Prevalence of Multidrug-resistant, Extensively Drug-resistant, and Pandrug-resistant Pseudomonas Aeruginosa in Different Clinical Samples in Tertiary Care Center

Objectives.To perform a molecular and epidemiologic investigation of multidrug-resistant (MDR)Acinetobacter baumanniiin an institution were polyclonal outbreaks have been observed and determine whether these polyclonal outbreaks had an endogenous origin or were caused by in-hospital patient-to-patient transmission.Design.Retrospective analysis of prospectively collected data.Setting.An epidemiologic and genotypic investigation of incident cases of MDRA. baumanniiinfection in an Israeli university tertiary care center.Patients.Hospitalized patients with MDRA. baumanniiisolated from clinical samples during a 13-week period, from April 15, 2003, through July 15, 2003.Intervention.All patients with new MDRA. baumanniiinfections were recruited, and isolates were typed using pulsed-field gel electrophoresis. Data on in-hospital movements and consultations were extracted from computerized databases. Quantification of transmission opportunities (TOPs), defined as encounters between an established carrier and a future carrier of MDRA. baumannii, and analysis of ward clusters were performed.Results.We studied 96 MDRA. baumanniiisolates, which belonged to 18 different pulsed-field gel electrophoresis clones. In 65% of cases, TOPs involving patients with the same clone were demonstrated, which is significantly greater than the number of TOPs involving patients with different clones (P= .01).Conclusion.Although outbreaks of MDRA. baumanniiinfection may be polyclonal, we believe that patient-to-patient transmission explains most cases of transmission. Polyclonal local outbreaks reflect several clonal outbreaks occurring simultaneously. The cause of polyclonal outbreaks ofA. baumanniiinfections clustered by ward and time remains to be explained.

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1597. Ceftolozane-Tazobactam and Meropenem Synergy Testing Against Multi-Drug and Extensively-Drug Resistant Pseudomonas aeruginosa

Open Forum Infectious Diseases ◽

10.1093/ofid/ofaa439.1777 ◽

2020 ◽

Vol 7 (Supplement_1) ◽

pp. S794-S795

Author(s):

Mary Francine P Chua ◽

Syeda Sara Nida ◽

Jerry Lawhorn ◽

Janak Koirala

Keyword(s):

Pseudomonas Aeruginosa ◽

Synergistic Effect ◽

Inhibitory Concentration ◽

Multidrug Resistant ◽

Additive Effect ◽

Teaching Hospitals ◽

Drug Resistant ◽

Extensively Drug Resistant ◽

Synergy Testing ◽

Concentration Indices

Abstract Background Multidrug-resistant (MDR) and extensively drug-resistant (XDR) Pseudomonas aeruginosa (PA) have limited therapeutic options for treatment. Ceftolozane/tazobactam is a newer anti-pseudomonal drug effective against resistant PA infections, however resistance against this drug has now also developed and is increasing. In this study, we explored the combination of ceftolozane/tazobactam (CT) and meropenem (MP) as a possible effective regimen against MDR and XDR PA. Methods We obtained 33 non-duplicate isolates of MDR and XDR PA grown from blood, urine and respiratory samples collected from patients admitted between 2015 and 2019 at our two affiliate teaching hospitals. MDR PA was defined as resistance to 3 or more classes of anti-pseudomonal antibiotics, and XDR PA as resistance to all but two or less classes of anti-pseudomonal antibiotics. Antimicrobial preparations of both MP and CT were made according to manufacturer instructions. Susceptibility testing was performed using the checkerboard method in accordance to CLSI guidelines (CLSI M100, 2017). The ATCC 27853 strain of PA used as control. Synergy, additive effect, indifference and antagonism were defined as FIC (fractional inhibitory concentration) indices of ≤0.5, >0.5 to <1, >1 to <4, and >4, respectively. Results Thirteen (39%) of 33 PA isolates were classified as XDR, while 20 (61%) PA isolates were MDR. All isolates were resistant to MP (MIC50 >32 ug/mL), while only 2 (6%) isolates were susceptible to CT (MIC50 64 ug/mL). A synergistic effect was seen in 9 (27.3%) of PA isolates (FIC index range 0.28 to 0.5)— 2 of which were XDR PA, and 7 were MDR PA. An additive effect was seen in 12 (36.4%), with indifference seen in 12 (36.4%) of isolates. In this study, no antagonism was seen when CT and MP were combined. Conclusion When used in combination, CT and MP can exert a synergistic effect against MDR and XDR PA. Additive effect and indifference can also be seen when both antibiotics were used. Moreover, there was no antagonism seen when both antibiotics were combined. This study shows that the use of CT and MP in combination may be an option against XDR and MDR PA infections. Disclosures All Authors: No reported disclosures

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Antimicrobial Activity of Ceftazidime-Avibactam Tested against Multidrug-Resistant Enterobacteriaceae and Pseudomonas aeruginosa Isolates from U.S. Medical Centers, 2013 to 2016

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.01045-17 ◽

2017 ◽

Vol 61 (11) ◽

Cited By ~ 52

Author(s):

Helio S. Sader ◽

Mariana Castanheira ◽

Dee Shortridge ◽

Rodrigo E. Mendes ◽

Robert K. Flamm

Keyword(s):

Pseudomonas Aeruginosa ◽

Multidrug Resistant ◽

Drug Resistant ◽

Large Collection ◽

Content Type ◽

Negative Results ◽

Medical Centers ◽

Extensively Drug Resistant ◽

Genes Encoding

ABSTRACT The in vitro activity of ceftazidime-avibactam and many comparator agents was determined against various resistant subsets of organisms selected among 36,380 Enterobacteriaceae and 7,868 Pseudomonas aeruginosa isolates. The isolates were consecutively collected from 94 U.S. hospitals, and all isolates were tested for susceptibility by reference broth microdilution methods in a central monitoring laboratory (JMI Laboratories). Enterobacteriaceae isolates resistant to carbapenems (CRE) and/or ceftazidime-avibactam (MIC ≥ 16 μg/ml) were evaluated for the presence of genes encoding extended-spectrum β-lactamases and carbapenemases. Ceftazidime-avibactam inhibited >99.9% of all Enterobacteriaceae at the susceptible breakpoint of ≤8 μg/ml and was active against multidrug-resistant (MDR; n = 2,953; MIC50/90, 0.25/1 μg/ml; 99.2% susceptible), extensively drug-resistant (XDR; n = 448; MIC50/90, 0.5/2 μg/ml; 97.8% susceptible), and CRE (n = 513; MIC50/90, 0.5/2 μg/ml; 97.5% susceptible) isolates. Only 82.2% of MDR Enterobacteriaceae (n = 2,953) and 64.2% of ceftriaxone-nonsusceptible Klebsiella pneumoniae (n = 1,063) isolates were meropenem susceptible. Among Enterobacter cloacae (22.2% ceftazidime nonsusceptible), 99.8% of the isolates, including 99.3% of the ceftazidime-nonsusceptible isolates, were ceftazidime-avibactam susceptible. Only 23 of 36,380 Enterobacteriaceae (0.06%) isolates were ceftazidime-avibactam nonsusceptible, including 9 metallo-β-lactamase producers and 2 KPC-producing strains with porin alteration; the remaining 12 strains showed negative results for all β-lactamases tested. Ceftazidime-avibactam showed potent activity against P. aeruginosa (MIC50/90, 2/4 μg/ml; 97.1% susceptible), including MDR (MIC50/90, 4/16 μg/ml; 86.5% susceptible) isolates, and inhibited 71.8% of isolates nonsusceptible to meropenem, piperacillin-tazobactam, and ceftazidime (n = 628). In summary, ceftazidime-avibactam demonstrated potent activity against a large collection (n = 44,248) of contemporary Gram-negative bacilli isolated from U.S. patients, including organisms resistant to most currently available agents, such as CRE and meropenem-nonsusceptible P. aeruginosa.

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Evaluation of ceftazidime/avibactam for serious infections due to multidrug-resistant and extensively drug-resistant Pseudomonas aeruginosa

Journal of Global Antimicrobial Resistance ◽

10.1016/j.jgar.2018.07.010 ◽

2018 ◽

Vol 15 ◽

pp. 136-139 ◽

Cited By ~ 14

Author(s):

Olga Rodríguez-Núñez ◽

Marco Ripa ◽

Laura Morata ◽

Cristina de la Calle ◽

Celia Cardozo ◽

...

Keyword(s):

Pseudomonas Aeruginosa ◽

Multidrug Resistant ◽

Drug Resistant ◽

Extensively Drug Resistant ◽

Serious Infections

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Epidemiology of Nosocomial Outbreaks: 14-Year Experience at a Tertiary-Care Center

Infection Control and Hospital Epidemiology ◽

10.1086/501800 ◽

2000 ◽

Vol 21 (8) ◽

pp. 527-529 ◽

Cited By ~ 6

Author(s):

Luis Ostrosky-Zeichner ◽

Rosa Baez-Martinez ◽

M. Sigfrido Rangel-Frausto ◽

Samuel Ponce-de-León

Keyword(s):

Intensive Care Unit ◽

Pseudomonas Aeruginosa ◽

Intensive Care ◽

Nosocomial Infections ◽

Care Center ◽

Tertiary Care ◽

Tertiary Care Center ◽

Common Organism ◽

Overall Mortality

Twelve nosocomial outbreaks over 14 years at a tertiary-care center in Mexico are described. Overall mortality was 25.8%, one half due to pneumonia. The most common organism was Pseudomonas aeruginosa. Incidence was three outbreaks per 10,000 discharges; outbreak-related infections comprised 1.56% of all nosocomial infections. Incidence in the intensive care unit was 10-fold higher.

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