Tom Bergan

Survey of Heat-Stable, Major Somatic Antigens of Pseudomonas aeruginosa†

A survey of all serogrouping schemata for Pseudomonas aeruginosa was conducted in order to identify all of the heat-stable major somatic antigens. In addition to the 12 antigens described in the schema of Habs (Z. Hyg. 144:218-228, 1957), five antigens from other schemata were found to be distinct. A grouping schema comprising 17 groups based on these antigens is proposed as the international serogrouping schema for P. aeruginosa. This schema is proposed as the backbone for future serotyping schemata that may include minor heat-stable antigens and heat-labile antigens. Several modifications of the schema are discussed. Variations of the schema can be adopted by individual laboratories without much confusion if the basic designations of the 17 antigens are retained.

Pharmacokinetics of ciprofloxacin

SummaryThe fluorination of piperazinyl substituted quinolones has led to an interesting development of a series of new broad spectrum antibacterial agents that may be administered orally as well as parenterally and are well tolerated. Norfloxacin was an early compound, later followed by ciprofloxacin, enoxacin, ofloxacin and pefloxacin. In this overview the emphasis will be on the most extensively studied compound including comparisons, where data are available, with norfloxacin and ofloxacin. Enoxacin and pefloxacin will be omitted due to their pattern of side effects, which at present curtail their therapeutic use. More recent substances such as fleroxacin and defloxacin have not been sufficiently investigated to be considered in this context.ZusammenfassungDie Fluorierung von Piperazin-substituierten Chinolonen hat zur Entwicklung einer interessanten Serie neuer Breitspektrum-Antibiotika geführt, die oral und parenteral verabreicht werden können und gut vertragen werden. Norfloxacin wurde bereits früh entwickelt, es folgten Ciprofloxacin, Enoxacin, Ofloxacin und Pefloxacin. In der vorliegenden Übersicht wird die am umfangreichsten untersuchte Verbindung am stärksten berücksichtigt und es werden, soweit verfügbar, Daten von Norfloxacin und Ofloxacin zum Vergleich herangezogen. Wegen ihrer Nebenwirkungs-Profile, die derzeit ihre therapeutische Anwendung einschränken, werden Enoxacin und Pefloxacin übergangen. Für Substanzen jüngeren Datums, wie Fleroxacin und Defloxacin liegen für eine Diskussion in diesem Rahmen noch nicht genügend Untersuchungen vor.

Pharmacokinetic properties of the cephalosporins.

SummaryMost cephalosporins can only be administered parenterally. Among agents that are absorbed from the gastrointestinal tract, those with bioavailabilities of 85 to 90% include cefroxadine, Cefadroxil, cefsumide, cephalexin, cephradine, cephacetrile, and cefazaflur. Most cephalosporins are eliminated rapidly, with serum half lives (t1/2s) of 1 to 2 hours. Exceptions are cefonicid with a t1/2of 4.4 hours, cefpiramide with a t1/2of 5.0 hours, and cefotetan with a t1/2of 3.5 hours. The longest half life is shown by ceftriaxone with a t1/2of 8.5 hours. Cephalosporins are eliminated mostly by the kidneys, some with a substantial contribution from active tubular secretion, which is blocked by probenecid. The degree of metabolism varies. Only a few cephalosporins have a high biliary elimination. For example, with intravenously administered cefoperazone, about 70% appears in bile. High biliary elimination is also observed with cefmenoxime, ceftriaxone, cefbuperazone, and latamoxef (moxalactam). Because these are not appreciably absorbed from the gastrointestinal tract, the consequence is high intraintestinal concentrations of the drugs and a marked ensuing depression of the normal microflora with simultaneous emergence of resistant bacteria. The untoward ecological impact may even lead to Clostridium difficile-associated enterocolitis.

Chapter IV Serological Characterization of Pseudomonas aeruginosa

Publisher Summary This chapter reviews methodology and application of serology and shows the way the serotyping system of Habs can be constructed to recognize the cross-reactions among serogroups. Most common pseudomonas infections are of the urinary tract, respiratory tract—particularly in the aged, in premature babies, and in tracheostomized patients—and burn wounds. Patients with infections to a considerable extent maintain the nosocomial situation because they constitute reservoirs from which spread may occur to the environment. It is also important that there are healthy carriers of pseudomonas. Spreading occurs easily. Because of extensive resistance to antibiotics, pseudomonas infections may be difficult to eradicate and have serious consequences. In this situation, it is necessary to identify the sources and follow the routes of transmission. As tools to this end epidemiological typing methods have been developed: pyocine typing, bacteriophage typing, and serological typing. Serological characterization is necessary for attempts of active or passive immunization against pseudomonas in animals and man.

Pharmacokinetics of ciprofloxacin and effect of repeated dosage on salivary and fecal microflora.

The pharmacokinetics of ciprofloxacin was studied in 12 volunteers during a 5-day course of 500 mg of ciprofloxacin given orally twice a day. The effects on the microflora of saliva and feces were also examined. Serum and urine samples were assayed for ciprofloxacin microbiologically, and the salivary and fecal microflora were examined quantitatively after processing onto a series of selective media. Fecal samples were also investigated for the presence of Clostridium difficile and its cytotoxin. The MICs for new colonizing bacteria were examined in the salivary and fecal samples. There was no accumulation during the course of 5 days with peak serum concentrations identical (2.8 and 2.3 mg/liter) after the first and final doses, and the areas under the serum curves were similar (9.6 mg/liter). The serum half-life was 2.5 h on both days. The changes in the salivary flora were minor and affected only the neisseriae. In the fecal flora, the numbers of enterobacteria and enterococci decreased markedly, whereas the changes in anaerobic flora (anaerobic cocci, fusobacteria, and bacteroids) were not so pronounced. However, 14 days after the drug was discontinued, the salivary and fecal flora were normalized in all respects. No new colonization of ciprofloxacin-resistant bacteria for which MICs were above 1.0 mg/liter was observed. C. difficile or its cytotoxin was not detected.

Transintestinal elimination of ciprofloxacin

This study identified the routes of elimination of ciprofloxacin in two groups of five subjects each: one of healthy volunteers; the other of patients with severe renal failure having mean creatinine clearance of 12 ml/min (range, 8-16 ml/min). Each subject received one dose of 200 mg ciprofloxacin infused intravenously (IV) over 30 min. In an effort to recover the total drug administered, all urine and feces were collected for 7 days following dosing. Blood samples were drawn at set intervals. Serum, urine, and feces were assayed for ciprofloxacin and metabolites by high-pressure liquid chromatography. The ciprofloxacin elimination half-life was 3.9 +/- 0.4 hr in the healthy volunteers and 11.2 +/- 2.5 hr in the patients with severe renal failure. The total 7-day recovery of ciprofloxacin and its metabolites in urine and feces ranged from 74.0% to 114.7% of the dose (mean, 96.3 +/- 14.1%) in normal subjects and from 48.5% to 109.1% (mean, 88.1 +/- 20.9%) in patients. The dose of ciprofloxacin recovered in urine was 65.3 +/- 10.7% in healthy subjects and 19.0 +/- 15.9% in impaired patients (reduction factor, 3.4). In contrast, the dose recovered in feces was 11.4 +/- 2.6% in the group of normal subjects and 37.2 +/- 12.5% in the group of patients with impaired renal function in a 3.3-fold increase.(ABSTRACT TRUNCATED AT 250 WORDS)

Pharmacokinetics of Bacampicillin Compared with Those of Ampicillin, Pivampicillin, and Amoxycillin

Bacampicillin, a new oral prodrug which in vivo is rapidly transformed to ampicillin, was compared with ampicillin, pivampicillin, and amoxycillin in a randomized cross-over study on 11 healthy volunteers. All drugs were given in oral doses equimolar to 400 mg of bacampicillin (800 μmol). The mean of the individual peak concentrations in serum was 8.3 μg/ml for bacampicillin, 7.1 μg/ml for pivampicillin, 7.7 μg/ml for amoxycillin, and 3.7 μg/ml for ampicillin. Furthermore, bacampicillin had a higher absorption rate than all the other drugs, although there were statistically significant differences only versus ampicillin. The peak serum levels of the individual subjects were more dispersed with ampicillin and amoxycillin, suggesting a more uniform absorption of bacampicillin and pivampicillin. The relative bioavailability of bacampicillin and pivampicillin was comparable, whereas ampicillin was only 2/3 that of the others.

Vaginal disinfection with chlorhexidine during childbirth.

The purpose of this study was to determine whether chlorhexidine vaginal douching, applied by a squeeze bottle intra partum, reduced mother-to-child transmission of vaginal microorganisms including Streptococcus agalactiae (streptococcus serogroup B = GBS) and hence infectious morbidity in both mother and child. A prospective controlled study was conducted on pairs of mothers and their offspring. During the first 4 months (reference phase), the vaginal flora of women in labour was recorded and the newborns monitored. During the next 5 months (intervention phase), a trial of randomized, blinded placebo controlled douching with either 0.2% chlorhexidine or sterile saline was performed on 1130 women in vaginal labour. During childbirth, bacteria were isolated from 78% of the women. Vertical transmission of microbes occurred in 43% of the reference deliveries. In the double blind study, vaginal douching with chlorhexidine significantly reduced the vertical transmission rate from 35% (saline) to 18% (chlorhexidine), (P < 0.000 1, 95% confidence interval 0.12-0.22). The lower rate of bacteria isolated from the latter group was accompanied by a significantly reduced early infectious morbidity in the neonates (P < 0.05, 95% confidence interval 0.00-0.06). This finding was particularly pronounced in Str. agalactiae infections (P < 0.0 1). In the early postpartum period, fever in the mothers was significantly lower in the patients offered vaginal disinfection, a reduction from 7.2% in those douched using saline compared with 3.3% in those disinfected using chlorhexidine (P < 0.05, 95% confidence interval 0.01-0.06). A parallel lower occurrence of urinary tract infections was also observed, 6.2% in the saline group as compared with 3.4% in the chlorhexidine group (P < 0.01, 95% confidence p interval 0.00-0.05). This prospective controlled trial demonstrated that vaginal douching with 0.2% chlorhexidine during labour can significantly reduce both maternal and early neonatal infectious morbidity. The squeeze bottle procedure was simple, quick, and well tolerated. The beneficial effect may be ascribed both to mechanical cleansing by liquid flow and to the disinfective action of chlorhexidine.

Effect of Norfloxacin on Human Oropharyngeal and Colonic Microflora and Multiple-dose Pharmacokinetics

10 healthy volunteers received 200 mg norfloxacin orally every 12 h for 7 days. Saliva, throat and faecal specimens were collected days 0, 3, 5, 7, 14 and 21 to study the effect of norfloxacin on the normal microflora. The concentrations of norfloxacin in serum, urine, saliva and faeces were determined by a microbiological method and all samples except faeces were also assayed by high-pressure liquid chromatography (HPLC). The pharmacokinetics of norfloxacin were studied on day 3. The mean peak serum concentration (+/- SD) attained after 0.75-1.0 h was 0.75 +/- 0.15 mg/l measured by HPLC, and the mean terminal serum half-life was 4.2 +/- 0.6 h. The mean cumulative urinary elimination was 29% during 12 h after dosing. There was no significant difference between values obtained by microbiological assay and by HPLC. The saliva concentration was approximately 30% of the serum levels 1.0-1.5 h after administration. No accumulation in faeces was found during the administration period, and mean concentrations were 940 mg/kg. The changes in the oropharyngeal flora were minor and only branhamella were affected. In the colonic flora, the number of enterobacteria was strongly depressed while the anaerobic microflora was only slightly affected. Two weeks after the administration period, both the oropharyngeal and colonic microflora had returned to normal.

Pharmacokinetics of ciprofloxacin after intravenous and increasing oral doses

The pharmacokinetics of ciprofloxacin were evaluated after increasing single oral doses of 100, 250, 500 and 1000 mg, and an intravenous dose of 100 mg given to each of 12 healthy volunteers (6 females and 6 males). Concentrations in serum and urine were determined by microbiological assay. The rise in peak serum concentrations and the values of the total area under the serum concentration curve were proportional to the increase in the oral doses. As the oral dose increased a slight increase was observed in the apparent time lag before absorption from 0.34 h after 100 mg to 0.53 h after 1000 mg. The serum half-life after the intravenous dose was 3.2 h. After the oral doses shorter apparent half-life values were observed. The intravenous dose showed an elimination phase distribution volume of 2.76 l/kg and total body clearance of 40.7 l/h. The total urinary excretion was 42.2±15.6% of the dose after the intravenous dose; the figure was lower after the oral doses. The bioavailability of the 100 mg oral dose was 83.7% as calculated from the value of the total area under the serum curve after the same oral and intravenous dose in all 12 subjects. Ciprofloxacin thus demonstrates normal linear pharmacokinetics, the rise in serum concentrations being proportional to the dose.