Infectious Diseases in an Age of Change The Impact of Human Ecology and Behavior on Disease Transmission (1995) / Chapter Skim
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Hospital-Acquired Infections: Diseases with Increasingly Limited Therapies
Hospital-Acquired Infections: Diseases with Increasingly Limited Therapies
Pages 113-134
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From page 113... ...
Modern acute-care hospitals are complex institutions consisting of a variety of specialized components: burn services, oncology wards, coronary care units, intensive care units, and transplantation units. Individual units may have particular nosocomial infection problems related to the type of patient being treated or the nature of their underlying illnesses, procedures employed in individual units, and the selection pressure exerted by antimicrobial usage patterns.
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From page 114... ...
Currently, an estimated 46,00058,000 prosthetic heart valve replacement procedures are performed annually in the United States (6~. The first saphenous vein aortocoronary artery bypass graft for coronary artery disease was carried out in 1967.
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From page 115... ...
These include the extensive nature of the surgical procedures, prolonged operative/anesthesia times, need for medical devices and invasive manipulations during the post-operative period, the often complex nature of the underlying disease or of associated illnesses, and the older ages of hospitalized patients. Overall nosocomial infection rates vary considerably depending on the type of surgery performed.
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From page 116... ...
aureus isolates at Boston City Hospital prior to 1946 were susceptible to penicillin, by 1952 ~75% of isolates were resistant (13~. In the early 1970s, ~75% of S
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From page 117... ...
The introduction of penicillin in treatment of human infections was followed in a few years by the introduction of streptomycin, the tetracyclines, erythromycin, and chloramphenicol. As more extensive surgery and cytotoxic drugs were used in treatment and as selection of more antibiotic-resistant microorganisms developed as a result of broadspectrum antibiotic usage, the frequency of hospital-acquired infections increased.
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From page 118... ...
The higher rates in the large teaching hospitals presumably reflect the more seriously ill patient population within large tertiary-care hospitals. Increases in the primary bloodstream infection rates occurred between 1980 and 1989 and varied by category from 70 to 279%.
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From page 119... ...
in bloodstream bacterial infections occurred with CNS in large teaching hospitals. Bloodstream infections with Candida spp.
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From page 120... ...
aureus isolates reveals marked differences between countries: 0.1% in Denmark in 1988, 4% in Germany in 1989, 26% in France in 1989, and 15% in the United States in 1987-88. However, these represent mean prevalence rates for many hospitals.
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From page 121... ...
Important factors in the control of the Danish outbreak included the extensive and continual monitoring of nosocomial S aureus isolates and prompt institution of isolation precautions when MRSA was detected.
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From page 122... ...
N SWARTZ prosthetic devices (artificial heart valves, cardiac pacemaker leads, joint replacements, nervous system ventricular shunts, peritoneal dialysis catheters, and polyethylene intravenous catheters)
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From page 123... ...
In the 1970s, ~50% of antimicrobial usage involved administration to hospitalized patients. Study of parenteral antimicrobial usage at the University of Iowa Hospital between 1978 and 1992 provides an indication of changes that have occurred in major teaching hospitals (37~.
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From page 124... ...
The bactericidal action of this combination is due to limited penicillin inhibition of bacterial cell wall synthesis that permits enhanced uptake of aminoglycoside, the latter then acting lethally on its ribosomal target (40~. Treatment of serious enterococcal infections has involved the use of combined penicillinaminoglycoside therapy since the 1950s.
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From page 125... ...
Although penicillin resistance due to ,l3 lactamase production is as yet uncommon in enterococci, it presents a major threat, particularly if conjugative spread occurs. Vancomycin resistance among clinical enterococcal isolates, particularly E
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From page 126... ...
N SWARTZ vancomycin resistance has been found in isolates from patients with nosocomial infections in intensive care units where the percentage rose from 0.4% in 1989 to 13.6% in 1993.
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From page 127... ...
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From page 128... ...
Inherent resistance to vancomycin is a feature of Leuconostoc spp., Pediococcus spp., and Lactobacillus spp., all three rarely causing human infections. A threat exists of further dissemination of vancomycin resistance to other species via transposition of Tnl546 into broad-host-range plasmids.
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From page 129... ...
Enterobacteriaceae producing extended-spectrum ,B-lactamases have been responsible for a number of nosocomial outbreaks, usually originating in an intensive care unit and then spreading elsewhere (56~. Such dissemination of drug resistance can involve spread of a particular strain of bacteria, horizontal interspecies spread of a resistance plasmid, or spread of resistance genes.
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From page 130... ...
and polymyxin. The above-described sequential outbreaks of nosocomial infections due to increasingly resistant organisms emphasizes the potentially great selective power of extensive antimicrobial use in a given institution, particularly in intensive care units, in favoring emergence of multiresistant pathogens.
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From page 131... ...
A variety of factors contribute: increasing age of patients; availability, for treatment of formerly untreatable diseases, of extensive surgical and intensive medical therapies; and frequent use of antimicrobial drugs capable of selecting a resistant microbial flora. Nosocomial infections due to resistant organisms have been a problem ever since infections due to penicillinase-producing Staphylococcus aureus were noted within a few years of the introduction of penicillin.
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From page 132... ...
prompt institution of barrier precautions when infected or colonized patients are identified, and (iii) appropriate use of antimicrobials through implementation of antibiotic control programs.
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From page 133... ...
l. & the National Nosocomial Infections Surveil lance System (1992)
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