Influence of the genotype of Staphylococcus aureus, determined by pulsed-field gel electrophoresis, on dry-period elimination of subclinical mastitis in Canadian dairy herds

By combining information from 2 databases, we investigated the possibility of an association between the genotype of Staphylococcus aureus causing bovine intramammary infection and dry-period cure of subclinical infection. The 1st database contained bacteriologic and cow data from a field study evaluating the efficacy in such infections of a new intramammary dry-cow therapy (DCT) containing tilmicosin phosphate, in comparison with a commercially available DCT containing benzathine cloxacillin. Isolates of S. aureus from that study were frozen and later independently analyzed by pulsed-field gel electrophoresis (PFGE) and macrorestriction DNA fingerprinting. The molecular information, summarized and published elsewhere, constituted the 2nd database. Data from 121 subclinically infected quarters of 92 cows from 40 herds were studied by univariate and multivariable regression analysis. Infection by an isolate of PFGE lineage group D was more likely than infection by an isolate of group A or F to be cured (P < 0.05). Cows infected by lineage group D had a higher linear somatic cell count score (LS) from the last Dairy Herd Improvement test before the dry period than did cows infected by the other lineage groups (P = 0.04). Although the probability of cure was significantly lower for cows with an LS at or above the mean of 5.7 for the study population (P = 0.05), when such a cow was infected with lineage group D, cure was significantly more likely (P < 0.001) than when it was infected by another lineage group. Significantly more (P = 0.02) of the infections treated with tilmicosin (74%) than of those treated with benzathine cloxacillin (53%) were cured, and significantly more (P = 0.05) of the infections by group D (81%) than of those by group A (57%) or group F (54%) were cured. However, there was no difference in cure rate for any PFGE genotype when tilmicosin phosphate was administered; when benzathine cloxacillin was administered, 87% of lineage group D isolates were eliminated, as compared with 46% of group A and 33% of group F isolates (P < 0.05). This research demonstrates that certain genotypes of S. aureus may naturally elicit a greater inflammatory response, yet be more susceptible to elimination by antibiotics in the dry period, than other genotypes.

Efficacy of intramammary tilmicosin and risk factors for cure of Staphylococcus aureus infection in the dry period

The objective ofthis study was to evaluate the efficacy of intramammary tilmicosin, administered at drying-off, for eliminating Staphylococcus aureus infection, and to identify risk factors for S. aureus cure during the dry period. A total of 219 naturally infected cows, representing 308 quarters, were randomized to receive either one of two treatments at drying-off. Cows received either an intramammary infusion of 500 mg of benzathine cloxacillin, or a sterile solution containing 1,500 mg of tilmicosin. All cows had quarter milk samples taken aseptically three times before dry-off, and at wk 1, 2, and 4 of the subsequent lactation. Overall, 62% of cows and 67.5% of quarters infected with S. aureus cured during the dry period. The cure following administraton of tilmicosin was 67.3 and 72.5% for cows and quarters, respectively. By comparison, the cure achieved with cloxacillin was 56.9 and 62.9% of cows and quarters. Cows receiving tilmicosin were 2.1 times more likely to cure. The cure rate for cows decreased as the linear score on the last DHI test increased, and as the amount of S. aureus being shed increased. Quarters that cultured positive multiple times before drying-off were less likely to cure. Staphylococcus aureus infections located in front quarters of the udder were 2 times more likely to cure than those in hind quarters. Results of this study demonstrate that intramammary tilmicosin at drying-off is efficacious in curing existing S. aureus during the dry period. Risk factors associated with the cure of S. aureus were identified.

The synthesis and evaluation of 6-alkylidene-2'beta-substituted penam sulfones as beta-lactamase inhibitors

Penicillin sulfones, which structurally incorporate both a 6-position alkylidene substituent and a 2'beta substituent, have been synthesized and evaluated as inhibitors of class C and class A serine beta-lactamases. Incorporation of the 2'beta-substituent generally improves inhibitory activity. Substituents that improve transport across the bacterial cell membrane have also been incorporated.

Strategies for mastitis control: dry cow therapy and culling

The effects of three selection strategies for dry cow therapy on prevention of new infections and rate of antibiotic usage were compared. Quarter infection status of 1044 cows in 12 herds was determined by bacteriological methods at drying off, calving and three to five months into the following lactation. Cows that were uninfected at drying off were randomly allocated to treatment (whole udder, dry cow therapy) and non-treatment groups. Infected cows were randomly allocated to whole udder or infected quarter only treatments. The strategies compared were blanket treatment (treat all quarters of all cows), selective cow treatment (treat all quarters of any cow infected in one or more quarters) and selective quarter treatment (treat infected quarters only). Selective cow treatment was identified as the preferred strategy. Blanket treatment resulted in increased antibiotic usage (15.5 vs 6.4 tubes per infection eliminated) with no additional benefit, and selective quarter treatment resulted in a higher new infection rate (6.4% vs 3.9% quarters) in the dry period. The prevalence of infection within a herd at drying off had no influence on new infection rates in the dry period or early lactation. The cure rate after dry cow treatment (mean of 66%) decreased significantly with increasing age (P < 0.001). Cows infected in the previous lactation contributed over 76% of infections at calving and nearly 70% at mid-lactation. To lower the incidence of mastitis in a herd, a greater emphasis on culling of older infected cows and prevention of new infections during lactation is needed.

Effects of antibiotic therapy at drying off on mastitis in the dry period and early lactation

Four strategies for selecting cows for intramammary therapy with benzathine cloxacillin at drying off were compared in 12 Victorian dairy herds. The bacteriological status of all quarters of all (1044) cows was determined just before drying off, within 2 d of calving, and again 3 to 5 months after calving. All cases of clinical mastitis (from calving to mid-lactation) were recorded. Cows not infected at drying off were allocated randomly to 2 subgroups of approximately 350 cows each: not infected, not treated (NI-NT), or not infected, all quarters treated (NI-AT). New infection rates in the dry period (3.8% for NI-NT vs 2.1% for NI-AT) and in early lactation (4.1% for NI-NT vs 3.9% for NI-AT) were low and these differences were not significant. Incidence of clinical mastitis in early lactation was almost 50% higher for the treated group of uninfected cows compared with the untreated group (0.05 less than p less than 0.1). Cows infected in one or more quarters at drying off were split randomly into 2 subgroups of approximately 170 cows each: infected, all quarters treated (I-AT), or infected quarters treated only (I-QT). The new infection rate during the dry period was nearly 4 times higher for I-QT (15.3%) due to significantly more new infections by Staphylococcus aureus and Streptococcus uberis.(ABSTRACT TRUNCATED AT 250 WORDS)

[Therapy of bacterial pharyngo-tonsillitis in children with piperacillin-flucloxacillin combination]

The authors evaluated the activity and safety of piperacillin/flucloxacillin in 40 children suffering from bacterial pharyngo-tonsillitis. The combination proved to be effective with regard to this pathology and no toxic or allergic side-effects were reported. This confirms the wide spectrum of the antibiotic.

Flucloxacillin induced delayed cholestatic hepatitis

We report four cases of severe delayed cholestatic hepatitis induced by flucloxacillin. All patients presented with deep jaundice and pruritus which developed soon after ceasing flucloxacillin. Liver function tests were abnormal in all patients with markedly elevated serum bilirubin concentration, alkaline phosphatase and aspartate transaminase levels. Extrahepatic biliary obstruction and infective hepatitis were excluded in all cases. Liver biopsies showed centrilobular cholestasis with portal and lobular inflammation and eosinophil infiltration. Although symptoms resolved within six weeks in all patients, cholestatic liver function tests have persisted in two patients for more than six months. With the increasing usage of this drug and the delayed presentation of cholestasis, flucloxacillin needs to be considered in the differential diagnosis of all patients presenting with cholestatic jaundice.

Effects of bovine mammary secretion during the early nonlactating period and antibiotics on polymorphonuclear neutrophil function and morphology

The effect of bovine mammary secretion during the early nonlactating period and of antibiotic preparations on bovine polymorphonuclear neutrophil (PMN) phagocytic function and morphology were evaluated in a series of in vitro multifactorial experiments. Benzathine cloxacillin (CL), benzathine cephapirin (CE), sodium novobiocin (NO), and a combination of dihydrostreptomycin with procaine penicillin G (DP) were prepared in the presence and absence of a peanut oil aluminum monostearate vehicle. The PMN were isolated from bovine blood, and the effect of each antibiotic preparation on PMN function and morphology was evaluated in a buffer, fat, skin, and a combination of fat with skim from bovine mammary secretion during the nonlactating period. The fat and skim were diluted with buffer to approximate their concentration in mammary secretion. Phagocytic functions of PMN were monitored by fluorescent microscopy, which made it possible to estimate both ingestion and intracellular killing of bacteria by PMN. Changes in PMN morphology were monitored by transmission electron microscopy. The ability of PMN to ingest and kill Staphylococcus aureus ATCC 25923 was significantly decreased by fat, skim, CL, CE, NO, and DP. Effects of some antibiotics on ingestion and killing of bacteria by PMN were influenced by the addition of vehicle and by interactions with mammary secretion. Neutrophil morphology was altered by fat, skim, CL, CE, NO, and DP. The detrimental effects of CL, CE, NO, and DP on PMN morphology were influenced (some significantly) by the presence of vehicle and interactions with mammary secretion. There were significant correlations among secretion- and antibiotic-induced changes in PMN ingestion of bacteria, PMN killing of bacteria, and PMN morphology.

Topically applied benzathine cloxacillin for treatment of experimentally induced infectious bovine keratoconjunctivitis

The efficacy of an ophthalmic ointment containing benzathine cloxacillin for treatment of infectious bovine keratoconjunctivitis was determined in 2 experiments. In the first experiment, Holstein calves (n = 6/group) were inoculated with Moraxella bovis and treated on postinoculation days 3 and 6 with either topically applied benzathine cloxacillin (250 mg/eye) or long-acting oxytetracycline formulation (20 mg/kg of body weight, IM). A third group of inoculated calves remained untreated as controls. For the second experiment, 4 groups of calves (n = 6/group) were inoculated and treated on postinoculation days 3 and 6 with 50, 125, 250, or 375 mg of benzathine cloxacillin; a fifth untreated group served as controls. Ocular specimens were obtained for microbiologic culture, and eyes were observed and assigned a clinical score daily. Eyes were photographed on alternate days. Ulcer surface area was measured, using a planimeter. In experiment 1, the week-2 ulcer surface area measurements for both groups of treated calves were smaller than those for controls. There was a greater frequency of M bovis isolation from the ocular secretions of controls than from those of benzathine cloxacillin-treated calves during postinoculation weeks 2 and 3. The number of M bovis isolations from the benzathine cloxacillin- and oxytetracycline-treated calves was not significantly different at any sample collection interval. On week 3, the scores of the benzathine cloxacillin-treated calves were smaller than those of controls. In experiment 2, calves of the 250- and 375-mg groups had smaller ulcer surface area measurements than did controls on week 2. By week 3, calves of the 375-mg group had smaller scores than did controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Ocular and serum disposition kinetics of cloxacillin after topical administration of benzathine cloxacillin and intravenous administration of sodium cloxacillin to calves

Disposition kinetics of cloxacillin were examined in calves after topical administration of benzathine cloxacillin and single IV administration of sodium cloxacillin, and the susceptibility of 17 field isolates of Moraxella bovis was measured. For the IV pharmacokinetic phase, sodium cloxacillin was administered at dosage of 10 mg/kg of body weight to male Holstein calves (n = 6, weighing 146 to 170 kg), and serum concentration of cloxacillin was measured thereafter for 10 hours. For the ocular pharmacokinetic phase, 6 calves were given either of 4 benzathine cloxacillin topical formulations consisting of 50-, 125-, 250-, or 375-mg doses. Treatment was repeated every 10 days until all 4 benzathine cloxacillin dosages were tested in the same 6 calves. Blood and tears were collected for 72 hours after each benzathine cloxacillin formulation was administered, and the concentration of cloxacillin in each specimen was measured, using a bioassay. The minimal inhibitory concentration of cloxacillin for 17 field isolates of M bovis was determined by use of an agar pour-plate dilution assay. After single IV administration of sodium cloxacillin, its half-life, body clearance, and volume of distribution were 19.5 +/- 12.8 minutes, 18.3 +/- 2.2 ml/min.kg, and 496 +/- 290 ml/kg, respectively. After topical administration of benzathine cloxacillin, cloxacillin concentration in lacrimal fluid peaked between 30 and 45 minutes and ranged between 963 micrograms/ml and 3,256 micrograms/ml for the 125- and 375-mg doses, respectively. There was no detectable cloxacillin activity in the lacrimal fluid of any calf by 36 hours after topical administration of benzathine cloxacillin, and cloxacillin was not detected in the serum at any time.(ABSTRACT TRUNCATED AT 250 WORDS)

A randomised comparison of ceftazidime and piperacillin, both in combination with flucloxacillin for treatment of febrile episodes in neutropenic children. Finnish Three-Centre Study

111 febrile episodes in 98 neutropenic children were randomly treated with either ceftazidime (CAZ) 150 mg/kg/day or with piperacillin (PIP) 200 mg/kg/day, both combined with flucloxacillin (FLUC) 50 mg/kg/day. A total of 37/47 (79%) eligible episodes in the CAZ group and 41/53 (77%) in the PIP group were cured without needing to stop the initial therapy. The success without modification of the treatment in the verified septicaemias in the CAZ group was 8/18 (44%) and in the PIP group 5/18 (28%). Of the bacteriologically documented infections, 13/24 (54%) in the CAZ group and 11/24 (46%) in the PIP group were cured without modification of the therapy. Similarly, 17/31 (55%) of all the isolated bacteria in the CAZ group and 14/33 (42%) in the PIP group were eradicated with the initial therapy. Overall there were 13 deaths of which 4 in the CAZ group and 5 in the PIP group occurred during the infection. An increasing granulocyte count exceeding 0.25 x 10(9)/l at the end of the therapy was a good prognostic sign for the outcome of the infection. This study indicates that CAZ is as effective as PIP in the treatment of infections in neutropenic children.

Prolonged hepatic cholestasis after flucloxacillin therapy

A severe prolonged illness that was characterized by deep jaundice and debilitating pruritus occurred in five patients after the use of flucloxacillin. The symptoms and signs of liver disease took at least two months to resolve; after four- to nine-months' follow-up, liver enzyme activities have remained abnormal in all patients. Examination of liver biopsy specimens showed severe cholestasis in all cases, with evidence of significant bile-duct injury in three cases. In one patient, in whom symptoms have persisted for nine months, examination of a liver biopsy specimen showed marked bile-duct depletion. All patients were seen during a four-month period and it is felt that flucloxacillin-induced liver disease probably has been under-diagnosed and underreported. The use of flucloxacillin has been increasing rapidly and it is anticipated that more cases of flucloxacillin hepatotoxicity will occur in the future.

Effectiveness of two benzathine cloxacillin formulations for treatment of naturally occurring infectious bovine keratoconjunctivitis

A field study was performed to determine the effectiveness of benzathine cloxacillin for the treatment of infectious bovine keratoconjunctivitis in cattle from 2 farms located in northern California. The study was performed between June and September of 1987. Affected calves ranging from 2 to 9 months of age were selected from the main herd when signs of corneal ulceration were observed. The study was conducted in 2 phases. For phase I, the affected calves of herd 1 (n = 21; Holsteins) and herd 2 (n = 43 Angus crossbred), were randomly assigned to 1 of 3 groups, and were either treated with 250 (n = 23) or 375 mg (n = 21) of benzathine cloxacillin, or mineral oil (n = 20) on days 1 and 4. For phase II, affected calves (n = 16; Angus crossbred, 3 to 9 months of age) from herd 2 were treated with benzathine cloxacillin (250 mg). Eight of these calves were retreated on day 4. After treatment, all calves were examined every 72 hours for 16 days. For examinations, a clinical score was assigned to each eye, and the surface areas of photographed corneal ulcers were measured. The ocular secretions were collected and examined culturally for Moraxella bovis. On days 7, 10, and 13, the calves treated with benzathine cloxacillin had significantly (P less than 0.05) lower lesion scores, compared with the controls.(ABSTRACT TRUNCATED AT 250 WORDS)

The efficacy of the combination of teicoplanin or flucloxacillin with netilmicin in the treatment of Staphylococcus aureus bacteraemia

Twenty one patients with serious Staphylococcus aureus infection and bacteraemia were randomized prospectively to receive either teicoplanin and netilmicin or flucloxacillin and netilmicin. After at least 48 h of treatment serum samples were collected for the determination of trough and peak antibiotic concentrations, the serum killing level and the serum bactericidal rate. With the help of a severity-of-disease scoring system (APACHE II) the clinical efficacy of antimicrobial therapy was assessed. Eighteen patients were evaluable. The clinical results and the results of the serum assays suggest that treatment with teicoplanin or flucloxacillin, combined with netilmicin, is a safe approach in patients with bacteraemia caused by S. aureus.

Flucloxacillin compared with cefazolin in short-term prophylaxis for clean orthopedic surgery

Two-hundred and fifty-two patients were included in a prospective, randomized, double-blind trial comparing the efficacy of flucloxacillin with that of cefazolin for clean orthopedic surgery. The preventive antibiotic regimen consisted of three 1-g injections perioperatively. There were 126 patients in each group, and the follow-up period was at least 6 months. Two deep (1.6%) and five superficial (4.0%) infections occurred in the flucloxacillin group. Three deep (2.4%) and five superficial (4.0%) infections developed in the cefazolin group.

Factors influencing the biological inactivation of high protein bound beta-lactam antibiotics in vitro

Unpredictable inactivation of antimicrobial agents may cause erratic results in pharmacokinetic studies. In this study we followed the inactivation of the high protein bound beta-lactams flucloxacillin, dicloxacillin and ceftriaxone in vitro. The antibiotics were added to pools of human and rabbit sera, ultrafiltrates of these pools, rabbit interstitial fluid, phosphate buffered saline (PBS), rabbit albumin in PBS and sodium dodecyl sulphate (SDS) treated preparations of human sera. Ceftriaxone was relatively stable but different serum pools varied significantly in their flucloxacillin and dicloxacillin inactivating capacity. The dominating inactivation took place within five minutes after the addition of antibiotics to serum. The inactivating factor was heat stable at 56 degrees C, 0.5 h, of relatively high molecular weight, and not related to albumin. The inactivating capacity could be diminished by SDS-treatment of serum suggesting a lipoprotein nature.

Amino acid sequence, active-site residue, and effect of suicide inhibitors on cephalosporinase of Citrobacter freundii GN346

The structural gene for a cephalosporinase of Citrobacter freundii GN346 was sequenced. From the nucleotide sequence, the entire amino acid sequence of the mature enzyme with 361 amino acids and a molecular weight of 39,867 was determined. The active-site serine was directly confirmed to be serine 64 by studies in which the enzyme was labeled with dansylpenicillin. In investigations comparing the inhibitory effect of sulbactam (penicillanic acid sulfone) and cloxacillin sulfone on the cephalosporinase and on TEM-2-type penicillinase, sulbactam was found to be an effective progressive inhibitor but a poor competitive inhibitor for the cephalosporinase. The cephalosporinase and the inhibitor formed a long-lived complex with a half-life of 550 minutes. Cloxacillin sulfone could not inactivate the cephalosporinase progressively but irreversibly inactivated the penicillinase.

Sweat tests and flucloxacillin

Sweat tests were carried out on 14 patients with cystic fibrosis and 14 controls when on no antibiotics and when taking oral flucloxacillin. No significant differences in results were obtained for either group whether on or off antibiotics. Oral flucloxacillin does not affect sweat electrolytes and is not a contraindication to sweat testing.

Concentrations of flucloxacillin in heart valves and subcutaneous and muscle tissues of patients undergoing open-heart surgery

Thirty-seven patients were given a single, 2-g intravenous bolus injection of flucloxacillin prior to open-heart surgery. Within 12 h, flucloxacillin concentrations in serum and heart valves declined from 125.2 to 4.4 micrograms/ml and from 16.5 to 3.7 micrograms/g, respectively. Concentrations in subcutaneous tissue and muscle were almost identical, declining from 14.7 or 14.2 micrograms/g to undetectable levels after 8 to 10 h.

Cephradine and flucloxacillin in the prophylaxis of infection in patients with open fractures

A comparison of prophylactic antibiotic cover of cephradine or flucloxacillin in sixty patients with open fractures is reported. There were more infections in the flucloxacillin than in the cephradine group and gastrointestinal side-effects were more common. The overall incidence of infection in the whole group, two out of 60 or 3.3%, was acceptably low.

Optimization of high-performance liquid chromatographic analysis for isoxazolyl penicillins using factorial design

A 3 X 3 factorial design has been used to study the effects of pH and acetonitrile concentration of the eluents on the retention and resolution of cloxacillin, flucloxacillin and dicloxacillin on a C18 column. The logarithm of the capacity factors of these solutes have been found to vary linearly with the pH and quadratically with the acetonitrile content. The equations generated have been employed to predict experimental conditions necessary for an optimum separation. The chromatographic condition selected has been applied to the quantitation of flucloxacillin in human plasma using dicloxacillin as the interval standard. Sample preparation consists of protein precipitation and solid-phase extraction. The detection limit of the assay at 220 nm for flucloxacillin is in the region of 0.1 microgram/ml. This assay has been employed in a study of the relative bioavailability of two commercial flucloxacillin sodium capsules in ten healthy volunteers.

pH and P.E.G.-400 effects on flucloxacillin absorption

1. Intestinal clearances of flucloxacillin significantly decrease with the increase of pH, concomitantly with a decrease of the percent absorbed at 60 min. 2. The apparent rate constants for unionized (Ku) and ionized species are 0.173 min-1 and 0.017 min-1 respectively. 3. The addition of P.E.G.-400 at different concentrations significantly enhanced intestinal clearances of flucloxacillin parallel to an increase of net water flux from the lumen of the small intestine.

The penetration of antibiotics into the normal intervertebral disc

The role of antibiotics in the treatment of disc-space infection is controversial. This study assessed the tissue penetration of flucloxacillin and cephradine into the normal intervertebral disc after intravenous administration of a bolus dose of antibiotic. Twenty-five discs were removed from 12 adolescent patients having anterior spinal surgery to correct scoliosis; antibiotic had been administered between 30 minutes and four hours before operation. Despite high blood levels, no antibiotic could be detected by bioassay or by high-pressure liquid chromatography (h.p.l.c.) in any of the specimens from the nucleus pulposus or the annulus fibrosus.

A controlled trial of nebulized aminoglycoside and oral flucloxacillin versus placebo in the outpatient management of children with cystic fibrosis

Six children with cystic fibrosis who had persistently had Pseudomonas aeruginosa isolated from their respiratory tract, completed a double-blind cross-over comparison of oral flucloxacillin and nebulized aminoglycoside versus double placebo. The patients had higher FEV1 results at the end of the month of active treatment than after the month of placebo.

Antibiotic levels in bovine lacrimal fluid after single application of ointments containing procaine benzyl penicillin plus dihydrostreptomycin; and benzathine cloxacillin

The efficacy of an experimental slow-release formulation, containing procaine benzyl penicillin and dihydrostreptomycin, was investigated in a cross-over study with a cloxacillin eye ointment in 12 cows with clinically normal eyes. After a single topical application the therapeutic concentrations of penicillin were sustained for 48 to 92 hours and of cloxacillin for 32 to 48 hours. These long-acting ointments will simplify the successful treatment of painful eye disorders such as keratoconjunctivitis. A practical and non-irritant method for sampling tears is described.

Flucloxacillin in chronic leg ulcers. Penetration of flucloxacillin into chronic leg ulcer exudate and the effect on the bacteria

The penetration of flucloxacillin into ulcer exudate was investigated in six patients with chronic leg ulcers. The flucloxacillin dosage used was 1 g orally three times daily for three days, and the serum and exudate concentrations were measured repeatedly during a 10 h-period following the first and the seventh dose. All the ulcers were contaminated with (S. aureus) Staphylococcus aureus either in pure culture (three ulcers) or in culture mixed with Gram-negative bacteria (three ulcers). Bacterial counting in the ulcers was performed twice before and twice during the antibiotic treatment. The flucloxacillin concentrations measured in the ulcer exudate were found to be lower than the corresponding serum concentrations. However, the exudate concentrations were found to be above the minimum inhibitory concentration (MIC) for the contaminating S. aureus during an average of 7 h after each dose, and the number of S. aureus during the treatment period was reduced to less than 0.01% of the initial number. The Gram-negative bacteria were not susceptible to flucloxacillin. The number of these bacteria decreased before flucloxacillin treatment but increased again during treatment, probably owing to the changed conditions in the ulcers following the marked decrease in the number of S. aureus.

The influence of flucloxacillin and amoxicillin with clavulanic acid on the aerobic flora of the alimentary tract

In a randomized study, 42 patients undergoing extensive maxillo-facial surgery (correction of the position of the mandible or maxilla by using autologous bone transplants) received prophylactically ten-day courses of either flucloxacillin or amoxicillin with clavulanic acid. Patients were comparable with regard to age and type of surgery. During the prophylactic treatment the effect of antibiotics used on the microbial flora of the alimentary tract was studied. Patients receiving flucloxacillin showed increased numbers of Klebsiella spp. isolated from the faeces (59% of the patients versus 19% of the patients receiving amoxicillin with clavulanic acid). Patients receiving amoxicillin with clavulanic acid showed higher colonization rates of oropharynx with Enterobacteriaceae than patients receiving flucloxacillin (ten patients versus five patients). 60% of those strains isolated from patients receiving amoxicillin with clavulanic acid were resistant to this combination, as compared to 20% of gram-negative bacilli isolated from patients receiving flucloxacillin. In 50% of patients receiving amoxicillin with clavulanic acid, colonization of the gut with yeast occurred, as compared to 18% of patients receiving flucloxacillin. Only one infection leading to a partial loss of the graft was seen in the group of patients receiving flucloxacillin.

Floxacillin-induced cholestatic hepatitis with evidence of lymphocyte sensitization

A severe and prolonged form of biopsy-proved cholestatic hepatitis occurred in a 45-year-old man who had received floxacillin for two weeks preceding the episode of drug-related cholestatic injury. Immunologic tests revealed evidence of in vitro sensitization to the drug as well as to the serum of a normal subject collected after ingestion of floxacillin. Floxacillin should be added to the list of drugs causing cholestatic hepatitis, most likely by an immunologic mechanism.

Plasma concentration following oral administration of di- and flucloxacillin in infants and children

The bioavailability of commercial liquid preparations of di- and flucloxacillin was compared in infants and children. The plasma concentrations following a dose of 12.5 mg/kg were equal within the two age groups. Infants 0-1 months old, however, demonstrated a better absorption than older children.

Early termination of a prospective, randomized trial comparing teicoplanin and flucloxacillin for treating severe staphylococcal infections

In a prospective, randomized trial, teicoplanin (at a 400-mg intravenous loading dose followed by 200 mg/day intravenously or intramuscularly) was compared with flucloxacillin (8 g/day) in patients with severe staphylococcal infections. Teicoplanin proved unsatisfactory for the following reasons: failures or relapses were more frequent in the teicoplanin group, and blood levels were difficult to predict and tended to be low 24 hr after the loading dose. Future trials with this agent should use much-higher doses.

Pharmacokinetics of free and total flucloxacillin in newborn infants

Flucloxacillin 50 mg/kg b.w. was administered intravenously (in combination with ampicillin/gentamicin) and orally (with amoxicillin) to 9 newborn infants (gestational age 33-41 weeks) to treat bacterial infections. The concentrations of flucloxacillin in plasma and urine after i.v. injection were analysed according to an open two-compartment model, and the plasma protein binding of flucloxacillin and its distribution to blood cells and plasma water in whole blood were determined. Considerable differences were found from values reported in adults. The terminal half-life averaged 4 h 38 min and was significantly correlated with gestational age. Plasma clearance was low (0.744 ml X min-1 X kg-1), due to the small renal clearance (0.182 ml X min-1 X kg-1), whilst non-renal clearance (0.563 ml X min-1 X kg-1) was approximately the same as in adults. The mean apparent volume of distribution of total drug (Vz) was 0.280 l/kg. The corresponding volume of distribution of unbound drug (Vu1 + Vu2) was 1.74 l/kg, which indicates considerable extravascular drug binding. The plasma protein binding of flucloxacillin (mean 86.3%) was significantly correlated with gestational age and the bilirubin/albumin concentration ratio. Bioavailability after oral administration, when corrected for changes in terminal half-life, was 47.7%, which is only slightly lower than that reported in adults. Since the plasma concentrations after both i.v. and oral administration were well above the MIC-values generally reported for Staphylococcus aureus, and since few side-effects were observed, intravenous injection or, in selected cases, orl administration of flucloxacillin appears to be a reliable therapy for the treatment of infections due to sensitive strains of S. aureus in premature newborn infants.

Delayed inactivation of Citrobacter freundii cephalosporinase by 6 beta-[3-(2-chlorophenyl)-5-methyl-4-isoxazolyl]penicillin sulfone

When Citrobacter freundii cephalosporinase was incubated with 6 beta-[3-(2-chlorophenyl)-5-methyl-4-isoxazolyl]penicillin sulfone (cloxacillin sulfone) in phosphate buffer, the enzyme was suddenly inactivated just after the completion of enzymatic degradation of the cloxacillin sulfone. Such delayed inactivation was due to a secondary inhibitor formed from cloxacillin sulfone during the incubation period. The inactivation was delayed due to the protection of the enzyme by cloxacillin sulfone from the attack of the secondary inhibitor. Phosphate anions were essential for the formation of the secondary inhibitor. However, once the secondary inhibitor was formed, the inactivation occurred in the absence of phosphate anions although the degree of the inactivation depended on the length of the preincubation period with phosphate anions. The main species (more than 80%) of the inactivated enzyme was detected as a single protein band with a slightly lower pI value than that of the native enzyme on isoelectric focusing on a plate.

Extravascular penetration of highly protein-bound flucloxacillin

The pharmacokinetics of intravenously administered flucloxacillin (2.0 g to five volunteers) are described. The passage of flucloxacillin to peripheral lymph and suction skin blisters was monitored. This drug was selected because the high serum protein binding of 96% offered a particularly good opportunity for the study of the impact on tissue penetration. Flucloxacillin was assayed by high-pressure liquid chromatography, and pharmacokinetics were assayed by computerized curve fitting to accepted models. Penetration of flucloxacillin to extravascular foci was rapid. After 30 min the drug concentrations were 0.5 +/- 0.3 microgram/ml in lymph and 0.9 +/- 0.7 microgram/ml in blister fluid. The peak concentration was 11.7 +/- 5.6 micrograms/ml in lymph and 4.6 +/- 1.4 micrograms/ml in blister fluid. Concentrations in urine were above 111 +/- 50 micrograms/ml throughout the 8-h monitoring period, and urinary recovery was 60.4%. The half-life was 2.1 +/- 0.9 h in serum, 1.4 +/- 0.6 h in lymph, and 11.0 +/- 4.1 h in blister fluid. The differences in half-life were significant (P less than 0.05) between serum and blister fluid but not between lymph and serum. Penetration, as represented by the mean ratios of areas under the curve, was 19.7 +/- 8.1% to lymph and 38.2 +/- 11.7% to blister fluid. The flucloxacillin distribution volume during the phase of elimination was 36.4 +/- 16.0 liters and the total body clearance was 12.9 +/- 5.5 liters. Flucloxacillin showed good tissue penetration, considering its very high serum protein binding. High flucloxacillin levels in lymph and blister fluid were explained in part by drug affinity to extravascular albumin. The major impacts of high protein binding are (i) slightly slower passage into extravascular sites, (ii) slightly later peak concentration, and (iii) levels in extravascular fluid that are persistently below those in serum.

Antibiotic prophylaxis in pacemaker surgery: a prospective double blind trial with systemic administration of antibiotic versus placebo at implantation of cardiac pacemakers

In a double blind clinical trial, 106 consecutive patients scheduled for pacemaker implantation were randomly assigned either to a systemic prophylaxis group (SPG) (to be given flucloxacillin) or to a control group who would be given a placebo (CPG). The SPG group received 2 g IV flucloxacillin 1 hour before the operation, then 1 g perorally every 8 hours for the next five days. In the CPG group, placebo infusions and tablets were given at the same schedule. There were a total of 106 patients (SPG 52, CPG 54) who met the criteria of the study. Of these, 102 patients (SPG 50, CPG 52) completed a follow-up of 7-35 months. Infection of the pacemaker system was not diagnosed in any patient in either group. Tissue fluid was drawn 24 hours postoperatively from the pacemaker pocket for culture and for determination of pocket antibiotic concentration. The mean flucloxacillin concentration of pocket fluid from 23 patients in the SPG was 7.5 micrograms/ml. The bacteriological cultures were positive in 9/32 patients in the SPG group and in 10/34 patients in the CPG group. This study suggests that antibiotic prophylaxis need not routinely be given at implantation of permanent pacemaker systems.

[Clinical evaluation of flucloxacillin in the treatment of serious staphylococcal infections in children]

A total of twenty-nine children were admitted to the paediatric unit with confirmed or presumed staphylococcal infection and subsequently treated with the narrow spectrum antibiotic--flucloxacillin. Despite the gravity of their condition all but two patients made a satisfactory recovery. There were no side-effects associated with this treatment.