What have we learned about antimicrobial use and the risks for Clostridium difficile-associated diarrhoea?

Impact of the COVID-19 pandemic on Clostridioides difficile infection in a tertiary healthcare institution in Belgium

OBJECTIVES

Clostridioides difficile infection (CDI) causes the greatest number of healthcare-associated infectious diarrhoea. CDIs are transmitted by direct and indirect patient-to-patient contact and risk increases with the use of antibiotics. Since early 2020, the COVID-19 pandemic has affected healthcare systems in many ways including substantial changes in hygiene behaviour. The aim of this study was to assess whether CDI incidence differed during the COVID-19 pandemic compared to a year before.

METHODS

All tests for suspected CDI cases were recorded for a hospital in Brussels, Belgium. The percentage of CDI-positive results and incidences (total and healthcare-associated (HA)-CDI)) for years 2019, 2020, 2021, and 2022 were calculated. Antibiotic consumption was analysed for years 2019 and 2020.

RESULTS

Since the COVID-19 pandemic struck, a significant reduction of up to 39% was observed in the number of Clostridioides difficile stool tests in our hospital. A significant decrease in the percentage of positive tests and a 50% decrease in the incidence of CDI (total and HA-CDI) was found for 2020 compared with 2019 and confirmed for years 2021 and 2022. The decrease in CDI incidence was mostly marked in haematology, nephrology, and gastroenterology units. No significant change in the use of antibiotics was found.

CONCLUSION

The global decrease in CDI incidence observed in our hospital was not associated with a change in the use of antibiotics. The control measures implemented to prevent COVID-19 transmission may explain a reduction in CDI incidence. An underdiagnosis of CDI cannot be excluded.

Real-World Data in Pharmacovigilance Database Provides a New Perspective for Understanding the Risk of Clostridium difficile Infection Associated with Antibacterial Drug Exposure

Antibacterial drug exposure (ADE) is a well-known potential risk factor for Clostridium difficile infection (CDI), but it remains controversial which certain antibacterial drugs are associated with the highest risk of CDI occurrence. To summarize CDI risk associated with ADE, we reviewed the CDI reports related to ADE in the FDA Adverse Event Reporting System database and conducted disproportionality analysis to detect adverse reaction (ADR) signals of CDI for antibacterial drugs. A total of 8063 CDI reports associated with ADE were identified, which involved 73 antibacterial drugs. Metronidazole was the drug with the greatest number of reports, followed by vancomycin, ciprofloxacin, clindamycin and amoxicillin. In disproportionality analysis, metronidazole had the highest positive ADR signal strength, followed by vancomycin, cefpodoxime, ertapenem and clindamycin. Among the 73 antibacterial drugs, 58 showed at least one positive ADR signal, and ceftriaxone was the drug with the highest total number of positive signals. Our study provided a real-world overview of CDI risk for AED from a pharmacovigilance perspective and showed risk characteristics for different antibacterial drugs by integrating its positive-negative signal distribution. Meanwhile, our study showed that the CDI risk of metronidazole and vancomycin may be underestimated, and it deserves further attention and investigation.

Obstructing Ureteral Calculi and Presumed Infection: Impact of Antimicrobial Duration and Time From Decompression to Stone Treatment in Developing Urosepsis

OBJECTIVE

To determine whether the duration of antibiotic treatment and timing between urgent renal decompression and stone intervention impacts the risk of developing urosepsis following definitive stone treatment.

MATERIALS & METHODS

A retrospective review of patients who were diagnosed with obstructive urolithiasis and underwent urgent decompression with a ureteral double J stent or percutaneous nephrostomy at our institution between 2012 and 2018 was performed. We narrowed our analysis to the subset of patients who had suspected infection and received definitive stone treatment at our institution. Demographic, infection and antimicrobial data, and initial admission to stone treatment characteristics were collected. Factors associated with developing urosepsis were analyzed.

RESULTS

We identified 872 patients who were treated with urgent renal decompression, of which 215 were analyzed that had suspected infection and also received definitive stone removal at our institution. Thirty-three had fevers, 64.2% had a positive urine culture, and 45.6% had urosepsis at the initial presentation. The median antibiotics duration post decompression was 13 days (IQR 8-18). The median duration from decompression to stone treatment was 17 days (IQR 12-27). Of all, 4.6% of the patients developed urosepsis post ureteroscopy and 5% post percutaneous nephrolithotomy. No factors were associated with developing urosepsis post stone treatment on logistic regression analyses.

CONCLUSION

In patients requiring urgent decompression for obstructing urolithiasis and suspected infection, the time between decompression and stone treatment and the length of antibiotic exposure did not impact rates of postoperative urosepsis. This highlights the importance of maintaining high clinical suspicion for prolonged use of antibiotics, to prevent overtreatment and possible exacerbation of antibiotic resistance.

Nanotechnology: a contemporary therapeutic approach in combating infections from multidrug-resistant bacteria

In the 20th century, the discovery of antibiotics played an essential role in the fight against infectious diseases, including meningitis, typhoid fever, pneumonia and Mycobacterium tuberculosis. The development of multidrug resistance in microflora due to improper antibiotic use created significant public health issues. Antibiotic resistance has increased at an alarming rate in the past few decades. Multidrug-resistant bacteria (superbugs) such as methicillin-resistant Staphylococcus aureus (MRSA) as well as drug-resistant tuberculosis pose serious health implications. Despite the continuous increase in resistant microbes, the discovery of novel antibiotics is constrained by the cost and complexities of discovery of drugs. The nanotechnology has given new hope in combating this problem. In the present review, recent developments in therapeutics utilizing nanotechnology for novel antimicrobial drug development are discussed. The nanoparticles of silver, gold and zinc oxide have proved to be efficient antimicrobial agents against multidrug-resistant Klebsiella, Pseudomonas, Escherichia Coli and MRSA. Using nanostructures as carriers for antimicrobial agents provides better bioavailability, less chances of sub-therapeutic drug accumulation and less drug-related toxicity. Nanophotothermal therapy using fullerene and antibody functionalized nanostructures are other strategies that can prove to be helpful.

Clostridioides difficile-induced diarrhoea following dasatinib therapy

Dasatinib, an oral tyrosine kinase inhibitor, is approved for therapy of chronic myeloid leukaemia (CML). Common adverse effects of this therapy include myelosuppression, fluid retention and diarrhoea. However, Clostridioides difficile infections (CDIs) in the context of dasatinib therapy, without a history of antecedent antibiotic use, has not been reported previously. We present here a case of a 36-year-old man diagnosed with accelerated phase of CML, who was started on treatment with dasatinib. Two months into therapy, he experienced profuse diarrhoea and abdominal pain. Colonoscopy revealed multiple confluent colonic mucosal ulcerations. Immunoassay study of stool revealed positive C. difficile toxin. The patient was started on oral metronidazole, with discontinuation of all other drugs, including dasatinib. He made a complete uneventful recovery following 2 weeks of antibiotic therapy. Chemotherapeutic agents, such as dasatinib, should be considered as possible etiological agents in the pathogenesis of CDI, even in absence of antibiotic use.

Short-course therapy for diarrhea-predominant irritable bowel syndrome: understanding the mechanism, impact on gut microbiota, and safety and tolerability of rifaximin

Irritable bowel syndrome (IBS) is a common gastrointestinal (GI) disorder characterized by abdominal pain that occurs with defecation or alterations in bowel habits. Further classification is based on the predominant bowel habit: constipation-predominant IBS, diarrhea-predominant IBS (IBS-D), or mixed IBS. The pathogenesis of IBS is unclear and is considered multifactorial in nature. GI dysbiosis, thought to play a role in IBS pathophysiology, has been observed in patients with IBS. Alterations in the gut microbiota are observed in patients with small intestinal bacterial overgrowth, and overgrowth may occur in a subset of patients with IBS. The management of IBS includes therapies targeting the putative factors involved in the pathogenesis of the condition. However, many of these interventions (eg, eluxadoline and alosetron) require long-term, daily administration and have important safety considerations. Agents thought to modulate the gut microbiota (eg, antibiotics and probiotics) have shown potential benefits in clinical studies. However, conventional antibiotics (eg, neomycin) are associated with several adverse events and/or the risk of bacterial antibiotic resistance, and probiotics lack uniformity in composition and consistency of response in patients. Rifaximin, a nonsystemic antibiotic administered as a 2-week course of therapy, has been shown to be safe and efficacious for the treatment of IBS-D. Rifaximin exhibits a favorable benefit-to-harm ratio when compared with daily therapies for IBS-D (eg, alosetron and tricyclic antidepressants), and rifaximin was not associated with the emergence of bacterial antibiotic resistance. Thus, short-course therapy with rifaximin is an appropriate treatment option for IBS-D.

Prolonged Mechanical Ventilation Assistance Interacts Synergistically with Carbapenem for Clostridium difficile Infection in Critically Ill Patients

Objectives: Interactions between mechanical ventilation (MV) and carbapenem interventions were investigated for the risk of Clostridium difficile infection (CDI) in critically ill patients undergoing concurrent carbapenem therapy. Methods: Taiwan’s National Intensive Care Unit Database (NICUD) was used in this analytical, observational, and retrospective study. We analyzed 267,871 intubated patients in subgroups based on the duration of MV support: 7–14 days (n = 97,525), 15–21 days (n = 52,068), 22–28 days (n = 35,264), and 29–60 days (n = 70,021). The primary outcome was CDI. Results: Age (>75 years old), prolonged MV assistance (>21 days), carbapenem therapy (>15 days), and high comorbidity scores were identified as independent risk factors for developing CDI. CDI risk increased with longer MV support. The highest rate of CDI was in the MV 29–60 days subgroup (adjusted hazard ratio (AHR) = 2.85; 95% confidence interval (CI) = 1.46–5.58; p < 0.02). Moreover, higher CDI rates correlated with the interaction between MV and carbapenem interventions; these CDI risks were increased in the MV 15–21 days (AHR = 2.58; 95% CI = 1.12–5.91) and MV 29–60 days (AHR = 4.63; 95% CI = 1.14–10.03) subgroups than in the non-MV and non-carbapenem subgroups. Conclusions: Both MV support and carbapenem interventions significantly increase the risk that critically ill patients will develop CDI. Moreover, prolonged MV support and carbapenem therapy synergistically induce CDI. These findings provide new insights into the role of MV support in the development of CDI.

Fecal microbiota transplantation in the treatment of Clostridium difficile infection: state of the art and literature review

ABSTRACT Clostridium difficile infection is a common complication following intestinal dysbiosis caused by abusive antibiotic use. It presents medical importance due to the high rates of recurrence and morbidity. Fecal microbiota transplantation is an effective alternative for the treatment of recurrent and refractory C. difficile infection and consists of introducing the intestinal microbiota from a healthy donor into a patient with this infection. The exact physiological mechanism by which fecal microbiota transplantation alters the intestinal microbiota is not well established, but it is clear that it restores the diversity and structure of the microbiota by promoting increased resistance to colonization by C. difficile. Several routes of transplant administration are being studied and used according to the advantages presented. All forms of application had a high cure rate, and the colonoscopic route was the most used. No relevant complications and adverse events have been documented, and the cost-effectiveness over conventional treatment has proven advantageous. Despite its efficacy, it is not commonly used as initial therapy, and more studies are needed to establish this therapy as the first option in case of refractory and recurrent Clostridium difficileinfection.

Clostridium difficile infection in hospitalized octogenarian patients

AIM

To evaluate the risk factors and outcome of Clostridium difficile infection in hospitalized octogenarian patients.

METHODS

A retrospective analysis of risk factors and outcome of C. difficile infection in hospitalized octogenarians was carried out at two academic centers in Romania from January 2014 to September 2016. Demographic, clinical and laboratory characteristics; antibiotics and proton pump inhibitors use in-hospital and 2 months before admission; comorbidities; length of hospital stay; treatment; and outcome were carefully collected from the patients' medical charts and compared with those from octogenarians hospitalized during the same period.

RESULTS

A total of 286 octogenarians were hospitalized during the study period and among them 79 (27.6%) were diagnosed with C. difficile infection. On multivariate logistic regression analyses, the previous 2 months' hospitalizations (OR 10.231, 95% CI 1.769-58.965, P = 0.009), antibiotic use 2 months before admission (OR 12.596, 95% CI 1.024-15.494, P = 0.048), antibiotic treatment during hospitalization (OR 6.302, 95% CI 3.510-11.316, P < 0.0001), arterial hypertension (OR 11.228, 95% CI 1.917-65.783, P = 0.007), chronic kidney disease (OR 4.474, 95% CI 1.037-19.299, P = 0.045) and chronic cardiac failure (OR 7.328, 95% CI 2.068-25.967, P = 0.002) were independently associated with infection. Patients with infection had longer length of hospital stay than those without (15.3 ± 5.1 vs 11.1 ± 4.3 days, P < 0.0001). None of the patients with infection had severe disease, none required surgery and none died during hospitalization.

CONCLUSIONS

Hospitalized octogenarians with comorbidities, recently hospitalized or receiving antibiotic treatment are at risk for C. difficile infection. Clinicians evaluating such patients should have a high index of suspicion for this infection. Geriatr Gerontol Int 2018; 18: 315-320.

Modulation of the gut microbiota: a focus on treatments for irritable bowel syndrome

Irritable bowel syndrome (IBS), which is characterized by recurrent abdominal pain and disordered bowel habits, is one of the most common functional bowel disorders. IBS is a substantial burden on both patient health-related quality of life and healthcare costs. Several pathophysiologic mechanisms have been postulated for the occurrence of IBS, including altered gastrointestinal motility, visceral hypersensitivity, changes in gut permeability, immune activation, gut-brain dysregulation, central nervous system dysfunction, and changes in the gut microbiota. Of note, both qualitative and quantitative differences have been observed in the gut microbiota of a population with IBS versus a healthy population. Because of the substantial interest in the gut microbiota and its role as a therapeutic target in IBS, this article provides an overview of specific interventions with the potential to modulate the gut microbiota in IBS, including elimination diets, prebiotics, probiotics, synbiotics, and nonsystemic antibiotics. Although probiotics and synbiotics are generally well tolerated, differences in the composition and concentration of different bacterial species and inclusion or exclusion of prebiotic components varies widely across studies and has prevented strong recommendations on their use in IBS. For nonsystemic antibiotics, rifaximin is indicated in the United States for the treatment of IBS with diarrhea in adults and has been shown to be efficacious and well tolerated in well-designed clinical trials. Overall, more consistent evidence is needed regarding the efficacy and safety of elimination diets, prebiotics, probiotics, and synbiotics for the treatment of patients with IBS. Furthermore, additional well-designed studies are needed that examine alterations in the gut microbiota that occur with these interventions and their potential associations with clinical symptoms of IBS.

Molecular epidemiology of Clostridium difficile infection in a Brazilian cancer hospital

Clostridium difficile is a Gram-positive spore forming anaerobic bacterium and the main cause of healthcare-associated diarrhea. This study aimed to perform the phenotypic characterization and molecular typing of Clostridium difficile isolates among patients at a cancer hospital in Brazil. During 18 months, 48 diarrheic fecal samples were collected, of these 48% were positive in either one or both of the performed tests: detection of toxins A/B and culture. Clostridium difficile was recovered from four samples (17%). All strains carried toxin A and B genes, and the isolates belonged to PCR-ribotype 014/020, PGFE-type NAP4 and toxinotype XVIII. On the other hand, one isolate belonged to a novel PCR-ribotype, and PFGE-type, likewise to toxinotype IXb. The isolates showed susceptibility to metronidazole, vancomycin and moxifloxacin, and were resistant to ciprofloxacin. Finally, the findings indicate high positivity between the samples tested, suggesting an expressive importance of this infection, including detection of a novel ribotype/PFGE-type of Clostridium difficile, and show for the first time the detection of community-associated Clostridium difficile infection (CA-CDI) in these patients in Northeast Brazil. These data emphasize the importance to a better understanding of the epidemiological situation of this infection in Brazilian hospitals.

Surgical prophylaxis with gentamicin and acute kidney injury: a systematic review and meta-analysis

BACKGROUND

Gentamicin has been increasingly used instead of cephalosporins for surgical prophylaxis in an attempt to reduce the rate of "Clostridium difficile" infection. There are limited data regarding nephrotoxicity related to gentamicin in these patients.

METHODS

We have conducted a systematic review and meta-analysis to evaluate the risk of acute kidney injury (AKI) in gentamicin-containing surgical prophylactic regimens, compared to regimens without gentamicin, in several types of surgery. Electronic searches were performed using PubMed and Embase, including terms for "AKI, gentamicin, and surgical prophylaxis" with and without MeSH/EMTREE functions. Statistical analysis was then performed using a random-effect model; risk ratios (RR), risk differences (RD) and heterogeneity (I²) were calculated. Funnel plot was used for assessment of publication bias.

RESULTS

Eleven studies with fifteen cohorts with 18,354 patients were included in the analysis. Subgroup analysis was performed according to surgery type. We have found that antibiotic prophylaxis with gentamicin containing regimen has significant risk for developing postoperative AKI in orthopedic surgery (RR 2.99; 95% CI: 1.84, 4.88). The results were inconclusive in other types of surgery. Funnel plot indicates potential publication bias.

CONCLUSIONS

Gentamicin-induced AKI is significant in patients undergoing orthopedic surgery. Physicians should consider risks and benefits of using this regimen in individual patients.

Repeat Rifaximin for Irritable Bowel Syndrome: No Clinically Significant Changes in Stool Microbial Antibiotic Sensitivity

BACKGROUND

Rifaximin has demonstrated efficacy and safety for diarrhea-predominant irritable bowel syndrome (IBS-D).

AIM

To determine the rifaximin repeat treatment effect on fecal bacterial antibiotic susceptibility.

METHODS

Patients with IBS in Trial 3 (TARGET 3) study who responded to open-label rifaximin 550 mg three times daily for 2 weeks, with symptom recurrence within 18 weeks, were randomized to double-blind treatment: two 2-week repeat courses of rifaximin or placebo, separated by 10 weeks. Prospective stool sample collection occurred before and after open-label rifaximin, before and after the first repeat course, and at the end of the study. Susceptibility testing was performed with 11 antibiotics, including rifaximin and rifampin, using broth microdilution or agar dilution methods.

RESULTS

Of 103 patients receiving open-label rifaximin, 73 received double-blind rifaximin (n = 37) or placebo (n = 36). A total of 1429 bacterial and yeast isolates were identified, of which Bacteroidaceae (36.7%) and Enterobacteriaceae (33.9%) were the most common. In the double-blind phase, Clostridium difficile was highly susceptible to rifaximin [minimum inhibitory concentration (MIC) range 0.008-1 µg/mL] and rifampin (MIC range 0.004-0.25 µg/mL). Following double-blind rifaximin treatment, Staphylococcus isolates remained susceptible to rifaximin at all visits (MIC₅₀ range ≤0.06-32 µg/mL). Rifaximin exposure was not associated with long-term cross-resistance of Bacteroidaceae, Enterobacteriaceae, and Enterococcaceae to rifampin or nonrifamycin antibiotics tested.

CONCLUSIONS

In this study, short-term repeat treatment with rifaximin has no apparent long-term effect on stool microbial susceptibility to rifaximin, rifampin, and nonrifamycin antibiotics. CLINICALTRIALS.

GOV IDENTIFIER

NCT01543178.

Predicting the Risk of Clostridium difficile Infection upon Admission: A Score to Identify Patients for Antimicrobial Stewardship Efforts

INTRODUCTION

Increasing morbidity and health care costs related to Clostridium difficile infection (CDI) have heightened interest in methods to identify patients who would most benefit from interventions to mitigate the likelihood of CDI.

OBJECTIVE

To develop a risk score that can be calculated upon hospital admission and used by antimicrobial stewards, including pharmacists and clinicians, to identify patients at risk for CDI who would benefit from enhanced antibiotic review and patient education.

METHODS

We assembled a cohort of Kaiser Permanente Northwest patients with a hospital admission from July 1, 2005, through December 30, 2012, and identified CDI in the six months following hospital admission. Using Cox regression, we constructed a score to identify patients at high risk for CDI on the basis of preadmission characteristics. We calculated and plotted the observed six-month CDI risk for each decile of predicted risk.

RESULTS

We identified 721 CDIs following 54,186 hospital admissions-a 6-month incidence of 13.3 CDIs/1000 patient admissions. Patients with the highest predicted risk of CDI had an observed incidence of 53 CDIs/1000 patient admissions. The score differentiated between patients who do and do not develop CDI, with values for the extended C-statistic of 0.75. Predicted risk for CDI agreed closely with observed risk.

CONCLUSION

Our risk score accurately predicted six-month risk for CDI using preadmission characteristics. Accurate predictions among the highest-risk patient subgroups allow for the identification of patients who could be targeted for and who would likely benefit from review of inpatient antibiotic use or enhanced educational efforts at the time of discharge planning.

Novel Clostridium difficile Anti-Toxin (TcdA and TcdB) Humanized Monoclonal Antibodies Demonstrate In Vitro Neutralization across a Broad Spectrum of Clinical Strains and In Vivo Potency in a Hamster Spore Challenge Model

Clostridium difficile (C. difficile) infection (CDI) is the main cause of nosocomial antibiotic-associated colitis and increased incidence of community-associated diarrhea in industrialized countries. At present, the primary treatment of CDI is antibiotic administration, which is effective but often associated with recurrence, especially in the elderly. Pathogenic strains produce enterotoxin, toxin A (TcdA), and cytotoxin, toxin B (TcdB), which are necessary for C. difficile induced diarrhea and gut pathological changes. Administration of anti-toxin antibodies provides an alternative approach to treat CDI, and has shown promising results in preclinical and clinical studies. In the current study, several humanized anti-TcdA and anti-TcdB monoclonal antibodies were generated and their protective potency was characterized in a hamster infection model. The humanized anti-TcdA (CANmAbA4) and anti-TcdB (CANmAbB4 and CANmAbB1) antibodies showed broad spectrum in vitro neutralization of toxins from clinical strains and neutralization in a mouse toxin challenge model. Moreover, co-administration of humanized antibodies (CANmAbA4 and CANmAbB4 cocktail) provided a high level of protection in a dose dependent manner (85% versus 57% survival at day 22 for 50 mg/kg and 20 mg/kg doses, respectively) in a hamster gastrointestinal infection (GI) model. This study describes the protective effects conferred by novel neutralizing anti-toxin monoclonal antibodies against C. difficile toxins and their potential as therapeutic agents in treating CDI.

Predicting the risk of Clostridium difficile infection following an outpatient visit: development and external validation of a pragmatic, prognostic risk score

Increasing morbidity related to Clostridium difficile infection (CDI) has heightened interest in the identification of patients who would most benefit from recognition of risk and intervention. We sought to develop and validate a prognostic risk score to predict CDI risk for individual patients following an outpatient healthcare visit. We assembled a cohort of Kaiser Permanente Northwest (KPNW) patients with an index outpatient visit between 2005 and 2008, and identified CDI in the year following that visit. Applying Cox regression, we synthesized a priori predictors into a CDI risk score, which we validated among a Kaiser Permanente Colorado (KPCO) cohort. We calculated and plotted the observed 1-year CDI risk for each decile of predicted risk for both cohorts. Among 356 920 KPNW patients, 608 experienced CDI, giving a 1-year incidence of 2.2 CDIs per 1000 patients. The Cox model differentiated between patients who do and do not develop CDI: there was a C-statistic of 0.83 for KPNW. The simpler points-based risk score, derived from the Cox model, was validated successfully among 296 550 KPCO patients, with no decline in the area under the receiver operating characteristic curve: 0.785 (KPNW) vs. 0.790 (KPCO). The predicted risk for CDI agreed closely with the observed risk. Our CDI risk score utilized data collected during usual care to successfully identify patients who developed CDI, discriminating them from patients at the lowest risk for CDI. Our prognostic CDI risk score provides a decision-making tool for clinicians in the outpatient setting.

Clostridium difficile Infection: Clinical Challenges and Management Strategies

Clostridium difficile has become the leading cause of nosocomial diarrhea in adults. A substantial increase has occurred in morbidity and mortality associated with disease caused by C difficile and in the identification of new hypervirulent strains, warranting a high clinical index of suspicion for infections due to this organism. Prevention of infection requires a multidisciplinary approach, including early recognition of disease, effective contact isolation precautions, adherence to disinfectant policies, and judicious use of antibiotics. Current treatment approaches are based on the severity of illness. As hypervirulent strains evolve, unsuccessful treatments are more common. Complicated colitis caused by C difficile may benefit from surgical intervention. Subtotal colectomy and end ileostomy have been the procedures of choice, but are associated with a high mortality rate because of late surgical consultation and use of surgery as a salvage therapy. A promising surgical alternative is creation of a diverting loop ileostomy with colonic lavage.

Ciprofloxacin Affects Host Cells by Suppressing Expression of the Endogenous Antimicrobial Peptides Cathelicidins and Beta-Defensin-3 in Colon Epithelia

Antibiotics exert several effects on host cells including regulation of immune components. Antimicrobial peptides (AMPs), e.g., cathelicidins and defensins display multiple functions in innate immunity. In colonic mucosa, cathelicidins are induced by butyrate, a bacterial fermentation product. Here, we investigated the effect of antibiotics on butyrate-induced expression of cathelicidins and beta-defensins in colon epithelial cells. Real-time PCR analysis revealed that ciprofloxacin and clindamycin reduce butyrate-induced transcription of the human cathelicidin LL-37 in the colonic epithelial cell line HT-29. Suppression of LL-37 peptide/protein by ciprofloxacin was confirmed by Western blot analysis. Immunohistochemical analysis demonstrated that ciprofloxacin suppresses the rabbit cathelicidin CAP-18 in rectal epithelia of healthy and butyrate-treated Shigella-infected rabbits. Ciprofloxacin also down-regulated butyrate-induced transcription of the human beta-defensin-3 in HT-29 cells. Microarray analysis of HT-29 cells revealed upregulation by butyrate with subsequent down-regulation by ciprofloxacin of additional genes encoding immune factors. Dephosphorylation of histone H3, an epigenetic event provided a possible mechanism of the suppressive effect of ciprofloxacin. Furthermore, LL-37 peptide inhibited Clostridium difficile growth in vitro. In conclusion, ciprofloxacin and clindamycin exert immunomodulatory function by down-regulating AMPs and other immune components in colonic epithelial cells. Suppression of AMPs may contribute to the overgrowth of C. difficile, causing antibiotic-associated diarrhea.

An optimized, synthetic DNA vaccine encoding the toxin A and toxin B receptor binding domains of Clostridium difficile induces protective antibody responses in vivo

Clostridium difficile-associated disease (CDAD) constitutes a large majority of nosocomial diarrhea cases in industrialized nations and is mediated by the effects of two secreted toxins, toxin A (TcdA) and toxin B (TcdB). Patients who develop strong antitoxin antibody responses can clear C. difficile infection and remain disease free. Key toxin-neutralizing epitopes have been found within the carboxy-terminal receptor binding domains (RBDs) of TcdA and TcdB, which has generated interest in developing the RBD as a viable vaccine target. While numerous platforms have been studied, very little data describes the potential of DNA vaccination against CDAD. Therefore, we created highly optimized plasmids encoding the RBDs from TcdA and TcdB in which any putative N-linked glycosylation sites were altered. Mice and nonhuman primates were immunized intramuscularly, followed by in vivo electroporation, and in these animal models, vaccination induced significant levels of both anti-RBD antibodies (blood and stool) and RBD-specific antibody-secreting cells. Further characterization revealed that sera from immunized mice and nonhuman primates could detect RBD protein from transfected cells, as well as neutralize purified toxins in an in vitro cytotoxicity assay. Mice that were immunized with plasmids or given nonhuman-primate sera were protected from a lethal challenge with purified TcdA and/or TcdB. Moreover, immunized mice were significantly protected when challenged with C. difficile spores from homologous (VPI 10463) and heterologous, epidemic (UK1) strains. These data demonstrate the robust immunogenicity and efficacy of a TcdA/B RBD-based DNA vaccine in preclinical models of acute toxin-associated and intragastric, spore-induced colonic disease.

Emerging role of probiotics and antimicrobials in the management of irritable bowel syndrome

OBJECTIVE

To review the potential role of probiotics and antimicrobials for management of functional bowel disorders (FBDs), with a focus on irritable bowel syndrome (IBS).

RESEARCH DESIGN AND METHODS

Relevant adult data were identified via PubMed, with additional references obtained by reviewing bibliographies from selected articles.

RESULTS

Probiotic treatment involves colonizing the intestines with beneficial microorganisms, whereas antimicrobial therapy involves modulation of the bacterial load and/or host response. A meta-analysis reported that all probiotic species evaluated improved flatulence compared with placebo; some, but not all, species improved abdominal pain and abdominal bloating/distension; and no species evaluated improved stool frequency or consistency, straining during stool evacuation, sense of incomplete evacuation, or fecal urgency. Two additional meta-analyses reported that probiotics significantly improved overall IBS symptoms. Individual studies have demonstrated potential benefits of probiotics for functional constipation symptoms. The nonsystemic antimicrobials neomycin and rifaximin have been evaluated in patients with IBS and other FBDs. Neomycin may improve global IBS symptoms and provide bowel normalization versus placebo, but the risk of ototoxicity and the development of clinically relevant bacterial resistance may limit its use for recurrent symptoms. In phase 3 randomized studies, rifaximin-treated patients were significantly more likely than placebo-treated patients to achieve adequate relief of global IBS symptoms and abdominal bloating. Although preliminary data suggest that development of clinically relevant bacterial resistance is unlikely with rifaximin, prospective data are needed, and a phase 3 study is ongoing. Limitations of evidence for probiotics include small populations analyzed and lack of clarity in optimal dosing regimen; antimicrobial evidence would benefit from better understanding of the effects of repeated treatment in patients with IBS.

CONCLUSIONS

Probiotics and nonsystemic antibiotics have a place in IBS management. Additional studies are needed to establish optimal regimens and identify subgroups of patients most likely to benefit from these therapies.

Efficacy and safety of moxifloxacin in hospitalized patients with secondary peritonitis: pooled analysis of four randomized phase III trials

BACKGROUND

Secondary peritonitis is an advanced form of complicated intra-abdominal infection (cIAI) requiring hospitalization, surgical source control, and empiric antibiotic therapy against causative aerobic and anaerobic bacteria.

METHODS

This pooled analysis of four prospective, active-controlled randomized clinical trials compared the efficacy and safety of moxifloxacin with that of comparator antibiotics in patients with confirmed secondary peritonitis. The primary efficacy endpoint was clinical success rate at test-of-cure (TOC) between day 10 and 45 post-therapy in the per-protocol (PP) population. Safety and clinical efficacy were assessed also in the intent-to-treat population (ITT). Bacteriological success was assessed at TOC in the microbiologically-valid population as a secondary efficacy endpoint.

RESULTS

Overall clinical success rates at TOC were 85.3% (431 of 505 patients) in the moxifloxacin and 88.4% (459 of 519 patients) in the comparator treatment groups (PP population, point estimate for the difference in success rates: -3.0%; 95% CI -7.06%, 1.05%), respectively. Similar clinical success rates between moxifloxacin and comparators were observed by anatomical site of infection, and ranged from 80.6% to 100% for moxifloxacin and from 71.4% to 96.6% for comparators, respectively. Bacteriologic success rates were similar with moxifloxacin (82.4%) and comparators (86.8%), respectively. The proportion of patients experiencing any treatment-emergent adverse events was slightly higher with moxifloxacin (67.3%) versus comparators (59.8%). Rates of drug-related adverse events (20.9% versus 20.0%) and deaths (4.3% versus 3.4%) were similar in moxifloxacin and comparator groups; none of the deaths were drug-related.

CONCLUSIONS

The data suggests that once-daily IV (or IV/PO) moxifloxacin has a comparable efficacy and safety profile to antibiotic regimens approved previously in the subgroup of patients with secondary peritonitis of mild-to-moderate severity.

Effects of β-lactam antibiotics and fluoroquinolones on human gut microbiota in relation to Clostridium difficile associated diarrhea

Clostridium difficile infections are an emerging health problem in the modern hospital environment. Severe alterations of the gut microbiome with loss of resistance to colonization against C. difficile are thought to be the major trigger, but there is no clear concept of how C. difficile infection evolves and which microbiological factors are involved. We sequenced 16S rRNA amplicons generated from DNA and RNA/cDNA of fecal samples from three groups of individuals by FLX technology: (i) healthy controls (no antibiotic therapy); (ii) individuals receiving antibiotic therapy (Ampicillin/Sulbactam, cephalosporins, and fluoroquinolones with subsequent development of C. difficile infection or (iii) individuals receiving antibiotic therapy without C. difficile infection. We compared the effects of the three different antibiotic classes on the intestinal microbiome and the effects of alterations of the gut microbiome on C. difficile infection at the DNA (total microbiota) and rRNA (potentially active) levels. A comparison of antibiotic classes showed significant differences at DNA level, but not at RNA level. Among individuals that developed or did not develop a C. difficile infection under antibiotics we found no significant differences. We identified single species that were up- or down regulated in individuals receiving antibiotics who developed the infection compared to non-infected individuals. We found no significant differences in the global composition of the transcriptionally active gut microbiome associated with C. difficile infections. We suggest that up- and down regulation of specific bacterial species may be involved in colonization resistance against C. difficile providing a potential therapeutic approach through specific manipulation of the intestinal microbiome.

Targeting the bacteria-host interface: strategies in anti-adhesion therapy

Bacterial infections are a major cause of morbidity and mortality worldwide and are increasingly problematic to treat due to the rise in antibiotic-resistant strains. It becomes more and more challenging to develop new antimicrobials that are able to withstand the ever-increasing repertoire of bacterial resistance mechanisms. This necessitates the development of alternative approaches to prevent and treat bacterial infections. One of the first steps during bacterial infection is adhesion of the pathogen to host cells. A pathogen’s ability to colonize and invade host tissues strictly depends on this process. Thus, interference with adhesion (anti-adhesion therapy) is an efficient way to prevent or treat bacterial infections. As a basis to present different strategies to interfere with pathogen adhesion, this review briefly introduces general concepts of bacterial attachment to host cells. We further discuss advantages and disadvantages of anti-adhesion treatments and issues that are in need of improvement so as to make anti-adhesion compounds a more broadly applicable alternative to conventional antimicrobials.

Changing epidemiology of Clostridium difficile-associated disease during stem cell transplantation

The incidence and severity of Clostridium difficile-associated disease (CDAD) within the general population has risen dramatically over the past decade, yet little data are available from hematopoietic stem cell transplantation (HSCT) centers. In the present study, we performed a chart review of 822 consecutive autologous and allogeneic HCST recipients treated at Northwestern Memorial Hospital between 2004 and 2008 to determine the incidence of CDAD at our institution. Variables including age, sex, diagnosis, chemotherapy regimen, transplantation type, microbial colonization, coinfections, diet, antibiotic use, neutropenic fever, comorbid conditions, time to engraftment, growth factor administration, and occurrence of graft-versus-host disease were assessed as potential risk factors for the development of CDAD. Eighty-five CDAD cases (10.3%) were identified. Bivariate analysis revealed a significant association between CDAD and neutropenic fever, administration of a neutropenic diet, ciprofloxacin and aztreonam use and duration of therapy, vancomycin and aztreonam use and duration of therapy, receipt of an allogeneic transplantation, bacterial coinfection, and vancomycin-resistant Entereococcus faecium (VRE) colonization. Cox regression analysis identified the following as factors associated with the development of CDAD: age >60 years, allogeneic transplantation, and prior VRE colonization. Allogeneic recipients with CDAD experienced increased higher rates of grades II to IV gastrointestinal graft-versus-host disease and nonrelapse mortality. A risk stratification model was developed to identify HSCT recipients at different levels of risk. With an incidence >10%, CDAD is a significant infectious complication of stem cell transplantation.

Recent changes in Clostridium difficile infection

Clostridium difficile is the main cause of nosocomial diarrhea. Diarrhea associated with C. difficile has increased incidence, morbidity, and mortality in the last few years. The major related risk factors include use of antibiotics, elderly patients and prolonged hospital stay. Many patients receive combinations of antibiotics or multiple antibiotics, which represents the main risk to develop diarrhea associated to C. difficile or its recurrence. Therefore, interventions to improve antibiotic prescribing, as well as compliance with infection control measures can reduce hospital-acquired C. difficile infections. This review addresses the epidemiological changes in C. difficile disease and its treatment.

Modeling the role of peroxisome proliferator-activated receptor γ and microRNA-146 in mucosal immune responses to Clostridium difficile

Clostridium difficile is an anaerobic bacterium that has re-emerged as a facultative pathogen and can cause nosocomial diarrhea, colitis or even death. Peroxisome proliferator-activated receptor (PPAR) γ has been implicated in the prevention of inflammation in autoimmune and infectious diseases; however, its role in the immunoregulatory mechanisms modulating host responses to C. difficile and its toxins remains largely unknown. To characterize the role of PPARγ in C. difficile-associated disease (CDAD), immunity and gut pathology, we used a mouse model of C. difficile infection in wild-type and T cell-specific PPARγ null mice. The loss of PPARγ in T cells increased disease activity and colonic inflammatory lesions following C. difficile infection. Colonic expression of IL-17 was upregulated and IL-10 downregulated in colons of T cell-specific PPARγ null mice. Also, both the loss of PPARγ in T cells and C. difficile infection favored Th17 responses in spleen and colonic lamina propria of mice with CDAD. MicroRNA (miRNA)-sequencing analysis and RT-PCR validation indicated that miR-146b was significantly overexpressed and nuclear receptor co-activator 4 (NCOA4) suppressed in colons of C. difficile-infected mice. We next developed a computational model that predicts the upregulation of miR-146b, downregulation of the PPARγ co-activator NCOA4, and PPARγ, leading to upregulation of IL-17. Oral treatment of C. difficile-infected mice with the PPARγ agonist pioglitazone ameliorated colitis and suppressed pro-inflammatory gene expression. In conclusion, our data indicates that miRNA-146b and PPARγ activation may be implicated in the regulation of Th17 responses and colitis in C. difficile-infected mice.

Epidemiology and healthcare costs of incident Clostridium difficile infections identified in the outpatient healthcare setting

OBJECTIVE

To describe the epidemiology and healthcare costs of Clostridium difficile infection (CDI) identified in the outpatient setting.

DESIGN

Population-based, retrospective cohort study.

PATIENTS

Kaiser Permanente Colorado and Kaiser Permanente Northwest members between June 1, 2005, and September 30, 2008.

METHODS

We identified persons with incident CDI and classified CDI by whether it was identified in the outpatient or inpatient healthcare setting. We collected information about baseline variables and follow-up healthcare utilization, costs, and outcomes among patients with CDI. We compared characteristics of patients with CDI identified in the outpatient versus inpatient setting.

RESULTS

We identified 3,067 incident CDIs; 56% were identified in the outpatient setting. Few strong, independent predictors of diagnostic setting were identified, although a previous stay in a nonacute healthcare institution (odds ratio [OR], 1.45 [95% confidence interval (CI), 1.13-1.86]) was statistically associated with outpatient-identified CDI, as was age from 50 to 59 years (OR, 1.64 [95% CI, 1.18-2.29]), 60 to 69 years (OR, 1.37 [95% CI, 1.03-1.82]), and 70 to 79 years (OR, 1.36 [95% CI, 1.06-1.74]), when compared with persons aged 80-89 years.

CONCLUSIONS

We found that more than one-half of incident CDIs in this population were identified in the outpatient setting. Patients with outpatient-identified CDI were younger with fewer comorbidities, although they frequently had previous exposure to healthcare. These data suggest that practitioners should be aware of CDI and obtain appropriate diagnostic testing on outpatients with CDI symptoms.

Detection, treatment, and prevention of Clostridium difficile infection

Clostridium difficile is a gram-positive anaerobic bacillus responsible for approximately 1 of 5 cases of antibiotic-associated diarrhea. C difficile infection (CDI) is defined by at least 3 unformed stools in a 24-hour period and stool, endoscopic, or histopathologic test results that indicate the presence of this bacteria. The history of CDI research can be divided into early (before 2000) and modern eras (after 2000). C difficile was first described in 1935, and the characteristics and causes of CDI as well as therapies were identified during the early era of research. During the modern era, CDI has become a more common, aggressive nosocomial infection. Our understanding of the epidemiology, diagnosis, treatment, and prevention of CDI has increased at a rapid pace. We review features of CDI diagnosis, treatment, and prevention.

Clostridium difficile: epidemiology, pathogenesis, management, and prevention of a recalcitrant healthcare-associated pathogen

Clostridium difficile is the leading cause of healthcare-associated infectious diarrhea. Although C difficile is part of normal flora in some healthy individuals, patients with selective risk factors are often vulnerable to the toxigenic potential of this virulent healthcare pathogen. The spectrum of C difficile infection (CDI) is highly variable, ranging from mild to severe illness, presenting with single to multiple disease recurrences. Current approaches to treatment are based on severity of illness, number of recurrences, and clinical presentation. Oral vancomycin and metronidazole have formed the foundation for treatment of CDI, but therapeutic failures are commonly reported, especially involving hypervirulent clones. Alternative therapies, including newer antimicrobials, probiotics, immunotherapy, and fecal transplantation, have all met with varying degrees of efficacy. Although toxigenic culture (TC) testing from anaerobic culture remains the gold standard, newer technologies, including enzyme immunoassay, common antigen (glutamate dehydrogenase) testing, and real-time polymerase chain reaction (PCR) are less time-consuming and rapid. However, TC and PCR have reported high specificity and sensitivity when compared with other laboratory tests. Because of the significant morbidity and mortality associated with CDI, a high index of suspicion is warranted. Prevention and eradication of CDI require a multidisciplinary approach, including early disease recognition through appropriate surveillance, implementation of effective contact isolation strategies, adherence to environmental controls, judicious hand hygiene, evidence-based treatment, and management that includes antibiotic stewardship, continuous education of healthcare workers, and administrative support.

Clostridia in premature neonates' gut: incidence, antibiotic susceptibility, and perinatal determinants influencing colonization

BACKGROUND

Although premature neonates (PN) gut microbiota has been studied, data about gut clostridial colonization in PN are scarce. Few studies have reported clostridia colonization in PN whereas Bacteroides and bifidobacteria have been seldom isolated. Such aberrant gut microbiota has been suggested to be a risk factor for the development of intestinal infections. Besides, PN are often treated by broad spectrum antibiotics, but little is known about how antibiotics can influence clostridial colonization based on their susceptibility patterns. The aim of this study was to report the distribution of Clostridium species isolated in feces from PN and to determine their antimicrobial susceptibility patterns. Additionally, clostridial colonization perinatal determinants were analyzed.

RESULTS

Of the 76 PN followed until hospital discharge in three French neonatal intensive care units (NICUs), 79% were colonized by clostridia. Clostridium sp. colonization, with a high diversity of species, increased throughout the hospitalization. Antibiotic courses had no effect on the clostridial colonization incidence although strains were found susceptible (except C. difficile) to anti-anaerobe molecules tested. However, levels of colonization were decreased by either antenatal or neonatal (during more than 10 days) antibiotic courses (p = 0.006 and p = 0.001, respectively). Besides, incidence of colonization was depending on the NICU (p = 0.048).

CONCLUSION

This study shows that clostridia are part of the PN gut microbiota. It provides for the first time information on the status of clostridia antimicrobial susceptibility in PN showing that strains were susceptible to most antibiotic molecules. Thus, the high prevalence of this genus is not linked to a high degree of resistance to antimicrobial agents or to the use of antibiotics in NICUs. The main perinatal determinant influencing PN clostridia colonization appears to be the NICU environment.

Clostridium difficile infection in older adults: a review and update on its management

BACKGROUND

Clostridium difficile is a main cause of health care-associated infections. The incidence and severity have been increasing. Elderly persons are at an increased risk of morbidity and mortality from C. difficile infection (CDI). Relatively few advances have been made in the treatment of CDI since it was first identified as a cause of antibiotic-associated diarrhea more than 30 years ago.

OBJECTIVE

This article reviews CDI and provides an update on its treatment, including recently published clinical practice guidelines and the recently approved drug, fidaxomicin.

METHODS

English-language literature was identified through a search of PubMed (1966-October 2011), Iowa Drug Information Service (1966-October 2011), and International Pharmaceutical Abstracts (1970-October 2011). Key search terms included Clostridium difficile, Clostridium infections, pseudomembranous colitis, antibiotic-associated diarrhea, Clostridium difficile-associated diarrhea, elderly, geriatric, epidemiology, microbiology, diagnosis, risk factors, treatment, drug therapy, vancomycin, metronidazole, and fidaxomicin.

RESULTS

Metronidazole and vancomycin remain the mainstays of CDI treatment. Current guidelines recommend oral metronidazole for initial mild to moderate episodes or first recurrence. Oral vancomycin is recommended for initial severe episodes, or first or second recurrence. Fidaxomicin was approved in 2011 for treatment of CDI, but its place in therapy has yet to be determined. Other antibiotics have been used with variable success. Saccharomyces boulardii is the only probiotic that has shown efficacy in CDI. Fecal transplants have been used successfully in some patients, but randomized studies are needed. Immune therapy with a vaccine and monoclonal antibodies is being studied in clinical trials.

CONCLUSIONS

Treatment of CDI is challenging due to the limited number of drugs that have proven to be effective, concerns about antibiotic resistance, and recurring disease. The recent approval of fidaxomicin provides a new alternative. Immune therapy will likely play a greater role in the future.

Cefoperazone-treated mice as an experimental platform to assess differential virulence of Clostridium difficile strains

The toxin-producing bacterium C. difficile is the leading cause of antibiotic-associated colitis, with an estimated 500,000 cases C. difficile infection (CDI) each year in the US with a cost approaching 3 billion dollars. Despite the significance of CDI, the pathogenesis of this infection is still being defined. The recent development of tractable murine models of CDI will help define the determinants of C. difficile pathogenesis in vivo. To determine if cefoperazone-treated mice could be utilized to reveal differential pathogenicity of C. difficile strains, 5-8 week old C57BL/6 mice were pretreated with a 10 d course of cefoperazone administered in the drinking water. Following a 2-d recovery period without antibiotics, the animals were orally challenged with C. difficile strains chosen to represent the potential range of virulence of this organism from rapidly fatal to nonpathogenic. Animals were monitored for loss of weight and clinical signs of colitis. At the time of harvest, C. difficile strains were isolated from cecal contents and the severity of colitis was determined by histopathologic examination of the cecum and colon. Cefoperazone treated mice challenged with C. difficile strains VPI 10463 and BI1 exhibited signs of severe colitis while infection with 630 and F200 was subclinical. This increased clinical severity was correlated with more severe histopathology with significantly more edema, inflammation and epithelial damage encountered in the colons of animals infected with VPI 10463 and BI1. Disease severity also correlated with levels of C. difficile cytotoxic activity in intestinal tissues and elevated blood neutrophil counts. Cefoperazone treated mice represent a useful model of C. difficile infection that will help us better understand the pathogenesis and virulence of this re-emerging pathogen.

Incidence of and risk factors for community-associated Clostridium difficile infection: a nested case-control study

BACKGROUND

Clostridium difficile is the most common cause of nosocomial infectious diarrhea in the United States. However, recent reports have documented that C. difficile infections (CDIs) are occurring among patients without traditional risk factors. The purpose of this study was to examine the epidemiology of CA-CDI, by estimating the incidence of CA-CDI and HA-CDI, identifying patient-related risk factors for CA-CDI, and describing adverse health outcomes of CA-CDI.

METHODS

We conducted a population-based, retrospective, nested, case-control study within the University of Iowa Wellmark Data Repository from January 2004 to December 2007. We identified persons with CDI, determined whether infection was community-associated (CA) or hospital-acquired (HA), and calculated incidence rates. We collected demographic, clinical, and pharmacologic information for CA-CDI cases and controls (i.e., persons without CDI). We used conditional logistic regression to estimate the odds ratios (ORs) for potential risk factors for CA-CDI.

RESULTS

The incidence rates for CA-CDI and HA-CDI were 11.16 and 12.1 cases per 100,000 person-years, respectively. CA-CDI cases were more likely than controls to receive antimicrobials (adjusted OR, 6.09 [95% CI 4.59-8.08]) and gastric acid suppressants (adjusted OR, 2.30 [95% CI 1.56-3.39]) in the 180 days before diagnosis. Controlling for other covariates, increased risk for CA-CDI was associated with use of beta-lactam/beta-lactamase inhibitors, cephalosporins, clindamycin, fluoroquinolones, macrolides, and penicillins. However, 27% of CA-CDI cases did not receive antimicrobials in the 180 days before their diagnoses, and 17% did not have any traditional risk factors for CDI.

CONCLUSIONS

Our study documented that the epidemiology of CDI is changing, with CA-CDI occurring in populations not traditionally considered "high-risk" for the disease. Clinicians should consider this diagnosis and obtain appropriate diagnostic testing for outpatients with persistent or severe diarrhea who have even remote antimicrobial exposure.

Incidence of and risk factors for community-associated Clostridium difficile infection: a nested case-control study

Background

Clostridium difficile is the most common cause of nosocomial infectious diarrhea in the United States. However, recent reports have documented that C. difficile infections (CDIs) are occurring among patients without traditional risk factors. The purpose of this study was to examine the epidemiology of CA-CDI, by estimating the incidence of CA-CDI and HA-CDI, identifying patient-related risk factors for CA-CDI, and describing adverse health outcomes of CA-CDI.

Methods

We conducted a population-based, retrospective, nested, case-control study within the University of Iowa Wellmark Data Repository from January 2004 to December 2007. We identified persons with CDI, determined whether infection was community-associated (CA) or hospital-acquired (HA), and calculated incidence rates. We collected demographic, clinical, and pharmacologic information for CA-CDI cases and controls (i.e., persons without CDI). We used conditional logistic regression to estimate the odds ratios (ORs) for potential risk factors for CA-CDI.

Results

The incidence rates for CA-CDI and HA-CDI were 11.16 and 12.1 cases per 100,000 person-years, respectively. CA-CDI cases were more likely than controls to receive antimicrobials (adjusted OR, 6.09 [95% CI 4.59-8.08]) and gastric acid suppressants (adjusted OR, 2.30 [95% CI 1.56-3.39]) in the 180 days before diagnosis. Controlling for other covariates, increased risk for CA-CDI was associated with use of beta-lactam/beta-lactamase inhibitors, cephalosporins, clindamycin, fluoroquinolones, macrolides, and penicillins. However, 27% of CA-CDI cases did not receive antimicrobials in the 180 days before their diagnoses, and 17% did not have any traditional risk factors for CDI.

Conclusions

Our study documented that the epidemiology of CDI is changing, with CA-CDI occurring in populations not traditionally considered "high-risk" for the disease. Clinicians should consider this diagnosis and obtain appropriate diagnostic testing for outpatients with persistent or severe diarrhea who have even remote antimicrobial exposure.

The interplay between microbiome dynamics and pathogen dynamics in a murine model of Clostridium difficile Infection

Clostridium difficile infection (CDI) arises in the setting of antibiotic administration where disruption of the normal indigenous gut microbiota leads to susceptibility to C. difficile colonization and colitis. Using a murine model of CDI, we demonstrate that changes in the community structure of the indigenous gut microbiota are associated with the loss of colonization resistance against C. difficile. Several antibiotic regimens were tested in combination for the ability to overcome colonization resistance, including a five antibiotic cocktail consisting of kanamycin, gentamicin, colistin, metronidazole, and vancomycin administered in drinking water for three days, a single intraperitoneal dose of clindamycin or 10 days of cefoperazone in drinking water. Following antibiotic treatment animals were challenged with 105 colony forming units of C. difficile strain VPI 10463 via oral gavage. Animals that received the antibiotic cocktail and clindamycin prior to C. difficile challenge followed one of two clinical courses, either becoming clinically ill and moribund within 2-4 days post challenge, or remaining clinically well. Animals that became clinically ill developed histologically severe colitis. These histopathologic findings were significantly less severe in animals that remained clinically well. Analysis of 16S rRNA gene sequences retrieved from gut tissue at necropsy demonstrated that Proteobacteria dominated the gut microbiota in clinically ill animals. In contrast, the gut microbial community of clinically well animals more closely resembled untreated animals, which were dominated by members of the Firmicutes. All animals that received cefoperazone treatment prior to C. difficile challenge were clinically ill and moribund by 2-5 days post challenge in a dose dependent manner. The gut communities in these animals were dominated by C.difficile suggesting that cefoperazone treatment resulted in a greater loss in colonization resistance. Thus, the severity of colitis that arises in this system reflects the interplay between the expansion of C. difficile in the gut community and the ecologic dynamics of the indigenous microbial community as it recovers from antibiotic perturbation. We demonstrate that altering the balance of these two opposing processes alters clinical outcome and thus may lead to novel preventative and therapeutic approaches for CDI.

Clostridium difficile isolates resistant to fluoroquinolones in Italy: emergence of PCR ribotype 018

Recent evidence strongly suggests an association between the use of fluoroquinolones and Clostridium difficile infection (CDI). Resistance to fluoroquinolones has been described not only in the hypervirulent strain 027, but also in other important PCR ribotypes circulating in hospital settings. In a European prospective study conducted in 2005, strains resistant to moxifloxacin represented 37.5% of C. difficile clinical isolates. In this study, we investigated a sample of 147 toxigenic C. difficile isolates, collected in Italy from 1985 to 2008, for the presence of mutations in gyr genes that conferred resistance to fluoroquinolones based on a LightCycler assay. Results were confirmed by the determination of MICs for moxifloxacin. Strains resistant to moxifloxacin were also investigated for resistance to three other fluoroquinolones and for a possible association between fluoroquinolone and macrolide-lincosamide-streptogramin B resistance. C. difficile isolates were typed by PCR ribotyping. In total, 50 clinical isolates showed substitutions in gyr genes and were resistant to fluoroquinolones. Ninety-six percent of the C. difficile resistant isolates showed the substitution Thr82-to-Ile in GyrA, as already observed in the majority of resistant strains worldwide. A significant increase of resistance (P < 0.001) was observed in the period 2002 to 2008 (56% resistant) compared to the period 1985 to 2001 (10% resistant). Coresistance with erythromycin and/or clindamycin was found in 96% (48/50) of the isolates analyzed and, interestingly, 84% of resistant strains were erm(B) negative. The majority of the fluoroquinolone-resistant isolates belonged to PCR ribotype 126 or 018. PCR ribotype 126 was the most frequently found from 2002 to 2005, whereas PCR ribotype 018 was predominant in 2007 and 2008 and still represents the majority of strains typed in our laboratory. Overall, the results demonstrate an increasing number of C. difficile strains resistant to fluoroquinolones in Italy and changes in the prevalence and type of C. difficile isolates resistant to fluoroquinolones circulating over time.

Safety considerations of fluoroquinolones in the elderly: an update

The fluoroquinolones ciprofloxacin, levofloxacin, moxifloxacin and gemifloxacin are widely used for the treatment of various types of bacterial infections. Overall, these antibacterial agents can be considered safe and well tolerated drugs. Comparative studies have evaluated the use of quinolones in elderly and younger populations. Although age per se does not seem to decrease their tolerability, specific adverse effects of the quinolones must be considered when they are chosen for antibacterial treatment. Renal function declines consistently with age and doses of renally excreted quinolones (e.g. ofloxacin, levofloxacin, gatifloxacin) need to be adjusted if a clinically relevant reduction of creatinine clearance is identified. Reactions of the gastrointestinal tract, such as nausea, dyspepsia, vomiting or diarrhoea, are among the most often registered adverse drug reactions during therapy with fluoroquinolones. Treatment with a quinolone causes diarrhoea less frequently than treatment with other classes of antimicrobials. Conflicting data have been published with respect to the incidence of Clostridium difficile-associated diarrhoea in quinolone-treated patients. Hypersensitivity reactions, often manifested on the skin, occur less commonly during therapy with quinolones than, for example, during therapy with beta-lactam antibacterials. Adverse reactions of the CNS are of particular concern in the elderly population. Given the CNS excitatory effects of quinolones, elderly patients should be monitored carefully for such symptoms. It is likely that many signs of possible adverse reactions, such as confusion, weakness, loss of appetite, tremor or depression, are often mistakenly attributed to old age and remain unreported. Quinolones should be used with caution in patients with known or suspected CNS disorders that predispose to seizures (e.g. severe cerebral arteriosclerosis or epilepsy). Quinolones can cause QT interval prolongation. They should be avoided in patients with known prolongation of the QT interval, patients with uncorrected hypokalaemia or hypomagnesaemia and patients receiving class IA (e.g. quinidine, procainamide) or class III (e.g. amiodarone, sotalol) antiarrhythmic agents. Tendinitis and tendon ruptures are recognized as quinolone-induced adverse effects that can occur during treatment or as late as several months after treatment. Chronic renal diseases, concomitant use of corticosteroids and age >60 years are known risk factors for quinolone-induced tendopathies. Overall, the specific adverse-effect profile of quinolones must be considered when they are chosen for treatment of bacterial infections. Because of physiological changes in renal function and when certain co-morbidities are present, some special considerations are necessary when elderly patients are treated with these drugs.

The prophylactic effects of platelet-leucocyte gel in osteomyelitis: an experimental study in a rabbit model

Platelet-leucocyte gel (PLG), a new biotechnological blood product, has hitherto been used primarily to treat chronic ulcers and to promote soft-tissue and bone regeneration in a wide range of medical fields. In this study, the antimicrobial efficacy of PLG against Staphylococcus aureus (ATCC 25923) was investigated in a rabbit model of osteomyelitis. Autologous PLG was injected into the tibial canal after inoculation with Staph. aureus. The prophylactic efficacy of PLG was evaluated by microbiological, radiological and histological examination. Animal groups included a treatment group that received systemic cefazolin and a control group that received no treatment. Treatment with PLG or cefazolin significantly reduced radiological and histological severity scores compared to the control group. This result was confirmed by a significant reduction in the infection rate and the number of viable bacteria. Although not comparable to cefazolin, PLG exhibited antimicrobial efficacy in vivo and therefore represents a novel strategy to prevent bone infection in humans.

Recent Publications on Medications and Pharmacy

Hospital Pharmacy presents this feature to keep pharmacists abreast of new publications in the medical/pharmacy literature. Articles of interest regarding a broad scope of topics are abstracted monthly.