Penicillin resistance

Note that values are approximated from references because specific strains are not specified. Penicillin resistant. 

Promoting Optimal Response to Therapy The results of a culture and sensitivity test take several days because time must be allowed for the bacteria to grow on the culture media However, infections are treated as soon as possible In a few instances, the primary health care provider may determine that a penicillin is the treatment of choice until the results of the culture and sensitivity tests are known. In many instances, the primary health care provider selects a broad-spectrum antibiotic (ie, an antibiotic that is effective against many types or strains of bacteria) for initial treatment because of the many penicillin-resistant strains of microorganisms. 

The tetracyclines are important antibiotics often effective against organisms showing penicillin resistance. In 1980, a synthesis of some sulphur containing tetracyclines ° required thiol (14) as an intermediate. The SH group could be introduced by nucleophilic displacement of a diazonium salt (guideline 4) so amine (IS) is an essential intermediate. 

Kanamycin (a complex of three antibiotics. A, B and C) is active in low concentrations against various Gram-positive (including penicillin-resistant staphylococci) and Gram-negative bacteria. It is a recognized second-line dmg in the treatment of tuberculosis. 

A second mechanism of resistance involves alterations in PBPs which affect binding of /3-lactams. These changes have been found to occur by multiple substitutions through recombination rather than point mutations. Acquired penicillin resistance in Strep, pneumoniae is because of such gene mosaics which code for an altered yet functional PBP with reduced affinity for penicillin. Sections of the susceptible PBP gene have been replaced by other DNA sequences, presumably via transformation. 

Traditionally, high-dose penicillin G was the treatment standard for meningococcal disease. However, increasing penicillin resistance requires that third-generation cephalosporins now be used for empirical treatment until in vitro susceptibilities are known.23 Patients with a history of type I penicillin allergy or cephalosporin allergy may be treated with vancomycin. Treatment should be continued for 7 days, after which no further treatment is necessary. 

Treatment of AOM depends on patient age, illness severity, and the certainty of diagnosis. Children younger than 2 years of age have a higher incidence of penicillin-resistant pneumococcal infections and have higher clinical and bacteri-ologic failure rates and complications when not treated initially with antibiotics as compared with older children.5,15 Patients with severe illness, defined by degree of fever and... 

Antibiotic resistance plays a smaller role in pharyngitis therapy compared with other URIs. O Penicillin resistance has not yet been documented in group A streptococci, but resistance and clinical failures occur more frequently with tetracyclines, trimethoprim-sulfamethoxazole, and to a lesser degree macrolides. 

Freeman, R. Gould, F. K. Sisson, P. R. Lightfoot, N. F. Strain differentiation of capsule type 23 penicillin-resistant Streptcoccus pneumoniae from nosocomial infections by pyrolysis mass spectrometry. Lett. Appl. Microbiol. 1991, 13, 28-31. 

Fig. 5.12. A series of resistance genes built on to a bacterial plasmid, ero is erythromycin- and pen a penicillin-resistant gene.

High-dose penicillin (12 million units/day for adults) or ceftiiaxonec or cefotaximec Levofloxaan,1 moxifloxacin,1 gemifloxacin,1 telithromyan, or vancomycin Penicillin-resistant (MIC >1.0 mcg/mL)... 

Vancomycin use should be based on local incidence of penicillin-resistant S. pneumoniae and until cefotaxime or ceftriaxone minimum inhibitory concentration results are available. 

Streptococcus pneumoniae Penicillin susceptible Penicillin intermediate Penicillin resistant Group B Streptococcus Staphylococcus aureus Methicillin susceptible Methicillin resistant Staphylococcus epidermidis Listeria monocytogenes... 

Penicillin resistant Cefotaxime or ceftriaxone (A-lll) Chloramphenicol (A-lll), meropenem (A-lll), fluoroquinolone (A-lll) ... 

Aqueous crystalline penicillin G sodium or 24 million units/24 hours IV either continuously or in four to six equally divided doses 4 IB Patients with endocarditis caused by penicillin-resistant (MIC greater than 0.5 mcg/mL) strains should be Seated with regimen recommended for enterococ-... 

Selection of antibiotics should consider that up to 30% to 40% of H. influenzae and 95% of M. pneumoniae are /1-lactamase producers, and up to 30% of S. pneumoniae are at least moderately penicillin resistant. 

Higher dose amoxicillin, amoxicillin-davulanate (eg., 90 mg/kg/day) is used for penicillin-resistant Streptococcus pneumoniae fluoroquinolones are avoided in pediatric patients because of the potential for cartilage damage however, their use in pediatrics is emerging. Doses shown are extrapolated from adults and will require further study. 

S. pneumoniae isolates are often intermediate resistant to penicillin (8% to 34%) and some are highly penicillin resistant (12% to 21%). Penicillin-resistant isolates are often resistant to multiple antibiotics. fl- Lactam resistance occurs in about 23% to 35% of H influenzae and in up to 100% of M. catarrhalis. 

Treatment failure or prior antibiotic therapy in past 4-6 weeks High suspicion of penicillin-resistant Streptococcus pneumoniae... 

S. aureus accounts for the majority of infections consequently, a penicillin-resistant penicillin or first-generation cephalosporin is recommended. 

The emergence of multidrug-resistant Gram-positive bacteria, such as methicillin-resistant Staphylococcus aureus (MRSA), penicillin-resistant Streptococcus pneumoniae (PRSP), and vancomycin-resistant enterococci... 

Cethromycin Ketolide 2008 2009 2010 RTIs including those caused by macrolide and penicillin-resistant strains... 

Flucloxacillin is an oral beta-lactam penicillin, which is resistant to the enzyme beta-lactamase and is therefore indicated in infections caused by penicillin-resistant organisms. 

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