Etiology and antibiotic susceptibility of bacterial pathogens responsible for community-acquired urinary tract infections in Poland

The genetic background of antibiotic resistance among clinical uropathogenic Escherichia coli strains

The spreading mechanisms of antibiotic resistance are related to many bacterial and environment factors. The overuse of antibiotics is leading to an unceasing emergence of new multidrug resistant strains. This problem also concerns uropathogenic Escherichia coli strains, which is the most common pathogen causing urinary tract infections. The aim of this study was the genetic analysis of antibiotic resistance in comparison to the phenotypic background of E. coli strains. The characterized collection of E. coli strains isolated 10 years ago from the urine samples of patients with urinary tract infections was used for antimicrobial susceptibility testing (the disc diffusion method) and analysis of antibiotic resistance genes (PCR reaction, sequencing). Additionally, the presence of ESBL strains was analyzed. Fourteen genes were associated with resistance to beta-lactams, aminoglycosides, sulfonamides and quinolones. The genetic analysis revealed that bla_TEM-1 and sul2 were present in almost all of the studied strains. Other drug-resistance genes were very rare or non-existent. Otherwise, the phenotypic resistance to fluoroquinolones was well correlated with the genotypic background of the studied bacteria. The presence of particular genes and specific mutations indicate a high bacterial potential to multidrug resistance. On the other hand, it needs to be emphasized that the standard disk diffusion test for the routine antimicrobial susceptibility analysis is still the best way to estimate the current situation of bacterial drug-resistance.

The Usefulness of Chromogenic Media for Qualitative and Semi-Quantitative Diagnostic of Urinary Tract Infections

The aim of this study was to evaluate the usefulness of chromogenic media for isolation of bacteria from urine and direct identification of UTI pathogens. A total of 100 urine specimens were inoculated on blood agar and MacConkey agar as a reference method and on the following media to be tested: chromID^® CPS^® Elite (CPSE, bioMérieux), CHROMagar™ Orientation (BioMaxima), BD CHROMagar Orientation Medium (ORI, Becton Dickinson), CHROMagar™ Orientation (ORIE, Graso) and Brillance UTI Clarity Agar (UTI C, Oxoid). After a 24-hour incubation period, 47 Gram-positive cocci and 62 Gram-negative rods were observed. The specificity and sensitivity of all chromogenic media was 97.3% and 93.5% respectively for qualitative diagnostic; and 81.9% and 81.3% respectively for semi-quantitative diagnostic. The mean PPV and NPV of the chromogenic media were 98.7% and 87.7% for qualitative UTI diagnostic, and 90.9% and 71.9% respectively for semi-quantitative diagnostic.

Community-acquired Lower Urinary Tract Infections: Etiology, Antimicrobial Resistance, and Treatment Results in Female Patients

Background/Purpose:

Most community-acquired urinary tract infections (UTIs) are usually treated empirically. The knowledge of antibiotic resistance patterns of the microorganisms causing UTI is essential for defining the empirical treatment.

Objective:

The aim of the present study is to determine the distribution of bacterial strains isolated from lower UTIs and their resistance patterns against commonly used antimicrobial agents and treatment results in female patients.

Subjects and Methods:

This is a retrospective analysis of medical case records of 90 female patients with lower UTI for a period of 4 years from January 2013 to December 2016 in a tertiary care hospital in the Trakya region of Turkey.

Results:

The most common causative agent was Escherichia coli (66.6% of cases) followed by Klebsiella pneumoniae (16.6%). Fosfomycin was the most active agent against E. coli (resistant isolates: 5.5%), followed by nitrofurantoin (resistant isolates: 7.4%). Extended-spectrum beta-lactamases (ESBLs) production was observed in 29 (32.2%) isolates (22 in E. coli, 6 in K. pneumoniae, and 1 in Enterobacter spp.). The antimicrobial resistance rates among ESBL-producing E. coli isolates for trimethoprim-sulfamethoxazole, ciprofloxacin, fosfomycin, and nitrofurantoin were 77.7%, 72.7%, 13.6%, and 18.2%, respectively (P < 0.05). The estimated microbiological eradication rates for nitrofurantoin and fosfomycin were 89.7% and 83.8%, respectively.

Conclusions:

The results of the present study indicate that nitrofurantoin and fosfomycin may be considered for empirical therapy of lower UTIs in Trakya region of Turkey.

Bacteriology in uncomplicated urinary tract infections in Norwegian general practice from 2001-2015

Background

Uncomplicated urinary tract infections in women are common, and urine samples from these patients are not routinely cultured. Empirical treatment is based on knowledge of resistance patterns for common uropathogens.

Aim

To evaluate the bacteriological findings and resistance patterns in urine samples from women with uncomplicated urinary tract infections, and to assess the relationship between antimicrobial use and resistance patterns from 2000–2015 in Norway.

Method

Bacteriology and resistance patterns were compared in 184 urine cultures from 2001, 406 urine cultures from 2010–2011 and 259 urine cultures from 2013–2015. Antibiotic use data from 2000–2015 were obtained from national databases.

Results

Escherichia coli (E. coli) was the main bacterial agent in 80% of the cultures. Staphylococcus saprophyticus (Staph. saprophyticus) represented 6–17%. For E. coli, resistance to mecillinam showed some variation but remained below 9%. There was negligible resistance to nitrofurantoin. Resistance to trimethoprim seemed to stabilise over the last 5 years at around 20%. Amoxicillin resistance had some variations, but remained stable around 30%. There was a steady rise in total consumption of selected antibiotics commonly used to treat urinary tract infections for the period 2000–2015.

Conclusion

Mecillinam and nitrofurantoin are both excellent first choices for empirical treatment of uncomplicated urinary tract infections. This study suggests that increasing resistance to trimethoprim challenges the rationale for its use as a first-line agent.

A Klebsiella pneumoniae antibiotic resistance mechanism that subdues host defences and promotes virulence

Klebsiella pneumoniae is an important cause of multidrug‐resistant infections worldwide. Recent studies highlight the emergence of multidrug‐resistant K. pneumoniae strains which show resistance to colistin, a last‐line antibiotic, arising from mutational inactivation of the mgrB regulatory gene. However, the precise molecular resistance mechanisms of mgrB‐associated colistin resistance and its impact on virulence remain unclear. Here, we constructed an mgrB gene K. pneumoniae mutant and performed characterisation of its lipid A structure, polymyxin and antimicrobial peptide resistance, virulence and inflammatory responses upon infection. Our data reveal that mgrB mutation induces PhoPQ‐governed lipid A remodelling which confers not only resistance to polymyxins, but also enhances K. pneumoniae virulence by decreasing antimicrobial peptide susceptibility and attenuating early host defence response activation. Overall, our findings have important implications for patient management and antimicrobial stewardship, while also stressing antibiotic resistance development is not inexorably linked with subdued bacterial fitness and virulence.

Antimicrobial Resistance Patterns in Women with Positive Urine Culture: Does Menopausal Status Make a Significant Difference?

Aim. Urinary tract infection (UTI) is considered one of the most common bacterial infections in women. The aim of this study was to investigate the types of uropathogens present, as well as the degree of antimicrobial drug resistance seen among premenopausal (n = 2748) and postmenopausal (n = 1705) women with uncomplicated UTI. Methods. Urinary samples (n = 4453) collected from women with UTI were analyzed in terms of uropathogens present. These were considered as positive if bacterial growth was ≥10⁵ colony forming units (CFUs)/mL. Susceptibility and resistance testing for commonly used antibiotics was subsequently assessed. Results. The most common uropathogens cultured from urine samples were Escherichia coli (65.5%), followed by Enterococcus faecalis (12.2%), Klebsiella pneumoniae (4.7%), and Proteus mirabilis (4.2%). The resistance to ampicillin exceeded 40%, independently of menopausal status. Of note, resistance to ciprofloxacin exceeded 25% among postmenopausal patients. Moreover, resistance of all uropathogens to commonly used antimicrobials was significantly higher in postmenopausal women. Conclusion. Due to the high resistance rate, ampicillin, ciprofloxacin, and the trimethoprim/sulfamethoxazole combination should be avoided in treating postmenopausal women affected by UTI without being indicated by initial urine culture report. Finally, cephalexin and cefuroxime are promising alternatives as initial treatment in postmenopausal women.