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Biomedical subjects

A L Rashad

Publications and source records attributed to A L Rashad.

At least 19 recordsLinked to original sources
PubMed1993

Plasmid DNA analysis, biotyping, and antimicrobic susceptibility as subtyping tests for Klebsiella pneumoniae and Klebsiella oxytoca.

We compared plasmid DNA analysis, biotyping by Vitek, and disk diffusion antimicrobic susceptibility as subtyping tests of Klebsiella pneumoniae and Klebsiella oxytoca. The 92 tested isolates were from alternate, culture-positive patients over 6 months. No outbreak or cluster of infections was recognized during this interval. Plasmid DNA was detected in 85% of the isolates. Each isolate except one had a reproducible absence of plasmid DNA or a reproducible plasmid DNA profile on repetitive testing. Restriction endonuclease enzyme analysis of plasmid DNA was necessary to distinguish differences among some isolates that had only large plasmids. Isolates with only large plasmids represented 18% of the collection. Of the 78 isolates with plasmid DNA, all but two were considered different from one another by plasmid DNA analysis. Biotyping and antimicrobic susceptibility testing were not highly reproducible. In addition, biotyping did not demonstrate a sufficient variety of patterns among the isolates for subtyping purposes. We conclude that plasmid DNA analysis is very useful as a subtyping test for isolates of K. pneumoniae and K. oxytoca. Neither biotyping nor antimicrobial susceptibility as performed in our laboratory had sufficient discriminatory power and reproducibility for subtyping these organisms.

Anti-Bacterial Agents↗
PubMed1993

Comparison of the Septi-Chek AFB and BACTEC systems and conventional culture for recovery of mycobacteria.

The performance of the Septi-Chek AFB system was compared with that of the BACTEC radiometric system and that of Lowenstein-Jensen agar slants (LJ) for detection of mycobacteria in clinical specimens. A total of 642 specimens were cultured; 61 (9.5%) yielded mycobacteria. Mycobacterium tuberculosis (34 isolates) and Mycobacterium avium complex (25 isolates) were the predominant species isolated. Of the 61 culture-positive specimens, 30 were smear positive and 31 were smear negative. Overall, 95% of the positive specimens were detected by Septi-Chek and BACTEC (100% of M. tuberculosis isolates) and 75% by LJ (82% of M. tuberculosis isolates). The mean times to detection were 15 days for BACTEC, 23 days for Septi-Chek, and 27 days for LJ. Of the 30 smear-positive specimens, 100% were recovered by Septi-Chek and BACTEC and 90% were recovered by LJ. Of the 31 smear-negative specimens, 90% were detected by Septi-Chek and BACTEC and 61% were detected by LJ. The Septi-Chek and BACTEC systems are superior to the conventional (LJ) mycobacterial culture method. Although Septi-Chek requires more time for the detection of mycobacteria than BACTEC, it is comparable in terms of overall recovery.

Bacteriological Techniques↗
PubMed1992

Vaginal PO2 in healthy women and in women infected with Trichomonas vaginalis: potential implications for metronidazole therapy.

We measured the PO2, pH, and temperature in the vaginal canals of nine patients with symptomatic Trichomonas vaginitis and those of 10 healthy women. The patients included eight women with primary infections caused by metronidazole-susceptible strains and one refractory case that resulted from infection with a metronidazole-resistant Trichomonas vaginalis. The median vaginal PO2, pH, and temperature in the patient group were 1 mm Hg, 6, and 37.3 degrees C respectively; these medians were 1 mm Hg, less than or equal to 4.5, and 37.2 degrees C in the healthy group. These data show that vaginal environment is anaerobic or microaerophilic (it has reduced oxygen tension). Because the activity of metronidazole is reduced under aerobiosis, the vaginal environment should enhance the biologic activity of the drug.

Adult↗
PubMed1990

Plasmid DNA fingerprinting of Acinetobacter calcoaceticus subspecies anitratus from intubated and mechanically ventilated patients.

Forty-three intubated and mechanically ventilated patients in five intensive care units (ICUs) of one hospital developed respiratory colonization or infection with Acinetobacter calcoaceticus subspecies anitratus over a 16-month interval. Neither the frequency nor rate of A anitratus isolation exceeded the hospital endemic norms. Single isolates from 34 of the patients were subtyped by plasmid DNA analysis, two biotyping systems and antimicrobial susceptibility to 24 drugs. Plasmid DNA fingerprints were distinct in 18 isolates (they differed from each other and all others), similar in two and identical or similar in ten. The latter group of isolates were recovered from patients in four ICUs. Reproducibility of biotyping was poor. Neither biotyping nor antimicrobial susceptibility were successful in identifying sameness among the group isolates nor differences among other isolates. We conclude that plasmid DNA fingerprinting should be used to assess the possibility of multiple patient transmissions of the same A anitratus strain in the absence of an obvious outbreak.

Acinetobacter↗
PubMed1989

Restriction enzyme analysis of plasmid DNA and bacteriophage typing of paired Staphylococcus aureus blood culture isolates.

We compared restriction enzyme analysis of plasmid (REAP) DNA profiling with bacteriophage typing for determination of similarities and differences among 50 pairs of Staphylococcus aureus blood isolates from patients with multiple positive blood cultures. Isolates from 17 pairs did not have detectable plasmids. Isolates from 33 pairs had plasmids classified into 17 distinct REAP DNA profiles. Paired isolates from 31 of these episodes were identical to one another. By phage typing, 35 pairs had strong lytic reactions to a phage(s), 9 pairs lacked strong reactions, and 6 pairs consisted of a strongly reactive isolate and an isolate with no strong reaction to a phage. When consolidated into 11 general phage groups, pairs from 44 of the 50 episodes were in the same general group. REAP DNA profiles were highly reproducible (99%), whereas phage typing was not. REAP DNA profiling is superior to phage typing as a technique for determining similarities and differences among S. aureus blood isolates.

Bacteriophage Typing↗
PubMed1988

Multiple intensive care unit outbreak of Acinetobacter calcoaceticus subspecies anitratus respiratory infection and colonization associated with contaminated, reusable ventilator circuits and resuscitation bags.

PURPOSE: Acinetobacter calcoaceticus subspecies anitratus (A. anitratus) can cause nosocomially and community acquired pneumonia. Source identification of the organism is often difficult. An outbreak of respiratory infection and colonization with A. anitratus affecting 93 ventilated patients in all six of a hospital's intensive care units (ICUs) over 10 months is described. PATIENTS AND METHODS: In April 1984, the infection control staff started to review positive culture results from all patients in all ICUs. At this point, information on significant isolates was recorded by patient, site, date, genus and species, and antimicrobial susceptibility. During the month of August 1984, an increased number of A. anitratus isolates from sputum began to be detected. Information was expanded to include the date of hospital admission, ICU admission, intubation, and extubation; the dates and types of all surgical procedures; the results and dates of all prior sputum cultures; and the use of nebulized bronchodilator medications. Monthly numbers of cases were compared for four months prior to the outbreak, during the outbreak, and for seven months after the outbreak. Plasmid DNA from isolates was prepared, electrophoresed, and visualized. Isolates were designated according to the molecular weights of visualized plasmids. RESULTS: Barrier precautions and improved staff handwashing did not diminish the frequency of new cases. When pasteurized, reusable ventilator circuits and resuscitation bags were cultured for the possibility of low-level contamination, 18 percent were positive for A. anitratus. Terminal ethylene oxide sterilization of these devices was associated with prompt control of the outbreak. Plasmid DNA analysis of isolates from patients involved in the outbreak, contaminated devices, and the hands of personnel responsible for device disinfection revealed two predominant plasmid profiles. After outbreak control, isolates with these profiles were found much less frequently in patient specimens. CONCLUSION: Contaminated, reusable ventilator support equipment may be a leading cause for the extent of A. anitratus in the sputum of intubated patients. This problem is potentially correctable by the use of terminal etyhlene oxide sterilization of reusable ventilator circuits and resuscitation bags.

Acinetobacter↗
PubMed1988

Ciprofloxacin activity in cyst fluid from polycystic kidneys.

Renal cyst infection in patients with polycystic kidney disease (PKD) is often unresponsive to standard antimicrobial therapy, in part because of the failure of most antibiotics to adequately penetrate cyst fluid. Ciprofloxacin, a new quinolone antibiotic, possesses in vitro activity against most pathogens likely to be encountered in renal cyst infection. To study the potential usefulness of ciprofloxacin for the treatment of cyst infection, fluid from 70 cysts was obtained from seven patients with polycystic kidney disease who were receiving the drug. Cysts were categorized as nongradient or gradient by the sodium concentration in the fluid. The ciprofloxacin concentration within cysts was measured, and the cyst fluid bactericidal activity against likely cyst fluid pathogens was determined. The mean (+/- standard error) ciprofloxacin concentration was 12.7 +/- 2.9 micrograms/ml. Preferential accumulation of ciprofloxacin occurred in gradient cysts; these levels exceeded levels in serum by more than fourfold. Cyst fluid bactericidal activity titers were uniformly high against Escherichia coli and Proteus mirabilis, while less activity was observed against Streptococcus faecalis, Pseudomonas aeruginosa, Staphylococcus aureus, and Staphylococcus epidermidis.

Adult↗
PubMed1988

A technique for removal of filariasis of the anterior chamber.

We describe a useful technique for removing filaria from the anterior chamber. In the case described, an immature female filaria approximately 15 mm in length was removed from the anterior chamber of a 32-year-old man in western Oregon and identified as a species of Dipetalonema. Features of four cases of filarial infection in the anterior chamber from the same geographic area are described. In three out of four cases, the worms were removed alive without difficulty by means of simple irrigation aspiration system.

Adult↗
PubMed1987

Trimethoprim-sulfamethoxazole in cyst fluid from autosomal dominant polycystic kidneys.

Cyst infection in patients with autosomal-dominant polycystic kidney disease (ADPKD) is often refractory to therapy, in part because of the limited entry of commonly used antibiotics into cyst fluid. To study the efficacy of trimethoprim-sulfamethoxazole in cyst infection, cyst fluid was obtained by percutaneous aspiration or at surgery from eight patients with ADPKD receiving trimethoprim-sulfamethoxazole. Cysts were categorized as nongradient or gradient by cyst-fluid sodium concentration. Trimethoprim-sulfamethoxazole concentrations within cysts were determined and cyst fluid inhibitory and bactericidal titers were assessed in vitro against Escherichia coli, Proteus mirabilis and Streptococcus fecalis. The mean cyst fluid trimethoprim and sulfamethoxazole concentrations were 15.2 micrograms/ml and 42.5 micrograms/ml, respectively. Preferential accumulation of trimethoprim was observed in gradient cysts, exceeding serum levels more than eightfold. Sulfamethoxazole penetrated cysts to a lesser extent, with concentrations ranging from 10 to 70 percent of the serum level. Cyst fluid sampled prior to trimethoprim-sulfamethoxazole administration (control) demonstrated no antibacterial activity, while cyst fluid inhibitory and bactericidal titers following antibiotic administration were 1:32 or greater in most instances. These studies indicate that trimethoprim-sulfamethoxazole is likely to be efficacious in the treatment of cyst infection in polycystic kidneys.

Adult↗
PubMed1985

Cyst fluid antibiotic concentrations in autosomal-dominant polycystic kidney disease.

Infections involving cysts of patients with autosomal-dominant polycystic kidney disease (PCKD) are often refractory to therapy possibly because of poor penetration of antibiotics into cyst fluid. Ten patients with PCKD had blood urine and cyst fluid sampled at surgery or autopsy for antibiotic concentrations. Cysts were categorized as to their nephron site of origin by cyst fluid sodium concentrations. Drugs active against anaerobes such as metronidazole and clindamycin were present in therapeutic concentrations in both proximal and distal cysts. Ampicillin and trimethoprim-sulfamethoxazole had the best profiles considering likely infecting organisms and the antibiotic concentrations achieved in both type of cysts. It is likely that prolonged therapy with both of these drugs is necessary to insure therapeutic success. Other drugs that can be detected in cysts are lipid soluble, undergo tubular secretion, or have high pKa values. These include erythromycin, vancomycin, and cefotaxime. Aminoglycosides because of their predominant glomerular filtration and thus low filtration rate per single cystic nephron are undetectable in both proximal and distal cysts. Clinically, alternatives to aminoglycosides should be chosen for infected cysts in PCKD.

Adult↗
PubMed1981

Evaluation of a direct blood culture disk diffusion antimicrobial susceptibility test.

A total of 556 unique blood culture isolates of nonfastidious aerobic and facultatively anaerobic bacteria were examined by direct and standardized disk susceptibility test methods (4,234 antibiotic-organism comparisons). When discrepancies which could be accounted for by the variability inherent in disk diffusion susceptibility tests were excluded, the direct method demonstrated 96.8% overall agreement with the standardized method. A total of 1.6% minor, 1.5% major, and 0.1% very major discrepancies were noted.

Bacteria↗
PubMed1980

beta-Lactamase activity in human pus.

Pus was obtained from patients with polymicrobial intraabdominal abscesses or polymicrobial empyema. Physical and chemical characteristics of 12 specimens were examined, and bacterial isolates were enumerated. Pus supernatant of six specimens rapidly inactivated penicillin, cephalothin, and cefazolin. Carbenicillin and ticarcillin were similarly degraded by supernatant of certain pus specimens. Cefoxitin, chloramphenicol, and clindamycin were not appreciably inactivated by pus supernatant. Degradation of penicillin and cephalosporin congeners in pus was due to the presence of beta-lactamase, as shown by chemical interaction with nitrocefin, chromatography, and inhibition by the beta-lactamase inhibitor clavulanic acid. Pus supernatant containing beta-lactamase activity reduced the bactericidal activity of carbenicillin against Bacteroides fragilis in whole pus in an abscess model in vitro. Bactericidal activity of clindamycin or cefoxitin was not impaired in pus containing beta-lactamase.

Bacteroides fragilis↗