural Northern Ireland and whether the organism occurs at a high enough frequency and magnitude in DUWL to represent a threat to dentists' health. MATERIALS AND METHOD: Two hundred and sixty six (166 London, 100 Northern Ireland) randomly selected dental surgeries were recruited. Standardised 250 ml water samples were taken from the DUWL and 1 litre samples from the surgery cold water tap to measure the prevalence of legionellae. The dentists provided a blood sample for legionella serology. RESULTS: The prevalence of legionellae was very low (0.37%). Legionellae were not isolated from DUWL or surgery basin taps in Northern Ireland. Legionella spp were isolated from the DUWL and surgery basin of one practice in London and from the cold water supply of a further three practices. The prevalence of Legionella pneumophila antibodies was less than that seen in a comparable group of London blood donors. CONCLUSION: The risk to dentists' health from potential exposure to legionellae in this cohort of dentists was very low and this was confirmed by the very low seroprevalence and antibody titres to legionella detected in the dentists.

Timing and aetiology of bacterial infections in a liver intensive care unit.

We undertook a prospective study of 887 consecutive adult patients admitted over an 11 year period to a liver intensive care unit. One or more bacterial infections occurred in 335 (37.8%) patients. Gram-positive cocci predominated. In relation to the date of admission these infections occurred in a statistically significant sequence. Streptococci infections were earliest (median time to infection two days), followed by Staphylococcus aureus (three days), coagulase-negative staphylococci (six days) and enterococci (eight days). Escherichia coli infections occurred earlier than those due to klebsiella-enterobacter (two vs seven days; P = 0.0001) and, overall, Enterobacteriaceae earlier than non-fermentative Gram-negatives (four vs. eight days; P = 0.0081). This study contributes to the management of high-dependency patients by confirming statistically the timing and sequence of infecting bacteria in patients with acute liver failure.

Distribution of endo-beta-N-acetylglucosaminidase amongst enterococci.

Enterococci are becoming increasingly important nosocomial pathogens, a fact mainly attributed to their antimicrobial resistance profiles. However, the enzymic activities required for these organisms to proliferate in vivo have received little attention. Enterococcus faecalis has been shown previously to produce an endo-beta-N-acetylglucosaminidase activity which cleaves high mannose-type glycans in glycoproteins between the N-acetylglucosamine residues of the pentasaccharide core. This study investigated the distribution of this endoglycosidase activity amongst the other enterococcal species. Ribonuclease B, a high mannose-type glycoprotein, was used as a substrate and endoglycosidase activity was demonstrated by a combination of matrix-assisted laser desorption ionisation time-of-flight mass spectrometry and high pH anion-exchange chromatography. Endo-beta-N-acetylglucosaminidase activity was present in 10 of the 18 enterococcal species isolated from both human and animal sources, including all E. faecalis strains. The most notable exception was the lack of this activity in all E. faecium isolates tested. All enterococcal species possessing endoglycosidase activity utilised the liberated glycans to support bacterial growth.

Mannosidase production by viridans group streptococci.

The production of mannosidase activity by all currently recognized species of human viridans group streptococci was determined using an assay in which bacterial growth was dependent on the degradation of the high-mannose-type glycans of RNase B and subsequent utilization of released mannose. RNase B is an excellent substrate for the demonstration of mannosidase activity since it is a glycoprotein with a single glycosylation site which is occupied by high-mannose-type glycoforms containing five to nine mannose residues. Mannosidase activity was produced only by some members of the mitis group (Streptococcus mitis, Streptococcus oralis, Streptococcus gordonii, Streptococcus cristatus, Streptococcus infantis, Streptococcus parasanguinis, and Streptococcus pneumoniae) and Streptococcus intermedius of the anginosus group. None of the other species within the salivarius and mutans groups or Streptococcus peroris and Streptococcus sanguinis produced mannosidase activity. Using matrix-assisted laser desorption ionization time-of-flight mass spectrometry, it was demonstrated that the Man(5) glycan alone was degraded while Man(6) to Man(9), which contain terminal alpha(1-->2) mannose residues in addition to the alpha(1-->3), alpha(1-->6), and beta(1-->4) residues present in Man(5), remained intact. Investigations on mannosidase production using synthetic (4-methylumbelliferone- or p-nitrophenol-linked) alpha- or beta-mannosides as substrates indicated that there was no correlation between degradation of these substrates and degradation of the Man(5) glycan of RNase B. No species degraded these alpha-linked mannosides, while degradation of the beta-linked synthetic substrates was restricted to strains within the Streptococcus anginosus, S. gordonii, and S. intermedius species. The data generated using a native glycoprotein as the substrate demonstrate that mannosidase production within the viridans group streptococci is more widely distributed than had previously been considered.

Intra- and inter-generic plasmid-mediated spread of cephalosporin and aminoglycoside resistance amongst Klebsiella aerogenes K41 and other enterobacteria.

Klebsiella aerogenes K41, resistant to third generation cephalosporins and aminoglycosides, was isolated from clinical samples of 153 in-patients. Blood cultures accounted for 24 (15.7%) of isolates. The MIC(90) of ceftazidime for the isolates of 84 patients was >512 mg/l and was reduced to 2.0 by 4 mg/l of clavulanic acid, but only to 64 by 4 mg/l of sulbactam. Isolates of K. aerogenes K41 produced extended-spectrum beta-lactamase (ESBL) SHV-5 and TEM-1, identified by isoelectric focusing. Plasmid profiles showed that co-dissemination of cephalosporin and aminoglycoside resistance, plus ESBL production, coincided with the acquisition of a 116-kb plasmid. This plasmid was transferable in vitro from K. aerogenes K41 to other serotypes and genera of the Enterobacteriaceae.

Glycopeptide-resistant Enterococcus faecium infections in paediatric liver transplant recipients: safety and clinical efficacy of quinupristin/dalfopristin.

We describe our experience of quinupristin/dalfopristin for glycopeptide-resistant Enterococcus faecium (GREF) infections in 19 paediatric liver transplant recipients. The median patient age was 2 years and all were receiving immunosuppressive regimens. Quinupristin/dalfopristin was well tolerated and complete resolution of infection was seen in 74% of patients. Side-effects included reversible elevation of serum alkaline phosphatase, skin rash, itching, diarrhoea and vomiting, but therapy was not withdrawn from any patient. Quinupristin/dalfopristin appears safe and efficacious in critically ill immunocompromised children with renal or hepatic impairment.

The systemic inflammatory response syndrome in acute liver failure.

The systemic inflammatory response syndrome (SIRS) in acute liver failure (ALF), in which infection is common, has not been studied. In this study, SIRS components were recorded on admission and during episodes of infection, in 887 ALF patients admitted to a single center during an 11-year period. Overall, 504 (56.8%) patients manifested a SIRS during their illness, with a maximum of 1, 2, and 3 concurrent SIRS components in 166, 238, and 100 patients, respectively. In 353 (39.8%) patients who did not become infected, a SIRS on admission was associated with a more critical illness, subsequent worsening of encephalopathy, and death. Infected patients more often developed a SIRS and one of greater magnitude. The magnitude of the SIRS in 273 patients with bacterial infection correlated with mortality, being 16.7%, 28.4%, 41.2%, and 64.7% in patients with 0, 1, 2, and 3 maximum concurrent SIRS components, respectively. Similar correlations with mortality were seen for SIRS associated with fungal infection, bacteremia, and bacterial chest infection. Fifty-nine percent of patients with severe sepsis died, as did 98% of those with septic shock. A significant association was found between progressive encephalopathy and infection. Infected patients with progressive encephalopathy manifested more SIRS components than other infected patients. For patients with a SIRS, the proportions of infected and noninfected patients manifesting worsening encephalopathy were similar. In ALF, the SIRS, whether or not precipitated by infection, appears to be implicated in the progression of encephalopathy, reducing the chances of transplantation and conferring a poorer prognosis.

Infection control training: evaluation of a computer-assisted learning package.

An evaluation of the training module of an interactive infection control computer-assisted learning (CAL) software program was carried out with ward-based nurses, third-year medical students and infection control personnel. All nursing staff, 87% of the medical students and all infection control staff found the programme easy and enjoyable to use. The module was accessed 3101 times on the hospital network in 18 months with usage settling to between 100-150 times per month. There was a higher level of use by night-duty and weekend staff. Medical students gained as much infection control knowledge from using the CAL package (increase in correct responses from 63.5% to 83.4%;P<0.0001) as they did from a formal lecture (increase in correct responses from 62.1% to 79.5%;P<0.0001). We conclude the training module which is accessible on the hospital wards and across the academic network, is a convenient and effective way for staff and students to gain a basic understanding in evidence-based infection control practices, at locations and times suitable for them.

Mechanisms of resistance to quinupristin-dalfopristin among isolates of Enterococcus faecium from animals, raw meat, and hospital patients in Western Europe.

Twenty-eight quinupristin-dalfopristin-resistant isolates of Enterococcus faecium from hospital patients and nonhuman sources in European countries were studied. High-level resistance (MICs, >/=32 microg/ml) was associated with the presence of vat(E) (satG) (14 isolates ¿50%) or vat(D) (satA) (6 isolates ¿21%). These genes were not detected in eight (29%) isolates with lower levels of quinupristin-dalfopristin resistance (MICs, 4 to 16 microg/ml). This suggests the presence of further mechanisms of resistance to quinupristin-dalfopristin in E. faecium.

Production of an endo-beta-N-acetylglucosaminidase activity mediates growth of Enterococcus faecalis on a high-mannose-type glycoprotein.

Enterococcus faecalis is associated with a high proportion of nosocomial infections; however, little is known of the ability of this organism to proliferate in vivo. The ability of RNase B, a model glycoprotein with a single N-glycosylation site occupied by a family of high-mannose-type glycans (Man(5)- to Man(9)-GlcNAc(2)), to support growth of E. faecalis was investigated. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of RNase B demonstrated a reduction in the molecular mass of this glycoprotein during bacterial growth. Further analysis by matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry revealed that this mass shift was due to the degradation of all high-mannose-type glycoforms to a single N-linked N-acetylglucosamine residue. High-pH anion-exchange chromatography analysis during exponential growth demonstrated the presence of RNase B-derived glycans in the culture supernatant, indicating the presence of an endoglycosidase activity. The free glycans were eluted with the same retention times as those generated by the action of Streptomyces plicatus endo-beta-N-acetylglucosaminidase H on RNase B. The cleavage specificity was confirmed by MALDI-TOF analysis of the free glycans, which showed glycan species containing only one N-acetylglucosamine residue. No free glycans were detectable after 5 h of bacterial growth, and we have subsequently demonstrated the presence of mannosidase activity in E. faecalis, which releases free mannose from RNase B-derived glycans. We propose that this deglycosylation of glycoproteins containing high-mannose-type glycans and the subsequent degradation of the released glycans by E. faecalis may play a role in the survival and persistence of this nosocomial pathogen in vivo.

Identification and antibiotic susceptibility of Nocardia farcinica and N. nova in the UK.

Nocardia asteroides has long been recognised as a heterogeneous group of organisms. The description and identification of two new subgroups, N. farcinica and N. nova, in other countries encouraged us to re-examine a collection of N. asteroides isolates from the UK. Of 73 clinical isolates identified as N. asteroides from different parts of England and Wales during 1991-1993, and now subjected to further differentiation tests by the Mycobacterial/Nocardial Reference Laboratory, 15 (20.5%) were identified as N. farcinica based on three out of four characteristics: growth property, acetamide production, rhamnose assimilation and a distinct antibiogram. No isolates were identified as N. nova. A revised identification and susceptibility system has significant clinical and taxonomic implications. Its introduction will improve speciation, identify antibiotic resistance and influence the choice of safer alternative therapy for patients infected with Nocardia spp. in the UK.

Urinary tract infections in primary biliary cirrhosis and other chronic liver diseases.

In a study to determine the prevalence of urinary tract infections (UTI) in primary biliary cirrhosis, midstream specimens of urine from 97 females with primary biliary cirrhosis and 85 females with other chronic liver diseases were investigated prospectively for urinary pathogens and Mycobacterium gordonae. No significant differences between primary biliary cirrhosis and the two groups were observed in the prevalence of significant bacteriuria (11.3% vs. 7.1%), the prevalence of Escherichia coli UTI (9.3% vs. 7.1%) or the colony morphology of Escherichia coli. No mycobacterial species were grown from any sample. In both groups, the prevalence of UTI was higher in patients with cirrhosis (20% in both) than in those without.

Randomised placebo-controlled trial of granulocyte-colony stimulating factor in diabetic foot infection.

BACKGROUND: Diabetic foot infections cause substantial morbidity and mortality. Neutrophil superoxide generation, a crucial part of neutrophil bactericidal activity, is impaired in diabetes. Granulocyte-colony stimulating factor (G-CSF) increases the release of neutrophils from the bone marrow and improves neutrophil function. We assessed G-CSF as adjuvant therapy for the treatment of severe foot infections in diabetic patients. METHODS: 40 diabetic patients with foot infections were enrolled in a double-blind placebo-controlled study. On admission, patients were randomly assigned G-CSF (filgrastim) therapy (n = 20) or placebo (n = 20) for 7 days. Both groups received similar antibiotic and insulin treatment. Neutrophils from the peripheral blood of these participants and from healthy controls were stimulated with opsonised zymosan, and superoxide production was measured by a spectrophotometric assay (reduction of ferricytochrome C). FINDINGS: G-CSF therapy was associated with earlier eradication of pathogens from the infected ulcer (median 4 [range 2-10] vs 8 [2-79] days in the placebo group; p = 0.02), quicker resolution of cellulitis (7 [5-20] vs 12 [5-93] days; p = 0.03), shorter hospital stay (10 [7-31] vs 17.5 [9-100] days; p = 0.02), and a shorter duration of intravenous antibiotic treatment (8.5 [5-30] vs 14.5 [8-63] days; p = 0.02). No G-CSF-treated patient needed surgery, whereas two placebo recipients underwent to amputation and two had extensive debridement under anaesthesia. After 7 days' treatment, neutrophil superoxide production was significantly higher in the G-CSF group than in the placebo group (16.1 [4.2-24.2] vs 7.3 [2.1-11.5] nmol per 10(6) neutrophils in 30 min; p < 0.0001). G-CSF therapy was generally well tolerated. INTERPRETATION: G-CSF treatment was associated with improved clinical outcome of foot infection in diabetic patients. This improvement may be related to an increase in neutrophil superoxide production.

Risk of fetal infection from invasive procedures.

Recent technological advances have led to the development of several types of invasive procedures in the fetus principally for the diagnosis and management of fetal disorders. The risk of infection to the fetus related to these procedures needs evaluation. Although there are few reports of fetal infection, proper infection control procedures must be observed because the most common consequence of infection is fetal loss. Fetal blood sampling in the presence of chorioamnionitis is a risk factor that warrants prophylactic antibiotics. Conversely, clinical specimens taken from the fetus in the absence of chorioamnionitis are more likely to become contaminated with maternal skin flora, and a positive fetal blood culture is not necessarily significant. There is probably a small but finite risk of transmission of maternal viral infections such as human immunodeficiency virus, hepatitis B and C, cytomegalovirus and herpes simplex during invasive procedures. Obstetric departments undertaking invasive fetal diagnosis and treatment must have an adequate policy for infection control procedures.

Bacterial and fungal infection in acute liver failure.

Patients with acute liver failure (ALF) have increased susceptibility to infections, principally as a result of impaired phagocytic function, reduced complement levels, and the need for invasive procedures. Bacteriologically proven infection is recorded in up to 80% of these patients and fungal infection (predominantly candidiasis) in 32%. Clinical signs such as high temperature and high WBC are absent in 30% of the cases. Pneumonia accounts for 50% of infective episodes, and bacteremia and urinary tract infection a further 20 to 25% each, at a median 5, 3, and 2 days, respectively, after the onset of ALF. Selective parenteral and enteral antisepsis regimens (SPEAR) were evaluated in prospective controlled studies, but early systemic antibiotics alone are as effective as SPEAR. With early antibiotics, the incidence of infective episodes is reduced to 20% and the overall mortality to 44%, with a reduction in progression to encephalopathy and an increased opportunity for transplantation.

Prevention of fungal infections in hematology patients.

Endogenous infections such as candidiasis can be minimized by oral fluconazole prophylaxis, although oral or intravenous amphotericin, or itraconazole, are suitable for certain patients. Exogenous fungal infections most commonly are transmitted by the airborne route, but the benefits of high-efficiency particulate air-filtered room air probably are diminishing as broad-spectrum prophylaxis against Aspergillus species and other fungi improves. However, high-risk environmental sources such as construction work always must be avoided near neutropenic patients. Reactivation of quiescent pulmonary Aspergillus infection can be prevented by surgical resection during remission, or by systemic amphotericin prophylaxis during subsequent neutropenic episodes.