Biomedical subjects
Publications and source records attributed to R Lüthy.
This paper describes the standardized Kirby-Bauer disc method for the determination of antibacterial susceptibility, also including choice of antimicrobials, interpretation of results, problems with particular bacteria, and quality control. Only a meticulous adherence to the details of the method will guarantee reliable results.
Antibiotic prophylaxis for gynecologic and obstetric surgery is reviewed. Numerous clinical studies conducted under controlled conditions have established and confirmed the beneficial effects of short term (preferentially single-dose) perioperative antibiotic prophylaxis for various procedures. Cephalosporins, particularly of the first generation, have been used extensively despite the fact that their antimicrobial spectrum does not include all pathogens recovered from postsurgical infections in gynecology. Perioperative antibiotic prophylaxis is effective in reducing the incidence of infection-related morbidity and mortality of vaginal hysterectomy, especially in premenopausal women. This protective effect is less pronounced for abdominal hysterectomy. The incidence of postoperative infections at a particular hospital should be used as guideline as to whether antibiotic prophylaxis will be beneficial or not for these patients. The same applies to C-sections, for which antibiotic prophylaxis should be administered to high risk patients only, such as secondary C-section or patients with severe underlying diseases. The optimal timing appears to be after cord clamping, which prevents transfer of the antibiotic to the newborn.
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A 48-year-old homosexual with contacts in different countries, including Haiti, presented with multiple pigmented or bluish nodules on both lower legs and upper arms. He had a history of secondary syphilis, hepatitis B and herpes zoster ophthalmicus. Biopsies of the skin tumors revealed a typical Kaposi's sarcoma of low grade malignancy. The endothelial origin of the tumor was indicated by the presence of specific endothelial organelles (Weibel-Palade bodies) in the cytoplasma of the tumor cells. Erythrocyte phagocytosis was found in tumor cells within and without the vascular channels. Laboratory tests were compatible with the clinical diagnosis of an acquired immune deficiency syndrome (AIDS) with a helper: suppressor T-lymphocyte ratio of 0.28 and a cutaneous anergy. In the course of the illness tumors of the stomach and duodenum were detected. Histology showed a malignant non-Hodgkin lymphoma of high grade malignancy. Within weeks the patient died in a cachectic state. Autopsy revealed a Kaposi's sarcoma of the skin with metastases in the stomach and a wide-spread malignant lymphoma in the gastrointestinal tract, in several visceral organs and in many lymph nodes.
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The results of an 11-month pilot study of surveillance of nosocomial infections are reported. Prospective surveillance was performed by daily examination of the microbiology reports and daily visits by the infection control nurse to the ward for the review of charts and Kardex of all patients for detection of "infection clues". Work sheets were used to collect all data during the daily rounds. Infection rates were calculated by dividing the the total number of hospital-acquired infections by the total number of discharges during the surveillance period. Active surveillance was performed for 6 months in the surgical intensive care unit (SCIU), 5 months in the surgical ward (SW) and 9 months in the medical ward (MW). Of 1527 patients discharged from these wards, nosocomial infections developed in 158 patients (10.4%). The overall infection rate was 14% (214 nosocomial infections). The infection rate varied greatly from ward to ward due to different patient populations, invasive procedures and severity of underlying diseases. Incidence infection rates were 42.5% for the SICU, 19.6% for the SW and 4.1% for the MW. The major sites affected were surgical wounds (42%), urinary tract (23%), respiratory tract (19%) and bloodstream (8%). The major etiologic agents associated with these nosocomial infections were E. coli, Pseudomonas aeruginosa, enterococci and Staphylococcus aureus. Conclusions drawn from the results of surveillance are discussed. The major benefits of an effective surveillance program for nosocomial infections are (a) estimates of the endemic levels of nosocomial infection, (b) identification of the nosocomial pathogens commonly encountered within a given institution, (c) identification of risk factors and (d) prompt recognition of epidemics. These data provide the necessary basis for an effective infection control program.
Ceftazidime, a new cephalosporin, is characterized by very good in-vitro action against P. aeruginosa. Nonetheless, clinical and (or) microbiological failure occurred in four patients with severe P. aeruginosa infections being treated with ceftazidime. Main cause infections being treated with ceftazidime. Main cause of the discrepancy between in-vitro and in-vivo results during treatment of three patients was a rapid drop in bacterial sensitivity. Superinfection with resistant microorganisms was excluded by the identity of the isolated bacteria in the different epidemiological markers before and during treatment. This rise in resistance was also demonstrated in-vitro by culturing clinically isolated material in ceftazidime-containing media: a 16-fold decrease in sensitivity was demonstrated within three subcultures. Increased beta-lactamase activity of the resistant strains makes it likely that enzymatic inactivation was part of the resistance mechanism. Good inducibility of beta-lactamases and absent resistance transfer argue for chromosomal localisation of the resistance. Because of the development of resistance, severe infections caused by P. aeruginosa should not be treated by ceftazidime alone. In order early to discover the development of resistance, microbiological samples should be taken periodically and examined for their sensitivity.
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Serum kinetics of amikacin were investigated in 17 severely ill patients. During both the first and last dose intervals of therapy, the serum concentration time course of every patient was documented by 17 blood samples. Six of the patients had moderate to severe renal insufficiency (serum creatinine greater than 1.5 mg/100 ml). In this group of patients, a pronounced rise in serum half-life of amikacin was observed, increasing from a mean of 11.2 to 21.5 h for the first and last interval, respectively. In contrast, mean half-life remained stable in the group of 11 patients with normal renal function. No change in mean serum creatinine occurred in either group, when data from the beginning and the end of therapy were compared. Therefore, the increase of amikacin half-life is apparently not due to a reduction of the glomerular filtration rate, but rather to a decrease of the ratio of amikacin to creatinine clearance. Indeed, a significant reduction of this ratio could be shown in the seven patients in which 24-h creatinine clearance was determined during the first and last day of therapy. This phenomenon is discussed in the context of aminoglycoside accumulation in deep compartments. We conclude that the daily dose of amikacin has to be reduced during therapy in patients with impaired, but stable, renal function.
The pharmacokinetics of cephalothin sodium were studied in seven patients with chronic renal failure undergoing continuous ambulatory peritoneal dialysis. 100 mg of cephalothin per liter dialyzate were administered intraperitoneally during nine dialysis cycles with 2 liters of dialysis fluid per cycle. Serum levels of the antibiotic, measured microbiologically during the first, fifth and ninth dwell time, revealed peak values of 3.5 +/- 1.7 mg/l, 5.6 +/- 2.2 mg/l and 5.3 +/- 2.5 mg/l, respectively. The mean concentration in the dialysis outflow was 23.6 +/- 15.6 mg/l (range: 2.0-78.7 mg/l). Intraperitoneally administered cephalothin is well tolerated. Serum levels exceeded the minimal inhibitory concentrations of most gram positive bacteria causing peritonitis in these patients.
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To gain information on antibiotics usage in the daily practice of ENT specialists in the Zürich area, 64 questionnaires were distributed at the beginning of 1980. Approximately half the questionnaires were returned. The results of antibiotics usage in common ENT infections are summarized and their bacteriological spectrum is discussed in the light of the literature. Finally, the spectrum of activity and daily cost of various antibiotics are discussed and an appropriate antibiotic therapy is recommended.