Penicillin

About: Penicillin is a research topic. Over the lifetime, 17916 publications have been published within this topic receiving 368480 citations. The topic is also known as: penicillin antibiotic & PCN.

In vitro susceptibility of recent North American group A streptococcal isolates to eleven oral antibiotics

Abstract: Because of the recent resurgence of Group A streptococcal infections and their sequelae and to concerns about Group A streptococcal antimicrobial resistance, 282 isolates from acute pharyngitis and 43 additional isolates from severe, invasive infections were examined for susceptibility to 11 oral antibiotics. M serotypes 1, 2, 3, 4 and 12 accounted for more than one-half of the pharyngeal isolates; M serotypes 1 and 3 accounted for most isolates from severe infections. All 325 isolates were exquisitely susceptible to penicillin (Concentration of antibiotic required to inhibit 90% of isolates, 0.012 micrograms/ml). Only approximately 4% of the tested strains demonstrated an erythromycin minimum inhibitory concentration of 0.5 microgram/ml or greater; the new macrolides, azithromycin and clarithromycin, were similar. The cephalosporins varied somewhat in their ability to inhibit Group A streptococci, but all were effective in vitro. No major differences in minimum inhibitory concentrate were observed between strains associated with severe infections and those from uncomplicated upper respiratory tract infections. On the basis of the 325 isolates examined, we conclude that antimicrobial resistance has not been a factor in the recent resurgence of Group A infections.

Development and Validation of a Penicillin Allergy Clinical Decision Rule.

Abstract: Importance Penicillin allergy is a significant public health issue for patients, antimicrobial stewardship programs, and health services. Validated clinical decision rules are urgently needed to identify low-risk penicillin allergies that potentially do not require penicillin skin testing by a specialist. Objective To develop and validate a penicillin allergy clinical decision rule that enables point-of-care risk assessment of patient-reported penicillin allergies. Design, Setting, and Participants In this diagnostic study, a multicenter prospective antibiotic allergy–tested cohort of 622 patients from 2 tertiary care sites in Melbourne, Australia (Austin Health and Peter MacCallum Cancer Centre) was used for derivation and internal validation of a penicillin allergy decision rule. Backward stepwise logistic regression was used to derive the model, including clinical variables predictive of a positive penicillin allergy test result. Internal validation of the final model used bootstrapped samples and the model scoring derived from the coefficients. External validation was performed in retrospective penicillin allergy–tested cohorts consisting of 945 patients from Sydney and Perth, Australia, and Nashville, Tennessee. Patients who reported a penicillin allergy underwent penicillin allergy testing using skin prick, intradermal, or patch testing and/or oral challenge (direct or after skin testing). Data were collected from June 26, 2008, to June 3, 2019, and analyzed from January 9 to 12, 2019. Main Outcomes and Measures The primary outcome for the model was any positive result of penicillin allergy testing performed during outpatient or inpatient assessment. Results From an internal derivation and validation cohort of 622 patients (367 female [59.0%]; median age, 60 [interquartile range{IQR}, 48-71] years) and an external validation cohort of 945 patients (662 female [70.1%]; median age, 55 [IQR, 38-68] years), the 4 features associated with a positive penicillin allergy test result on multivariable analysis were summarized in the mnemonic PEN-FAST:penicillin allergy,five or fewer years ago,anaphylaxis/angioedema,severe cutaneous adverse reaction (SCAR), andtreatment required for allergy episode. The major criteria included an allergy event occurring 5 or fewer years ago (2 points) and anaphylaxis/angioedema or SCAR (2 points); the minor criterion (1 point), treatment required for an allergy episode. Internal validation showed minimal mean optimism of 0.003 with internally validated area under the curve of 0.805. A cutoff of less than 3 points for PEN-FAST was chosen to classify a low risk of penicillin allergy, for which only 17 of 460 patients (3.7%) had positive results of allergy testing, with a negative predictive value of 96.3% (95% CI, 94.1%-97.8%). External validation resulted in similar findings. Conclusions and Relevance In this study, PEN-FAST was found to be a simple rule that accurately identified low-risk penicillin allergies that do not require formal allergy testing. The results suggest that a PEN-FAST score of less than 3, associated with a high negative predictive value, could be used by clinicians and antimicrobial stewardship programs to identify low-risk penicillin allergies at the point of care.

The effective concentrations of penicillin in vitro and in vivo for streptococci, pneumococci, and Treponema pallidum

Abstract: In the therapeutic use of penicillin, the question as to whether the minimum effective concentration in vivo is the same, greater, or less than that necessary to kill the same organ'sm in vitro is of obvious importance. Data are here reported with respect to the minimal effective serum concentrations of penicillin in a number of experimental infections in mice and rabbits. As will be shown, these serum levels were usually 2 to 5 times higher than those necessary to kill the same organism in vitro. However, in view of the known concentration differential between the serum and tissue fluids, this suggests that the effective concentration of penicillin at the actual site of infection is in most instances the same as that effective in vitro.

Antibiotic-resistant Staphylococcus epidermidis in patients undergoing cardiac surgery.

Abstract: Staphylococcus epidermidis isolates containing subpopulations resistant to 100 microgram of methicillin per ml were found on the chests of only 3 of 80 (4%) patients before cardiac surgery, whereas these highly resistant staphylococci were isolated from the chest wounds of 43 of 80 (54%) patients 5 days postoperatively. The percentage of patients colonized with methicillin-resistant S. epidermidis increased with time postoperatively. Methicillin-resistant postoperative isolates also contained organisms resistant to other antibiotics frequently used during these patients' hospitalizations. The percentages of patients with organisms resistant to various antibiotics were: nafcillin (100%), penicillin (100%), cephalothin (93%), cefamandole (80%), streptomycin (67%), and gentamicin (20%). Preoperative methicillin-susceptible isolates were generally susceptible to other antibiotics. Two patients with S. epidermidis prosthetic valve endocariditis caused by multiple antibiotic-resistant isolates were among the study patients. Antibiotic susceptibility patterns of each isolate from these two patients were identical to those of postoperative chest isolates from the same patient.