Antibacterial activity of fosfomycin against uropathogens

Effect of Colistin, Fosfomycin and Meropenem/Vaborbactam on Carbapenem-Resistant Enterobacterales in Egypt: A Cross-Sectional Study

Purpose

The increasing multi-drug carbapenem resistance among Enterobacterales are a severe health problem limiting therapeutic options and worsen the prognosis. This study characterizes carbapenemase genes and integrons among uropathogenic carbapenem resistant Enterobacterales (CRE) isolates recovered from Mansoura University Hospitals and evaluates the effect of colistin, fosfomycin and meropenem-vaborbactam on these isolates.

Patients and Methods

A total of 200 Enterobacterales isolates were collected from patients with urinary tract infections. Antimicrobial susceptibility testing was performed by the disc diffusion method. Colistin susceptibility was tested using the broth microdilution method and fosfomycin and meropenem/vaborbactam susceptibility were tested by MIC Test Strips. Carbapenem resistant isolates were screened for carbapenemase activity phenotypically using the modified carbapenem inactivation method and EDTA-modified carbapenem inactivation method and genotypically by multiplex PCR. Integrons class 1 and 2 and fosA gene were assayed by PCR. Data were statistically analyzed using the Statistical Package for Social Sciences (SPSS) version 16. The Chi-square or Fisher’s exact test was used to compare groups, as appropriate.

Results

Ninety-two Enterobacterales isolates were resistant to meropenem (46%); 52 E. coli and 40 K. pneumoniae strains. All CRE isolates were multi-drug resistant (MDR). Sensitivity of CRE isolates to colistin, fosfomycin and meropenem/vaborbactam were 67.4%, 82.6% and 58.7%, respectively. Carbapenemase genes were detected by multiplex PCR in 69.6% of CRE isolates (Carbapenemase producing Enterobacterales (CPE) mainly bla_NDM (37%). CPE isolates were significantly more resistant to meropenem/vaborbactam than non-CPE isolates; 51.6% vs 17.8%, respectively (P = 0.003) especially bla_NDM carrying isolates (70.6%). Class 1 integrons and fosA gene were detected in 91.3% and 11.9% of CRE isolates, respectively.

Conclusion

This study revealed that about half of the uropathogenic Enterobacterales isolates were MDR CRE. Carbapenemase gene bla_NDM was the main gene among CRE isolates. Meropenem/vaborbactam sensitivity was significantly higher on non-CPE than CPE isolates and limited by the predominance of bla_NDM.

Analysis of the spectrum and antibiotic resistance of uropathogens in outpatients at a tertiary hospital

The objective of this study was to analyse the distribution and antimicrobial resistance of bacterial uropathogens isolated from outpatients at Henan Provincial People's Hospital. A total of 1419 samples from 823 newly diagnosed and 596 recurrent UTI outpatients culture positive. Escherichia coli was the most common uropathogen. Compared with the recurrent group, the newly diagnosed group had a higher isolation rate of E. coli and Enterobacter cloacae but a lower isolation rate of Klebsiella pneumoniae, Pseudomonas aeruginosa and Acinetobacter spp. Except for P. aeruginosa, the resistance of Gram-negative bacteria to most antibiotics was less than 30%. All Enterococcus and Staphylococcus spp. were sensitive to linezolid, vancomycin and teicoplanin. Both Gram-negative and -positive bacteria exhibited high susceptibility to fosfomycin. Uropathogens isolated from recurrent outpatients had higher resistance rates than did those isolated from newly diagnosed outpatients. Our study indicated that fosfomycin might be an excellent treatment option for outpatients with UTIs.

The Activity of Fosfomycin Against Extended-Spectrum Beta-Lactamase-Producing Isolates of Enterobacteriaceae Recovered from Urinary Tract Infections: A Single-Center Study Over a Period of 12 Years

Despite global efforts to tackle resistance in extended-spectrum beta-lactamase (ESBL)-producing isolates via old antibiotics, there are limited data on the efficacy of fosfomycin-an old oral antibiotic-against Enterobacteriaceae in the Middle East. The purpose of this study was to evaluate the in vitro activity of fosfomycin against urinary ESBL-producing isolates of Enterobacteriaceae. Between 2004 and 2015, 363 isolates of ESBL-producing Enterobacteriaceae were recovered from high-risk patients suffering from cardiac disorders and were subjected to polymerase chain reaction using specific primers for the bla_TEM, bla_SHV, and bla_CTX-M genes. Antibiotic susceptibility testing was performed for fosfomycin and other antibiotic comparators. For the isolates considered nonsusceptible to fosfomycin by disk diffusion, the minimum inhibitory concentration (MIC) was determined. The susceptibility rate to fosfomycin remained almost steady (90-100%) over a 12-year period, although it fluctuated vis-à-vis ciprofloxacin (0-54%), trimethoprim/sulfamethoxazole (9.1-31.7%), and nitrofurantoin (41.7-100%). Of all the antibiotics tested, fosfomycin was the most active antimicrobial agent (97%) against the ESBL-positive isolates. Fosfomycin maintained higher activity against ESBL-Escherichia coli than against ESBL-Klebsiella pneumoniae. Only 11 (3%) isolates were not susceptible to fosfomycin according to disk diffusion and they had MICs greater than 1,024 mg/ml. All of the fosfomycin-nonsusceptible isolates were positive for the bla_CTX-M gene (100%), while 5 (45.4%) and 3 (27.3%) of the isolates harbored the bla_TEM and bla_SHV genes, respectively. We showed that fosfomycin had a numerically higher susceptibility rate than the other antibiotics against the ESBL-producing isolates of the most common Enterobacteriaceae. Given its low resistance rate and oral administration, fosfomycin may be deemed a promising antibiotic for the treatment of urinary tract infections caused by ESBL-producing Enterobacteriaceae.

Assessment of Fosfomycin for Complicated or Multidrug-Resistant Urinary Tract Infections: Patient Characteristics and Outcomes

BACKGROUND

Bacterial resistance among uropathogens is on the rise and has led to a decreased effectiveness of oral therapies. Fosfomycin tromethamine (fosfomycin) is indicated for uncomplicated urinary tract infections (UTIs) and displays in vitro activity against multidrug-resistant (MDR) isolates; however, clinical data assessing fosfomycin for the treatment of complicated or MDR UTIs are limited.

METHODS

We conducted a retrospective evaluation of patients who received ≥1 dose of fosfomycin between January 2009 and September 2015 for treatment of a UTI. Patients were included if they had a positive urine culture and documented signs/symptoms of a UTI.

RESULTS

Fifty-seven patients were included; 44 (77.2%) had complicated UTIs, 36 (63.2%) had MDR UTIs, and a total of 23 (40.4%) patients had a UTI that was both complicated and MDR. The majority of patients were female (66.7%) and elderly (median age, 79 years). Overall, the most common pathogens isolated were Escherichia coli (n = 28), Enterococcus spp. (n = 22), and Pseudomonas aeruginosa (n = 8). Twenty-eight patients (49.1%) were clinically evaluable; the preponderance achieved clinical success (96.4%). Fifteen out of 20 (75%) patients with repeat urine cultures had a microbiological cure.

CONCLUSIONS

This retrospective study adds to the limited literature exploring alternative therapies for complicated and MDR UTIs with results providing additional evidence that fosfomycin may be an effective oral option.