In vitro susceptibility test practices with Haemophilus influenzae among college of American Pathologists survey participants in the United States

1993 ◽  
Vol 17 (1) ◽  
pp. 61-65 ◽  
Author(s):  
Gary V. Doern ◽  
Ronald N. Jones
1999 ◽  
Vol 123 (4) ◽  
pp. 285-289 ◽  
Author(s):  
Gary V. Doern ◽  
Angela B. Brueggemann ◽  
Michael A. Pfaller ◽  
Ronald N. Jones

Abstract Objective.—To assess the performance of clinical microbiology laboratories in the United States when conducting in vitro susceptibility tests with Streptococcus pneumoniae. Methods.—The results of a nationwide College of American Pathologists Proficiency Survey test sample, in which susceptibility testing of an isolate of S pneumoniae was performed, were assessed with respect to precision and accuracy. Results.—Wide variability was noted among participating laboratories with both minimum inhibitory concentration procedures and disk diffusion susceptibility tests when both methods were applied to S pneumoniae. Despite this high degree of variation, categorical interpretive errors were uncommon. Numerous laboratories reported results for antimicrobial agents that are not recommended by the National Committee for Clinical Laboratory Standards for tests with S pneumoniae. Conclusions.—Current susceptibility testing practices with S pneumoniae in the United States indicate limited precision and a tendency for laboratories to test and report results obtained with antimicrobial agents of questionable therapeutic value against this organism. Continued efforts to standardize susceptibility testing of S pneumoniae in the United States are warranted. In addition, modifications of existing interpretive criteria may be necessary.


Author(s):  
Jade L. L. Teng ◽  
Elaine Chan ◽  
Asher C. H. Dai ◽  
Gillian Ng ◽  
Tsz Tuen Li ◽  
...  

Both typhoidal and non-typhoidal salmonellae are included in the top 15 drug-resistant threats described by the Center for Disease Control and Prevention of the United States. There is an urgent need to look for alternative antibiotics for the treatment of Salmonella infections. We examined the in vitro susceptibilities of ceftolozane/tazobactam and six other antibiotics on typhoidal and non-typhoidal salmonellae, including isolates that are extended-spectrum β-lactamase (ESBL)-positive, using the broth microdilution test. Of the 313 (52 typhoidal and 261 non-typhoidal) Salmonella isolates tested, 98.7% were susceptible to ceftolozane/tazobactam. Based on the overall MIC 50/90 values, Salmonella isolates were more susceptible to ceftolozane/tazobactam (0.25/0.5 mg/L) compared to all other comparator agents: ampicillin (≥64/≥64 mg/L), levofloxacin (0.25/1 mg/L), azithromycin (4/16 mg/L), ceftriaxone (≤0.25/4 mg/L), chloramphenicol (8/≥64 mg/L) and trimethoprim/sulfamethoxazole (1/≥8 mg/L). When comparing the activity of the antimicrobial agents against non-typhoidal Salmonella isolates according to their serogroup, ceftolozane/tazobactam had the highest activity (100%) against Salmonella serogroups D, G, I and Q isolates, whereas the lowest activity (85.7%) was observed against serogroup E isolates. All the 10 ESBL-producing Salmonella (all non-typhoidal) isolates, of which 8 were CTX-M-55-producers and 2 were CTX-M-65-producers, were sensitive to ceftolozane/tazobactam albeit with a higher MIC 50/90 value (1/2 mg/L) than non-ESBL-producers (0.25/0.5 mg/L). In summary, our data indicate that ceftolozane/tazobactam is active against most strains of both typhoidal and non-typhoidal salmonellae and also active against ESBL-producing salmonellae.


2019 ◽  
Vol 6 (Supplement_2) ◽  
pp. S577-S578
Author(s):  
Dee Shortridge ◽  
Jennifer M Streit ◽  
Michael D Huband ◽  
Robert K Flamm

Abstract Background Delafloxacin (DLX) is an anionic fluoroquinolone (FQ) antimicrobial that was approved in 2017 by the United States (US) Food and Drug Administration for the treatment of acute bacterial skin and skin structure infections. DLX recently successfully completed a clinical trial for the treatment of community-acquired bacterial pneumonia (CABP). In the present study, in vitro susceptibility (S) results for DLX and comparator agents were determined for CABP pathogens including Streptococcus pneumoniae (SPN), Haemophilus influenzae (HI), H. parainfluenzae (HP) and Moraxella catarrhalis (MC) clinical isolates from US hospitals participating in the SENTRY Program during 2014–2018. Methods A total of 1,975 SPN, 1,128 HI, 684 MC, and 43 HP isolates were collected from community-acquired respiratory tract infections (CARTI) during 2014–2018 from US hospitals. Sites included only 1 isolate/patient/infection episode. Isolate identifications were confirmed at JMI Laboratories. Susceptibility testing was performed according to CLSI broth microdilution methodology, and CLSI (2019) breakpoints were applied where applicable. Other antimicrobials tested included levofloxacin (LEV) and moxifloxacin (MOX; not tested in 2015). Multidrug-resistant (MDR) SPN isolates were categorized as being nonsusceptible (NS) to amoxicillin-clavulanate, erythromycin, and tetracycline; other SPN phenotypes were LEV-NS or penicillin (PEN)-NS. β-Lactamase (BL) presence was determined for HI, HP, and MC. Results The activities of the 3 FQs are shown in the table. The most active agent against SPN was DLX, with the lowest MIC50/90 values of 0.015/0.03 mg/L. DLX activities were similar when tested against the MDR or PEN-NS for SPN phenotypes. LEV-NS isolates had DLX MIC50/90 results of 0.12/0.25 mg/L. DLX was the most active FQ against HI, HP, and MC. BL presence did not affect FQ MIC values for HI or MC; only 2 HP isolates were BL-positive. Conclusion DLX demonstrated potent in vitro antibacterial activity against SPN, HI, HP, and MC. DLX was active against MDR SPN that were NS to the agents commonly used as treatments for CABP. DLX had excellent activity against LEV-NS SPN. These data support the continued study of DLX as a potential treatment for CABP. Disclosures All authors: No reported disclosures.


2005 ◽  
Vol 49 (6) ◽  
pp. 2487-2489 ◽  
Author(s):  
Michael Green ◽  
Coburn Allen ◽  
John Bradley ◽  
Barry Dashefsky ◽  
Janet R. Gilsdorf ◽  
...  

ABSTRACT In vitro susceptibility testing of 2,797 group A streptococcus (GAS) isolates demonstrated that telithromycin was fully active against all macrolide-susceptible strains and among 80 of 115 macrolide-resistant GAS expressing the M phenotype. Telithromycin resistance was identified in 2 of 45 strains expressing the inducible macrolide-lincosamide-streptogramin B phenotype and four of nine isolates expressing the constitutive macrolide-lincosamide-streptogramin B resistance phenotype.


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