By W. Varek. Massachusetts College of Art. 2019.
Undoubtedly pericar- needles may be so large as to risk exogenous wicking of diocentesis is best and most safely performed under bacteria into sterile seromas or hematomas that are ultrasound guidance generic nootropil 800mg visa. Therefore the 16-gauge needle seems the best for Following thoracocentesis for diagnostic purposes purchase nootropil 800 mg fast delivery, the initial aspirate in cattle discount nootropil 800 mg with visa. Thoracic trochars or Once needle conrmation has been obtained buy 800 mg nootropil visa, a drains may be anchored in place should continuous or scalpel is used to drain the abscess, and a quick and intermittent drainage be anticipated. A Heimlich s valve rapid procedure is performed only with simple re- should be attached to the exposed external end of the straint if judgment dictates or with mild sedation (15 drain to prevent pneumothorax when continuous drain- to 30 mg of xylazine) in most cattle. Large necrotic clumps of tissue and inam- often increases to cause occlusion or necessitate replace- matory debris should be removed manually from the ment within several days. Each day the incision should be cleansed, and a gloved hand should be used to open the incision. Abscesses eventually soften and drain spontane- Although not considered a routine procedure, liver bi- ously in most cases, but this may require weeks or even opsy may be necessary to conrm diffuse liver disease months. In addition, the lesions cause patient discom- or focal liver lesions identied with the aid of ultra- fort or pain, often interfere with locomotion or normal sound. Once the best site for potential The procedure can usually be performed blindly, but ventral drainage of the suspect abscess is chosen, the without question the use of ultrasound to identify the skin at this site is clipped and surgically prepped. More commonly, however, when the needle is in- troduced, nothing ows from the hub. This dilemma is Dehorning of dairy cattle has long been accepted as a caused by the thick pus typical of that caused by Arcano- routine management necessity in most areas of the bacterium pyogenes, which lls most abscesses. Although veterinarians and owners agree aspirated by attachment of a syringe or by withdrawal of that this task should be performed at as early an age as the needle and observing typically thick yellow-white possible, it is inevitable that labor or time constraints pus clogging the needle and hub. Although use of a develop on some farms with resultant dehorning re- wider bore needle would encourage ow of pus, these maining necessary for cattle 6 to 24 months of age. Laypeople who dehorn livestock almost never attend to details such as local anesthesia, cleanliness or Electric or Heat Dehorning antisepsis, and hemostasis. In addition, complications such as sinusitis and tetanus are much more common This technique is the simplest form of dehorning be- when cattle are dehorned by laypeople. Dehorning tech- cause it can be done as soon as a horn bud can be pal- niques will be discussed from their simplest to most pated in baby calves, requires no hemostasis, can be complex. The age for calves is usually 2 to 8 weeks; they are Anesthesia and Restraint for Dehorning dehorned only if the emerging horn buds are distinctly Local anesthesia by cornual nerve blockade is per- palpable. Local anesthesia inltration of the cornual formed before any dehorning technique. This mini- nerve below the temporal line is provided by 5 ml of 2% mizes operative pain to the patient and also allows the lidocaine on each side. If a long hair coat is present, hair veterinarian to institute postoperative hemostasis with- may be clipped over the horn buds. The heated dehorners that have been preheated before the cornual nerve is a branch of the zygomatic temporal onset of dehorning then are applied such that they nerve and runs from the caudal orbit to the horn surround the horn bud completely, thereby causing a slightly below the temporal line. The nerve lies deeper thermal burn to skin circumferential to the horn and near the orbit and more supercial along the caudal peripheral to the germinal epithelium. Depending on the size of rotated slightly under gentle pressure to ensure unifor- the animal being dehorned, 3 to 10 ml of 2% lidocaine mity of heat distribution. A copper brown ring in the is used to block the cornual nerve with an 18-gauge, burned tissue usually indicates sufcient cautery to pre- 3. Dos- of various factors: poor management that allows calves age depends on the size of the animal, degree of seda- to get too large for effective electric dehorning; aesthet- tion desired, and facilities. Baby calves simply can be hand held or hal- cattle believe that gouge dehorning performed at 4 to tered. Larger calves (older than 4 months) should be 12 months of age yields a more cosmetic head for show tightly secured with a halter and stabilized by stanchion purposes. Such head gates allow the calf to be This instrument, as with electric dehorners, is designed caught easily and will prevent excessive struggling. The for dehorning young calves that remain in the horn bud calf may be restrained by a halter or nose lead, which stage. A plied, twisted while pushed through the skin surround- nose lead is preferable to halters in large calves and ing the horn bud, then rotated to ick off the horn bud adults because it provides better restraint and does and surrounding skin. Hemostasis is attained as neces- not interfere with effective hemostasis as a tight halter sary, and an antiseptic dressing is applied. The method does, which may either accentuate or mask bleeding is quick and effective. Adequate anesthesia and restraint for dehorning cannot be Gouge or Barnes Dehorners overemphasized because without it, the procedure will be prolonged. Gouge or Barnes dehorners are the patient has to be well restrained and positioned in a available in two sizes and can be used in most calves stanchion or head gate. The patient s head is pulled to 3 to 10 months of age, depending on breed and size. The pa- elliptical sharpened metal edge is formed when the tient s head then is pulled to the opposite side and the handles are held together. Positioning of the Keystone causes the sharpened edge to excise skin peripheral to dehorner such that it properly cuts the ventral aspect of the horn and the horn. The gouge must have a large a large horn to allow subcutaneous exposure of the cor- enough circumference to remove skin circumferential nual artery branches requires that the cow s head be to the horn itself effectively, thus preventing regrowth tipped toward the veterinarian and the distal portion of of the germinal epithelium. Anesthesia, cal cutting surface is laid over the long axis of the el- restraint, hemostasis, and topical antiseptic care are per- liptical horn base once the head has been restrained formed as previously described. Hemostasis is Power Dehorners completed by pulling bleeding cornual arteries with artery forceps, followed by topical application of an Mechanical guillotine-type power-driven dehorners are antiseptic spray or solution. They are used when large num- bers of heifers or adults require dehorning or when the veterinarian seeks to reduce the work required in using Keystone Dehorners gouges or Keystone dehorners. The techniques are Keystone dehorners are necessary for heifers or young similar to those described for the Keystone dehorner, bulls with large horn bases and for adult cattle. Large and once again adequate restraint is essential to proper wooden handles operate the guillotine-type blades that technique. Keystone dehorners are these devices because injuries to assistants or the heavy, somewhat cumbersome and dangerous, but effec- veterinarian are potential hazards of using any power tive if used properly. Wire frequently is used to dehorn bulls, even yearling bulls, with wide horn bases and horns that pro- trude perpendicular to the longitudinal plane. Heifers especially have horns that curl upward as they project from the skull, whereas bulls often have horns that pro- ject outward, making it difcult to position dehorners properly to ensure a successful cut. Too often an im- proper cut with gouges or Keystone dehorners leaves a bull with a shelf of bone on the ventral horn base. This not only allows growth of horn ( skurl ) but also pre- cludes adequate hemostasis of the cornual artery be- cause the artery is cut transversely and the cut end re- mains embedded in bone. From top a sawing motion while holding the wire with obstetric to bottom: small Barnes gouge, large Barnes gouge, Key- wire handles. As with Keystone dehorners, the inside stone dehorner, an electric dehorner, and a Roberts or horn (closer to the stanchion) is removed as the head is tube dehorner. Proper removal technique allows hemostasis because the cornual artery is exposed in a subcutaneous location. Dehorning Saws Box-type saws have been used to dehorn cattle, and the technique is similar to that used with obstetric wire. The artery is represented by dotted lines where it Cosmetic Dehorning remains buried, and the solid dark lines represent the cut ends that become apparent after dehorning. These Cosmetic dehorning is not as popular in dairy cows as cut ends then are pulled with artery forceps to establish in beef cows. Improper cuts that fail to remove all of wound healing resulting from primary closure of the the bone in the ventral aspect of the horn leave the cut wounds. When this occurs, the patient, local anesthesia, clipping of the entire poll re- ends of the arteries cannot be grasped or ligated. Skin around cuts expose both branches subcutaneously and allow the the horn and peripheral to the germinal epithelium is arteries to be grasped with artery forceps and pulled. Sterile obstetric The ventral branch should be grasped, gently stretched, wire is placed under the skin incision, and the horn is and pulled caudally until it breaks.
Introduction Myiasis (derived from the Greek myia = a y) refers to the invasion of human or animal tissues by the larvae (maggots) of ies (Diptera) discount nootropil online mastercard. The larvae feed on tissue (living or dead) order nootropil 800mg mastercard, or in the case of intestinal myiasis discount 800 mg nootropil fast delivery, on ingested food buy generic nootropil online. Facultative myiasis occurs when larvae enter living tissue after residing in nearby, decaying, or vegetable tissue in a wound. Obligatory myiasis refers to true parasitism, in which a portion of the larvae s developmental stage is spent in living tissue. Most commonly, this occurs in animals such as sheep, cattle, and horses but human tissue invasion by the human boty of Central and South America is well documented. These larvae are typically inadvertently ingested with food, or have wandered into these areas of the body. There is no dipterous obligate intestinal parasite Imported Skin Diseases, Second Edition. While typically a benign event, stomach pain, nausea, and vomiting can result from accidental myiasis . Pathogenesis Several families of ies that result in myiasis in humans exist and is dis- cussed in the following text. Calliphoridae (metallic ies) Genus Cochliomyia The New World screwworm Cochliomyia hominivorax (previously known as Cochliomyia americana and Callitroga americana) or human-eater, is an obligate parasite of cattle and other livestock. The species name, human- eater, refers to the once held thought that it resulted in the deaths of hundreds of prisoners on Devil s Island . Adult ies have three distinct dark longitudinal stripes on the dorsal thorax, are green-blue in color and range in size from 8 to 10 mm. Their dorsal bristles are poorly developed and it has a hairless thoracic squama, a membranous lobe on the posterior border of the wing. Not only can they penetrate unbroken skin but they may also infest wounds, scabs, sores, and even healthy mucous membranes. The larvae have distinct spicules that encircle the anterior margins of all body segments, unlike the housey maggot. Genus Chrysomya Chrysomya bezziana, the Old World screwworm, is an obligate parasite in living tissues such as wounds. This is in contrast to larvae from other species that develop in carrion and decomposing matter. It is found in Africa, from Ethiopia in the north to Natal and the Transvaal in the south. Adults are relatively large, ranging in size from 9 to 12 mm, with a yellow to light brown color and two dark gray, poorly dened dor- sal longitudinal thoracic stripes. The abdominal segment has four visible segments, each approximately equal in size. Cordylobia rodhaini (also known as Lund s y), the only other species of Cordylobia known to infest humans, has a more limited distribution in tropical Africa, principally the rainforest areas. In most cases, there is more than one lesion, and very extensive furuncular myiasis due to C. Females may lay up to 100 300 white and banana-shaped eggs on sand or soil in shaded areas, especially if contaminated by urine or feces, and also on laundry hanging out to dry or babies diapers. In the wild, rats are the usual host, but around human habitation dogs and humans are common hosts. Once on a human, the larva uses its powerful oral hooks to attach itself to the host and rapidly penetrates the skin, leaving only its posterior spicules at the top of its abdomen in contact with the air. When development is complete (usually in 14 16 days) it leaves the host and falls to the ground, where they bury themselves and pupate. Other genera Several larvae may act as secondary invaders of wounds in humans and include members of the genera Phormia (black blowies), Lucilia [Phaeni- cia] (greenbottle), and Calliphora (bluebottle). A study of wound myiasis in urban and suburban United States demonstrated that the majority of species identied were blowies, the most common being Lucilia sericata . Homelessness, alcoholism, and peripheral vascular disease were fre- quent cofactors. There has been a recent resurgence of interest in the use of maggots for wound debridement, and the larvae of L. When using maggots for debridement, it is obviously important to choose only maggots that remain in necrotic rather than living tissue and to avoid species that invade viable tissue. Sarcophagidae (esh ies) Genus Sarcophaga Wound infestation by members of this genus has been reported. The species are large, 10 15 mm in length, gray in color and have overlying Myiasis 255 hairs. Occasionally, a chessboard appearance of the abdomen may be seen as dark square patches alternate on a gray background. Sarcophaga cruentata (also known as Sarcophaga haemorrhoidalis) is the most widely dis- tributed and common species. Approximately 40 60 larvae will be deposited on decay- ing food, excreta or carcasses where they serve as primary scavengers. The larvae of Sarcophagidae are distinguished from Calliphoridae in that they have posterior spiracles situated in a deep pit. Female ies deposit approximately 120 170 larvae, not eggs, in wounds or beside body ori- ces. Wohlfahrtia magnica is likely the most important species and is an obligate myiasis-producing y in humans and animals such as camels and sheep. Wohlfahrtia vigil vigil and Wohlfahrtia vigil opaca are North American species whose females deposit larvae on unbroken and soft skin, result- ing in furuncular myiasis. Human furuncular myiasis from these species occurs only in infants, as the larvae are unable to penetrate adult skin. Oestridae The Oestridae contain four subfamilies, three of which are obligate para- sites of domestic animals (Oestrinae, Gasterophilinae, and Hypodermati- nae). The Cuterebra subfamily has several species that can cause myiasis in rodents, monkeys, and livestock. Another member of this subfamily, Dermatobia hominis, causes myiasis in people and animals in Central and South America. Genus Cuterebra (rodent or rabbit boty) Rabbits and rodents are the natural hosts for the larvae of these ies, which are among the most frequent causes of North American-acquired human furuncular myiasis . It can be found in the neotropical areas of the New World, extend- ing from southern Mexico to northern Argentina. It occurs where tem- perature and humidity are relatively high, principally in lowland forests, especially in woodland paths at along forest and scrub areas. The female y sticks approximately 6 30 eggs on to the body of other insects such as day-ying mosquitoes, blood-sucking ies and even ticks, which then serve as vectors to carry her eggs to the host (a process known as phoresy). The process is a wonder of nature, as the female y deftly grabs the insect vector in mid-air and deposits eggs on its abdomen. The larvae then emerge and within 10 minutes are able to burrow into the subcutaneous tissues. The burrow results in a boil-like lesion with an opening, through which the larvae breathes. Larval development lasts approximately 50 60 days, following which the larva emerges, drops to the ground and pupates. Genus Gasterophilus (horse boty) A form of migratory cutaneous myiasis known as creeping eruption is caused by Gasterophilus larvae. The larvae will only be noted in the conjunctival sulcus when the eyelid is everted. Genus Hypoderma (warble ies) The larvae of Hypoderma species are obligate parasites of cattle. After pen- etrating the skin, the larvae produce migratory subcutaneous swellings. Muscidae Fannia canicularis (lesser housey) and Musca domestica (housey) may deposit their eggs in wounds and ulcers, giving rise to facultative wound or urogenital myiasis. Urogenital myiasis results when ovipositing ies lay their eggs near genital orices, resulting in larvae entering the genital canal, causing pain and the even the eventual excretion of larvae within the urine. Clinical features Flies and their larvae result in different clinical manifestations depending on the setting and the location of the body they affect. Facultative wound myiasis is a complication of war wounds in tropical areas, and can be seen in invalids with poor access to health care.
Williamson and Schulz  found that activity restriction mediated the relationship between pain and symptoms of depression purchase nootropil australia, and accounted for differences in pain intensity between non-depressed people and those at risk for developing depression buy cheap nootropil 800mg line. Social support buy nootropil 800mg with visa, relationships with others cheap 800 mg nootropil free shipping, and resources can be dened as the availability of tangible (e. Older adults with chronic health con- ditions often have difculty participating in everyday activities [203, 204 ], thus affecting their quality of life and ability to participate in their communities. Social isolation has an especially important impact on pain and disability in older adults. In turn, per- sistent pain contributes to increased social isolation, as older adults with chronic pain spend less time in previous social roles and experience greater restrictions in social and leisure activities [206, 207]. Variations in the family, community, home, and healthcare environments can play important roles in how older adults adjust to pain. Signicant others may express sympathy and excuse the individual from responsibilities, and encourage passivity, thereby fostering further functional impairment. Nursing homes are often perceived as coercive settings, promoting non-autonomous orientation that restricts activities. When events are objectively coercive, people may perceive a lack of autonomy and hence be at greater risk of depression. What may really be important to emotional well-being is not so much pain itself, but the way in which pain alters older people s lives. These can be grouped into several general classes: (1) educational, (2) pharmacological, (3) activation (physical exercises), (4) psychological (e. Each of these classes of medica- tions may provide some level of pain relief, but often there are signicant limita- tions and some adverse effects associated with each of them, particularly when used in older adults. Medical comorbidities are an important consideration in treating pain in older persons. Older adults often have several medical conditions in addition to the par- ticular pain diagnosis (e. In addition, liver mass, liver blood ow, and the glo- merular ltration rate of kidneys decrease with age. Of particular clinical impor- tance, reduced renal clearance leads to a decline in the excretion of water-soluble drugs . Lowered activities of most of the cytochrome P450 enzymes reduce the drug-elimination clearance rate of the liver, especially in the presence of chronic disease . In a United States study published over a decade ago, 50 % of patients aged 65 or older consumed ve or more prescription drugs and 10 % were using ten or more medications . Polypharmacy can be a confounding risk factor when prescrib- ing pain medications as there are both known and unknown drug-drug interactions that need to be considered. With polypharmacy, dose-limiting adverse effects of pain- relieving medications may limit the potential achievable efcacy. Because of the increased likelihood of drug-drug and drug-disease interactions, as well as the pharmacokinetic and pharmacodynamic challenges associated with polypharmacy in older adults, frequent monitoring is critical when analgesic medications are prescribed. Age-related changes in body composition and organ function can also alter metabolic and pharmacokinetic responses to medications. These changes along with medical and psychiatric comorbidities and concomitant polypharmacy (see also [219, 220]), suggest that conventional pharmacological therapies may not always be appropriate for older adults and should be used with caution [221 224]. Analgesics are often inappropriately prescribed for elderly patients, failing to follow clinical practice guidelines [228, 229]. Opioids are poorly tolerated by elderly patients [228, 230], and antidepressants and anticonvulsants are limited due to their effects on hepatic and renal function that may already be compromised because of the aging process. In sum, although conventional pharmacological treatments for pain can pro- vide some relief for symptoms, they have signicant hazards in older adults that need to be balanced in treatment decisions. Moreover, in general, pharmacologic treatments provide only modest reductions in pain (30 % in fewer than 50 % of treated patients) and little impact on improving func- tion . There have been few studies that specically address the issue of treat- ment effectiveness with older adults. In view of the limited evidentiary base and well-established adverse effects of current analgesic medications, there is an urgent need to develop both safe and effective pharmacological and non-pharma- cological therapies for the rapidly growing older population. Greater emphasis on non-pharmacological approaches, alone or in combination with lower doses of pharmacological agents, may be particularly important for older adults with chronic pain. Exercise is widely recognized as an approach for reducing pain and improving physical function in patients with chronic pain regardless of age [235, 236]. Despite recommendations for exercise, several studies have shown that objectively mea- sured levels of physical activity are signicantly lower in older chronic pain popula- 574 R. Indeed, as noted, activity restriction is a commonly reported strategy older adults use to reduce pain . An important target for physical activation in older adults is improved balance [237 239]. Unpublished exit interview data identified pain as a lead- ing cause of non-adherence. Greater adherence may lead to better outcomes but as noted below, adherence with any self-management regimen is a significant concern. It has emerged as a viable exercise intervention, and it is recom- mended for older populations by the American Geriatrics Society [221 ]. It has been shown to be more effective than other exercises for improving mobility and reducing fear of fall- ing in older adults [246, 249 ]. In general, increasing exercise is a key challenge to address in the geriatric population as relatively few older adults use exercise and other behavioral strate- gies to cope with pain [177, 250]. Instead, passive strategies and avoidant behav- iors are more common and associated with increased disability . The results are comparable to those reported for exercise in community-dwelling older adults [249, 258]. Of particular interest is the use of neuroimaging technologies to identify changes in brain function that accompany alterations in pain perception and responses fol- lowing pain treatments. Jensen  has hypothesized that different psychological pain treatments and changes in the psychological factors targeted by these treat- ments (e. In addition, neuroimaging studies suggest that non-pharmacological approaches may produce positive structural brain changes in areas that often decline with aging (i. These may be of particular concern for older adults who have cognitive and sensory limitations. Treatments that were originally developed for younger individuals need to have appropriate adaptations and adjustments in content and format when prescribed for the elderly to accommodate any age-related limitations. Successful treatment of older people with chronic pain will require that problems associated with treatment adherence be addressed regardless of the intervention pharmacological or non-pharmacological. Epidemiological and clinical studies demonstrate that pain prevalence and impact change with age, although patterns vary for different types of pain; some pain con- ditions increase while others decrease in prevalence with age. Preclinical models reveal conicting ndings regarding age-related changes in nociceptive sensitivity, likely due to methodological variations. Additional research is needed to more clearly dene the biopsychosocial factors that contribute to age-related changes in pain processing. Likewise, multiple psychosocial factors inuence pain experiences among older adults, including beliefs and perceptions, negative mood (e. However, limited information exists regarding the extent to which each of these factors individually contributes to age-related inuences on pain, let alone their interactions. Pharmacologic therapies offer limited clin- ical efcacy and produce increased adverse effects in older adults, and non- pharmacologic treatments, while effective, are often underprescribed in elderly patients. Based on the current state of the evidence, we recommend the following lines of investigation to move the eld of pain and aging forward. Specically, additional cross-sectional and longitudinal studies comparing vari- 578 R. Addressing these issues and adopting these methodological enhancements should help reduce inconsistencies in the literature, thereby substantially improving our understanding of age-related inuences on pain. Ahacic K, Kareholt I (2010) Prevalence of musculoskeletal pain in the general Swedish popu- lation from 1968 to 2002: age, period, and cohort patterns. Gagliese L, Melzack R (2003) Age-related differences in the qualities but not the intensity of chronic pain. Support Care Cancer (Ofcial Journal of the Multinational Association of Supportive Care in Cancer) 19(3):417 423. Pollack M, Leeuwenburgh C (2000) Molecular mechanisms of oxidative stress in aging: free radicals, aging, antioxidents and disease. J Neurosci (The Ofcial Journal of the Society for Neuroscience) 29(47):15017 15027.
Inhibition of this transpeptidase discussion of specic regimens is included in the later prevents the cross-linking of the cell wall peptido- chapters that cover infections of specic anatomic sites cheap 800mg nootropil amex. About -Lactam Antibiotics The activity of all -lactam antibiotics requires active bacterial growth and active cell wall synthesis buy cheap nootropil 800mg online. Penicillins order 800mg nootropil amex, cephalosporins buy nootropil 800mg line, and carbapenems killed, but those in an active log phase of growth are are all b-lactam antibiotics: quickly lysed. Hypersensitivity reactions are the most common side effects associated with the -lactam antibiotics. Penicillins are the agents that most commonly cause allergic reactions, at rates ranging from 0. Ceftriaxone is excreted in high con- allergies also prove to be allergic to cephalosporins and centrations in the bile and can crystallize, causing biliary carbapenems. Cefepime has been associated with antigens increase the probability of a host immune encephalopathy and myoclonus in elderly individuals. In combi- IgE-mediated hypersensitivity reaction that can result nation with aminoglycosides, cephalosporins demon- in anaphylaxis and urticaria. Because of the potential dan- Penicillins ger, patients with a history of an immediate hypersen- sitivity reaction to penicillin should never be given Tables 1. High levels of immunoglobulin G anti- Penicillins vary in their spectrum of activity. Natural penicillin antibodies can cause serum sickness, a syn- penicillins have a narrow spectrum. As a consequence, the penicillins must be dosed frequently, and dosing must be adjusted in patients with renal dysfunction. Allergic reactions are most common toxicity, and this agent can be used to sustain higher serum levels. Nephrotoxicity sometimes occurs when now frequent ( 30%)]; infections caused by cephalosporins are given in combination with mouth flora; Clostridium perfringens or spiro- aminoglycosides. Depending on the specic drug, penicillins can be given treatment of infections caused by mouth ora. Some penicillins have G is also primarily recommended for Clostridium perfrin- been formulated to withstand the acidity of the stomach gens, C. Penicillins are well distributed in multocida, and spirochetes including syphilis and Lep- the body and are able to penetrate most inamed body tospira. However, in many areas of the ence of inammation, therapeutic levels are generally United States, more than 30% of strains are moderately achievable in the cerebrospinal uid. In these Spectrum of Activity and Treatment Recommenda- cases, ceftriaxone, cefotaxime, or high-dose penicillin tions Pencillin G (Table 1. Capnocytophaga canimorsus, clavulanate adds Citrobacter freundii Fusobacterium nucleatum, susceptibility to: Serratia spp. Infections with high- effective against Shigella exneri and sensitive strains of level penicillin-resistant S. Amoxicillin can be used to 2 g/mL) require treatment with vancomycin or another treat otitis media and air sinus infections. However, the superiority of Amoxicillin has excellent oral absorption: 75% as com- amoxicillin clavulanate over amoxicillin for middle ear pared with 40% for ampicillin. As observed with the natural penicillins, the half-life cillins have the same half-life as penicillin (30 minutes) is short (1 hour) and these drugs are primarily excreted and require dosing at 4-hour intervals or constant unmodied in the urine. Unlike the natural Spectrum of Activity and Treatment Recommenda- penicillins, these agents are cleared hepatically, and tions The spectrum of activity in the aminopenicillins doses of nafcillin and oxacillin usually do not need to is slightly broader than in the natural penicillins be adjusted for renal dysfunction. Intravenous ampicillin is recommended for hepatic excretion of nafcillin means that the dose treatment of Listeri monocytogenes, sensitive enterococci, needs to be adjusted in patients with significant Proteus mirabilis, and non -lactamase-producing hepatic dysfunction. These oral agents are used primarily for mild soft-tissue infections or to complete therapy of a resolv- About the Aminopenicillins ing cellulitis. Short half-life (1 hour), and clearance similar to Pharmacokinetics The half-lives of ticarcillin and natural penicillins. Parenteral ampicillin indicated for Listeria been discontinued in favor of ticarcillin clavulanate and monocytogenes, sensitive enterococci, Proteus piperacillin tazobactam. Whenever possi- of piperacillin tazobactam should be increased from ble, vancomycin should be avoided. In combination with an the initial drug of choice for otitis media and aminoglycoside, piperacillin tazobactam often demon- bacterial sinusitis. Amoxicillin clavulanate has improved cover- administration of the piperacillin tazobactam needs to age of Staphylococcus, H. Increased efcacy Spectrum of Activity and Treatment Recommenda- compared with amoxicillin is not proven in tions Ticarcillin and piperacillin are able to resist otitis media. However, covers amoxicillin- -lactamases produced by Pseudomonas, Enterobacter, resistant H. These antibiotics can be used for empiric coverage of moderate to severe intra-abdominal infections. They efficiently, and so dose adjustment is usually not have been combined with a -lactamase inhibitor (clavu- required in liver disease. Spectrum of Activity and Treatment Recommenda- These agents are reasonable alternatives to nafcillin tions The synthetic modication of penicillin to ren- or oxacillin when gram-negative coverage is also der it resistant to the -lactamases produced by S. Because oral preparations result in consid- About Carboxypenicillins and Ureidopenicillins erably lower serum concentration levels, cloxacillin or 1. Ticarcillin clavulanate and piperacillin tazobac- tam have excellent broad-spectrum coverage, including methicillin-sensitive Staphylococcus 1. Primarily indicated for methicillin-sensitive hospital aspiration pneumonia, and mixed soft- Staphylococcus aureus and cellulitis. They have been used for skin and bone infec- tions thought to be caused by a combination of gram- Pharmacokinetics Cefazolin, the preferred parenteral negative and gram-positive organisms. The rst-generation cephalosporins Cephalosporins penetrate most body cavities, but they fail to cross the Tables 1. First- generation cephalosporins are predominantly effective against gram-positive cocci. The third-genera- About First-Generation Cephalosporins tion cephalosporins demonstrate even greater activity against gram-negative bacilli, but only limited activity 1. Useful for treating soft-tissue infections and for urally leads to the assumption that newer, later- surgical prophylaxis. Can often be used as an generation cephalosporins are better than the older alternative to oxacillin or nafcillin. The half-lives of cephalexin and cephradine are the newer penicillins, second-generation cephalosporins short, requiring frequent administration. Because cefoxitin and cefotetan demonstrate increased Spectrum of Activity and Treatment Recommenda- anaerobic coverage, including many strains of B. They intra-abdominal infections and mixed aerobic anaerobic are active against oral cavity anaerobes, but are soft-tissue infections, including diabetic foot infections. Cefaclor, the other second-generation oral prepara- Because of its inability to cross the blood brain barrier, tion, is inactivated by -lactamases produced by cefazolin should never be used to treat bacterial menin- H. Oral preparations are commonly used to treat less has been recommended for otitis media, other oral severe soft-tissue infections, including impetigo, early antibiotics are generally preferred. The half-lives of these Spectrum of Activity and Treatment Recommenda- agents vary, being as short as 1. They penetrate most increased activity against some gram-negative strains, body sites effectively. About Second-Generation Cephalosporins These agents have excellent cidal activity against S. Improved activity against Haemophilus inuen- of this generation are ineffective for treating Enterococ- zae, Neisseria species, and Moraxella catarrhalis. A large number of iotetrazole ring that decreases prothrombin third-generation cephalosporins are available, all with production. Ceftriaxone is recommended for treat- Pharmacokinetics Clearance of the fourth-generation ment of N. Cefotaxime is cleared renally and cephalosporins is renal, and the half-lives of these agents does not form sludge in the gallbladder. For this reason, are similar to the renally cleared third-generation this agent is preferred over ceftriaxone by some pediatri- cephalosporins (Table 1. The R substitution of the 2 cians, particularly for the treatment of bacterial meningitis fourth-generation cephalosporins contains both a posi- in children where high-dose therapy has been associated tively and negatively charged group that, together, have with symptomatic biliary sludging.