Cellulose acetate-based composites with antimicrobial properties from embedded molybdenum trioxide particles.

The objective of this research was to develop novel cellulose acetate (biopolymer) composite materials with an excellent antimicrobial activity by embedding molybdenum trioxide particles with unique high specific surface area. High surface area molybdenum trioxide particles were prepared from freshly precipitated molybdenum trioxide dihydrate (MoO3 ·2H2 O) and subsequent calcination at 340°C under H2 /N2 gas. Microbiological evaluation against Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa were performed applying a roll-on test and excellent antimicrobial activities were determined for composites with embedded anhydrous molybdenum trioxide with a high specific surface area. Cellulose acetate composites comprising MoO3 particles can eliminate three harmful bacteria as a result of the release of protons from the material and surface enlargement of the molybdenum trioxide particles. The findings support a proposed antimicrobial mechanism based on local acidity increase due to large specific surface areas. SIGNIFICANCE AND IMPACT OF THE STUDY: In this study, development of a novel thermoplastic bio-based composite with excellent antimicrobial surface properties is investigated. To the best of our knowledge, this is the first report to evaluate the antimicrobial properties of molybdenum trioxide embedded into a cellulose acetate as biopolymer matrix. The developed composites might step up to innovative applications used in modern medical and public environments.

Cefetamet pivoxil in the treatment of pharyngitis/tonsillitis in children and adults.

Between 15 and 35% of pharyngeal infections are attributable to Group A beta-haemolytic streptococci. Streptococcal pharyngitis is one of the most common infections in adolescents and children. A specific diagnosis of pharyngitis can be obtained only by isolating organisms in culture. The current treatment of choice for streptococcal pharyngitis/tonsillitis is a 10-day course of phenoxymethylpenicillin (penicillin V); however, unresolved problems concerning the use of penicillin include the timing of therapy, appropriate therapy for treatment failures, chronic carriers and those with frequent recurrences. In addition, failure rates of 10 to 35% have been reported with oral phenoxymethylpenicillin. Effective treatment alternatives in this indication include oral cephalosporin agents or penicillin/beta-lactamase inhibitor combinations. The oral cephalosporins offer the advantage of an improved pharmacokinetic profile, once- or twice-daily administration, a shorter (7-day) regimen, and a low incidence of adverse effects, although these advantages must be balanced against the broad spectrum of these agents (broader than is necessary) and their cost. Clinical trials conducted with cefetamet pivoxil, a new oral third generation cephalosporin, in both adults and children with pharyngitis/tonsillitis indicate that this agent offers an effective alternative for phenoxymethylpenicillin in this indication.

Prevention of catheter-related infections: the potential of a new nano-silver impregnated catheter.

Contaminated or infected catheters are a major source of nosocomial infections responsible for >40% of all episodes of nosocomial sepsis in acute-care hospitals. Antibiotics as well as surface modifications with, for example, hydrogels proved to be of little value in preventing the contamination of indwelling catheters. The even distribution of 10(12-13) activated silver nanoparticles per gram in various polymers, e.g. polyurethane and silicone, results in an excellent antimicrobial activity against a broad spectrum of organisms in vitro. Substantial reduction of incrustation of these catheters was also observed. These preliminary experimental data warrant clinical studies.

Contamination of central venous catheters in immunocompromised patients: a comparison between two different types of central venous catheters.

Catheters impregnated with silver have been proposed as a means of reducing catheter-related infection. We therefore performed a prospective randomized study to compare a new silver-impregnated central venous catheter (CVC) with a commercially available CVC in a cohort of immunocompromised patients. We studied 157 patients of whom 97 could be analysed. The median indwelling time in the study group (SC) was 10.5 days and 11 days in the control group (CC). The incidence of contamination in the SC group was 15.6 vs 24.6 in the CC group referring to 1000 catheter days. In both groups, we found 6% of catheter-related infections according to the definitions of a published scoring system. The differences between the two groups were not significant. We conclude that the SC decrease the incidence of catheter contamination and may have a positive effect on the reduction of CVC-related infections.

Epidural and pericranial abscesses complicating frontal sinusitis in a comatose child.

Most complications of sinusitis have a significant risk of severe morbidity and possibly mortality. Therefore a keen awareness of the subtle signs and symptoms of bacterial spread beyond the paranasal sinuses must be maintained. This increased awareness is especially important in mentally retarded and psychomotor handicapped children because they can develop a rapidly fatal course despite the absence of any warning signs.

Bioavailability of oral antibiotics in children with short-bowel syndrome.

Absorption of orally administered antibiotics (two aminopenicillins, cephalexin, trimethoprim-sulfa) was investigated in five children with sizeable resection of small bowel in the neonatal period. The absorption was proportional to the length of the remaining bowel and independent from the resected part of the gut. For cephalexin and trimethoprim a reduction of the absorption of 10% to 50% was observed, still resulting in therapeutic serum concentrations. The absorption of aminopenicillin was reduced approximately 10% of the usually achievable concentrations. Our data suggest that oral cephalexin and trimethoprim-sulfa can be used therapeutically in children with short-bowel syndrome. If aminopenicillin is indicated, parenteral therapy is advisable.

[Rational dosing intervals in streptococcal infections of the pharynx]. / Untersuchungen rationaler Dosierungsintervalle bei Streptokokkeninfektionen des Rachens.

Optimum therapy of streptococcal pharyngitis is still a matter of great debate. Kill kinetics of streptococci group A were investigated under the influence of fluctuating concentrations of penicillin V, ampicillin, cefalexin and erythromycin. Antibiotic concentrations in our in vitro model were adjusted to concentrations found in vivo in tonsillar tissue, penicillin V showed superior antimicrobial activity to ampicillin, cefalexin and erythromycin. Only the eight hourly administration of concentrations determined after the in vivo administration of either 100,000 IU/kg BW penicillin or 100 mg/kg BW of ampicillin or cefalexin effectively eradicated streptococci in the kinetic model. beta-lactamase forming bacteroides did not interfere with the elimination of streptococci by non beta-lactamase stable antibiotics. These data suggest that penicillin V constitutes the optimum choice of antibiotic. Efficient eradication can be achieved by the administration of a total daily dosage of 100,000 IU/kg BW at 8 hourly intervals.

Antimicrobial susceptibility pattern of Neisseria gonorrhoeae in western Austria.

From January to October 1992 24 Neisseria gonorrhoeae isolates from clinical specimens were collected at the Federal Public Health Laboratory in Innsbruck (Austria) and screened for resistance to penicillin G, erythromycin, tetracycline, spectinomycin, ceftriaxone, cefuroxime, ciprofloxacine, and silver nitrate. Patients originated from the Austrian provinces Salzburg, Tirol, and Vorarlberg, and presented with manifest gonorrhoea. Two of 24 isolates were penicillinase-producing N. gonorrhoeae. Both strains were isolated from men who had just returned from Thailand or Kenya. The isolate from Africa was also resistant to tetracycline. Five of 24 infections were acquired abroad, sex tourism being involved in four cases. The antimicrobial resistance pattern found in gonococci in western Austria revealed that topical silver nitrate and erythromycin are equally acceptable for use in prophylaxis of neonatal ophthalmia. Penicillin is still the drug of choice in the treatment of endemic infections. If gonorrhoea has been acquired abroad, especially in Asia or Africa, ceftriaxone, spectinomycin or ciprofloxazine are recommended for therapy.

[The kinetics of bacterial killing by fluctuating concentrations of antibiotics]. / Absterbekinetik von Keimen unter fluktuierenden Konzentrationen von Antibiotika.

Differences in kill kinetics and the regrowth pattern of bacteria under the influence of various antibiotics are frequently not represented by their MIC values. The area under the concentration curve represents antimicrobial activity more accurately than the peak concentration. Readministration of antibiotics should occur prior to bacterial regrowth for optimal efficacy. When administering combinations of antibiotics non-simultaneous dosing is superior to simultaneous administration.

[Selection of physiologic bacterial flora by chemotherapeutic agents]. / Selektionierung der physiologischen Keimflora durch Chemotherapeutika.

A variety of antimicrobial agents has been shown to induce alterations in the bacterial homeostasis of the human microflora. Although the role of the normal flora is still poorly understood, there is evidence that alterations in the flora have a number of important clinical consequences. The normal flora acts as a natural defence against colonization or infection with pathogens. In addition, the altered flora may assume importance as a reservoir of potential pathogens. Thus, antibiotic-induced colonization predisposes patients to subsequent endogenous infections with these organisms which, in turn, have been rendered partially or totally resistant to formerly highly active agents. Broad spectrum antimicrobials with a high degree of biliary elimination show a marked impact on the faecal flora. Susceptible enteric bacteria are eliminated within 48 hours and are replaced by enterococci and Candida albicans. Recolonization occurs after discontinuation of therapy by multiresistant organisms like Klebsiella/Enterobacter and Pseudomonas. Oral antibiotics also lead to substantial alterations in the composition and resistance patterns of the faecal flora. In clinical medicine we should be aware of the substantial alterations of the human microflora which may accompany the use of antimicrobial agents.

[Acute tonsillitis: clinical symptoms; bacteriologic culture and rapid test as deciding criteria for the use of antibiotics]. / Akute Tonsillitis: Klinische Symptomatik; bakteriologische Kultur und Schnelltest als Entscheidungskriterien für Antibiotikaeinsatz.

In order to prevent late sequelae from an untreated streptococcal pharyngitis all patients with streptococcal tonsillitis/pharyngitis have to be treated with antibiotics, preferably penicillin. A correct diagnosis by clinical criteria is only achievable in 72% of patients with streptococcal pharyngitis. Additional criteria such as diagnosis by culture are, therefore, mandatory. Time is a major disadvantage of traditional culture methods. Slide agglutination tests show an acceptable sensitivity of 92% and a specificity of 93%. Due to the possibility of false negative test results, with consequent withholding of adequate antimicrobial chemotherapy, these test results should be used only as a valuable guide. Decision to administer an antibiotic should still be based on clinical criteria.

[Correlation of vesico-ureteral reflux and recurrent urinary tract infections with increased bacterial adherence]. / Korrelation von vesikoureteralem Reflux und rezidivierenden Harnwegsinfekten mit erhöhter bakterieller Adhärenz.

Unimpeded urinary flow and voiding of the bladder without residual urine are essential for the prevention of urinary tract infections. Therefore, recurrent urinary tract infections are most commonly found in patients with functional and anatomic disorders of the urinary tract. Children suffering from vesico-ureteral reflux are especially susceptible to recurrent urinary tract infections. The interaction between germ and target cell, i.e. between antigen and receptor, is another important factor in the development of urinary tract infections. This so-called bacterial adherence is variable and depends upon receptor density as well as the affinity of the germ to the receptor. However, our study showed that this bacterial adherence plays a minor role in the development of recurrent urinary tract infections secondary to vesico-ureteral reflux.

[Chemotherapy of severe bacterial infections in pediatrics]. / Chemotherapie schwerer bakterieller Infektionen in der Kinderheilkunde.

Bacterial infections are frequent events in premature and newborn infants. The reason is a defective specific and nonspecific defence of bacterial organisms. Some immunoglobulins like IgM and IgA including secretory IgA are absent. Premature infants also show a decreased level of IgG. Cellular immunity is anatomically intact but functionally defective. A number of complement factors are lacking, the activation of the alternative pathway is impaired. Newborn infants with perinatal problems like asphyxia or difficult delivery, show defects of leucocyte function like decreased deformability, defective chemotaxis and defective killing of ingested bacteria. Certain diseases, like hypoxia and malformations of immature organ functions in this age group (decreased acid production in the stomach), facilitate bacterial colonization of surface epithelia and the invasion of tissues. Consequences of these pathogenetic mechanisms are an unimpaired propagation of bacterial organisms into the blood and meninges without localization of the infecting organisms at the entry site. Bacterial meningitis is not considered a separate disease entity but a complication of bacteremia and sepsis. Clinical symptoms are nonspecific at the onset of the infection. Fever is frequently absent; decreased appetite, vomiting, a bloated abdomen, diarrhea, tachycardia, tachypnea are early signs of a bacterial infection, a grey mottled appearance, cyanosis, jaundice, petechiae, apneic spells, seizure activity and a metabolic acidosis are symptoms of advanced infection. Successful treatment at this stage is often not possible. Every sign of a decreased well being of a newborn of premature infant warrants laboratory and bacteriologic work up for septicemia.(ABSTRACT TRUNCATED AT 250 WORDS)

[Pathogenesis of coli enteritis (author's transl)]. / Zur Pathogenese der Koli-Enteritis.

The pathogenic mechanisms of E. coli in diarrheal diseases were largely obscure up to now. The discovery of an enterotoxin which corresponded with the cholera enterotoxin in its mode of action and is also largely identical with this molecule immunologically provided essentially new aspects of the pathogenic importance of E. coli in diarrheal diseases. The detection of enterotoxin formation depends on the biological test model and presently it is still expensive and unsuitable for routine laboratory use. The serological identification of coli bacteria is meaningless for the detection of enterotoxin formation. Enterotoxic coli are more frequently found (12%) in the large group of hemolytic organisms. In 1978 we isolated enterotoxic coli from the stools of 12 infants under one year old with stubborn diarrhea.

[Bactericidal action of chloramphenicol and synergism with beta-lactam antibiotics]. / Bakterizidie von Chloramphenikol und Synergismus mit beta-Lactam-Antibiotika.

Excellent clinical results were observed with the combination therapy of chloramphenicol with beta-lactam-antibiotics in the treatment of purulent meningitis. This came as a surprise as bacteriostatic antibiotics like chloramphenicol are commonly thought to antagonize the bactericidal action of penicillin or ampicillin. We reevaluated the mode of action of chloramphenicol against the three most common meningeal pathogens after the newborn period. Chloramphenicol was found to be bactericidal against H. influenzae, Streptococcus pneumoniae and Neisseria meningitidis at clinically achievable levels in the CSF. In addition chloramphenicol showed synergistic action with ampicillin against H. influenzae which can possess clinical relevance particularly with the high inoculum of 10(7) organisms/ml which is frequently seen in bacterial meningitis. No synergism was found against Pneumococci and Meningococci but also no antagonism of the lower MIC and MBC values seen with ampicillin and penicillin G. The combination of chloramphenicol with either penicillin or ampicillin constitutes a clinically successful therapeutic regimen which is now also proven by in vitro investigations.