Global epidemiology and clinical outcomes of carbapenem-resistant Pseudomonas aeruginosa and associated carbapenemases (POP): a prospective cohort study

BACKGROUND

Carbapenem-resistant Pseudomonas aeruginosa (CRPA) is a global threat, but the distribution and clinical significance of carbapenemases are unclear. The aim of this study was to define characteristics and outcomes of CRPA infections and the global frequency and clinical impact of carbapenemases harboured by CRPA.

METHODS

We conducted an observational, prospective cohort study of CRPA isolated from bloodstream, respiratory, urine, or wound cultures of patients at 44 hospitals (10 countries) between Dec 1, 2018, and Nov 30, 2019. Clinical data were abstracted from health records and CRPA isolates were whole-genome sequenced. The primary outcome was 30-day mortality from the day the index culture was collected. We compared outcomes of patients with CRPA infections by infection type and across geographic regions and performed an inverse probability weighted analysis to assess the association between carbapenemase production and 30-day mortality.

FINDINGS

We enrolled 972 patients (USA n=527, China n=171, south and central America n=127, Middle East n=91, Australia and Singapore n=56), of whom 581 (60%) had CRPA infections. 30-day mortality differed by infection type (bloodstream 21 [30%] of 69, respiratory 69 [19%] of 358, wound nine [14%] of 66, urine six [7%] of 88; p=0·0012) and geographical region (Middle East 15 [29%] of 52, south and central America 20 [27%] of 73, USA 60 [19%] of 308, Australia and Singapore three [11%] of 28, China seven [6%] of 120; p=0·0002). Prevalence of carbapenemase genes among CRPA isolates also varied by region (south and central America 88 [69%] of 127, Australia and Singapore 32 [57%] of 56, China 54 [32%] of 171, Middle East 27 [30%] of 91, USA ten [2%] of 527; p<0·0001). KPC-2 (n=103 [49%]) and VIM-2 (n=75 [36%]) were the most common carbapenemases in 211 carbapenemase-producing isolates. After excluding USA patients, because few US isolates had carbapenemases, patients with carbapenemase-producing CRPA infections had higher 30-day mortality than those with non-carbapenemase-producing CRPA infections in both unadjusted (26 [22%] of 120 vs 19 [12%] of 153; difference 9%, 95% CI 3-16) and adjusted (difference 7%, 95% CI 1-14) analyses.

INTERPRETATION

The emergence of different carbapenemases among CRPA isolates in different geographical regions and the increased mortality associated with carbapenemase-producing CRPA infections highlight the therapeutic challenges posed by these organisms.

FUNDING

National Institutes of Health.

Polymyxin B-induced skin hyperpigmentation

Polymyxin B (PMB) is a potent antibiotic targeting gram-negative bacteria and is associated with serious side effects including nephrotoxicity, neurotoxicity, and hypersensitivity reactions. PMB is a therapeutic option for the management of infections caused by multi-drug-resistant (MDR) bacteria and used in combination with other antibiotics when options are limited. We describe the case of a 30-year-old female patient with a complex medical history who underwent a multi-visceral transplantation complicated by intra-abdominal infections. Subsequently, patient developed diffuse skin darkening after initiation of intravenous PMB for treatment of MDR Pseudomonas aeruginosa. Her skin hyperpigmentation was most prominent on her face and forearms. Hyperpigmentation peaked at around 2 weeks following PMB initiation and was discontinued after 3 weeks when the possibility of PMB hyperpigmentation was raised and other causes were ruled out. Skin biopsy showed hypermelanosis of the basal layer and melanin deposition in the dermis. Overall clinical picture was consistent with PMB-induced hyperpigmentation. The patient demonstrated some improvement in discoloration within 4 weeks of PMB discontinuation.

Screening for Zika virus in deceased organ donors in Florida

Zika virus (ZIKV) cases have been detected across the United States (US) and locally acquired cases have been reported in Florida. Currently, there are no ZIKV screening guidelines and no data on the incidence among organ donors in the US. This retrospective study was conducted at Jackson Memorial-Miami Transplant Institute. Positive ZIKV tests in local deceased organ donors were investigated from 6/2016 to 1/2017. We evaluated demographics and risk factors for ZIKV infection among organ donors and transplant outcomes among recipients of donors with positive ZIKV testing. One hundred forty-two donors were analyzed. Ten percent had traveled to ZIKV-endemic countries and 19% had outdoor occupations. Only 3% had positive ZIKV IGG. None had a positive ZIKV IGM or PCR. ZIKV-positive donors were more likely to have traveled to ZIKV-endemic countries (50% vs. 9%, P = .05). The kidneys from a ZIKV-positive donor were transplanted in our hospital with no 6-month rejection, graft failure, or death in the recipients. Our study demonstrated a low prevalence of ZIKV among deceased donors in our community. Despite local ZIKV transmission, ZIKV was more common in donors who traveled to ZIKV-endemic countries. This cohort demonstrated excellent outcomes in recipients of ZIKV IGG-positive donors. However, larger studies are needed.

In Vitro Discordance with In Vivo Activity: Humanized Exposures of Ceftazidime-Avibactam, Aztreonam, and Tigecycline Alone and in Combination against New Delhi Metallo-β-Lactamase-Producing Klebsiella pneumoniae in a Murine Lung Infection Model

The management of infections with New Delhi metallo-beta-lactamase-1 (NDM)-producing bacteria remains clinically challenging given the multidrug resistant (MDR) phenotype associated with these bacteria. Despite resistance in vitro, ceftazidime-avibactam previously demonstrated in vivo activity against NDM-positive Enterobacteriaceae Herein, we observed in vitro synergy with ceftazidime-avibactam and aztreonam against an MDR Klebsiella pneumoniae harboring NDM. In vivo, humanized doses of ceftazidime-avibactam monotherapy resulted in >2 log10 CFU bacterial reduction; therefore, no in vivo synergy was observed.