Susceptibility tests

Hyperacute bacterial conjunctivitis is associated with gonococcal infections in sexually active patients. The causative agents are Neisseria gonorrhoeae or N. meningitidis. Prompt work-up and treatment is required, as corneal perforation occurs in 10% of cases within 48 hours.12 An ophthalmologist should complete a conjunctival scraping and susceptibility testing.10... 

Effectiveness of TB therapy is determined by AFB smears and cultures. Sputum samples should be sent for AFB staining and microscopic examination (smears) every 1 to 2 weeks until two consecutive smears are negative. This provides early evidence of a response to treatment.28 Once on maintenance therapy, sputum cultures can be performed monthly until two consecutive cultures are negative, which generally occurs over 2 to 3 months. If sputum cultures continue to be positive after 2 months, drug susceptibility testing should be repeated, and serum concentrations of the drugs should be checked. 

Heifets LB. Drug susceptibility tests in the management of chemotherapy of tuberculosis. In Heifets LB, ed. Drug Susceptibility in the Chemotherapy of Mycobacterial Infections. Boca Raton, FL CRC Press 1991 89-122. 

Erythromycin is considered the optimal drug for treatment of Campylobacter infections. The rate of resistance of Campylobacter to erythromycin remains low. Other advantages of this drug include ease of administration, low cost, lack of major toxicity, and narrow spectrum of activity.14 The recommended dosage for adults is 250 mg orally four times daily or 500 mg orally twice daily for 5 to 7 days. For very ill patients, treatment with gentamicin, imipenem, cefotaxime, or chloramphenicol is indicated, but susceptibility tests should be performed. 

Dougherty SH. Antimicrobial culture and susceptibility testing has little value for routine management of secondary bacterial peritonitis. Clin Infect Dis 1997 25(suppl 2) S258-261. 

A variety of commercial kits and automated systems are available to test the abilities of bacteria to assimilate, ferment, decarboxylate, or cleave selected organic compounds.46 Their reliability for species identification is usually greater with cultures from clinical samples, where a limited number of bacteria are commonly encountered, and less with environmental soil and water samples, where a great many uncommon or previously unidentified species not in the database are likely to be present.29,45 Additional tests beyond those found in the commercial kits may be necessary for example, the hydrolysis of various nitriles and amides is useful for identifying Rhodococcus spp.47 Some commercial kits for clinical use feature antimicrobial susceptibility testing.21... 

Fahr, A. M. Eigner, U. Armbrust, M. Caganic, A. Dettori, G. Chezzi, C. Bertoncini, L. Benecchi, M. Menozzi, M. G. Two-center collaborative evaluation of the performance of the BD Phoenix automated microbiology system for identification and antimicrobial susceptibility testing of Enterococcus spp. and Staphylococcus spp. J. Clin. Microbiol. 2003, 41,1135-1142. 

Another important advance has been the application of PyMS with ANNs to discriminate between methicillin-resistant and methicillin-sensitive Staphylococcus aureusIn this study DFA and HCA showed that the major source of variation between the pyrolysis mass spectra of 15 methicillin-resistant (MRSA) and 22 methicillin-sensitive Staphylococcus aureus (MSSA) strains resulted from the phage group of the bacteria, rather than from their resistance or sensitivity to methicillin. By contrast, ANNs could recognize those aspects of the pyrolysis mass spectra that differentiated MRSA and MSSA strains. These results gave the first demonstration that the combination of PyMS with ANNs could provide a rapid and accurate antibiotic-susceptibility testing technique. 

Hoeprich and Huston [117] assessed the stability of miconazole and three other antifungal agents under conditions encountered in bioassay and susceptibility testing in vitro. Although the amphotericins were labile as compared with other drugs, tests should be reliable with all four drugs in view of the rapid action of the polyenes and the relatively slow action of miconazole and 5-fluorocytosines. 

Since remarkable symptomatic improvement can be achieved in most patients, antibiotic therapy is obviously the cornerstone of the treatment of SIBO [136], Ideally, the choice of an antimicrobial agent should be based on in vitro susceptibility testing of the bacteria in the small bowel of the individual patient. However, because it is impractical to obtain this information in most cases, the choice of the antibiotic is largely empiric and based on results of published series involving small intestinal cultures [137], Whereas most patients with SIBO have aero-... 

Joyce M, Woods CW Antibacterial susceptibility testing in the clinical laboratory. Infect Dis ClinNorth Am 2004 18 401 134. 

A variety of factors may be responsible for apparent lack of response to therapy. It is possible that the disease is not infectious or nonbacterial in origin, or there is an undetected pathogen. Other factors include those directly related to drug selection, the host, or the pathogen. Laboratory error in identification and/or susceptibility testing errors are rare. 

Empiric antimicrobial therapy should be instituted as soon as possible to eradicate the causative organism (Table 36-2). Antimicrobial therapy should last at least 48 to 72 hours or until the diagnosis of bacterial meningitis can be ruled out. Continued therapy should be based on the assessment of clinical improvement, cultures, and susceptibility testing results. Once a pathogen is identified, antibiotic therapy should be tailored to the specific pathogen. 

Appropriate samples should be sent for culture and susceptibility testing prior to initiating therapy for all patients with active TB. This data should guide the initial drug selection for the new patient. If susceptibility data are not available, the drug resistance pattern in the area where the patient likely acquired TB should be used. 

Study participation, treatment development based on, 8 Study populations, describing, 149 Subscriber agreements, 122 Succinylcholine, 60, 165, 168 Survey Questionnaire, General Population, 337-348 Susceptibility alleles, 52 Susceptibility genes, 44, 86 Susceptibility testing, 181, 306-307 Suter, Sonia, 17 Suxamethonium, 89, 139-140 Syphilis study, 68... 

National Committee for Clinical Laboratory Standards, 1996, Method for Broth Dilution Antifungal Susceptibility Testing Yeast Approved Standard, M27-A, 15, 10, NCCLS, VA Medical Center, Tucson, AZ. 

National Committee for Clinical Laboratory Standards, 2002, Methods for Dilution Antimierobial Susceptibility Tests Bacteria that Grow Aerobieally, 3rd edition. Approved Standard. NCCLS document M100-S12, NCCLS, Wayne, PA. 

EUCAST European Committee on Antimicrobial Susceptibility Testing... 

European Committee on Antimicrobial Susceptibility Testing (EUCAST) (2011) Available from http //www.eucast.org/30 Aug 2011... 

Clinical CLSI (2007) Performance standards for antimicrobial susceptibility testing MIOO-S17. Wayne, PA, 27... 

Andrews JM (2009) BSAC standardized disc susceptibility testing method (version 8). J Antimicrob Chemother 64(3) 454 89... 

Artemisinin-based regimens are often regarded as safe and effective drugs in the recent years however, clinically relevant artemisinin resistance has been reported both from laboratory and field studies. Some of these studies have shown that P. falciparum has reduced in vivo susceptibility to artesunate in western Cambodia as compared with northwestern Thailand. This resistance was characterized by a slow parasite clearance in vivo, without corresponding reductions on conventional in vitro susceptibility testing.Although this resistance to artemisinin is still very mild and limited, its emergence would be disastrous because of the lack of alternative treatments. 

The analyst (farmer, veterinarian, laboratory scientist, or any other user) saturates a cotton tipped swab with sample tissue fluids, serum, urine, or feed extract. He then firmly places the saturated cotton swab on the surface of the appropriate growth medium previously surface streaked with the working dilution of the appropriate susceptible test organism. The test is then incubated at the proper temperature overnight and observed the next day for antimicrobial activity. If there is a zone of inhibition (no growth of the test organism) around the sample swab, the test is positive no inhibition indicates that antimicrobials are absent or below detectable levels in the sample tested. 

Urinary tract infections Nalidixic acid is indicated for the treatment of urinary tract infections (UTIs) caused by susceptible gram-negative microorganisms, including the majority of Escherichia coli, Enterobacter species, Klebsiella species, and Proteus species. Perform disc susceptibility testing with the 30 meg disc prior to administration of the drug and during treatment if clinical response warrants. 

Multidrug resistance The most recent cultures should undergo susceptibility testing to all antituberculosis drugs if cultures remain positive after 3 to 4 months of treatment. 

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