One-step Synthesis of Silver Nanoparticles Using Saudi Arabian Desert Seasonal Plant Sisymbrium irio and Antibacterial Activity Against Multidrug-Resistant Bacterial Strains

Globally, antimicrobial resistance has grown at an alarming rate. To combat the multidrug-resistant (MDR) superbugs, silver nanoparticles (Ag NPs) were synthesized using an aqueous leaf extract of seasonal desert plant Sisymbrium irio obtained from the central region of Saudi Arabia by a simple one-step procedure. The physical and chemical properties of the Ag NPs were investigated through ultraviolet visisble analysis (UV-vis), Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscope (SEM), and transmission electron microscope (TEM) analysis. The UV-vis spectrum showed an absorption band at 426 nm. The XRD results showed a highly crystalline face-centered cubic structure. The surface morphology analyzed using SEM and TEM analyses showed the particle size to be in the range 24 nm to 50 nm. Various concentrations of Ag NPs were tested against MDR Pseudomonas aeruginosa and Acinetobacter baumanii that cause ventilator-associated pneumonia (VAP). American Type Culture Collection (ATCC) Escherichia coli-25922 was used as the reference control strain. The Ag NPs effectively inhibited tested pathogens, even at the lowest concentration (6.25 µg) used. The bacterial inhibitory zone ranged from 11–21 mm. In conclusion, the newly synthesized Ag NPs could be a potential alternative candidate in biomedical applications in controlling the spread of MDR pathogens.

Prevalence and risk factors for trimethoprim-sulfamethoxazole-resistant Escherichia coli among women with acute uncomplicated urinary tract infection in a developing country

BACKGROUND

Prospective studies from developing countries that have investigated risk factors for trimethoprim-sulfamethoxazole (TMP-SMX)-resistant Escherichia coli in women with uncomplicated urinary tract infection (UTI) remain scarce.

METHODS

Women with acute uncomplicated UTI were enrolled prospectively. Urine was sent for antimicrobial susceptibility testing. Logistic regression analysis was used to identify risk factors for TMP-SMX resistance.

RESULTS

Of 405 participants, 229 (56.5%) had bacteriuria (mean age 31.9 ± 9.5 years). In the previous 12 months, 77 (33.6%) had experienced at least one UTI episode and 106 (46.3%) reported antimicrobial use. The most common uropathogens were E. coli (75.8%) and Staphylococcus saprophyticus (8.9%). For the 179 E. coli, resistance rates were highest for ampicillin (64.3%) and TMP-SMX (41.3%). Resistance to cephalosporins, nitrofurantoin, and fluoroquinolones was much lower compared with the hospital laboratory-based surveillance data. Risk factors for TMP-SMX resistance were UTI in the last 6 months (odds ratio 2.22; p = 0.04) and the number of UTI episodes in the past year (odds ratio 2.06; p = 0.004). The number of UTI episodes (adjusted odds ratio 2.21; p = 0.02) remained significant on multivariate analysis.

CONCLUSIONS

TMP-SMX resistance was high. Number of previous UTI episodes was associated with increased risk of resistance; prior antimicrobial use was not. Hospital antibiograms should be used with caution when treating uncomplicated UTI.

Prevalence and antibiotic resistance pattern of urinary tract bacterial infections in Dessie area, North-East Ethiopia

BACKGROUND

Different studies have indicated that urinary tract infections frequently occur in both community and hospital environments and are of the most common bacterial infections in humans. the outcomes of urinary tract infections are increased hospitalization, increased direct patient costs and mortality. In Dessie, the prevalence of the commmon pathogens and antibiotic susceptibility pattern is not well studied sofar. Thus, the aim of this study is to address these gaps in the study area.

METHODS

Retrospective study was conducted in Dessie regional health reseacrh laboratory from January 1-March 31, 2012. All culture and antibiotic susceptibility test results of patients' diagnosed with UTI from September 2002 to September 2011 G.C were included in the study. Data were abstracted using structured questionnaires and finally, entered into SPSS Windows version 16.0, and descriptive statistics was generated to meet the study objective.

RESULTS

During the last ten years 680 (27.35%) bacteria were isolated in the regional laboratory. The most commonly isolated were E. coli 410 (60.29%), Pseudomonas species 59 (8.68%), Proteus species 53 (7.79%), S. aurous 50 (7.35%) and Klebsiella species 40 (5.88%). The E.coli were susceptible to Nitrofurantoin 43 (89.6%), furantoin 124 (87.3%), Nalidixic acid 91 (86.7%), kanamycin 116 (80%) & ciprofloxacin 66 (71.7%) but were almost resistant to Ampicillin, tetracycline, & trimethoprim-sulfamethoxazole. Similarly Pseudomonas and proteus species were resistant to almost all antibiotics except Gentamycin.

CONCLUSION

The E.coli, pseudomonas and proteus species were the commonly isolated bacteria in the regional health research laboratory. A majority of isolated bacterial microbes were resistant to antibiotics commonly used in clinical practices and generally available in the local economy without prescription. Culture results are necessary before initiating antibiotics.

Resistance patterns of nosocomial urinary tract infections in urology departments: 8-year results of the global prevalence of infections in urology study

OBJECTIVE

To present the worldwide antibiotic resistance rates of uropathogens reported in nosocomial urinary tract infections (NAUTI) during the period of 2003-2010.

MATERIALS AND METHODS

Data from the Global Prevalence Study of Infections in Urology from the period of 2003-2010 were analyzed to evaluate the resistance rates of pathogens causing NAUTI. The web-based application was used to record data of investigators from urology departments participating in the study every year during the days allocated in November. Each center was allowed to enter data on a single day of the study. The point prevalence data was used to find differences among geographic regions and years by utilizing multiple logistic regression analysis.

RESULTS

A total of 19,756 patients were hospitalized during the study period, and in 1,866 of them, NAUTI was reported. Proof of infection was reported in 1,395 patients. Resistance rates of all antibiotics tested other than imipenem against the total bacterial spectrum were higher than 10 % in all regions. Resistance to almost all pathogens was lowest in North Europe, and there is no single year where an outbreak of resistance has been detected.

CONCLUSION

The resistance rates of most of the uropathogens against the antibiotics tested did not show significant trends of increase or decrease with Asia exhibiting the highest rates in general. The only antibiotic tested with an overall resistance rate below 10 % was imipenem. Knowledge of regional and local resistance data and prudent use of antibiotics are necessary to optimize antibiotic therapy in urological patients with NAUTI.

Synchrotron X-ray fluorescence microscopy of gallium in bladder tissue following gallium maltolate administration during urinary tract infection

A mouse model of cystitis caused by uropathogenic Escherichia coli was used to study the distribution of gallium in bladder tissue following oral administration of gallium maltolate during urinary tract infection. The median concentration of gallium in homogenized bladder tissue from infected mice was 1.93 μg/g after daily administration of gallium maltolate for 5 days. Synchrotron X-ray fluorescence imaging and X-ray absorption spectroscopy of bladder sections confirmed that gallium arrived at the transitional epithelium, a potential site of uropathogenic E. coli infection. Gallium and iron were similarly but not identically distributed in the tissues, suggesting that at least some distribution mechanisms are not common between the two elements. The results of this study indicate that gallium maltolate may be a suitable candidate for further development as a novel antimicrobial therapy for urinary tract infections caused by uropathogenic E. coli.

Antimicrobial resistance surveillance systems: Are potential biases taken into account?

BACKGROUND

The validity of surveillance systems has rarely been a topic of investigation.

OBJECTIVE

To assess potential biases that may influence the validity of contemporary antimicrobial-resistant (AMR) pathogen surveillance systems.

METHODS

In 2008, reports of laboratory-based AMR surveillance systems were identified by searching Medline. Surveillance systems were appraised for six different types of bias. Scores were assigned as '2' (good), '1' (fair) and '0' (poor) for each bias.

RESULTS

A total of 22 surveillance systems were included. All studies used appropriate denominator data and case definitions (score of 2). Most (n=18) studies adequately protected against case ascertainment bias (score = 2), with three studies and one study scoring 1 and 0, respectively. Only four studies were deemed to be free of significant sampling bias (score = 2), with 17 studies classified as fair, and one as poor. Eight studies had explicitly removed duplicates (score = 2). Seven studies removed duplicates, but lacked adequate definitions (score = 1). Seven studies did not report duplicate removal (score = 0). Eighteen of the studies were considered to have good laboratory methodology, three had some concerns (score = 1), and one was considered to be poor (score = 0).

CONCLUSION

Contemporary AMR surveillance systems commonly have methodological limitations with respect to sampling and multiple counting and, to a lesser degree, case ascertainment and laboratory practices. The potential for bias should be considered in the interpretation of surveillance data.

Antimicrobial resistance and spread of multi drug resistant Escherichia coli isolates collected from nine urology services in the Euregion Meuse-Rhine

We determined the prevalence and spread of antibiotic resistance and the characteristics of ESBL producing and/or multi drug resistant (MDR) Escherichia coli isolates collected from urine samples from urology services in the Euregio Meuse-Rhine, the border region of the Netherlands (n = 176), Belgium (n = 126) and Germay (n = 119). Significant differences in resistance between the three regions were observed. Amoxicillin-clavulanic acid resistance ranged from 24% in the Netherlands to 39% in Belgium (p = 0.018), from 20% to 40% (p<0.004) for the fluoroquinolones and from 20% to 40% (p = 0.018) for the folate antagonists. Resistance to nitrofurantoin was less than 5%. The prevalence of ESBL producing isolates varied from 2% among the Dutch isolates to 8% among the German ones (p = 0.012) and were mainly CTX-M 15. The prevalence of MDR isolates among the Dutch, German and Belgian isolates was 11%, 17% and 27%, respectively (p< = 0.001 for the Belgian compared with the Dutch isolates). The majority of the MDR and ESBL producing isolates belonged to ST131. This study indicates that most antibiotics used as first choice oral empiric treatment for UTIs (amoxicillin-clavulanic acid, fluoroquinolones and folate antagonists) are not appropriate for this purpose and that MDR strains such as CTX-M producing ST131 have spread in the entire Euregion. Our data stress the importance of ward specific surveillance to optimize empiric treatment. Also, prudent use of antibiotics and further research to alternative agents are warranted.

Risk factors for fluoroquinolone-resistant Escherichia coli in adults with community-onset febrile urinary tract infection

OBJECTIVES

To assess risk factors for fluoroquinolone resistance in community-onset febrile Escherichia coli urinary tract infection (UTI).

METHODS

A nested case-control study within a cohort of consecutive adults with febrile UTI presenting at primary healthcare centres or emergency departments during January 2004 through December 2009. Resistance was defined using EUCAST criteria (ciprofloxacin MIC >1.0 mg/L). Cases were subjects with fluoroquinolone-resistant E. coli, and controls those with fluoroquinolone-susceptible isolates. Multivariable logistic regression analysis was used to identify potential risk factors for fluoroquinolone resistance.

RESULTS

Of 787 consecutive patients, 420 had E. coli-positive urine cultures. Of these, 51 (12%) were fluoroquinolone resistant. Independent risk factors for fluoroquinolone resistance were urinary catheter [odds ratio (OR) 3.1; 95% confidence interval (CI) 0.9-11.6], recent hospitalization (OR 2.0; 95% CI 1.0-4.3) and fluoroquinolone use in the past 6 months (OR 17.5; 95% CI 6.0-50.7). Environmental factors (e.g. contact with animals or hospitalized household members) were not associated with fluoroquinolone resistance. Of fluoroquinolone-resistant strains, 33% were resistant to amoxicillin/clavulanate and 65% to trimethoprim/sulfamethoxazole; 14% were extended-spectrum β-lactamase (ESBL) positive compared with <1% of fluoroquinolone-susceptible isolates.

CONCLUSIONS

Recent hospitalization, urinary catheter and fluoroquinolone use in the past 6 months were independent risk factors for fluoroquinolone resistance in community-onset febrile E. coli UTI. Contact with animals or hospitalized household members was not associated with fluoroquinolone resistance. Fluoroquinolone resistance may be a marker of broader resistance, including ESBL positivity.

Correlation of overexpression of efflux pump genes with antibiotic resistance in Escherichia coli Strains clinically isolated from urinary tract infection patients

Escherichia coli is one of the most common pathogens in urinary tract infections (UTIs), and antibiotic resistance in E. coli is becoming a serious problem in treating UTI. Efflux system overexpression is reported to contribute to E. coli resistance to several antibiotics. This study investigated the correlation of antibiotic susceptibilities with the overexpression of the efflux pump genes such as marA, yhiU, yhiV, and mdfA and with risk factors for antibiotic resistance in E. coli isolated from UTI patients. We examined the expression level of efflux pump genes using quantitative real-time reverse transcription-PCR (qRT-PCR). We also tested the in vitro susceptibilities to 12 kinds of antibiotics in 64 clinical strains of E. coli isolated from UTI patients. By multivariate analyses we revealed significant relationships between the overexpression of (i) marA and MICs of cefepime (FEP) and nalidixic acid (NAL), (ii) yhiV and MICs of minocycline (MIN), and (iii) mdfA and MICs of sitafloxacin (STX). In our investigation of the efflux pump genes, risk factors such as gender and the previous use of fluoroquinolones correlated with the overexpression of marA, and indwelling catheter use correlated with the overexpression of mdfA. In conclusion, we demonstrated that the increased expression of efflux pump genes such as marA and mdfA can lead to fluoroquinolone resistance in E. coli. These results contribute to our knowledge of the efflux system and raise the possibility of developing new agents, such as efflux pump inhibitors (EPIs), to antibiotic-resistant E. coli.

Secular trend and risk factors for antimicrobial resistance in Escherichia coli isolates in Switzerland 1997-2007

BACKGROUND

Antibacterial resistance in Escherichia coli isolates of urinary infections, mainly to fluoroquinolones, is emerging. The aim of our study was to identify the secular trend of resistant E. coli isolates and to characterize the population at risk for colonization or infections with these organisms.

PATIENTS AND METHODS

Retrospective analysis of 3,430 E.coli first isolates of urine specimens from patients admitted to the University Hospital Basel in 1997, 2000, 2003, and 2007.

RESULTS

Resistance to ciprofloxacin, trimethoprim/sulfamethoxazole, and amoxicillin/clavulanate has increased over the 10-year study period (from 1.8% to 15.9%, 17.4% to 21.3%, and 9.5% to 14.5%, respectively). A detailed analysis of the 2007 data revealed that independent risk factors for ciprofloxacin resistance were age (5.3% < 35 years of age to 21.9% in patients > 75 years; odds ratio [OR] 1.29 per 10 years, 95% confidence interval [CI] 1.15-1.45, p < 0.001) and male gender (OR 1.59, 95% CI 1.05-2.41, p = 0.04). In contrast, nosocomial E. coli isolates were associated with lower odds of ciprofloxacin resistance (OR 0.51, 95% CI 0.28-0.67, p < 0.001). The frequency of resistant isolate rates was not influenced by the clinical significance (i.e., colonization vs urinary tract infection, UTI) or by whether the urine was taken from a urinary catheter. Importantly, the increase in ciprofloxacin resistance paralleled the increase in ciprofloxacin consumption in Switzerland (Pearson's correlation test R(2)= 0.998, p = 0.002). Of note, resistance was less frequent in isolates sent in by general practitioners. However, after adjustment for age and gender, only resistance against amoxicillin/clavulanate was found to be less frequent (OR 0.34, 95% CI 0.16-0.92, p = 0.03).

CONCLUSION

Our study reveals that resistance rates have been increasing during the last decade. Published resistance rates may lack information due to important differences regarding age, gender, and probable origin of the isolates. Empirical therapy for UTI should be guided more on individual risk profile and local resistance data than on resistance data banks.