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Background: Selective decontamination of the digestive tract (SDD) is an infection-prevention regimen used in critically ill patients. We assessed the effects of SDD on intensive-care-unit (ICU) and hospital mortality, and on the acquisition of resistant bacteria in adult patients admitted to intensive care., Methods: We did a prospective, controlled, randomised, unblinded clinical trial. 934 patients admitted to a surgical and medical ICU were randomly assigned oral and enteral polymyxin E, tobramycin, and amphotericin B combined with an initial 4-day course of intravenous cefotaxime (SDD group n=466), or standard treatment (controls n=468). Primary endpoints were ICU and hospital mortality and the acquisition of resistant bacteria., Findings: In the SDD group 69 (15%) patients died in the ICU compared with 107 (23%) in the control group (p=0.002). Hospital mortality was lower in the SDD groups than in the control group (113 [24%] vs 146 [31%], p=0.02). During their stay in intensive care, colonisation with gram-negative bacteria resistant to ceftazidime, ciprofloxacin, imipenem, polymyxin E, or tobramycin occurred in 61 (16%) of 378 SDD patients and in 104 (26%) of 395 patients in the control group (p=0.001). Colonisation with vancomycin-resistant enterococcus occurred in five (1%) SDD patients and in four (1%) controls (p=1.0). No patient in either group was colonised with meticillin-resistant Staphylococcus aureus., Interpretation: In a setting with low prevalence of vancomycin-resistant enterococcus and meticillin-resistant S aureus, SDD can decrease ICU and hospital mortality and colonisation with resistant gram-negative aerobic bacteria.

In The Netherlands, national guidelines for the treatment of adult patients with bacterial meningitis were introduced in October 1997. In 1998 we began a prospective, nationwide study to evaluate the compliance with these consensus-based guidelines. In addition, we evaluated whether the recommended initial treatment provides adequate microbiological coverage. From October 1998 to January 2000, 365 adults with bacterial meningitis were identified using information from The Netherlands Reference Laboratory for Bacterial Meningitis; 263 patients were classified into four categories depending on patient's age and underlying health status. In the first category, patients 16-60 years without risk factors, Neisseria meningitidis was the most common pathogen (53%); 62 of 127 patients (49%) received treatment in compliance with the guidelines. In the second and third categories, patients >60 years without risk factors and those with risk factors independently of age, Streptococcus pneumoniae caused 61% and 58% of cases, respectively. Compliance in these categories was about 17%. Overall, 33% of patients received treatment in compliance with the guidelines. The microbiological coverage of patients treated in compliance and not in compliance with the guidelines was 98% and 93%, respectively. In conclusion, 1 year after national consensus-based guidelines for the initial treatment of adult patient with bacterial meningitis were introduced in The Netherlands, only one-third of Dutch physicians were adhering to the guidelines. The microbiological coverage for the patients who were treated in compliance with the guidelines was almost complete (98%).

Of 96 Helicobacter pylori isolates from patients in Shanghai and Guangzhou, China, 5 had the A2143G 23S rRNA mutation as determined by primer-mismatch PCR and were resistant to clarithromycin by the E-test. The remaining isolates were primer-mismatch PCR negative and susceptible to clarithromycin. The conclusion is that the prevalence of clarithromycin-resistant H. pylori isolates among these Chinese patients is 5%.

Of the Helicobacter pylori populations from 976 patients, six contained clarithromycin-resistant as well as -susceptible colonies. In each heterogeneous H. pylori population, resistant H. pylori colonies harbored identical 23S ribosomal DNA (rDNA) mutations associated with clarithromycin resistance, while the susceptible H. pylori colonies all had wild-type 23S rDNA. The resistant and susceptible colonies of each of the heterogeneous H. pylori populations had identical randomly amplified polymorphic DNA-PCR genotypes. In conclusion, evaluation of antimicrobial susceptibility can be misinterpreted if only a single colony from the primary H. pylori population is used to test for clarithromycin susceptibility.

As resistance increases against fungal antibiotics, antimicrobial peptides are receiving attention as possible replacements. The dermal glands of frogs secrete, among other things, antimicrobial peptides. As part of the innate immune system, stressors may affect the production of antimicrobial peptides by dermal glands. The dermal secretions of some salamanders have been examined for their toxic secretions, but little attention has been given to salamander antimicrobial peptides. This study examines the skin from the tail region for the production of antimicrobial peptides in the terrestrial salamander, Plethodon cinereus. Fractions of tail extracts were isolated using cation-exchange chromatography and reverse-phase HPLC. An HPLC fraction eluting at 15.75 min (HPLC run: 30 min, 30-80% acetonitrile/water gradient, Aquapore RP-300 C18 column) showed activity against Staphylococcus aureus but not against Escherichia coli. The antibacterial activity gradually increased over a 4-hr incubation time up to about 85% inhibition of bacterial growth. Lysis of guinea pig red blood cells also increased gradually over a 1-hr time period. J. Exp. Zool. 287:340-345, 2000., (Copyright 2000 Wiley-Liss, Inc.)

Antibacterial proteins are components of the innate immune system found in many organisms and produced by a variety of cell types. Human blood platelets contain a number of antibacterial proteins in their alpha-granules that are released upon thrombin activation. The present study was designed to purify these proteins obtained from human platelets and to characterize them chemically and biologically. Two antibacterial proteins were purified from platelet granules in a two-step protocol using cation exchange chromatography and continuous acid urea polyacrylamide gel electrophoresis and were designated thrombocidin (TC)-1 and TC-2. Characterization of these proteins using mass spectrometry and N-terminal sequencing revealed that TC-1 and TC-2 are variants of the CXC chemokines neutrophil-activating peptide-2 and connective tissue-activating peptide-III, respectively. TC-1 and TC-2 differ from these chemokines by a C-terminal truncation of 2 amino acids. Both TCs, but not neutrophil-activating peptide-2 and connective tissue-activating peptide-III, were bactericidal for Bacillus subtilis, Escherichia coli, Staphylococcus aureus, and Lactococcus lactis and fungicidal for Cryptococcus neoformans. Killing of B. subtilis by either TC appeared to be very rapid. Because TCs were unable to dissipate the membrane potential of L. lactis, the mechanism of TC-mediated killing most probably does not involve pore formation.

If shunts, inserted for the relief of hydrocephalus, are pretreated with antimicrobials, the incidence of shunt-associated infections (SAI) may be reduced. The duration of the antibacterial activity of shunts, made from conventional silicon elastomer (SE) or from SE grafted with the hydrogel polyvinylpyrrolidone (SEpvp), which had been soaked in various antibiotics, was assessed in vitro. For any antibiotic or combination, using an arbitrary breakpoint (aBP), SEpvp remained antibacterially active for longer periods than SE. Bacterial adherence to either shunt was prevented during the period of antibacterial activity. Thus, the aBP is a good indicator of the capacity of antimicrobial-treated shunts to prevent bacterial colonization in vitro. Hydrogel-grafting of shunts may be useful in preventing SAI.

There has been growing interest in recent years in early switch therapy: antibiotics are administered intravenously during the early phase of the infection, and then continued orally. A large number of recent prospective and randomized studies justify the application of an early switch. There is consensus in the literature about the circumstances in which an early switch is justified: (a) the patient must show clinical improvement; (b) the oral therapy should result in sufficiently high levels at the infection site; (c) the patient must be capable of taking oral medication, there must be no signs of malabsorption and interactions with food or with other drugs should be taken into account; (d) if these rules are observed, switch to oral therapy as a rule is justified after 2 to 3 days' intravenous administration. An early switch is more comfortable to the patient, eases the load on the nursing staff and considerably reduces expenses.

Nonencapsulated Haemophilus influenzae frequently persists in the lungs of chronic obstructive pulmonary disease (COPD) and cystic fibrosis (CF) patients for prolonged periods of time. The bacteria are not eradicated by antibiotic treatment of the patients or by specific antibodies that are found in the sputum and sera of these patients. We investigated whether H. influenzae, when localized in lung epithelial cell layers, is shielded from antibiotics and from antibody-mediated bactericidal activity of specific antibodies. An in vitro model system consisting of lung epithelial NCI-H292 cells on permeable supports was developed to allow long term association of H. influenzae with the cells. Microscopic examination showed increasing numbers of H. influenzae bacteria between the epithelial cells up to 24 h of incubation. Coinciding with the microscopic observations the maximum number of cell-associated bacteria surviving gentamicin treatment of the cell layers was obtained after 24 h of incubation. All H. influenzae strains, and one Haemophilus parainfluenzae strain tested penetrated into the cell layer as determined by gentamicin killing. Cell-associated bacteria were shielded from the bactericidal activity of several antibiotics and from antibody-mediated bactericidal activity. After prolonged incubation in the cell system in the presence of a specific bactericidal antibody against major outer membrane protein (MOMP) P2, antigenic variation occurred due to a point mutation in the MOMP P2 gene, similar to point mutations observed in vivo. We conclude that penetration of H. influenzae between lung epithelial cells results in shielding the bacteria from killing by antibody dependent defense mechanisms and by antibiotics. Therefore, penetration of H. influenzae between epithelial cells may contribute to the persistence of this microorganism in COPD and CF patients., (Copyright 1999 Academic Press.)

In recent years 'switch therapy' has been advocated: short intravenous antibiotic therapy, for 2-3 days, followed by oral treatment for the remainder of the course. Little is known about the number of patients that could benefit from early switch therapy and the consequences of introducing this strategy in everyday practice. We prospectively registered all antibiotic courses on wards for Internal Medicine, Surgery, and Pulmonology during a 2 month period, before (n = 362, inventorial phase) and after (n = 281, implementation phase) the introduction of guidelines for switching therapy. Approximately 40% of all patients who started on iv antibiotics were candidates for an early iv-oral switch. During the inventorial phase, 54% (52/97) of eligible patients were switched to oral treatment, after a median of 6 days (range 2-28 days). After implementation of the guidelines, this percentage rose to 83% (66/80) (difference 29%, 95% CI 16-42%; P < 0.001). Therapy was also switched earlier, after a median of 4 days (range 2 to 16 days). In the 6 weeks after completion of the oral course, recurrence of infections, or readmissions due to reinfections did not occur. Compared with the inventorial phase, 43% of iv administrations could be avoided, that is >6000 per year. This means a potential annual reduction of dfl.60,000 (c. US$30,000) of administration costs. The potential savings in purchase costs of the antibiotics were dfl.54,000 (US$27,000) annually. In conclusion, a substantial number of patients starting on iv antibiotics were candidates for an early iv-oral switch. The guidelines were well accepted by the physicians and substantial savings in costs and nursing time were achieved.

Prosthetic valve endocarditis is an infrequent, but serious complication of cardiac valve replacement. The infection is caused by the adherence of bacteria to the prosthetic valve or to tissue at the site of implantation. Recently it was shown that antibacterial peptides from blood platelets are involved in clearance and killing of bacteria adhering to vegetations induced in a model for prosthetic valve endocarditis using rabbits. The application of these antibacterial proteins in a release system, incorporated in the Dacron sewing ring of the prosthetic heart valve would diminish the incidence of endocarditis. In this study a release system for small cationic proteins based on cross-linked gelatin was developed and characterised. Furthermore, the system was evaluated with respect to the uptake and in vitro release of lysozyme, a small cationic protein that was chosen as a model protein for small cationic antibacterial proteins. Variation of gelatin type (A and B), and cross-link density resulted in differences in swelling, thermal behaviour, and number of charged groups. Lysozyme uptake was proportional to swelling, but was governed by the number of anionic groups. The latter was also observed for the release profiles: when the amount of free carboxylic acids is higher (gelatin B compared to gelatin A), the lysozyme release lasts for a longer time period. The release into solidified agarose medium, as a model for heart muscle tissue, was measured. After 50 h, 40-100% of the lysozyme was released, which is in accordance with the aimed release period of 24-48 h. The adsorption experiments in vitro suggest an influence of the electrostatic interactions between lysozyme and gelatin. This hypothesis was validated with a mathematical model which takes both diffusion and adsorption interactions into account.

We analyzed the antimicrobial susceptibilities of Haemophilus influenzae isolates from 157 sputum specimens prospectively collected from 39 cystic fibrosis (CF) patients during a 2-year study. These isolates were characterized by random amplified polymorphic DNA analysis and major outer membrane protein (MOMP) analysis to identify H. influenzae strains and MOMP variants and to assess their persistence in the respiratory tract. Among the 247 H. influenzae isolates, 16 (6.5%) produced beta-lactamase. The 231 beta-lactamase-negative isolates represented 85 H. influenzae strains, 61 MOMP variants derived from 27 of these strains, and 85 persistent isolates identical to strains or MOMP variants. All beta-lactamase-negative isolates were tested for susceptibility to ampicillin, amoxicillin-clavulanic acid, cefuroxime, cefotaxime, cefaclor, imipenem, tetracycline, and trimethoprim-sulfamethoxazole by disk diffusion testing. Eleven (13%) H. influenzae strains, 18 (30%) MOMP variants, and 30 (35%) persistent isolates were resistant to one or more of the antibiotics tested. Antimicrobial susceptibility was decreased among MOMP variants and persistent isolates compared to nonpersistent H. influenzae strains, and changes in susceptibility occurred irrespective of MOMP variation. We conclude that the decreased antimicrobial susceptibility of H. influenzae during persistence contributes to the poor eradication of H. influenzae from the respiratory tracts of CF patients.

Bacterial resistance against antibiotic treatment is becoming an increasing problem in medicine. Therefore methods to destroy microorganisms by other means are being investigated, one of which is photodynamic therapy (PDT). It has already been shown that a variety of Gram-positive and Gram-negative bacteria can be killed in vitro by PDT using exogenous sensitizers. An alternative method of photosensitizing cells is to stimulate the production of endogenous sensitizers. The purpose of this study was to investigate the bactericidal efficacy of PDT for Haemophilus parainfluenzae with endogenously produced porphyrins, synthesized in the presence of delta-aminolaevulinic acid (delta-ALA). H. parainfluenzae incubated with increasing amounts of delta-ALA showed decreased survival after illumination with 630 nm light. No photodynamic effect on the bacterial viability was found when H. parainfluenzae was grown without added delta-ALA. H. influenzae, grown in the presence of delta-ALA, but not capable of synthesizing porphyrins from delta-ALA, was not affected by PDT. Of the range of incident wavelengths, 617 nm appeared to be the most efficient in killing the bacteria. Spectrophotometry of the bacterial porphyrins demonstrated that the maximum fluorescence occurred at approximately 617 nm, with a much lower peak around 680 nm. We conclude that a substantial killing of H. parainfluenzae by PDT in vitro after endogenous sensitization with delta-ALA can be achieved.

Endotoxin is liberated following antibiotic killing of Gram-negative rods, and antibiotics may differ in this respect. Although the amount of filterable endotoxin has also been reported to increase following antibiotic killing of meningococci, it is unknown how this influences the host response. We investigated the influence of three antibiotics on levels of free endotoxin in culture medium and cytokine production in whole blood ex vivo during killing of four strains of meningococci. Bacterial killing was significantly more efficient with penicillin or ceftriaxone than with chloramphenicol, and free endotoxin levels were lower after exposure to antibiotics as compared with no treatment (ANOVA, P < 0.001). Endotoxin levels were lowest after exposure to chloramphenicol. In three of the four strains exposure to antibiotics resulted in considerably lower cytokine levels (ANOVA, P < 0.001), and TNF-alpha levels were significantly lower after exposure to penicillin or ceftriaxone than after chloramphenicol treatment. Only in the strain that induced the lowest levels of TNF-alpha were cytokine levels comparable for untreated and treated samples. We conclude that fear of excessive endotoxin release or cytokine production caused by effective antibiotics is not justified in the treatment of meningococcal infections.

The increasing antimicrobial resistance among pathogens frequently isolated from patients with bacterial meningitis formed the rationale to perform a surveillance study to determine the prevalence of resistance in The Netherlands. Haemophilus influenzae strains (n = 316) isolated from cerebrospinal fluid (CSF), 1125 meningococcal strains isolated from blood or CSF and 398 pneumococcal strains isolated from CSF in 1993 and 1994 were tested by the Etest for susceptibility to commonly prescribed antibiotics for the treatment of community-acquired meningitis. In H. influenzae strains ampicillin-resistance occurred in 7.0%, resistance to chloramphenicol in 2.2%, and resistance to both antibiotics in 0.9%. The prevalence of intermediate penicillin-resistance in meningococci was 3.3%. Resistance to rifampicin was rarely found (0.1%). Intermediate penicillin-resistance in pneumococci was found in only 0.5% of isolates. All 1839 isolates were susceptible to ceftriaxone. Based on these results, we conclude that empirical therapy of childhood community-acquired bacterial meningitis with amoxycillin and chloramphenicol is no longer justified in children who have not been vaccinated against H. influenzae type b. In vaccinated or older children and adults, amoxycillin is a rational choice for empirical treatment of meningitis. The prophylactic use of rifampicin in contacts of patients with meningococcal disease is still applicable.

Cholangitis is usually the consequence of a combination of factors: impairment of the flow of bile and bacterial colonization of the biliary tract. Although reestablishing biliary drainage is the mainstay of treatment, antibiotics play an important role in the management of cholangitis. In this review, the use of antibiotics for treatment, prophylaxis, and maintenance therapy is discussed. Antibiotics for the treatment of acute cholangitis should be given for 7-10 days in therapeutic dosages and may allow a more selective timing of further interventions. Antibiotic prophylaxis for cholangitis ought to be given as a single (high) dose shortly before surgical or nonsurgical manipulations of the biliary system. Patients with a compromised biliary system (e.g., on account of an endoprosthesis in situ or hepaticojejunostomy) who are prone to develop recurrent bouts of cholangitis may benefit from antibiotic maintenance therapy, given daily in lower-than-therapeutic dosages.

The effect of two prophylactic antibiotic regimens during cardiopulmonary bypass (CPB) was investigated in dogs. Airborne contamination was determined by spraying two different bacterial strains (Staphylococcus aureus and Serratia marcescens) into the air of the operating room. Dogs were operated on and underwent CPB with a bubble oxygenator. Pericardial suction, either conventional (blood-air) or selective (only blood), was used. Particularly in the first situation, an impaired humoral host defense is induced. In dogs given the regimen consisting of penicillin G (benzylpenicillin), gentamicin sulfate, and flucloxacillin, the number of contaminated sites for both bacteria was reduced (p less than .01) compared with those given cefuroxime. The effectiveness of the combined antibiotic regimen could be ascribed to increased serum bactericidal activity and polymorphonuclear leukocyte (PMN) killing capacity. Cefuroxime enhanced the PMN respiratory burst. As a result, two weeks postoperatively the rate of infection was small in both groups. We conclude that prior to CPB, antibiotics should be administered prophylactically to overcome a period of impaired humoral host defense during CPB.