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Category: Clinical Microbiology
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Indwelling prosthetic devices such as catheters, heart valves, vascular bypass grafts, ocular lenses, artificial joints, and central nervous shunts have become a common and indispensable part of medical care. The development and implantation of prosthetic aids and materials are likely not only to continue but also to increase in the near future. Associated with these prosthetic materials is an increased risk of infection after implantation.
Completely revised and rewritten, the third edition of this best-selling volume reviews the available information about these infections. This new volume covers the physical factors responsible for bacterial adherence; the molecular and genetic basis of adherence of staphylococci; new clinical problems; novel therapeutic or preventive approaches, such as treatment of ambulatory-care prosthetic material-associated osteomyelitis; identification and therapy of infected dental implants; and prevention and treatment of catheter-related infections.
Infections Associated with Indwelling Medical Devices offers an exhaustive and comprehensive treatment of the complex problems related to medical-device infections and will be a valuable reference for clinicians and researchers.
Hardcover, 436 pages, illustrations, index.
A major argument in favor of local defects in the host defense against staphylococcal foreign-body infections was obtained by studies performed with experimentally infected animals. Effective protection from foreign-body infection was indeed obtained by injection of fresh neutrophils into tissue cages. In vitro studies aiming to describe mechanisms of bacterial attachment relevant to the colonization of indwelling devices are frequently performed in the absence of any hostrelevant factors. A section of this chapter emphasizes the critical role of host proteins, whether surface-bound or in the fluid phase, in modulating staphylococcal attachment to artificial implants. More recent studies using specific adhesin-defective mutants of Staphylococcus aureus confirmed the role of fibronectin in promoting bacterial attachment to subcutaneously implanted coverslips. The high susceptibility of patients with indwelling devices to microbial infections results from important defects in the cytokine and phagocytic-bactericidal responses. Experimental models have documented these defects in the vicinity of subcutaneously implanted tissue cages locally challenged with S. aureus or S. epidermidis. Such implanted tissue cages or coverslips were found to be progressively colonized by host-derived humoral and cellular elements. A number of approaches may be considered for reducing host susceptibility to foreign-body infections. An improved understanding of molecular and physiological mechanisms of phenotypic antibiotic tolerance of implant-associated organisms might bring new clues to more effective treatment strategies.
This chapter focuses on the fibronectin-binding proteins (FnBPs) and fibrinogen-binding proteins (clumping factors, Clf) of Staphylococcus aureus. The role of the proteins in promoting bacterial adherence to immobilized ligand has been defined using site-specific adhesin-defective mutants that are compared with the parental strains in in vitro and in vivo models of foreign-body infection. The fnbA and fnbB genes of the laboratory strain 8325-4 have been inactivated by allelic replacement. This fnbAfhbB double mutant and the mutant carrying a multicopy plasmid that causes overexpression of FnBPA have allowed the role of FnBPs in promoting bacterial interactions with fibronectin to be defined. The fnbAfnbB mutant of strain 8325-4 was also defective in adherence to coverslips removed from subcutaneous chambers implanted in guinea pigs. The growth conditions used to prepare the bacterial cells for the adherence and virulence experiments would have prevented expression of the second clumping factor ClfB. The ClfA- mutant was defective in adherence to immobilized fibrinogen, while the complemented mutant adhered as well as the wild-type. The increasing incidence of multiple-antibiotic-resistant strains causing nosocomial infections has increased the urgency for alternative approaches to prevention and therapy. The problem is compounded by the recent emergence of methicillin-resistant S. aureus (MRSA) with intermediate sensitivity to vancomycin. In conclusion, there are several experimental vaccines that provide clear protection against S. aureus infections in animals. The challenge is to determine if any of these will protect human patients against nosocomial disease and, in particular, biomaterial-related infection.
A variant subpopulation of Staphylococcus aureus has been characterized that is defective in electron transport. These organisms grow slowly and are typical of the small-colony variants (SCVs), which were found to be defective in respiratory activity. Recent work has shown that most of the clinical isolates have inactive electron transport because of biosynthetic defects in the pathways leading to the synthesis of electron transport chain components. The changes in membrane potential and ATP also suggest that electron transport is decreased in both SCVs and adherent bacteria. SCVs from a variety of genera and species have most frequently been isolated from patients and animals treated with antibiotics, especially aminoglycosides, but also sulfonamides and β-lactam antibiotics. The host environment may favor the selection of staphylococcal SVCs. The basis for the persistent and antibiotic resistant infections may be related to the ability of S. aureus SCVs to reside within cultured cells. Pigment formation and aminoglycoside transport require ATP and an intact electron transport system. The yellow carotenoid pigments that give S. aureus SCV colonies their characteristic color require ATP for their biosynthesis. Menadione and hemin are the two most frequent substances that reverse the S. aureus SCV phenotype. In addition, thiamine is a co-factor used in menadione biosynthesis and CO2 may be involved in the synthesis of the porphyrin ring found in hemin.
In 1981, intravenous catheters infected with staphylococci by perfusion were investigated by scanning electron microscopy (SEM) to demonstrate the mode of adhesion. Bacterial cells, primarily those of staphylococci, followed by Acinetobacter calcoaceticus and Pseudomonas aeruginosa, were shown to be attached to the inner surface of the catheter. The thickest bacterial layers were found in catheters infected by coagulase-negative staphylococci (CoNS). Right heart flow-directed catheters removed from 18 critically ill patients after an average of 2.6 days after insertion were covered by a bacterial biofilm. In a neonatal intensive care unit, CoNS caused the majority of the nosocomial bacteremias. A study of arterial and central venous catheters removed from patients after 1 to 14 days revealed an extensive biofilm on all 42 arterial and 26 central venous catheters. By using special biofilm culture recovery methods, it was shown that 81% of the catheters were colonized by bacteria growing in slime-enclosed biofilms. It was speculated that the colonization represents a nidus for infection and bacteremia in these patients. Staphylococci also produced biofilm on polyvinyl chloride (PVC) endotracheal tubes used in neonates. Adherence of staphylococci to various intravascular catheter materials was investigated; these materials were composed of silicone elastomer, thermoplastic polyurethane, and polyurethane coated with Hydromer, a coating that absorbs water and provides a hydrophilic sheath around the catheter. Production of slime is necessary for Staphylococcus epidermidis colonization and is also observed with many other pathogens, including S. aureus.
For more than a decade, various aspects of medical device and biomaterial infections have been studied in an effort to develop a fundamental and applied basis for infection-resistant biomaterials. This chapter presents an approach and perspectives on factors favoring biomaterial colonization and infection. Infection is a potentially serious complication with implants and devices and a major impediment to the long-term clinical success of devices like vascular grafts, artificial heart valves, and ventricular assist devices. The microorganisms most frequently identified on infected polymer implants either are present in the host flora or are nosocomial in origin, most notably the coagulasenegative staphylococci, particularly Staphylococcus epidermidis. The virulence of the commensal S. epidermidis is a result of the foreign-body implant, which acts to inhibit the normal host defense. Focal thrombosis is a common finding with cardiovascular devices such as prosthetic heart valves, vascular grafts, arteriovenous fistulas, and artificial hearts. Catastrophic failure with significant morbidity and possibly death may occur when infectious foci initiate thrombosis with subsequent septic embolization. Adhesion of bacteria to an implant surface through specific and nonspecific mechanisms is a critical initial step in the development of biomaterial-centered infection. The adhesion of S. epidermidis directly on biomaterials appears to be governed by nonspecific interactions. The GRGDS pentapeptide sequence was selected as the inhibitor, since it binds to several platelet integrin receptors, including GPIIb/IIIa. The complement system and phagocytic leukocytes, which are the primary defense mechanisms against infection, are obvious targets for the down regulation of host defenses by the biomaterial.
The pathogenesis of vascular catheter infections has recently been extensively reviewed. This chapter summarizes existing understandings and presents details of new work published on vascular catheter infections since the recent reviews. Many factors have been shown to affect the risk of catheters becoming infected. These include the unique abilities of certain organisms, Staphylococcus epidermidis, Staphylococcus aureus, and Candida albicans, to cause catheter-related infections. Molecular typing studies increasingly are improving our understanding of the pathogenesis of S. epidermidis/CoNS catheter-related infection. Recent studies with isogenic S. epidermidis mutants increasingly suggest that production of a polysaccharide adhesin is crucial to the pathogenesis of foreign-body infection. This polysaccharide, first named PS/A, was initially described as a virulence factor in association with work examining the pathogenesis of endocarditis. Two additional findings of relevance to the pathogenesis of endocarditis and possibly vascular catheter infections are that binding to platelets facilitates endocarditis and S. aureus strains causing endocarditis are much more likely to be resistant to platelet microbicidal proteins. The pathogenesis of catheter-related thrombosis has been studied in greater depth in recent years. With peripheral catheters, ultrasonographic imaging has shown that early thrombus formation (<24 h after insertion) occurs near the site of insertion, whereas later thrombus formation (>24 h after insertion) occurs near the catheter tip. Recent in vitro studies have shown that surface manipulations of polyurethane can lead to differences in protein and platelet deposition with associated differences in bacterial adherence.
This chapter focuses on arterial prosthetic infections. In two reviews of the literature done in 1983 and 1992, the overall incidence of graft infection was estimated to be about 2%. When looking at the distribution of microorganisms according to the site of graft implantation three points deserve mention. First, intestinal microorganisms appear responsible for most aortoiliac infections when no groin incision has been done. Second, S. epidermidis is now the leading pathogen after aortofemoral reconstruction. Third, S. aureus remains the principal pathogen in most series after infrainguinal reconstructions. The majority of patients with an early infection of a superficial prosthesis will present overt signs of infections, such as an inflammatory perigraft mass, an abscess, a draining sinus tract, a palpable anastomotic pseudoaneurysm, or an exposed graft. The occurrence of ‘’true’’ failures of correctly administered prophylaxis reported with cephalosporins, that is, the occurrence of an infection due to microorganisms sensitive to the administered antibiotic, and the increased role of gram-negative bacteria leave room for debate regarding the choice of prophylactic antibiotics. However, this discussion is difficult because many questions remain unanswered about the physiopathology of vascular graft infection and the mechanisms of the prophylactic activity of antibiotics. The authors demonstrated that rifampin-bonded gelatin-sealed grafts were resistant to infection when used for in situ replacement of a graft by S. epidermidis. In this study, conducted in 2,610 patients in 90 centers, the incidence of wound infection was significantly reduced in patients receiving a rifampin-bonded graft in association with perioperative systemic antimicrobial prophylaxis.
Prosthetic valve endocarditis (PVE) occurs in 1 to 9.4% of valve recipients. The PVE studies that were reviewed often lacked comprehensive follow-up information on operated patients and thus may have failed to account for infections that were not treated at the reporting institution. Calderwood et al. found 116 patients with PVE in 2,608 patients that survived valve replacement surgery done from January 1975 through December 1982. Actuarial estimates of cumulative risks in this study were 3.1% at 12 months and 5.7% at 60 months. The increasing incidence of PVE on bioprosthetic valves with time elapsed after the initial postoperative year, combined with the leaflet localization of those late onset infections, suggests that anatomic changes in bioprosthetic valve leaflets over time may increase the susceptibility of these valves to endocarditis. Suspecting that the pathogenesis of some infections would relate to nosocomial events, particularly those occurring during or shortly after surgery, Block et al. coined the term “early PVE” for patients with onset of infection within 60 days of surgery. Cefamandole was more effective than cefazolin in preventing wound infections, particularly those caused by Staphylococcus aureus, in cardiac surgery patients. In one randomized double-blind trial, patients undergoing cardiac or major vascular surgery who received vancomycin experienced fewer surgical wound infections than did those who received cefazolin or cefamandole. However, in this study there was no significant difference in surgical wound infection rates between recipients of the various prophylactic antibiotic regimens when one considered patients undergoing cardiac surgery.
Prosthetic joint implantation is among the most remarkable advances in surgery and medicine to occur during the last three decades. Five hundred seventy-eight cases of total hip and total knee prosthetic arthroplasty infections seen at the Mayo Clinic between 1992 and 1997 were classified as definite infections according to a strict case definition. The clinical presentation of prosthetic joint infection is highly variable, ranging from the syndrome of acute septic arthritis with the sudden onset of joint pain, erythema, swelling, fever, and systemic symptoms to a syndrome of indolent loosening and chronic pain, which is difficult to distinguish from aseptic loosening on the basis of symptoms and clinical examination alone. This chapter discusses the utility of various diagnostic tests used to diagnose prosthetic joint infection. For patients undergoing revision total joint arthroplasty, pathological examination of intraoperative frozen sections is useful in selected cases to detect infection. Antimicrobial therapy without concomitant surgical intervention is not considered standard therapy for prosthetic joint infection. The oral antibiotic used for chronic suppression should be chosen based on susceptibility test results, long-term tolerability, and cost. Antimicrobial prophylaxis has been utilized traditionally in operative procedures that have a high rate of postoperative wound infection, when foreign materials must be implanted, or in operative procedures in which the wound infection rate is low but the development of a wound infection would result in a catastrophic event.
This chapter talks about a new diagnostic and therapeutic approach based on the ambulatory management of infections to minimize the social consequences for the patient and the important economic impact for the community. Coagulase-negative staphylococci, streptococci, gram-negative aerobes, and anaerobes are the most common bacteria in late-onset prosthetic joint infections. Infections within the first few months of surgery usually present with pain, erythema, and drainage at the wound site. The combination of fleroxacin with rifampin resulted in a 41% cure rate in an Staphylococcus aureus foreign-body infection model. The addition of vancomycin to the fleroxacin-rifampin combination significantly increased the cure rate and the rapidity of sterilization of the foreign body. Fusidic acid can accumulate within cells, demonstrated by the fact that 7- to 10-fold intracellular compared with extracellular concentrations have been measured in human polymorphonuclear leukocytes and lymphocytes. The only antibiotics remaining active against multiresistant staphylococci and able to diffuse into the bone tissue are glycopeptides (vancomycin and teicoplanin) and co-trimoxazole. Bone marrow changes occur in patients with preexisting depleted folate stores and one recent report established that bone marrow changes occur in one case per 18,000 prescriptions. Ciprofloxacin has an excellent penetration into bone and an excellent MIC for Pseudomonas aeruginosa. Ciprofloxacin alone is effective in the treatment of P. aeruginosa osteomyelitis. Salvage of infected orthopedic implants by appropriate antimicrobial strategies is feasible and the ambulatory management of such infections contributes to humanization of therapy.
Cerebrospinal fluid (CSF) shunt infections may lead to ventriculitis, ventricular compartmentalization, and cortical mantle thinning, as well as meningitis, subdural empyema, and seizures. In addition, shunt infections have been shown to increase mental retardation and deterioration of mental capacity. The manifestations of central nervous system (CNS) shunt infections are variable. The most common presentation is a nonspecific one consisting of mild fever, nausea, vomiting, malaise, or signs of increased intracranial pressure (ICP) such as headache or altered consciousness. A unique complication of patients with ventriculovascular shunts is the development of shunt nephritis, a form of acute glomerulonephritis. In the majority of these cases the infecting organism has been Staphylococcus epidermidis, but other bacteria such as corynebacteria can cause this complication. The choice of antimicrobial therapy must be individualized, depending upon the clinical appearance of the patient, cerebrospinal fluid findings, and local patterns of antimicrobial susceptibility. A wide variety of choices is available for treatment of gram-negative shunt infections. A number of expanded-spectrum cephalosporins (e.g. cefotaxime, ceftriaxone, and ceftazidime) achieve therapeutic concentrations in the cerebrospinal fluid (CSF) and ventricular fluid after intravenous administration in patients with inflamed meninges. Some experts prefer to treat CNS shunt infections with both systemic and intraventricular antibiotics because of patient-to-patient variability in antibiotic concentrations achieved in ventricular fluid after intravenous therapy alone.
This chapter discusses infections related to pacemakers (PMs) or implantable cardioverter defibrillators (ICDs) are major complications and are difficult to manage; complete removal of the device is required in a majority of cases. Many factors such as diabetes, underlying malignancy, corticosteroids, anticoagulation, and advanced age have been suspected as potential predisposing factors for developing a device-related infection, but only some of them can nowadays be considered as well characterized independent risk factors. The diagnosis of a device-related infection can be difficult to establish. The clinical presentation depends on many variables, including the site of infection (the pulse-generator pocket and/or the conducting system), the type of electrode implanted (epicardial or intraventricular transvenous), the route of contamination (erosion, wound or pocket infection, secondary to a bacteremia, or contiguous spread from an adjacent infectious focus), and the microorganism involved. In summary, the diagnosis of an implanted device-related infection must be suspected in the presence of any erosion of an implanted device, chronic fever without documented infectious foci, multiple pulmonary infiltrates or emboli, and/or persistent or relapsing evidence of infection at the insertion site. Despite strong microbiological and epidemiological data suggesting that local contamination with the flora present in the skin appendages might contaminate the wound margin during the surgical procedure and be responsible for a majority of device-related infections, systemic antibiotic prophylaxis has remained controversial. Almost all authors report the necessity for assiduous skin disinfection before surgery, and others employ intrapocket antibiotic spray or instillation before insertion.
Over the last quarter of a century, the use of intrauterine devices (lUDs) and tampons by millions of women worldwide has introduced four previously rare and unrecognized infections. The morbidity and mortality associated with toxic shock syndrome (TSS), spontaneous septic midtrimester abortion, pelvic actinomycosis, and lUD-associated pelvic inflammatory disease (PID) have been significant. These events have focused badly needed attention on the composition of these devices and pathogenesis of these infections. Initial insertion of the IUD is associated with bacterial colonization of the normally sterile uterine cavity. The sterile-foreignbody- induced inflammation may persist in both the endometrium and the endosalpinx, as demonstrated by histopathology and the presence of neutrophils and macrophages in uterine washes. The upper genital tract is normally sterile since the cervix provides an effective physical and chemical barrier to bacteria. The closed internal os, resistant squamous epithelium, and bacteriostatic endocervical mucus maintain the barrier. A recent prospective controlled study confirmed that infectious complications of IUDs are more frequent if the threads lead from the uterine cavity to the vagina than if they are contained within the uterine cavity. As for many other postoperative cases of TSS, most of these cases may have been secondary to wound infections.
Ocular infections attributed to foreign bodies may be categorized by the anatomic location of the infection. This chapter concentrates on microbial keratitis secondary to contact-lens use and endophthalmitis after surgical or traumatic perforation of the eye. Foreign-body-associated lid and orbit infections are mainly secondary to trauma. The diameter and configuration of the infection, its relationship to the visual axis, its depth in the cornea, and the presence of associated eye conditions should be noted, and if possible, photography should be performed. Corneal scrapings for cultures are required for precise microbiologic diagnosis. The overwhelming risk factor for microbial keratitis among lens wearers is overnight wear. Given current contact-lens technology, the most effective way to reduce the incidence of infections is to discourage overnight wear of lenses. Any contact-lens-wearing subject who experiences the acute onset of ocular pain, decreased vision, and a red eye should remove the lens and seek ophthalmologic attention promptly. As opposed to infections in contact with a prosthesis elsewhere in the body that usually require removal of the prosthesis for sterilization, in cases of acute endophthalmitis following cataract surgery there is no evidence to support the notion that the intraocular lens (IOL) should be removed. Oral fluconazole (800 mg or more) may be efficacious as a long-term follow-up antibiotic for Candida endophthalmitis. Some surgeons add antibiotic (e.g., vancomycin) to the intraocular injected solutions used during cataract surgery.
Bacterial infection is the most common cause of excess morbidity and mortality in patients who require endotracheal intubation or tracheostomy. The normal lung is sterile distal to the central carina, despite the daily inoculation of bacteria. Aspiration of liquids is prevented by reflex closure of the glottis following stimulation of receptors in the larynx and trachea and by the vigorous coughing that such stimulation evokes. Impairment of mucociliary function and mucus hypersecretion leads to pooling of secretions in the airways of intubated patients. Bacteria presented to the lung in a liquid bolus, such as contaminated upper-airway secretions, are cleared more slowly than bacteria presented as aerosols. Colonization by gram-negative bacilli (GNB) and other cextends to multiple contiguous sites including the oropharynx, endotracheal tube, tracheobronchial secretions, and stomach. Tracheobronchitis can be diagnosed when secretions become purulent, usually associated with an increased volume, viscosity, or both, with no new infiltrates visible on the chest radiograph. Tracheobronchitis frequently precedes nosocomial pneumonia in patients with endotracheal tubes or tracheostomies. Respiratory infection in patients with artificial airways is a dynamic process with virtually continuous inoculation of the airways with a changing bacterial flora, most of which is contained by lung defenses but with varying degrees of resultant inflammation. Sinusitis is clearly associated with an increased risk of nosocomial pneumonia, presumably due to the likelihood of aspiration of grossly infected material into the distal airways.
Outside of the urinary tract, foreign bodies that are implanted (such as pacemakers, central nervous system shunts, heart valves, and joints) usually remain uninfected. Urinary tract infection is the most common nosocomial infection in the United States, and the vast majority of such cases are the result of bladder catheterization. Other less common foreign-body infections in the urinary tract involve prosthetic devices such as stents, bladder sphincters, and penile implants. The diagnosis of catheter-related urinary tract infection is based on both clinical and laboratory information. Bladder catheterization is by far the most common situation in which infection associated with a foreign body occurs in the urinary tract. Complications of bladder catheterization are relatively frequent and may be serious. Urinary tract stones are a common problem in patients with chronic indwelling catheters and may occur in part as a result of chronic or repeated infections with urease-splitting organisms such as Proteus species. The frequency of symptomatic urinary tract infections in patients with ureteral stents varies greatly.
Hemodialysis and peritoneal dialysis provide life-sustaining therapy for patients with end-stage renal disease (ESRD). Peritoneal dialysis requires the regular exchange of dialysate within the peritoneum. The dialysate contains high concentrations of glucose, which create an osmotic force to move fluid into the peritoneal cavity. Immunosuppression can also be a direct result of the dialysis process. During peritoneal dialysis, the regular exchange of dialysate causes the dilution and removal of white cells, along with factors such as cytokines, immunoglobulins, and opsonins. The standard material for the construction of bridge grafts is polytetrafluoroethylene (PTFE). PTFE is hydrophobic, inert, and thought to resist infection. Central venous catheters (CVCs) play a vital role in the maintenance of vascular access for many patients. Tunneling and dacron cuffs are designed to prevent infection of hemodialysis CVCs. Empiric treatment of catheter-related bloodstream infection (CR-BSI) should cover gram-positive (e.g., vancomycin, cefazolin, cloxacillin) and gram-negative (e.g., gentamicin) organisms while awaiting culture results. Vancomycin should be used if the prevalence of methicillin-resistant staphylococci is high. Blood cultures should be repeated periodically during and immediately after completion of therapy to monitor effectiveness. Infections related to peritoneal dialysis are broadly classified as peritonitis or exit-site/ tunnel infection. Peritonitis caused by pseudomonal or xanthomonal organisms is generally more serious than that caused by other gram-negative bacteria. Catheter loss has been reported to complicate 16.3% of episodes of peritonitis and 21% of exit-site and tunnel infections.
In the beginning, the clinical evaluation of osscointegrated implants comprised primarily edentulous patients, suffering mostly from advanced atrophy of the osseous alveolar ridge as a consequence of tooth loss. During the last decade, the clinical use of osseointegrated dental implants has also been extended to partially dentate patients, addressing distally shortened dental arches and extended edentulous gaps, as well as single missing teeth, involving both the maxilla and the mandible. Single-tooth replacement with dental implants has recently become an increasingly applied treatment option, even in the esthetically sensitive anterior maxilla, and the few prospective studies available to date have reported favorable results. A recent study reported that out of 1,352 placed implants, 1,147 concerned partially dentate patients. As they are widely used in sites of limited bone height but high levels of occlusal load, distinctly increased requirements comprising both quality of osseointegration and biomechanical properties of the fixture-abutment complex itself are currently associated with dental implants. Osseointegrated dental implants or their secondary prosthetic components are in direct contact with the complex oral ecosystem, comprising fluids and high concentrations of various microbiota. Depending on the respective continuing diagnosis during the maintenance phase, developing peri-implant lesions should be intercepted as early as possible and treated according to the principles of the cumulative interceptive supportive therapy (CIST) protocols. Promising reports related to novel preventive and therapeutic approaches and concepts, including regenerative procedures and tissue engineering, indicate that dental implant therapy will continue to evolve as a highly effective and predictable treatment modality.
The administration of antimicrobial agents prophylactically during the perioperative period has become standard practice for surgical procedures involving the implantation of prosthetic material, and most authorities in the field of surgical wound prophylaxis have endorsed this practice. A recent meta-analysis of nine randomized, controlled studies involving 1,045 patients undergoing placement of ventricular shunts suggested that antimicrobial prophylaxis reduced infection risk twofold, but was of apparent benefit only if infection rates in the control group were greater than 5%. While clinical studies verifying that perioperative antibiotics significantly reduce implant infection rates are not available for the majority of such procedures, significant benefits frequently have been demonstrated when infections within any part of the surgical incision, not just the prosthetic device, are included in the evaluation. Although these differences did not achieve statistical significance because of the paucity of infections observed in either group, the authors advocated the three-dose regimen pending more definitive data. In prophylaxis of prosthetic valve endocarditis, however, anecdotal associations between episodes of transient bacteremia and endocarditis have led to an almost universal recommendation for aggressive antimicrobial prophylaxis for patients with prosthetic valves who undergo dental procedures and surgery. The choice of an antimicrobial regimen and the duration of use remain matters of great confusion. When recurrent pathogens are encountered, a systematic evaluation of new prophylactic regimens, possibly in the form of ongoing randomized trials, may provide a database for a rational approach to infection prevention in implantation surgery.
Millions of intravascular catheters are purchased each year by hospitals and clinics, placing many patients at risk for serious catheter-related infections. This chapter summarizes the rapidly expanding body of literature concerning prevention of intravascular catheter-related infections in the hope of reducing the risk posed to present and future patients. Prophylaxis with vancomycin or teicoplanin during central venous catheter insertion does not reduce the incidence of catheter-related bloodstream infection. The addition of prophylactic vancomycin to flush solutions or total parenteral nutrition solutions significantly reduces the incidence of catheter-related bloodstream infection; however, use of systemic antimicrobial agents to prevent intravascular catheter-related infections is not recommended. Administering very low doses of warfarin reduces thrombosis due to long-term central venous catheters. Use of prophylactic heparin by bolus infusion or when it is added to intravenous solutions does not significantly reduce the risk of central venous catheter-related bloodstream infection. Prophylactic heparin significantly reduces the incidence of catheter-related central venous thrombosis in patients with central venous and pulmonary artery catheters. A number of different strategies can be used to prevent serious intravascular catheter-related infections.
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Infections Associated with Indwelling Medical Devices, Third Edition
This second edition provides an all-encompassing presentation of the microbiologic, biorheologic, and clinical solutions that underlie the biomechanic development of infections in patients with prosthetic devices or foreign bodies.
Purpose
It is intended to provide a scientific basis and rationale for understanding these stubborn infections and offer a broad substrate of basic microbiological and physical data from which further studies can be devised.
Audience
It is intended to provide a scientific basis and rationale for understanding these stubborn infections and offer a broad substrate of basic microbiological and physical data from which further studies can be devised.
Feature
This is a worthy contribution to the somewhat splintered literature on infections associated with indwelling medical devices. It brings together in one volume basic and clinical investigators who have made valuable contributions to the field, a description of the biomechanics and rheology that is unique to infections with these devices, and also provides excellent clinical insights by established clinicians on the clinical syndromes that result from the use of prosthetics in human medicine. The chapter on "Infections Caused by Intravascular Devices Used for Infusion Therapy" is especially good. It has several very worthy graphic features. The photo illustrations are of excellent quality and include scanning electron micrographs with pedagogic value, not just theatrical interest. The tables and charts are concise, valuable, and supplement the text. There are several color photographs of excellent quality. The overall appearance of this book is quite above average. The only deficiency, and it is minor, is a less than complete index that will force the reader to do more general reading within a chapter to find a specific topic of interest. Because almost all the chapters in this book are outstanding, this probably has some hidden benefits!
Assess
This book is highly recommended to infectious disease and critical care practitioners. I also believe that it would be a unique way for bioengineers to gain an appropriate clinical perspective to this serious problem, the solution to which, ironically, rests with them and not with physicians.
Reviewer: John A. Robinson, MD (Loyola University Stritch School of Medicine)