Diverse Escherichia coli pathovars of phylogroups B2 and D isolated from animals in Tunisia

Introduction: The virulent Escherichia coli strains responsible for extraintestinal infections were mainly belonged to B2 and D phylogroups. However, no past studies have determinate via the presence of virulence genes the frequency of E. coli pathovars recovered from animals housed in farms in Tunisia. The aims of this study were to investigate 26 E. coli isolated from healthy and diarrheic animals and to determinate via the presence of virulence genes the frequency of pathovars. Methodology: Twenty-six E. coli isolates of phylogroups B2 (n = 14), B22 (n = 9), B23 (n = 5), and D2 (n = 12) were characterized. Genes encoding virulence factors (fimH,eaeA,aggC,papC, papG allele III, hlyA, east1, cnf1, exhA,stx1, stx2, iutA, fyuA, ibeA,and ipaH), and antibiotic resistance as well as class 1 and 2 integrons were searched by polymerase chain reaction (PCR). The genetic relationship of isolates was done by PFGE. Results: According to the occurrence of specific genes the 26 isolates were classified as:9 EAEC, 2 EHEC, 4 UPEC, 3 EPEC/EHEC and 1 NTEC. Therefore, 2 Ex-PEC and 5 APEC were presented amongst our strains. Some isolates (12) were clonal and the remaining was unrelated. Conclusions: Higher diversity of pathovars which carried diverse combinations of virulence genes in healthy isolates. In addition, it seems that the infections were caused by different mechanisms.

Occurrence of bla CTX-M-1, qnrB1 and virulence genes in avian ESBL-producing Escherichia coli isolates from Tunisia

Avian ESBL-producing Escherichia coli isolates have been increasingly reported worldwide. Animal to human dissemination, via food chain or direct contact, of these resistant bacteria has been reported. In Tunisia, little is known about avian ESBL- producing E. coli and further studies are needed. Seventeen ESBL-producing Escherichia coli isolates from poultry feces from two farms (Farm 1 and farm 2) in the North of Tunisia have been used in this study. Eleven of these isolates (from farm 1) have the same resistance profile to nalidixic acid, sulfonamides, streptomycin, tetracycline, and norfloxacine (intermediately resistant). Out of the six isolates recovered from farm 2, only one was co-resistant to tetracycline. All isolates, except one, harbored bla_CTX-M-1 gene, and one strain co-harbored the bla_TEM-1 gene. The genes tetA and tetB were carried, respectively, by 11 and 1 amongst the 12 tetracycline-resistant isolates. Sulfonamides resistance was encoded by sul1, sul2, and sul3 genes in 3, 17, and 5 isolates, respectively. The qnrB1 was detected in nine strains, one of which co-harbored qnrS1 gene. The search for the class 1 and 2 integrons by PCR showed that in farm 1, class 1 and 2 integrons were found in one and ten isolates, respectively. In farm 2, class 1 integron was found in only one isolate, class 2 was not detected. Only one gene cassette arrangement was demonstrated in the variable regions (VR) of the 10 int2-positive isolates: dfrA1- sat2-aadA1. The size of the VR of the class 1 integron was approximately 250 bp in one int1-positive isolate, whereas in the second isolate, no amplification was observed. All isolates of farm 1 belong to the phylogroup A (sub-group A0). However, different types of phylogroups in farm 2 were detected. Each of the phylogroups A1, B2₂, B2₃ was detected in one strain, while the D2 phylogroup was found in 3 isolates. The virulence genes iutA, fimH, and traT were detected in 3, 7, and 3 isolates, respectively. Two types of gene combination were detected: iutA+fimH+traT in 3 isolates and iutA+fimH in one isolate. The isolates recovered in farm 1 showed the same profile of PFGE macro-restriction, while isolates of farm 2 presented unrelated PFGE patterns. We conclude that these avian ESBL-producing E. coli isolates show homo- and heterogenic genetic background and that plasmids harboring ESBL genes could be involved in the dissemination of this resistance phenotype.

Effect of thioridazine on phenytoin serum concentration: a retrospective study

Serum phenytoin concentrations before and after the addition of thioridazine were retrospectively compared in 27 adults to determine if an interaction occurred between these two drugs. A change in the serum phenytoin concentration of +/- 4 micrograms/ml was considered clinically significant; by this definition four patients (14.8 percent) had an increase, two (7.4 percent) had a decrease, and most (77.8 percent) demonstrated no change. The mean difference was 0.8 microgram/ml +/- 3.7 micrograms/ml and was not found to be statistically significant (p less than 0.1). Clinically important alterations in phenytoin serum concentration as caused by thioridazine appear to be infrequent.

Comparison of eight phenytoin dosing methods in institutionalized patients

Until now, no evaluation of phenytoin dosing methods has been undertaken in a large group of patients, to our knowledge. The goal of this study was to determine which of eight different dosing methods most accurately predicts a phenytoin steady-state concentration. Seventy-six patients were chosen, retrospectively, from a state-funded institution for the mentally retarded. Eligibility criteria included two or more different doses of phenytoin and corresponding plasma concentrations. Relative predictive performance was determined by comparing results of simple linear regression. Also, relative bias and precision were determined by comparing mean prediction errors, root mean squared errors, and respective 95% confidence intervals. Of the methods requiring one dose-concentration pair, Rambeck's nomogram was the best predictor of phenytoin concentrations. The methods requiring two known doses and plasma concentrations were more accurate. Their predictive performance was equivalent, although use of the Tozer equation might be preferred for its convenience. None of the methods tested were sufficiently precise to substitute for confirmatory serum phenytoin concentrations.

Drug-related admissions to a Veterans' Administration psychiatric unit

Forty-one consecutive admissions to an inpatient psychiatric service were monitored prospectively for drug-related problems. During the four-month study, 22 (54 percent) of the admissions were determined to be drug-related; in 12 (29 percent) admissions, a drug-related problem was identified as the primary cause of hospitalization. Significant differences were found in the length of hospitalization, age, and race when the group with drug-related problems was compared with a group with non-drug-related problems.

Effect of cimetidine on phenytoin serum levels

Cimetidine, 300 mg p.o. four times a day, was administered for 5 days to nine epileptics who were stabilized while receiving phenytoin. Five patients had statistically significant increases in phenytoin serum levels, including two who became clinically toxic. One patient had a statistically significant decrease in phenytoin serum concentration. A relationship was not found between cimetidine levels and change in phenytoin serum levels. Cimetidine can cause significant changes in phenytoin serum levels which may be manifested clinically.

Recommendations for monitoring lithium therapy

The literature concerning side effects of normal serum levels of lithium on various organ systems is reviewed. Suggestions for monitoring and managing these adverse effects are discussed. A table is presented that provides recommendations for evaluation prior to initiation and during follow-up of therapy.

Rapid infusion of phenytoin sodium loading doses

The use of rapid intravenous infusions of phenytoin sodium to achieve prompt plasma therapeutic concentrations of phenytoin was studied in adult epileptic patients. Six adult patients who experienced recent tonic-clonic seizures were selected for study. Four of them had not been treated with phenytoin before the study; two were on chronic phenytoin therapy but had subtherapeutic serum levels. A leading dose of phenytoin sodium (15 mg/kg in 100 ml of 0.9% sodium chloride injection) was infused at 30-50 mg/min. Blood samples were drawn before phenytoin administration, every five minutes during the infusion, and at 1, 2, 4, 8, 12, 18, and 24 hours after completion of the infusion. Adverse effects were monitored during the infusion. Pharmacokinetic variables were calculated. Patients received from 750 to 1500 mg phenytoin sodium (mean +/- S.D. = 1040.8 +/- 297.3 mg). From 5 to 30 minutes were required to reach therapeutic (10-20 micrograms/ml) serum phenytoin concentrations; concentrations peaked at 31.1 +/- 10.0 micrograms/ml. Four of the six patients had therapeutic serum concentrations at 18 hours after completion of the infusion. Adverse effects were minimal and not severe; no cardiotoxicities were noted. Phenytoin half-life was 31.2 +/- 8.4 hours, total plasma clearance was 47.2 +/- 10.7 ml/kg/hr, and volume of distribution was 1.96 +/- 0.46 liters/kg. It is concluded that rapid intravenous infusion of phenytoin appears to be a reasonably safe and effective method of rapidly reaching therapeutic phenytoin concentrations.

Parenteral nutrition utilization: evaluation of an educational protocol and consult service

A two part study was undertaken to evaluate the effectiveness of an educational protocol and consult service on parenteral nutrition (PN) utilization. Forty-one patient admissions were evaluated retrospectively and nine prospectively. Average length of hospital stay and number of days on PN were decreased significantly (p less than .05). Frequency of adverse effects were also decreased significantly (p less than .05). A positive trend toward selection of patients for enteral rather than PN was evidenced. Utilization of already available manpower and financial resources by this modified approach should contribute toward reducing costs and hazards of PN therapy, particularly for smaller hospitals with both limited requirements and resources, as well as for teaching institutions.