Performance and impact of a multiplex PCR in ICU patients with ventilator-associated pneumonia or ventilated hospital-acquired pneumonia.

BACKGROUND: Early appropriate antibiotic therapy reduces morbidity and mortality of severe pneumonia. However, the emergence of bacterial resistance requires the earliest use of antibiotics with the narrowest possible spectrum. The Unyvero Hospitalized Pneumonia (HPN, Curetis) test is a multiplex PCR (M-PCR) system detecting 21 bacteria and 19 resistance genes on respiratory samples within 5 h. We assessed the performance and the potential impact of the M-PCR on the antibiotic therapy of ICU patients. METHODS: In this prospective study, we performed a M-PCR on bronchoalveolar lavage (BAL) or plugged telescoping catheter (PTC) samples of patients with ventilated HAP or VAP with Gram-negative bacilli or clustered Gram-positive cocci. This study was conducted in 3 ICUs in a French academic hospital: the medical and infectious diseases ICU, the surgical ICU, and the cardio-surgical ICU. A multidisciplinary expert panel simulated the antibiotic changes they would have made if the M-PCR results had been available. RESULTS: We analyzed 95 clinical samples of ventilated HAP or VAP (72 BAL and 23 PTC) from 85 patients (62 males, median age 64 years). The median turnaround time of the M-PCR was 4.6 h (IQR 4.4-5). A total of 90/112 bacteria were detected by the M-PCR system with a global sensitivity of 80% (95% CI, 73-88%) and specificity of 99% (95% CI 99-100). The sensitivity was better for Gram-negative bacteria (90%) than for Gram-positive cocci (62%) (p = 0.005). Moreover, 5/8 extended-spectrum beta-lactamases (CTX-M gene) and 4/4 carbapenemases genes (3 NDM, one oxa-48) were detected. The M-PCR could have led to the earlier initiation of an effective antibiotic in 20/95 patients (21%) and to early de-escalation in 37 patients (39%) but could also have led to one (1%) inadequate antimicrobial therapy. Among 17 empiric antibiotic treatments with carbapenems, 10 could have been de-escalated in the following hours according to the M-PCR results. The M-PCR also led to 2 unexpected diagnosis of severe legionellosis confirmed by culture methods. CONCLUSIONS: Our results suggest that the use of a M-PCR system for respiratory samples of patients with VAP and ventilated HAP could improve empirical antimicrobial therapy and reduce the use of broad-spectrum antibiotics.

Within-a-Day Detection and Rapid Characterization of Carbapenemase by Use of a New Carbapenem Inactivation Method-Based Test, CIMplus.

The dissemination of carbapenemase-producing Enterobacteriaceae (CPE) is a major threat to public health. Rapid and accurate detection of CPE is essential for initiating appropriate antimicrobial treatment and establishing infection control measures. The carbapenem inactivation method (CIM), which has good sensitivity and specificity but a detection time of 20 h, was recently described. In this study, we evaluated the performances of a new version, the CIMplus test, which allows detection of carbapenemases in 8 h and characterization of carbapenemase classes, according to the Ambler classification, in 20 h. A panel of 110 carbapenem-resistant Enterobacteriaceae strains, including 92 CPE strains (with NDM, VIM, IMP, KPC, GES, OXA-48, and OXA-48-like enzymes), was used to evaluate test performance. Carbapenemase activity was detected at 8 h and 20 h. Characterization of carbapenemase classes, using specific inhibitors, was possible in 20 h. The CIMplus test had sensitivities of 95.7% and 97.8% at 8 h and 20 h, respectively, and a specificity of 94.4%, independent of the culture duration. Using a decision algorithm, this test was successful in identifying the carbapenemase class for 98.9% of tested CPE isolates (87/88 isolates). In total, the characterization was correct for 100%, 96.9%, and 100% of Ambler class A, B, and D isolates, respectively. Therefore, this test allows detection of carbapenemase activity in 8 h and characterization of carbapenemase classes, according to the Ambler classification, in 20 h. The CIMplus test represents a simple, affordable, easy-to-read, and accurate tool that can be used without any specific equipment.

Ecological impact of ciprofloxacin on commensal enterococci in healthy volunteers.

Background: The ecological impact of ciprofloxacin on commensal enterococci is unknown. Methods: Forty-eight healthy volunteers received ciprofloxacin from day (D) 0 to D14; stools were collected on D7, D14 and D42. Fluoroquinolone-susceptible and -resistant enterococci (FQ-SE and FQ-RE) were detected and quantified by culture, and identified by MALDI-TOF MS. The relative abundance of FQ-RE over FQ-SE was determined. The genetic basis of fluoroquinolone resistance was deciphered by partial sequencing of gyrA and parC genes. Clonal relatedness was determined by random amplification of polymorphic DNA PCR. Clinical trial no.: NCT00190151. Results: Enterococci were carried by 47/48 (98%) subjects. Total counts were reduced during ciprofloxacin therapy (4.0 and 3.9 log cfu/g on D7 and D14 versus 5.9 log cfu/g before and 6.9 log cfu/g after treatment; P < 0.05). Twenty-one out of 48 (44%) carried FQ-RE; among them, 21/21 carried Enterococcus faecium , 19 carried Enterococcus faecalis and 11 carried other species. Five out of 48 (10%) harboured FQ-RE (ciprofloxacin MIC >4 mg/L) before treatment (all E. faecium ), 6 on D7 (3 E. faecium and 3 E. faecalis ), 8 on D14 (4 E. faecium and 4 E. faecalis ) and 10 (21%) on D42 (9 E. faecium and 1 E. faecalis ). The relative abundance of FQ-RE increased from 44% on D0 to 73% and 75% on D7 and D14, respectively. No acquisition of fluoroquinolone resistance among endogenous D0 strains was evidenced. All (14/14) distinct Fluoroquinolone-resistant E. faecalis clones were gyrA / parC double mutants with high-level resistance (ciprofloxacin MIC >64 mg/L). In contrast, 34/35 E. faecium exhibited low-level resistance (ciprofloxacin MIC 4-32 mg/L) with no gyrA / parC mutation, but overexpressed the chromosomal Efm qnr gene. As compared with Fluoroquinolone-susceptible strains, Fluoroquinolone-resistant E. faecium were more frequently ampicillin resistant and Fluoroquinolone-resistant E. faecalis were more highly resistant to gentamicin. Conclusions: Although intrinsically poorly susceptible to fluoroquinolones, gut populations of enterococci are highly impacted both quantitatively and qualitatively by ciprofloxacin.

In vitro activity of ß-lactams in combination with avibactam against multidrug-resistant Pseudomonas aeruginosa, Stenotrophomonas maltophilia and Achromobacter xylosoxidans isolates from patients with cystic fibrosis.

The in vitro activity of anti-pseudomonal ß-lactams in combination with avibactam was evaluated against 54 multidrug-resistant non-fermenting Gram-negative bacilli isolated from cystic fibrosis patients. Avibactam increased and/or restored the antibacterial activities of ceftazidime and aztreonam against Pseudomonas aeruginosa and Stenotrophomonas maltophilia, respectively. No ß-lactam-avibactam combination was active against Achromobacter xylosoxidans.