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.

Evidence for intraaxonal spread of Listeria monocytogenes from the periphery to the central nervous system.

Rhombencephalitis due to Listeria monocytogenes is characterized by progressive cranial nerve palsies and subacute inflammation in the brain stem. In this paper, we report observations made on mice infected with L. monocytogenes. Unilateral inoculation of bacteria into facial muscle, or peripheral parts of a cranial nerve, induced clinical and histological signs of mainly ipsilateral rhombencephalitis. Similarly, unilateral inoculation of bacteria into lower leg muscle or peripheral parts of sciatic nerve was followed by lumbar myelitis. In these animals, intraaxonal bacteria were seen in the sciatic nerve and its corresponding nerve roots ipsilateral to the bacterial application site. Development of myelitis was prevented by transsection of the sciatic nerve proximally to the hindleg inoculation site. Altogether, our results support the hypothesis that Listeria rhombencephalitis is caused by intraaxonal bacterial spread from peripheral sites to the central nervous system.

Antibiotic sensitivity still prevails in Norwegian blood culture isolates.

We describe the antimicrobial susceptibility of bacteraemia isolates from Norway. From March 1998 to February 1999, four university hospitals covering all parts of Norway collected their first 10 isolates each month. Minimal inhibitory concentrations were determined for: Enterobacteriaceae (n=192), staphylococci (n=89) and Streptococcus pneumoniae (n=69) using the Etest. NCCLS breakpoints were used. About 20% of all blood culture isolates in Norway in this period were investigated. Compared with countries outside Scandinavia antibiotic sensitivity still prevails. Only minor differences in resistance were found between participating hospitals, between hospital departments and between hospital- and community-acquired pathogens. The prudent use of antibiotics in Norway may contribute to the fact that antibiotic resistance still remains low in the most common bacterial pathogens causing bloodstream infections.

Bacteriological findings in nasopharynx specimens from patients with a clinical diagnosis of acute sinusitis.

OBJECTIVE: To study results from bacteriological specimens from nasopharynx in patients with a clinical diagnosis of acute sinusitis in relation to CT findings. DESIGN: Prospective study. SETTING: Patients from general practice in Vestfold county, Norway. PATIENTS: 427 patients 15 years and older from two studies with a clinical diagnosis of acute sinusitis, and who were examined with coronal CT scans of the paranasal sinuses. Fluid level or total opacification of any sinus was taken as a hallmark of sinusitis. MAIN OUTCOME MEASURES: Bacteriological findings in nasopharynx specimens and proportions of various sinus pathogens in patients with and without sinusitis confirmed by CT. RESULTS: In the study, 252 patients had acute sinusitis and 175 patients did not. In the sinusitis groups, 27% of the patients had Streptococcus pneumonia, 12% had Staphylococcus aureus and 10% had Haemophilus influenzae in their nasopharynx specimens. Forty-five percent of the patients had normal nasal flora or no growth. The strains of Streptococcus pneumonia and Haemophilus influenzae showed high sensitivity to PcV, while the Moraxella strains were resistant to it. CONCLUSION: Streptococcus pneumoniae and Haemophilus influenzae were the most frequent sinus pathogens found in the nasopharynx specimens, and they were significantly more frequent in the group with confirmed sinusitis. The proportion of specimens with normal nasal flora or no growth was significantly higher in the non-sinusitis group.

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.

Comparative fingerprinting analysis of Campylobacter jejuni subsp. jejuni strains by amplified-fragment length polymorphism genotyping.

Amplified-fragment length polymorphism (AFLP) analysis with the endonucleases BglII and MfeI was used to genotype 91 Campylobacter jejuni subsp. jejuni strains from outbreaks and sporadic cases. AFLP-generated fragments were labeled with fluorescent dye and separated by capillary electrophoresis. The software packages GeneScan and GelCompar II were used to calculate AFLP pattern similarities and to investigate phylogenetic relationships among the genotyped strains. The AFLP method was compared with two additional DNA-based typing methods, pulsed-field gel electrophoresis (PFGE) using SmaI and restriction fragment length polymorphism analysis on PCR products (PCR-RFLP) of the flaA and flaB genes. We found that AFLP analysis of C. jejuni strains is a rapid method that offers better discriminatory power than do both PFGE and PCR-RFLP. AFLP and, to a lesser extent, PCR-RFLP could differentiate strains within the same PFGE profiles, which also makes PCR-RFLP an alternative to PFGE. We were able to clearly distinguish 9 of 10 recognized outbreaks by AFLP and to identify similarities among outbreak and sporadic strains. Therefore, AFLP is suitable for epidemiological surveillance of C. jejuni and will be an excellent tool for source identification in outbreak situations.

Outbreak of Campylobacter infection in a subartic community.

A presumably waterborne outbreak of Campylobacter jejuni/coli infection in a subarctic community is described. Drinking water supplied to residents was delivered unchlorinated during a 4-week period. No Campylobacter sp. was recovered from the water supply. Three hundred thirty individuals (15% of the 2,200 exposed) became ill. Diarrhoea, abdominal pain, fever, nausea and joint pain occurred in 81%, 30%, 29%, 43% and 21%, respectively. Nine percent reported swelling of joints, and two cases of reactive arthritis occurred. A Campylobacter sp. was isolated from 9 of 33 individuals who became ill and from 1 of 33 healthy controls. All culture-positive individuals, 46% of culture-negative ill persons and 27% of healthy controls were seropositive. All strains recovered had an identical DNA profile.

Helicobacter pylori infection and risk of cardia cancer and non-cardia gastric cancer. A nested case-control study.

BACKGROUND: Helicobacter pylori infection is an established risk factor for gastric adenocarcinoma. Potential confounding by socioeconomic factors has not been adequately assessed, and the magnitude of the relative risk in relation to gastric subsites, morphologic subtypes, sex, age, and follow-up time need further study. METHODS: We conducted a serologic case-control study nested within the Norwegian JANUS cohort. Between 1972 and 1986 serum was collected from 101,601 subjects who were followed up with regard to cancer development through 1992. RESULTS: Among 208 gastric adenocarcinoma cases, we found a strong positive association between H. pylori infection and non-cardia gastric cancer (odds ratio (OR), 5.15; 95% confidence interval (CI), 2.83-9.37), and a statistically significant negative association with cardia cancer (OR, 0.40; 95% CI, 0.20-0.77). Adjustment for socioeconomic factors and smoking did not materially alter the effect estimates. The association between the infection and non-cardia cancer was stronger for tumors distal to the angulus and tended to be stronger in women than in men. The results were similar across Laurén morphologic subtypes. CONCLUSIONS: These results strengthen the evidence of H. pylori infection as a risk factor in non-cardia gastric cancer. A negative association with H. pylori infection was found for cardia cancer.

Identification of clinical isolates of Mycobacterium spp. by sequence analysis of the 16S ribosomal RNA gene. Experience from a clinical laboratory.

Twenty-one mycobacterial type strains and 334 clinical isolates of mycobacteria were identified by standardized sequence analysis using part of the gene encoding 16S rRNA. Apart from two clinical isolates, the resulting sequences corresponded to previously published sequences. The results of the molecular determinations of the type strains completely overlapped the identities obtained using conventional techniques (cultural characteristics, biochemical tests, commercial DNA probes, and gas chromatographic lipid profiles). Of 323 isolates conventionally identified as slow-growing mycobacteria, 318 (98.5%) were identified to the same species or group level by 16S rDNA sequence analysis, while 6 of the 11 strains of rapid growers obtained a corresponding identity with the two approaches. The sequencing protocol combined with a few cultural characteristics (i.e. growth rate, pigmentation and susceptibility testing) offers a rapid, reliable and usually definite identification of mycobacterial isolates.

Helicobacter pylori--a trigger of reactive arthritis?

Four cases of reactive arthritis (ReA) related to Helicobacter pylori (HP) are presented. These were identified by IgG, IgM and IgA ELISA tests performed on sera obtained from a 2-year prospective study on 186 patients with a clinical picture suggesting ReA as a possible diagnosis. If anti-HP IgM and IgA or IgG were positive, the case was considered related to HP. Three out of four HP ReA patients were originally classified as "possible ReA", i.e. having a clinical picture of ReA but without any identified triggering microorganism. IgG antibodies against cagA and vacA were detected in three and two cases respectively. The HP ReA patients did not present with typical clinical or laboratory features differentiating them from ReA induced by Chlamydia trachomatis (N = 25) or enteropathogenic bacteria (N = 27). However, compared to findings in patients with ReA due to enteropathogenic bacteria the number of active joints was higher (six versus two), duration of arthritis longer (3.9 weeks versus 2 weeks) and the CRP (C-reactive protein) lower (43 versus 59). Our findings suggest that HP may be included in the list of possible arthritis triggering microbes.

[Yellow staphylococci with borderline resistance to methicillin]. / Gule stafylokokker med nedsatt meticillinfølsomhet.

Over the last four years there has been an increase in the incidence of borderlineresistant Staphylococcus aureus isolated from bacteriological samples at the Ullevål University Hospital, Department of Medical Microbiology. Several severe infections caused by these bacteria have been noticed in the Department of Infectious Diseases at Ullevål University Hospital. From December 1994 to April 1997, 24 patients suffering from this type of S. aureus infection were examined with regard to clinical and microbiological outcome. 15 of the patients had hospital-acquired infections, and all except one had acquired the infection in Norway. 13 of the patients had at least one predisposing factor, 50% had received antibiotics (mainly cefalosporins) beforehand. Three of the 24 patients died from the infection. We discuss etiology, identification of groups at risk and management of the infection.

Diagnosis of congenital Toxoplasma gondii infection by polymerase chain reaction (PCR) on amniotic fluid samples. The Norwegian experience.

As part of a screening project for detection of Toxoplasma gondii infection among pregnant women in Norway, nested polymerase chain reaction (PCR) aimed at the detection of T. gondii in amniotic fluid samples was included in the diagnostic routine. The results were compared with the routine criteria for congenital infection: i) T. gondii detected in amniotic fluid or cord blood by mouse inoculation, ii) specific IgM or IgA in serum collected after birth, and/or iii) specific IgG persisting beyond one year of age. The PCR was based on the B1 gene with an internal control gene amplified together with the B1 gene. One hundred and two amniotic fluid samples collected during pregnancy and/or at delivery from 67 pregnant women with serological evidence of primary T. gondii infection were available for examination by both B1-PCR and mouse inoculation. Six samples were positive and 86 samples were negative by both methods (90% concordance). One sample was mouse inoculation positive and B1-PCR negative while nine samples were B1-PCR positive and mouse inoculation negative, of which five were associated with four infants without proven infection. 59%, and 41% of samples associated with infected infants were positive by B1-PCR and mouse inoculation, respectively. The difference was mainly due to a lower detection rate by mouse inoculation after antiparasitic treatment. The specificity of B1-PCR was 94%. Even though B1-PCR performed on amniotic fluid samples did not detect all infected infants, it represented a valuable tool in addition to conventional methods in the diagnosis of congenital T. gondii infection.

Incidence of Toxoplasma gondii infection in 35,940 pregnant women in Norway and pregnancy outcome for infected women.

From 1992 to 1994 a screening program for detection of specific Toxoplasma gondii antibodies involving 35,940 pregnant women was conducted in Norway. For women with serological evidence of primary T. gondii infection, amniocentesis and antiparasitic treatment were offered. The amniotic fluid was examined for T. gondii by PCR and mouse inoculation to detect fetal infection. Infants of infected mothers had clinical and serological follow-up for at least 1 year to detect congenital infection. Of the women 10.9% were infected before the onset of pregnancy. Forty-seven women (0.17% among previously noninfected women) showed evidence of primary infection during pregnancy. The highest incidence was detected (i) among foreign women (0.60%), (ii) in the capital city of Oslo (0.46%), and (iii) in the first trimester (0.29%). Congenital infection was detected in 11 infants, giving a transmission rate of 23% overall, 13% in the first trimester, 29% in the second, and 50% in the third. During the 1-year follow-up period only one infant, born to an untreated mother, was found to be clinically affected (unilateral chorioretinitis and loss of vision). At the beginning of pregnancy 0.6% of the previously uninfected women were falsely identified as positive by the Platelia Toxo-IgM test, the percentage increasing to 1.3% at the end of pregnancy. Of the women infected prior to pregnancy 6.8% had persisting specific immunoglobulin M (IgM). A positive specific-IgM result had a low predictive value for identifying primary T. gondii infection.

Prevalence of Toxoplasma gondii specific immunoglobulin G antibodies among pregnant women in Norway.

During one year from June 1992 serum IgG antibodies to Toxoplasma gondii among 35,940 pregnant women were measured in a cross-sectional study conducted in Norway. The overall prevalence was 10.9%. The lowest prevalences were detected in the north (6.7%) and in the inland counties (8.2%). A significantly higher prevalence was detected in the southern counties (13.4%) where a mild, coastal climate prevails. Women with foreign names had a higher prevalence (22.6%) than women with Norwegian names (10.0%). The high prevalence among women living in the capital city (Oslo) as compared to other cities and rural areas (13.2% vs. 10.1% and 10.2% respectively), was explained by the higher proportion of foreign women in Oslo. Prevalence significantly increased with age in women over 34 years old. This increase was only detected among women with Norwegian names. An increase in prevalence according to number of children was detected. Women without children had a prevalence of 8.8% while women with three children or more had a prevalence of 14.9%. Multivariate analyses showed that being seropositive was independently associated with county of residence, age, nationality and number of children.

Interlaboratory comparison of polymerase chain reaction for the detection of Toxoplasma gondii DNA added to samples of amniotic fluid.

To investigate the accuracy of the polymerase chain reaction (PCR) method for the detection of Toxoplasma gondii in clinical specimens, aliquots of amniotic fluid to which known amounts of Toxoplasma gondii DNA had been added were tested by five European Centres. Four laboratories were able to detect DNA at levels equivalent to ten tachyzoites or less, including two that detected DNA equivalent to a single parasite. Two laboratories erroneously found one of eight negative control samples to be positive. These findings confirm that the high level of sensitivity associated with the PCR method can be readily achieved under routine laboratory conditions, but they also underscore the potential for both false-positive and false-negative findings to occur. Furthermore, the results confirm the urgent need for an external quality assurance scheme to support laboratories employing PCR in a clinical context for the detection of Toxoplasma gondii.

Risk factors for Toxoplasma gondii infection in pregnancy. Results of a prospective case-control study in Norway.

From 1992 to 1994, a prospective case-control study designed to identify preventable risk factors for Toxoplasma gondii infection in pregnancy was conducted in Norway. Case-patients were identified through a serologic screening program encompassing 37,000 pregnant women and through sporadic antenatal testing for Toxoplasma infection. A total of 63 pregnant women with serologic evidence of recent primary T. gondii infection and 128 seronegative control women matched by age, stage of pregnancy, expected date of delivery, and geographic area were enrolled. The following factors were found to be independently associated with an increased risk of maternal infection in conditional logistic regression analysis (in order of decreasing attributable fractions): 1) eating raw or undercooked minced meat products (odds ratio (OR) = 4.1, p = 0.007); 2) eating unwashed raw vegetables or fruits (OR = 2.4, p = 0.03); 3) eating raw or undercooked mutton (OR = 11.4, p = 0.005); 4) eating raw or undercooked pork (OR = 3.4, p = 0.03); 5) cleaning the cat litter box (OR = 5.5, p = 0.02); and 6) washing the kitchen knives infrequently after preparation of raw meat, prior to handling another food item (OR = 7.3, p = 0.04). In univariate analysis, travelling to countries outside of Scandinavia was identified as a significant risk factor, but this variable was not independently associated with infection after data were controlled for factors more directly related to the modes of infection.