By S. Hogar. Washington & Jefferson College.
Change scrub suits that are visibly soiled or contaminated by blood or other potentially infectious materials best 250mcg fluticasone. Asepsis and surgical technique Level I: Adhere to principles of asepsis when placing intravascular devices or when dispensing or administering intravenous drugs order fluticasone 250 mcg amex. Use delayed primary skin closure or allow incisions to heal by secondary intention if the surgical site is contaminated or dirty order fluticasone 250 mcg with mastercard. Use closed suction drains when drainage is necessary fluticasone 500mcg overnight delivery, placing the drain through a separate incision distant from the operative incision. Wash hands before and after dressing changes and any contact with the surgical site. Educate the patient about surgical site infections, relevant symptoms and signs, and the need to report them if noted. Additional studies that are frequently ordered include a urinalysis, urine pregnancy test, and, when indicated, liver function studies. While the list of additional studies could go on and on, the important principle to understand is that few of these studies are helpful when routinely ordered. Selective laboratory evaluation, coupled with a thorough history and physical exam, will prove to be both safer and more cost-effective. Imaging Studies The disease process being treated should dictate the imaging studies ordered. Most patients can be brought to the operating room safely based on the performance of good history and physical exam. Diagnostic imaging studies should be ordered to ﬁne-tune the history and physical and so that appropriate surgical planning decisions can be made. This routine order is somewhat historical, carrying over from the days of prevalent tuber- culosis. Healthy young patients with no evidence of pulmonary disease beneﬁt little from a chest x-ray. It is rare in a patient who has a normal pulmonary exam that the chest x-ray signiﬁcantly alters the operation for which it was ordered. It is more reasonable to obtain a chest x-ray in an elderly patient, and, at times, this results in interesting ﬁndings, such as a lesion requiring further workup. Perioperative Care of the Surgery Patient 17 Informed Consent Informed consent should be viewed as an opportunity for the surgeon to take some time to explain to the patient why an operation is necessary, what the operation entails, what sort of recovery to expect, and what complications might be incurred. The discussion should be frank and honest while sensitive to obvious anxieties of the preoperative patient. It is also helpful, when possible, to have this discussion in the presence of a concerned spouse or family member. With this in mind, the discussion may best be done sometime well in advance of the operation. The discus- sion, when possible, also should include nonoperative therapies for the given disease process. Case Evaluation When considering the approach to the surgical patient as it applies to the case cited at the beginning of this chapter, there are several impor- tant considerations. First, the patient most likely does have a surgical problem and most likely requires an operation. He most likely does not require an emergency operation, and therefore the physicians attend- ing to the patient have some time to fully evaluate the problem with an appropriate series of laboratory tests and diagnostic studies. A thorough and honest assessment of the patient’s comorbid conditions and risks for major surgery is necessary prior to proceeding with a signiﬁcant operation. Summary The successful approach to the surgical patient requires the physician to understand the anatomic and physiologic problems with which the patient presents, listen to the patient, collect a detailed history, and then perform a complete physical exam. Based on the history and physical, a diagnosis, or at least a working differential diagnosis, is derived. Although the aforementioned steps are not unique to surgery, the dif- ference lies in the fact that a surgeon undertakes the aforementioned steps en route to an intervention. The intervention may be minor and expose the patient to minimal risk or it may be very signiﬁcant and may permanently alter the patient’s life. To earn that trust, surgeons must be well trained, exhibit good judgment, understand the limitations of their patients based on their comorbidities, and understand the limitations of their own ability. Development and validation of a multifactorial risk index for predicting postoperative pneumonia after major noncardiac surgery. Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee on Perioperative Cardiovascular Evaluation for Noncardiac Surgery). History of present illness: Three days ago, when lifting a very large pine tree that blew over in a recent windstorm, the patient felt a sudden pain in his left groin. The acute pain resolved, but he continues to feel a “dragging” sensation in same area. Review of systems: Noncontributory: • Gastrointestinal: Denies change in bowel habits; no history of con- stipation; no hematochezia; no nausea and vomiting. Nackman Pertinent social/family history: Non–union worker who loads and unloads delivery trucks. Upon standing, a bulge observed in left inguinal region: no erythema, nontender, easily reduced. The Relevance of Evidence-Based Medicine Many of the issues involved in the care of patients include “age-old” traditions that may be based on empiricism. Until several decades ago, drainage of the gall- bladder bed following cholecystectomy was the standard of care and was based on the belief that drainage of the affected area would promote healing and reduce postoperative complications. Through the 1970s, students and residents heard from their instructors and super- visors: “This is how my mentor taught me to drain the gallbladder bed, so you should do it this way, too. Even though the traditional dogma had been rebuked by demonstrating no need for routine drainage, the clinical practice took decades to change. A signiﬁcant challenge in medicine is to maintain the learning process throughout one’s career, to keep current with the most recent evidence and practice guidelines, to understand the science behind the evidence and the guidelines, and thereby to continue providing optimal patient care. Even seasoned clinicians, when faced with the need to make a complex clinical decision, ask: “What are the practice guidelines for treating patients with this disease? It is important to understand the studies that resulted in the practice guidelines and the implications of these ﬁndings for your speciﬁc patient. Remaining current with important developments and thoughtfully integrating new information into your patient’s care are essential elements of the practice of surgery, whether one is a student, resident, or an experi- enced attending physician. Evidence-based medicine is the purpose- ful integration of the most recent, best evidence into the daily practice of medicine (See Algorithm 2. The practice of evidence-based medicine means integrating individual clinical expertise with the best avail- able clinical evidence from systematic research. Practicing Evidence-Based Surgery 21 Begin Here: Proceed Determine to Next Diagnosis Patient Problem Provide Care of Review Estimate Highest Quality the Prognosis Evidence Determine Decide Harm Best Therapy Algorithm 2. Without clinical expertise, practice risks becoming tyrannized by external evidence, for even excellent external evidence may be inapplicable to or inappropriate for an individual patient. Without current best external evidence, practice risks becoming rapidly out of date, to the detriment of the patients. Further, “best evidence” refers to the data and the conclusions derived from systematic research, such as infor- mation provided through the Cochrane Library (http://www. However, current best evidence must be integrated with clinical acumen (derived from experience, expert opinion, and anecdotal evidence) and with the preferences and values of the patient. Nackman Patients with a similar disease process may vary in their presenta- tion and in their response to treatment. Therefore, it is essential to realize that, even with the best evidence, the application of that evi- dence must be considered in the context of the unique attributes of each patient. Further, patient autonomy, as expressed in differences in expec- tations and preferences, must be considered when developing a patient management plan. First, a common characteristic of physicians is their desire and obligation to provide optimal care for their patients and, as much as is possible, to facilitate the patients’ return to their previous state of health. Since optimal medical care for patients changes over time with progress in technology and improved understanding of patient outcomes, it is necessary to have the tools that ensure your ability to remain current. Evidence-based medicine provides a framework to allow the physician lifelong learning opportunities. Second, today’s patients are better educated and often seek a collab- orative relationship with their physician.
This element bears the genetic information buy 500 mcg fluticasone amex, the structural genes for the structural proteins as well as for other proteins (enzymes) re- quired to produce new phage particles order fluticasone 500 mcg free shipping. Attachment to cell surface involving specific interactions be- tween a phage protein at the end of the tail and a bacterial receptor generic 100mcg fluticasone amex. Lysis occurs by a phage-encoded murein hydrolase best fluticasone 100mcg, which gains access to the murein through membrane channels 3 formed by the phage-en- coded protein holin. Enzymatic penetration of the wall by the tail tube tip and injection of the nucleic acid through the tail tube. Beginning with synthesis of early proteins (zero to two minutes after injection), e. Then follows transcription of the late genes that code for the structural proteins of the head and tail. The new phage particles are assembled in a maturation process toward the end of the reproduction cycle. This step usually follows the lysis of the host cell with the help of murein hydrolase coded bya phage gene that destroys the cell wall (Fig. Depending on the phage species and milieu conditions, a phage reproduction cycle takes from 20 to 60 minutes. This is called the latency period, and can be considered as analogous to the generation time of bacteria. Depending on the phage species, an infected cell releases from 20 to several hundred new phages, which number defines the burst size. In view of this fact, one might wonder how any bacteria have survived in nature at all. It is important not to forget that cell population density is a major factor determining the probability of finding a host cell in the first place and that such densities are relatively small in nature. Another aspect is that only a small proportion of phages reproduce solely by means of these lytic or vegetative processes. Following injection of the phage genome, it is integrated into the chromosome by means of region-spe- cific recombination employing an integrase. Cells carrying a prophage are called lysogenic because they contain the genetic information for lysis. It prevents immediate host cell lysis, but also ensures that the phage genome replicates concurrently with host cell reproduction. Lysogenic conversion is when the phage genome lysogenizing a cell bears a gene (or several genes) that codes for bacterial rather than viral processes. Genes localized on phage genomes include the gene for diphtheria toxin, the gene for the pyrogenic toxins of group A streptococci and the cholera toxin gene. Ad- ministration of suitable phage mixtures in therapy and prevention of gastrointestinal infections. Recognition of the bacterial strain responsible for an epidemic, making it possible to follow up the chain of infection and identify the infection sources. The Principles of Antibiotic Therapy 187 The Principles of Antibiotic Therapy & Specific antibacterial therapy refers to treatment of infections with anti- infective agents directed against the infecting pathogen. The most important group of anti-infective agents are the antibiotics, which are products of fungi and bacteria (Streptomycetes). Anti-infective agents are categorized as having a broad, narrow, or medium spectrum of action. The efficacy, or effectiveness, of a substance refers to its bactericidal or bacteriostatic effect. Under the influence of sulfonamides and trimethoprim, bacteria do not synthesize sufficient amounts of tetrahydrofolic acid. Due to their genetic variability, bacteria may devel- op resistance to specific anti-infective agents. The most important resistance mechanisms are: inactivating enzymes, resistant target molecules, reduced influx, increased efflux. Resistant strains (problematic bacteria) occur fre- quently among hospital flora, mainly Enterobacteriaceae, pseudomonads, staphylococci, and enterococci. The disk test is a semiquantitative test used to classify the test bacteria as resistant or susceptible. In combination therapies it must be remembered that the interactions of two or more antibiotics can give rise to an antagonistic effect. Surgical chemoprophylaxis must be administered as a short-term anti- microbial treatment only. One feature of these pharmaceuticals is “selective toxicity,” that is, they act upon bacteria at very low concentration levels without causing damage to the macroorganism. These natural substances are produced by fungi or bacteria (usually Streptomycetes). The term “anti- biotic” is often used in medical contexts to refer to all antibacterial pharma- ceuticals, not just to antibiotics in this narrower sense. The most important groups (cephalosporins, penicillins, 4-quinolones, macrolides, tetracyclines) are in bold print. Pseudomonas; labile against Gram-positive and Gram-negative penicillinases temocillin (6-a-methoxy No effect against Pseudomonas; highly stable in the ticarcillin) presence of betalactamases Acylureidopenicillins azlocillin, mezlocillin, Effective against Enterobacteriaceae and piperacillin, apalcillin Pseudomonas; despite lability against beta- lactamases active against many enzyme-producing strains due to good penetration and high levels of sensitivity of the target molecules Penems Penicillins with a double bond in the second ring system A carbapenem (C atom instead of sulfur in second N-formimidoyl thienamycin ring); very broad spectrum and high level of (imipenem = activity against Gram-positive and Gram-negative N-F-thienamycin + bacteria, including anaerobes; frequently effective cilastatin) against Enterobacteriaceae and Pseudomonas with resistance to the cephalosporins of Group 3b; inactivated by renal enzymes; is therefore administered in combination with the enzyme inhibitor cilastatin Kayser, Medical Microbiology © 2005 Thieme All rights reserved. Sulfones dapsone diaminodiphenylsulfone; for therapy of leprosy Tetracyclines doxycycline tetracycline, Broad spectrum including all bacteria, chlamydias, oxytetracycline, and rickettsias; resistance frequent; dental deposits rolitetracycline, minocycline in small children Kayser, Medical Microbiology © 2005 Thieme All rights reserved. Most, however, have broad spectra like tetracyclines, which affect all eubacteria. Many substances can develop both forms of efficacy depending on their concentration, the type of organism, and the growth phase. After the anti-infective agent is no longer present, the bacterial cells not killed require a recovery phase before they can reproduce again. A bacteriostatic agent alone can never completely eliminate pathogenic bacteria from the body’s tissues. In tissues in which this defense system is inefficient (endocardium), in the middle of a purulent lesion where no functional pha- gocytes are present, or in immunocompromised patients, bactericidal sub- stances must be required. The clinical value of knowing whether an antibac- terial drug is bacteriostatic or bactericidal is readily apparent. All of the bacteria from an infection focus cannot be eliminated without support from the body’s immune defense system. A bacterial population always includes several cells with phenotypic resistance that is not geno- typically founded. These are the so-called persisters, which occur in in-vitro cultures at frequencies ranging from 1:106 to 1:108 (Fig. The cause of such persistence is usually a specific metabolic property of these bacteria that prevents bactericidal substances from killing them. Infections with L-forms show a special type of persistence when treated with antibiotics that block murein synthesis (p. The Principles of Antibiotic Therapy 197 Efficacy of Selected AntI-Infective Agents Betalactams Amino- glycosides Sulfonamides Tetracyclines Betalactams, 3 aminoglycosi- des Persisters Time (hours) Fig. Betalactams are bactericidal only during the bacterial cell division phase, whereas aminoglycosides show this activity in all growth phases. Some cells in every culture (so-called persisters) are phenotypically (but not genotypically) resistant to the bactericidal effects of anti-infective agents. The combination of sulfamethoxazole and trimethoprim (cotrimoxazole) results in a po- tentiated efficacy. They probably hold in similar form for other betalactams and other bacteria as well. These enzymes create gaps in the murein sac- culus while the bacterium is growing, these gaps are then filled in with new murein materi- al. Bacteria the growth of which is inhibited, but which are not lysed, show betalactam toler- ance (bacteriostatic, but not bactericidal ef- fects). The biosynthesis of bacterial proteins differs in detail from that observed in eukaryotes, per- mitting a selective inhibition by antibiotics. Although the toxin gene is integrated in a phage genome, its activity is regulated by the gene product DtxR of the gene of the bacterial cell’s genome. DtxR combines with Fe2+ to become an active re- pressor that switches off the transcription of the toxin gene. Thick coating (mem- brane) on highly swollen tonsils (so-called diphtherial pseudomembrane), caus- ing respiratory stridor.