Comparison of PCR detection of mecA with agar dilution and Etest for oxacillin susceptibility testing in clinical isolates of coagulase-negative staphylococci.

Oxacillin-resistant staphylococci are heterogeneous in their expression of resistance to beta-lactam antibiotics. Different recommendations regarding screening methods for routine use have been published. In this study, the susceptibility to oxacillin of 232 coagulase-negative staphylococci (CoNS) was determined by agar dilution, Etest and presence of the mecA gene. When an oxacillin resistance breakpoint of > or = 0.5 mg/L was used, the sensitivity and specificity for agar dilution were 97.6% and 100%, and those for Etest were 100% and 95.4%. The current National Committee for Clinical Laboratory Standards oxacillin breakpoint recommendation will categorise accurately the CoNS species encountered commonly.

Outbreak of infection with high-level gentamicin-resistant Enterococcus faecalis (HLGRE) in a Norwegian hospital.

OBJECTIVES: To examine and characterize a suspected outbreak of high-level gentamicin-resistant Enterococcus (HLGRE) infection. METHODS: Eighty-nine patients with clinical infection diagnosed during hospital stay or within 30 days after discharge in the period from June 1995 to 31 December 1999 were included in the study. One control patient was assigned for each HLGRE patient according to localization in the hospital (same ward), time of admission (+/-3 months), and age (+/-10 years). Unadjusted risk analysis and multivariate logistic regression analysis were performed. Sixty-nine HLGRE strains were subjected to PCR amplification of the genes coding for aminoglycoside-3'-O-phosphoryltransferase-III (APH(3')-III) and aminoglycoside-6'-N-acetyltransferase/2"-O-phosphoryltransferase-III (AAC(6')/APH(2")). RESULTS: The gene aacA/aphD, associated with HLGRE, was detected by PCR in all isolates, and the gene aphA3, associated with high-level streptomycin, kanamycin and amikacin resistance, was detected in 56 of the 69 isolates. None of the 69 isolates was resistant to glycopeptides or ampicillin. Resistance to ciprofloxacin was found in 57 (82.6%). Pulsed-field gel electrophoresis analysis revealed 12 different genotypes, among which two major clusters dominated. CONCLUSIONS: Both clonal expansion and the emergence of unique strains contributed to the increased number of infections caused by HLGRE. Urinary catheterization, duration of hospital stay and antibiotic therapy were significant risk factors for HLGRE infection.

Prevalence of resistance to ampicillin, gentamicin and vancomycin in Enterococcus faecalis and Enterococcus faecium isolates from clinical specimens and use of antimicrobials in five Nordic hospitals.

We determined the species distribution and prevalence of ampicillin resistance, high-level gentamicin resistance (HLGR) and vancomycin resistance among clinical enterococcal isolates from five Nordic laboratories (Bergen, Tromsø, Uppsala, Aarhus and Reykjavik). Isolates represented three different groups: (i) all blood culture isolates from 1999; (ii) consecutive in-patient isolates (maximum 40); and (iii) consecutive outpatient isolates (maximum 40) collected during March to May 2000. Antimicrobial use data were collected at the national and hospital level. A high proportion (31.4%) of Enterococcus faecium was detected among blood culture isolates, in contrast to only 4.2% among isolates from outpatients. Ampicillin resistance was not found in Enterococcus faecalis, in contrast to 48.8% in E. faecium isolates. HLGR rates varied considerably between laboratories (1.1-27.6%). Acquired vancomycin resistance was not detected. There were no significant differences in the prevalences of HLGR between in-patient and outpatient isolates at individual hospitals. A cluster of clonally related ampicillin-resistant and HLGR E. faecium isolates was demonstrated in one of the hospitals. The lowest level of hospital antimicrobial use, the lowest proportion of E. faecium and the lowest prevalence of resistance were observed in Reykjavik. The study showed a relatively low level of resistance in enterococci, as compared with most European countries and the USA. However, there were large differences between hospitals with regard to the relative proportion of E. faecium isolates, their susceptibility to ampicillin and gentamicin, as well as the prevalence of HLGR in E. faecalis isolates. This indicates a potential for further improvement of antibiotic policies, and possibly hospital infection control, to maintain the low resistance levels observed in these countries.

The prevalence of faecal carriage of ampicillin-resistant and high-level gentamicin-resistant enterococci among inpatients at 10 major Norwegian hospitals.

From March to October 1999, 854 patients hospitalized at 10 major Norwegian hospitals were screened for rectal carriage of ampicillin-resistant enterococci (ARE) and high-level gentamicin-resistant enterococci (HLGRE). A total of 59 ARE carriers (prevalence 6.9%, range 0-22% among hospitals) and 28 HLGRE carriers (prevalence 3.3%, range 1-11%) were detected. All ARE or HLGRE strains were susceptible to vancomycin, whereas 77% of the ARE isolates were resistant to ciprofloxacin. All the ARE strains were identified as Enterococcus faecium, and 48% of these were genomically closely related as shown by PFGE. Specific point mutations in the pbp5 gene were associated with reduced susceptibility to ampicillin. The adjusted risk of becoming a carrier of ARE was related to the use of glycopeptides [odds ratio (OR) = 4.8], the use of any antimicrobial agent (OR = 3.1) and more than one hospital admission during the last six months (OR = 2.0). Twenty-five of 28 HLGRE isolates were Enterococcus faecalis. The aacA/aphD genes were detected in 26 (93%) and the aphA3 in 19 (68%) of the HLGRE isolates. Sixty-four percent of the HLGRE isolates belonged to two PFGE clusters. Consumption of antimicrobial agents was also a significant risk factor for HLGRE colonization (OR = 5.4), while prescription of penicillins was associated with reduced risk (OR = 0.28).

Typing of Pseudomonas aeruginosa strains in Norwegian cystic fibrosis patients.

OBJECTIVES: Typing of Pseudomonas aeruginosa isolates from Norwegian cystic fibrosis (CF) patients with chronic Pseudomonas lung infection in order to see whether cross-infection might have occurred. METHODS: Isolates from 60 patients were collected during the years 1994-98, and typed by pulsed field gel electrophoresis. RESULTS: Seventy-one strains were identified. One large cluster of identical strains included 27 patients, and 13 smaller clusters of 2-4 patients were found (26 patients). Seven patients had a strain not shared by other patients (private strains). Harboring the main cluster strain was significantly associated with participation in summer camps and training courses (P = 0.004, chi-squared test). There were no associations with regular admissions to hospital (intravenous antibiotic courses) or smaller social gatherings of short duration. Small clusters and private strains were not associated with any of the risk factors. All strains were sensitive to colistin. The minimal inhibitory concentrations were generally lower in Norwegian P. aeruginosa strains compared with isolates from Danish patients. CONCLUSIONS: Our results indicate that cross-infection with P. aeruginosa between cystic fibrosis patients has occurred.

Comparative evaluation of a commercial test for rapid identification of methicillin-resistant Staphylococcus aureus.

The performance and ease of use of the recently introduced MRSA screen test (Denka Seiken Co. Ltd., Japan) for the identification of methicillin-resistant Staphylococcus aureus was evaluated in comparison with the BBL Crystal MRSA ID System (Becton Dickinson Europe, France). A total of 109 strains of S. aureus, consisting of 57 strains of MecA-negative S. aureus and 52 strains of MecA-positive S. aureus, were tested. With MecA PCR as the gold standard, the MRSA screen test had 98% sensitivity and 98% specificity, whereas the BBL Crystal MRSA ID System had 98% sensitivity and 95% specificity. The simplicity of use and rapid result make the MRSA screen test a valuable tool in the clinical microbiology laboratory pending demonstration of the MecA gene that should still always be done.

Antibiotic susceptibility of blood culture isolates of Enterobacteriaceae. A Norwegian multicenter study.

From May to November 1997 each of six major hospitals throughout Norway collected 72 to 104 consecutive blood culture isolates of Enterobacteriaceae, altogether 563 isolates. Escherichia coli was the predominating organism (69%), followed by Klebsiella spp. (15%), Enterobacter spp. (6%), and Proteus mirabilis (4%). The susceptibility of the isolates to ampicillin, cefuroxime, ceftazidime, imipenem, tobramycin, and ciprofloxacin was determined by the E-test. 37% and 7% of the isolates were resistant to ampicillin and cefuroxime, respectively, and 1% were resistant to ceftazidime and tobramycin. Only one isolate of P. mirabilis was imipenem resistant. All isolates were susceptible to ciprofloxacin. The prevalence of ampicillin-resistant isolates at each hospital varied from 21 to 45%, and of cefuroxime-resistant isolates from 3 to 9%. The results were compared with those of a similar study performed in 1991-1992. No significant changes in the susceptibility to the various agents could be demonstrated. The high frequency of isolates resistant to ampicillin has clearly limited the usefulness of this agent in the treatment of septicemia and other serious infections caused by Enterobacteriaceae.

Eradication of non-typhoid salmonellae in acute enteritis after therapy with ofloxacin for 5 or 10 days.

Eradication of non-typhoid salmonellae was evaluated in a randomized, double-blinded study of 49 patients with acute enteritis after therapy with ofloxacin 400 mg once daily for 5 or 10 days. Early eradication of salmonellae was found in 57% of patients in the 5 day therapy group and in 74% of patients in the 10 day therapy group. This difference was larger among severely ill patients. Together with our previous study of ofloxacin therapy for 3 days or placebo, this shows that early eradication of non-typhoid salmonellae increases with duration of ofloxacin therapy without an increase in persistence of salmonellae in stools or development of resistant strains.

[Outbreak of multiresistant Acinetobacter baumannii infection]. / Utbrudd av infeksjon med multiresistent acinetobacter baumannii.

BACKGROUND: Nosocomial infections caused by multiresistant gram-negative bacteria represent an increasing problem, especially among intensive care patients. A serious outbreak of infection caused by multi-resistant Acinetobacter baumannii occurred in four burn patients. Acinetobacter is a gram-negative coccibacilli which is widespread in nature, and has been reported as an increasing problem in critically ill patients. MATERIALS AND METHODS: The outbreak strain was introduced from Alicante, Spain, by a transferred patient. This strain was resistant to all commonly available systemic antibiotics (including the karbapenems and all aminoglycosides), and sensitive only to polymyxin B. Two patients were critically ill, one of them died in septic shock. RESULTS: The ward was closed for admission of new patients and hygiene precautions were strengthened. Extensive testing of staff and equipment revealed multi-resistant A baumannii on a shower trolley shared by several patients. The outbreak strain was also identified by restriction endonuclease analysis. The patients were kept strictly isolated until their burn wounds were sufficiently healed to allow them to be discharged to their homes. INTERPRETATION: Following discharge of the last patient and extensive cleaning and disinfection of the entire ward, the particularly resistant strain has not reoccurred. Still, this experience may warrant screening for multiresistant gram-negative rods in patients transferred from regions where broad resistance to antibiotics is a common problem.

Vancomycin resistance emerging in a clonal outbreak caused by ampicillin-resistant Enterococcus faecium.

OBJECTIVES: To describe the first nosocomial outbreak of ampicillin-resistant Enterococcus faecium (ARE) in Norway, where a few vancomycin-resistant strains have also been identified. METHODS: All cases of ARE and vancomycin-resistant Enterococcus faecium (VRE) diagnosed by the medical microbiological laboratories in a region inhabited by approximately 1 million people were registered. Isolates obtained during the period 1 January 1995 to 31 December 1996 were characterized by pulsed field-gel electrophoresis and the clinical data were recorded. RESULTS: One hundred and forty-nine patients (64 males, 85 females, mean age 70.5 years) were infected with ARE. Isolates from 115 cases were genomically related to the outbreak strain. Infections included bacteremia (14), wound infections (31), urinary tract infections (97) and other infections (seven). Most had a severe underlying disease and 93% of the patients had received antibiotics for a mean time of 23 days. Twenty-four patients (16.1%) died during hospitalization. Four infections were caused by a vanB-type VRE that was genomically related to the ARE outbreak strain. The prescription rate for vancomycin was low, but an increase in vancomycin use paralleled the appearance of VRE. The highest monthly incidence rate was 2.5 per 1000 patient admissions in July 1996 declining to 0.5 in December 1996. CONCLUSIONS: The first nosocomial outbreak caused by ARE was observed in 1995 in Norway and is still ongoing. One year after the onset, VRE occurred in wards which had a relatively high consumption of vancomycin.

Equal symptomatic outcome after antibacterial treatment of acute lower urinary tract infection and the acute urethral syndrome in adult women.

OBJECTIVE: To compare symptomatic outcome after antibacterial treatment in patients with acute lower urinary tract infection and the acute urethral syndrome. DESIGN: A multipractice study; patients registering symptoms prospectively for 3 days by means of a diary. SETTING: General practices in western Norway. SUBJECTS: 153 adult women with acute lower urinary tract symptoms. MAIN OUTCOME MEASURE: Patient's prospective registration of symptom distribution and duration after starting antibacterial treatment. RESULTS: Fifty-one patients with acute lower urinary tract infection and 58 patients with the acute urethral syndrome were included. There were no differences in age, history of urinary tract infection, actual symptoms, or symptom duration between the groups. Symptom duration was nearly identical in the two groups among those who became asymptomatic during the 3 days of registration, ranging from 1.2 days for urgency to 1.6 days for dysuria. Almost half of the patients in each group still had some symptom left after 3 days. CONCLUSIONS: Symptomatic outcome was equal after antibacterial treatment whether the patient was classified as having acute cystitis or the acute urethral syndrome. Consequently, the general practitioner may rely on symptoms alone when starting antibacterial treatment in adult women with suspected cystitis.

[Once-daily dosage of aminoglycosides--a therapeutic simplification and an economical benefit]. / Dosering av aminoglykosider en gang i døgnet--en terapeutisk forenkling og et økonomisk fremskritt.

Conventionally, aminoglycosides have been administered in two or three daily doses. Numerous in-vitro and animal experiments and several clinical trials favour a once-daily dosage regimen of aminoglycosides, which provides a more rapid concentration-dependent bacterial killing and is probably less toxic than two or three dosage regimens. In this article the pharmacological and microbiological background for once-daily aminoglycoside administration is reviewed, and some controlled trials are discussed. Recommendations for clinical practice are given.

Are resistance patterns in uropathogens published by microbiological laboratories valid for general practice?

During 7 months from August 1994, 171 urine samples were collected consecutively in general practice in Western Norway from female patients with suspected lower urinary tract infection. For each of the 171 samples, 2 samples from adult females received from general practice at the microbiological laboratory on the same day were selected using a predetermined system. Samples noted as treatment controls and samples from pregnant patients were discarded. Bacteriuria was found in 101/171 (59.1%) vs 220/342 (64.3%) of the samples. The general practice material contained more bacteriuric samples with Escherichia coli (83.2% vs 71.8%, p<0.05) and Staphylococcus saprophyticus (11.9 vs 6.4%), and fewer with other Gram-negative rods (4.0% vs 15.9%, p<0.01) and enterococci (1.0% vs 5.9%, p<0.01). The frequency of resistant isolates was substantially lower in the samples from general practice for all antibacterial agents tested: amoxycillin 18.9% vs 23.9%, mecillinam 1.1% vs 4.7%, trimethoprim 12.9% vs 18.5%, cotrimoxazole 12.0% vs 15.4%, sulphonamide 20.0% vs 28.4%, nitrofurantoin 3.0% vs 9.7% (p<0.05). Data from local laboratories exaggerate the resistance problems among uropathogens found in urine samples in general practice.

Outbreak of meningococcal disease in western Norway due to a new serogroup C variant of the ET-5 clone: effect of vaccination and selective carriage eradication.

A new sulphonamide resistant (SR) C: 15:P1.7,16 meningococcal strain, a variant of the ET-5 clone, dominated in an outbreak of 22 cases in western Norway commencing in 1995. The first eight patients were 15-21 years old from the Nordhordland area, initiating a carrier study in the local high schools. Carriage of SR serogroup C meningococci was detected by routine methods and treated with a single dose of ofloxacin 400 mg. Of 20 treated carriers, 14 harboured the outbreak strain C: 15:P1.7,16. Vaccination of 4000 children, adolescents and close contacts of patients was also performed. After the intervention, 14 additional cases of meningococcal disease occurred, 8 due to the outbreak strain. However, incidence rates dropped from 180 to 30 per 100000 per year in the student population, but increased from 0 to 13 in the rest of the population in Nordhordland. Carriage eradication is not generally recommended in Norway. However, tracing and treating meningococcal carriage may have reduced transmission and disease in this outbreak situation.

[Infections caused by multiresistant enterococci in Norway]. / Infeksjoner forårsaket av multiresistente enterokokker i Norge.

During the last decade antimicrobial resistant pathogens have become a major medical problem. Internationally, multiresistant enterococci have increased nosocomial morbidity and mortality. Such strains are often resistant to ampicillin, aminoglycosides, and glycopeptides such as vancomycin. The spread of these strains has been shown to correlate to the use of antibiotics and the practice of suboptimal infection control within health care facilities. The current situation in Norwegian hospitals is presented, including the only six cases with infections and the three carriers of vancomycin resistant enterococci found to date. Surveillance in the hospitals shows that such strains are uncommon in non-infected patients. To maintain this favourable situation it is necessary to continue to practice effective methods of infection control and to employ sound antibiotic policies.

Constant low rate of fungemia in norway, 1991 to 1996. The Norwegian Yeast Study Group.

Since 1991 information on yeast isolates from blood cultures has been recorded prospectively from all microbiological laboratories (5 university and 16 county or local hospital laboratories) in Norway (population, 4.3 million). From 1991 to 1996 a total of 571 episodes of fungemia in 552 patients occurred (1991, 109 episodes; 1992, 81 episodes; 1993, 93 episodes; 1994, 89 episodes; 1995, 98 episodes; and 1996, 101 episodes). The fungemia rates per 10,000 patient days were 0.29 in 1991 and 0.27 in 1996. The average rates for the years 1991 to 1996 were 0.37 for the university laboratories and 0.20 for the other laboratories. These rates are low compared to the rate (0. 76) in five Dutch university hospitals in 1995 and the rate (2.0) in Iowa in 1991. The four most frequently isolated species were Candida albicans (66%), Candida glabrata (12.5%), Candida parapsilosis (7.6%), and Candida tropicalis (6.4%). The incidences of both C. albicans (range, 63 to 73%) and C. glabrata (range, 8.4 to 15.7%) varied somewhat throughout this period, but no significant increase or decrease was noted. MICs of amphotericin B, flucytosine, and fluconazole were determined for 89% of the isolates. All were susceptible to amphotericin B, and only 29 (5.6%) strains had decreased susceptibility to flucytosine. All C. albicans isolates were susceptible to fluconazole. The percentage of yeast isolates with decreased susceptibility to fluconazole (MICs, >/=16 microgram/ml) did increase, from 9.6% in 1991 and 1992 to 12.2% in 1994, 16.1% in 1995, and 18.6% in 1996. This was largely due to increases in the percentages of resistant C. glabrata and Candida krusei strains in the last 2 years. Compared to the incidence in other countries, it is remarkable that Norway has such a low and constant incidence of fungemia. A possible reason for this difference might be a restricted antibiotic use policy in Norway.

Low faecal carrier rate of vancomycin resistant enterococci in Norwegian hospital patients.

The faecal carrier rate of vancomycin resistant enterococci (VRE) was surveyed among 616 patients in selected departments of 7 Norwegian hospitals. One Enterococcus gallinarum isolate harbouring a vanB2 element was recovered from a child with malignant disease treated with vancomycin and ceftazidime. No vancomycin resistant Enterococcus faecalis or Enterococcus faecium were detected and no VRE isolates of the VanA type were identified. The low level of VRE carriage corresponds to the limited use of glycopeptide antibiotics for human therapeutic purposes in Norway. It indicates a low risk of acquiring VRE infections in Norwegian hospitals.

Antibiotic susceptibility of blood culture isolates of Enterobacteriaceae from six Norwegian hospitals 1991-1992.

From August 1991 to February 1992, each of the six largest hospitals throughout Norway collected 84 to 107 consecutive blood culture isolates of Enterobacteriaceae, altogether 571 isolates. The distribution of various species and genera at the different hospitals was uniform; Escherichia coli being most prevalent (57-67%), followed by Klebsiella spp. (12-18%) and Proteus mirabilis (7-11%). Twenty-one and 4% of E. coli isolates were resistant to ampicillin and cefuroxime, respectively, and 11% of Klebsiella isolates were cefuroxime resistant. Five Enterobacter isolates and one Citrobacter isolate were resistant to ceftazidime, and one Salmonella isolate was resistant to imipenem. All isolates were susceptible to ciprofloxacin and tobramycin. These results were compared with the antibiotic consumption in each hospital region. Although hospitals in the regions with the highest consumption of ampicillin tended to have a higher percentage of isolates resistant to this agent, no significant differences were found. There was no significant difference between hospitals regarding prevalence of cefuroxime-resistant isolates.

Candida norvegensis: a fluconazole-resistant species.

Candida norvegensis has been an unusual cause of infections in humans. In Norway this species was isolated from eight patients from 1990 to 1996 and was of probable pathogenic significance in four of them. All isolates were resistant to fluconazole. The same was true for two C. norvegensis isolates from before 1940, and it is therefore assumed that the fluconazole resistance is inherent.

Physical predictors of infection in patients treated with clean intermittent catheterization: a prospective 7-year study.

OBJECTIVE: To study urinary tract complications in patients treated using long-term clean intermittent catheterization (CIC), and to evaluate the physical factors which might be implicated in these complications. PATIENTS AND METHODS: During 1995, 170 patients (84 men and 86 women, mean age 56.9 years) with a mean duration of use of CIC for 8.8 years were assessed for complications related to CIC. The same patients had participated in a thorough follow-up study during 1988-9 and were examined again using questionnaires and the analysis of urine samples. CIC was practised by two-thirds of the patients because they had neurogenic bladder dysfunction and for non-neurogenic dysfunction in the remainder. RESULTS: In this prevalence study, 111 patients (65%) had no signs of clinical urinary tract infection (UTI), while 10 patients (6%) had pronounced symptoms. The remaining 29% had only minor signs of UTI. There were three predictive factors of clinical UTI: women reported more infections than men, the patients most affected by UTI in the present study were those suffering UTI during the 1988-9 study and patients with UTI had the highest mean catheterization volume now, and the highest increase in mean catheterization volume from 1989 to 1995. Bacteriuria was found in 61% of the urine samples, with Escherichia coli the dominant species among women and Gram-positive cocci among men. Patients who did not use anti-infective agents had a 31% rate of sterile urine while the corresponding value among those using antibiotics was 54%. The frequency of catheterization was the only variable predictive of bacteriuria apart from the use of antibiotics. CONCLUSION: This study confirms previous reports showing CIC to be an excellent procedure for minimizing urinary tract complications and supports the current recommendations, e.g., restricting the use of antibiotics in patients using CIC and ensuring that they catheterize sufficiently often to ensure that the mean volume of each catheterization is kept to < 400 mL in adults.