Complicated catheter-associated urinary tract infections due to Escherichia coli and Proteus mirabilis

Antibiotic-decorated titanium with enhanced antibacterial activity through adhesive polydopamine for dental/bone implant

Implant-associated infections, which are normally induced by microbial adhesion and subsequent biofilm formation, are a major cause of morbidity and mortality. Therefore, practical approaches to prevent implant-associated infections are in great demand. Inspired by adhesive proteins in mussels, here we have developed a novel antibiotic-decorated titanium (Ti) material with enhanced antibacterial activity. In this study, Ti substrate was coated by one-step pH-induced polymerization of dopamine followed by immobilization of the antibiotic cefotaxime sodium (CS) onto the polydopamine-coated Ti through catechol chemistry. Contact angle measurement and X-ray photoelectron spectroscopy confirmed the presence of CS grafted on the Ti surface. Our results demonstrated that the antibiotic-grafted Ti substrate showed good biocompatibility and well-behaved haemocompatibility. In addition, the antibiotic-grafted Ti could effectively prevent adhesion and proliferation of Escherichia coli (Gram-negative) and Streptococcus mutans (Gram-positive). Moreover, the inhibition of biofilm formation on the antibiotic-decorated Ti indicated that the grafted CS could maintain its long-term antibacterial activity. This modified Ti substrate with enhanced antibacterial activity holds great potential as implant material for applications in dental and bone graft substitutes.

A high throughput, minimally invasive, ultrasound guided model for the study of catheter associated urinary tract infections and device encrustation in mice

PURPOSE

Catheter associated urinary tract infections are one of the most common health care associated infections. The condition is frequently complicated by encrustation, which blocks the catheter lumen. Preclinical research is limited by the lack of relevant high throughput and cost-effective animal models. Current models are restricted to female mice, associated with major transurethral loss of catheter materials during micturition, highly invasive and complex. We present an ultrasound guided, minimally invasive model that enables catheter associated urinary tract infection and catheter encrustation studies in each mouse gender.

MATERIALS AND METHODS

Catheter segments (4 mm) were implanted in murine bladders percutaneously in 15 males and 5 females, and transurethrally in 15 females using the Seldinger technique under ultrasound guidance. Proteus mirabilis was instilled intraluminally. Catheter encrustation was monitored by ultrasound. Bacteria were quantified in urine, and catheters and encrustation were analyzed on day 6 or 21.

RESULTS

Percutaneous and transurethral catheter implantations were performed in a mean ± SE 3.6 ± 0.8 vs 2.5 ± 0.5 minutes in all mice. Ultrasound confirmed that 100% and 66% of implanted catheters, respectively, remained indwelling during the study period. Catheter encrustation developed in P. mirabilis infected urine 48 hours after instillation and an increase with time was detected by ultrasound. Fourier transform spectroscopy of the encrustation confirmed a typical struvite spectrum. Control catheters remained sterile during 21 days.

CONCLUSIONS

Our minimally invasive, reproducible percutaneous technique is suitable for studying catheter associated urinary tract infection in each gender. Infecting urine with P. mirabilis generates a preclinical model of catheter encrustation within 3 days. The progression of encrustation can be monitored in vivo by ultrasound, making this image based model suitable for assessing novel antibacterial and anti-encrustation therapies.

Crystal structure of the dithiol oxidase DsbA enzyme from proteus mirabilis bound non-covalently to an active site peptide ligand

The disulfide bond forming DsbA enzymes and their DsbB interaction partners are attractive targets for development of antivirulence drugs because both are essential for virulence factor assembly in Gram-negative pathogens. Here we characterize PmDsbA from Proteus mirabilis, a bacterial pathogen increasingly associated with multidrug resistance. PmDsbA exhibits the characteristic properties of a DsbA, including an oxidizing potential, destabilizing disulfide, acidic active site cysteine, and dithiol oxidase catalytic activity. We evaluated a peptide, PWATCDS, derived from the partner protein DsbB and showed by thermal shift and isothermal titration calorimetry that it binds to PmDsbA. The crystal structures of PmDsbA, and the active site variant PmDsbAC30S were determined to high resolution. Analysis of these structures allows categorization of PmDsbA into the DsbA class exemplified by the archetypal Escherichia coli DsbA enzyme. We also present a crystal structure of PmDsbAC30S in complex with the peptide PWATCDS. The structure shows that the peptide binds non-covalently to the active site CXXC motif, the cis-Pro loop, and the hydrophobic groove adjacent to the active site of the enzyme. This high-resolution structural data provides a critical advance for future structure-based design of non-covalent peptidomimetic inhibitors. Such inhibitors would represent an entirely new antibacterial class that work by switching off the DSB virulence assembly machinery.

Native flagellin does not protect mice against an experimental Proteus mirabilis ascending urinary tract infection and neutralizes the protective effect of MrpA fimbrial protein

Proteus mirabilis expresses several virulence factors including MR/P fimbriae and flagella. Bacterial flagellin has frequently shown interesting adjuvant and protective properties in vaccine formulations. However, native P. mirabilis flagellin has not been analyzed so far. Native P. mirabilis flagellin was evaluated as a protective antigen and as an adjuvant in co-immunizations with MrpA (structural subunit of MR/P fimbriae) using an ascending UTI model in the mouse. Four groups of mice were intranasally treated with either MrpA, native flagellin, both proteins and PBS. Urine and blood samples were collected before and after immunization for specific antibodies determination. Cytokine production was assessed in immunized mice splenocytes cultures. Mice were challenged with P. mirabilis, and bacteria quantified in kidneys and bladders. MrpA immunization induced serum and urine specific anti-MrpA antibodies while MrpA coadministered with native flagellin did not. None of the animals developed significant anti-flagellin antibodies. Only MrpA-immunized mice showed a significant decrease of P. mirabilis in bladders and kidneys. Instead, infection levels in MrpA-flagellin or flagellin-treated mice showed no significant differences with the control group. IL-10 was significantly induced in splenocytes of mice that received native flagellin or MrpA-flagellin. Native P. mirabilis flagellin did not protect mice against an ascending UTI. Moreover, it showed an immunomodulatory effect, neutralizing the protective role of MrpA. P. mirabilis flagellin exhibits particular immunological properties compared to other bacterial flagellins.

Elucidating the genetic basis of crystalline biofilm formation in Proteus mirabilis

Proteus mirabilis forms extensive crystalline biofilms on urethral catheters that occlude urine flow and frequently complicate the management of long-term-catheterized patients. Here, using random transposon mutagenesis in conjunction with in vitro models of the catheterized urinary tract, we elucidate the mechanisms underpinning the formation of crystalline biofilms by P. mirabilis. Mutants identified as defective in blockage of urethral catheters had disruptions in genes involved in nitrogen metabolism and efflux systems but were unaffected in general growth, survival in bladder model systems, or the ability to elevate urinary pH. Imaging of biofilms directly on catheter surfaces, along with quantification of levels of encrustation and biomass, confirmed that the mutants were attenuated specifically in the ability to form crystalline biofilms compared with that of the wild type. However, the biofilm-deficient phenotype of these mutants was not due to deficiencies in attachment to catheter biomaterials, and defects in later stages of biofilm development were indicated. For one blocking-deficient mutant, the disrupted gene (encoding a putative multidrug efflux pump) was also found to be associated with susceptibility to fosfomycin, and loss of this system or general inhibition of efflux pumps increased sensitivity to this antibiotic. Furthermore, homologues of this system were found to be widely distributed among other common pathogens of the catheterized urinary tract. Overall, our findings provide fundamental new insight into crystalline biofilm formation by P. mirabilis, including the link between biofilm formation and antibiotic resistance in this organism, and indicate a potential role for efflux pump inhibitors in the treatment or prevention of P. mirabilis crystalline biofilms.

The RNA chaperone Hfq is involved in stress tolerance and virulence in uropathogenic Proteus mirabilis

Hfq is a bacterial RNA chaperone involved in the riboregulation of diverse genes via small noncoding RNAs. Here, we show that Hfq is critical for the uropathogenic Proteus mirabilis to effectively colonize the bladder and kidneys in a murine urinary tract infection (UTI) model and to establish burned wound infection of the rats. In this regard, we found the hfq mutant induced higher IL-8 and MIF levels of uroepithelial cells and displayed reduced intra-macrophage survival. The loss of hfq affected bacterial abilities to handle H2O2 and osmotic pressures and to grow at 50 °C. Relative to wild-type, the hfq mutant had reduced motility, fewer flagella and less hemolysin expression and was less prone to form biofilm and to adhere to and invade uroepithelial cells. The MR/P fimbrial operon was almost switched to the off phase in the hfq mutant. In addition, we found the hfq mutant exhibited an altered outer membrane profile and had higher RpoE expression, which indicates the hfq mutant may encounter increased envelope stress. With the notion of envelope disturbance in the hfq mutant, we found increased membrane permeability and antibiotic susceptibilities in the hfq mutant. Finally, we showed that Hfq positively regulated the RpoS level and tolerance to H2O2 in the stationary phase seemed largely mediated through the Hfq-dependent RpoS expression. Together, our data indicate that Hfq plays a critical role in P. mirabilis to establish UTIs by modulating stress responses, surface structures and virulence factors. This study suggests Hfq may serve as a scaffold molecule for development of novel anti-P. mirabilis drugs and P. mirabilis hfq mutant is a vaccine candidate for preventing UTIs.

Identification of small molecules inhibiting diguanylate cyclases to control bacterial biofilm development

Biofilm formation by pathogenic bacteria is an important virulence factor in the development of numerous chronic infections, thereby causing a severe health burden. Many of these infections cannot be resolved, as bacteria in biofilms are resistant to the host's immune defenses and antibiotic therapy. An urgent need for new strategies to treat biofilm-based infections is critically needed. Cyclic di-GMP (c-di-GMP) is a widely conserved second-messenger signal essential for biofilm formation. The absence of this signalling system in higher eukaryotes makes it an attractive target for the development of new anti-biofilm agents. In this study, the results of an in silico pharmacophore-based screen to identify small-molecule inhibitors of diguanylate cyclase (DGC) enzymes that synthesize c-di-GMP are described. Four small molecules, LP 3134, LP 3145, LP 4010 and LP 1062 that antagonize these enzymes and inhibit biofilm formation by Pseudomonas aeruginosa and Acinetobacter baumannii in a continuous-flow system are reported. All four molecules dispersed P. aeruginosa biofilms and inhibited biofilm development on urinary catheters. One molecule dispersed A. baumannii biofilms. Two molecules displayed no toxic effects on eukaryotic cells. These molecules represent the first compounds identified from an in silico screen that are able to inhibit DGC activity to prevent biofilm formation.

96-well microtiter plates for biofouling simulation in biomedical settings

Microtiter plates with 96 wells are routinely used in biofilm research mainly because they enable high-throughput assays. These platforms are used in a variety of conditions ranging from static to dynamic operation using different shaking frequencies and orbital diameters. The main goals of this work were to assess the influence of nutrient concentration and flow conditions on biofilm formation by Escherichia coli in microtiter plates and to define the operational conditions to be used in order to simulate relevant biomedical scenarios. Assays were performed in static mode and in incubators with distinct orbital diameters using different concentrations of glucose, peptone and yeast extract. Computational fluid dynamics (CFD) was used to simulate the flow inside the wells for shaking frequencies ranging from 50 to 200 rpm and orbital diameters from 25 to 100 mm. Higher glucose concentrations enhanced adhesion of E. coli in the first 24 h, but variation in peptone and yeast extract concentration had no significant impact on biofilm formation. Numerical simulations indicate that 96-well microtiter plates can be used to simulate a variety of biomedical scenarios if the operating conditions are carefully set.

Type 1 fimbriae contribute to catheter-associated urinary tract infections caused by Escherichia coli

Biofilm formation on catheters is thought to contribute to persistence of catheter-associated urinary tract infections (CAUTI), which represent the most frequent nosocomial infections. Knowledge of genetic factors for catheter colonization is limited, since their role has not been assessed using physicochemical conditions prevailing in a catheterized human bladder. The current study aimed to combine data from a dynamic catheterized bladder model in vitro with in vivo expression analysis for understanding molecular factors relevant for CAUTI caused by Escherichia coli. By application of the in vitro model that mirrors the physicochemical environment during human infection, we found that an E. coli K-12 mutant defective in type 1 fimbriae, but not isogenic mutants lacking flagella or antigen 43, was outcompeted by the wild-type strain during prolonged catheter colonization. The importance of type 1 fimbriae for catheter colonization was verified using a fimA mutant of uropathogenic E. coli strain CFT073 with human and artificial urine. Orientation of the invertible element (IE) controlling type 1 fimbrial expression in bacterial populations harvested from the colonized catheterized bladder in vitro suggested that the vast majority of catheter-colonizing cells (up to 88%) express type 1 fimbriae. Analysis of IE orientation in E. coli populations harvested from patient catheters revealed that a median level of ∼73% of cells from nine samples have switched on type 1 fimbrial expression. This study supports the utility of the dynamic catheterized bladder model for analyzing catheter colonization factors and highlights a role for type 1 fimbriae during CAUTI.

Evidence based practice in long term care settings

PURPOSE

The purpose of this manuscript is to discuss the need for use of evidence based practice (EBP) in LTC, the current use of evidence in long term care facilities and what we know about adoption of the use of EBP in LTC.

METHODS

Literature review and reporting of findings from the M-TRAIN study that was a quasi-experimental design to test the effectiveness of an intervention to increase the use of EBPs for urinary incontinence and pain in 48 LTC facilities.

RESULTS

Barriers to adopting EBPs include lack of available time, lack of access to current research literature, limited critical appraisal skills, excessive literature to review, non-receptive organizational culture, limited resources, and limited decision-making authority of staff to implement change. Strategies to promote adoption of EBP include the commitment of management; the culture of the home; leadership; staff knowledge, time, and reward; and facility size, complexity, the extent that members are involved outside the facility, NH chain membership, and high level of private pay residents. Findings from the M-TRAIN add, stability of nurse leader and congruency between the leaders perception of their leadership and the staff's perception of the leadership.

CONCLUSION

There is clear evidence of the need and the benefits to residents of LTC and to the health care system yet adoption of EBP continues to be slow and sporadic. There is also evidence for the process of establishing best evidence and many resources to find the available EBPs. The urgent need now is finding ways to best get the EBPs implemented in LTC. There is growing evidence about best methods to do this but continued research is needed. Clearly, residents in LTC deserve the best care possible and EBPs represent an important vehicle by which to do this.

Hemagglutination and biofilm formation as virulence markers of uropathogenic Escherichia coli in acute urinary tract infections and urolithiasis

INTRODUCTION

Urinary tract infections (UTI) are a major public health concern in developing countries. Most UTIs are caused by E. coli, accounting for up to 90% of community-acquired UTIs (CAUTI). Recurrent UTI is considered as a major risk factor for urolithiasis. Virulence factors like adhesins and biofilm have been extensively studied by authors on UPEC isolated from recurrent UTI. The studies on isolates from infection stones in kidney are scanty. In a prospective study, we aimed to determine the expression of Haemagglutinins, (Type 1 and P fimbriae), Biofilm production and resistance pattern to common antibiotics of Uropathogenic E.coli (UPEC) isolates from Community acquired Acute Urinary Tract Infection(CAUTI) and Urolithiasis.

MATERIALS AND METHODS

A total of 43 UPEC isolates, 23 mid-stream urine (MSU) samples from patients with CAUTI attending Out Patient Departments and 20 from renal calculi of urolithiasis patients at the time of Percutaneous nephrolithostomy (PCNL) were included in the study and the expression of Haemagglutinins,(Type 1 and P fimbriae), Biofilm production and resistance pattern to common antibiotics was assessed.

RESULTS

A total of 43 UPEC isolates 23 from CAUTI and 20 from renal calculi were tested for production of biofilm and hemagglutinins. In CAUTI, biofilm producers were 56.52% and hemagglutinins were detected in all isolates 100%. In urolithiasis, biofilm producers were 100% but hemagglutinins were detected only in 70% of isolates. All isolates were resistant to multiple antibiotics used. CAUTI isolates were susceptible to 3(rd) generation cephalosporins, whereas urolithiasis isolates were resistant to 3(rd) generation cephalosporins and 25% were Extended Spectrum Beta Lactamases ESBL producers.

CONCLUSIONS

HA mediated by type 1 fimbriae plays an important role in CAUTI (P < 0.001 highly significant), whereas, in chronic conditions like urolithiasis, biofilm plays an important role in persistence of infection and the role of hemagglutinins is less.

Characterization of Escherichia coli isolates from hospital inpatients or outpatients with urinary tract infection

Uropathogenic Escherichia coli (UPEC) is the most common cause of community- and hospital-acquired urinary tract infections (UTIs). Isolates from uncomplicated community-acquired UTIs express a variety of virulence traits that promote the efficient colonization of the urinary tract. In contrast, nosocomial UTIs can be caused by E. coli strains that differ in their virulence traits from the community-acquired UTI isolates. UPEC virulence markers are used to distinguish these facultative extraintestinal pathogens, which belong to the intestinal flora of many healthy individuals, from intestinal pathogenic E. coli (IPEC). IPEC is a diarrheagenic pathogen with a characteristic virulence gene set that is absent in UPEC. Here, we characterized 265 isolates from patients with UTIs during inpatient or outpatient treatment at a hospital regarding their phylogenies and IPEC or UPEC virulence traits. Interestingly, 28 of these isolates (10.6%) carried typical IPEC virulence genes that are characteristic of enteroaggregative E. coli (EAEC), Shiga toxin-producing E. coli (STEC), and atypical enteropathogenic E. coli (aEPEC), although IPEC is not considered a uropathogen. Twenty-three isolates harbored the astA gene coding for the EAEC heat-stable enterotoxin 1 (EAST1), and most of them carried virulence genes that are characteristic of UPEC and/or EAEC. Our results indicate that UPEC isolates from hospital patients differ from archetypal community-acquired isolates from uncomplicated UTIs by their spectrum of virulence traits. They represent a diverse group, including EAEC, as well as other IPEC pathotypes, which in addition contain typical UPEC virulence genes. The combination of typical extraintestinal pathogenic E. coli (ExPEC) and IPEC virulence determinants in some isolates demonstrates the marked genome plasticity of E. coli and calls for a reevaluation of the strict pathotype classification of EAEC.

Observation of multicellular spinning behavior of Proteus mirabilis by atomic force microscopy and multifunctional microscopy

This study aimed to observe the multicellular spinning behavior of Proteus mirabilis by atomic force microscopy (AFM) and multifunctional microscopy in order to understand the mechanism underlying this spinning movement and its biological significance. Multifunctional microscopy with charge-coupled device (CCD) and real-time AFM showed changes in cell structure and shape of P. mirabilis during multicellular spinning movement. Specifically, the morphological characteristics of P. mirabilis, multicellular spinning dynamics, and unique movement were observed. Our findings indicate that the multicellular spinning behavior of P. mirabilis may be used to collect nutrients, perform colonization, and squeeze out competitors. The movement characteristics of P. mirabilis are vital to the organism's biological adaptability to the surrounding environment.

From infection to immunotherapy: host immune responses to bacteria at the bladder mucosa

The pathogenesis of urinary tract infection and mechanisms of the protective effect of Bacillus Calmette-Guerin (BCG) therapy for bladder cancer highlight the importance of studying the bladder as a unique mucosal surface. Innate responses to bacteria are reviewed, and although our collective knowledge remains incomplete, we discuss how adaptive immunity may be generated following bacterial challenge in the bladder microenvironment. Interestingly, the widely held belief that the bladder is sterile has been challenged recently, indicating the need for further study of the impact of commensal microorganisms on the immune response to uropathogen infection or intentional instillation of BCG. This review addresses the aspects of bladder biology that have been well explored and defines what still must be discovered about the immunobiology of this understudied organ.

Regulatory and metabolic networks for the adaptation of Pseudomonas aeruginosa biofilms to urinary tract-like conditions

Biofilms of the Gram-negative bacterium Pseudomonas aeruginosa are one of the major causes of complicated urinary tract infections with detrimental outcome. To develop novel therapeutic strategies the molecular adaption strategies of P. aeruginosa biofilms to the conditions of the urinary tract were investigated thoroughly at the systems level using transcriptome, proteome, metabolome and enzyme activity analyses. For this purpose biofilms were grown anaerobically in artificial urine medium (AUM). Obtained data were integrated bioinformatically into gene regulatory and metabolic networks. The dominating response at the transcriptome and proteome level was the adaptation to iron limitation via the broad Fur regulon including 19 sigma factors and up to 80 regulated target genes or operons. In agreement, reduction of the iron cofactor-dependent nitrate respiratory metabolism was detected. An adaptation of the central metabolism to lactate, citrate and amino acid as carbon sources with the induction of the glyoxylate bypass was observed, while other components of AUM like urea and creatinine were not used. Amino acid utilization pathways were found induced, while fatty acid biosynthesis was reduced. The high amounts of phosphate found in AUM explain the reduction of phosphate assimilation systems. Increased quorum sensing activity with the parallel reduction of chemotaxis and flagellum assembly underscored the importance of the biofilm life style. However, reduced formation of the extracellular polysaccharide alginate, typical for P. aeruginosa biofilms in lungs, indicated a different biofilm type for urinary tract infections. Furthermore, the obtained quorum sensing response results in an increased production of virulence factors like the extracellular lipase LipA and protease LasB and AprA explaining the harmful cause of these infections.

A review of the clinical implications of anti-infective biomaterials and infection-resistant surfaces

Infection is currently regarded as the most severe and devastating complication associated to the use of biomaterials. The important social, clinical and economic impacts of implant-related infections are promoting the efforts to obviate these severe diseases. In this context, the development of anti-infective biomaterials and of infection-resistant surfaces is being regarded as the main strategy to prevent the establishment of implant colonisation and biofilm formation by bacteria. In this review, the attention is focused on the biomaterial-associated infections, from which the need for anti-infective biomaterials originates. Biomaterial-associated infections differ markedly for epidemiology, aetiology and severity, depending mainly on the anatomic site, on the time of biomaterial application, and on the depth of the tissues harbouring the prosthesis. Here, the diversity and complexity of the different scenarios where medical devices are currently utilised are explored, providing an overview of the emblematic applicative fields and of the requirements for anti-infective biomaterials.

A scoping review of important urinary catheter induced complications

This study presents a scoping review of the literature on the morbidity and mortality associated with several common complications of urinary catheterization. Data gathered from the open literature were analyzed graphically to gain insights into the most important urinary catheter induced complications. The results reveal that the most significant catheter complications are severe mechanical trauma (perforation, partial urethral damage and urinary leakage), symptomatic bacterial infection, and anaphylaxis, catheter toxicity and hypersensitivity. The data analysis also revealed that the complications with the highest morbidity are all closely related to the mechanical interaction of the catheter with the urethra. This suggests that there is a strong need for urinary catheter design to be improved to minimize mechanical interaction, especially mechanical damage to the urinary tract, and to enhance patient comfort. Several urinary catheter design directions have been proposed based on tribological principles. Among the key recommendations is that catheter manufacturers develop catheter coatings which are both hydrophilic and antibacterial, and which maintain their antibacterial patency for at least 90 days.

Genome Sequence of Proteus mirabilis Strain PR03, Isolated from a Local Hospital in Malaysia

Proteus mirabilis is one of the pathogenic agents that commonly causes urinary tract infections among elderly individuals and long-term catheterized patients. Here, we report a draft genome sequence of Proteus mirabilis strain PR03 (3,932,623 bp, with a G+C content of 38.6%) isolated from a local hospital in Malaysia.

Role of pore-forming toxins in bacterial infectious diseases

Pore-forming toxins (PFTs) are the most common bacterial cytotoxic proteins and are required for virulence in a large number of important pathogens, including Streptococcus pneumoniae, group A and B streptococci, Staphylococcus aureus, Escherichia coli, and Mycobacterium tuberculosis. PFTs generally disrupt host cell membranes, but they can have additional effects independent of pore formation. Substantial effort has been devoted to understanding the molecular mechanisms underlying the functions of certain model PFTs. Likewise, specific host pathways mediating survival and immune responses in the face of toxin-mediated cellular damage have been delineated. However, less is known about the overall functions of PFTs during infection in vivo. This review focuses on common themes in the area of PFT biology, with an emphasis on studies addressing the roles of PFTs in in vivo and ex vivo models of colonization or infection. Common functions of PFTs include disruption of epithelial barrier function and evasion of host immune responses, which contribute to bacterial growth and spreading. The widespread nature of PFTs make this group of toxins an attractive target for the development of new virulence-targeted therapies that may have broad activity against human pathogens.

(1→3)-β-D-Glucan reduces the damages caused by reactive oxygen species induced in human platelets by lipopolysaccharides

LPS (lipopolysaccharide) induces platelet activation and is a well-known fundamental agent of septic shock and disseminated intravascular coagulation (DIC). Biological activity of (1→3)-β-D-glucan is related due to its anti-inflammatory, antioxidant, and antitumor properties. We focus our attention on the (1→3)-β-D-glucan (antiplatelet) properties. The main purpose of our study was to evaluate the influence of (1→3)-β-D-glucan from Saccharomyces cerevisiae on destructive activity of LPS (from Escherichia coli and Pseudomonas aeruginosa) on human blood platelets. We assess biochemically in vitro if (1→3)-β-D-glucan might combat the oxidative stress caused by LPS stroke associated with nitrative and oxidative damages of human platelet biomolecules. We also make an attempt by in silico molecular docking to determine the interactions between the molecules of (1→3)-β-D-glucan and LPS. Our conclusion is that protective mechanism of (1→3)-β-D-glucan against LPS action on blood platelets is due to as well: its antioxidant properties, as to its interaction with LPS-binding region of TLR4-MD-2 complex.

Prevention and treatment of urinary catheter-associated infections

Catheter-associated urinary tract infections (CA-UTIs) are the most common nosocomial infection worldwide. Prolonged catheterization is the most important risk factor for CA-UTIs. As is the case with all device-related infections, the biofilm plays a central role in the pathogenesis of CA-UTIs. The diagnosis is often difficult, given the lack of good diagnostic tests. The most effective way to prevent infection is to limit catheter use and discontinue the catheter when no longer needed. Catheter removal or exchange is also useful in management. This review summarizes and analyzes the results of published studies of CA-UTIs and assesses the role of prevention approaches and management strategies.

Bacterial biofilms: development, dispersal, and therapeutic strategies in the dawn of the postantibiotic era

Biofilm formation constitutes an alternative lifestyle in which microorganisms adopt a multicellular behavior that facilitates and/or prolongs survival in diverse environmental niches. Biofilms form on biotic and abiotic surfaces both in the environment and in the healthcare setting. In hospital wards, the formation of biofilms on vents and medical equipment enables pathogens to persist as reservoirs that can readily spread to patients. Inside the host, biofilms allow pathogens to subvert innate immune defenses and are thus associated with long-term persistence. Here we provide a general review of the steps leading to biofilm formation on surfaces and within eukaryotic cells, highlighting several medically important pathogens, and discuss recent advances on novel strategies aimed at biofilm prevention and/or dissolution.

Lysogenic conversion and phage resistance development in phage exposed Escherichia coli biofilms

In this study, three-day old mature biofilms of Escherichia coli were exposed once to either a temperate Shiga-toxin encoding phage (H-19B) or an obligatory lytic phage (T7), after which further dynamics in the biofilm were monitored. As such, it was found that a single dose of H-19B could rapidly lead to a near complete lysogenization of the biofilm, with a subsequent continuous release of infectious H-19B particles. On the other hand, a single dose of T7 rapidly led to resistance development in the biofilm population. Together, our data indicates a profound impact of phages on the dynamics within structured bacterial populations.

Initiation of swarming motility by Proteus mirabilis occurs in response to specific cues present in urine and requires excess L-glutamine

Proteus mirabilis, a leading cause of catheter-associated urinary tract infection (CaUTI), differentiates into swarm cells that migrate across catheter surfaces and medium solidified with 1.5% agar. While many genes and nutrient requirements involved in the swarming process have been identified, few studies have addressed the signals that promote initiation of swarming following initial contact with a surface. In this study, we show that P. mirabilis CaUTI isolates initiate swarming in response to specific nutrients and environmental cues. Thirty-three compounds, including amino acids, polyamines, fatty acids, and tricarboxylic acid (TCA) cycle intermediates, were tested for the ability to promote swarming when added to normally nonpermissive media. L-Arginine, L-glutamine, DL-histidine, malate, and DL-ornithine promoted swarming on several types of media without enhancing swimming motility or growth rate. Testing of isogenic mutants revealed that swarming in response to the cues required putrescine biosynthesis and pathways involved in amino acid metabolism. Furthermore, excess glutamine was found to be a strict requirement for swarming on normal swarm agar in addition to being a swarming cue under normally nonpermissive conditions. We thus conclude that initiation of swarming occurs in response to specific cues and that manipulating concentrations of key nutrient cues can signal whether or not a particular environment is permissive for swarming.

Identification of serotypes and virulence markers of Escherichia coli isolated from human stool and urine samples in Egypt

PURPOSE

Haemorrhagic colitis and haemolytic-uremic syndrome are associated with Shiga-toxin producing Escherichia coli (STEC). There are others DEC (Diarrhoeagenic E. coli) pathotypes responsible for outbreaks and others toxins associated to these. Most clinical signs of disease arise as a consequence of the production of Shiga toxin 1 (Stx1), Stx2 or combinations of these toxins. Other major virulence factors include E. coli haemolysin (hlyA), and intimin, the product of the eaeA gene that is involved in the attaching and effacing adherence phenotype.

MATERIALS AND METHODS

In this study, the PCR assay was used to detect 12 E. coli genes associated with virulence (stx1, stx2, hylA, Flic h7 , stb, F41, K99, sta, F17, LT-I, LT-II and eaeA).

RESULTS

A total of 108 E. coli strains were serotyped into 64 typable strains. The investigated strains from the stool, 8/80 (10%) strains were O 164:K, while the 56/110 strains isolated from the urine were O126:K71 (44/110, 40%) and O 86:K 61 (12/110, 11%). The distribution pattern of the detected virulence genes was observed to be in the following order: F17 (10% from the stool and 44% from the urine), Sta (10% from the stool), hylA (10% from the stool and 44% from the urine), Stb (44% from the urine) and stx1 (27% from the urine). The 8 faecal strains encoded a combination of the F17, Sta and hylA genes, while the 56 urine strains encoded a combination of the F17 0+ Stb + hylA (44/110, 40%) and Stx1 only (12/60, 20%).

CONCLUSION

This is the first report on the molecular characterization of E. coli diarrhoeagenic strains in Egypt and the first report on the potential role of E. coli in diarrhoea and urinary tract infections in a localized geographic area where the people engage in various occupational activities.

Rapid detection of urinary tract infections caused by Proteus spp. using PNA-FISH

We developed a fluorescence in situ hybridization (FISH) method for the rapid detection of Proteus spp. in urine, using a novel peptide nucleic acid (PNA) probe. Testing on 137 urine samples from patients with urinary tract infections has shown specificity and sensitivity values of 98 % (95 % CI, 93.2-99.7) and 100 % (95 % CI, 80,8-100), respectively, when compared with CHROMagar Orientation medium. Results indicate that PNA-FISH is a reliable alternative to traditional culture methods and can reduce the diagnosis time to approximately 2 h.

Anti-biofilm activity of silver nanoparticles against different microorganisms

Biofilms confer protection from adverse environmental conditions and can be reservoirs for pathogenic organisms and sources of disease outbreaks, especially in medical devices. The goal of this research was to evaluate the anti-biofilm activities of silver nanoparticles (AgNPs) against several microorganisms of clinical interest. The antimicrobial activity of AgNPs was tested within biofilms generated under static conditions and also under high fluid shears conditions using a bioreactor. A 4-log reduction in the number of colony-forming units of Pseudomonas aeruginosa was recorded under turbulent fluid conditions in the CDC reactor on exposure to 100 mg ml(-1) of AgNPs. The antibacterial activity of AgNPs on various microbial strains grown on polycarbonate membranes is reported. In conclusion, AgNPs effectively prevent the formation of biofilms and kill bacteria in established biofilms, which suggests that AgNPs could be used for prevention and treatment of biofilm-related infections. Further research and development are necessary to translate this technology into therapeutic and preventive strategies.

Proteus sp. – an opportunistic bacterial pathogen – classification, swarming growth, clinical significance and virulence factors

The genus Proteus belongs to the Enterobacteriaceae family, where it is placed in the tribe Proteeae, together with the genera Morganella and Providencia. Currently, the genus Proteus consists of five species: P. mirabilis, P. vulgaris, P. penneri, P. hauseri and P. myxofaciens, as well as three unnamed Proteus genomospecies. The most defining characteristic of Proteus bacteria is a swarming phenomenon, a multicellular differentiation process of short rods to elongated swarmer cells. It allows population of bacteria to migrate on solid surface. Proteus bacteria inhabit the environment and are also present in the intestines of humans and animals. These microorganisms under favorable conditions cause a number of infections including urinary tract infections (UTIs), wound infections, meningitis in neonates or infants and rheumatoid arthritis. Therefore, Proteus is known as a bacterial opportunistic pathogen. It causes complicated UTIs with a higher frequency, compared to other uropathogens. Proteus infections are accompanied by a formation of urinary stones, containing struvite and carbonate apatite. The virulence of Proteus rods has been related to several factors including fimbriae, flagella, enzymes (urease - hydrolyzing urea to CO2 and NH3, proteases degrading antibodies, tissue matrix proteins and proteins of the complement system), iron acqusition systems and toxins: hemolysins, Proteus toxin agglutinin (Pta), as well as an endotoxin - lipopolysaccharide (LPS). Proteus rods form biofilm, particularly on the surface of urinary catheters, which can lead to serious consequences for patients. In this review we present factors involved in the regulation of swarming phenomenon, discuss the role of particular pathogenic features of Proteus spp., and characterize biofilm formation by these bacteria.

Whole-genome sequencing and identification of Morganella morganii KT pathogenicity-related genes

BACKGROUND

The opportunistic enterobacterium, Morganella morganii, which can cause bacteraemia, is the ninth most prevalent cause of clinical infections in patients at Changhua Christian Hospital, Taiwan. The KT strain of M. morganii was isolated during postoperative care of a cancer patient with a gallbladder stone who developed sepsis caused by bacteraemia. M. morganii is sometimes encountered in nosocomial settings and has been causally linked to catheter-associated bacteriuria, complex infections of the urinary and/or hepatobiliary tracts, wound infection, and septicaemia. M. morganii infection is associated with a high mortality rate, although most patients respond well to appropriate antibiotic therapy. To obtain insights into the genome biology of M. morganii and the mechanisms underlying its pathogenicity, we used Illumina technology to sequence the genome of the KT strain and compared its sequence with the genome sequences of related bacteria.

RESULTS

The 3,826,919-bp sequence contained in 58 contigs has a GC content of 51.15% and includes 3,565 protein-coding sequences, 72 tRNA genes, and 10 rRNA genes. The pathogenicity-related genes encode determinants of drug resistance, fimbrial adhesins, an IgA protease, haemolysins, ureases, and insecticidal and apoptotic toxins as well as proteins found in flagellae, the iron acquisition system, a type-3 secretion system (T3SS), and several two-component systems. Comparison with 14 genome sequences from other members of Enterobacteriaceae revealed different degrees of similarity to several systems found in M. morganii. The most striking similarities were found in the IS4 family of transposases, insecticidal toxins, T3SS components, and proteins required for ethanolamine use (eut operon) and cobalamin (vitamin B12) biosynthesis. The eut operon and the gene cluster for cobalamin biosynthesis are not present in the other Proteeae genomes analysed. Moreover, organisation of the 19 genes of the eut operon differs from that found in the other non-Proteeae enterobacterial genomes.

CONCLUSIONS

This is the first genome sequence of M. morganii, which is a clinically relevant pathogen. Comparative genome analysis revealed several pathogenicity-related genes and novel genes not found in the genomes of other members of Proteeae. Thus, the genome sequence of M. morganii provides important information concerning virulence and determinants of fitness in this pathogen.

Activity of Proteus mirabilis FliL is viscosity dependent and requires extragenic DNA

Proteus mirabilis is a urinary tract pathogen and well known for its ability to move over agar surfaces by flagellum-dependent swarming motility. When P. mirabilis encounters a highly viscous environment, e.g., an agar surface, it differentiates from short rods with few flagella to elongated, highly flagellated cells that lack septa and contain multiple nucleoids. The bacteria detect a surface by monitoring the rotation of their flagellar motors. This process involves an enigmatic flagellar protein called FliL, the first gene in an operon (fliLMNOPQR) that encodes proteins of the flagellar rotor switch complex and flagellar export apparatus. We used a fliL knockout mutant to gain further insight into the function of FliL. Loss of FliL results in cells that cannot swarm (Swr(-)) but do swim (Swm(+)) and produces cells that look like wild-type swarmer cells, termed "pseudoswarmer cells," that are elongated, contain multiple nucleoids, and lack septa. Unlike swarmer cells, pseudoswarmer cells are not hyperflagellated due to reduced expression of flaA (the gene encoding flagellin), despite an increased transcription of both flhD and fliA, two positive regulators of flagellar gene expression. We found that defects in fliL prevent viscosity-dependent sensing of a surface and viscosity-dependent induction of flaA transcription. Studies with fliL cells unexpectedly revealed that the fliL promoter, fliL coding region, and a portion of fliM DNA are needed to complement the Swr(-) phenotype. The data support a dual role for FliL as a critical link in sensing a surface and in the maintenance of flagellar rod integrity.

Characterization of bacterial biofilms formed on urinary catheters

BACKGROUND

The formation of bacterial biofilms on urinary catheters is a leading cause of urinary tract infections in intensive care units. Cytobacteriological examination of urine from patients is often misleading, due to the formation of these biofilms. Therefore, characterizing these biofilms and identifying the bacterial species residing on the surface of catheters are of major importance.

METHODS

We studied the formation of biofilms on the inner surface of urinary catheters using microbiological culture techniques, with the direct contact of catheter pieces with blood agar. The bacterial species on the surface were characterized by scanning electron microscopy, and the kinetic profile of biofilm formation on a silicone substrate for an imipenem-resistant Acinetobacter baumannii bacterium was evaluated with a crystal violet staining assay.

RESULTS

The bacterial species that constituted these biofilms were identified as a variety of gram-negative bacilli, with a predominance of strains belonging to Pseudomonas aeruginosa. The other isolated strains belonged to A baumannii and Klebsiella ornithinolytica. Kinetic profiling of biofilm formation identified the transient behavior of A baumannii between its biofilm and planktonic state. This strain was highly resistant to all of the antibiotics tested except colistin. Scanning electron microscopy images showed that the identified isolated species formed a dense and interconnected network of cellular multilayers formed from either a single cell or from different species that were surrounded and enveloped by a protective matrix.

CONCLUSIONS

Microbiological analysis of the intraluminal surface of the catheter is required for true identification of the causative agents of catheter-associated urinary tract infections. This approach, combined with a routine cytobacteriological examination of urine, allows for the complete characterization of biofilm-associated species, and also may help prevent biofilm formation in such devices and help guide optimum antibiotic treatment.

Changes in peptidoglycan structure and metabolism during differentiation of Proteus mirabilis into swarmer cells

The O-acetylation of peptidoglycan in Gram-negative bacteria occurs specifically at the C-6 hydroxyl group of muramoyl residues. The level of peptidoglycan O-acetylation was found to decrease from 51% to 29% upon differentiation of Proteus mirabilis vegetative cells to swarmers. This decrease was accompanied by a change in the muropeptide composition of the peptidoglycan. In particular, the content of anhydromuropeptides increased, while the amount of Lys-Lys-muropeptides arising from bound lipoprotein decreased. These changes together with a shift in proportion of larger muropeptides suggested a decrease in average chain length of the muropeptides from swarmer cells. Zymography using SDS-PAGE gels containing either O-acetylated or chemically de-O-acetylated peptidoglycan was used to monitor the activity of specific autolysins during the differentiation of vegetative to swarming cells of P. mirabilis. A 43 kDa autolysin with increased specificity for O-acetylated peptidoglycan was detected in vegetative cells, but its activity appeared to decrease as the cells began to differentiate, while the levels of 3 other autolysins with apparent specificity for non-O-acetylated peptidoglycan increased. These changes are discussed in relation to the autolysin profile of the bacteria and the changes in peptidoglycan composition with cell differentiation.

Merging mythology and morphology: the multifaceted lifestyle of Proteus mirabilis

Proteus mirabilis, named for the Greek god who changed shape to avoid capture, has fascinated microbiologists for more than a century with its unique swarming differentiation, Dienes line formation and potent urease activity. Transcriptome profiling during both host infection and swarming motility, coupled with the availability of the complete genome sequence for P. mirabilis, has revealed the occurrence of interbacterial competition and killing through a type VI secretion system, and the reciprocal regulation of adhesion and motility, as well as the intimate connections between metabolism, swarming and virulence. This Review addresses some of the unique and recently described aspects of P. mirabilis biology and pathogenesis, and emphasizes the potential role of this bacterium in single-species and polymicrobial urinary tract infections.

Application of a nanotechnology antimicrobial spray to prevent lower urinary tract infection: a multicenter urology trial

Background

Catheter-associated urinary tract infection (CAUTI) is a common nosocomial device-associated infection. It is now recognized that the high infection rates were caused by the formation of biofilm on the surface of the catheters that decreases the susceptibility to antibiotics and results in anti-microbial resistance.

In this study, we performed an in vitro test to explore the mechanism of biofilm formation and subsequently conducted a multi-center clinical trial to investigate the efficacy of CAUTI prevention with the application of JUC, a nanotechnology antimicrobial spray.

Methods

Siliconized latex urinary catheters were cut into fragments and sterilized by autoclaving. The sterilized sample fragments were randomly divided into the therapy and control group, whereby they were sprayed with JUC and distilled water respectively and dried before use.

The experimental standard strains of Escherichia coli (E. coli) were isolated from the urine samples of patients. At 16 hours and 7 days of incubation, the samples were extracted for confocal laser scanning microscopy.

A total of 1,150 patients were accrued in the clinical study. Patients were randomized according to the order of surgical treatment. The odd array of patients was assigned as the therapy group (JUC), and the even array of patients was assigned as the control group (normal saline).

Results

After 16 hours of culture, bacterial biofilm formed on the surface of sample fragments from the control group. In the therapy group, no bacterial biofilm formation was observed on the sample fragments. No significant increase in bacterial colony count was observed in the therapy group after 7 days of incubation.

On the 7th day of catheterization, urine samples were collected for bacterial culture before extubation. Significant difference was observed in the incidence of bacteriuria between the therapy group and control group (4.52% vs. 13.04%, p < 0.001).

Conclusions

In this study, the effectiveness of JUC in preventing CAUTI in a hospital setting was demonstrated in both in vitro and clinical studies.

Evidence for the involvement of the anthranilate degradation pathway in Pseudomonas aeruginosa biofilm formation

Bacterial biofilms are complex cell communities found attached to surfaces and surrounded by an extracellular matrix composed of exopolysaccharides, DNA, and proteins. We investigated the whole-genome expression profile of Pseudomonas aeruginosa sessile cells (SCs) present in biofilms developed on a glass wool substratum. The transcriptome and proteome of SCs were compared with those of planktonic cell cultures. Principal component analysis revealed a biofilm-specific gene expression profile. Our study highlighted the overexpression of genes controlling the anthranilate degradation pathway in the SCs grown on glass wool for 24 h. In this condition, the metabolic pathway that uses anthranilate for Pseudomonas quinolone signal production was not activated, which suggested that anthranilate was primarily being consumed for energy metabolism. Transposon mutants defective for anthranilate degradation were analyzed in a simple assay of biofilm formation. The phenotypic analyses confirmed that P. aeruginosa biofilm formation partially depended on the activity of the anthranilate degradation pathway. This work points to a new feature concerning anthranilate metabolism in P. aeruginosa SCs.

Combinatorial small-molecule therapy prevents uropathogenic Escherichia coli catheter-associated urinary tract infections in mice

Catheter-associated urinary tract infections (CAUTIs) constitute the majority of nosocomial urinary tract infections (UTIs) and pose significant clinical challenges. These infections are polymicrobial in nature and are often associated with multidrug-resistant pathogens, including uropathogenic Escherichia coli (UPEC). Urinary catheterization elicits major histological and immunological alterations in the bladder that can favor microbial colonization and dissemination in the urinary tract. We report that these biological perturbations impact UPEC pathogenesis and that bacterial reservoirs established during a previous UPEC infection, in which bacteriuria had resolved, can serve as a nidus for subsequent urinary catheter colonization. Mannosides, small molecule inhibitors of the type 1 pilus adhesin, FimH, provided significant protection against UPEC CAUTI by preventing bacterial invasion and shifting the UPEC niche primarily to the extracellular milieu and on the foreign body. By doing so, mannosides potentiated the action of trimethoprim-sulfamethoxazole in the prevention and treatment of CAUTI. In this study, we provide novel insights into UPEC pathogenesis in the context of urinary catheterization, and demonstrate the efficacy of novel therapies that target critical mechanisms for this infection. Thus, we establish a proof-of-principle for the development of mannosides to prevent and eventually treat these infections in the face of rising antibiotic-resistant uropathogens.

Biofilm formation of Klebsiella pneumoniae on urethral catheters requires either type 1 or type 3 fimbriae

Urinary catheters are standard medical devices utilized in both hospital and nursing home settings, but are associated with a high frequency of catheter-associated urinary tract infections (CAUTI). In particular, biofilm formation on the catheter surface by uropathogens such as Klebsiella pneumoniae causes severe problems. Here we demonstrate that type 1 and type 3 fimbriae expressed by K. pneumoniae enhance biofilm formation on urinary catheters in a catheterized bladder model that mirrors the physico-chemical conditions present in catheterized patients. Furthermore, we show that both fimbrial types are able to functionally compensate for each other during biofilm formation on urinary catheters. In situ monitoring of fimbrial expression revealed that neither of the two fimbrial types is expressed when cells are grown planktonically. Interestingly, during biofilm formation on catheters, both fimbrial types are expressed, suggesting that they are both important in promoting biofilm formation on catheters. Additionally, transformed into and expressed by a nonfimbriated Escherichia coli strain, both fimbrial types significantly increased biofilm formation on catheters compared with the wild-type E. coli strain. The widespread occurrence of the two fimbrial types in different species of pathogenic bacteria stresses the need for further assessment of their role during urinary tract infections.

Multidrug-resistant Proteus mirabilis bloodstream infections: risk factors and outcomes

Our aims were to identify (i) risk factors associated with the acquisition of multidrug-resistant (MDR, to 3 or more classes of antimicrobials) Proteus mirabilis isolates responsible for bloodstream infections (BSIs) and (ii) the impact on mortality of such infections. Risk factors for acquiring MDR P. mirabilis BSIs were investigated in a case-case-control study; those associated with mortality were assessed by comparing survivors and nonsurvivors in a cohort study. The population consisted of 99 adult inpatients with P. mirabilis BSIs identified by our laboratory over an 11-year period (1999 to 2009), 36 (33.3%) of which were caused by MDR strains, and the overall 21-day mortality rate was 30.3%. Acquisition of an MDR strain was independently associated with admission from a long-term care facility (odds ratio [OR], 9.78; 95% confidence interval [CI], 1.94 to 49.16), previous therapy with fluoroquinolones (OR, 5.52; 95% CI, 1.30 to 23.43) or oxyimino-cephalosporins (OR, 4.72; 95% CI, 1.31 to 16.99), urinary catheterization (OR, 3.89; 95% CI, 1.50 to 10.09), and previous hospitalization (OR, 2.68; 95% CI, 10.4 to 6.89). Patients with MDR P. mirabilis BSIs received inadequate initial antimicrobial therapy (IIAT, i.e., treatment with drugs to which the isolate displayed in vitro resistance) more frequently than those with non-MDR infections; they also had increased mortality and (for survivors) longer post-BSI-onset hospital stays. In multivariate regression analysis, 21-day mortality was associated with septic shock at BSI onset (OR, 12.97; 95% CI, 32.2 to 52.23), P. mirabilis isolates that were MDR (OR, 6.62; 95% CI, 16.4 to 26.68), and IIAT (OR, 9.85; 95% CI, 26.7 to 36.25), the only modifiable risk factor of the 3. These findings can potentially improve clinicians' ability to identify P. mirabilis BSIs likely to be MDR, thereby reducing the risk of IIAT--a major risk factor for mortality in these cases--and facilitating the prompt implementation of appropriate infection control measures.

Urinary catheter-associated infections

Catheter-acquired urinary infection is the most common device-associated healthcare-acquired infection. Although most patients are asymptomatic, symptomatic infection may occur and is associated with increased morbidity and costs. Long-term indwelling catheters are associated with more complex microbiology and greater morbidity than short-term catheters. The most effective way to prevent these infections is to restrict indwelling urinary catheter use to limited indications, and to discontinue use of a catheter as soon as feasible. Alternate means of managing bladder emptying, including external condom catheters for men and intermittent catheterization for patients with neurologic impairment of bladder emptying, should be used when possible.

Bacteriuria and antibiotic resistance in catheter urine specimens following radical prostatectomy

OBJECTIVE

There are increasing reports of infectious complications following prostate biopsy due to fluoroquinolone resistance. To determine infectious complications at catheter removal following radical prostatectomy (RP), another setting in daily urological practice where fluoroquinolone prophylaxis is frequently used.

MATERIALS AND METHODS

We prospectively examined urine culture results collected from 334 RP patients immediately prior to catheter removal. Patients received prophylactic antibiotics 1 day before, the day of, and for 5 days after catheter removal. Culture results were reviewed for bacterial species and antimicrobial susceptibilities. Patients with positive urine cultures resistant to the prophylactic antibiotic were switched to culture-specific antibiotic therapy and underwent follow-up culture. The frequency of urinary tract infection (UTI), complications, additional antibiotic therapy, and repeat urine cultures was determined within 60 days.

RESULTS

Of the 334 patients identified, 203 (61%) had cultures with no bacterial growth, and 48 (14%) had colony counts of <1,000 bacteria or Candida albicans and received no further antibiotics. The remaining 83 (25%) had positive culture results, of which 7% were resistant to ciprofloxacin. Twenty-four bacterial species were identified, with Pseudomonas aeruginosa (5%) Escherichia coli (4%), and Staphylococcus epidermidis (3%) being the most frequent. Only two (0.6%) men developed clinical symptoms consistent with UTI (i.e., suprapubic pain, fever) prior to catheter removal, and no serious complications occurred.

CONCLUSIONS

A substantial proportion of RP patients have positive urine cultures at the time of catheter removal, despite the administration of prophylactic fluoroquinolone antibiotics. Potentially virulent organisms are commonly cultured, and ciprofloxacin resistance is frequent. However, outcomes are favorable when culture-specific oral antibiotic therapy is initiated.

Rapid typing of extended-spectrum β-lactamase- and carbapenemase-producing Escherichia coli and Klebsiella pneumoniae isolates by use of SpectraCell RA

Enterobacteriaceae are important pathogens of both nosocomial and community-acquired infections. In particular, strains with broad-spectrum beta-lactamases increasingly cause problems in health care settings. Rapid and reliable typing systems are key tools to identify transmission, so that targeted infection control measures can be taken. In this study, we evaluated the performance of Raman spectroscopic analysis (RA) for the typing of multiresistant Escherichia coli and Klebsiella pneumoniae isolates using the SpectraCell RA bacterial strain analyzer (River Diagnostics). Analysis of 96 unrelated isolates revealed that RA generated highly reproducible spectra and exhibited a discriminatory power that is comparable to pulsed-field gel electrophoresis. Furthermore, adequate results were obtained for three collections of clinical isolates. RA was able to discriminate outbreak-related isolates from isolates that were not involved in an outbreak or transmission. Furthermore, it was found that the RA approach recognized clones, irrespective of the extended-spectrum β-lactamase type. It can be concluded that RA is a suitable typing technique for E. coli and K. pneumoniae isolates. Combining high reproducibility, speed, and ease-of-use, this technique may play an important role in monitoring the epidemiology of these important nosocomial species.

An indwelling urinary catheter for the 21st century

What's known on the subject? and What does the study add? A vast literature has been published on the prevalence, morbidity and microbiology of catheter-associated urinary tract infections. Research and development in recent years has focused on producing antibacterial coatings for the indwelling Foley catheter with insufficient attention to its design. This article provides a critical examination of the design of the indwelling Foley catheter. Design specifications are outlined for a urine collection device that should reduce the vulnerability of catheterised urinary tract to infection. The indwelling urinary catheter is the most common cause of infections in hospitals and other healthcare facilities [1]. As long ago as 1958, Paul Beeson [2] warned '… the decision to use this instrument should be made with the knowledge that it involves the risk of producing a serious disease which is often difficult to treat'. Since then, scientific studies have progressed revealing a greater understanding of the bladder's defence mechanisms against infection and how they are undermined by the Foley catheter [3-5]. In addition, the complications caused by the development of bacterial biofilms on catheters have been recognised and the ways in which these bacterial communities develop on catheters have become clear [5,6]. It is now obvious that fundamental problems with the basic design of the catheter, which has changed little since it was introduced into urological practice by Dr Fredricc Foley in 1937 [7], induce susceptibility to infection. These issues need to be addressed urgently if we are to produce a device suitable for use in the 21st century.