Prevention and treatment of health care-acquired infections

Health care-acquired infections present a tremendous challenge to the care of hospitalized patients. Unfortunately, the risk of acquiring a health care-associated infection (HAI) is rising. The vast majority of HAI are of four types: urinary tract infections, surgical site infections, bloodstream infections, and pneumonia. This chapter aims to provide current data and strategies relating to the prevention of HAIs among hospitalized patients.     

Frakturen der distalen Mittelhandknochen

Distal metacarpal fractures are often displaced and accompanied by rotational malposition of the finger in question. Closed reduction and plaster immobilization usually requires extended periods of time for the fracture to heal and does not always result in optimal fracture positions. Through December 2007, 168 patients with fractures in the distal portion of metacarpal bones underwent operation. They were treated by proximally inserted intramedullary Kirschner (K) wires. At defined time points, all patients were examined to determine range of movement of the finger joints and the strength of the hands. Clinical and radiological controls were performed, comparing both hands. The results were also assessed after healing using the Disability of Arm, Shoulder and Hand (DASH) score. In most distal metacarpal fractures, good or very good results can be achieved using intramedullary osteosynthesis with modeled K-wires.     

Coadministration of oral levofloxacin with agents that impair its absorption: potential impact on emergence of resistance

Coadministration of fluoroquinolones (FQs) with divalent or trivalent cation-containing compounds (DTCCs) inhibits FQ absorption. In a case-control study of 46 inpatients receiving oral levofloxacin and DTCCs, patients with a levofloxacin-resistant isolate had been previously exposed to nearly twice as many days of levofloxacin/DTCC coadministration (P = 0.04). There remained a borderline significant independent association between the number of days of coadministration and levofloxacin-resistant culture [adjusted odds ratio (95% confidence interval) = 1.26 (0.98, 1.63); P = 0.07], even after controlling for the length of the levofloxacin course and the duration of hospitalisation prior to initiation of levofloxacin. Efforts should be directed at modifying hospital policies for dosing of levofloxacin and DTCCs to prevent coadministration.     

Emergence of resistance to chloramphenicol among vancomycin-resistant enterococcal (VRE) bloodstream isolates

Therapeutic options for vancomycin-resistant enterococcal (VRE) bloodstream infections are extremely limited. Chloramphenicol is effective when VRE isolates are susceptible to this agent. However, longitudinal trends in chloramphenicol-resistant VRE (CR-VRE) are unknown. The possible association between CR-VRE and antibiotic use has not been studied. We analyzed the antimicrobial susceptibility profiles of all VRE blood isolates from 1991-2000 at our institution. We performed a correlational study to examine the relationship between annual hospital-wide use of specific antibiotics and antibiotic classes and CR-VRE prevalence. During the 10-year study period, the prevalence of CR-VRE increased from 0 to 11% ( P< 0.001, trend). CR-VRE prevalence was correlated only with chloramphenicol use (P=0.05 ) and quinolone use (P= 0.01 ). If these trends continue, dependence on newer, more expensive agents will increase. The correlation between both chloramphenicol use and quinolone use and the prevalence of CR-VRE suggests that efforts to preserve the utility of chloramphenicol in VRE infections may depend on optimizing the use of these agents.     

Longitudinal trends in antimicrobial susceptibilities across long-term-care facilities: emergence of fluoroquinolone resistance.

BACKGROUND: Antibiotic resistance in the longterm-care facility (LTCF) setting is of increasing concern due to both the increased morbidity and mortality related to infections in this debilitated population and the potential for transfer of resistant organisms to other healthcare settings. Longitudinal trends in antibiotic resistance in LTCFs have not been well described. DESIGN: Correlational longitudinal survey study. SETTING: Four LTCFs in Pennsylvania. SUBJECTS: All clinical cultures of residents of the participating LTCFs (700 total beds) from 1998 through 2003. We assessed the annual prevalence of resistance to various antimicrobials of interest for the following organisms: Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Pseudomonas aeruginosa, Staphylococcus aureus, and enterococcus species. RESULTS: A total of 4,954 clinical isolates were obtained during the study. A high prevalence of antimicrobial resistance was noted for many organism-drug combinations. This was especially true for fluoroquinolone susceptibility among the Enterobacteriaceae (susceptibility range, 51.3% to 92.2%). In addition, the prevalence of resistance to various agents differed significantly across study sites. Finally, significant increasing trends in resistance were noted over time and were most pronounced for fluoroquinolone susceptibility among the Enterobacteriaceae. CONCLUSIONS: The prevalence of antimicrobial resistance has increased significantly in LTCFs, although trends have varied substantially across different institutions. These trends have been particularly pronounced for fluoroquinolone resistance among the Enterobacteriaceae. These findings demonstrate that antimicrobial resistance is widespread and increasing in LTCFs, highlighting the need for future studies to more clearly elucidate the risk factors for, and potential interventions against, emerging resistance in these settings.     

Limiting the emergence of extended-spectrum Beta-lactamase-producing enterobacteriaceae: influence of patient population characteristics on the response to antimicrobial formulary interventions.

BACKGROUND: Effective methods to control the emergence of extended-spectrum beta -lactamase-producing Escherichia coli and Klebsiella species (ESBL-EK) remain unclear. Variations in the patient populations at different hospitals may influence the effect of antimicrobial formulary interventions. METHODS: To examine variations across hospitals in the response to antimicrobial interventions (ie, restriction of ceftazidime and ceftriaxone) designed to curb the spread of ESBL-EK, we conducted a 5-year quasi-experimental study. This study was conducted at 2 hospitals within the same health system: Hospital A is a 625-bed academic medical center, and Hospital B is a 344-bed urban community hospital. All adult patients with a healthcare-acquired clinical culture of ESBL-EK from July 1, 1997 through December 31, 2002 were included. RESULTS: After the interventions, the use of ceftriaxone decreased by 86% at Hospital A and by 95% at Hospital B, whereas the use of ceftazidime decreased by 95% at Hospital A and by 97% at Hospital B. The prevalence of ESBL-EK at Hospital A decreased by 45% (P < .001), compared with a 22% decrease at Hospital B (P = .36). The following variables were significantly more common among ESBL-EK-infected patients at Hospital B: residence in a long-term care facility (adjusted odds ratio, 3.77 [95% confidence interval, 1.70-8.37]), advanced age (adjusted odds ratio, 1.04 [95% confidence interval, 1.01-1.06]), and presence of a decubitus ulcer (adjusted odds ratio, 4.13 [95% confidence interval, 1.97-8.65]). CONCLUSIONS: The effect of antimicrobial formulary interventions intended to curb emergence of ESBL-EK may differ substantially across institutions, perhaps as a result of differences in patient populations. Variability in the epidemiological profiles of ESBL-EK isolates at different hospitals must be considered when designing interventions to respond to these pathogens.     

Resorcinarenes with 2-benzimidazolone bridges: self-aggregation, self-assembled dimeric capsules, and guest encapsulation

The synthesis and spectroscopic characterization of self-assembled dimeric resorcinarenes 1a-d containing four 2-benzimidazolone (cyclic urea) bridges are reported. The nanometer-size capsules are held together by a cyclic array of complementary hydrogen bonds. Unlike the related imide-bridged resorcinarenes reported by Rebek and coworkers [Heinz, T., Rudkevich, D. M. & Rebek, J., Jr. (1998) Nature (London) 394, 764-766], these strongly bound dimers aggregate in chloroform solutions yielding different self-organized structures, depending on the nature and length of the four carbon chains attached at the bottom of each resorcinarene platform, as revealed by transmission electron microscopy. Thus, phenethyl groups (dimer 1c x 1c) produce long fibers, probably arising from tail to tail contacts and subsequent threading of the resulting linear self-assembled polymers, whereas long alkyl chains (dimers 1a x 1a and 1b x 1b) induce formation of large reverse vesicles of 0.8-2.2 microm diameter through side to side extensive stacking. Presumably, the rigidity of the dimer precludes folding of the aggregate into smaller vesicles. On the contrary, dimer 1d. 1d, containing four nine-carbon chains and a cis-double bond, does not substantially aggregate and gives rise to reasonably resolved (1)H NMR spectra. The compound was shown to be dimeric either by matrix-assisted laser desorption ionization-time-of-flight and vapor pressure osmometry. Encapsulation studies were followed by NMR. Propionic or pivalic acid was included in the capsules, probably as head to head hydrogen-bonded dimers in mesitylene-d(12), a solvent too big to be a guest by its own. Longer dimeric carboxylic acids or larger substrates, like 2-adamantyl azide or cyclohexylcarbodiimide, do not encapsulate, but mixtures of a long and a short carboxylic acid (i.e., propionic-adamantyl or propionic-cyclohexyl) yield pairwise complexes.     

Additive effects of dipyridamole and Trolox in protecting human red cells during photodynamic treatment

BACKGROUND AND OBJECTIVES: Photodynamic treatment (PDT) of red blood cell (RBC) suspensions has been reported to result in virus inactivation, but also in deterioration of cell quality. Recently, we have demonstrated the potential usefulness of the reactive oxygen species scavenger dipyridamole in selectively protecting RBCs against the harmful side-effects of PDT. Unfortunately, dipyridamole-conferred protection against long-term photohaemolysis was incomplete. In the present study, dipyridamole was applied in combination with Trolox (a hydrophilic vitamin E analogue) in order to augment RBC protection. MATERIALS AND METHODS: Leucodepleted RBC suspensions (30% haematocrit) were treated with 1,9-dimethylmethylene blue (DMMB) and red light, and the effect of inclusion of dipyridamole and Trolox was assessed on potassium leakage as well as on short-term and long-term photohaemolysis. Possible interference of the scavenger cocktail with virus inactivation was examined using extracellular pseudorabies virus (PRV). RESULTS: Treatment of RBC with DMMB and red light resulted in enhanced potassium leakage and both short- and long-term haemolysis. Dipyridamole and Trolox showed additive protective effects against induction of potassium leakage and photohaemolysis, suggesting different protection mechanisms for the two scavengers. Combined inclusion of dipyridamole and Trolox did not interfere with efficacy of PRV inactivation. CONCLUSIONS: Combined inclusion of dipyridamole and Trolox results in substantially improved selectivity of photodynamic treatment of RBC suspensions.     

Die Anwendung von Prostaglandin E1 bei mikrovaskulären Rekonstruktionen der oberen Extremität nach Akuttraumen

The operative treatment of hand and upper extremity trauma with injury of main vessels becomes a daily standard work in trauma and microsurgical replantation centers. The techniques of vessel and soft tissue reconstruction are well known. The outcome of the replantation depends on various factors. Main influences are the intraoperative status of the vessel wall and the unobstructed flow in the vessel after the operation. Another factor for successful replantation is the homeostasis of the patient. It can be influenced by many drugs which are applied according to a replantation schema. Aim of this therapy is the correction of the rheologic properties of a patient. In a patient group of 25 treated with Prostaglandin E1 (Prostavasin) we observed better wound healing with a 80% rate of successful replantation and microvascular vessel reconstruction.     

Gains in life expectancy after elimination of major causes of death: revised estimates taking into account the effect of competing causes

BACKGROUND: It is generally acknowledged that conventional estimates of the potential number of life years to be gained by elimination of causes of death are too generous. This is because these estimates fail to take into account the fact that those who are saved from the cause are likely to have one or more other conditions ("competing" causes of death), which may increase their risks of dying. It is unknown to what extent this introduces bias in comparisons of life years to be gained between underlying causes of death. The purpose of the study was to assess this bias. DATA AND METHODS: A sample of 5975 death certificates from the Netherlands, 1990, was coded for the presence of diseases that, according to a set of explicit rules, could be regarded as potential causes of death "competing" with the underlying cause. Logistic regression analysis was used to quantify age and sex adjusted differences between four main underlying causes of death (neoplasms, cardiovascular diseases, respiratory diseases, all other diseases) in prevalence of the six most frequent competing causes of death (neoplasms, ischaemic heart disease, cerebrovascular disease, other cardiovascular diseases, chronic obstructive lung disease, all other diseases). These prevalence differences were then used to revise conventional calculations of gains in life expectancy, by taking them to indicate differences in risk of dying from these competing causes after the underlying cause has been eliminated. RESULTS: The prevalence of competing causes of death is relatively low among persons dying from neoplasms as the underlying cause, about average among persons dying from cardiovascular diseases, and relatively high among persons dying from respiratory diseases. Taking this into account results in substantial decreases of potential life years to be gained by elimination of cardiovascular diseases and respiratory diseases, relative to the number of years to be gained by elimination of neoplasms. Specifically, while according to the conventional calculations the gain in life expectancy by elimination of cardiovascular diseases exceeds that for neoplasms by more than one year, in the revised calculations the number of life years to be gained is approximately equal. CONCLUSIONS: Despite its limitations, mainly relating to reliance on death certificate data, this study suggests that conventional estimates of differences between underlying causes of death in life years to be gained by elimination are seriously biased by ignoring the effects of competing causes. Specifically, the relative impacts of eliminating cardiovascular diseases and respiratory diseases, as compared with eliminating neoplasms, seem to be overestimated. The implications are discussed.