Susceptibility pattern of oral antimicrobials in uncomplicated UTI: Does fosfomycin still stand effective?

Comprehensive analysis of the bacterial spectrum for enhanced clinical insight in microbial ureteral stent colonization, uncomplicated urinary tract infections and catheter-associated urinary tract infections: a principal component analysis-based literature review

PURPOSE

Controversies exist regarding the prevailing spectrum of microorganisms in microbial ureteral stent colonization (MUSC) and their clinical significance. The aim of this comprehensive review is to determine the predominant microbial spectrum in patients with an indwelling ureteral stent in comparison to catheter-associated urinary tract infections (CAUTI) and uncomplicated urinary tract infections (UTI).

METHODS

Google scholar, PubMed, Embase, Medline, and Cochrane literature databases were searched from inception to April 2022 to identify manuscripts on MUSC, uncomplicated UTI and CAUTI. A principal component analysis (PCA) was performed to identify patterns of the pathogen spectrum of the different groups.

RESULTS

We included 29 studies on MUSC, 28 studies on uncomplicated UTI and 23 CAUTI studies. The proportion of Staphylococci, Enterococci and Candida were significantly higher in MUSC and stent associated bacteriuria compared to their proportion in uncomplicated UTIs where E. coli dominates. By comparing MUSC, CAUTI and UTI with a PCA, the detected pathogen spectrum exhibited clearly distinguishable trends in the frequency of the main isolated pathogens influencing these three groups of urinary tract infections. With respect to MUSC and UTI, their 95% confidence interval ellipse only showed minimal overlap emphasizing that the spectrum of pathogens in the two groups is clearly distinct.

CONCLUSIONS

The frequency of detection of Staphylococci, Enterococci and Candida is more common in MUSC as compared to UTI. Thus, patients with indwelling ureteral stents should undergo an antimicrobial prophylaxis targeting this microbial spectrum in case of further surgery.

Sensitivity Profile of Fosfomycin, Nitrofurantoin, and Co-trimoxazole Against Uropathogens Isolated From UTI Cases in a Secondary Care Center, KSA

Background Fosfomycin, nitrofurantoin, and co-trimoxazole are cheap and effective first-line oral antimicrobials in cases of uncomplicated cystitis in males and non-pregnant females. Fosfomycin and nitrofurantoin are called urinary antiseptics because these two drugs are primarily excreted in the kidney and concentrated in the urine without systemic effect. The present study was designed to evaluate the in vitro activities of fosfomycin, nitrofurantoin, and co-trimoxazole against uropathogens isolated at King Khalid Hospital Al-Majmaah, KSA. Methods The study was conducted at the King Khalid Hospital Al Majmaah, KSA, from September 1, 2021, until February 28, 2022. The patients' urine samples were inoculated on the Cystein Lactose Electrolytes Deficient (CLED) medium, and uropathogens were isolated. The organisms' identification and sensitivity testing against cotrimoxazole, fosfomycin, and nitrofurantoin was conducted using a Microscan automated analyzer, the MicroScan WalkAway Beckman Coulter, Sacramento, CA, USA. Results The study comprised non-repeat 137 patients who were either admitted to the hospital or treated as outpatients, yielding a total of 147 isolates. Nitrofurantoin showed a lower resistance rate, around 20% (n = 29), followed by fosfomycin at 23% (n = 34). The resistance rate of cotrimoxazole was 43% (n = 63). Overall, nitrofurantoin and fosfomycin showed relatively lower resistance against all isolates. Conclusions Being cheap and effective, we propose that fosfomycin and nitrofurantoin be used as first-line treatments in patients presenting with uncomplicated UTIs.

Susceptibility to first choice antimicrobial treatment for urinary tract infections to Escherichia coli isolates from women urine samples in community South Brazil

E. coli is the main pathogen of UTI. It is important to be aware the local epidemiological data for an appropriate initial treatment. Resistance to antimicrobial agents has increased, especially to first-choice antibiotics in the treatment of cystitis. There are few studies on the sensivity profile of community uropathogen in our region.

OBJECTIVE

To characterize antimicrobials the sensitivity profile to E. coli isolated from urocultures of women treated at Basic Health Units and Emergency Care Units of Londrina- Paraná- Brazil during a period of 12 months (June 1, 2016 to June 1, 2017).

METHODOLOGY

A cross-sectional study was carried out from June 2016 to June 2017. All urine samples collected in the Basic Health Units and Emergency Departments in the city of Londrina (Paraná State, Brazil) were sent to a Central Laboratory where the identification and antimicrobial susceptibility testing were performed. Clinical Laboratory Standards Institute (CLSI) breakpoints were used for the interpretation of susceptibility testing results.

RESULTS

56,555 urine cultures were performed in the period, of which 8,832 were positive, of which 5,377 were women. Of these samples, 4.7% were enterobacteria producing extended-spectrum beta-lactamases (ESBL) and 15.5% resistant to quinolones. TMP- SMX was resistant in more than 30% of the samples in all age groups. Among quinolone-resistant isolates, resistance to cephalothin, ampicillin and sulfamethoxazole-trimethoprim was greater than 60%. Nitrofurantoin was the only antimicrobial that showed 90% of sensitivity.

CONCLUSION

The antimicrobials sensitivity profile was similar to that reported in the literature, with TMP- SMX resistance greater than 30% in the studied samples. Nitrofurantoin maintains high sensitivity rates greater than 90%. Resistance to quinolones increases proportionally with age, as well ESBL.

Evaluation of in vitro activity of fosfomycin, and synergy in combination, in Gram-negative bloodstream infection isolates in a UK teaching hospital

Introduction. Fosfomycin has retained activity against many multi-drug resistant (MDR) Gram-negatives, and may be useful against extended spectrum beta-lactamase (ESBL) producing and carbapenem-resistant Enterobacterales to improve clinical outcomes.Hypothesis/Gap Statement. There are few data from the UK on the susceptibility of invasive Gram-negative isolates to fosfomycin, especially in the era of increasing use of oral fosfomycin for urinary tract infections (UTIs).Aim. We evaluated fosfomycin susceptibility against 100 consecutive Gram-negative bloodstream isolates, both individually, and in combination with other mechanistically similar and differing antibiotics. The aim was to investigate the synergy between antibiotic combinations against several E. coli, K. pneumoniae and P. aeruginosa isolates with variable levels of resistance.Methodology. Disc diffusion and MIC test strip methods applying revised EUCAST guidelines for Fosfomycin were used, followed by the MTS™ 'cross synergy' method for 'resistant' isolates as defined below: (a) Fosfomycin resistant by MIC test strip; (b) MDR isolates defined as being resistant to ≥3 classes of antibiotics (based on routine sensitivity testing; beta lactams were considered as a single class), and/or (c) AMP C or ESBL or carbapenemase producers (or carbapenem resistant). FIC Index (Fractional Inhibitory Concentration Index) calculations were used to interpret findings, whereby: FIC = (MICA combination A+B/ MIC agent A) + (MICB combination A+B/ MIC agent B). A result of ≤0.5 was taken to indicate 'synergy', >0.5 and ≤1.0 to indicate 'additive' effect, >1.0 and ≤4.0 to indicate 'indifference', and >4.0 to indicate 'antagonism'.Results. We found that 95/100 isolates were susceptible to fosfomycin by MIC test strip, with 88/100 isolates susceptible to fosfomycin by disc, based on EUCAST guideline breakpoints. A total of 30/100 isolates (the more 'resistant' of the 100) were eligible for synergy testing according to our definitions (see Methodology), with the remaining 70 isolates not tested further. Seventeen out of 30 were MDR, 2/30 were AMP C producers and 9/30 were ESBL producers. Overall, 34/300 (11 %) of all combination tests showed synergy and 161/300 (54 %) were additive. Synergy was most commonly detected between fosfomycin and beta-lactam antibiotics, including piperacillin/tazobactam (10/30; 33 %), ceftazidime/avibactam (10/30; 30 %), and temocillin (8/30; 27 %). An additive effect was most commonly detected with aztreonam (25/30; 83 %) and meropenem (25/30; 83 %), but 100 % indifference was found with tigecycline (30/30). No antagonism was identified with any antibiotic combination.Conclusion. Fosfomycin non-susceptibility by MIC test strip was unusual. Synergy was variable when combining fosfomycin with other antibiotics against the more 'resistant' isolates. Synergistic/additive effects were detected for beta-lactam/fosfomycin combinations in >80 % of all such combinations, suggesting beta-lactams may be the preferred partner for fosfomycin. Agents with a discordant site of action were more likely to result in indifference. Antagonism was not detected.

A global perspective on improving patient care in uncomplicated urinary tract infection: Expert consensus and practical guidance

BACKGROUND

Uncomplicated urinary tract infections (uUTIs) are a common problem in women. Management is mainly based on empirical prescribing, but there are concerns about overtreatment and antimicrobial resistance (AMR), especially in patients with recurrent uUTIs.

METHODS

A multidisciplinary panel of experts met to discuss diagnosis, treatment, prevention, guidelines, AMR, clinical trial design, and the impact of COVID-19 on clinical practice.

RESULTS

Symptoms remain the cornerstone of uUTI diagnosis, and urine culture is necessary only when empirical treatment fails, or rapid recurrence of symptoms or AMR is suspected. Specific antimicrobials are first-line therapy (typically nitrofurantoin, fosfomycin, trimethoprim-sulfamethoxazole, and pivmecillinam; dependent on availability and local resistance data). Fluoroquinolones are not first-line options for uUTIs due primarily to safety concerns, but also rising resistance rates. High-quality data to support most non-antimicrobial approaches are lacking. Local AMR data specific to community-acquired uUTIs are needed, but representative information is difficult to obtain; instead, identification of risk factors for AMR can provide a basis to guide empirical antimicrobial prescribing. The COVID-19 pandemic has impacted management of uUTIs in some countries and may have long-lasting implications for future models of care.

CONCLUSIONS

The management of uUTIs in women can be improved without increasing complexity, including simplified diagnosis, and empirical antimicrobial prescribing based on patient characteristics, including review of recent antimicrobial use and past pathogen resistance profiles, drug availability, and guidelines. Current data for non-antimicrobial approaches are limited. The influence of COVID-19 on telehealth could provide an opportunity to enhance patient care in the long term.