A system dynamics-based scenario analysis of residential solid waste management in Kisumu, Kenya

The problem of solid waste management presents an issue of increasing importance in many low-income settings, including the progressively urbanised context of Kenya. Kisumu County is one such setting with an estimated 500 t of waste generated per day and with less than half of it regularly collected. The open burning and natural decay of solid waste is an important source of greenhouse gas (GHG) emissions and atmospheric pollutants with adverse health consequences. In this paper, we use system dynamics modelling to investigate the expected impact on GHG and PM_2.5 emissions of (i) a waste-to-biogas initiative and (ii) a regulatory ban on the open burning of waste in landfill. We use life tables to estimate the impact on mortality of the reduction in PM_2.5 exposure. Our results indicate that combining these two interventions can generate over 1.1 million tonnes of cumulative savings in GHG emissions by 2035, of which the largest contribution (42%) results from the biogas produced replacing unclean fuels in household cooking. Combining the two interventions is expected to reduce PM_2.5 emissions from the waste and residential sectors by over 30% compared to our baseline scenario by 2035, resulting in at least around 1150 cumulative life years saved over 2021–2035. The contribution and novelty of this study lies in the quantification of a potential waste-to-biogas scenario and its environmental and health impact in Kisumu for the first time.

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We present a system dynamics study of solid waste management in Kisumu, Kenya.

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Scenarios involve a waste-to-biogas initiative and a ban on open burning in landfill.

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Combined scenario generates 1.1m tonnes cumulative GHG savings by 2035.

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Largest contribution (42%) is from biogas substituting traditional cooking fuels.

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Combined scenario may save 1,150 cumulative life years by 2035, plus ~220 more p.a.

[In-vitro activity of enoxacin: a multicenter study]

The in vitro activity of enoxacin was tested in 14 German microbiological centers shortly after the introduction of the drug in Germany. 2748 unselected clinical isolates including 15 bacterial species were analysed using microtiter plates. The MIC90-values were as follows: Staphylococcus aureus 4 mg/l, Enterococcus faecalis 16 mg/l, Enterobacteriaceae 0.5 mg/l, Pseudomonas aeruginosa 8 mg/l. There is good correlation between these results and those of former investigations. It is known that quinolones are only moderately active against enterococci. 8.5% of S. aureus, and 1.4% of Enterobacteriaceae were found to be resistant (MIC greater than 4 mg/l). As to P. aeruginosa, the study revealed that despite a generally low rate of resistance in specific clinical settings, specific problems can arise: in one institution, the MIC90 of P. aeruginosa was 32 mg/l, with a resistance rate of 56.1% (n = 57). In the other centers the MIC90 was 2 mg/l and the resistance rate 5.0% (n = 302). In the first center, many of the isolates were from paraplegic patients or patients with cystic fibrosis pretreated with quinolones. This study will be repeated in two years' time in order to determine an eventual change in resistance.

Antibiotic resistance in intensive care unit areas

The incidence of nosocomial infections and antimicrobial resistance rates of nosocomial pathogens vary considerably among countries and even among intensive care units (ICUs) within one hospital. Such differences might be partly due to the selection pressure exerted by certain antibiotics, since intensive care patients are given more antimicrobials than any other group of patients. We therefore compared resistance rates of four important nosocomial pathogens (Staphylococcus aureus, E. coli, Klebsiella pneumoniae, Pseudomonas aeruginosa) isolated from patients in general wards and ICUs. There were few trends toward higher resistance of ICU isolates, and most differences were found with Klebsiella pneumoniae. We also tried to relate antibiotic use in ICUs and frequency of antibiotic resistance of five selected nosocomial pathogens. The ampicillin and cephalosporin resistance of E. coli and Klebsiella pneumoniae arose along with an increase in usage of both drugs. Decreasing prescription of cotrimoxazole was not reflected by decrease in resistance of Staphylococcus aureus and Staphylococcus epidermidis. Increasing prescriptions of tetracyclines were followed by an increasing resistance of E. coli, but not of Staphylococci. The oxacillin resistance of Staphylococcus epidermidis almost paralleled the consumption, the opposite was true for Staphylococcus aureus. There seemed to be a rather close relationship between the incidence of resistant Staphylococcus aureus, Staphylococcus epidermidis and Pseudomonas aeruginosa strains and the quantities of gentamicin, tobramycin and azlocillin prescribed. The increase or decrease of prescriptions of certain antimicrobials increased or decreased their resistance rate to the respective drugs of only certain bacterial strains in one ICU, but not in the other. The findings in our hospital cannot necessarily be applied to other hospitals.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibiotic prophylaxis in gynecology: cefoxitin concentrations in serum, myometrium, endometrium and salpinges

Thirty-six patients received an intravenous bolus injection of 2 g cefoxitin over 5 min at various times before abdominal or vaginal hysterectomy. Cefoxitin levels in myometrium and salpinges were substantially higher than those in endometrium and almost as high as those in serum during the first two hours following the i. v. administration of the drug. Tissue concentrations of 8 micrograms/g could be maintained for two hours. The cefoxitin tissue concentrations attained in myometrium, endometrium and salpinges justify controlled prospective clinical studies on the prevention of postoperative wound infections with this antibiotic.

[Nosocomial infections in rooming-in system: results of a two-year study]

Nosocomial infections of 1356 mothers and their newborn have been analyzed and compared in three different regimens for postnatal care of newborn (rooming-in service, mixed service and central newborn nursery). The average nosocomial infection rate of mothers was significantly lower in the rooming-in service as compared to the newborn nursery. Most common nosocomial infections of mothers were urinary tract infections, endometritis, wound infection, enteritis and mastitis; in newborn enteritis, oral candida infections, panaritium, conjunctivitis and staphylococcus skin infections. Staphylococcal infection of newborn were higher in the newborn nursery as compared to the rooming-in service. Epidermic nosocomial infections (e.g. enteritis, candida infections) occurred more often in the newborn nursery as compared to the mixed system and rooming-in service. There was an increased risk of cross infections from mothers with wound infection, endometritis and mastitis to their children.

[Control of serum levels of tobramycin and amikacin during clinical routine treatment conditions (author's transl)]

576 serum levels at peak and before the next dosage (end level) were determined during clinical treatment conditions using radioimmunoassay in 131 patients treated with tobramycin or amikacin because of life-threatening infections. Only 42.8% of tobramycin serum peak levels were within the therapeutic range. 3.6% were potentially toxic, however, 53.6% were in a subtherapeutic range. After amikacin administration only 25% of serum peak levels were in a subtherapeutic range. 54.2% were therapeutic and 20.8% were potentially toxic. The main reason for increased peak and end serum levels was diminished renal function. Infusion treatment with more than 3 1/24 hrs lowered serum peak levels of tobramycin by 38% and of amikacin by 31%. Single doses of 80 mg of tobramycin lead to subtherapeutic concentrations too frequently, whereas single doses of 500 mg of amikacin too frequently lead to potentially toxic serum levels. Control of serum levels during aminoglycoside treatment is recommended particularly in patients at risk with life-threatening infections.

[Nosocomial infections in an operative intensive care unit. Results of a four year prospective study (author's transl)]

The average nosocomial infection rate during a four year prospective study period was found to be 26.4%. Most common hospital acquired infections were urinary tract infections, pneumonia, septicemia, infections of the skin and wound infections. The most common isolated organisms were: Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Enterococci and Klebsiella pneumoniae. Infection control programs reduced the infection rate by 32%.

[Campylobacteriosis in humans caused by subspecies intestinalis and fetus. Six new diseases (author's transl)]

The subspecies intestinalis and fetus of Campylobacter fetus are opportunistic pathogens in humans. So far, some 200 types of disease due to these pathogens have been reported from all over the world, and six new diseases are briefly described in this paper. The most frequent disease is sepsis, followed by meningitis. While ticarcillin, erythromycin, clindamycin and tetracycline are the antibiotics which show activity against these species, a large degree of resistance is seen against cephalothin, cefazolin, cefuroxime, cefoxitin and cefotaxime. There is a moderate degree of sensitivity to gentamicin. The epidemiology of the disease is not clear, and about twice as many men are affected as women. Subspecies intestinalis was isolated in 95% of all diseases. Antibodies to Campylobacter fetus were detected in 3.9% of the population.

[Experimental and clinical investigations on reapplicability of resterilized intravascular catheters (author's transl)]

Catheters for cardiovascular and other angiographic investigations can be resterilized by ethyl-oxide. The procedure of sterilisation has to be controled permanently. Reapplicability of catheters has become quite common because of the high price of new catheters. In spite of optimal resterilisation and permanent controll some patients still get fever attacks, because endotoxins cannot be eliminated by this method.

Combination effect of piperacillin with four aminoglycosides on nonfermenting gram-negative bacteria

The in vitro efficacy of piperacillin in combination with gentamicin, tobramycin, amikacin and netilmicin against 57 nonfermenting gram-negative bacterial strains was compared by use of the checkerboard agar dilution technique. On average 34% of all nonfermenting strains were inhibited by additive, 13% by synergistic piperacillin-amino-glycoside combinations. Great variation occurred between the different bacterial species. Piperacillin-aminoglycoside combinations were most active on Pseudomonas aeruginosa and least potent on Pseudomonas cepacia. Piperacillin was highly active against P. aeruginosa, P. cepacia, Pseudomonas fluorescens-putida and Acinetobacter species.

Ticarcillin concentrations in serum, muscle, and fat after a single intravenous injection

Ticarcillin concentrations in serum, muscle, and fat were determined simultaneously in 23 patients after the intravenous injection of a single dose of 5 g. The mean concentrations of ticarcillin in serum, muscle, and fat were, respectively, 185 microgram/ml, 18 microgram/g, and 32 microgram/g at 1.0 to 1.5 h after the injections, declining to levels of 11 microgram/ml, 2 microgram/g at 6 to 7 h after the injections. There was no significant difference between the serum tissue ratios at these time periods.

[Surface decontamination in the control of hospital infections: comparison of different methods (author's transl)]

Using a 1% aldehyde disinfectant the bacterial count was reduced by 84% by scrubbing the floor, by 60% with a wet mop and by 50% with a dry mop. However, two hours after floor disinfection the bacterial count was nearly back to pretreatment when walked on again. Disinfectant mats did not decrease bacterial count on the surface behind them. Plastic overshoes did not influence floor contamination. There was no significant difference regarding the infection rate, in an intensive care unit during a six-month period, between routine floor disinfection and cleaning without disinfectant. It is possible that by doing without routine floor disinfection something like 20 million DM can be saved per year. The World Health Organisation also recommends floor disinfection only immediately after contamination of the floor by infectious secretions.

[Spread of Yersinia enterocolitica infection within a hospital (author's transl)]

Infections linked in time and space with Yersinia enterocolitica (serovar 0 : 9, biotype 2, lysotype X3) were observed in 6 cases within one university hospital. After a hospital epidemic in Finland in 1973 (involving 7 persons) this is the 2nd such observation. The spread was demonstrated in two areas. The probable source of infection of one patient group (n = 3) was a 48-year-old dialysis patient admitted with a febrile condition without enteritic symptoms. Pathogens could be demonstrated in his faeces by direct culture, in two contact persons cultivation was possible only with cold enrichment. Blood cultures of the first patient were negative. At about the same time 3 further infections with Yersinia enterocolitica of the same characteristics were observed in hospital personnel from different units. Frequent exchange of staff and patients among affected wards increases likelihood of cross-infection. A dialysis nurse with Yersinia arthritis was the possible link between patients and personnel. Transference of infection from one person to another can be assumed in the above cases.

In vitro efficacy of Bay k 4999, a new ureido-penicillin, in combination with aminoglycosides against Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae and Proteus strains

The in vitro effects of Bay k 4999 in combination with gentamicin, tobramycin, amikacin sisomicin and netilmicin in bacteriostatic (MIC) and bactericidal (MBC) concentrations were compared using the checkerboard dilution technique against 20 different strains of Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae and indole-positive-negative Proteus species. On average 63% of Bay k 4999-aminoglycoside (AG) combinations inhibited Pseudomonas, Proteus and Klebsiella strains additively and/or synergistically in bacteriostatic as well as in bactericidal concentrations as compared to only 14% additive or synergistic activity on E. coli. 35% of the combinations tested proved to be synergistic in K. pneumoniae, 20% in Proteus, 13% in Pseudomonas, but only 5% in E. coli. No significant differences between various Bay k 4999-AG combination effects could be demonstrated.

Surveillance, prevention and control of hospital-acquired infections. III. Nosocomial infections as cause of death: retrospective analysis of 1000 autopsy reports

One thousand post-mortem reports were analysed retrospectively to see whether the patient had had a nosocomial or community-acquired infection and whether this led directly to or contributed to the patient's death. In 7.4% of all autopsies nosocomial infection was the direct cause of death. In 6.3% of the patients, nosocomial infection was a contributory factor leading to death. The most common hospital infections were pneumonia, septicaemia, peritonitis, meningitis, and hepatitis B. Most infections which led to or contributed to death were acquired in surgical wards. Patients with nosocomial infections, however, were more endangered by factors predisposing to infections (1.8 factors per patient) than patients without nosocomial infections (0.67 factors per patient). Sixty-three patients acquired an infection outside the hospital; in 70% of these patients, the infection was the main or contributory cause of death.

[Azlocillin and mezlocillin: two new semisynthetic acylureido-penicillins (author's transl)]

The pharmacokinetic parameters of two new ureido-penicillins (azlocillin and mezlocillin) were determined in 12 healthy subjects after a half-hour continuous infusion of 5,000 mg. The agar diffusion test (test strain Bacillus subtilis ATCC 6633) was used for the microbiological assays. The mean azlocillin serum concentration after the half-hour infusion was 431.0 +/- 75.0 microgram/ml; after eight hours it had fallen to a mean value of 4.7 +/- 2.6 microngram/ml. The mean elimination half-life was 77.5 +/- 10.4 minutes, and the relative distribution volume was 19.4 +/- 1.9% of the bodyweight. At the end of the infusion, mezlocillin showed a mean serum concentration of 426.0 +/- 61.0 microgram/ml and after eight hours an average of 1.1 +/-0.9 microgram/ml; the half-life was shorter (56.9 +/- 9.9 minutes) and the distribution volume lower (14.8 +/- 3.1%) than that of azlocillin. The renal clearance values measured in three subjects during a four-hour continuous infusion were: azlocillin 111.6 ml/min/1.73 m2, mezlocillin 121.5 ml/min/1.73 m2. The kinetic behaviour of the two ureido-penicillins was essentially very similar to that of ampicillin and carbenicillin, 38 patients with bronchopneumonia, cholangitis or urinary tract infections, which in some instances were severe, were treated for an average of 10 days with an average daily dosage of 3X4.0 g azlocillin or 3X5.0 g mezlocillin. 30 patients showed clinical improvement, and in 17 of these the pathogen was eliminated. These therapeutic results appear more favourable than those obtained with the newer aminoglycoside antibiotics (amikacin, sisomicin); in particular the drug was well tolerated.

[Bacterial endocarditis. Clinical picture, treatment and course in 37 patients (author's transl)]

Between March 1971 and April 1976 37 patients were seen with manifest bacterial endocarditis. The main signs were high temperature and cardiac murmurs whereas other "classical" signs such as splenomegaly, anaemia, leucocytosis, and positive anti-streptolysin titres were much less frequent. In 35 cases bacteriological proof was possible. As causative organism a total of 30 gram-positive organisms (of which 15 were Streptococcus viridans and 8 were Staphylococcus species) and 10 gram-negative bacteria (4 of which were Pseudomonas aeruginosa) could be demonstrated. Treatment was mainly with beta-lactam and/or aminoglycoside antibiotics. Use of the combination of penicillin and streptomycin or gentamicin was based on the results of in-vitro bactericidal activity. The main complications were emboli, penicillin allergies, pulmonary involvement and cardiac complications. 13 patients died; the main cause was cardiac failure which was irreversible even despite operative valve replacement during the acute infection in two cases.

[Ways to an efficient and practicable hospital hygiene from the point of view of a hospital hygienist (author's transl)]

Hospitalepidemiology means surveillance, prevention andocntrol of nosocomial infections. Trying to succeed he has to search for possiblities which are both practical as well as efficient: 1. The infection control nurse (one for 300 beds), 2. a bacteriological labor is for the epidemiologist, which is able to perform routine control on certain areas in the hospital (kitchen, sterilisation etc.), 3. encironmental examinations if necessary to find sources and for teaching purposes, 4. training of hospital personal in prevention, recognizing nosocomial infections, performing methods of desinfections etc., 5. trying to cooperate with the clinician in chemotherapy (selection of antibiotics, prophylaxis etc.), 6. to develop a programm to collect datas about nosocomial infections by a computer and to analyse those datas afterwards, 7. collaborativ work in a infection control commitee.

Pharmacokinetic and clinical studies with amikacin, a new aminoglycoside antibiotic

Pharmacokinetic parameters of amikacin were determined in 12 healthy volunteers after a 1-hr continuous intravenous infusion of 7.5 mg of the drug/kg. The serum concentration rose rapidly to a peak of 37.5 +/- 4.9 mug/ml at the termination of the infusion and declined to 1.3 +/- 0.5 mug/ml 8 hr later. The mean half-life was 114 +/- 16.7 min, and the apparent volume of distribution was 18.1% +/- 1.8% of body weight. During a 4-hr constant intravenous infusion in three subjects, amikacin was cleared from the kidney at a mean rate of 84.3 ml/min per 1.73 m2, and from the serum at a mean rate of 129.7 ml/min per 1.73 m2. Of the administered dose, 93.5% was recovered from the urine in 24 hr (81.7% during the first 6 hr). After single intramuscular injections of 5 mg/kg in 30 patients, serum levels peaked at 1 hr (21.4 +/- 5.4 mug/ml) and declined to 2.4 +/- 0.9 mug/ml by 8 hr. Of 33 patients with serious urinary or bronchopulmonary infections (usually superimposed on chronic organic pathology) treated with amikacin (10 or 15 mg/kg per day for eight to 17 days), 27 had a clinical remission, and in 15 of these patients the pathogen was eradicated.

[Pharmacokinetics and clinical experience with amikacin. A new aminoglycoside antibiotic]

The pharmacokinetic data of amikacin were determined after a 1 hr constant infusion with a dosage of 7.5 mg/kg body weight in 12 healthy test subjects. Microbiological bioassay was performed by the agar diffusion test. After the infusion, the mean amikacin serum concentration was 37.5 mug/ml and, 8 hours later, decreased to an average of 1.3 mug/ml. The biological half-life amounted to a mean of 114.2 min, the area below the concentration-time-curve was calculated to an average of 140.4 hr - mug/ml. The renal clearance of amikacin was determined during a 4 hr constant infusion in 3 test individuals; the average clearance was 84.3 ml/min - 1.73 m2. 38 patients with severe bronchopulmonary, urinary and peritoneal infections were treated with an average daily dose of 10-15 mg of amikacin per kg body weight during a mean period of 10 days. 32 patients showed clinical improvement, 17 of them with complete elimination of the pathogenic bacteria.

[Pharmacokinetics and clinical observations of sisomicin, a newly developed aminoglycoside derivative (author's transl)]

In a randomized study of 12 healthy subjects the pharmacokinetics of gentamicin, sisomicin and tobramycin were determined after a one-hour infusion of each drug (1.0 mg/kg body-weight) four weeks apart. There were no pharmacokinetic differences of therapeutic significance between the three drugs. The mean serum concentrations at the end of infusion were 3.85 mug/ml for gentamicin and 4.66 mug/ml for sisomicin, falling to 0.12 and 0.26 mug/ml, respectively, after eight hours. The biological half-life varied between 96 and 122 min and the apparent volumes of distribution corresponded closely tothe size of the extracellular space. The antibacterial effectiveness, tolerance and modes of application were studied in 24 patients, most of them with urinary infection, at a dosage of 1.0 mg per kg body-weight two to three times daily. Good clinical results were achieved in 15, satisfactory ones in three, and in 16 the causative bacteria were eradicated. Sisomicin was well tolerated, except for minor and reversible renal (2 patients), hepatic (3 patients), and hearing (1 patient) disturbances.

Lysozyme production as an aid for identification of potentially pathogenic strains of staphylococci

Lysozyme production is a frequent property of potentially pathogenic staphylococci. In the present study, 1,186 strains of human origin, 85 strains of animal origin, and 156 strains of Staphylococcus albus (epidermidis) were tested. Of 1,114 coagulase-positive strains of human and animal origin, 1,098 were lysozyme-positive (98.5%). On the other hand, of 157 coagulase-negative strains which, based on further investigations, belong to the potentially pathogenic staphylococci, all were lysozyme-positive. All of the 156 strains (100%) belonging to the species S. albus (epidermidis) were lysozyme-negative. We conclude that lysozyme production is a better index of potentially pathogenic staphylococci than the measurement of free coagulase, especially in cases of strains of animal origin. It is possible that lysozyme production allows a differentiation between pathogenic and nonpathogenic coagulase-negative staphylococci.