Aetiology and antibiotic resistance patterns of urinary tract infections in the elderly: a 6-month study

Antibiotic resistances of Pseudomonas aeruginosa and Acinetobacter baumannii in urine cultures: experience in a hospital of Southeast Spain

The objectives of this study were to perform a systematic review of publications between 2010 and 2021 on the antibiotic resistance of Pseudomonas aeruginosa and Acinetobacter baumannii from urinary tract infections and to analyze changes over time in hospital urine cultures from 2016 through 2021. The literature was searched, and a retrospective cross-sectional descriptive study was performed in the hospital. Out of 21 838 positive urine cultures, 3.86% were due to P. aeruginosa and 0.44% were due to A. baumannii. For P. aeruginosa, lower resistance rates were observed to virtually all tested antibiotics than were obtained in the systematic review, and the present series of hospital samples showed an in vitro resistance rate <10% to ceftazidime, cefepime, meropenem, piperacillin-tazobactam, amikacin, tobramycin, and colistin. For A. baumannii, the resistance rates to almost all antibiotics were higher in the present series than in the systematic review, being lowest to colistin (10%). Both microorganisms show reduced in vitro susceptibility to some antibiotics during the years of the COVID-19 pandemic in comparison to previous years. In our setting, both piperacillin-tazobactam and meropenem can be recommended for the empirical treatment of UTIs by P. aeruginosa, whereas only colistin can be recommended for UTIs by A. baumannii.

Epidemiology and characterization of Providencia stuartii isolated from hospitalized patients in southern Brazil: a possible emerging pathogen

This study aimed to characterize the virulence factors and antimicrobial resistance of Providencia stuartii , an opportunistic pathogen that causes human infections. We examined 45 isolates of P. stuartii both genotypically and phenotypically by studying their adherence to HeLa cells, biofilm formation, cytotoxicity and antimicrobial resistance, and analysed their genomes for putative virulence and resistance genes. This study found that most isolates possessed multiple virulence genes, including fimA, mrkA, fptA, iutA, ireA and hlyA, and were cytotoxic to Vero cells. All the isolates were resistant to amoxicillin plus clavulanic acid, levofloxacin and sulfamethoxazole plus trimethoprim, and most were resistant to ceftriaxone and cefepime. All isolates harboured extended-spectrum beta-lactamase coding genes such as bla CTX-M-2 and 23/45(51.11 %) of them also harboured bla CTX-M-9. The gene KPC-2 (carbapenemase) was detected in 8/45(17.77 %) isolates. This study also found clonality among the isolates, indicating the possible spread of the pathogen among patients at the hospital. These results have significant clinical and epidemiological implications and emphasize the importance of a continued understanding of the virulence and antimicrobial resistance of this pathogen for the prevention and treatment of future infections.

Socialization of Providencia stuartii Enables Resistance to Environmental Insults

Providencia stuartii is a highly social pathogen responsible for nosocomial chronic urinary tract infections. The bacterium indeed forms floating communities of cells (FCC) besides and prior-to canonical surface-attached biofilms (SAB). Within P. stuartii FCC, cells are riveted one to another owing to by self-interactions between its porins, viz. Omp-Pst1 and Omp-Pst2. In pathophysiological conditions, P. stuartii is principally exposed to high concentrations of urea, ammonia, bicarbonate, creatinine and to large variations of pH, questioning how these environmental cues affect socialization, and whether formation of SAB and FCC protects cells against those. Results from our investigations indicate that FCC and SAB can both form in the urinary tract, endowing cells with increased resistance and fitness. They additionally show that while Omp-Pst1 is the main gateway allowing penetration of urea, bicarbonate and ammonia into the periplasm, expression of Omp-Pst2 enables resistance to them.

Providencia heimbachae Associated with Post-weaning Diarrhea in Piglets: Identification, Phenotype, and Pathogenesis

Despites Providencia heimbachae has been isolated from human, penguin, and bovine fetus, relatively little information is available regarding the pathogenicity and biologic characteristics of P. heimbachae. Here, we report that investigation of post-weaning diarrhea yielded bacterial isolates identified as P. heimbachae based on the biochemical tests and 16S ribosomal DNA sequence analysis. The two isolates were positive for utilization of Malonate, no gas production from glucose, and non-fermentation of D-mannitol, D-Galactose, and L-Rhamnose that were different from those of the type strain, and both of them have the ability of adhesion and invasion to IPEC-J2 cells, and were resistant to 21 out of the 41 antibiotics tested. In addition, the isolate 99101 was highly pathogenic to mice and piglets. Histopathology studies on nerve tissue of piglets that developed hindlimb paralysis showed microglia cell infiltration and neuron damage in the spinal cord. Notably, the strains could grow under low temperature (4 °C), which raise attention of a new risk factor for food safety. To the best of our knowledge, this is the first report of P. heimbachae strain caused post-weaning diarrhea in piglets in both natural and experimental conditions. These findings extended the knowledge of P. heimbachae as an important zoonotic agent, which should be given more attention during surveillance and diagnostics.

Genomic and biological characterization of vB_PvuS_Pm34, a novel lytic bacteriophage that infects Proteus vulgaris

Proteus phage vB_PvuS_Pm34 (Pm34) isolated from the sewage, is a novel virus specific to Proteus vulgaris. Pm34 belonged to the family Siphovirodae with an icosahedron capsid head and a non-contractile tail. Its genome was 39,558 bp in length with a G + C content of 41.4%. Similarity analysis showed that Pm34 shared low identities of 27.6%-38.4% with any other Proteus phages, but had the 96% high identity with Proteus mirabilis AOUC-001. In the genome of Pm34, 70 open reading frames was deduced and 32 had putative functions including integrase and host lysis proteins. No tRNAs, antibiotic resistance and virulence genes were detected. Pm 34 presented a broad pH (4-8) and good temperature tolerance (<40 °C). This is the first report of the bacteriophage specific to P. vulgaris, which can enrich the knowledge of bacteriophages of Prouteus bacteria and provide the possibility for the alternative treatment of P. vulgaris infection.

Antibiotic-resistant pathogens associated with urinary tract infections in nursing homes: Summary of data reported to the National Healthcare Safety Network Long-Term Care Facility Component, 2013-2017

OBJECTIVE

Antibiotic resistance (AR) is a growing and highly prevalent problem in nursing homes. We describe selected AR phenotypes from pathogens causing urinary tract infections (UTIs) reported by nursing homes to the National Healthcare Safety Network (NHSN).

DESIGN

Pathogens and antibiotic susceptibility testing results for UTI events in nursing homes between January 2013 and December 2017 were analyzed. The pathogen distribution and pooled mean proportion of isolates that tested resistant to select antibiotic agents are reported.

SETTING AND PARTICIPANTS

US nursing homes voluntarily participating in the Long-Term Care Facility component of the NHSN.

RESULTS

Overall, 243 nursing homes reported 1 or more UTIs: 121 (50%) were nonprofit facilities, median bed size was 91 (range: 9-801), and average occupancy was 87%. In total, 6,157 pathogens were reported for 5,485 UTI events. Moreover, 9 pathogens accounted for 90% of all reported UTIs; the 3 most frequently identified were Escherichia coli (41%), Proteus species (14%), and Klebsiella pneumoniae/oxytoca (13%). Among E. coli, fluoroquinolone, and extended-spectrum cephalosporin resistance were most prevalent (50% and 20%, respectively). Although Staphylococcus aureus and Enterococcus faecium represented <5% of pathogens reported, they had the highest rates of resistance (67% methicillin resistant and 60% vancomycin resistant, respectively). Multidrug resistance was most common in Pseudomonas aeruginosa (11%). For the resistant phenotypes we assessed, 36% of all UTIs reported were associated with a resistant pathogen.

CONCLUSIONS

This is the first summary of AR among common pathogens causing UTIs reported to NHSN by nursing homes. Improved understanding of the resistance burden among common infections helps inform facility infection prevention and antibiotic stewardship efforts.

Appropriate use of antibiotics: an unmet need

Increasing bacterial resistance combined with a steady decline in the discovery of new antibiotics has resulted in a global healthcare crisis. Overuse of antibiotics, for example, in the poultry and cattle industry, and misuse and improper prescription of antibiotics are leading causes of multidrug resistance (MDR). The increasing use of antibiotics, particularly in developing countries, is a big concern for antibiotic resistance and can cause other health threats such as increased risk of recurrent infections and increased risk of cardiovascular death with chronic use of macrolides. Carbapenems are the last line of defense in many cases of resistant infection, but trends show that resistance against these agents is also increasing. This narrative review is based on relevant literature according to the experience and expertise of the authors and presents an overview of the current knowledge on antibiotic resistance, the key driving factors, and possible strategies to tackle antibiotic resistance. Collectively, studies show that hospital-wide antibiotic stewardship programs are effective in decreasing the spread of antibacterial resistance. As resistance varies according to local patterns of use, it is essential to observe the epidemiology at both a regional and an institutional level. Furthermore, adaptation of clinical guidelines is necessary, particularly for inpatient care. Future guidelines should include a justification step for continued treatment of antibiotic treatments and criteria for selection of antibiotics at the start of treatment. Nonantibiotic prevention strategies can limit infections and should also be considered in treatment plans. Vaccines against MDR organisms have shown some efficacy in phase II trials in critical care patients. Nonimmunogenic and microbiologic treatment options such as fecal transplants may be particularly important for elderly and immune-compromised patients.

Antimicrobial Resistance of Uropathogenic Escherichia coli from Elderly Patients at a General Hospital, Argentina

Background:

Urinary Tract Infection (UTI) is a common cause of morbidity and mortality in older adults.

Objective:

To investigate antimicrobial resistance of uropathogenicEscherichia colifrom elderly patients in a General Hospital, Argentina.

Method:

During the period July 2011-July 2015, patients over 70 years old with urinary tract infections, without urinary catheters and with no antimicrobial therapy the previous week before sampling, were included. Phenotypic characterization was carried out.In vitroqualitative and quantitative antimicrobial resistances were investigated. Antimicrobials assayed: ampicillin, amoxicillin-clavulanate, cefazolin, cefuroxime, cefoxitin, cefotaxime, ceftazidime, cefepime, imipenem, ertapenem, gentamicin, nalidixic acid, ciprofloxacin, trimethoprim-sulfamethoxazole (TMS) and nitrofurantoin. Patients’ medical records were produced, and risk factors were analyzed by multivariate analysis.

Results:

768 bacterial isolates were identified asE. coli. Resistances to ampicillin (80.5%), nalidixic acid (61.7%), ciprofloxacin (42.8%), TMS (37.6%), amoxicillin-clavulanate (28.6%), cefazolin (21.6%), cefuroxime (20.7%), gentamicin (13.8%), cefotaxime (9.7%), ceftazidime (9.7%), cefepime (8.4%), cefoxitin (3.1%) and nitrofurantoin (2.3%) were observed. Resistance to carbapenems was not expressed. Production of extended spectrum β-lactamases was detected (7.6%) in community acquired (96%) and healthcare associated (4%) isolates. The independent risk factors for urinary infections produced by multi-resistantE. coliwere: diabetes mellitus, recurrent infections, hospitalization during the last year and exposure to β-lactams in the last 3 months.

Conclusion:

A high prevalence of resistance to β-lactams and to other antimicrobials was observed. Detection of antimicrobial multi-resistant isolates highlights the need of antimicrobial resistance surveillance in elderly patients with urinary tract infections.

Comparative characteristic of antimicrobial resistance in geriatric hospital: a retrospective cohort study

BACKGROUND AND AIMS

To examine antimicrobial resistance of commonly isolated pathogens in elderly hospitalized patients.

METHODS

Data regarding all clinically significant isolates from blood and urine cultures of patients admitted to a multilevel geriatric hospital during March 2015 to April 2016 were collected. Antimicrobial susceptibility testing was performed according to Clinical and Laboratory Standard Institute guidelines.

RESULTS

Escherichia coli, Proteus mirabilis, and Klebsiella pneumoniae were the most common isolates, with proportions of extended spectrum beta-lactamase positivity of 60, 40, and 61% respectively. Adjusted logistic regression models indicated that resistance of Escherichia coli to ceftriaxone [odds ratio (OR) 2.8, 95% confidence interval (CI) 1.5-5.1], ceftazidime (OR 2.8, 95% CI 1.5-5.1), ciprofloxacin (OR 2.2, 95% CI 1.2-4.0), amoxicillin/clavulanic acid (OR 2.3, 95% CI 1.2-4.3), and trimethoprim/sulfamethoxazole (OR 2.4, 95% CI 1.4-4.3) was significantly higher in skilled nursing wards than in acute geriatric wards. Resistance of Proteus mirabilis to ceftriaxone (OR 3.1, 95% CI 1.5-6.4) and Klebsiella pneumoniae to ciprofloxacin (OR 3.2, 95% CI 1.3-7.9) was significantly higher in skilled nursing wards than in acute wards.

CONCLUSIONS AND DISCUSSION

Antimicrobial resistance was found to be high in a multilevel geriatric hospital, especially in skilled nursing wards. These findings call for rethinking of the empirical antimicrobial therapy and of the efforts for prevention of nosocomial infection.

Isolation and characterization of a group of new Proteus bacteriophages

Four lytic Proteus bacteriophages, PM75, PM85, PM93, and PM116, which are active against multi-drug-resistant strains of P. mirabilis, were isolated from cattle and poultry samples. According to electron microscopy data, all of the investigated phages belonged to the family Podoviridae. They all demonstrated lytic activity against sensitive strains of P. mirabilis, and three of the phages, PM85, PM93, and PM116, are potential candidates for use in antibacterial treatment. The genomes and putative proteins of bacteriophages PM85, PM93, and PM116 were similar to those of Proteus phage vB_PmiP_Pm5460 [KP890822], and the investigated phages formed a distinct clade within the genus Sp6virus, subfamily Autographivirinae. The genome sequence of phage PM75 was similar to that of a previously described Proteus phage, PM16 [KF319020], and both of them demonstrated low nucleotide sequence identity to the genomes of the other most similar phages, namely, Vibrio phage VP93, Pantoea phage LIMElight, and KP34-like bacteriophages. According to cluster analysis of the complete genome sequences and phylogenetic analysis of the proteins essential for their life cycle, phages PM75 and PM16 are distinct from other similar phages from the phiKMV supergroup and should be recognized as constituting a new genus, "Pm16virus", within the subfamily Autographivirinae.

The Potential Virulence Factors of Providencia stuartii: Motility, Adherence, and Invasion

Providencia stuartii is the most common Providencia species capable of causing human infections. Currently P. stuartii is involved in high incidence of urinary tract infections in catheterized patients. The ability of bacteria to swarm on semisolid (viscous) surfaces and adhere to and invade host cells determines the specificity of the disease pathogenesis and its therapy. In the present study we demonstrated morphological changes of P. stuartii NK cells during migration on the viscous medium and discussed adhesive and invasive properties utilizing the HeLa-M cell line as a host model. To visualize the interaction of P. stuartii NK bacterial cells with eukaryotic cells in vitro scanning electron and confocal microscopy were performed. We found that bacteria P. stuartii NK are able to adhere to and invade HeLa-M epithelial cells and these properties depend on the age of bacterial culture. Also, to invade the host cells the infectious dose of the bacteria is essential. The microphotographs indicate that after incubation of bacterial P. stuartii NK cells together with epithelial cells the bacterial cells both were adhered onto and invaded into the host cells.

Antimicrobial Stewardship in the Post-Acute Long-Term Care Setting: Case Discussion and Updates

Improving the use of antimicrobial medications in the post-acute long-term care setting is critical for combating resistance and reducing adverse events in older adults. Antimicrobial stewardship refers to a set of commitments and actions designed to optimize the treatment of infectious diseases while minimizing the adverse effects associated with antimicrobial medication use. The Centers for Disease Control and Prevention recommend all nursing homes take steps to improve antimicrobial prescribing practices and reduce inappropriate use. The current article highlights initiatives and clinical considerations through a case discussion. [Journal of Gerontological Nursing, 42 (7), 10-14.].

Urinary tract infections in the geriatric patients

Objective

Urinary tract infections (UTI) are the second most common infection in geriatric population. This study investigated clinical findings, diagnostic approaches, complicating factors, prognosis, causative microorganisms and antimicrobial susceptibility in geriatric patients diagnosed with UTI.

Methods

A total of 140 hospitalised patients with UTIs were evaluated within three years between January 2011-January 2015 at the Eskisehir Yunus Emre State Hospital. UTI diagnosed when there were systemic and urinary signs and symptoms and a positive dipstick test and urine culture result, leukocyte and CRP like serum parameters.

Results

Among the studied patients, 41.4% had urological diseases, 20.7% had diabetes mellitus and 19.2% had neurological diseases. The most common symptoms and signs were fever, dysuria nausea/vomiting, general condition impairment, pyuria, haematuria. The laboratory values for CRP, ESR and leukocyte count were 84 mg/dL, 56 mm/s and 11.9 (10^3μL), with mean values being determined. Among patients having a urinary catheter (17.1%), 27.9% had a history of UTI, while 29.3% had been hospitalised. Escherichia coli and Klebsiella pneumoniae were the most commonly identified microorganisms. The mean duration for hospitalisation was 7.6 days, while a 5% mortality rate was observed over the course of the disease.

Conclusion

Because of the potential for serious complications and mortality, elderly patients with urinary tract infection, should receive immediate empirical treatment based on anamnesis, clinical evaluation and urinalysis and should be re-examined using results from cultures and antibiograms upon follow-up.

Bacterial epidemiology and antimicrobial resistance profiles of urinary specimens of the elderly

OBJECTIVE

Although urinary tract infections are the second leading cause of infections among patients aged above 65 years, data on bacterial epidemiology of urinary specimens in these patients is scarce. Our aim was to describe the main bacterial species found at significant levels in urine specimens of the elderly and to determine their antimicrobial resistance profiles.

METHODS

From October 2012 to October 2015, all urinary specimens (catheter-related or not) received at the laboratory of microbiology of the university hospital of Caen (France) were retrospectively studied. Results were compared to those of urinary specimens of patients aged 18-64 years. Bacterial identification was performed using MALDI-TOF mass spectrometry and antimicrobial susceptibility testing was performed as per CA-SFM guidelines.

RESULTS

Out of 33,302 urine cytobacteriological examinations (UCBE) performed in patients aged above 65 years, 13,450 microorganisms were identified. Escherichia coli was the most frequent species (41.8%) followed by Enterococcus faecalis (9.7%), Pseudomonas aeruginosa (5.7%), Proteus mirabilis (4.6%), and Klebsiella pneumoniae (4.2%). Around 9% of E. coli isolates were resistant to third-generation cephalosporins, including 8.2% by production of extended-spectrum β-lactamase (ESBL). This prevalence was significantly higher than that observed in urinary specimens of patients aged 18-74 years (4.9%, P<0.001).

CONCLUSION

The bacterial epidemiology of urines collected from the elderly is diverse and significantly different from that of urine specimens of younger patients, with a higher proportion of multidrug-resistant bacteria (particularly ESBL-producing E. coli).

Providencia stuartii form biofilms and floating communities of cells that display high resistance to environmental insults

Biofilms are organized communities of bacterial cells that are responsible for the majority of human chronic bacterial infections. Providencia stuartii is a Gram-negative biofilm-forming bacterium involved in high incidence of urinary tract infections in catheterized patients. Yet, the structuration of these biofilms, and their resistance to environmental insults remain poorly understood. Here, we report on planktonic cell growth and biofilm formation by P. stuartii, in conditions that mimic its most common pathophysiological habitat in humans, i.e. the urinary tract. We observed that, in the planktonic state, P. stuartii forms floating communities of cells, prior to attachment to a surface and subsequent adoption of the biofilm phenotype. P. stuartii planktonic and biofilm cells are remarkably resistant to calcium, magnesium and to high concentrations of urea, and show the ability to grow over a wide range of pHs. Experiments conducted on a P. stuartii strain knocked-out for the Omp-Pst2 porin sheds light on the role it plays in the early stages of growth, as well as in the adaptation to high concentration of urea and to varying pH.

Sepsis and Other Infectious Disease Emergencies in the Elderly

Waning immunity and declining anatomic and physiologic defenses render the elder vulnerable to a wide range of infectious diseases. Clinical presentations are often atypical and muted, favoring global changes in mental status and function over febrile responses or localizing symptoms. This review encompasses early recognition, evaluation, and appropriate management of these common infections specifically in the context of elders presenting to the emergency department. With enhanced understanding and appreciation of the unique aspects of infections in the elderly, emergency physicians can play an integral part in reducing the morbidity and mortality associated with these often debilitating and life-threatening diseases.

Lytic bacteriophage PM16 specific for Proteus mirabilis: a novel member of the genus Phikmvvirus

Lytic Proteus phage PM16, isolated from human faeces, is a novel virus that is specific for Proteus mirabilis cells. Bacteriophage PM16 is characterized by high stability, a short latency period, large burst size and the occurrence of low phage resistance. Phage PM16 was classified as a member of the genus Phikmvvirus on the basis of genome organization, gene synteny, and protein sequences similarities. Within the genus Phikmvvirus, phage PM16 is grouped with Vibrio phage VP93, Pantoea phage LIMElight, Acinetobacter phage Petty, Enterobacter phage phiKDA1, and KP34-like bacteriophages. An investigation of the phage-cell interaction demonstrated that phage PM16 attached to the cell surface, not to the bacterial flagella. The study of P. mirabilis mutant cells obtained during the phage-resistant bacterial cell assay that were resistant to phage PM16 re-infection revealed a non-swarming phenotype, changes in membrane characteristics, and the absence of flagella. Presumably, the resistance of non-swarming P. mirabilis cells to phage PM16 re-infection is determined by changes in membrane macromolecular composition and is associated with the absence of flagella and a non-swarming phenotype.

Carriage of antimicrobial-resistant commensal bacteria in Dutch long-term-care facilities

OBJECTIVES

The objective of this study was to assess carriage of antimicrobial-resistant commensal microorganisms, i.e. Escherichia coli and Staphylococcus aureus, and its predictors in long-term-care facilities (LTCFs).

METHODS

Nasal swabs and/or urine or incontinence samples were collected from participating residents in 111 LTCFs and tested for the presence of S. aureus and/or E. coli, respectively. Antimicrobial resistance to eight antimicrobials was linked to antimicrobial usage in the year preceding sampling and to LTCF characteristics. Using multilevel logistic regression, predictors of carriage of ESBL-producing E. coli in LTCFs were identified.

RESULTS

S. aureus was identified in 1269/4763 (26.6%) nasal swabs, including 13/4763 (0.3%) MRSA carriers in 9/107 (8%) LTCFs. Of the 5359 urine/incontinence samples, 2934 (55%) yielded E. coli, including 123 (4.2%) producing ESBL, which were found in 53/107 locations (range 1%-33%). For all but one antimicrobial (i.e. nitrofurantoin) >20% of isolated E. coli were resistant. Multilevel multivariable logistic regression identified two predictors of carriage of ESBL-producing E. coli: (i) antimicrobial usage (OR 1.8, 95% CI 1.1-3.0 for each extra 50 DDD/1000 residents/day); and (ii) presence of MRSA carriers in the LTCFs (OR 2.4, 95% CI 1.0-5.6).

CONCLUSIONS

The low proportion of 4.2% ESBL-producing E. coli and the low prevalence of 0.3% MRSA carriage found in LTCF residents suggest that Dutch LTCFs are not yet an important reservoir of MDR potential pathogens. Nevertheless, the large variation between LTCFs warrants close monitoring of antimicrobial resistance in LTCFs. Integrated surveillance, i.e. linking data sources on antimicrobial usage, microbiological testing, clinical background data and epidemiological data, is needed.

Global Emergence and Dissemination of Enterococci as Nosocomial Pathogens: Attack of the Clones?

Enterococci are Gram-positive bacteria that are found in plants, soil and as commensals of the gastrointestinal tract of humans, mammals, and insects. Despite their commensal nature, they have also become globally important nosocomial pathogens. Within the genus Enterococcus, Enterococcus faecium, and Enterococcus faecalis are clinically most relevant. In this review, we will discuss how E. faecium and E. faecalis have evolved to become a globally disseminated nosocomial pathogen. E. faecium has a defined sub-population that is associated with hospitalized patients and is rarely encountered in community settings. These hospital-associated clones are characterized by the acquisition of adaptive genetic elements, including genes involved in metabolism, biofilm formation, and antibiotic resistance. In contrast to E. faecium, clones of E. faecalis isolated from hospitalized patients, including strains causing clinical infections, are not exclusively found in hospitals but are also present in healthy individuals and animals. This observation suggests that the division between commensals and hospital-adapted lineages is less clear for E. faecalis than for E. faecium. In addition, genes that are reported to be associated with virulence of E. faecalis are often not unique to clinical isolates, but are also found in strains that originate from commensal niches. As a reflection of more ancient association of E. faecalis with different hosts, these determinants Thus, they may not represent genuine virulence genes but may act as host-adaptive functions that are useful in a variety of intestinal environments. The scope of the review is to summarize recent trends in the emergence of antibiotic resistance and explore recent developments in the molecular epidemiology, population structure and mechanisms of adaptation of E. faecium and E. faecalis.

Colonization with Multi-Drug Resistant Organisms in Nursing Homes: Scope, Importance, and Management

Bacterial infections are among the most common causes of morbidity and mortality in Nursing Homes (NH) and other long term care facilities. Multi-drug resistant organisms (MDROs) represent an ever-increasing share of causative agents of infection, and their prevalence in NHs is now just as high as in acute-care facilities, or even higher. Indeed, NHs are now considered a major reservoir of MDROs for the community at large. Asymptomatic colonization is usually a prerequisite to development of symptomatic infection. While progress has been made in defining epidemiology of MDROs in NHs, few studies have evaluated the role of changing healthcare delivery in introducing and further transmitting MDROs in this setting. Furthermore, the factors influencing the spread of colonization and the key prognostic indicators leading to symptomatic infections in the burgeoning short stay population need to be explored further. The difficulty of this task lies in the heterogeneity of NHs in terms of focus of care, organization and resources, and on the diversity among the many MDRO species encountered, which harbor different resistance genes and with a different prevalence depending on the geographic location, local antimicrobial pressure and residents risk factors such as use of indwelling devices, functional disability, wounds and other comorbidities. We present literature findings on the scope and importance of colonization as a pathway to infection with MDROs in NHs, underline important open questions that need further research, and discuss the strength of the evidence for current and proposed screening, prevention, and management interventions.

Influence of flocculating agents and structural vehicles on the physical stability and rheological behavior of nitrofurantoin suspension

Background:

Nitrofurantoin is a nitrofuran antibiotic that has been used for treatment of urinary tract against positive and negative bacteria.

Objectives:

The aim of this study was to evaluate the effect of structural vehicles and flocculating agents on physical stability and rheological behavior of nitrofurantoin suspension.

Materials and Methods:

To formulate the suspensions, the effect of glycerin and polysorbate 80 as wetting agents was evaluated and their particle sizes were determined using the sieve method. Then to achieve controlled flocculation, sodium citrate and aluminum chloride were added. After choosing the suitable wetting and flocculating agents, structural vehicles such as sodium carboxyl methyl cellulose and Veegum were evaluated individually and in combination. In addition, the effect of sorbitol on density of continuous phase and some physical stability parameters such as sedimentation volume, degree of flocculation and ease of redispersion of the suspensions were evaluated. After incorporation of structural vehicles, the rheological properties of formulations were also determined to find their flow behavior.

Results:

According to the results, glycerin (0.2%) and sodium citrate (0.3%) had the best effect on the suspension stability as wetting and flocculating agents, respectively. Rheological properties of formulations showed pseudoplastic behavior with some degree of thixotropy.

Conclusions:

In conclusion, the suspension containing Veegum 1%, sodium carboxy methyl cellulose 1%, glycerine 0.2%, sodium citrate 0.3% and sorbitol 20 % was chosen as the most physically stable formulation.