The empirical use of aminoglycosides in Ludwig's angina based on bacterial analysis of 63 cases

PURPOSES

To determine if the empirical use of aminoglycosides is justified in Ludwig's angina based on microscopy, culture and sensitivity results.

METHODS

A retrospective analysis was done on patients that presented with Ludwig's angina to the Maxillofacial and Oral surgery department at the University of Pretoria. Demographical data was extracted from patient files. Pus specimens that were submitted as part of the initial surgical intervention were analysed.

RESULTS

Sixty-three patients were included in the study with the majority, 76.19% (n=48/63), comprising males. The mean patient age was 38.6 years (range 6 months to 78 years). The majority of infections (87.3%) had an odontogenic aetiology (n=55/63). Forty-four percent of the patients had immunosuppressive co-morbidities (n=28/63). Streptococci contributed 71.26% (n=62/87) of the cultured bacteria. Similar bacteria were cultured in the immunocompromised and the immunocompetent patients (p=0.672). Ninety-two percent (n=57/62) of the streptococci cultured were sensitive to penicillin. The addition of aminoglycosides to the study sample would not have made a statistically significant difference (p=0.1556).

CONCLUSION

Based on the findings of this study, the empirical use of aminoglycosides is not warranted in either immunocompromised or immunocompetent patients with Ludwig's angina.

A case report of Nocardia asiatica constrictive pericarditis in a patient with Human Immunodeficiency Virus

Nocardiosis commonly affects the respiratory system and is a rare cause of purulent pericarditis. Invasive nocardial infections occur more frequently in patients with immunosuppression. A misdiagnosis as tuberculosis infection is not uncommon, especially in the context of immunosuppression in high burden tuberculosis settings. The risk factors and clinical features of the two disease entities overlap substantially. Misdiagnosis may lead to a delay in appropriate treatment and may result in poor outcomes. It is important to note that these conditions may also co-exist in the same patient. We describe, to the best of our knowledge, the first case of Nocardia asiatica pericarditis in a 32-year-old man with Human Immunodeficiency Virus infection. The patient was initially diagnosed in September 2020 with a lower respiratory tract infection and pulmonary tuberculosis was suspected. A chest radiograph, performed at admission, revealed a pericardial effusion and N. asiatica was cultured from a pericardial fluid specimen that was collected 5 days following admission. Despite a good initial clinical response to a combination of trimethoprim/sulfamethoxazole and imipenem/cilastatin, the patient demised after 16 weeks of treatment. Previous reports of laboratory confirmed nocardial pericarditis are also reviewed and summarized.

Development, evaluation and validation of machine learning algorithms to detect atypical and asymptomatic presentations of Covid-19 in hospital practice

BACKGROUND

Diagnostic methods for Covid-19 have improved, both in speed and availability. Because of atypical and asymptomatic carriage of the virus and nosocomial spread within institutions, timely diagnosis remains a challenge. Machine learning models trained on blood test results have shown promise in identifying cases of Covid-19.

AIMS

To train and validate a machine learning model capable of differentiating Covid-19 positive from negative patients using routine blood tests and assess the model's accuracy against atypical and asymptomatic presentations.

DESIGN AND METHODS

We conducted a retrospective analysis of medical admissions to our institution during March and April 2020. Participants were categorized into Covid-19 positive or negative groups based on clinical, radiological features or nasopharyngeal swab. A machine learning model was trained on laboratory parameters and validated for accuracy, sensitivity and specificity and externally validated at an unconnected establishment.

RESULTS

An Ensemble Bagged Tree model was trained on data collected from 405 patients (212 Covid-19 positive) producing an accuracy of 81.79% (95% confidence interval (CI) 77.53-85.55%), the sensitivity of 85.85% (CI 80.42-90.24%) and specificity of 76.65% (CI 69.49-82.84%). Accuracy was preserved for atypical and asymptomatic subgroups. Using an external data set for 226 patients (141 Covid-19 positive) accuracy of 76.82% (CI 70.87-82.08%), sensitivity of 78.38% (CI 70.87-84.72%) and specificity of 74.12% (CI 63.48-83.01%) was achieved.

CONCLUSION

A machine learning model using routine laboratory parameters can detect atypical and asymptomatic presentations of Covid-19 and might be an adjunct to existing screening measures.

Diagnostic accuracy of the BioFire FilmArray blood culture identification panel when used in critically ill patients with sepsis

Sepsis accounts for high mortality rates in critical care units. Prompt and accurate identification of causative pathogens and initiation of appropriate antimicrobial therapy is critical for the appropriate management of patients in order to optimise clinical outcomes. The BioFire FilmArray blood culture identification (BCID) panel is a US Food and Drug Administration (FDA) approved rapid, multiplex polymerase chain reaction (PCR) assay that is able to identify a variety of bacteria, fungi and antimicrobial resistance determinants directly from positive blood cultures. The aim of this study was to evaluate the diagnostic performance of the BioFire FilmArray BCID panel against the gold standard of blood cultures. Seventy-eight positive blood cultures obtained from critically ill patients suspected of having sepsis were included in the study. Each bottle was processed with the BioFire FilmArray BCID panel as well as conventional culture methods. Diagnostic accuracy of the BioFire FilmArray BCID panel was determined. The assay demonstrated a high sensitivity and specificity for pathogen identification of 96.5% (95% CI, 91.3-99.0) and 99.7% (95% CI, 99.3-99.9), respectively. The findings of this study support the role of the BioFire FilmArray BCID panel in the management of critically ill patients with sepsis.

Clinical utility of the BioFire FilmArray Blood Culture Identification panel in the adjustment of empiric antimicrobial therapy in the critically ill septic patient

Sepsis and septic shock are key contributors to mortality in critically ill patients and thus prompt recognition and management thereof is central to achieving improved patient outcomes. Early initiation of appropriate antimicrobial therapy constitutes a crucial component of the management strategy and thus early identification of the causative pathogen is essential in informing antimicrobial therapeutic choices. The BioFire FilmArray blood culture identification (BCID) panel is a US Food and Drug Administration (FDA) approved rapid, multiplex polymerase chain reaction assay for use on positive blood cultures. This study evaluated its clinical utility in the intensive care unit (ICU) setting, in terms of amendment of empiric antimicrobial therapy in critically ill patients with sepsis. The assay proved useful in this setting as final results were made available to clinicians significantly earlier than with conventional culture methods. This, in turn, allowed for modification of empirical antimicrobial therapy to more appropriate agents in 32% of patients. Additionally, the use of the BioFire FilmArray BCID panel permitted the prompt implementation of additional infection prevention and control practices in a sizeable proportion (14%) of patients in the study who were harbouring multidrug resistant pathogens. These findings support the use of the BioFire FilmArray BCID panel as a valuable adjunct to conventional culture methods for the diagnosis and subsequent management of critically ill patients with sepsis.

Laboratory evaluation of the BioFire FilmArray Pneumonia plus panel compared to conventional methods for the identification of bacteria in lower respiratory tract specimens: a prospective cross-sectional study from South Africa

Lower respiratory tract infections are important causes of morbidity and mortality. The global increase in antimicrobial resistance necessitates rapid diagnostic assays. The BioFire FilmArray Pneumonia plus (FAPP) panel is a Food and Drug Administration-approved multiplex polymerase chain reaction assay that detects the most important etiological agents of pneumonia and associated antibiotic resistance genes, in approximately 1 hour. This study assessed the diagnostic performance of this assay by comparing it to conventional culture methods in the analysis of 59 lower respiratory tract specimens. The sensitivity and specificity of the FAPP panel for bacterial detection were 92.0% (95% confidence interval [CI], 80.8% to 97.8%) and 93.8% (95% CI, 91.1% to 95.3%) respectively. For detecting antibiotic resistance, the positive- and negative percent agreement were 100% (95% CI, 81.5% to 100.0%) and 98.5% (95% CI, 216 96.7% to 99.4%) respectively. The FAPP panel was found to be highly accurate in evaluating tracheal aspirate specimens from hospitalized patients.

Post-procedural Bacillus cereus septic arthritis in a patient with systemic lupus erythematosus

INTRODUCTION

Bacillus species are often considered as contaminants when cultured from clinical samples. Bacillus cereus may be a pathogen in certain circumstances and is known to cause musculoskeletal infections. This report aims to educate clinicians and clinical microbiology laboratories on B. cereus musculoskeletal infections and to heighten awareness that Bacillus species should not always be dismissed as contaminants.

CASE PRESENTATION

We report the case of a patient who presented to a tertiary hospital in Pretoria, South Africa, in November 2018 with B. cereus septic arthritis and underlying systemic lupus erythematosus (SLE). The isolate would otherwise have been dismissed as a contaminant had it not been for the crucial interaction between the laboratory and the treating clinicians. To our knowledge, this is the first case report of septic arthritis caused by B. cereus in an SLE patient where the organism was cultured from the joint specimen. Identification of the organism was performed using matrix-assisted laser desorption/ionisation mass spectrometry.

MANAGEMENT AND OUTCOME

Definitive treatment was with intravenous vancomycin, continued for four weeks, in addition to arthroscopy and management of the underlying SLE. The patient had a good clinical outcome and regained full mobility.

CONCLUSION

Musculoskeletal infections, specifically septic arthritis caused by B. cereus, are exceedingly rare infections. Immune suppression, trauma, prosthetic implants and invasive procedures are important risk factors for B. cereus musculoskeletal infections. Close collaboration with a multi-disciplinary team approach will effect the best outcome for complicated patients with B. cereus infections.

Genome sequence of a clinical Salmonella Enteritidis sequence type 11 strain from South Africa

OBJECTIVES

The underlying resistance mechanism and phylogenetic relationship of a colistin-resistant Salmonella enterica serovar Enteritidis strain EC20120916 that resulted in fatal meningitis in an immunocompromised patient was investigated by whole-genome sequencing (WGS) analysis.

METHODS

WGS of strain EC20120916 was performed on an Illumina MiSeq platform and annotation of the sequence was performed using the Prokaryotic Genome Annotation Pipeline (PGAP). Antimicrobial resistance genes, plasmid replicons and pathogenicity islands were identified. A phylogenetic tree was constructed using Parsnp and was edited with FigTree.

RESULTS

The genome size of strain EC20120916 is 4 699 318 bp with a GC content of 55.2% and 4471 protein-coding genes. The aac(6')-laa gene, encoding resistance to aminoglycosides, was identified although this was not expressed phenotypically in the isolate. No colistin resistance-conferring mutations or plasmid-mediated mechanisms were identified to explain the colistin resistance. The strain was phylogenetically related to three international strains, although it was not close enough to suggest importation from outside of South Africa.

CONCLUSION

This is the first report of a colistin-resistant Salmonella Enteritidis isolate causing meningitis in an immunocompromised patient in South Africa. The absence of colistin resistance-conferring mutations or plasmid-mediated resistance mechanisms suggest that a novel mechanism is responsible for the colistin resistance in this isolate. The isolate was acquired locally.

A rare case of Colistin-resistant Salmonella Enteritidis meningitis in an HIV-seropositive patient

Background

Non-typhoidal salmonellae (NTS) have been associated with invasive disease, notably meningitis, in immunocompromised individuals. Infections of this nature carry high rates of morbidity and mortality. Colistin resistance in salmonellae is a rare finding, more so in an invasive isolate such as cerebrospinal fluid (CSF). Colistin resistance has important infection control implications and failure to manage this phenomenon may lead to the loss of our last line of defence against multi-drug resistant Gram-negative organisms. To our knowledge, this is the first reported clinical case of colistin-resistant Salmonella Enteritidis meningitis in South Africa.

Case presentation

We report a case of a young male patient with advanced human immunodeficiency virus (HIV) infection who presented to hospital with symptoms of meningitis. Cerebrospinal fluid (CSF) cultured a Salmonella Enteritidis strain. Antimicrobial susceptibility testing (AST) of the isolate, revealed the strain to be colistin resistant. Despite early and aggressive antimicrobial therapy, the patient succumbed to the illness after a short stay in hospital. Subsequent genomic analysis of the isolate showed no presence of the mcr genes or resistance-conferring mutations in phoPQ, pmrAB, pmrHFIJKLME/arnBCADTEF, mgrB, and acrAB genes, suggesting the presence of a novel colistin resistance mechanism.

Conclusion

Invasive non-typhoidal salmonellae infection should be suspected in patients with advanced immunosuppression who present with clinical features of meningitis. Despite early and appropriate empiric therapy, these infections are commonly associated with adverse outcomes to the patient. Combination therapy with two active anti-Salmonella agents may be a consideration in the future to overcome the high mortality associated with NTS meningitis. Colistin resistance in clinical Salmonella isolates, although a rare finding at present, has significant public health and infection control implications. The causative mechanism of resistance should be sought in all cases.

Electronic supplementary material

The online version of this article (10.1186/s12879-019-4391-7) contains supplementary material, which is available to authorized users.

Pharmacokinetics of ceftazidime administered to lactating and non-lactating goats

The aim of this work was to determine the pharmacokinetics of intravenous (iv) and intramuscular (im) ceftazidime administered to lactating (LTG; n = 6) and non-lactating (NLTG; n=6) healthy Creole goats in 2 trials (T1 and T2). During T1 and T2, goats randomly received a single dose of im or iv ceftazidime (10 mg/kg). Serum concentration of iv ceftazidime in NLTG and LTG goats is best described by 2 and 3 compartment models, respectively. The pharmacokinetic parameters of iv and im ceftazidime administered to LTG and NLTG showed statistically significant differences (P0.05) in the constants (λz, T1 vs T2 [iv] 0.5±0.1 vs 0.3±0.1 /h; T1 vs T2 [im] 0.5±0.2 vs 0.3±0.1 /h) and in the mean times (t1/2, T 1 vs T 2 [iv] 1.6±0.3 vs 2.3±0.6 h; T 1 vs T 2 [im] 1.6±0.7 vs 2.6±0.9 h) of elimination. The bioavailability of ceftazidime in LTG and NLTG was 113.0 ± 17.8 and 96.0 ± 18.0 %, respectively. Ceftazidime concentration in milk at 2 h was: iv = 1.9 ± 0.2 and im = 2.4 ± 0.5 μg/m ; the penetration in milk was iv = 18.3 ± 13.5 and im = 14.3 ± 10.6 %. Ninety-six hours after iv and im administration, residues of the drug were not found in milk. In conclusion, ceftazidime, when administered to goats, showed high concentration times in serum, good penetration into milk and a bioavailability that makes it suitable to be used by the im route.

[Binding of tylosin, tilmicosin and oxytetracycline to proteins from honeybees, larvae and beehive products]

American Foulbrood (AFB) caused by the spore-forming bacterium Paenibacillus larvae is the most serious disease of bacterial origin affecting larvae and pupae of honeybees. Antibiotics are used in many countries for the control of AFB in high incidence areas, but their misuse may lead to antibiotic resistance of bacterial strains and honey contamination. The objective of the present work was to determine, through a biological method, the protein binding of tylosin, tilmicosin and oxytetracycline to worker jelly; honey; pollen; adult bees and larvae in order to propose their kinetic routes. The sensitivity limit of the technique used was 0.05 μg/ml for tylosin and tilmicosin and 0.01 μg/ml for oxytetracycline, respectively. The method had intra and inter-assay correlation coefficients over 0.90, respectively and a coefficient variation of intra-and inter-assay for all antibiotics and processed samples under 5%. Tylosin and oxytetracycline presented lower percentages of protein binding in tissues and hive products (average 15%) in relation to those observed for tilmicosin (29%). In conclusion, tylosin is useful for AFB control in honey bee colonies due to its chemical characteristics, antimicrobial activity and levels of protein binding in bees, larvae, and beehive products.

Effect of physical activity on the pharmacokinetics of ceftazidime in mice

BACKGROUND

The aim of the present work was to assess comparatively the pharmacokinetic profile of ceftazidime (CAZ) in trained and non-trained mice.

METHODS

The study was performed on 256 mice divided at random into four groups: long-term physically trained mice with (E1a) and without (E1b) physical activity prior to the administration of CAZ, and untrained mice with (E2a) and without (E2b) physical activity prior to the administration of the antibiotic. CAZ was administered intramuscularly (25 mg/kg) to all mice, and blood samples were obtained at different time points. The plasma concentrations of CAZ were determined by HPLC and analyzed by non-compartmental models.

RESULTS

The area under the curves in groups E1a and E2a (27.3 and 22.9 microg x ml(-1) x h, respectively) were different compared to the other groups [(E1b) = 11.1 and (E2b) = 15.6 microg x ml(-1) x h; p < 0.05]. Differences were observed between the concentration-time of CAZ in E1a compared to E1b, E1a versus E2a, E1a versus E2b, E1b versus E2a and E1b versus E2b (p < 0.05).

CONCLUSION

Physical activity performed prior to CAZ administration modified the pharmacokinetic profile of the drug administered to mice.

Early detection and longitudinal changes in amyotrophic lateral sclerosis by (1)H MRSI

OBJECTIVE

To determine 1) the reproducibility of metabolite measurements by (1)H MRS in the motor cortex; 2) the extent to which (1)H MRS imaging (MRSI) detects abnormal concentrations of N-acetylaspartate (NAA)-, choline (Cho)-, and creatine (Cre)-containing compounds in early stages of ALS; and 3) the metabolite changes over time in ALS.

METHODS

Sixteen patients with definite or probable ALS, 12 with possible or suspected ALS, and 12 healthy controls underwent structural MRI and multislice (1)H MRSI. (1)H MRSI data were coregistered with tissue-segmented MRI data to obtain concentrations of NAA, Cre, and Cho in the left and right motor cortex and in gray matter and white matter of nonmotor regions in the brain.

RESULTS

The interclass correlation coefficient of NAA was 0.53 in the motor cortex tissue and 0.83 in nonmotor cortex tissue. When cross-sectional data for patients were compared with those for controls, the NAA/(Cre + Cho) ratio in the motor cortex region was significantly reduced, primarily due to increases in Cre and Cho and a decrease in NAA concentrations. A similar, although not significant, trend of increased Cho and Cre and reduced NAA levels was also observed for patients with possible or suspected ALS. Furthermore, in longitudinal studies, decreases in NAA, Cre, and Cho concentrations were detected in motor cortex but not in nonmotor regions in ALS.

CONCLUSION

Metabolite changes measured by (1)H MRSI may provide a surrogate marker of ALS that can aid detection of early disease and monitor progression and treatment response.

Pharmacokinetics and residues in milk of oxytetracyclines administered parenterally to dairy goats

OBJECTIVE

To determine for two commercial preparations of oxytetracycline (OTC) the pharmacokinetic behaviour, the presence of detectable milk residues and the penetration in milk of OTC administered by intravenous (IV) (conventional formulation [CF]) and intramuscular (IM) routes (CF and long-acting [LA] formulations) in goats producing milk. The effects of these formulations on plasma activity values of creatine kinase (CK) and lactate dehydrogenase (LDH) were also determined as indicators of tissue damage.

PROCEDURE

Five healthy lactating goats producing 1.5+/-0.5 L/d milk and weighing 56.0+/-4.8 kg were used. Single doses of OTC chlorhydrate (CF) were administered (20 mg OTC/kg) by IV (Trial 1 IV) and IM (Trial 1 IM) routes and OTC dehydrate (LA) by the IM route. The same goats were first given IV CF, then IM CF followed by IM LA with 3 weeks between each treatment. Blood and milk samples were taken. The quantification of OTC was performed by HPLC and the plasma activities of CK and LDH enzymes were determined by spectrophotometry. The presence of OTC residues in milk was determined by a commercial reagent. The plasma pharmacokinetic parameters were calculated using a two-compartment model.

RESULTS

Estimates of kinetic variables following IV administration were: Vss= 400.0+/-120.0 mL/kg and CL= 110.0+/-14.0 (mL/h)/kg. The t(fi) for IV= 3.0+/-0.3 h; IM, CF = 10.5+/-2.1 h and IM, LA = 15.1+/-3.1 h. The concentration of OTC in milk at 48 h was: IV= 0.6+/-0.4; IM CF= 1.1+/-0.2 and at 72 h (IM LA)= 0.6+/-0.1 microg/mL and the penetration in milk of OTC was: IV= 70.0+/-18.0; IM CF= 79.0+/-14.0 and IM LA= 66.0+/-6.0%. The areas under the curve of CK and LDH activities in plasma were calculated by the trapezoidal method. Values of CK and LDH IM, LA were greater (P < 0.05) than those observed for IM, CF at 2 and 3 days after administration of the antibiotic. Finally, the bioavailability of OTC CF = 92.0+/-22.0 and LA= 78.0+/-23.0% was suitable for its usage by the IM route in lactating goats.

CONCLUSION

Plasma concentration-time values of OTC administered parenterally in production dairy goats showed similar bioavailability for the two pharmaceutical preaprations. The presence of detectable residues in milk indicates that milk should not be used for human consumption for 2 and 3 days after administration of conventional and long-acting formulations, respectively. The increments in CK and LDH activities after the IM administration of LA are consistent with the presence of tissue damage provoked by the pharmaceutical preparations at the injection site.

Pharmacokinetics and penetration into tissue fluid of ceftizoxime in normal and hyperthermic sheep

The pharmacokinetics of ceftizoxime was studied in six sheep before and after inducing hyperthermia using Escherichia coli endotoxin. Sheep implanted subcutaneously with cages of non-reactive material for collecting tissue cage fluid (TCF) were used to conduct two trials. In Trial 1 animals with normal basal temperature (normal sheep (NS)) were given intravenous (i.v.) and intramuscular (i.m.) monodoses of ceftizoxime (20mg/kg BW) at 1 week interval. One and 5 weeks later (Trial 2) each sheep were injected 1µg/kg BW of endotoxin to produce hyperthermia (hyperthermic sheep (HS)) previously to i.v. administration (HSi.v.) and i.m. (HSi.m.) of ceftizoxime (20mg/kg BW), respectively. Serum and TCF samples were collected over 6h post-administration. Ceftizoxime concentrations in serum and TCF were determined by a microbiological assay. The concentrations in serum and TCF of ceftizoxime were analyzed through compartmental and non-compartmental models.Rectal temperature were significantly incremented in all animals during Trial 2. The half-time and constant of elimination in serum of ceftizoxime in NSi.v. (t(1/2)=1.1+/-0.4h; lambda(z)=0.7+/-0.2h(-1)) were statistically different those observed in HSi.v. (t(1/2)=1.4+/-0.4h; lambda(z)=0.5+/-0.2h(-1)). The constants of distribution in NSi.v. and HSIV were 5.1+/-4.6 and 4.1+/-3.4h(-1), respectively. The time to reach the maximum concentrations in TCF was latter (p<0.05) in NS (t(max)=2.3+/-0.7h) than in HS (t(max)=1.3+/-0.6 h). After i.m. administration in NS the absorption half-life (0.12+/-0.19h) was latter (p<0.05) than in HS (0.06+/-0.007h) with greater areas under the curve (AUC in NS=65.4+/-20.8 and AUC in HS=34.7+/-7.5 (µg/ml) h). The maximum value of concentration in serum (C(max)) and AUC in TCF were greater (p<0.05) in NS (C(max)=46.1+/-10.6µg/ml and AUC=84.4+/-17.4 (µg/ml) h) as compared to same HS (C(max)=27.0+/-12.9µg/ml and AUC=47.9+/-3.9 (µg/ml) h). The concentrations of ceftizoxime in TCF after i.v. and i.m. in NS and HS were elevated during a 6h period after administration. The bioavailability of ceftizoxime in NS (101.6+/-59.9%) and HS (87.4+/-63.3%) was suitable for its use by the i.m. route.

Treatment of anaphylactic sensitivity to peanuts by immunotherapy with injections of aqueous peanut extract

BACKGROUND

Immediate hypersensitivity to peanuts is a frequent cause of anaphylactic reactions and deaths in children and adults. Currently, preventive treatment consists of avoidance, which is difficult because of the widespread and often disguised use of peanuts in the food industry.

METHODS

Twelve patients with immediate hypersensitivity to ingestion of peanuts were recruited. Half were treated with injections of peanut extract: a maintenance level of tolerance was first achieved by a rush protocol, then maintained with weekly injections for at least 1 year. The other six were untreated control subjects. All patients underwent double-blind, placebo-controlled, oral peanut challenges initially, after approximately 6 weeks, and after 1 year.

RESULTS

All treated patients achieved the maintenance dose of 0.5 ml of 1:100 wt/vol peanut extract by the rush injection protocol. All experienced increased tolerance to double-blind, placebo-controlled peanut challenge and decreased sensitivity on titrated skin prick testing with peanut extract, whereas the threshold to oral peanut challenge and cutaneous reactivity to peanut extract were unchanged in the untreated control subjects. Systemic reactions were common in the treated group both during rush immunotherapy and with maintenance injections. Only three patients remained tolerant of the full maintenance dose. The increased tolerance to oral peanut challenge was maintained in the three subjects who received full maintenance doses, but there was partial (n = 2) or complete (n = 1) loss of protection in the patients who required dose reduction because of systemic reactions.

CONCLUSIONS

Injections of peanut extract increase the tolerance of patients with peanut allergy to oral ingestion of peanuts. Injections result in repeated systemic reactions in most patients, even during maintenance injections. For clinical application of this method of treatment, a modified peanut extract is needed.

The pharmacokinetics of ceftazidime in lactating and non-lactating cows

The pharmacokinetics of ceftazidime (CAZ) were studied in lactating (LTG) and non-lactating (NLTG) cows. Two groups (LTG and NLTG) of 5 healthy dairy cows were given ceftazidime (10 mg/ kg body weight) intravenously (i.v.) and intramuscularly (i.m.). Serum and milk (LTG) and serum samples (NLTG) were collected over a 24-h period post-administration. CAZ concentrations in serum and milk were determined by high-performance liquid chromatography, and an interactive and weighted-non-linear least-squares regression analysis was used to perform the pharmacokinetic analysis. The pharmacokinetic profiles in LTG and NLTG cows which had received CAZ i.v. fitted a three-compartment model and a two-compartment model, respectively. The CAZ concentration-time curves in serum and the area under the curve were greater and more sustained (p < 0.05) in the LTG cows by both routes, while the serum clearance (Cls = 72.5 +/- 18.1 ml/h per kg) was lower (p < 0.05) than that in the NLTG cows (Cls = 185.9 +/- 44.2 ml/h per kg). CAZ given i.v. exhibited a relatively long half-life of elimination (t1/2 beta (LTG) = 1.1 +/- 0.2 h; t1/2 beta (NLTG) = 1.4 +/- 0.3 h). Compared with other cephalosporins, CAZ had good penetration into the mammary gland (47.7 +/- 38.2% for CAZ i.v.; 51.1 +/- 39.0% for CAZ i.m.). Finally, the bioavailability of CAZ (F(LTG) = 98.9 +/- 36.8%; F(NLTG) = 77.1 +/- 25.3%) was suitable for its used by the i.m. route in lactating and non-lactating cows.

Pharmacokinetics and penetration into tissue fluid of cefotaxime in bovines

Concentrations of cefotaxime in serum and tissue fluid were studied in the bovine after intravenous and intramuscular administration at a dosage of 10 mg.kg-1 body weight. Steers implanted subcutaneously with tissue cages were used. After intravenous bolus administration, profiles of mean concentrations in serum over time were described by a two-compartment open model. The rate constant of elimination was 1.4 +/- 0.3 h-1 and the half-life 0.6 +/- 0.1 h. The rate constant of distribution was 11.5 +/- 1.9 h-1, and the half-life was 0.06 +/- 0.01 h. The volume of distribution at steady state was 250.6 +/- 37.3 ml.kg-1. The area under the curve was 31.8 +/- 7.4 micrograms.ml-1.h. The penetration ratio into tissue fluid was 36.5 +/- 15.4%. After intramuscular injection, the half-life was 1.1 +/- 0.3 h, the area under the curve was 27.5 +/- 6.8 micrograms.ml-1.h, and the penetration ratio into tissue fluid was 47.1 +/- 15.8%. The concentrations in tissue fluid after intravenous and intramuscular administration of cefotaxime were elevated during a 6-hour period after administration.

The interaction between ruptured erythrocytes and low-density lipoproteins

Low-density lipoproteins (LDL) are oxidatively modified on interaction with haem proteins. The interaction of ruptured erythrocytes with LDL induces oxidative damage as detected by alterations in electrophoretic mobility and the peroxidation of the polyunsaturated fatty acyl chains. Difference spectroscopy reveals that the amplification of the oxidative process by the haem protein is related to the transition of the oxidation state of the haemoglobin in the erythrocyte lysate from the oxy [X-FeII-O2] to the ferryl [X-FeIV = O] form. The incorporation of the lipid-soluble antioxidant, butylated hydroxy toluene, at specific time points during the LDL-erythrocyte interaction prolongs the lag phase to oxidation and eliminates the oxy-to-ferryl conversion of the haemoglobin. The timescale of this haem conversion is related to the antioxidant status of the LDL.

Pharmacokinetics of ceftazidime in sheep and its penetration into tissue and peritoneal fluids

Serum, tissue and peritoneal fluid concentrations of ceftazidime were studied in ewes after intravenous, intramuscular and subcutaneous administration at 50 mg kg-1 bodyweight. Tissue and peritoneal cages were implanted in the animals studied. After intravenous bolus administration, the mean serum concentration versus time profile was best described by a two-compartment open model. The distribution rate constant (alpha) was 3.5 +/- 1.1 h-1 and the half-life (t 1/2 alpha) 0.22 +/- 0.09 hour. The elimination rate constant (beta) was 0.43 +/- 0.04 h-1 and half-life (t 1/2 beta) 1.6 +/- 0.2 hours. The area under the curve was 275.7 +/- 84.0 micrograms.ml-1 h. The volume of distribution as steady state was 356.1 +/- 208.0 ml kg-1. The penetration ratio into tissue fluid was 62.6 +/- 15.1 per cent and into peritoneal fluid 61.1 +/- 16.5 per cent. After intramuscular injection, the elimination half-life was 1.7 +/- 0.2 hours, the area under the curve was 228.7 +/- 43.3 micrograms.ml-1 h. and the elimination rate constant was 0.42 +/- 0.05 h-1. The penetration ratio into tissue fluid was 68.5 +/- 37.3 per cent and into peritoneal fluid 73.3 +/- 34.4 per cent. After subcutaneous injection, the elimination half-life was 1.8 +/- 0.5 hours, the area under the curve was 231.8 +/- 65.6 micrograms.ml-1 h. and the elimination constant was 0.41 +/- 0.10 h-1. The penetration ratio into tissue fluid was 47.2 +/- 3.5 per cent and into peritoneal fluid 58.1 +/- 15.6 per cent.(ABSTRACT TRUNCATED AT 250 WORDS)