The analysis of microbial spectrum and antibiotic resistance of uropathogens isolated from patients with urinary stones

Distribution and antimicrobial resistance patterns of urinary pathogens in preoperative midstream urine cultures from Chinese patients with urinary calculi: a meta-analysis

BACKGROUND AND OBJECTIVE

This study comprehensively evaluates the distribution patterns and antimicrobial resistance profiles of urinary pathogens in Preoperative midstream urine cultures collected from patients with urinary calculi in China over the last two decades.

METHODS

A cross-sectional analysis of 41 studies was conducted. A systematic search across various databases, including Wanfang Data, CNKI, SinoMed, Embase, PubMed, and Web of Science, was carried out, covering the time period from 2002 to 2022. Using R 4.2.1 software, a meta-analysis was performed to assess heterogeneity using Cochran's Q test and the I2 statistic.

RESULTS

In the analysis of preoperative midstream urine cultures from Chinese patients with urinary calculi, gram-negative bacteria dominated at 69%, with Escherichia coli (43%), Klebsiella pneumoniae (8%), Proteus mirabilis (6%), Pseudomonas aeruginosa (5%), Acinetobacter baumannii (3%), and Enterobacter cloacae (4%) being prominent. Gram-positive organisms included Enterococcus faecalis (9%), Enterococcus faecium (5%), and Staphylococcus aureus (4%). Over time, proportions of Proteus mirabilis, Enterococcus faecalis, and Staphylococcus aureus decreased, while Klebsiella pneumoniae and Pseudomonas aeruginosa increased. Notably, Escherichia coli proportion reduced from 37 to 33% within the last two decades. Antimicrobial resistance analysis indicated declining resistance in E. coli (e.g., co-trimoxazole from 73 to 55%, gentamicin from 64 to 40%), but rising resistance in piperacillin and cefotaxime (34-60%). Enterococcus faecalis exhibited increasing resistance to ampicillin (5-69%), gentamicin (59-94%), and tetracycline (77-89%) over time, while resistance to levofloxacin and ciprofloxacin notably decreased (72-16% and 49-8%, respectively).

CONCLUSION

Over the past two decades, the proportion of gram-negative bacteria was declined, while the proportion of gram-positive bacteria increased. Escherichia coli remained the most common pathogen in the urine culture of patients with urinary calculi in China and the resistance of Escherichia coli to commonly used antibiotics increased. Clinicians should select appropriate antibiotics according to the results of urine culture and drug sensitivity test to reduce the occurrence of antibiotic resistance.

A 2-Year Audit on Antibiotic Resistance Patterns from a Urology Department in Greece

PURPOSE

The high incidence of urinary tract infections (UTIs), often in nosocomial environments, is a major cause of antimicrobial resistance (AMR). The dissemination of antibiotic-resistant infections results in very high health and economic burdens for patients and healthcare systems, respectively. This study aims to determine and present the antibiotic resistance profiles of the most common pathogens in a urology department in Greece.

METHODS

During the period 2019-2020, we included 12,215 clinical samples of blood and urine specimens that tested positive for the following pathogens: Escherichia coli, Enterococcus faecium, Enterococcus faecalis, Proteus mirabilis, Klebsiella pneumoniae, or Pseudomonas aeruginosa, as these are the most commonly encountered microbes in a urology department.

RESULTS

The analysis revealed a 22.30% mean resistance rate of E. coli strains with a 76.42% resistance to ampicillin and a 54.76% resistance rate to ciprofloxacin in the two-year period. It also showed an approximately 19% resistance rate of P. mirabilis strains and a mean resistance rate of 46.205% of K. pneumoniae strains, with a decreasing trend during the four semesters (p-value < 0.001), which presented an 80% resistance rate to ampicillin/sulbactam and 73.33% to ciprofloxacin. The resistance to carbapenems was reported to be 39.82%. The analysis revealed a 24.17% mean resistance rate of P. aeruginosa with a declining rate over the two-year period (p-value < 0.001). The P. aeruginosa strains were 38% resistant to fluoroquinolones and presented varying resistance against carbapenems (31.58% against doripenem and 19.79% against meropenem). Regarding the Enteroccocal strains, a 46.91% mean resistance was noted for E. faecium with 100% resistance to ampicillin, and a 24.247% mean resistance rate for E. faecalis strains that were 41% resistant to ciprofloxacin. Both types showed 100% sensitivity to linezolid.

CONCLUSIONS

The dissemination of antibiotic-resistant pathogens poses the need to implement surveillance programs and, consequently, to develop strategies to prevent the emergence of such pathogens in order to optimize patient outcomes.

The antibiotic strategies during percutaneous nephrolithotomy in China revealed the gap between the reality and the urological guidelines

Background

Correct perioperative antibiotic strategies are crucial to prevent postoperative infections during percutaneous nephrolithotomy (PCNL). We aimed to compare the realistic antibiotic strategies applied in China with current urological guidelines.

Methods

Between April and May 2020, urologists from China were invited to finish an online cross-sectional survey. The questionnaire was designed according to the current urological guidelines and literatures.

Results

3393 completed responses were received. 61.1% (2073/3393) respondents had urological experience of more than 10 years. 72.4% urologists chose multiple-dose antibiotics for patients with both negative urine culture (UC-) and negative urine microscopy (UM-) preoperatively. Respondents in central China (OR = 1.518; 95% CI 1.102–2.092; P = 0.011), east China (OR = 1.528; 95% CI 1.179–1.979; P = 0.001) and northeast China (OR = 1.904; 95% CI 1.298–2.792; P = 0.001) were more likely to prescribe multiple-dose antibiotic for UC-UM- patients. Notably, the respondents who finished PCNL exceeded 100 cases per year were in favor of single-dose administration (OR = 0.674; 95% CI 0.519–0.875; P = 0.003). There are only 8.3% urologists chose single-dose antibiotic for UC-UM+ patients, whereas 65.5% administered antibiotics for 1–3 days. Meanwhile, for UC+ patients, 59.0% of the urologists applied antibiotics shorter than 1 week, and only 26.3% of the urologists carried out routine re-examination of UC. Moreover, postoperative antibiotics were frequently prescribed for 3–6 days (1815; 53.5%). Finally, although 88.2% urologists considered stone culture important for management of postoperative antibiotics as the guideline recommended, only 18.5% performed it routinely.

Conclusions

The antibiotic strategies are different between current practice in China and the urological guidelines. The dissimilarities suggested that further studies should be conducted to investigate the reasons of the differences and standardize the application of antibiotics.

Investigation of Virulence Genes of the Predominant Bacteria Associated with Renal Stones and their Correlation with Postoperative Septic Complications

Purpose

Nephrolithiasis is a worldwide disease, and 4.7% of the patients may develop postoperative sepsis. Characterization of virulence genes of bacteria associated with renal stones is still lacking in the literature. The study aimed to investigate the virulence genes of the predominant stone bacterial isolate and their association with postoperative septic complications in patients treated with percutaneous nephrolithotomy (PCNL).

Methods

Stone and midstream urine samples were collected from 200 nephrolithiasis patients who underwent PCNL. Microbiological examination and virulence profile were studied for the common bacteria isolated from the stones.

Results

Microbiological analysis revealed that Staphylococcus aureus was the predominant organism in stone samples (42.8%), while Escherichia coli (56.6%) was the dominant pathogen in midstream urine. Eight patients (4%) developed septic complications; stone culture was positive for S. aureus in seven and E. coli in one patient, while all but one had negative midstream urine. The patient with positive midstream urine culture had also S. aureus infection. Detection of virulence genes in S. aureus isolated from stones showed a high positivity of the hemolysine gene hla (93.3%) and adhesion gene fnbA (73.3%), whereas enterotoxin genes (sec and sea) were negative in all S. aureus stone cultures. Moreover, the adhesion genes (fnbB and can), hemolysine gene (hlb), panton-valentine leukocidin (pvl) gene and the enterotoxin gene (seb) were significantly higher in septic patients compared to the non-septic ones (p< 0.05). Interestingly, there was a significant relation between the existence of virulence genes and the resistance of antibiotics (p < 0.05).

Conclusion

There has been a notable shift toward gram-positive organisms (S. aureus) in the stone culture. Moreover, S. aureus virulence genes were significantly attributed to the resistance of some antibiotics and postoperative septic complications, suggesting that the stone culture could be more informative than urine culture, especially in predicting the risk of postoperative sepsis.

Persistent Escherichia coli infection in renal tubular cells enhances calcium oxalate crystal-cell adhesion by inducing ezrin translocation to apical membranes via Rho/ROCK pathway

Recent evidence has suggested that recurrent urinary tract infection (UTI) can cause not only infection stones but also metabolic stones (e.g., those containing calcium oxalate monohydrate or COM). However, precise mechanisms underlying UTI-induced metabolic stones remained unknown. In this study, Escherichia coli, the most common bacterium found in recurrent UTI was used to establish the in vitro model for persistent infection of renal epithelial cells. The promoting effects of persistent E. coli infection on kidney stone formation were validated by COM crystal-cell adhesion assay, followed by immunofluorescence study for changes in surface expression of the known COM crystal receptors. Among the five receptors examined, only ezrin had significantly increased level on the surface of persistently infected cells without change in its total level. Such translocation of ezrin to apical membranes was confirmed by Western blotting of apical membrane and cytosolic fractions and confocal microscopic examination. Additionally, persistent infection increased phosphorylation (Thr567) of ezrin. However, all of these changes induced by persistent E. coli infection were significantly inhibited by small-interfering RNA (siRNA) specific for ezrin or a Rho-associated kinase (ROCK)-specific inhibitor (Y-27632). In summary, this study provides a piece of evidence demonstrating that persistent infection by E. coli, one of the non-urease-producing bacteria, may contribute to COM metabolic stone formation by translocation of ezrin to apical membranes, thereby promoting COM crystal-cell adhesion. Such ezrin translocation was mediated via Rho/ROCK signaling pathway. These findings may, at least in part, explain the pathogenic mechanisms underlying recurrent UTI-induced metabolic kidney stone disease.

Chemical Profiling and In Vitro Antiurolithiatic Activity of Pleurolobus gangeticus (L.) J. St.- Hil. ex H. Ohashi & K. Ohashi Along with Its Antioxidant and Antibacterial Properties

Pleurolobus gangeticus (L.) J. St.- Hil. ex H. Ohashi & K. Ohashi (Fabaceae) is an important medicinal plant used to treat various ailments. In this study, we report the antiurolithiatic, antioxidant, and antibacterial potential of chloroform fraction (CF) from P. gangeticus roots. For the chemical profiling, HPTLC, FT-IR, and GC-MS techniques of the CF were carried out, and phytochemical investigation was revealed that stigmasterol (45.06%) is one of the major components present in the fraction. The nucleation and aggregation assays were used to evaluate the in vitro antiurolithiatic activity at various concentration (2-10 mg/mL) of the CF. The results showed that the chloroform fraction had dose-dependent effects on Calcium Oxalate (CaOx) crystal formation. In both the assays, the maximum concentration of 10 mg/mL has shown better results. This concentration resulted significant increase in CaOx crystal nucleation along with the reduction of crystal size and the inhibition of crystal aggregation. Further, the CF showed stronger antioxidant (DPPH, NO, SOD, TRC) potential with an IC₅₀ values of 415.9327, 391.729, 275.971, and 419.14 µg/mL, respectively. The antibacterial evaluation displayed effective results in the Agar well diffusion assay against selective urinary tract infection (UTI) pathogens (Escherichia coli, Klebsiella pneumonia, and Staphylococcus aureus). A maximum zone of inhibition (ZOI) 12.33 ± 1.05 mm for K pneumonia and minimum ZOI of 8.46 ± 0.27 mm for S. aureus were obtained. Further, the ADME-PK property of the stigmasterol was investigated, and it was found to pass the Lipinski and Ghose rules, supporting the drug-likeliness. This is the first record of the antiurolithiatic potential of P. gangeticus along with antioxidant and antibacterial activities. These findings give an insight into the effective drug development and treatment for kidney stones in future.

Using machine learning techniques to predict antimicrobial resistance in stone disease patients

PURPOSE

Artificial intelligence is part of our daily life and machine learning techniques offer possibilities unknown until now in medicine. This study aims to offer an evaluation of the performance of machine learning (ML) techniques, for predicting bacterial resistance in a urology department.

METHODS

Data were retrieved from laboratory information system (LIS) concerning 239 patients with urolithiasis hospitalized in the urology department of a tertiary hospital over a 1-year period (2019): age, gender, Gram stain (positive, negative), bacterial species, sample type, antibiotics and antimicrobial susceptibility. In our experiments, we compared several classifiers following a tenfold cross-validation approach on 2 different versions of our dataset; the first contained only information of Gram stain, while the second had knowledge of bacterial species.

RESULTS

The best results in the balanced dataset containing Gram stain, achieve a weighted average receiver operator curve (ROC) area of 0.768 and F-measure of 0.708, using a multinomial logistic regression model with a ridge estimator. The corresponding results of the balanced dataset, that contained bacterial species, achieve a weighted average ROC area of 0.874 and F-measure of 0.783, with a bagging classifier.

CONCLUSIONS

Artificial intelligence technology can be used for making predictions on antibiotic resistance patterns when knowing Gram staining with an accuracy of 77% and nearly 87% when identifying specific microorganisms. This knowledge can aid urologists prescribing the appropriate antibiotic 24-48 h before test results are known.

Comparative study of the bacterial distribution and antimicrobial susceptibility of uropathogens in older and younger patients with urinary stones

Background

This study compared the bacterial spectrum and antibiotic susceptibility of uropathogens in older and younger patients with urinary stones to provide appropriate antibiotic management.

Methods

We retrospectively reviewed urinary tract infection patients with urolithiasis, presented to Xiangya Hospital from March 2014 to April 2021. Patients were divided into older and younger groups according to 60 years of age. The bacterial spectrum and drug sensitivity of uropathogens were compared.

Results

A total of 542 strains of uropathogens (177 in older and 365 in younger groups) were isolated from 507 patients. E. coli (41.8% vs 43.6%) remains the most common pathogen, followed by E. faecalis (6.2% vs 9.6%) in older and younger groups, respectively. Particularly, K. pneumoniae was significantly more frequent in older (9.6%) than in younger group (4.7%, P < .05). E. faecium was substantially more prevalent in older group (6.2%) than in younger group (2.7%, P < .05). The proportion of males increased in older patients (47.3%) than in younger patients (34.9%, P = 0.007). In both groups, major Gram-negative bacteria (E. coli and K. pneumoniae) revealed a high sensitivity over 70% to piperacillin/tazobactam, imipenem and amikacin, whereas the resistance level was high to penicillin, tetracycline and vancomycin. Major Gram-positive (E. faecalis and E. faecium) isolates demonstrated high sensitivity of over 50% to gentamicin and vancomycin in both groups. Furthermore, uropathogens isolated from younger urolithiasis patients were more susceptible to antimicrobials than those isolated from older patients.

Conclusions

The male increased in the older urolithiasis patients with UTI and uropathogens microbial spectrum in older urolithiasis patients are different from younger. High susceptibility and age should be utilized in empirical antibiotic selection to avoid increased multidrug-resistant bacteria.

Dissecting and Evaluating the Therapeutic Targets of Coptis Chinensis Franch in the Treatment of Urinary Tract Infections Induced by Escherichia coli

Coptis chinensis Franch (CCF) is extensively used in the treatment of inflammatory-related diseases. Accumulating studies have previously demonstrated the anti-inflammatory properties of CCF, yet data on its exact targets against urinary tract infections (UTIs) remain largely unknown. Therefore, the present study decodes the potential targets of action of CCF against UTIs by network pharmacology combined with experiment evaluations. Based on the pharmacology network analysis, the current study yielded six core ingredients: quercetin, palmatine (R)-canadine, berlambine, berberine, and berberrubine. The protein–protein interaction network (PPI) was generated by the string database, and then, four targets (IL6, FOS, MYC, and EGFR) were perceived as the major CCF targets using the CytoNCA plug-in. The results of molecular docking showed that the six core constituents of CCF had strong binding affinities toward the four key targets of UTIs after docking into the crystal structure. The enrichment analysis indicated that the possible regulatory mechanisms of CCF against UTIs were based on the modules of inflammation, immune responses, and apoptosis among others. Experimentally, the Escherichia coli (E. coli) strain CFT073 was applied to establish in vivo and in vitro models. In vivo results revealed that the key targets, IL6 and FOS, are significantly upregulated in rat bladder tissues of UTIs, whereas the expression of MYC and EGFR remained steady. Last, in vitro results further confirmed the therapeutic potential of CCF by reducing the expression of IL6 and FOS. In conclusion, IL6 and FOS were generally upregulated in the progression of E. coli–induced UTIs, whereas the CCF intervention exerted a preventive role in host cells stimulated by E. coli, partially due to inhibiting the expression of IL6 and FOS.

Antibiotic Sensitivity of Proteus mirabilis Urinary Tract Infection in Patients with Urinary Calculi

BACKGROUND

The study's objective was to determine Proteus mirabilis susceptibility in individuals with urinary tract infections and stones to antibiotics and prescribe optimal antimicrobial treatment.

METHODS

Nonrepetitive Proteus mirabilis strains were isolated from urine specimens obtained from 317 patients diagnosed with urinary stones from January, 2018, to December, 2021. A VITEK mass spectrometer was used for species identification, and a VITEK-compact 2 automatic microbial system was used for the antimicrobial susceptibility test (AST). Susceptibility to imipenem and cefoperazone/sodium sulbactam was tested by the disc diffusion method (K-B method). The antibiotic sensitivity of the strains was analyzed by sex and season.

RESULTS

A total of 317 patients were reviewed: 202 females (63.7%) and 115 males (36.3%). Proteus mirabilis infections were observed during spring (21.8%, n = 69), summer (26.2%, n = 83), autumn (33.8%, n = 107), and winter (18.2%, n = 57). Proteus mirabilis infections in females were diagnosed most often during the fall (24.3%, n = 77) and during the summer in males (11.0%, n = 35) (p = 0.010). Female patients responded best to levofloxacin (p = 0.014), and male patients responded best to sulfamethoxazole (p = 0.023). Seasonal variation in antibiotic sensitivity was confirmed, with significantly higher rates in the winter for cefuroxime (p = 0.002) and sulfamethoxazole (p = 0.002). Significant seasonal increases were also found in levofloxacin sensitivity during the summer (p = 0.005).

CONCLUSIONS

Highly effective antibiotics such as cefoxitin and ceftazidime should be used empirically by considering antibiotic sensitivity changes by sex, season, and year. Regional studies should be conducted frequently.

Multiple drug resistance bacterial isolates and associated factors among urinary stone patients at the University of Gondar Comprehensive Specialized Hospital, Northwest Ethiopia

BACKGROUND

The urinary stone and urinary tract infection (UTI) are invariably associated and are frequent causes of morbidity. Date on burden of UTI among urinary stone patients is lacking in Ethiopia. This study was aimed to assess bacterial profile, antimicrobial susceptibility and associated factors among urinary stone patients at the University of Gondar Comprehensive Specialized Hospital.

METHODS

An institution based cross sectional study was conducted. Basic sociodemographic data were collected using a structured questionnaire. Bacterial identification of uropathogens and drug susceptibility testing were done following standard microbiological techniques. The data were entered and analyzed using SPSS version-23. Bivariate and multivariate logistic regressions were used to identify possible associated risk factors. Results with P value < 0.05 was considered statistically significant.

RESULT

A total of 300 urinary stone patients were enrolled. Of these, 153 (51%) were male and 261(87%) were urban residents. The overall prevalence of urinary tract infection was 49 (16.3%) (95% CI 12-21%). A high level of resistance was observed to ampicillin, penicillin and trimethoprim-sulfamethoxazole while majority of isolates were most sensitive to nitrofurantoin and ciprofloxacin. Multi-drug resistant isolates were 16/49 (32.7%), 75% of them being Enterobacteriaceae isolates. More than one-third 9/26 (34.6%) of Gram-negative isolates were Extended Spectrum Beta-Lactamase (ESBL) producing E. coli and K. pneumoniae. Being female, history of urinary tract infection and history of drug use were the independent risk factors.

CONCLUSION

Most of the bacterial isolates from urinary stone patients were resistant to ampicillin, penicillin and trimethoprim-sulfamethoxazole. E. coli and K. pneumoniae were the most common extended spectrum beta-lactamase producing isolates. Sex, history of urinary tract infection and previous drug use were found to be risk factors. Routine diagnosis of urinary stone patients for urinary tract infection should be promoted and further researches are encouraged.

The characteristic and relationship of Escherichia coli isolated from urine and stones in patients with calcium oxalate stones

Previous clinical studies have shown that Escherichia coli (E. coli) predominated in urine and stone culture from calcium oxalate (CaOx) stone disease. The characteristic and relationship between E. coli isolated from urine cultures (EUC) and stone cultures (ESC) are compared. 83 E. coli (33 EUC and 50 ESC, respectively) from 66 CaOx stone patients were recruited in the study. E. coli in urine and stones from those patients were assessed by antimicrobial susceptibility test, genotyping and phylogenetic grouping. Furthermore, whole genome sequencing and comparative genomic analysis in paired ESC and EUC isolated strains from eight patients were carried out. The E. coli strains from ESC and EUC were not only multidrug resistant (MDR), but also had the similar pattern of resistant genes. The dominant phylogenetic group was B2, which was found in 54.0% of the ESC samples and 69.7% of the EUC samples, respectively. The virulence genes of E. coli, which isolated from stones and urine in the same patients, were highly homologous and largely consistent. Meanwhile, these E. coli strains were located in the same clade originated from a common ancestor. ESC and EUC isolated from patients with CaOx stones had a high prevalence of phylogenetic groups B2. Bacterial strains isolated from urine and stones in the same patient had consistent antimicrobial susceptibility profiles, genotyping, phylogenetic groups, virulence and resistance genes, also with high sequence co-linearity and close relationships.

Dysbiosis of urine microbiota in obstructive urinary retention patients revealed by next-generation sequencing

BACKGROUND

Urinary retention (UR) is a common urinary system disease can be caused by urinary tract obstruction with numerous reasons, however, the role of urine microbes in these disorders is still poorly understood. The aim of this study was to identify the urine microbial features of two common types of obstructive UR, caused by urinary stones or urinary tract tumors, with comparison to healthy controls.

METHODS

Urine samples were collected from a cohort of 32 individuals with stone UR, 25 subjects with tumor UR and 25 healthy controls. The urine microbiome of all samples was analyzed using high-throughput 16S rRNA (16S ribosomal RNA) gene sequencing.

RESULTS

We observed dramatically increased urine microbial richness and diversity in both obstructive UR groups compared to healthy controls. Despite different origins of UR, bacteria such as Pseudomonas, Acinetobacter and Sphingomonas were enriched, while Lactobacillus, Streptococcus, Gardnerella, Prevotella and Atopobium were decreased in both UR groups in comparison with healthy controls, exhibited an approximate urine microbial community and functional characteristics of two types of obstructive UR. Furthermore, disease classifiers were constructed using specific enriched genera in UR, which can distinguish stone UR or tumor UR patients from healthy controls with an accuracy of 92.29% and 97.96%, respectively.

CONCLUSION

We presented comprehensive microbial landscapes of two common types of obstructive urinary retention and demonstrated that urine microbial features of these patients are significantly different from that of healthy people. The urine microbial signatures would shed light on the pathogenesis of these types of urinary retention and might be used as potential classification tools in the future.

Bacterial spectrum and antibiotic resistance of urinary tract infections in patients treated for upper urinary tract calculi: a multicenter analysis

The purpose of this study is to collect information on the bacterial resistance to antibiotics of bacteria isolated from urine cultures of patients treated for upper urinary tract calculi. Data of patients with urinary tract infection and urolithiasis were retrospectively reviewed to collect information on age, gender, stone size, location, hydronephrosis, procedure of stone removal and antibiotic treatment, identification and susceptibility of pathogens, symptoms, and infectious complications. A total of 912 patients from 11 centers in 7 countries (Bulgaria, Greece, Italy, North Macedonia, Spain, and Turkey) were studied. Mean age was 54 ± 16 years and M/F ratio 322/590. Out of 946 microbial isolates, the most common were E. coli, Gram-positive, KES group (Klebsiella, Enterobacter, Serratia), Proteus spp., and P. aeruginosa. Carbapenems, piperacillin/tazobactam and amikacin showed low resistance rates to E. coli (2.5%, 7%, and 3.6%) and Proteus spp. (7.7%, 16%, and 7.4%), but higher rates were observed with Klebsiella spp., P. aeruginosa, and Gram-positive. Fosfomycin had resistance rates less than 10% to E. coli, 23% to KES group, and 19% to Gram-positive. Amoxicillin/clavulanate, cephalosporins, quinolones, and TMP/SMX showed high resistance rates to most bacterial strains. High rates of antibiotic resistance were observed in patients candidate to stone treatment from South-Eastern Europe. The empirical use of antibiotics with low resistance rates should be reserved to the most serious cases to avoid the increase of multidrug resistant bacteria. Basing on our results, carbapenems, piperacillin/tazobactam, and amikacin may be a possible option for empiric treatment of urinary stone patients showing systemic symptoms.

An evaluation of multidrug-resistant (MDR) bacteria in patients with urinary stone disease: data from a high-volume stone management center

PURPOSE

To investigate the prevalence of MDR bacteria in patients with urinary stones and the risk factors for its formation.

METHODS

A retrospective study was performed among patients with urinary stones in Beijing Tsinghua Changgung Hospital from December 2014 to May 2018. Patients with positive urinary cultures and drug sensitivity results were included. MDR were defined as any bacteria that have resistance to at least one agent in at least three classes of antibiotics. Bacteria distribution and resistance patterns were calculated.

RESULTS

1655 patients with urinary stones were eligible for analysis, among which 367 patients had positive urinary culture, yielding 457 isolates of 45 species. Escherichia coli remained the most common organism with a prevalence of 29.3%, followed by Enterococcus faecalis (12.0%), Proteus mirabilis (10.5%), and Klebsiella pneumonia (6.8%). 44.4% isolates were identified as MDR. The three most common Gram-negative bacteria were Escherichia coli, Proteus mirabilis, and Klebsiella pneumoniae, with a MDR rate of 84.33%, 62.5%, and 48.39%, respectively. Drug-resistant rates were different between MDR and non-MDR in ampicillin, cefazolin, ceftriaxone, cefepime, gentamicin, amikacin, and levofloxacin (all with p value < 0.05). In multivariate analysis, indwelling catheters (OR 3.1, 95% CI 1.07-8.98) and antibiotics use in the last 3 months (OR 2.14, 95% CI 1.04-4.38) were significantly associated with MDR formation.

CONCLUSIONS

MDR bacteria were common among patients with urinary stones in our center and achieved high drug-resistant rates in ampicillin, first-generation and part of third-generation cephalosporins, and fluoroquinolones. Indwelling catheters and antibiotics used in the last 3 months were independent risk factors for MDR formation. Tailored antibacterial strategies still should be established according to the local bacterial spectrum and patient condition.

Comparison of Escherichia coli and Klebsiella pneumoniae Acute Pyelonephritis in Korean Patients

Background

Escherichia coli and Klebsiella pneumoniae are two of the most common causes of urinary tract infection. The purpose of this study was to compare clinical characteristics and antimicrobial susceptibility of acute pyelonephritis (APN) between E. coli and K. pneumoniae.

Materials and Methods

We retrospectively reviewed medical records of patients with APN due to E. coli and K. pneumoniae between February 2014 and October 2017.

Results

A total 329 patients were enrolled; 258 cases of E. coli and 71 cases of K. pneumoniae. Among them, 219 cases were categorized into community-onset APN; 194 cases of E. coli and 25 cases of K. pneumoniae, and 110 patients were categorized into healthcare-associated APN; 64 cases of E. coli and 46 cases of K. pneumoniae. Catheter-associated APN was more frequently observed in K. pneumoniae in both community-onset and healthcare-associated APN. Neurogenic bladder, obstructive uropathy, urinary tract stone, bacteremia, and severe APN were more related to E. coli in healthcare-associated APN. In multivariate analysis, urinary catheter was more associated with K. pneumoniae (odds ratio [OR] 9.643, 95% confidence intervals [CI] 4.919-18.904, P = 0.001) and neurogenic bladder was more associated with E. coli (OR 3.765, 95% CI 1.112-12.772, P = 0.033). Extended-spectrum β-lactamase (ESBL) production was observed in 29.0% of E. coli in community-onset APN. Among ESBL, antimicrobial susceptibility of piperacillin/tazobactam was significantly higher in E. coli and ciprofloxacin was significantly higher in K. pneumoniae.

Conclusion

K. pneumoniae were more associated with urinary catheter while E. coli tended to be more associated with urogenital problems. ESBL positivity showed no significance in healthcare-associated APN. In community-onset APN, ESBL producing E. coli was more observed than K. pneumoniae.

Identification of small molecule compounds active against Staphylococcus aureus and Proteus mirabilis

Staphylococcus aureus is a human pathogen rapidly becoming a serious health problem due to ease of acquiring antibiotic resistance. To help identify potential new drug candidates effective against the pathogen, a small focused library was screened for inhibition of bacterial growth against several pathogens, including S. aureus. At least one of the compounds, Compound 10, was capable of blocking bacterial growth of S. aureus in a test tube with IC₅₀ = 140 ± 30 μM. Another inhibitor, Compound 7, was bacteriostatic against S. aureus with IC₅₀ ranging from 33 to 150 μM against 3 different strains. However, only Compound 7 was bactericidal against P. mirabilis as examined by electron microscopy. Human cell line toxicity studies suggested that both compounds had small effect on cell growth at 100 μM concentration as examined by MTT assay. Analysis of compounds' structures showed lack of similarity to any known antibiotics and bacteriostatics, potentially offering the inhibitors as an alternative to existing solutions in controlling bacterial infections for selected pathogens.