In Vitro Activities of Ceftazidime-Avibactam, Aztreonam-Avibactam, and a Panel of Older and Contemporary Antimicrobial Agents against Carbapenemase-Producing Gram-Negative Bacilli.

Among 177 carbapenemase-producing Gram-negative bacilli (108 KPC, 32 NDM, 11 IMP, 8 OXA-48, 4 OXA-181, 2 OXA-232, 5 IMI, 4 VIM, and 3 SME producers), aztreonam-avibactam was active against all isolates except two NDM producers with elevated MICs of 8/4 and 16/4 mg/liter; ceftazidime-avibactam was active against all KPC-, IMI-, SME-, and most OXA-48 group-producing isolates (93%) but not metallo-ß-lactamase producers. Among older and contemporary antimicrobials, the most active were colistin, tigecycline, and fosfomycin, with overall susceptibilities of 88%, 79%, and 78%, respectively.

Ceftolozane-tazobactam activity against clinical isolates of Pseudomonas aeruginosa from ICU patients with pneumonia: United States, 2015-2018.

OBJECTIVES: To report on the activity of ceftolozane-tazobactam and comparators against Pseudomonas aeruginosa isolates collected from hospitalized patients with pneumonia in US intensive care units (ICUs) between 2015 and 2018. Activity against all P. aeruginosa and common resistant phenotypes are described to better inform decision-making and support antimicrobial stewardship efforts. METHODS: In total, 781 P. aeruginosa isolates were collected from 28 US hospitals. These isolates were tested for susceptibility to ceftolozane-tazobactam and comparators by Clinical and Laboratory Standards Institute (CLSI) broth microdilution methodology using CLSI (2020) breakpoints. Phenotypes analysed included piperacillin-tazobactam-non-susceptible (NS), cefepime-NS, ceftazidime-NS, meropenem-NS and difficult-to-treat resistance (DTR). RESULTS: Ceftolozane-tazobactam was the most potent agent tested (minimum inhibitory concentration to inhibit 50% and 90% of isolates of 0.5 and 2 mg/L, respectively, inhibiting 97.2% at the susceptible breakpoint of ≤4 mg/L). Traditional first-line antipseudomonal ß-lactam antibiotics (piperacillin-tazobactam, cefepime and ceftazidime) demonstrated <33% susceptibility when P. aeruginosa was NS to one or more agent. Although escalation of therapy to meropenem is commonly employed clinically, meropenem susceptibility ranged from 33.6% to 44.9% if P. aeruginosa was NS to any traditional first-line antipseudomonal ß-lactam agent. Conversely, ceftolozane-tazobactam remained active against isolates that were NS to other agents, inhibiting 88.4% of isolates NS to piperacillin-tazobactam, 85.0% of isolates NS to cefepime and ceftazidime, and 90.3% of isolates NS to meropenem. Ceftolozane-tazobactam also maintained activity against 73.0% of DTR isolates. CONCLUSIONS: Ceftolozane-tazobactam maintained high activity against P. aeruginosa isolated from hospitalized patients with pneumonia in US ICUs, and had the greatest activity against isolates NS to one or more antipseudomonal ß-lactams and DTR isolates.

A practical UV source to induce Herpes simplex labialis lesions in the clinic.

BACKGROUND: Ultraviolet (UV) sources have been used to clinically induce herpes simplex lesions in the lips of susceptible individuals. METHODS: This study reports the optimization of a UV source for studies involving multiple clinical laboratory sites and subsequent clinical UV induction of cold sore lesions. We describe novel adaptations of a commercially available broadband UV phototherapy lamp that facilitate determination of individual's minimal erythemal dose (MED) and expose the lips with minimal risk of viral transmission to or between the volunteers and technicians. CLINICAL RESULTS: The source performed well in a clinical setting, with 171 of 386 subjects (44%) developing lesions, an induction rate similar to spectrally similar UV sources. CONCLUSIONS: The advantages of consistent and reproducible exposure geometry, additional UV shielding and biological hygiene achieved by our method significantly enhance the execution of UV-induced herpes simplex labialis studies.