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Biomedical subjects

Z Ahmet

Publications and source records attributed to Z Ahmet.

13 recordsLinked to original sources

New PCR primers for the sensitive detection and specific identification of group B beta-hemolytic streptococci in cerebrospinal fluid.

Group B beta-hemolytic streptococci (GBS) are a major cause of sepsis and meningitis in newborn babies. Although penicillin remains an effective treatment, there has been no decline in mortality. The rapid identification of GBS in cerebrospinal fluid (CSF) would improve the diagnosis of meningitis, but data from several previous studies indicate that the sensitivity of polymerase chain reaction (PCR) is not better than culture. Following extraction and precipitation of DNA, we have used semi-nested PCR to amplify a 450 base-pair and a 265 base-pair product of the 16S rRNA gene. This method has a lower detection limit of 50 fg of DNA and six CFU of GBS per millilitre. Specificity was confirmed by analysing a range of Gram-positive and Gram-negative organisms and pediatric isolates. Polymerase chain reaction analysis of 56 cerebrospinal fluid specimens from infants under 1 year of age was performed and compared with culture. False-negative results were only encountered when processed CSF supernatant was analysed. False-positive results were obtained when DNA from Streptococcus porcinus was amplified, however this is a rare organism which has yet to be isolated as a cause of neonatal meningitis. The data indicate that semi-nested PCR is a rapid tool which might be used to confirm a diagnosis of GBS meningitis in infants and newborn babies.

Animals↗

Successful treatment of four patients with recalcitrant vaginal trichomoniasis with a combination of zinc sulfate douche and metronidazole therapy.

BACKGROUND AND OBJECTIVES: There is no certain cure available for patients suffering from recalcitrant trichomoniasis. Zinc sulfate is reported to have antitrichomonal properties. We report our experience in treating four patients empirically with a combination of zinc sulfate douche and metronidazole. STUDY DESIGN: A retrospective case analysis. Patients who presented to the tertiary referral clinic with chronic recurrent trichomoniasis without evidence of reinfection were treated empirically with a combination of zinc sulfate douching (1%) followed by a metronidazole 500 mg suppository per vaginale twice daily and 200 to 400 mg three times a day orally. The douching and suppository were used prophylactically for 3 nights after menstruation for some months. RESULTS: Four patients who had a history of 4 months to 4 years of culture-positive symptomatic trichomoniasis and received a variety of therapies before referral were treated successfully. At the review of 2 to 5 months after therapy, all had remained asymptomatic and the results of clinical and laboratory examinations were normal. CONCLUSIONS: The exact role of zinc sulfate douching in the successful outcome is not certain, but the combination therapy requires only a moderate dose of metronidazole (1.6-2.2 g/day), avoiding the side effects of larger doses. The combination therapy therefore merits further evaluation.

Adult↗

Pyrolysis mass spectrometry of cephalosporin-resistant Enterobacter cloacae.

Thirteen clinical and four environmental isolates of third-generation cephalosporin-resistant Enterobacter cloacae (CREC) together with single isolates from the hands of a nurse and from a blood gas analyser were associated with two clusters of nosocomial infection. With an unrelated CREC isolate they had been typed by serotype, biotype, ribotype and phage-type and were examined by pyrolysis mass spectrometry (PYMS) as described here. PYMS data yielded two clusters, major and minor. All except one isolate in the major cluster corresponded to type group identity (serotype 07, biotype 62, ribotype D) which had caused neonatal sepsis and colonization. Multivariate analysis showed a homogeneous group consisting of this strain plus two outliers. The minor cluster included four different strains, one of which, serotype 03, biotype 62, ribotype C had caused excoriation of the buttocks and colonization.

Cephalosporin Resistance↗

Species identification of members of the Streptococcus milleri group isolated from the vagina by ID 32 Strep system and differential phenotypic characteristics.

The importance of bacterial vaginosis as a risk factor in obstetric and gynecological infections has recently been recognized. The bacterial vaginosis group of organisms includes members of the Streptococcus milleri group, the identification of which has caused much confusion. We prospectively surveyed the rates of carriage of S. milleri group organisms in 397 high vaginal swabs received in our laboratory. For the identification of 99 clinical isolates and 23 control strains, we compared the results obtained by the rapid ID 32 Strep system (Analytab Products) and by a scheme utilizing six differential phenotypic characteristics (presence of beta-N-acetylglucosaminidase, alpha-glucosidase, beta-D-fucosidase, beta-galactosidase, beta-N-acetylgalactosaminidase, and beta-glucosidase) as described by Whiley et al. (R. A. Whiley, H. Fraser, J. M. Hardie, and D. Beighton, J. Clin. Microbiol. 28:1497-1501, 1990). We identified Streptococcus anginosus in 18% and Streptococcus constellatus in 0.05% of the specimens examined. Of the isolates of S. anginosus that reacted with grouping antisera, 20 of 25 belonged to Lancefield group F. The incubation conditions for bacterial cultures and for reaction mixtures affected the results of phenotypic characterization in the production of alpha-glucosidase, beta-galactosidase, and beta-glucosidase. However, by using bacterial cultures grown under hypercapnic conditions and incubating the reaction mixtures aerobically, consistent phenotypic characteristics were obtained, allowing identification similar to that obtained by the ID 32 Strep system. We therefore recommend the phenotypic scheme as an inexpensive, reliable, and convenient method for the initial identification of species of the S. milleri group.

Antibodies, Bacterial↗

Enterobacter cloacae in a neonatal intensive care unit: account of an outbreak and its relationship to use of third generation cephalosporins.

After uneventful use of cefotaxime and ceftazidime as first line therapy for three years in our neonatal intensive care unit we isolated cephalosporin-resistant Enterobacter cloacae (CREC) strains which caused clusters of cases or colonization and/or serious neonatal infection. By using two or more typing methods, at least five different strains with similar patterns of antimicrobial sensitivities were identified. The results of a case-control study did not support the notion that the use of third generation cephalosporins was associated with colonization and infection by CREC. The outbreak was brought under control by interrupting the transmission of the epidemic strain D, by measures such as cohort nursing, diligent handwashing before and after procedures, and thorough environmental cleaning as well as by decontamination with glutaraldehyde after dismantling of the blood gas analyser believed to have acted as a persistent reservoir. Our experience highlights the danger of inadequate supervision and maintenance of equipment used for near-patient testing and the need to monitor such equipment not only in terms of its calibration and analytical performance but also microbiologically.

Blood Gas Analysis↗

Hospital green salads and the effects of washing them.

Each week from April 1989 to February 1990, a plate of green salad prepared in the hospital kitchen was examined microbiologically. Of the 256 plates examined, 51% had total viable counts (TVCs) of greater than or equal to 10(5) colony forming units (cfu) g-1. Staphylococcus aureus was present in 13 samples and Escherichia coli in one sample. No Listeria monocytogenes, Clostridium perfringens or Salmonella spp. were isolated. The effect of washing mustard and cress, cucumber and the different layers of lettuce leaves was examined. Washing the salad by agitating it under running tap water in a colander for 2 min reduced the total bacterial counts by 10-fold. The inner leaves of a lettuce had TVCs less than 10(4)cfu g-1, at least 10-100-fold less than the outer leaves. Cucumber after washing had similar TVCs as after peeling. Five of six samples of mustard and cress had TVCs of at least 10(6)cfu g-1 before washing. As a consequence, mustard and cress was no longer used in our salads.

Colony Count, Microbial↗

Intraoperative wound contamination during abdominal hysterectomy.

Qualitative bacterial culture of specimens taken from several operative sites during abdominal hysterectomy has not been of value in predicting postoperative infection. We have therefore studied the relationship between the magnitude of contamination and the likelihood of the development of postoperative infection, in the course of a trial comparing the efficacy of cefotetan with ampicillin-plus-metronidazole for chemoprophylaxis in 163 women undergoing abdominal hysterectomy. Forty women who did not receive chemoprophylaxis were also studied. From each patient, an intraoperative sample of pelvic fluid was obtained after closure of the vaginal vault and examined quantitatively for anaerobic, aerobic and microaerophilic bacteria. The incidence of postoperative infectious morbidity (wound infection and febrile morbidity) was correlated with bacterial counts. Analyses by step-up multiple logistic regressions were performed on all the variables and only the total and microaerophilic bacterial counts were significant. Of the 40 patients with total bacterial counts greater than or equal to 10(4) cfu ml-1, 42.5% developed postoperative infectious morbidity, compared with 12.6% of 135 of patients with counts of less than or equal to 10(3) cfu ml-1. The contaminating bacteria were similar to those of the vaginal and skin flora, with anaerobes occurring in 52.9% and microaerophiles in 63.9% of positive fluid samples. Thus, we have concluded that the magnitude of contamination during abdominal hysterectomy is an important determinant in the development of postoperative infectious morbidity.

Ampicillin↗

Comparison of two commercial kits for identifying and biotyping Haemophilus parainfluenzae.

The Minitek system and the more recently introduced Micro Scan HNID panels for the identification and biotyping of 98 V dependent Haemophilus isolates were compared. Identical results were obtained for 77 isolates. The discrepancy in the results of ornithine and urease was accounted for mainly by the mismatching of the identification by the two kits. When 13 isolates of H parainfluenzae with mismatched biotypes were re-examined, the results from Micro Scan correlated with 92% of those obtained by Christensen's urea broth and 100% by the ornithine test (Lab M); the corresponding figures for Minitek were 61% and 30%, respectively. Micro Scan was easy to handle on the bench and results were ready on the same day. These results suggest that further work is required to assess these two systems for the biotyping of H parainfluenzae.

Bacterial Typing Techniques↗

Comparison of genital and respiratory carriage of Haemophilus parainfluenzae in men.

In the first study, genital carriage of Haemophilus parainfluenzae was investigated in 103 women and 292 men attending a clinic for genitourinary medicine. In a second study, pairs of urethral and throat swabs were studied in 279 men. The vaginal carriage was 2%, urethral 12.4% and throat 13.3%. Biotype 2 was found to be a genital type and throat carriage of this biotype was significantly associated with its concomitant urethral carriage. Biotypes 1 and 3 were mainly found in the throat. Biotype 2 was significantly more likely to be resistant to ampicillin, tetracycline and sulphonamide but biotype 1 was significantly more likely to be resistant to trimethoprim.

Bacterial Typing Techniques↗

Bacteriological contamination during laparoscopy with dye injection.

Peritoneal contamination with bacteria during the laparoscopy and dye procedure was studied in 38 subfertile women by culturing samples of peritoneal fluid, aspirated before, and after, injection of dye solution. Bacteria were carried with the dye into a previously sterile peritoneal cavity in 34 women (90%). These vaginal organisms were present in low concentrations, not exceeding 10(5) organisms/ml. These findings explain the low incidence of acute salpingitis after tubal patency tests, but the selective use of antibiotic prophylaxis is recommended.

Coloring Agents↗

Intragastric acidity, bacteria, nitrite, and N-nitroso compounds before, during, and after cimetidine treatment.

Eight healthy subjects were studied half-hourly or hourly for 24 h periods before, during, and after cimetidine treatment. No significant differences in intragastric bacterial counts or bacterial species or in intragastric nitrite or N-nitroso-compound concentrations were found as a result of cimetidine treatment. Bacterial counts and nitrite concentrations tended to increase with pH, but N-nitroso-compound concentrations did not. This study provides no evidence that cimetidine treatment may increase the risk of gastric carcinoma by raising N-nitroso-compound concentrations.

Bacteria↗