Antimicrobial drugs

Parasitic Infections

What does the infectious disease specialist mean by parasitic infection? Most infectious agents fulfill the definition of a parasite: an organism that grows, feeds, and shelters on or in a different organism and contributes nothing to the host. However, medical science has created the classification “parasite” to include a complex group of nonfungal eukaryotic human pathogens. Unlike fungi, parasites have no cell wall and are often motile. In addition, many parasites require two or more host species to complete their life cycle, and they reproduce both sexually and asexually. The host in which sexual reproduction takes place is called the “definitive host,” and the one in which asexual reproduction occurs is …

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Tissue Protozoa

Leishmaniasis Prevalence, Epidemiology, and Life Cycle Leishmania has caused major epidemics in eastern India, Bangladesh, and East Africa. Urban outbreaks have been reported in the cities of northeastern Brazil. A small number of American military personnel contracted leishmaniasis during the Persian Gulf War in 1991 and in Afghanistan more recently. Indigenous cases have been reported occasionally in the United States, but most U.S. cases result from travel to a tropical country. Leishmaniasis has emerged as an opportunistic infection in patients with HIV or an organ transplant. The Leishmania parasite is transmitted by the female phlebotomine sandfly. Sandflies breed in cracks in the walls of dwellings, in rubbish, and in rodent burrows. …

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Intestinal Helminths

Potential Severity Infections are often asymptomatic. In the immuno-compromised host, Strongyloides can progress to a fatal hyperinfection syndrome. Helminths include the roundworms (nematodes), flukes (trematodes), and tapeworms (cestodes). These parasites are large, ranging in size from 1 cm to 10 m, and they often live in the human gastrointestinal tract without causing symptoms. Only when the infection is very heavy or the worm migrates to an extraintesti-nal site do patients seek medical attention. Transmission to humans results in most cases from contact with human waste. The diagnosis is generally made by examining the stool for eggs, larvae, or adult worms. Intestinal Nematodes (Roundworms) Nematodes can be classified into two groups. Those …

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Tissue And Blood Helminths

Trichinella Potential Severity Usually asymptomatic, but heavy infections can lead to severe myocarditis, pneumonia, and encephalitis that can be fatal. Prevalence, Epidemiology, and Life Cycle Trichinosis is found worldwide, wherever contaminated meat is undercooked. Trichinella is a roundworm whose larvae are released from cyst walls in contaminated meat by acid-pepsin digestion in the stomach. Upon entering the small intestine, larvae invade the intestinal microvilli and develop into adult worms. Females then release larvae that enter the bloodstream and seed skeletal and cardiac muscle. The larvae grow in individual muscle fibers and eventually become surrounded by a cyst wall. Once encysted, the larvae can remain viable for many years. If the cyst-containing …

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Filariasis (Wuchereria Bancrofti And Brugia Malayi)

Potential Severity A chronic debilitating infection that can cause severe disfiguring complications by blocking lymphatic drainage. Prevalence, Epidemiology, and Life Cycle Microfilaria is less common than many parasites, being estimated to infect approximately 120 million people. Several strains of worm can cause this disease. Wuchereria bancrofii is found throughout the tropics, and Brugia malayi is restricted to the southern regions of Asia. A third strain, Brugia timori is found only in Indonesia. Infectious larvae are transmitted by the bite of a mosquito. Larvae pass from the skin into the lymphatic system, where, over several months, they mature near the lymph nodes. Adult worms (40 to 100 mm in length) can survive …

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Antimicrobial Regimen Selection

Introduction A generally accepted systematic approach to the selection and evaluation of an antimicrobial regimen is shown in Table Systematic Approach for Selection of Antimicrobials. An «empiric» antimicrobial regimen is begun before the offending organism is identified, while a «definitive» regimen is instituted when the causative organism is known. Confirming the presence of infection Fever Fever is defined as a controlled elevation of body temperature above the normal range of 36.7 to 37.0В°C. Fever is a manifestation of many disease states other than infection. Many drugs have been identified as causes of fever. Drug-induced fever is defined as persistent fever in the absence of infection or other underlying condition. The fever …

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Antimicrobial therapy: general principles

A wide variety of antimicrobial agents is available to treat established infections caused by bacteria, fungi, viruses, or parasites. This section will cover the general principles of antimicrobial therapy and will also include illustrative clinical problems to emphasize proper decision-making in using antimicrobials. Determinants of Antimicrobial Efficacy Measurement of antimicrobial activity in vitro Susceptibility testing is indicated for any bacterial pathogen warranting chemotherapy. Drugs that irreversibly destroy the ability of an organism to replicate, and perhaps in the process destroy the structural integrity of the organism, are microbicidal. Drugs that reversibly impair replicating ability, with this function being restored when drug concentrations fall below critical inhibitory levels, are microbiostatic. In quantitative …

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Toxicity of Antimicrobial Therapy

Mechanisms of toxicity The mechanisms associated with common adverse reactions to antimicrobials include dose-related toxicity that occurs in a certain fraction of patients when a critical plasma concentration or total dose is exceeded, and toxicity that is unpredictable and mediated through allergic or idiosyncratic mechanisms. For example, certain classes of drugs such as the aminoglycosides are associated with dose-related toxicity. In contrast, the major toxicity of the penicillins and cephalosporins is due to allergic reactions. These differences are explained in part by the relative ability of specific drugs to inhibit enzymatic pathways in the host versus their stimulation of specific immune response. Not included in these lists is mention of the …

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Guide to antimicrobial use in adults

• All IV antibiotics should be reviewed at 48 hours, with a view to switching to oral • All antibiotic courses should be reviewed at 5 days, with a view to stopping URINARY TRACT INFECTION 1. Lower UTI – Trimethoprim, cefalexin or nitrofurantoin. (amoxicillin only if lab report indicates sensitivity). 3 days therapy is usually adequate in women. 2. Acute Pyelonephritis – Cefuroxime IV. RESPIRATORY TRACT INFECTION See below MENINGITIS An initial dose of antibiotic should be given immediately if meningitis / meningcoccaemia is suspected. Cefotaxime 2-3 g qds Length of course: Meningococcal – 5-7 days Haemophilus – 10 days Pneumococcal – 10 -14 days For infection control and management of …

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