Antibiotic susceptibility

The success of dibekacin prompted worldwide attention to the removal of selected OH groups in aminoglycoside antibiotics susceptible to modification by resistant bacteria, and the chemical deoxygenation procedure of D. H. R. Barton was found particularly useful. 

Infective endocarditis caused by these streptococci typically has a subacute clinical course. The current cure rate is often over 90% unless complications occur, which is the case in more than 30% of patients.17 The majority of viridans streptococci remain very susceptible to penicillin, with most strains having a minimum inhibitory concentration (MIC) of less than 0.125 mcg/mL.15,18 Organisms with decreased susceptibilities are increasing. Therefore, antibiotic susceptibilities need to be assessed in order to determine the most appropriate treatment regimen. 

For enterococci, it is imperative to determine species and antibiotic susceptibilities. If the organism is susceptible to penicillin and vancomycin, treatment may consist of high-dose penicillin G, ampicillin, or vancomycin plus gentamicin (see Table 71-6). Treatment length is usually 4 to 6 weeks, with the aminoglycoside used over the entire course. As resistance develops to penicillin, ampicillin and vancomycin remain treatment options. Once the isolate becomes resistant to ampicillin, vancomycin is considered the treatment of choice. 

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. 

Smaill F Antibiotic susceptibility and resistance testing An overview. Can J Gastroenterol 2000 14 871-875. 

In a recent study, the bacterial populations contaminating the upper gut in SIBO patients and their antibiotic susceptibility were determined. Amoxicillin-clavulanic acid and cefoxitin were effective against >90% of anaerobic strains, while aminopenicillins, cephalosporins and cotrimoxazole were effective against the microaerophilic population. Erythromycin, clindamycin and rifampicin were ineffective. Data on metronidazole and fluoroquinolones are not available [32]. 

Update on topical antibiotic therapy Changing antibiotic susceptibility patterns and clinical implications. Proceedings from a clinical roundtable. November 9,2002, Scottsdale, Arizona, USA. Cutis 2003 71(3 suppl) 2-24. 

Aggressive, early antimicrobial therapy is critical in the management of septic patients. The regimen selected should be based on the suspected site of infection, likely pathogens, and the local antibiotic susceptibility patterns, whether the organism was acquired from the community or a hospital, and the patient s immune status. 

Riordan JT, Dupre JM, Cantore-Matyi SA et al (2011) Alterations in the transcriptome and antibiotic susceptibility of Staphylococcus aureus grown in the presence of diclofenac. Ann Clin Microbiol Antimicrob 10(1) 30... 

Okoh AI, Igbinosa EO (2010) Antibiotic susceptibility profiles of some Vibrio strains isolated from waste water final effluents in a rural community of the Eastern Cape Province of South Africa. BMC Microbiol 10 143... 

On the basis of antibiotic-susceptibility tests of the isolate cultured from the inital sputum (or blood), therapy should be streamlined, preferably within 48 hours. In an uncomplicated course a switch to oral therapy should be made after a few days. If defervescence takes longer than a few days an chest... 

Quinolone antibiotics Susceptible to inhibition of gastrointestinal absorption. Some Caffeine [P] Ciprofloxacin, enoxacin, pipedemic acid, and to a lesser extent,... 

Walsh, S.E. et al., Development of bacterial resistance to several biocides and effects on antibiotic susceptibility. J. Hosp. Infect. 55, 98-107, 2003. 

The component(s) of the mycobacterial cell wall responsible for conferring intrinsic resistance to antibiotics are not yet known with any certainty. However, it has been shown [91-93] that inhibitors of arabinogalactan synthesis increase mycobacterial sensitivity to antibiotics. When M. avium is treated with inhibitors of mycolic acid biosynthesis there are significant alterations in outer cell wall layers and the cells show an increased antibiotic susceptibility [93], Thus, arabinogalactan and mycolic acids are components of the wall associated with intrinsic resistance of mycobacteria to chemotherapeutic drugs and alteration of these structural building blocks leads to increased intracellular penetration of antibiotics [88,94,95],... 

The American Academy of Pediatrics recommends that doxycycline not be used in children less than 9 years of age because of retarded skeletal growth in infants and discolored teeth in infants and toddlers (Inglesby et al., 2002). Because of the serious nature of anthrax infection, however, Inglesby and colleagues (2002) recommend that doxycycline, instead of ciprofloxacin, be used in children if antibiotic susceptibility testing, exhaustion of drug supplies, or adverse reactions preclude the use of ciprofloxacin. 

Pavia M, Nobile CG, Salpietro L, Angelillo IF. Vancomycin resistance and antibiotic susceptibility of enterococci in raw meat. J Food Prot 2000 63(7) 912-15. 

However, several disadvantages can be reported. This PCR method requires two different PCR systems mollil + molli2a to detect all the Mycoplasma and Spiroplasma spp. and mollil + molli2b to detect Acholeplasma spp. The set of primers mollil + molli2a amplifies two phylogeneticaUy closely related species -Clostridium ramosum and C. inocuum - but these species are rarely found as cell culture contaminants. Moreover, this method does not allow bacterial identification of the detected species or antibiotic susceptibility testing. 

Verbist L 1993 Relevance of antibiotic susceptibility testing for clinical practice. European Journal of Clinical Microbiology and Infectious Diseases 12(suppl 1) 2-5 Vogelman B, Gudmundsson S, Leggett J et al 1988... 

The oxazolidinones are a new class of synthetic antimicrobial agents. Produced in 1987, they were found to be active in vitro against antibiotic-susceptible and -resistant cocci and did not demonstrate cross-resistance with any other antibiotics. 

Studies suggest that SOOmg of tetracycline po q 6h could be substituted for doxycycUne. In addition, 400 mg of gatifloxicin or monifloxacin, po daily could be substituted Tf antibiotic susceptibility testing, lack of resources or adverse reactions preclude use of ciprofloxacin... 

TABLE 16.1. Validation Results for the New Qualitative Antibiotic Susceptibility Test... 

Saiman L, Mehar F, Niu WW. Antibiotic susceptibility of multiply resistant Pseudomonas aeruginosa isolated from patients with cystic fibrosis, including candidates for transplantation. Clin Infect Dis 23 532-537, 1996. 

Some infectious diseases pharmacists may collaborate with infection control practitioners to reduce nosocomial infections and control antimicrobial resistance. Others may work closely with clinical microbiologists to design institution-specific susceptibility testing and reporting methods, and to generate periodic antibiotic susceptibility reports. 

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