Cross-resistance patterns among clinical isolates of Klebsiella pneumoniae with decreased susceptibility to cefuroxime.

The frequency of decreased susceptibility to cefuroxime and quinolones and the correlation between these drug resistance traits was investigated in clinical isolates of Klebsiella pneumoniae from two Danish counties. Eighty-three randomly selected clinical isolates of K. pneumoniae with decreased susceptibility to cefuroxime were examined for cross-resistance patterns and the production of beta-lactamases. The frequency of resistance to cefuroxime and ciprofloxacin has increased from <5% in 1990 to 15% and 7% in 1998, respectively. Two of the 83 isolates were multiply resistant and seemed to produce extended-spectrum beta-lactamases. However, cross-resistance to ciprofloxacin and other classes of drug in 68% of the remaining isolates indicates that other resistance mechanisms, such as penetration barriers, had probably been selected in these Danish isolates. The susceptibility to ciprofloxacin decreased successively with decreasing susceptibility to cefuroxime for K. pneumoniae. This did not occur in cefuroxime-resistant Escherichia coli.

Risk factors for hospital-acquired Staphylococcus aureus bacteremia.

BACKGROUND: Staphylococcus aureus bacteremia (SAB) acquired in hospitals continues to be a frequent and serious complication to hospitalization, and no previous case-control studies dealing with risk factors of this severe disease are available. METHODS: Based on a 1-year prospective analysis, the data from all patients with hospital-acquired SAB admitted to 4 hospitals in Copenhagen County, Denmark, from May 1, 1994, through April 30, 1995, were evaluated. Eighty-five patients with hospital-acquired SAB were matched to 85 control patients with a similar primary diagnosis at admission (matched controls). Of these, 62 patients with hospital-acquired SAB were compared with 118 other patients with a similar time of admission, who were randomly selected with no clinical evidence of SAB (unmatched controls). RESULTS: The incidence of hospital-acquired SAB was 0.71 per 1000 hospital admissions. The presence of a central venous catheter (odds ratio, 6.9; 95% confidence interval [CI], 2.8-17.0), anemia (odds ratio, 3.3; 95% CI, 1.4-7.6), and hyponatremia (odds ratio, 3.3; 95% CI, 1.5-7.0) was significantly associated with hospital-acquired SAB in a conditional and a usual logistic regression analysis. Nasal carriage was not an independent risk factor, but nasal carriers among patients in surgery (odds ratio, 4.0; 95% CI, 1.3-13.0) had a significantly higher risk for hospital-acquired SAB compared with matched and unmatched controls. The presence of hospital-acquired SAB increased the mortality rate 2.4-fold (95% CI, 1.1-5.2). CONCLUSIONS: The presence of a central venous catheter is an important risk factor, and hyponatremia and anemia are associated with the development of hospital-acquired SAB. Furthermore, hospital-acquired SAB in itself increases mortality.

Gastric mucosal interleukin-8 and IL-8 antibody concentrations related to prevailing Helicobacter pylori infections. A Danish-Albanian study.

OBJECTIVES: Helicobacter pylori (H. pylori) appears to initiate an inflammatory cascade. Thus, phagocytes are accumulated in the gastric mucosa, in inflammatory conditions. Further, a potent chemotactic mediator, interleukin 8 (IL-8) is synthesized at such sites. The recently described IL-8 autoantibodies may, however, counteract the pro-inflammatory actions of IL-8. The aim was to study the correlation between H. pylori infection and IL-8, together with IL-8 autoantibodies in two different populations from a developed and a developing country. METHODS: Two different endoscopically characterized populations (65 Danes and 89 Albanians) were examined. IL-8 and IL-8 autoantibodies were detected by ELISA techniques, and H. pylori was identified by histological examinations. RESULTS: Significantly more Albanian controls and dyspeptic patients (80 out of 89 persons) were H. pylori positive as compared to 24 of 65 Danes (p < 0.001). The median IL-8 level among Albanian controls 349 pg/mg protein was significantly higher than among Danes < 61 pg/mg protein (p < 0.001), and was at the same level as found in Danish peptic ulcer patients (p > 0.05). Further, H. pylori positive patients from both countries had significantly higher levels of IL-8 as compared to H. pylori negative patients (p < 0.001). However, significantly higher levels of IL-8 autoantibodies were found in the Albanian sub-population (median 138 O.D. units versus 52 O.D. units among Danes) (p < 0.001). CONCLUSIONS: In H. pylori related disorders, a high mucosal IL-8 production has been found. However, this investigation further demonstrates higher levels of IL-8 autoantibodies among dyspeptic patients from a developing country, which might possibly counteract the pro-inflammatory actions of IL-8 by binding the molecule. The physiological significance of an altered immune response as described here needs to be elucidated in future studies.

Helicobacter pylori detection in human biopsies: a competitive PCR assay with internal control reveals false results.

A polymerase chain reaction assay (PCR) for the diagnosis of Helicobacter pylori in human gastric biopsies was developed. To prevent false-negative results while performing PCR on human tissues, an internal control is necessary. Primer set ACT1-ACT2 which specifically amplifies a 542-bp fragment of the 16S rRNA gene of H. pylori was used. dUTP and hot-start were used to prevent false-positives from carryover of previous products and avoid non-specific extension products. A competitive internal control DNA fragment was constructed to detect the presence of inhibitors. Biopsies from 101 unselected patients with gastric symptoms were tested. PCR results were compared with results from microscopy of histological sections and conventional culturing for H. pylori. Forty-two percent of the biopsies were found to contain compounds inhibiting the PCR. The addition of the internal control assures the performance of the PCR assay and is an important quality control parameter.

An analysis of seven different methods to diagnose Helicobacter pylori infections.

BACKGROUND: It has been debated which diagnostic test should be preferred for the diagnosis of Helicobacter pylori in patients with gastroduodenal diseases. METHODS: The H. pylori infection was diagnosed prospectively in 97 untreated patients. H. pylori was diagnosed by means of tests based on five different principles: 1) culture, 2) microscopy (HLO), 3) urease activity (urea breath test (UBT) and urease test on biopsy specimens (CLO test)), 4) DNA detection (polymerase chain reaction (PCR)), and 5) IgG antibody detection (enzyme-linked immunosorbent assay (EIA) and Western blotting (WB)). RESULTS: This study showed that two positive tests out of five tests, based on different principles, were most reliable for predicting the H. pylori infection. Most tests had specificities and predictive values for a negative result greater than 90%. The most important difference between the tests was the sensitivity and the predictive value for a positive result (PPV). WB, HLO, UBT, and PCR had sensitivities and PPV greater than 75%. CONCLUSIONS: The non-invasive tests UBT and WB are reliable, both alone and in combination, and they are recommended for the pre-endoscopic diagnosis of H. pylori. WB is recommended as a confirmative test for antibody detection by EIA. When patients have an upper endoscopy, we recommend taking biopsy specimens for culture and histology because of the additional information obtained about susceptibility, virulence determinants, and morphology, including the degree of inflammation.

[Penicillin resistant pneumococci--not a threat in Denmark yet?]. / Penicillinresistente pneumokokker--endnu ikke en trussel i Danmark?

The occurrence of penicillin resistance in clinical isolates of pneumococci was investigated in two clinical microbiological laboratories in Copenhagen, Denmark. One of the laboratories predominantly received samples from patients with frequent use of antibiotics mainly because of chronic lung diseases. In this laboratory, 6.3% of 245 isolates of pneumococci had intermediate resistance to penicillin. In the other laboratory, which received samples from a number of hospitals and general practice, only 1.3% of isolates of pneumococci had reduced sensitivity to penicillin. Penicillin-resistant pneumococci are rare in Denmark, but are more prevalent in patients who frequently use antibiotics.

Cefuroxime resistance in Klebsiella pneumoniae. Susceptibility to cefotaxime and ceftazidime despite production of ESBLs.

The production of beta-lactamases, the outer membrane protein (OMP) patterns, some clinical impacts and the prevalence of resistance among cefuroxime-resistant Danish clinical isolates of Klebsiella pneumoniae were investigated. Fifteen resistant and five susceptible strains were collected from 14 patients during 1991-1994. Isolates from five patients produced extended-spectrum beta-lactamases (ESBLs). Cefuroxime resistance was accompanied by a 10-fold elevation of ciprofloxacin minimal inhibitory concentration (MIC), and for some isolates by an alteration of the OMP pattern. The relationship between alterations of the OMP patterns and cross-resistance to ciprofloxacin and the other antibiotics tested was not universal. Ten of the cefuroxime-resistant strains had elevated MICs of cefotaxime or ceftazidime, but the MICs were still below the breakpoint for susceptibility. The MICs of imipenem were not affected. Nosocomial infection or long-term colonization with resistant strains may be of importance since five patients were not treated with cefuroxime prior to isolation of the resistant strain, and all patients had either serious diseases or stayed at the hospital for a long period of time. The prevalence of cefuroxime and ciprofloxacin resistance among clinical isolates from Copenhagen county during 1990-1995 was 8.3% and 7.5%, respectively, but higher for urinary tract specimens. A greater consumption of cefuroxime as compared to cefotaxime and ceftazidime in this study, as seen generally in Denmark, indicated that ESBLs produced by the investigated strains of K. pneumoniae may be selected with cefuroxime.

[Penicillin treatment of non-nosocomial pneumonia in Danish medical departments. A questionnaire]. / Penicillinbehandling af ekstranosokomielt erhvervet pneumoni på medicinske afdelinger i Danmark. En spørgeskemaundersøgelse.

This study describes the most common penicillin-regime for hospitalized patients with community-acquired pneumonia in Denmark. One hundred and seventy-one consultant physicians received an anonymous questionnaire, 85% were returned and 75% were evaluated. The most common regime is a treatment duration of six to ten days with 3-6 million IU of penicillin daily given in three doses. The most common route of administration is intravenously until the patient's body temperature drops. Then the same dose is given orally. Variations in strategy were revealed and call for further investigations to establish and maintain restrictive antibiotic regimes.

[Extraintestinal Salmonella infections in four Danish counties. Inverse relationship between invasiveness and zoonotic serotypes]. / Ekstraintestinale Salmonella-infektioner i fire danske amter. Invers relation mellem invasivitet og incidens af zoonotiske serotyper.

The relationship between invasiveness and incidence of non-typhoid salmonellosis was ascertained retrospectively in a population of 1.9 million in four Danish counties during the three-year period 1992-1994. The study comprised 4175 cases diagnosed by culture either locally or at Statens Serum Institut, Copenhagen. Two hundred and forty-four patients had extraintestinal infections caused by 24 out of the total number of 101 different serotypes. Invasiveness ranged widely from 4% to > 90% for individual serotypes. Salmonella typhimurium and Salmonella enteritidis formed a high-incidence group (incidence rates > or = 25/100,000/year) compared to the remaining 22 serotypes (< 5/100,000/year). The low-incidence group was more invasive than the high-incidence group even when excluding Salmonella dublin, which is highly invasive, and including 212 cases of salmonelloses caused by serotypes isolated entirely from faeces (relative risk 1.54, 95% confidence limits 1.19 < RR < 2.00). The data corroborate a previous more limited study and indicate that previous exposure to salmonella and acquired immunity may play a role in the occurrence of extraintestinal non-typhoid salmonellosis.

[Spondylitis and medullary transverse syndrome caused by Staphylococcus aureus]. / Spondylit og medullaert tvaersnitssyndrom forårsaget af Staphylococcus aureus.

Three cases of haematogenous osteomyelitis in the vertebral column caused by Staphylococcus aureus are reported. The cases, which were associated with severe neurological symptoms and/or death, were initially characterized by a long period with no or discrete local signs of infection and by values of temperature and leucocyte counts within or close to normal values. In this period measurements of the sedimentation reaction and C-reactive protein were elevated, and were markers of persistent infection. At the Department of Clinical Microbiology in the county of Copenhagen blood cultures from a total of 49 patients were found to be positive for S. aureus during the period January to March 1996. Six patients were found to have osteomyelitis (12%, including four cases of spondylitis) and nine patients were suspected of having osteomyelitis. This frequency of patients with S. aureus bacteraemia having osteomyelitis was significantly higher than reported in another Danish study (10), which together with the severe outcome of the infection emphasizes the need for attentiveness to these serious complications of S. aureus bacteraemia.

Staphylococcus aureus carriage and infections among patients in four haemo- and peritoneal-dialysis centres in Denmark. The Danish Study Group of Peritonitis in Dialysis (DASPID).

A three-month prospective surveillance study was undertaken in four dialysis centres to establish the prevalence of Staphylococcus aureus carriage in a Danish population of patients on haemodialysis (HD) or on continuous ambulatory peritoneal dialysis (CAPD). General data such as sex, age, diagnosis, number of months in dialysis, hospital and ward were registered on a precoded form. Standardized nose and four skin swabs (axillae, groins, perineum) were performed on the first day of the survey. After one and two months, nose swabs were collected. Infections were registered and cultures were sent for phage-typing together with the S. aureus strains isolated from the swabs; 59.5% of HD patients and 51.2% of CAPD patients carried S. aureus. Permanent carriage was most frequent (P < 0.00009), primarily in the nose (44.0 and 34.9%, respectively in HD and CAPD). Skin carriage alone was rare (2.4 and 4.7%). Approximately one third (36.6 and 40.7%) of infections were caused by S. aureus. Although diabetics were not significantly more frequent carriers (60.5%) than non-diabetics (55.0%), the incidence of infection was much higher (26.3% vs. 10.3%, P = 0.004). In CAPD, peritonitis and tunnel/exit-site infections predominated (81.4%), often caused by S. aureus (34.8%). More than two thirds of the infections in HD patients were related to intravascular catheterization. The most serious infection was septicaemia, in all cases due to S. aureus. S aureus infections occurred significantly more frequently among carriers (P = 0.005), and more than half the patients were infected by the same or possibly the same strain as they carried in the nose or on skin. Different regimens for the elimination of S. aureus carriage in dialysis patients are discussed. A policy for risk assessment of patients should be developed, and the elimination of S. aureus carriage before dialysis should be encouraged. Controlled trials comparing the cost-effectiveness of recommended regimens to eliminate carriage in HD/CAPD patients are needed. Nose swabs are reliable indicators of carriage in dialysis patients.

Cefuroxime resistance in Escherichia coli. Resistance mechanisms and prevalence.

In order to characterize cefuroxime resistance in Escherichia coli 22 clinical isolates were investigated for susceptibility to different beta-lactam antibiotics and ciprofloxacin. The production of beta-lactamases, the pattern of the major outer membrane proteins (OMPs), and the plasmid profiles were determined for these isolates. Ten of the isolates were resistant to ceftazidime, two to cefotaxime, and none was resistant to imipenem or ciprofloxacin. The dominating resistance mechanism was hyperproduction of the chromosomally encoded beta-lactamase to some extent accompanied by alterations of the OMP's. Two isolates with low ampicillin MIOs seemed solely to have alteration of the OMPs. None of the isolates produced plasmid-mediated extended-spectrum beta-lactamases. In addition, the prevalence of cefuroxime resistance was investigated. The prevalence as attained in 8704 clinical isolates of E. coli collected from Copenhagen County during a 5-year period (1990-1994) was 4.4%, but there was considerable variation among specimens from different sites of the body. Isolates from blood were much less resistant (2.5%) than isolates from the respiratory tract (9.7%).

Coagulase-negative Staphylococci in Danish blood cultures: species distribution and antibiotic susceptibility.

The distribution and antibiotic susceptibility of coagulase-negative staphylococci (CoNS) isolated from blood cultures was examined in samples from hospitals covering most of Denmark. A total of 499 CoNS isolates were detected in 477 blood cultures from 340 patients and speciated as Staphylococcus epidermidis, 285; Staphylococcus hominis, 61; Staphylococcus haemolyticus, 43; Staphylococcus warneri, 12; Staphylococcus cohnii, 7; Staphylococcus saprophyticus, 4; Staphylococcus capitis, 2 and Staphylococcus lugdunensis, 1. Seventy-eight isolates could not be identified to species level and six were Micrococcus spp. In 108 (22.6%) blood culture sets, more than one CoNS strain were found, as detected by species identification, antibiogram and biotyping. Significantly more blood cultures from patients in university hospitals were drawn from central venous catheters. Comparing university and non-university hospitals, the overall antibiotic susceptibility among CoNS was only slightly different, except for methicillin and amikacin. The prevalence of methicillin-resistant strains was 35.1% in the university hospital strains vs. 25.3% in the non-university hospital strains. The overall prevalence of methicillin resistance was 32%. Great geographic variation in both species distribution and antibiotic resistance was observed. The high prevalence of S. epidermidis makes subtyping of this species important.

A 6-month prospective study of hospital-acquired bacteremia in Copenhagen county.

During a 6-month period, 892 positive blood cultures were detected in the Copenhagen County hospitals. 302 (34%) were regarded as contaminations, and of the remaining cases 419 (71%) were community-acquired and 171 (29%) hospital-acquired, giving incidence rates of 6.8/1,000 admissions and 2.8/1,000 admissions, respectively. Both frequency and rate of hospital-acquired bacteremia were lower compared to most other studies. E. coli was more commonly found in community-acquired infections, while coagulase-negative staphylococci were the organisms most often considered as a contaminant. The main causative organisms in hospital-acquired infections were S. aureus (n = 37) and E. coli (n = 34). The proportion of polymicrobial bacteremias in this study was lower compared to most other studies (8%). E. coli from hospital-acquired infections were resistant to ampicillin in 42% of cases, but other Enterobacteriaceae showed higher percentage of resistance to beta-lactam antibiotics. S. aureus was penicillin-resistant in 92% of cases, but no methicillin-resistant strains were isolated. The frequency of antibiotic resistance was low compared to reports from other countries. A total of 136 hospital-acquired cases were followed prospectively. 61% of the patients were male and 46% were > or = 60 years of age. Most patients had predisposing diseases, 90% had foreign body and/or recent surgery performed, and 74 (54%) had an intraveneous catheter. The portal of entry was known in 132 (97%) of the cases, the most common being the urinary tract (42%), followed by an intravenous catheter (30%). The prevalence of urinary tract catheters gave an increased number of cases with E. coli bacteremia. The mortality was 16%.

[Salmonella dublin]. / Salmonella dublin.

Salmonella dublin's natural host is cattle; it may cause acute disease in calves, while adult animals may be asymptomatic carriers. In humans S. dublin is the most invasive of the zoonotic Salmonella-bacteria found in Denmark. It is much more frequently isolated from the blood than from the faeces and may give rise to serous metastatic infections in practically all organs. The number of registered human infections rose from zero to 46 per year during the period 1980-1988, but has now stabilized at a level of about 20 per year. Outbreaks have been described abroad as being caused by unpasteurised milk and cheese; in Denmark beef and cow's liver must be viewed as the dominant source of infection. The direct routes of infection are, however, unknown. Tightening of regulations for the slaughtering of animals from S. dublin infected herds, optimal hygiene in the slaughterhouses and increased cooperation between the veterinary and medical professions concerning investigation of routes of infection are necessary measures to be taken in order to reduce the number of human S. dublin infections.

Detection of Chlamydia trachomatis in individual and pooled endocervical and urethral scrapes by a commercially available polymerase chain reaction.

The aim of this study was to compare a commercially available PCR kit (Amplicor, Roche) with our present routine analysis (SYVA EIA) for the detection of genital C. trachomatis infection in females. Furthermore, we wished to investigate the possibility of pooling samples for PCR analysis. Two hundred and sixty-eight consecutive female patients attending two gynecology clinics in Copenhagen, Denmark were included in this study. Compared to the number of samples regarded as true positives, PCR had a sensitivity of 100% (18/18) and EIA a sensitivity of 83.3% (15/18). The specificity of the PCR analysis was 99.2% (248/250) compared to 100% (250/250) for the EIA. By pooling patient samples (five patient samples in each pooled sample), a 39% reduction in reagent costs was obtained without affecting the sensitivity. In conclusion, the implementation of a standardized commercially available C. trachomatis PCR kit leads to a marked increase in analytical sensitivity compared to EIA without affecting the specificity. When pooled samples were analyzed, the cost per patient sample was reduced, but further large-scale studies are needed to rule out the possibility of a reduced sensitivity due to the dilution of individual patient samples.

[Prevention of duodenal ulcer recurrence with penicillin]. / Forebyggelse af recidiv af ulcus duodeni med penicillin.

The aim of this study was to test the hypothesis that infection with Helicobacter pylori is essential for recurrence of duodenal ulcer. We performed a randomized controlled trial of the relapse rate of duodenal ulcer during 12 weeks treatment with penicillin V or placebo in 170 out-patients from five centres. The relapse rate was 9% during treatment with penicillin and 50% with placebo, P < 0.0001. It is concluded that infection with penicillin-sensitive bacteria, i.e. H. pylori, plays an important role for recurrence of duodenal ulcer disease. Penicillin V suppresses this infection but does not eradicate it.

Prevention of duodenal ulcer recurrence with penicillin. A double-blind, placebo-controlled trial.

Eradication of Helicobacter pylori is associated with a reduced recurrence of duodenal ulcer (DU). The relationship between H. pylori and DU has been interpreted as causal, but the evidence has been criticized for methodologic reasons. To ascertain whether an antibiotic with no effect on epithelial-cell integrity prevents DU recurrence, we conducted a randomized double-blind trial of phenoxymethylpenicillin (PEN), 2.4 twice daily, and placebo (PLA). Patients with an active DU and positive H. pylori culture from antral biopsy specimens were treated with 40 mg omeprazole daily for 4 weeks, but at week 2 they were allocated at random to PEN (85 patients) or PLA (85 patients) for up to 14 weeks. Those without recurrence during this treatment were followed up for another 6 months. Endoscopy and H. pylori culture were performed at the end of the treatment period and at the end of follow-up, and in between if ulcer symptoms recurred. During the treatment period the ulcer relapse rate was 5 of 58 (9%) in the PEN group and 34 of 68 (50%) in the PLA group (P < 0.0001, log-rank test), with 53% and 14%, respectively, of the patients in the two groups being H. pylori-negative. The relapse rate in the PEN group did not differ between H. pylori-negative and H. pylori-positive patients. The recurrence rate in the PEN group remained low for another 5 months but then approached the rate in the PLA group. The prevalence of H. pylori-negative patients at the end of follow-up was 20% in the PEN group and 10% in the PLA group. These data provide strong evidence that DU has a bacterial cause, with H. pylori as the likely agent.