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F Espersen

Publications and source records attributed to F Espersen.

At least 37 records · Page 2Linked to original sources
PubMed1999

Detection of clinical vancomycin-resistant enterococci in Denmark by multiplex PCR and sandwich hybridization.

Since the first cases of human infection with vancomycin-resistant enterococci (VRE) were reported in the late eighties, there has been a dramatic increase in VRE all over the world. So far, there have not been any reports of clinical VRE in Denmark. In this study we have investigated 131 clinically important enterococci sent to Statens Serum Institut from all over Denmark during the period July 1995 to May 1997. The susceptibility to vancomycin, teicoplanin, ampicillin and gentamicin was tested by the agar dilution method. In addition, two methods were developed to detect the different genotypes of glycopeptide resistance described in enterococci: a multiplex PCR assay for detection of vanA, vanB, vanC-1, vanC-2/3 ligase genes including 16S rRNA gene control primers and a sandwich hybridization assay to confirm vanA and vanB PCR-positive strains. The highest frequency of resistance to the tested antibiotics was found in the Enterococcus faecium group. Four strains were found with acquired resistance to glycopeptides: one E. faecium and one E. gallinarum were vanA positive, and two E. faecium isolates were vanB positive. These strains were isolated from different hospitals in different periods of time, and all patients recovered from their infections with VRE. Today, the PCR and sandwich hybridization methods are used for screening of vancomycin-resistant enterococci in humans as part of the Danish surveillance programme.

Ampicillin↗
PubMed1999

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.

Animals↗
PubMed1999

Evaluation of Statens Serum Institut enteric medium for detection of enteric pathogens.

The efficacy of the Statens Serum Institut (SSI) enteric medium for isolation and direct identification of enteric pathogens was evaluated. Six different biochemical reactions can be read by using the SSI enteric medium, allowing direct identification of a range of enteric pathogens. All 248 gram-negative bacterial species that were tested grew on the SSI enteric medium. Only 10 of 248 bacteria (4%) showed discrepant results in the biochemical reactions, and none of these were enteric pathogens. Forty-three of 47 enteric pathogens (92%) produced identical rates of semiquantitative growth on the SSI enteric medium and 5% blood agar, whereas three Vibrio spp. and one Aeromonas spp. showed reduced growth. Gram-positive bacteria did not grow on the SSI enteric medium. Most enteric pathogens had a detection limit of 50 bacteria per ml of feces, but higher numbers of Vibrio spp. and some Shigella spp. were required for detection. The growth rates of 125 enteric pathogens and 12 Yersinia spp. on the SSI enteric medium, xylose lysine deoxycholate (XLD), Hektoen enteric (HE), Salmonella-Shigella (SS), and cefsulodin-irgasan-novobiocin (CIN) agar were compared. Detection rates after application of 200 CFU were 99% for SSI enteric medium, 92% for XLD, 88% for HE, and 82% for SS agar. The 12 Yersinia spp. grew excellently on both the SSI enteric medium and CIN agar. We conclude that the performance of the SSI enteric medium compares favorably to those of other media tested. Its ability to detect Yersinia spp. may limit the number of media needed in the typical laboratory. The direct identification of enteric pathogens on the medium may also provide a more rapid diagnosis.

Culture Media↗
PubMed1999

Randomised trial of pivampicillin plus pivmecillinam vs. pivampicillin in children and young adults with chronic obstructive pulmonary disease and infection with Haemophilus influenzae.

A prospective, randomised, single-blind comparative trial was carried out to determine whether double beta-lactam treatment with pivampicillin plus pivmecillinam is more effective than pivampicillin alone in the treatment of recurrent and chronic lung infections with Haemophilus influenzae in patients with chronic obstructive pulmonary disease (COPD) or cystic fibrosis (CF). Fifty-six children and young adults with COPD or CF were randomised to the clinical study. The patients were allocated at random to receive perorally either pivmecillinam, 40 mg/kg/day, combined with pivampicillin, 50 mg/kg/day, or pivampicillin 50 mg/kg/day alone for 14 days. A cross-over pharmacokinetic study using the same drugs was carried out in 10 CF patients to determine the antibiotic concentrations in serum and sputum after a single dose of each drug. The clinical study showed no significant differences in clinical scoring, lung function tests or adverse events after treatment with pivampicillin plus pivmecillinam or pivampicillin alone. Follow-up microbiological evaluation 2 and 6 weeks after the end of treatment showed that the offending pathogen was eradicated in 68% of the patients treated with pivampicillin plus pivmecillinam and in 67% of the patients treated with pivampicillin alone. Reinfection with another biotype was more common in the combination group (50% vs. 21%) than in the pivampicillin group. In the pharmacokinetic study the median peak serum concentration occurred two hours after intake of tablets. The efficacy of double beta lactam treatment in lung infections with H. influenzae appears to be equivalent to that of ampicillin on clinical lung symptoms, lung function tests, adverse effects and bacteriology.

Adolescent↗
PubMed1998

Bacteremic Staphylococcus aureus spondylitis.

BACKGROUND: The incidence of hematogenous Staphylococcus aureus osteomyelitis of the vertebral column is rapidly increasing and few studies dealing with the diagnosis, treatment, and outcome of this severe disease are available. METHODS: Based on a nationwide registration, the clinical and bacteriological data were reviewed from 133 cases with a positive blood culture for S aureus and symptoms of vertebral osteomyelitis in Denmark for the period 1980 to 1990. RESULTS: The 133 cases of vertebral S aureus osteomyelitis reviewed were mainly community-acquired infections (82%) in older patients (median age, 65 years) and often occurred with underlying diseases. Both symptoms and laboratory values were relatively unspecific. Bone scan methods proved to be more optimal for diagnosis of vertebral S aureus osteomyelitis in the early stages compared with conventional radiography that proved a lack of consistency in the formative stages. The infection was mostly (70%) localized in the lower part of the column. The recurrence rate and rate of therapeutic failure depended on the duration and dosage of penicillinase-stable penicillins, respectively. Patients treated with fusidic acid in addition to penicillinase-stable penicillins had a significantly lower recurrence rate. Based on these findings, we recommend treatment with penicillinase-stable penicillins and fusidic acid for a total of 8 weeks, with a daily dosage of penicillinase-stable penicillins higher than 4 g. CONCLUSIONS: The diagnosis of vertebral S aureus osteomyelitis based on clinical findings is difficult to ascertain. Bone scans are necessary because radiographic methods do not detect disease as early. Treatment with penicillinase-stable penicillins, at least 4 g/d for at least 8 weeks, is recommended.

Adolescent↗
PubMed1998

Resistance to antibiotics used in dermatological practice.

The increased prevalence of bacterial resistance is one of the major problems of medicine today. Antibiotic resistance can be defined as the situation where the minimal inhibitory concentration is greater than the concentration obtainable in vivo. Resistance genes are easily transferred among bacteria, especially bacteria on skin and mucous membranes. In dermatological patients the most important resistance problems are found among staphylococci, Propionibacterium acnes and, to some extent, streptococci. Staphylococcus aureus strains have developed worldwide resistance to penicillin due to betalactamase production in > 90% of cases, and methicillin resistance is now a major problem with resistance levels of > 50% in certain areas of the world. These resistant strains are often multiresistant, and include resistance to erythromycin and tetracycline, with resistance to quinolone developing rapidly. Group A streptococci are still susceptible to penicillin, but increasing problems with erythromycin and tetracycline have been reported. After treatment with both systemic and oral antibiotics, P. acnes develops resistance in more than 50% of cases, and it is estimated that one in four acne patients harbours strains resistant to tetracycline, erythromycin, and clindamycin. To limit the development of antibiotic resistance, it is necessary to establish an antibiotic policy (prescription rules, reimbursement strategy, development of both national and local guidelines, and limitations on non-medical use). Clinicians also need access to rapid diagnostic methods, including resistance testing. This may provide further data for surveillance systems, reporting both antibiotic consumption and resistance levels. The involvement of clinical doctors in teaching and research in this area is probably the most important aspect, along with their involvement in the formulation of national and local guidelines. In the future we may consider it more important to ensure that future patients can be offered antibiotic treatment, rather than focusing on the patient presenting today.

Drug Resistance, Microbial↗
PubMed1998

Pharmacodynamics of penicillin are unaffected by bacterial growth phases of Streptococcus pneumoniae in the mouse peritonitis model.

The correlation between pharmacokinetic parameters and the in-vivo effect of antibiotics in relation to bacterial growth phases was evaluated using the mouse peritonitis model with a penicillin-resistant pneumococcus. Different 8 h dosing regimens were applied, with different total doses and initiated at different times during the bacterial growth phase. The effect was measured as the decline in bacterial counts in the peritoneal cavity. The pharmacokinetic parameters showed major changes during the phases of growth, as the serum elimination of penicillin decreased during the infection. The same effect of dosing regimens was observed in the exponential and stationary phases. In two regimens where T(>MIC) (the time the serum concentration exceeded the MIC) was 50% of the treatment period, a significantly better effect was achieved with a 2 hourly regimen than with a regimen with treatments every 20 min. The T(>MIC) of each dose was shown to be a critical parameter for achieving an effect in all growth phases. The maximum effect of penicillin, a 5-6 x log10 decline in bacterial counts in the peritoneum of the mice, was achieved when T(>MIC) was >50% of the treatment time or longer than approximately 40 min of each dose. The 50% effective dose for protection after a single injection, ED50, was measured in the different phases of the infection and found to increase with the duration of the pneumococcal infection, while mice treated 24 h after challenge were beyond therapeutic range. The correlation between the effect of penicillin and pharmacokinetic parameters appears to follow the same rules during the different in-vivo growth phases of pneumococci.

Animals↗
PubMed1998

Staphylococcus aureus bacteraemia among patients undergoing dialysis--focus on dialysis catheter-related cases.

BACKGROUND: Central venous catheter-related infections are the most common cause of nosocomial S. aureus bacteraemia in Denmark. Central venous catheters are often used for dialysis, and patients on dialysis often run into staphylococcal infections. The purpose of this study was to investigate S. aureus bacteraemia among dialysis patients, especially those related to dialysis catheters. METHODS: This was a retrospective study of 14,387 consecutive S. aureus bacteraemia cases during the period 1976-93, of which 793 cases occurred among dialysis patients. By reviewing the case records, 65 dialysis catheter-related cases were described more thoroughly. RESULTS: The number of S. aureus bacteraemia cases among dialysis patients as a proportion of all cases in Denmark has increased from 5.2 to 14.7% during the study period, but the annual incidence among these patients has been almost stable during the period (median 5.7% (3.2-9.0%)). Patients on dialysis had a lower mortality than other patients with S. aureus bacteraemia (18.9 vs 29.0%), but a four times higher mortality from central venous catheter-related S. aureus bacteraemia (5.3 vs 1.3%, P < 0.001). The mortality from dialysis catheter-related S. aureus bacteraemia was correlated with greater age (median 71 years (57-73) vs median 56.5 years (15-76), P < 0.01) and with septic shock (55.5 vs 7.1%, P < 0.05). Patients on dialysis had a lower frequency of S. aureus endocarditis (3.3 vs 5.4%, P < 0.01) and of S. aureus bone and joint infections (3.3 vs 8.2%, P < 0.001) than other patients. Patients undergoing dialysis had a later onset of catheter-related S. aureus bacteraemia than other patients (median 15 days (1-145) vs 5 days (1-134), P < 0.05). CONCLUSIONS: Patients on dialysis are at a high risk of S. aureus bacteraemia and they have a four times higher mortality from central venous catheter-related S. aureus bacteraemia than other patients. There is need for prospective studies in which patients as well as catheters are followed more thoroughly to study the pathogenesis of dialysis catheter-related infections.

Adult↗
PubMed1998

Comparison of pharmacodynamics of azithromycin and erythromycin in vitro and in vivo.

In this study, we determined the efficacy of various dosing regimens for erythromycin and azithromycin against four pneumococci with different susceptibilities to penicillin in an in vitro pharmacokinetic model and in a mouse peritonitis model. The MIC was 0.03 microg/ml, and the 50% effective doses (determined after one dose) of both drugs were comparable for the four pneumococcal strains and were in the range of 1.83 to 6.22 mg/kg. Dosing experiments with mice, using regimens for azithromycin of one to eight doses/6 h, showed the one-dose regimen to give the best result; of the pharmacodynamic parameters tested (the maximum drug concentration in serum [Cmax], the times that the drug concentration in serum remained above the MIC and above the concentration required for maximum killing, and the area under the concentration time curve), Cmax was the best predictor of outcome. The bacterial counts in mouse blood or peritoneal fluid during the first 24 h after challenge were not correlated to survival of the mice. The serum concentration profiles obtained with mice for the different dosing regimens were simulated in the in vitro pharmacokinetic model. Here as well, the one-dose regimen of azithromycin showed the best result. However, the killing curves in vivo in mouse blood and peritoneal fluid and in the vitro pharmacokinetic model were not similar. The in vitro killing curves showed a decrease of 2 log10 within 2 and 3 h for azithromycin and erythromycin, respectively whereas the in vivo killing curves showed a bacteriostatic effect for both drugs. It is concluded that the results in terms of predictive pharmacodynamic parameters are comparable for the in vitro and in vivo models and that high initial concentrations of azithromycin favor a good outcome.

Animals↗
PubMed1998

Serological diagnosis of experimental Enterococcus faecalis endocarditis.

A modified rat model of endocarditis with catheterization for 2 days was established in female Lewis rats using different inocula of Enterococcus faecalis (strain no. EF 19) in order to measure IgG antibodies in serum during the course of infection. Increasing the inocula intravenously resulted in an increase in the CFU/g vegetation and the CFU/g spleen, the ID50 being about 10 CFU/ml and the ID90 about 1x10(2) CFU/ml. The lowest bacterial inoculum infecting 100% of the rats was 3x10(3) CFU/ml, and for further investigations we used this inoculum size. Rats were sacrificed on day 2, 5, 7, 9, 11 and 28 after infection. The CFU/g vegetation and the CFU/g spleen increased until day 7 and then decreased. Serum samples were collected from 129 rats at different times after challenge. Three different ELISA systems were established to measure the IgG antibody responses: E. faecalis sonicate ELISA (a pool of four sonicates of strain no. EF 10, EF 11, EF 19 and EF 48), E. faecalis whole cell ELISA (strain no. EF 19) and E. faecalis purified cell wall ELISA (strain no. EF 19). An IgG antibody response was detected already on day 2, and except for a minor decrease on day 6/7 the antibody response continued to increase until day 14 (whole cell ELISA and sonicate ELISA) and day 21 (purified cell wall ELISA) when a plateau was reached. Significant increases in IgG antibody responses (p<0.05) were found between groups of rats from days 0-2, 2-8/9 and 8/9-14 in the E. faecalis whole cell and sonicate ELISAs and from days 0-2, 2-10/11 and 10/11-21 in the E. faecalis purified cell wall ELISA. In conclusion, we established a model of endocarditis in rats with catheterization for 2 days and were able to demonstrate an increase in IgG antibodies during the course of infection.

Animals↗
PubMed1997

Neurologic manifestations in Staphylococcus aureus endocarditis: a review of 260 bacteremic cases in nondrug addicts.

PURPOSE: To investigate the neurologic manifestations of infective endocarditis caused by Staphylococcus aureus in a population of nondrug addicts with special emphasis on the clinical presentation, epidemiology, and mortality. PATIENTS AND METHODS: During the period from 1982 to 1991 a total of 8,514 cases of bacteremia with S aureus were reported to the Staphylococcus Laboratory, Copenhagen, Denmark. The medical records of cases of suspected infective endocarditis were retrospectively reviewed and classified according to the new diagnostic criteria for endocarditis proposed by Durack. RESULTS: A total of 260 cases from 63 hospitals fulfilled the diagnostic criteria. Overall, 91 patients (35%) experienced neurologic manifestations. Sixty-one presented with neurologic symptoms, whereas 30 patients developed neurologic complications at various intervals (median: 10 days) after the debut of the disease. The most frequent neurologic manifestation was unilateral hemiparesis, which occurred in 41 patients (45%). Forty-two percent of the females had neurologic manifestations compared to only 30% of the males (P = 0.06). Cases with native mitral valve infection had a significantly higher frequency of neurologic manifestations compared with all other valvular involvement (44% versus 29%, P = 0.02) but the frequency of neurologic complications was only nonsignificantly higher in those patients with native mitral valve infection than in those patients with native aortic valve infection (44% versus 31%, P = 0.10). Only two of the patients with tricuspid valve infection and none of those with congenital heart disorder experienced neurologic manifestations. A neurologic manifestation occurred in 22 (35%) of the 63 episodes in which vegetations were detected on the echocardiograms, compared with 17 (26%) of the 65 episodes without vegetations (P = 0.38). The mortality was 74% in patients with major neurologic manifestations and 56% in patients without neurologic manifestations (P = 0.008). In patients with neurologic complications the mortality was significantly higher among those treated with antibiotics alone as compared with those treated surgically (65 of 81, 80% versus 2 of 10, 20%; P = 0.0003). CONCLUSIONS: In a population of nondrug addicts with infective endocarditis caused by S aureus the following main conclusions can be drawn: neurologic manifestations occur with a higher frequency in patients with native mitral valve infection. The presence of vegetations on echocardiograms is not a risk factor for developing neurologic complications but this conclusion is based on the results of transthoracic echocardiograms performed in only one half of the patients. The majority of the neurologic manifestations occur on presentation or shortly thereafter and the risk of recurrent embolism is low. Mortality is increased in patients with neurologic manifestations. A neurologic event per se may constitute an indication for surgical treatment.

Adult↗
PubMed1997

Increasing frequency of vertebral osteomyelitis following Staphylococcus aureus bacteraemia in Denmark 1980-1990.

From 1980 to 1990, 309 cases of haematogenous osteomyelitis were identified in Denmark. Haematogenous osteomyelitis of the vertebral column increased significantly (P < 0.01) from the first to the second half of the period due to an increased number of patients > 50 years of age with community-acquired infection. Vertebral osteomyelitis differed significantly from osteomyelitis of other bones in accordance to age distribution (median 66 vs. 16 years), male/female ratio (75/71 vs. 105/ 58) and patients with diabetes (13% vs. 6%). We found a higher risk of haematogenous osteomyelitis in patients > 50 years of age and among patients with community-acquired infection. The highest incidence (5%) of vertebral osteomyelitis in Staphylococcus aureus bacteraemia in this age group was found in cases without an identified portal of entry. The highest incidence (34%) of osteomyelitis of other bones was found in community-acquired cases in the age group 1-20 years and without an identified portal of entry. The present study discusses reasons for the continued increase of vertebral osteomyelitis among adults and describes incidence rates and major risk factors for developing haematogenous osteomyelitis among patients with S. aureus bacteraemia. We suggest that the localization of haematogenous S. aureus osteomyelitis is connected with the presence of red bone marrow.

Adolescent↗
PubMed1997

Evaluation of different methods for the detection of methicillin resistance in coagulase-negative staphylococci.

The efficacy of 19 agar diffusion methods for the detection of methicillin resistance among coagulase-negative staphylococci (CoNS) within 24 h was evaluated. A total of 359 CoNS isolates were tested, of which 204 were Staphylococcus epidermidis. In 164 isolates, the presence of mecA was investigated; 61 strains were mecA-positive and 103 were mecA-negative by Southern blot analysis. Based on the best agreement shown with the mecA determination (94%) among four agar dilution assays for determining methicillin MIC, an assay with Columbia agar supplemented with NaCl and incubation with a heavy bacterial inoculum of 10(5)-10(6) cfu/spot was used as the reference MIC method. The best agar diffusion results were obtained with a 1 microg oxacillin disc on Columbia agar with 4.5% NaCl supplement. With this method, 99% of S. epidermidis and 94% of non-S. epidermidis were in agreement with the MIC determination. However, Columbia (without NaCl), Mueller-Hinton and Isosensitest agars were almost as useful when a 1 microg oxacillin disc was used. The zone breakpoints for S. epidermidis were, in general, considerably larger than those for other CoNS species and, consequently, differentiation according to species is recommended. Furthermore, resistance to other antibiotics, such as gentamicin and erythromycin, makes methicillin resistance highly likely.

Bacterial Proteins↗
PubMed1997

Comparison of the effect of cefepime with four cephalosporins against pneumococci with various susceptibilities to penicillin, in vitro and in the mouse peritonitis model.

The purpose of this study was to compare the effect, both in vitro and in vivo, of cefepime with those of four other cephalosporins, namely ceftriaxone, cefotaxime, cefuroxime and cephalothin, against penicillin-resistant pneumococci. One hundred pneumococcal strains, 31 penicillin-susceptible, 30 penicillin-intermediate-resistant and 39 penicillin-resistant pneumococci, were used in MIC studies. Time-kill experiments were carried out for four strains. In the mouse peritonitis model, the dose that gave protection to 50% of mice challenged with a lethal dose of pneumococci (ED50) was determined for three pneumococci and five cephalosporins. The MICs of all five cephalosporins and penicillin correlated significantly with each other. In vitro, the most potent cephalosporins against pneumococci were cefotaxime, ceftriaxone and cefepime, followed by cefuroxime and cephalothin. In time-kill experiments, carried out for four pneumococci, no differences were found in the killing effect of these five cephalosporins in relation to MICs. In the mouse peritonitis model, there was no significant correlation between log(MIC) and log(ED50) for the five cephalosporins against three pneumococci (Spearman's rho = 0.39, P = 0.16). However, if the values for cefepime against the three pneumococci were excluded, there was a significant correlation for the remaining four cephalosporins (Spearman's rho = 0.62, P = 0.04). For all three pneumococci, the ED50s of cefepime were lower than expected from the MICs. It was not possible to explain this beneficial difference in the effect of cefepime in terms of in-vitro bactericidal activities, serum protein binding or pharmacodynamic parameters.

Animals↗
PubMed1997

Coagulase and protein A polymorphisms do not contribute to persistence of nasal colonisation by Staphylococcus aureus.

The nasal carriage rate of Staphylococcus aureus was examined in a longitudinal study of 31 healthy Danish volunteers. Each person was classified as persistent (>8 positive cultures from 10 examinations), an intermittent carrier (50-80% positive cultures) or an ocassional carrier (positive cultures on 10-40% of ocassions only). One hundred and twenty strains from these persons were subjected to phage typing and random amplification of polymorphic DNA (RAPD) analysis. Phage and RAPD typing were in close agreement. RAPD confirmed the spread of a particular S. aureus clone (phage type 95) throughout Denmark. However, no common genotype or phenotype characteristics of S. aureus that could separate persistent from intermittent or incidental colonisers were identified. The immunoglobulin binding protein A and the prothrombin binding coagulase protein are both putative S. aureus virulence or defence factors. Analysis of polymorphisms in the variable repeat regions in the genes for these proteins showed no correlation between the number of repeat units and, consequently, the protein structure with the ability of strains to persist in the human nasal mucosa. The amount of protein A, detectable by its IgG binding activity, appeared not to be correlated to persistence of carriage. Thus protein A and coagulase gene polymorphisms do not seem to play a significant role in the propensity of S. aureus to colonise human nasal epithelium. Furthermore, based on the genetic heterogeneity encountered among the S. aureus strains it is suggested that within the current study population, no single clonal lineage of S. aureus has increased capability to colonise the human nasal epithelium.

Adult↗
PubMed1997

Antimicrobial susceptibility testing of 230 Helicobacter pylori strains: importance of medium, inoculum, and incubation time.

No standardized method of susceptibility testing for Helicobacter pylori is currently available, so before a large agar dilution study comprising 230 H. pylori strains belonging to more than 80 genetically different groups was initiated, we performed a relatively small preliminary study to determine the influences of medium, inoculum density, and incubation time. Seven media were investigated and were primarily evaluated on the basis of their abilities to support growth both semiquantitatively and qualitatively; Iso-Sensitest agar supplemented with 10% horse blood was found to be well suited for the purpose; this was closely followed by Mueller-Hinton agar with 10% horse blood, Mueller-Hinton with 10% sheep blood, and finally, 7% lysed horse blood agar. Investigations of two inoculum densities and two incubation times resulted in recommendations for the use of 10(9) CFU/ml (10[6] CFU/spot) as the inoculum and 72 h as the incubation time. A modest inoculum effect was noted for amoxicillin and metronidazole. By the methodology derived from our preliminary study, the susceptibilities of 230 H. pylori strains to six antibiotics were subsequently determined. The results were generally in accord with those of others, and apart from metronidazole, the MIC of which for approximately 25% of the strains tested was >8 microg/ml, resistance was low in Denmark. The situation might, however, quickly change when and if the number of indications for antibiotic therapy for H. pylori infections increase. Consequently, susceptibility testing of all H. pylori strains is recommended in order to survey the development of resistance, and in our hands the described methodology was relatively easy to perform and the results were easy to read.

Animals↗
PubMed1997

Activities of vancomycin and teicoplanin against penicillin-resistant pneumococci in vitro and in vivo and correlation to pharmacokinetic parameters in the mouse peritonitis model.

The activities of glycopeptides against pneumococci were studied in vitro and in vivo. The MICs of two glycopeptides, vancomycin and teicoplanin, in different media against 10 strains of pneumococci with different susceptibilities to penicillin were determined. The MICs of teicoplanin were four times lower than those of vancomycin in Mueller-Hinton media supplemented with 5% blood, but the MICs were similar in mouse and human sera supplemented with 5% blood. The serum protein binding levels in mouse and human sera were 90% for teicoplanin in both and 25 and 35%, respectively, for vancomycin. The MICs for vancomycin and teicoplanin were only correlated in human serum (P < 0.001). The single doses giving protection to 50% of the animals in the mouse peritonitis model after a lethal challenge of pneumococci, the ED50s, were similar for vancomycin and teicoplanin, between 0.1 and 1 mg/kg of body weight for all 10 strains. The log ED50s were significantly correlated only to the log MICs of teicoplanin determined for mouse serum with 5% blood (P = 0.01) and to the log MICs of vancomycin determined by the E test (P = 0.03). Among the pharmacokinetic parameters analyzed at the ED50s, the most constant parameter was the time for which the drug concentration exceeded the MIC (T(>MIC)) when each drug was considered separately; however, when both drugs were considered together, the maximum concentration of drug in serum (Cmax) varied the least. This indicates that both these parameters are of importance for predicting the effect of the drugs. We conclude that the effect of glycopeptides was not influenced by the penicillin resistance of the pneumococci, either in vitro or in vivo, and that the superior activity of teicoplanin over that of vancomycin in vitro was abolished in vivo, an effect which probably was due to the high serum protein binding of teicoplanin. Both the pharmacokinetic parameters T(>MIC) and Cmax are important predicting the effect of glycopeptides, but the pharmacodynamics of glycopeptides are still not completely elucidated.

Animals↗