Increasing incidence but decreasing in-hospital mortality of adult Staphylococcus aureus bacteraemia between 1981 and 2000.

Staphylococcus aureus is a leading cause of bacteraemia. This study analysed temporal trends from 18,702 adult cases of S. aureus bacteraemia in Denmark between 1981 and 2000. After stratification for mode of acquisition, 57% of cases were hospital-acquired (HA), 28% were community-acquired (CA) and 15% were of undetermined acquisition (UA). Incidence rates increased from 18.2 to 30.5 cases/100,000 population. Annual rates increased by 6.4% for CA, by 2.2% for HA and by 3.6% for UA cases, respectively. Case-mortality associated with HA bacteraemia decreased from 36.2% to 20.7% (43% rate reduction, p 0.0001), compared with a decrease from 34.5% to 26.5% (23% rate reduction, p 0.0001) for CA bacteraemia. Following multivariate analysis, age, pneumonia, endocarditis and chronic illness were associated with increased mortality, regardless of the mode of acquisition. Overall, mortality associated with S. aureus bacteraemia declined significantly between 1981 and 2000, but incidence rates doubled, so that the total number of deaths increased. These data emphasise the public health importance of S. aureus bacteraemia and the need for further preventive measures and improved care in order to reduce incidence rates and improve outcomes.

Hearing loss and cochlear damage in experimental pneumococcal meningitis, with special reference to the role of neutrophil granulocytes.

Hearing loss is a well-known sequelae from meningitis, affecting up to 25% of survivors. However, the principal components of the infectious and inflammatory reaction responsible for the sensorineural hearing loss remain to be identified. The present study aimed to investigate the impact of an augmented neutrophil response on the development of hearing loss and cochlear damage in a model of experimental pneumococcal meningitis in rats. Hearing loss and cochlear damage were assessed by distortion product oto-acoustic emissions (DPOAE), auditory brainstem response (ABR) and histopathology in rats treated with ceftriaxone 28 h after infection. Rats were treated with Granulocyte Colony Stimulating Factor (G-CSF) initiated prior to infection, 28 h after infection or with ceftriaxone only. Rats were followed for 7 days, and assessment of hearing was performed before infection and 24 h and day 8 after infection. Pretreatment with G-CSF increased hearing loss 24 h after infection and on day 8 compared to untreated rats (Mann-Whitney, P = 0.012 and P = 0.013 respectively). The increased sensorineural hearing loss at day 8 was associated with significantly decreased spiral ganglion cell counts (P = 0.0006), increased damage to the organ of Corti (P = 0.007), increased areas of inflammatory infiltrates (P = 0.02) and increased white blood cell (WBC) counts in cerebrospinal fluid on day 8 after infection (P = 0.0084). Initiation of G-CSF 28 h after infection did not significantly affect hearing loss or cochlear pathology compared to controls. In conclusion, the inflammatory host reaction contributes significantly to the development of hearing loss in experimental meningitis.

Simple, rapid latex agglutination test for serotyping of pneumococci (Pneumotest-Latex).

The "gold standard" for epidemiological typing of Streptococcus pneumoniae (pneumococcus) is the capsular reaction test (Neufeld test) with antisera against the 90 pneumococcal polysaccharide capsules, i.e., serotyping. The method is labor intensive and requires a certain level of experience to be performed satisfactory, and thus it has been restricted for use in specialized reference or research laboratories. Surveillance of the serotype distribution of pneumococci that cause infections is important to secure an optimal composition of pneumococcal vaccines and to monitor antibiotic resistance in pneumococci. At Statens Serum Institut, a simple latex agglutination test for serotyping of pneumococci has been developed. The Pneumotest-Latex kit consists of 14 different pooled pneumococcus antisera (pools A to I and pools P to T) applied to latex particles. In a blind test of 352 isolates (with all 90 serotypes represented), 336 (95.5%) were typed or grouped correctly by the Pneumotest-Latex; in addition, 2 (7%) of 30 strains regarded as nontypeable or rough strains were serotyped, and the serotypes of these two isolates were confirmed by the capsular reaction test with type-specific antisera. The Pneumotest-Latex seems to be a sensitive method for serotyping or grouping of the majority of pneumococcal strains. By use of this ready-to-perform latex agglutination kit (Pneumotest-Latex), serotyping of pneumococci can gain more ground as a tool in prevention of pneumococcal diseases.

Urinary concentrations and urine ex-vivo effect of mecillinam and sulphamethizole.

Healthy adult volunteers received 1 g of sulphamethizole orally (n = 10) and later 400 mg of pivmecillinam (274 mg of mecillinam) (n = 9). All urine was collected in defined periods over 24 h, and the drug concentrations in urine were determined. For sulphamethizole, the maximum urine concentration for seven subjects was reached in 0-3 h, and for the remaining three in 3-6 h. For mecillinam, eight of the nine subjects attained a maximum urine concentration in 0-3 h, after which the concentration declined rapidly for six subjects in 3-6 h. Strains of Escherichia coli with different MICs for sulphamethizole and mecillinam were exposed to collected urine for 2.5 h and 5 h. The results indicated that a sensitive E. coli population should be suppressed by sulphamethizole in urine for two-thirds of the time (with 1 g twice-daily) and by mecillinam in urine throughout the 24-h period (with 400 mg three times a day). There was a slight but significant correlation between the ex-vivo effect (Delta log10 CFU/mL) and the log10 concentration/MIC ratio after exposure to sulphamethizole for 5 h (r2 = 0.27, p < 0.0001), and a significant correlation between the variables with mecillinam (r2 = 0.66, p < 0.0001).

Effects of sulfamethizole and amdinocillin against Escherichia coli strains (with various susceptibilities) in an ascending urinary tract infection mouse model.

Resistance to antibiotics used for the treatment of urinary tract infections (UTIs) is increasing worldwide. The impact of in vitro resistance on clinical outcome in UTIs requires further study, since most studies of both humans and animals have evaluated only the efficacy of antibiotics toward bacteria susceptible in vitro. We were interested in evaluating the relationship between the in vitro antibacterial effect and the in vivo efficacy after antibiotic treatment. We simulated a natural ascending UTI by use of the ascending UTI mouse model and used Escherichia coli strains with various susceptibilities to amdinocillin (mecillinam) and sulfamethizole. Mice were treated for 3 days with antibiotic doses approximating human urinary tract concentrations after a standard oral dose. For a susceptible strain (MIC, 0.5 micro g/ml) and a resistant strain (MIC, 128 micro g/ml), respectively, there were significant reductions in bacterial counts in the urine, bladder, and kidneys after treatment with amdinocillin, whereas for a strain for which the MIC was 16 micro g/ml, there was a significant reduction in bacterial counts in the kidneys only (P < 0.05). Treatment with sulfamethizole resulted in a significant reduction in bacterial counts in all samples from a susceptible strain (MIC, 128 micro g/ml) and a resistant strain (MIC, 512 micro g/ml). Infection with a sulII gene-positive strain (MIC, >2,048 micro g/ml) could not be treated with sulfamethizole, as no effect could be demonstrated in the urine, bladder, or kidneys. For amdinocillin, there was no clear-cut relationship between the in vitro susceptibility and the in vivo outcome, while for sulfamethizole, we found a relationship between the MIC for the strain and the effect in the urinary tract.

Susceptibility of Danish Escherichia coli strains isolated from urinary tract infections and bacteraemia, and distribution of sul genes conferring sulphonamide resistance.

Antibiotic resistance of urinary tract pathogens has increased worldwide. Our aim was to provide information regarding resistance patterns of Escherichia coli in urinary tract infections (UTIs) and E. coli bacteraemia in Denmark. The overall resistance ranged from: ampicillin 20-47%, mecillinam 0-7%, trimethoprim 10-28%, sulfamethizole 22-47% and nitrofurantoin 0-3%. In strains with sulfamethizole MICs > 2048 mg/L, 97% carried sulI, sulII or both genes, with sulII being the most common. Among the sulI gene-positive strains, 96% were intI 1 gene positive.

Evaluation of seven different enzyme-linked immunosorbent assays for serodiagnosis of Staphylococcus aureus bacteremia.

OBJECTIVE: Serologic assays for Staphylococcus aureus antibodies were evaluated regarding their ability to differentiate between uncomplicated and complicated S. aureus bacteremia, between S. aureus and non-S. aureus bacteremia, and between S. aureus and non-S. aureus endocarditis. METHODS: Enzyme-linked immunosorbent assays (ELISAs) were performed to measure Ig G antibodies against seven S. aureus antigens (peptidoglycan, teichoic acid, S. aureus ultrasonicate, whole S. aureus cells, alpha-toxin, lipase and capsular polysaccharide) in 129 patients with S. aureus bacteremia (including 51 with endocarditis), 78 patients with non-S. aureus bacteremia (including 27 with endocarditis) and 100 febrile non-bacteremic controls. RESULTS: Whole-cell ELISA was the most sensitive assay. The specificity of all assays was low. Two different combinations of ELISAs for whole cells, teichoic acid,alpha-toxin, lipase and capsular polysaccharide did distinguish between S. aureus and non-S. aureus endocarditis, but not between uncomplicated and complicated S. aureus bacteremia.

In vitro antimicrobial susceptibility of Aerococcus urinae to 14 antibiotics, and time-kill curves for penicillin, gentamicin and vancomycin.

Aerococcus urinae is a newcomer in clinical and microbiological practice, causing urinary tract infections, bacteraemia/septicaemia and/or endocarditis. This study presents for the first time an evaluation of the activity of a representative panel of antibiotics against a large number of A. urinae isolates. The in vitro susceptibilities (MICs) of 56 isolates of A. urinae to 14 antibiotics were determined by agar dilution. In general, A. urinae isolates showed little inter-isolate variability, and had low MICs of penicillin, amoxicillin, piperacillin, cefepime, vancomycin and rifampicin. High-level aminoglycoside resistance was not found for any of the isolates. Moderate to good activity was seen with quinolones, erythromycin and tetracycline. Isolates from two patients with endocarditis were studied with time-kill curves for penicillin, gentamicin and vancomycin. Penicillin and vancomycin alone exhibited slow or no bactericidal activity against the two strains. When combining either penicillin or vancomycin with gentamicin, rapid bactericidal activity was obtained for both strains with both combinations. The treatment options for A. urinae seem to include penicillins for less severe cases. In severe cases, i.e. endocarditis, the time-kill investigations suggest a beneficial effect of combination with gentamicin. In the penicillin-allergic patient vancomycin in combination with gentamicin represents the most obvious alternative.

Transient intestinal carriage after ingestion of antibiotic-resistant Enterococcus faecium from chicken and pork.

BACKGROUND: Antibiotic-resistant enterococci are often present in retail meats, but it is unclear whether the ingestion of these contaminants leads to sustained intestinal carriage. METHODS: We conducted a randomized, double-blind study in 18 healthy volunteers. Six ingested a mixture of 10(7) colony-forming units (CFU) of two glycopeptide-resistant strains of Enterococcus faecium obtained from chicken purchased at a grocery store, six ingested 10(7) CFU of a streptogramin-resistant strain of E. faecium obtained from a pig at slaughter, and six ingested 10(7) CFU of a glycopeptide-susceptible and streptogramin-susceptible strain of E. faecium from chicken purchased at a grocery store. Suspensions of enterococci were prepared in 250 ml of whole milk and were well within the amounts deemed acceptable by Danish food regulations. Stool samples were collected before exposure, daily for 1 week after ingestion, and at 14 and 35 days. Resistant enterococci in stools were identified by selective culture techniques; further molecular characterization of the organisms was also conducted. RESULTS: At the outset, none of the subjects were colonized with glycopeptide-resistant or streptogramin-resistant E. faecium. After ingestion of the study strains, these same strains were isolated from the stools of all subjects, in various concentrations. The test strain was isolated in stool from 8 of 12 subjects on day 6, and from 1 of 12 on day 14. All stool samples were negative at 35 days. CONCLUSIONS: The ingestion of resistant E. faecium of animal origin leads to detectable concentrations of the resistant strain in stools for up to 14 days after ingestion. The organisms survive gastric passage and multiply.

Correlation of MIC methods and tentative interpretive criteria for disk diffusion susceptibility testing using NCCLS methodology for fusidic acid.

Three hundred and eight staphylococci and 43 Streptococcus pyogenes were tested by agar dilution, microbroth dilution, E-test, and disk diffusion using 5, 10 and 50 microg disks, as outlined by the NCCLS, in order to correlate the different MIC methods and to establish tentative species specific interpretive zone diameter breakpoints for fusidic acid. MIC results of the three methods were comparable. For Staphylococcus aureus, using MIC breakpoints of < or = 0.5 mg/L for susceptible and > or = 2 mg/L for resistant tentative interpretive zone diameters of > or = 20 mm and > or = 21 mm for susceptible and < or = 17 mm and < or = 18 mm for resistant are suggested for the 5 microg and the 10 microg disk, respectively. The 50 microg disk did not separate susceptible from resistant isolates. For streptococci a uniform MIC distribution of 2-8 mg/L was found.

Penicillin pharmacodynamics in four experimental pneumococcal infection models.

Clinical and animal studies indicate that with optimal dosing, penicillin may still be effective against penicillin-nonsusceptible pneumococci (PNSP). The present study examined whether the same strains of penicillin-susceptible pneumococci (PSP) and PNSP differed in their pharmacodynamic responses to penicillin by using comparable penicillin dosing regimens in four animal models: peritonitis, pneumonia, and thigh infection in mice and tissue cage infection in rabbits. Two multidrug-resistant isolates of Streptococcus pneumoniae type 6B were used, one for which the penicillin MIC was 0.016 microg/ml and the other for which the penicillin MIC was 1.0 microg/ml. Two additional strains of PNSP were studied in the rabbit. The animals were treated with five different penicillin regimens resulting in different maximum concentrations of drugs in serum (C(max)s) and times that the concentrations were greater than the MIC (T(>MIC)s). The endpoints were bacterial viability counts after 6 h of treatment in the mice and 24 h of treatment in the rabbits. Similar pharmacodynamic effects were observed in all models. In the mouse models bactericidal activity depended on the T(>MIC) and to a lesser extent on the Cmax/MIC and the generation time but not on the area under the concentration-time curve (AUC)/MIC. Maximal bactericidal activities were similar for both PSP and PNSP, being the highest in the peritoneum and blood (approximately 6 log10 CFU/ml), followed by the thigh (approximately 3 log10 CFU/thigh), and being the lowest in the lung (approximately 1 log10 CFU/lung). In the rabbit model the maximal effect was approximately 6 log10 CFU/ml after 24 h. In the mouse models bactericidal activity became marked when T(>MIC) was > or =65% of the experimental time and C(max) was > or =15 times the MIC, and in the rabbit model bactericidal activity became marked when T(>MIC) was > or =35%, Cmax was > or =5 times the MIC, and the AUC at 24 h/MIC exceeded 25. By optimization of the Cmax/MIC ratio and T(>MIC), the MIC of penicillin for pneumococci can be used to guide therapy and maximize therapeutic efficacy in nonmeningeal infections caused by PNSP.

Treatment with a monocolonal antibody to IL-8 attenuates the pleocytosis in experimental pneumococcal meningitis in rabbits when given intravenously, but not intracisternally.

The role of interleukin (IL)-8 as mediator in the recruitment of leucocytes into the CSF was investigated during experimental pneumococcal meningitis. Rabbits were inoculated intracisternally with approximately 10(6) CFU Streptococcus pneumoniae, and treated (i) intravenously with 5 mg of a monoclonal antibody to IL-8 (n = 7) or 5 mg of an isotype control antibody (n = 6); (ii) intracisternally with anti-IL-8, 100 microg (n = 5), 10 microg (n = 4), 1 microg (n = 4), 0.1 microg (n = 2). Ten rabbits served as untreated control group. Intravenous treatment with anti-IL-8 attenuated the pleocytosis significantly compared to untreated rabbits (P < 0.04) or rabbits treated with an isotype control antibody (P < 0.02). In contrast, intracisternal treatment with anti-IL-8 failed to attenuate the pleocytosis (P > 0.05). These results show, that IL-8 plays an important role in the recruitment of leucocytes during experimental pneumococcal meningitis, and that the functional activity of IL-8 in this process appears to be on the bloodstream side of the microvascular endothelium of the brain.

Inhibition of leukocyte entry into the brain by the selectin blocker fucoidin decreases interleukin-1 (IL-1) levels but increases IL-8 levels in cerebrospinal fluid during experimental pneumococcal meningitis in rabbits.

The polysaccharide fucoidin is a selectin blocker that inhibits leukocyte recruitment into the cerebrospinal fluid (CSF) during experimental pneumococcal meningitis. In the present study, the effect of fucoidin treatment on the release of the proinflammatory cytokines tumor necrosis factor alpha (TNF-alpha), interleukin-1 (IL-1), and IL-8 into the CSF was investigated. Rabbits (n = 7) were treated intravenously with 10 mg of fucoidin/kg of body weight every second hour starting 4 h after intracisternal inoculation of approximately 10(6) CFU of Streptococcus pneumoniae type 3 (untreated control group, n = 7). CSF samples were obtained every second hour during a 16-h study period. Treatment with fucoidin caused a consistent and significant decrease in CSF IL-1 levels (in picograms per milliliter) between 12 and 16 h (0 versus 170, 0 versus 526, and 60 versus 1,467, respectively; P < 0.02). A less consistent decrease in CSF TNF-alpha levels was observed in the fucoidin-treated group, but with no significant difference between the two groups (P > 0.05). In contrast, there was no attenuation in CSF IL-8 levels. Indeed, there was a significant increase in CSF IL-8 levels (in picograms per milliliter) in the fucoidin-treated group at 10 and 12 h (921 versus 574 and 1,397 versus 569, respectively; P < 0.09). In conclusion, our results suggest that blood-derived leukocytes mainly are responsible for the release of IL-1 and to some degree TNF-alpha into the CSF during pneumococcal meningitis, whereas IL-8 may be produced by local cells within the brain.

Pharmacodynamics of glycopeptides in the mouse peritonitis model of Streptococcus pneumoniae or Staphylococcus aureus infection.

The emergence of resistance to various antibiotics in pneumococci leaves the glycopeptides as the only antibiotics against which pneumococci have no resistance mechanism. This situation has led to a renewed interest in the use of glycopeptides. It has not yet been possible to conclude which one or more of the pharmacokinetic or pharmacodynamic (PK/PD) parameters are the most important and best predictors for the effects of treatment with glycopeptides in animal models or in humans. We used the mouse peritonitis model with immunocompetent mice and with Staphylococcus aureus and Streptococcus pneumoniae as infective organisms. A wide spectrum of different treatment regimens with vancomycin and teicoplanin was tested to study the pharmacodynamics of these drugs. In studies in which the single dose that protected 50% of lethally infected mice (ED(50)) was given as one dose or was divided into two doses, survival was significantly decreased when the dose was divided. The only statistically significant correlations between the percentage of survival of the mice after 6 days and each of the PK/PD parameters were for peak concentration (C(max))/MIC and S. aureus and for the free fraction of C(max) (C(max-free))/MIC and S. pneumoniae. For S. pneumoniae, the ED(50) for different dosing regimens increased with the number of doses given; e.g., the single-dose ED(50)s for vancomycin and teicoplanin were 0.65 and 0. 45 mg/kg, respectively, but the ED(50)s for dosing regimens with 2-h doses given for 48 h were 6.79 and 5.67 mg/kg, respectively. In experiments with 39 different vancomycin dosing regimens and 40 different teicoplanin dosing regimens against S. pneumoniae, the different PK/PD parameters were analyzed using logistic regression. The C(max-free)/MIC was one of two parameters that best explained the effect for both drugs; for vancomycin, the other important parameter was the AUC/MIC, and for teicoplanin, the other parameter was the time the free fraction of the drug is above the MIC. The effect analyzed as a function of C(max-free)/MIC disclosed thresholds with shifts from almost no effect to full effect at ratios of five to six for vancomycin and two to three for teicoplanin.

[Staphylococcus aureus endocarditis in Denmark 1982-1991. Clinical picture, complications and antibiotic therapy in non-drug addicts]. / Staphylococcus aureus-endocarditis i Danmark 1982-1991. Klinisk billede, komplikationer og antibiotisk behandling hos ikke-narkomaner.

The central S. aureus surveillance in Denmark made it possible to analyze the clinical features of S. aureus endocarditis in a nation-wide population of non-drug addicts. Almost all cases of bacteraemia with S. aureus are reported to the Staphylococcus laboratory, Copenhagen. The medical records were reviewed in cases from 1982 to 1991 in which the diagnosis of endocarditis was reported or suspected. Two hundred and sixty patients fulfilled the diagnostic criteria. In 83 patients the diagnosis of endocarditis was not suspected clinically. The overall mortality rate among those patients whose disease was diagnosed clinically was 46% and significantly associated with late congestive heart failure, age and involvement of the central nervous system. A more frequent use of echocardiography as a screening method seems essential to improve the prognosis of patients with S. aureus endocarditis. Involvement of the CNS constitutes a relative indication for early valve replacement.

Evaluation of calibrated 1 and 10 microl loops and dipslide as compared to pipettes for detection of low count bacteriuria in vitro.

Criteria for defining urinary tract infection have changed as the importance of low count bacteriuria in patients with symptoms of infection has been recognized. Little has been published, however, regarding the ability of routine laboratory methods to meet this new challenge. We compared 1 microl and 10 microl calibrated plastic loops (Nunc, Denmark), to a commonly used dipslide method (Uricult, Orion, Finland) using a 0.1 ml pipette as the gold standard. Four typical uropathogens, E. coli, P. aeruginosa, S. saprophyticus and E. faecalis, were mixed in pooled human urine in numbers representing low counts, i.e. 10(2), 10(3), and 10(4), together with 10(5) colony-forming units (cfu)/ml, and sampling with the four methods was performed 20 times for each with each bacterium and each dilution. Colony counts showed that in many cases the 1 microl loop did not deposit any bacteria on the agar plate when colony counts were lower than 10(4) cfu/ml. The 10 microl loop constantly deposited 1.5 times higher numbers of bacteria than predicted, which correlated with the results of weighing the amount of water sampled, i.e. 15.24 (1.55) microg (mean (SD)). The dipslide counts correlated with the 10 microl loop although the agar mounts on the slides absorbed water equal to about 200 microl. There were no significant differences in the counts of the four different bacteria. Variation coefficients increased with decreasing volumes sampled, but the 10 microl loop was found sufficiently exact to detect counts from 10(3) to 10(4), since only 10-fold multiples are usually reported for urine cultures.

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.

Evaluation of a new 3-h hybridization method for detecting the mecA gene in Staphylococcus aureus and comparison with existing genotypic and phenotypic susceptibility testing methods.

A new 3-h hybridization assay for detection of the staphylococcal mecA gene and the Staphylococcus aureus nuclease gene was evaluated by comparing the assay with existing genotypic and phenotypic methods. A total of 275 S. aureus strains were tested, including 257 epidemiologically unrelated strains (135 mecA-positive and 122 mecA-negative; collection I), and 18 strains with known borderline resistance to methicillin (collection II). Complete agreement was obtained for both collections when comparing the new assay with genotypic methods. We further evaluated a range of phenotypic susceptibility methods recommended in Europe and/or USA using the presence of the mecA gene as the defining standard. For collection I a high degree of agreement was found for both Etests (256 strains) and the oxacillin screen plate test (255 strains); the degree of agreement was lower for agar dilution methicillin (250 strains) and oxacillin 1 microg discs (239 strains). For the borderline strains a high degree of agreement was only obtained by the oxacillin screen plate test (17 of 18 strains). The other tests were less accurate, in the following order: agar dilution methicillin, Etest methicillin, Etest oxacillin and oxacillin discs with disagreement for four, five, nine and 13 strains, respectively. In conclusion, the new hybridization assay is a rapid and exact method for detecting the mecA gene and the S. aureus nuclease gene. This study confirms that phenotypic tests for methicillin resistance in S. aureus strains creates both false-susceptible and false-resistant results, especially for borderline resistant strains.

Pretreatment with granulocyte colony-stimulating factor attenuates the inflammatory response but not the bacterial load in cerebrospinal fluid during experimental pneumococcal meningitis in rabbits.

A possible immunomodulatory role of granulocyte colony-stimulating factor (G-CSF) was investigated in an experimental pneumococcal meningitis model in rabbits. Animals were pretreated with G-CSF (10 micrograms/kg subcutaneously twice a day) starting 48 h before in vivo and ex vivo experiments, causing a five- to six-fold increase in the peripheral leukocyte level. Meningitis was induced by intracisternal inoculation of approximately 4 x 10(5) CFU of Streptococcus pneumoniae type 3. Neutrophil pleocytosis and interleukin-8 (IL-8) levels were significantly attenuated in G-CSF-pretreated animals compared to untreated animals (P < 0.05). Furthermore, G-CSF pretreatment significantly delayed alterations in cerebrospinal fluid (CSF) tumor necrosis factor alpha and IL-1beta levels, as well as protein and glucose levels (P < 0.05). No difference in CSF bacterial concentrations was found, whereas the blood bacterial concentration was significantly decreased in G-CSF-pretreated animals (P < 0.05). Ex vivo chemotaxis of neutrophils isolated from G-CSF-pretreated animals was significantly decreased compared to that of neutrophils from untreated animals (P < 0.05). In conclusion, G-CSF pretreatment attenuates meningeal inflammation and enhances systemic bacterial killing. Further preclinical studies are required to investigate whether this may affect the clinical course of meningitis and thus whether G-CSF treatment may have a beneficial role in pneumococcal meningitis.