Biomedical subjects

S Ringertz

Publications and source records attributed to S Ringertz.

At least 19 recordsLinked to original sources

PubMed1999

Etiology of pneumonia, sepsis and meningitis in infants younger than three months of age in Ethiopia.

METHODS: Within a multicenter study coordinated by WHO, an investigation of the etiologic agents of pneumonia, sepsis and meningitis was performed among infants younger than 3 months of age seen at the Ethio-Swedish Children's Hospital in Addis Ababa for a period of 2 years. Of the 816 infants enrolled 405 had clinical indications for investigation. RESULTS: There were a total of 41 isolates from blood cultures from 40 infants. The study showed that the traditionally known acute respiratory infection pathogen Streptococcus pneumoniae was most common in this extended neonatal age group, found in 10 of 41 blood isolates. Streptococcus pyogenes was a common pathogen in this setting (9 of 41 blood isolates), whereas Salmonella group B was found in 5 of 41 isolates. Streptococcus agalactiae, which is a common pathogen in developed countries, was absent. A study of the susceptibility pattern of these organisms suggests that a combination of ampicillin with an aminoglycoside is adequate for initial treatment of these serious bacterial infections, but the combination is not optimal for the treatment of Salmonella infections. Among 202 infants on whom immunofluorescent antibody studies for viruses were performed based on nasopharyngeal aspirates, respiratory syncytial virus was found in 57 (28%) infants, and Chlamydia trachomatis was isolated in 32 (15.8%) of 203 infants.

Bacteria↗

PubMed1999

CT and MR imaging of the paranasal sinuses in cystic fibrosis. Correlation with microbiological and histopathological results.

PURPOSE: To compare CT and MR findings of the paranasal sinuses in patients with cystic fibrosis (CF) with microbiology and histopathology. Further, to compare microbiology from the maxillary sinuses, nasopharynx and sputum. MATERIAL AND METHODS: CT and MR imaging of the paranasal sinuses were performed in 10 CF patients. Endoscopy and maxillary sinus aspirates were obtained (guided by the MR findings) and analyzed microbiologically and histologically. Samples from the nasopharynx and sputum were analyzed microbiologically. RESULTS: CT and MR were equal in displaying the extent of soft tissue masses, which at CT were homogeneous, while MR showed heterogeneous signals. MR images also demonstrated circumscribed areas with signal void at the STIR sequence with corresponding high to intermediate signal at the T1-weighted sequence. P. aeruginosa was frequently cultured from these areas which we named the "black hole sign". Maxillary sinus cultures revealed the same bacteria as nasopharynx and sputum cultures combined. CONCLUSION: MR images were superior to CT in differentiating soft tissue masses in the paranasal sinuses in CF patients. Bacteria with potential for specialized iron uptake mechanisms were present in areas with signal void at the STIR sequence. Our hypothesis is that the MR "black hole sign" can be explained by paramagnetic properties related to bacterial agents.

Adult↗

PubMed1998

Sulfonamide resistance in Streptococcus pyogenes is associated with differences in the amino acid sequence of its chromosomal dihydropteroate synthase.

Sulfonamide resistance in recent isolates of Streptococcus pyogenes was found to be associated with alterations of the chromosomally encoded dihydropteroate synthase (DHPS). There were 111 different nucleotides (13.8%) in the genes found in susceptible and resistant isolates, respectively, resulting in 30 amino acid changes (11.3%). These substantial changes suggested the possibility of a foreign origin of the resistance gene, in parallel to what has already been found for sulfonamide resistance in Neisseria meningitidis. The gene encoding DHPS was linked to at least three other genes encoding enzymes of the folate pathway. These genes were in the order GTP cyclohydrolase, dihydropteroate synthase, dihydroneopterin aldolase, and hydroxymethyldihydropterin pyrophosphokinase. The nucleotide differences in genes from resistant and susceptible strains extended from the beginning of the GTP cyclohydrolase gene to the end of the gene encoding DHPS, an additional indication for gene transfer in the development of resistance. Kinetic measurements established different affinities for sulfathiazole for DHPS enzymes isolated from resistant and susceptible strains.

Amino Acid Sequence↗

PubMed1997

Viridans streptococci in blood cultures. Can we see any patterns of species related to patient category? Review of 229 cases of positive cultures with viridans streptococci.

We present a review of 229 blood cultures with viridans streptococci collected during a period of eight and a half years from 1986 to 1994 at a teaching hospital in Sweden. The clinical significance of the growth of viridans streptococci is always uncertain, since these bacteria can be contaminants from the skin flora. Growth in more than one culture bottle strengthens the clinical value of the finding. The question was whether species identification might also help in the assessment of the clinical relevance of the finding. The results show that Streptococcus mitis occurs significantly more frequently in blood cultures from the departments dealing with cancer patients. Even with polymicrobial growth in blood cultures, S. mitis should be considered a pathogen of clinical relevance, not a contaminant.

Blood↗

PubMed1997

Antimicrobial susceptibility testing in Sweden. II. Species-related zone diameter breakpoints to avoid interpretive errors and guard against unrecognized evolution of resistance.

The Swedish Reference Group for Antibiotics appointed a subcommittee on methodology (SRGA-M) in 1987 to investigate ways of defining interpretive breakpoints for antimicrobial susceptibility testing. The minimum inhibitory concentration (MIC) breakpoints for susceptibility categories are mainly based on pharmacological properties of the antibiotic, and they are, with few exceptions, valid for all species. However, for several species the MIC breakpoints have failed to distinguish strains with reduced susceptibility from normal susceptible strains. Disk diffusion is the routine method for susceptibility testing in Sweden. Studies of distribution of MICs and zone diameters for clinically important bacterial species have resulted in an emphasis on resistance rather than on susceptibility. The SRGA-M chose to place the zone diameter breakpoints close to the native (often susceptible) population of each species or group of related species. Such species-related zone diameter breakpoints used for susceptibility categories no longer correspond to the pharmacological MIC breakpoints, but divide each species into the fully susceptible (native) population and into those isolates/populations that have acquired a resistance mechanism, resulting in high- or low-grade resistance. By this method the risk of reports of false susceptibility is minimized and early detection of the emergence of antibiotic resistance is ensured.

Anti-Bacterial Agents↗

PubMed1997

Antimicrobial susceptibility testing in Sweden. IV. Quality assurance.

The performance of susceptibility testing depends on high-quality material (disks and media), good laboratory practice (robust methodology and correct handling of material) and antimicrobial breakpoints being set in such a way that they allow for some intralaboratory variation. Thus, breakpoints must not divide homogeneous bacterial populations. Routine susceptibility testing should be checked with both internal and external quality control programs. The internal quality control should be designed to demonstrate the importance of minimizing random errors and to rapidly disclose systematic errors. This can be achieved either through the repeated testing of defined control strains or by systematic comparison of histograms of routine zone diameters with reference histograms supplied by the Swedish Reference Group for Antibiotics (SRGA and SRGA-M). The SRGA-M offers an external quality control program which by its design also functions as an epidemiological surveillance program. The quality control programs are supported by an educational program for laboratory personnel.

Anti-Bacterial Agents↗

PubMed1996

Pseudomonas aeruginosa in otitis externa. A particular variety of the bacteria?

BACKGROUND: Pseudomonas aeruginosa rarely affects the epithelium in healthy persons except for the external ear canal, raising the possibility that P aeruginosa in otitis externa is a specific variety that displays particular characteristics. DESIGN: A cohort study was designed to outline distinct characteristics of P aeruginosa in otitis externa compared with P aeruginosa in other infections. The study period was October 1, 1994, to March 27, 1995. PATIENTS: Isolates of P aeruginosa from nonhospitalized patients were collected at the bacteriological laboratory at Karolinska Hospital, Stockholm, Sweden; there were 53 strains of P aeruginosa isolated from otitis externa and 59 strains of P aeruginosa from varicose ulcers and urinary tract infections. METHODS: Pseudomonas aeruginosa was characterized by pigmentation, growth habits, production of mucoid, and biochemical characteristics. RESULTS: Pseudomonas aeruginosa in otitis externa produced less pyocyanin and less urease and exhibited no mucoid-producing strains. CONCLUSIONS: Pseudomonas aeruginosa in otitis externa displayed fewer of the usual biochemical features of the species than did the strains isolated from other infections. Some of these features, such as the production of pyocyanin, are influenced by nutritional factors; strains found in otitis externa probably represent the type of strains present in the natural habitat in water, as opposed to the strains that have adapted to the environment of other human infections. Increased knowledge of the characteristics of the strains found in otitis externa is important in understanding the pathogenesis of the disease and why P aeruginosa is the dominant infectious agent in otitis externa.

Humans↗

PubMed1996

Imipenem/cilastatin monotherapy as salvage treatment in febrile neutropenic patients.

Imipenem/cilastatin (I/C) monotherapy was used as salvage treatment in 55 neutropenic patients (58 fever episodes) after treatment failure on first-line antibiotic therapy. Successful antibiotic treatment was defined as eradication of all signs, symptoms and microbiologic evidence of infection on I/C monotherapy alone. Twenty-five out of the 58 episodes (43%) were classified as success, 6 episodes (10%) as initial response but the regimen had to be modified (amphotericin B was added) and 27 episodes (47%) as failures. In episodes with documented infections 9 out of 23 (39%) were classified as success. All patients survived during the first 72 hours after change to I/C therapy. One patient had to discontinue I/C due to a skin rash. In conclusion, the use of a treatment algorithm with I/C monotherapy as second-line treatment was safe and effective. Other antimicrobial agents, most often vancomycin and/or amphotericin B, had to be added in half of the patients.

Adolescent↗

PubMed1996

Trimethoprim-sulfamethoxazole plus amikacin versus ceftazidime monotherapy as empirical treatment in patients with neutropenia and fever.

In a prospective randomized comparison, 217 episodes of fever (oral temperature > 38.5 degrees C on 1, or 38.0 degrees C on 2 occasions with a minimum interval of 4 h between recordings) during neutropenia (neutrophil count < 0.5 x 10(9)/I), patients were empirically treated with trimethoprim-sulfamethoxazole plus amikacin (TMP/SMZ plus AMI) or ceftazidime. Successful antibiotic treatment was defined as eradication of all signs, symptoms and microbiological evidence of infection on the primary therapy alone. The overall success rate did not differ between the 2 treatment groups: 31/102 (30%; 21-39%, 95% confidence interval, CI) for TMP/SMZ plus AMI and 41/115 (36%; 27-44%) for ceftazidime (difference 0.06 +/- 0.13, 95% CI). The corresponding numbers for documented infections were 12/50 (24%; 12-36%) and 14/60 (23%; 12-35%), respectively (difference 0.01 +/- 0.16). One patient in the TMP/SMZ plus AMI group and 2 patients in the ceftazidime group died from Gram-negative bacteraemias within 72 h. No other early deaths were observed. Antibiotics were changed due to adverse events in 2 episodes of each treatment group. In conclusion, this study demonstrates that TMP/SMZ plus AMI combination is comparable (i.e. a difference of < 20%) to ceftazidime monotherapy with regard to efficacy and safety in haematological patients with severe neutropenia. Both regimens require frequent modifications, particularly in bacteraemic fever episodes. However, in centres with a low frequency of isolation of Pseudomonas and especially of multi-resistent Pseudomonas strains, TMP/SMZ plus AMI offers an inexpensive alternative for the empirical treatment of febrile neutropenia.

Adolescent↗

PubMed1995

Change of central venous catheter dressings twice a week is superior to once a week in patients with haematological malignancies.

Thirty-two consecutive patients with haematological disorders, in need of a permanent central venous catheter (CVC) were randomly allocated to have their CVC bandages (Tegaderm) changed once (OAW, n = 20) or twice (TAW, n = 19) a week. The two randomization arms were balanced in respect of age, sex, and underlying disease. The exit site of the CVC was inspected daily through the transparent bandage and erythema was noted. If severe erythema occurred, daily wet gauze dressings were applied. Samples for bacterial cultures were taken from the exit site of the CVC at every change of bandages. There was no difference in complications leading to removal of the CVC between the two groups (7/20 OAW vs. 7/19 TAW) or in CVC survival-time (P = 0.4). However, the OAW group had more positive CVC tip cultures (OAW 11/14 vs. TAW 2/9; P < 0.05) and a tendency to: (i) more extra dressings (P = 0.08); (ii) more cultures from the exit skin site showing high numbers of colony forming units (P = 0.07); (iii) shorter time to first exit site infection (P = 0.09); and (iv) more Gram-positive septicaemias (P = 0.08). Both clinical and bacteriological data in this study indicate that changing transparent polyurethane CVC bandages twice a week is superior to once a week.

Adolescent↗

PubMed1995

The virgin population of Neisseria gonorrhoeae in Stockholm has decreased and antimicrobial resistance is increasing.

AIMS: To investigate the evolution of chromosomal and plasmid mediated resistance for ampicillin and tetracycline of N gonorrhoeae strains in Stockholm during 1982-1993. METHODS: A total of 404 gonococcal strains isolated in 1982, 1987, 1990, 1992, 1993 were analysed for minimal inhibitory concentrations (MIC) of ampicillin and tetracycline and for plasmid content. MIC values were determined by the agar dilution method and plasmid preparations were performed using alkaline lysis. To detect additional gonococcal strains with tet(M) plasmids all strains isolated in 1988-1989 and 1991, in all 234 isolates, were analysed retrospectively for MIC values of tetracycline. If an MIC value of > or = 4.0 mg/l was recorded plasmid analysis was performed. RESULTS: Increased proportions of chromosomally mediated resistance to tetracycline (p < 0.001) as well as plasmid mediated resistance to both ampicillin (p < 0.02) and tetracycline were found in the later part of the study. In 1991 the first gonococcus with tet(M) plasmid was isolated in Sweden. The proportion of strains with chromosomally mediated resistance for ampicillin did not change during the study period. The proportion of gonococcal strains with the 39 kb conjugative plasmid was increased in the later part of the study. CONCLUSIONS: The increased proportion of N gonorrhoeae strains with resistance to ampicillin and tetracycline is most likely due to importation of strains from areas with high prevalence of antibiotic resistant gonococci. The proportion of N gonorrhoeae strains with tet(M) plasmids is low in Sweden, but might increase in the same way as the proportion of PPNG strains has increased during 1982-1993.

Ampicillin Resistance↗

PubMed1994

Neonatal Ureaplasma urealyticum colonization and chronic lung disease.

We studied Ureaplasma urealyticum colonization in 93 intubated infants (gestational ages 23-40 weeks) in our neonatal intensive care unit by obtaining cultures from endotracheal aspirate and nasopharynx during their first week of life. Eighteen infants had positive cultures, giving a colonization rate of 19%. No infant more than 30 weeks' gestation had a positive culture. The infants with positive cultures had a significantly lower gestational age and birth weight (p < 0.009 and p < 0.005), with a colonization rate of 33% in infants less than 1000 g. Among the infants with positive cultures, 10 of 17 developed chronic lung disease in contrast with 21 of 72 infants with negative cultures. The development of chronic lung disease and duration of oxygen requirement was strongly associated with immaturity but only weakly with Ureaplasma urealyticum.

Chronic Disease↗

PubMed1993

Use of a DNA hybridization method to verify results of screening for methicillin resistance in staphylococci.

Tests were performed by the disk diffusion method, agar dilution method and the E test to determine the susceptibility to methicillin and oxacillin of clinical isolates and control strains of Staphylococcus aureus (n = 106) and coagulase-negative species (n = 131). Results were compared with those of a dot blot DNA hybridization test, in which the mecA gene was detected using an oligonucleotide probe selected from the mecA gene. Among the Staphylococcus aureus strains the mecA gene was found in all but two strains inhibited by > or = 8 mg/l of methicillin and all but two strains inhibited by > or = 4 mg/l of oxacillin. A disk test using either 1 microgram oxacillin or 10 micrograms methicillin and a tentative resistance breakpoint of < or = 10 mm gave the best agreement with the hybridization test. For coagulase-negative staphylococci 34 of 35 strains inhibited by > or = 8 mg/l methicillin hybridized with the probe as well as 58 of 82 strains inhibited by 1-4 mg/l; 93 of 97 strains inhibited by > or = 0.5 mg/l oxacillin were also positive in the probe test. Using the 1 microgram oxacillin disk and a resistance breakpoint of < or = 10 mm good agreement was obtained between results of the disk diffusion and DNA hybridization tests. It is suggested that this genotypic method for detection of methicillin resistance is used as a reference method for routine methods.

Base Sequence↗

PubMed1993

Prevalence of potential respiratory disease bacteria in children in Ethiopia. Antimicrobial susceptibility of the pathogens and use of antibiotics among the children.

Acute respiratory infections are primary causes of morbidity and mortality in children in developing countries. This project was designed to investigate antimicrobial susceptibility of respiratory tract pathogens isolated from children in rural and city areas, and to contribute to the rational choice of antibiotics for respiratory tract infections in children in Ethiopia. Nasopharynx and throat cultures were taken from all children under five years of age in three study areas representing different levels of contact with health care and accessibility to modern drugs, such as antibiotics. In all, 1126 children were cultured. Haemophilus influenzae and Streptococcus pneumoniae were both found in 85-90% of the children, and beta-haemolytic streptococci group A in 12%. The level of antimicrobial resistance was low. None of the 954 strains of H. influenzae were beta-lactamase producers. Pneumococci were susceptible to penicillin. The use of antibiotics was also low; 11 of 1126 children had antibiotics on the day of culture or the day before. The choice of antibiotics was not limited by resistance, and emphasis could be put on low cost, minimizing adverse drug reactions and ecological impact.

Anti-Bacterial Agents↗

PubMed1992

Colonization with coagulase-negative staphylococci in two neonatal units.

Episodes of septicaemia due to coagulase-negative staphylococci (CNS) were more frequent in a level III than in a level II neonatal unit in Stockholm, Sweden. Colonization with CNS during the first 2 weeks of life was investigated in 10 infants from each unit. As the use of antibiotics differed between the two units, the aim was to correlate colonization and antimicrobial resistance patterns to antibiotic usage. Antimicrobial susceptibility of CNS to isoxazolylpenicillins, co-trimoxazole, erythromycin, clindamycin, chloramphenicol and gentamicin was determined. Selected isolates were typed with restriction endonuclease analysis of plasmid DNA and of genomic DNA. Infants were frequently colonized with multiple strains and species of CNS, and transmission of strains from patient to patient occurred within the unit. Qualitative and quantitative differences in antibiotic use were not correlated with colonization. The prevalence of resistant isolates, mostly of Staphylococcus haemolyticus, was higher in the level II unit with lower use of antibiotics. Staphylococcus epidermidis, which is generally more virulent, prevailed in the level III unit, where there were more severely ill children and invasive procedures were more frequently performed.

Anti-Bacterial Agents↗

PubMed1991

Nosocomial Staphylococcus epidermidis septicaemia among very low birth weight neonates in an intensive care unit.

A cluster of cases of septicaemia caused by coagulase-negative staphylococci was observed among the infants at the Neonatal Intensive Care Unit (NICU) of the Karolinska Hospital in May 1987. The presence of a unique antibiogram among the blood culture isolates prompted an investigation to determine whether an epidemic strain existed or not, using antibiogram, biotyping and plasmid profiles as epidemiological markers. All 14 isolates with a unique antibiogram were investigated, and 22 isolates without the unique antibiogram served as controls. Of the 14 isolates, 11 were Staphylococcus epidermidis and had similar plasmid patterns. Of the 22 control isolates, 15 were S. epidermidis, and none had the special plasmid pattern nor any other recurring plasmid patterns. The use of plasmid profile analysis together with antibiograms thus identified a possible epidemic strain of S. epidermidis which may have been responsible for the upsurge of septicaemia cases at the NICU. The presence of an epidemic strain implies that hospital cross infection control could be important in preventing neonatal septicaemia caused by S. epidermidis.

Coagulase↗

PubMed1991

The role of a commercial latex agglutination test in the diagnosis of group B streptococcal infection in neonates.

An open prospective multicenter study was conducted in order to evaluate the Wellcogen Strep B latex agglutination test in the diagnosis of group B streptococcal (GBS) infections in neonates. Twenty-three (5.9%) of 391 urine specimens and 5 (1.2%) of 404 sera assayed were positive. The results of the urine tests corresponded to a sensitivity of 0.78 for bacteremic, 0.50 for non-bacteremic and 0.53 for all GBS associated (bacteremic, non-bacteremic and suspected) infections. After 20-25-fold concentration of urine specimens the sensitivity increased to 1.0 for bacteremic, 0.67 for non-bacteremic and 0.78 for all GBS associated infections. The specificity of the test was high (0.93 for concentrated urines), and the predictive value of a positive test (Pvpos) was 0.68. A positive latex test was highly predictive of positive surface cultures for GBS (Pv pos = 0.83 after concentration).

C-Reactive Protein↗

PubMed1991

Routine semiquantitative cultures and central venous catheter-related bacteremia.

Semiquantitative cultures were compared with blood cultures during one year in order to see if the routine use of a semiquantitative catheter culture method (SQC) in unselected patients can detect or predict infection associated with central venous catheters. Catheter infection, i.e. greater than or equal to 15 colony forming units (cfu) per plate, occurred in 137 of 542 catheter tips (25%), mainly with coagulase-negative staphylococci. Catheter-associated bacteremia occurred in 17 of 93 cases (18%) where blood cultures had been drawn. In 15 of these, the catheter tip grew greater than or equal to 15 cfu. The predictive value for bacteremia of a positive SQC was only 21%. SQC is not a suitable method for the detection of catheter-associated bacteremia, but may be an indicator of the standard of central venous catheter hygiene.

Bacteriological Techniques↗