Nosocomial cross transmission as a primary cause of vancomycin-resistant enterococci in Austria

Stool specimens from 226 patients from intensive care units (N=69), general wards (N=112), and outpatient-clinics (N=45) at the Innsbruck University Hospital and from 433 healthy volunteers were inoculated on to Enterococcosel Agar supplemented with 5 microg/mL vancomycin and 4 microg/mL cefodizime. Faecal specimens from 105 dairy cows, 171 pigs and 47 egg-laying hens were processed the same way. Thirteen of 226 patients (5.8%) harboured 14 vancomycin-resistant enterococci (VRE) of the vanA genotype; 12 E. faecium (from 11 patients) and two E. faecalis (ICU patients: 5.8%, general ward patients: 5.4%, outpatients: 6.7%). None of the faecal specimens from healthy volunteers or animals yielded VRE. Nine of the 13 patients harbouring VRE had received antibiotic therapy during the previous four weeks (broad-spectrum cephalosporins: six patients; i.v. vancomycin: five patients). Of the 14 VRE (vanA type) isolates six strains were indistinguishable by PFGE using Sma I as restriction endonuclease, six strains formed three pairs, and only two single isolates showed unique patterns. The results of our study supports the view that nosocomial cross transmission is currently the main cause of colonization and infection with VRE in Austria.

Epstein-Barr virus-associated Hodgkin's lymphoma and legionella pneumophila infection complicating treatment of juvenile rheumatoid arthritis with methotrexate and cyclosporine A

We describe the case of a 53-month-old girl with juvenile rheumatoid arthritis (JRA), complicated by the occurrence of Hodgkin's lymphoma and Legionella pneumophila infection during immunosuppressive treatment with methotrexate (MTX) and cyclosporine A (CSA). The girl had received variable anti-inflammatory combination therapy, including MTX for 28 months and CSA for 3 months. Thirty-six months after the onset of arthritis, the girl presented with an enlargement of the lymph nodes of the mediastinum, the hilum of the lungs, and the abdomen. Concomitantly, a diagnosis of Legionella pneumonia was rendered. Autopsy showed Epstein-Barr virus (EBV)-associated nodular sclerosing Hodgkin's lymphoma. The neoplastic cells were positive for CD15, CD 30, and latent membrane protein 1 (LMP 1). The present case is the second reported to occur in a child, and it lends support to the hypothesis that immunosuppressive treatment may contribute to an increased risk of the development of EBV-associated lymphoproliferative disorders (LPD) in pediatric patients suffering from JRA.

Simultaneous infection with two drug-susceptible Mycobacterium tuberculosis strains in an immunocompetent host

An important assumption for DNA fingerprinting of Mycobacterium tuberculosis is that patients are infected with only one strain at a time. Nonetheless, we demonstrate a case of simultaneous infection with two drug-susceptible strains of M. tuberculosis in an immunocompetent patient by IS6110 restriction fragment length polymorphism and spoligotyping. Epidemiological data prove the patient's involvement in two independent clusters. Thus, double infections should be suspected with fingerprints showing divergent band intensities.

Enterohemorrhagic Escherichia coli (EHEC) in pediatric hemolytic-uremic syndrome: a prospective study in Germany and Austria

Studies from Europe indicate that infections with enterohemorrhagic Escherichia coli (EHEC) non-O157:H7 strains are increasing in frequency as a cause of hemolytic-uremic syndrome (HUS). In 1997 a prospective study was performed in Germany and Austria to assess the distribution of EHEC serotypes, to characterize the clinical course and to examine environmental aspects. 95 children with a diagnosis of HUS were evaluated in Germany and Austria. Diarrhea, which was bloody in 67%, was reported in 97% of patients. Oligo-/anuria occurred in 76% of patients, of which 63% required dialysis. Two patients showed neurological sequelae at the 2-month follow-up, both of them were infected with non-O157:H7 serotypes. Case fatality in the acute stage was 3/95, in two of these patients EHEC was isolated. Stool and serum specimens were analyzed for the presence of EHEC and antibodies against O157 lipopolysaccharide (LPS). Serotype O157:H7 was identified in 36/58 (62%) isolates, 22 strains (38%) belonged to non-O157:H7. Combining stool culture with serology, EHEC infection was documented in 88% of patients, including three patients without diarrhea. Non-O157:H7 serotypes occurred in 77% of children up to 36 months of age and were the most prevalent serotype in children up to 12 months of age.

Molecular characterisation of verocytotoxin-producing Escherichia coli of serogroup O111 from different countries

A collection of epidemiologically unrelated verocytotoxin (VT)-producing Escherichia coli (VTEC) strains of serogroup O111 isolated from human patients and cattle with diarrhoeal disease in five different countries were characterised by determination of their VT genotypes, the presence of other virulence factors such as the intimin-coding eae gene and the enterohaemorrhagic E. coli (EHEC) plasmid, and their antibiotic susceptibility patterns. The genetic relatedness among isolates was evaluated by genomic DNA fingerprinting techniques such as restriction fragment length polymorphism analysis of ribosomal RNA genes (ribotyping) and pulsed-field gel electrophoresis. The results indicated that the VTEC O111 examined belong to two distinct clonal lineages. The first group was constituted mainly of non-motile, eae-positive, EHEC plasmid-positive isolates from both man and cattle. The second lineage was represented by an O111:H2 epidemic strain, isolated during an outbreak of haemolytic uraemic syndrome in France and exhibiting an unusual combination of virulence factors: VT production and aggregative adhesion to HEp-2 cells associated with an enteroaggregative E. coli (EAEC) plasmid.

Sporadic infection caused by enterohemorrhagic d Escherichia coli O157

In 1997 the Austrian Federal Ministry of Health established a reference laboratory for enterohaemorrhagic Escherichia coli at the federal public health laboratory in Innsbruck. The reference laboratory investigates sources of infection causing food poison

Bactericidal activity of vancomycin in cerebrospinal fluid

Intraventricular application of vancomycin is an effective therapeutic regimen for the treatment of shunt-associated staphylococcal ventriculitis. We examined the in vitro activity of vancomycin at high concentrations against Staphylococcus aureus ATCC 25923 and Staphylococcus epidermidis ATCC 12228 in human cerebrospinal fluid samples. Time-kill curves revealed equal efficacies for concentrations of 10, 100, and 300 microg/ml, and incubation times of 24 to 48 h were needed to achieve a 3 log(10) reduction of viable bacteria. A concentration of 5 microg/ml showed a slightly lower activity, but this difference was not significant. In an infant who was successfully treated for shunt-associated ventriculitis due to S. epidermidis by once-daily local administration of vancomycin (3 mg for 2 days and 5 mg for 4 days [0. 5 to 0.8 mg/kg of body weight]) the in vivo kill kinetics were similar to those for the in vitro results. These results support time-dose regimens that provide trough vancomycin levels of 5 to 10 microg/ml.

In vitro activity of newer broad spectrum beta-lactam antibiotics against enterobacteriaceae and non-fermenters: a report from Austrian intensive care units. Austrian Carbapenem Susceptibility Surveillance Group

We compared the in vitro activity of broad spectrum beta-lactam antibiotics against 573 gram-negative isolates (enterobacteriaceae and non-fermenters) collected between November 1996 and May 1997 from 9 laboratories serving intensive care units throughout Austria. MIC's (Minimal Inhibitory Concentration) were obtained with the E-test for meropenem, imipenem, ceftazidime, cefepime, cefpirome and piperacillin/tazobactam. Pseudomonas aeruginosa was the most frequently isolated organism (22%), followed by E. coli (19%), Klebsiella spp. (16%), and Enterobacter spp. (14%). Acinetobacter spp., Proteus spp., Serratia spp., Stenotrophomonas maltophilia, Citrobacter spp., Morganella morganii, Burkholderia cepacia and Salmonella enteritidis were isolated less frequently. Overall meropenem, imipenem and ceftazidime were the most active compounds in vitro, inhibiting 90%, 89%, and 87% of the isolates, respectively. Pseudomonas aeruginosa was inhibited by piperacillin/tazobactam in 89%, by cefepime in 87% and by ceftazidime in 85%. Imipenem, meropenem and cefpirome were less active (79%, 75% and 69% respectively). All E. coli strains were inhibited by meropenem, 99% were inhibited by imipenem, cefepime and cefpirome. Ceftazidime was active against 95% and piperacillin/tazobactam against 92% of E. coli. All Klebsiella spp. were inhibited by meropenem, cefepime and cefpirome. Imipenem inhibited 99% and ceftazidime 98% of the Klebsiella isolates. Piperacillin/tazobactam was active against 95% of Klebsiella spp. In vitro carbapenems are still the most active of all antibiotics tested. The relatively high resistance of Pseudomonas spp. and Acinetobacter spp. to carbapenems reflects the wide use of carbapenems during the last years. However, most bacterial isolates are still sensitive to the tested broad spectrum beta-lactams.

Trends in infection morbidity in a pediatric oncology ward, 1986-1995

BACKGROUND AND PROCEDURE

We retrospectively studied the type, severity, frequency, and outcome of febrile infectious complications in 217 cancer patients receiving cytotoxic chemotherapy (603 episodes) over a 10-year period in a single pediatric institution.

RESULTS

A total of 48.8% of the episodes occurred in severely leukopenic patients (WBC < 1.0 x 10(9)/l, absolute neutrophil count < 500 x 10(6)/l). In the second half of the study period febrile episodes occurred at increased frequency. The number of patients with gram-positive isolates in blood cultures increased over the years, most frequently coagulase-negative staphylococci were found. Remarkably, gram-negative bacteria increasingly resistant to the administered first-line antibiotic regimen emerged, necessitating modifications of the antimicrobial strategy every 3 years. Furthermore, Clostridium difficile-associated enterocolitis posed a clinical problem at increasing frequency since 1993. As expected, the speed of leukocyte recovery within 5 days from the onset of a febrile complication had an influence on the outcome of these episodes.

CONCLUSIONS

Rapid recovery of the WBC was associated with an excellent prognosis whereas persisting neutropenia was found to be a negative factor associated with fatal outcomes. The fatality rate of all febrile episodes (2.3%) remained the same throughout the study period despite the availability and wider use of recombinant hematopoietic growth factors since 1991.

Antibacterial activity of gentamicin and ciprofloxacin against Gram-negative bacteria: interactions with pig and calf sera

The antibacterial activity of pig and calf serum and its ability to interact with gentamicin and ciprofloxacin were studied in vitro using Escherichia coli K-12, Proteus rettgeri (Sanelli) and Klebsiella pneumoniae ATCC 10031. The antimicrobial activity of the above drugs, alone or in combination with serum, was investigated by the checkerboard method and expressed as the minimal inhibitory concentration (microg ml-1). Pig serum (25%) with gentamicin had a synergistic antibacterial effect against Escherichia coli K-12 and pig serum (25%) with ciprofloxacin against Proteus rettgeri (Sanelli) and Klebsiella pneumoniae ATCC 10031. Calf serum (25%) had a synergistic effect with gentamicin against Proteus rettgeri (Sanelli) and calf serum (25%) plus ciprofloxacin against Klebsiella pneumoniae ATCC 10031. The effects of these drugs may be enhanced by pig and calf sera.

Use of automated ribotyping of Austrian Listeria monocytogenes isolates to support epidemiological typing

We used automated ribotyping on the RiboPrinter Microbial Characterization System to study the epidemiology of listeriosis in western Austria over the period 1988-1996. Thirty-six isolates containing three serotypes were included in this collection. Each of the 16 ribotype groupings (RiboGroups) produced in this study contained a single serotype. Isolates collected from within a single food factory environment all grouped into unique RiboGroups. One factory contained isolates showing two unique RiboGroups, both of which were also seen in patient isolates. This same set of Listeria isolates has previously been studied by automated laser fluorescence analysis of randomly amplified polymorphic DNA (RAPD-Alfa). The data produced by the RiboPrinter system correlated well with the epidemiological information, better than the results achieved with RAPD-Alfa. The RiboPrinter system provides a rapid, easy, and useful method for the typing of Listeria monocytogenes.

In-vitro activity of fosfomycin against vancomycin-resistant enterococci

The effect of fosfomycin against 69 vancomycin-resistant isolates of Enterococcus faecium (VanA), five of E. faecium (VanB), 11 of Enterococcus faecalis (VanA), three of E. faecalis (VanB), 10 of Enterococcus gallinarum (VanC1) and two of Enterococcus casseliflavus (VanC2) and glycopeptide-sensitive E. faecium (n = 8) and E. faecalis (n = 10) was tested in vitro. Fosfomycin inhibited 97%, 94% and 96% of the vancomycin-resistant strains, according to results of agar dilution, broth microdilution, and a disc diffusion method (DIN 58940). The disc diffusion test by the NCCLS method does not include fosfomycin; using breakpoints suggested by Andrews et al. (< or = 11 mm, resistant; > or = 18 mm, susceptible), 5% of the vancomycin-resistant strains tested would have been considered fosfomycin resistant. Minimal inhibitory concentrations of most vancomycin-resistant isolates were in the intermediate sensitivity range, yielding an MIC50 of 32 mg/L and an MIC90 of 64 mg/L. Moreover the majority of inhibitory zone sizes by the disc diffusion method (DIN 58940) corresponded to intermediate susceptibility. These results suggest that fosfomycin at a high dosage and possibly used in combination with other drugs could be a potentially useful drug for the treatment of infections caused by vancomycin-resistant enterococci.

Strain-specific differences in the amount of Shiga toxin released from enterohemorrhagic Escherichia coli O157 following exposure to subinhibitory concentrations of antimicrobial agents

There is no consensus regarding the benefit versus harm of antibiotic therapy for treatment of disease due to enterohemorrhagic Escherichia coli O157. The effects in vitro of subinhibitory concentrations of 13 antimicrobial agents on the release of Shiga toxin (Stx) by three different Escherichia coli O157 strains expressing Stx 1 or Stx 2 either alone or in combination were investigated. The Stx-induced cell death of Vero cells was determined using a colorimetric assay based on the measurement of lactate dehydrogenase (LDH) released into the supernatant from the cytosol of damaged cells. Growth of all O157 strains in broth cultures containing subinhibitory concentrations of cotrimoxazole, trimethoprim, azithromycin, or gentamicin was accompanied by a marked increase in the release of Stx. Exposure to cefixime, ceftriaxone, or erythromycin caused a marked increase in the release of Stx by the O157 strain producing Stx 2 alone, but decreased toxin production was observed with the Stx 1 producer and the strain producing Stx 1 and Stx 2. Exposure to ampicillin caused increased Stx release in the Stx 2-producing strain but had no effect on Stx production in the other two test isolates. Exposure to penicillin G, streptomycin, ciprofloxacin, fosfomycin, or sulfamethoxazole caused an increase in toxin production in two of the three test strains in each case, while decreases were observed for the other isolates. The response of Escherichia coli O157 isolates to subinhibitory concentrations of antibiotics seems to be highly dependent on the nature of the strain involved.

Comparative study of five different techniques for epidemiological typing of Escherichia coli O157

A set of 47 Austrian human, food, and veterinary Escherichia coli O157:H7 isolates was used to evaluate five different epidemiological typing methods. Ribotyping using an automated microbial characterization system (RiboPrinter) was not suitable for detection of epidemiological relatedness. All but one E. Coli strain were typeable by phage typing. Random amplified polymorphic DNA-PCR fingerprinting was performed using primer M13 containing the sequence 5'-GAG GGT GGC GGT TCT-3' and primer 1247 (5'-AAGAGCCCGT-3'). Although both methods recognized only two clusters, both dendrograms grouped most of the EHEC O157 isolates into epidemiologically related subgroups. Pulsed-field gel electrophoresis of XbaI digested total DNA was a valuable subtyping system. We found that major differences can exist between results of multiple subtyping methods. E. coli O157 isolates should not be classified as epidemiologically related or nonrelated on the basis of a single typing method alone.

Antibacterial activity of human pleural fluid: alone and in combination with antibiotics

This study investigated the antibacterial activity of human pleural fluid (HPF) and its interaction with gentamicin (GM), meropenem (MRPM), ciprofloxacin (CPFX) and clarithromycin (CLTM) against Escherichia coli K-12, Proteus rettgeri (Sanelli) and Staphylococcus aureus. Minimal inhibitory concentrations or volumes, expressed as MIC or volume percentage (MIV, V/V%), were measured using a micro-dilution technique in microtiter plates. The antimicrobial activity of HPF combinations with antimicrobial drugs was evaluated by the chequerboard method calculating the fractional inhibitory concentration index (FIC) values. HPF MIVs (%) were: 37.54; 19.85; 1.74 for E. coli, P. rettgeri and S. aureus, respectively. FIC values indicated a synergistic effect with GM, MRPM and CPFX against E. coli and P. rettgeri and an additive effect for the combination HPF plus CLTM or indifference with HPF plus GM and CPFX against S. aureus. The presence of antibodies, complement factors, lysozyme, alpha-defensins and enzymes could explain the antimicrobial activity of HPF and its synergistic effect with certain antibiotics.

[Imipenem resistance in Pseudomonas aeruginosa]

In 1997 in western Austria, 9.9% of Pseudomonas aeruginosa strains from patients of general practitioners were resistant to imipenem as well as 18.2% of the isolates from hospitals and 20.2% of the strains at a university teaching hospital. Within the hospital the imipenem resistance varied from 9.9% among out-patients to 28.7% in isolates from intensive care units. In medical/surgical words, up to 15.1% of P. aeruginosa strains were resistant to imipenem. The incidence of imipenem-resistant P. aeruginosa strains correlates to the use of carbapenems. In June 1997, 10 consecutive isolates from 8 patients were obtained and typed using restriction fragment length polymorphism analysis (RFLP) and Pyocin typing. All 10 isolates were resistant to meropenem as well as to imipenem. The finding (by RFLP and Pyocin typing) of individual bacterial types in each isolate strongly contradicts the spread of infection by cross infection. However, all patients were proven to have been treated with imipenem during the 3 months prior to testing. In 1997, 13,880 g of imipenem were used at the university hospital in Innsbruck. The use of carbapenems appears to be the main cause for the increased incidence of imipenem-resistant P. aeruginosa strains.

E-test for susceptibility testing of Mycobacterium tuberculosis

SETTING

Initial isolates should be tested for drug susceptibility to confirm the anticipated effectiveness of chemotherapy.

OBJECTIVE

To evaluate E-test strips for susceptibility testing of Mycobacterium tuberculosis.

DESIGN

A proportion method using Lowenstein-Jensen medium and the Bactec radiometric system were compared with the E-test (isoniazid [INH], rifampicin [RMP], ethambutol [EMB] and streptomycin [SM]).

RESULTS

For 73 of the 81 M. tuberculosis isolates (90.1%) the proportion and E-test methods yielded concordant susceptibility results against all four antimicrobial agents tested. Of these 73 strains, 69 were fully susceptible; the four isolates showing resistance to antimicrobial drugs by both methods were also resistant when tested by Bactec 460TB. While the proportion method indicated susceptibility for the eight remaining strains, E-test results showed mono EMB resistance in five strains, INH resistance for two isolates (including one isolate resistant to EMB plus INH), and for one strain E-test yielded resistance to EMB and SM. Using Bactec as the reference method, the E-test resulted in false resistance in eight strains and no false susceptibility.

CONCLUSION

Due to a substantial rate of false resistance, this method cannot be recommended at present for practical use in clinical laboratories.

Changing bacterial ecology during a five-year period of selective intestinal decontamination

The development of bacterial resistance during selective decontamination of the digestive tract (SDD) is controversial. We studied effects on bacterial resistance one year before and during a randomized, placebo-controlled trial of SDD in a surgical intensive care unit. We randomized patients within two different topical regimens (PTA, PCA) or placebo, administered four-times daily to both the oropharynx and gastrointestinal tract. All patients received intravenous ciprofloxacin (200 mg b.d.) for four days. Both SDD regimens successfully reduced aerobic Gram-negative intestinal colonization. There was no increase in resistance of Enterobacteriaceae or Pseudomonas aeruginosa. Acinetobacter calcoaceticus developed multi-resistance over one year, but differences between groups were not significant. We detected a shift towards Gram-positive organisms. Oxacillin-resistant Staphylococcus aureus increased in concert with ciprofloxacin resistance, from 17 to 80.7%, and frequencies of resistance were significantly higher in SDD patients (P < 0.001). Resistance of coagulase-negative staphylococci (CNS) to oxacillin increased initially (25 to 66.9%), but values returned to baseline in controls. Ciprofloxacin resistance in CNS remained higher (P < 0.001) in SDD-treated patients (52.5 vs. 23.3%). The incidence of late respiratory tract infections was unaltered by the prophylactic regimen (SDD 35.2%; Placebo 41.2%; n.s.). We cannot recommend SDD as a prophylactic tool in critically ill patients.

Domestic pets as risk factors for alveolar hydatid disease in Austria

To identify the risk of pet ownership (i.e., cats and dogs) for alveolar echinococcosis caused by Echinococcus multilocularis, the habits and activities of 21 patients (histologic confirmation or positive serology with corresponding evidence on an ultrasonogram, radiograph, or computed tomography scan) in Austria during the period 1967-1997 were compared with the habits and activities of 84 controls matched by sex, age, and residence. Cat ownership (odds ratio (OR) = 6.47, 95% confidence interval (CI) 1.54-27.29) and hunting (OR = 7.83, 95% CI 1.16-52.77) were independent risk factors associated with alveolar hydatid disease. The study is not in agreement with the hypothesis that eating mushrooms or certain wild berries which grow near the ground are the main risk factors for acquiring this disease. No other behavior patterns or activities studied were identified as risk factors.

Antibacterial activity of peritoneal exudate in patients treated with 2 g cefotiam for surgical anti-microbial prophylaxis

The objective of this study was to investigate the presence of antibacterial activity in peritoneal exudate (PE) of patients treated with cefotiam (CFT). CFT (2 g) was administered as a 'single-shot' antimicrobial prophylaxis to 6 patients at the beginning of colorectal resection. Samples of PE were collected from each patient on days 1, 2 and 3 after surgery. CFT was detectable in the samples of day 1 for 5 of the 6 patients. The influence of PE on antibacterial activity of the antimicrobial drug was evaluated carrying out the MICs of CFT against Escherichia coli K-12, E. coli (ATCC 10798), Klebsiella pneumoniae (ATCC 1003), Proteus rettgeri (Sanelli) and Staphylococcus aureus (ATCC 29213) with and without the addition of PE. The presence of PE enhanced the antimicrobial activity of CFT against gram-negative strains, but not against S. aureus (ATCC 29213). These results suggest the presence of substances in PE that possess endogenous antibacterial activity. Thus, antimicrobial activity in PE cannot be predicted by evaluating pathogen sensitivity in vitro only.