Antibiotic resistance in Enterobacteriaceae: what impact on the efficacy of antibiotic prophylaxis in colorectal surgery?

Oral Antibiotics Alone versus Oral Antibiotics Combined with Mechanical Bowel Preparation for Elective Colorectal Surgery: A Propensity Score-Matching Re-Analysis of the iCral 2 and 3 Prospective Cohorts

The evidence regarding the role of oral antibiotics alone (oA) or combined with mechanical bowel preparation (MoABP) for elective colorectal surgery remains controversial. A prospective database of 8359 colorectal resections gathered over a 32-month period from 78 Italian surgical units (the iCral 2 and 3 studies), reporting patient-, disease-, and procedure-related variables together with 60-day adverse events, was re-analyzed to identify a subgroup of 1013 cases (12.1%) that received either oA or MoABP. This dataset was analyzed using a 1:1 propensity score-matching model including 20 covariates. Two well-balanced groups of 243 patients each were obtained: group A (oA) and group B (MoABP). The primary endpoints were anastomotic leakage (AL) and surgical site infection (SSI) rates. Group A vs. group B showed a significantly higher AL risk [14 (5.8%) vs. 6 (2.5%) events; OR: 3.77; 95%CI: 1.22-11.67; p = 0.021], while no significant difference was recorded between the two groups regarding SSIs. These results strongly support the use of MoABP for elective colorectal resections.

Colonization of multidrug-resistant Gram-negative bacteria increases risk of surgical site infection after hemorrhoidectomy: a cross-sectional study of two centers in southern China

PURPOSE

The present study aims to determine the rectoanal colonization rate and risk factors for the colonization of present multidrug-resistant bacteria (MDRBs). In addition, the relationship between MDRB colonization and surgical site infection (SSI) following hemorrhoidectomy was explored.

METHODS

A cross-sectional study was conducted in the Department of Colorectal Surgery of two hospitals. Patients with hemorrhoid disease, who underwent hemorrhoidectomy, were included. The pre-surgical screening of multidrug-resistant Gram-negative bacteria (MDR-GNB) colonization was performed using rectal swabs on the day of admission. Then, the MDRB colonization rate was determined through the rectal swab. Logistic regression models were established to determine the risk factors for MDRB colonization and SSI after hemorrhoidectomy. A p-value of < 0.05 was considered statistically significant.

RESULTS

A total of 432 patients met the inclusion criteria, and the MDRB colonization prevalence was 21.06% (91/432). The independent risk factors for MDRB colonization were as follows: patients who received ≥ 2 categories of antibiotic treatment within 3 months (odds ratio (OR): 3.714, 95% confidence interval (CI): 1.436-9.605, p = 0.007), patients with inflammatory bowel disease (IBD; OR: 6.746, 95% CI: 2.361-19.608, p < 0.001), and patients with high serum uric acid (OR: 1.006, 95% CI: 1.001-1.010, p = 0.017). Furthermore, 41.57% (37/89) of MDRB carriers and 1.81% (6/332) of non-carriers developed SSIs, with a total incidence of 10.21% (43/421). Based on the multivariable model, the rectoanal colonization of MDRBs (OR: 32.087, 95% CI: 12.052-85.424, p < 0.001) and hemoglobin < 100 g/L (OR: 4.130, 95% CI: 1.556-10.960, p = 0.004) were independently associated with SSI after hemorrhoidectomy.

CONCLUSION

The rectoanal colonization rate of MDRBs in hemorrhoid patients is high, and this was identified as an independent risk factor for SSI after hemorrhoidectomy.

A rapid evidence assessment exploring whether antimicrobial resistance complicates non-infectious health conditions and healthcare services, 2010-20

Antimicrobial resistance (AMR) is one of the greatest public health threats at this time. While there is a good understanding of the impacts of AMR on infectious diseases, an area of less focus is the effects AMR may be having on non-communicable health conditions (such as cancer) and healthcare services (such as surgery). Therefore, this study aimed to explore what impact AMR is currently having on non-communicable health conditions, or areas of health services, where AMR could be a complicating factor impacting on the ability to treat the condition and/or health outcomes. To do this, a rapid evidence assessment of the literature was conducted, involving a systematic approach to searching and reviewing the evidence. In total, 101 studies were reviewed covering surgery, organ transplants, cancer, ICUs, diabetes, paediatric patients, immunodeficiency conditions, liver and kidney disease, and physical trauma. The results showed limited research in this area and studies often use a selective population, making the results difficult to generalize. However, the evidence showed that for all health conditions and healthcare service areas reviewed, at least one study demonstrated a higher risk of death for patients with resistant infections, compared with no or drug-susceptible infections. Poor health outcomes were also associated with resistant infections in some instances, such as severe sepsis and failure of treatments, as well as a greater need for invasive medical support. While there are gaps in the evidence base requiring further research, efforts are also needed within policy and practice to better understand and overcome these challenges.

Cost-Effectiveness Analysis of the Prophylactic Use of Ertapenem for the Prevention of Surgical Site Infections after Elective Colorectal Surgery

Standard surgical antimicrobial prophylaxis (SAP) regimens are less effective in preventing surgical site infections (SSIs) due to rising antimicrobial resistance (AMR) rates, particularly for patients undergoing colorectal surgery. This study aimed to evaluate whether ertapenem should be a preferred strategy for the prevention of SSIs following elective colorectal surgery compared to three standard SAP regimens: amoxicillin-clavulanate, cefoxitin, and cefazolin plus metronidazole. A cost-effectiveness analysis was conducted using decision tree models. Probabilities of SSIs and AMR-SSIs, costs, and effects (in terms of quality-adjusted life-years) were considered in the assessment of the alternative strategies. Input parameters integrated real data from the Italian surveillance system for SSIs with data from the published literature. A sensitivity analysis was conducted to assess the potential impact of the decreasing efficacy of standard SAP regimens in preventing SSIs. According to our models, ertapenem was the most cost-effective strategy only when compared to amoxicillin-clavulanate, but it did not prove to be superior to cefoxitin and cefazolin plus metronidazole. The sensitivity analysis found ertapenem would be the most cost-effective strategy compared to these agents if their failure rate was more than doubled. The findings of this study suggest ertapenem should not be a preferred strategy for SAP in elective colorectal surgery.

The Relative Role of Bile Bacterial Isolation on Outcome in Stent-Bearing Patients Undergoing Pancreatoduodenectomy

BACKGROUND

Biliary stenting leads to antimicrobial-resistant (AMR) microorganism retrievement in bile cultures. However, the impact of intraoperative bile colonizations on post-pancreaticoduodenectomy complications remains unclear. Aims of our study were to characterize the bile flora of stented patients in comparison with postoperative cultures and to analyze whether patterns of drug resistance affected postoperative outcomes.

METHODS

We analyzed records from stent-bearing pancreaticoduodenectomy patients at 3 European centers. Intra- and postoperative cultures were compared and classified as multidrug sensitive (MDS), multidrug resistant (MDR), and extensively drug resistant (XDR). Thirty-day complications were graded according to international standards.

RESULTS

Out of 270 patients, intraoperative cultures were positive in 219 (81.1%) cases. In 36.7%, MDS species were isolated; in 35.9%, MDR; and in 8.5%, XDR species. A solid correspondence between the species isolated intra- and postoperatively (p < 0.001) was observed. Intraoperative MDR/XDR isolation was associated with an increased rate of surgical (p = 0.043) and infectious complications (p = 0.030), but not severe complication rate (p = 0.973). Postoperative MDR/XDR isolation was associated with higher risk of major complications (45.6% vs. 15.8%, p < 0.001), postoperative pancreatic fistula (p < 0.001), and post-pancreatectomy hemorrhage (p = 0.002). By multivariate analysis, intraoperative AMR isolation was associated with high likelihood of postoperative AMR infections. However, only in 43/121 cases, intraoperative MDR/XDR microorganisms turned into the occurrence of postoperative infections.

CONCLUSION

Intraoperative AMR isolates do not translate into severe outcomes, despite being significantly associated with surgical and infectious complications.

Comparative genetics of Enterococcus faecalis intestinal tissue isolates before and after surgery in a rat model of colon anastomosis

We have recently demonstrated that collagenolytic Enterococcus faecalis plays a key and causative role in the pathogenesis of anastomotic leak, an uncommon but potentially lethal complication characterized by disruption of the intestinal wound following segmental removal of the colon (resection) and its reconnection (anastomosis). Here we hypothesized that comparative genetic analysis of E. faecalis isolates present at the anastomotic wound site before and after surgery would shed insight into the mechanisms by which collagenolytic strains are selected for and predominate at sites of anastomotic disruption. Whole genome optical mapping of four pairs of isolates from rat colonic tissue obtained following surgical resection (herein named “pre-op” isolates) and then 6 days later from the anastomotic site (herein named “post-op” isolates) demonstrated that the isolates with higher collagenolytic activity formed a distinct cluster. In order to perform analysis at a deeper level, a single pair of E. faecalis isolates (16A pre-op and 16A post-op) was selected for whole genome sequencing and assembled using a hybrid assembly algorithm. Comparative genomics demonstrated absence of multiple gene clusters, notably a pathogenicity island in the post-op isolate. No differences were found in the fsr-gelE-sprE genes (EF1817-1822) responsible for regulation and production of collagenolytic activity. Analysis of unique genes among the 16A pre-op and post-op isolates revealed the predominance of transporter systems-related genes in the pre-op isolate and phage-related and hydrolytic enzyme-encoding genes in the post-op isolate. Despite genetic differences observed between pre-op and post-op isolates, the precise genetic determinants responsible for their differential expression of collagenolytic activity remains unknown.

Oral Polyphosphate Suppresses Bacterial Collagenase Production and Prevents Anastomotic Leak Due to Serratia marcescens and Pseudomonas aeruginosa

OBJECTIVE

The objective of this study was to determine the effect of polyphosphate on intestinal bacterial collagenase production and anastomotic leak in mice undergoing colon surgery.

BACKGROUND

We have previously shown that anastomotic leak can be caused by intestinal pathogens that produce collagenase. Because bacteria harbor sensory systems to detect the extracellular concentration of phosphate which controls their virulence, we tested whether local phosphate administration in the form of polyphosphate could attenuate pathogen virulence and prevent leak without affecting bacterial growth.

METHODS

Groups of mice underwent a colorectal anastomosis which was then exposed to collagenolytic strains of either Serratia marcescens or Pseudomonas aeruginosa via enema. Mice were then randomly assigned to drink water or water supplemented with a 6-mer of polyphosphate (PPi-6). All mice were sacrificed on postoperative day 10 and anastomoses assessed for leakage, the presence of collagenolytic bacteria, and anastomotic PPi-6 concentration.

RESULTS

PPi-6 markedly attenuated collagenase and biofilm production, and also swimming and swarming motility in both S. marcescens and P. aeruginosa while supporting their normal growth. Mice drinking PPi-6 demonstrated increased levels of PPi-6 and decreased colonization of S. marcescens and P. aeruginosa, and collagenase activity at anastomotic tissues. PPi-6 prevented anastomotic abscess formation and leak in mice after anastomotic exposure to S. marcescens and P. aeruginosa.

CONCLUSIONS

Polyphosphate administration may be an alternative approach to prevent anastomotic leak induced by collagenolytic bacteria with the advantage of preserving the intestinal microbiome and its colonization resistance.

Association between rectal colonization with Highly Resistant Gram-negative Rods (HR-GNRs) and subsequent infection with HR-GNRs in clinical patients: A one year historical cohort study

Objective

Rectal colonization with Highly Resistant Gram-negative Rods (HR-GNRs) probably precedes infection. We aimed to assess the association between rectal HR-GNR colonization and subsequent HR-GNR infection in clinical patients during a follow-up period of one year in a historical cohort study design.

Methods

Rectal HR-GNR colonization was assessed by culturing. Subsequent development of infection was determined by assessing all clinical microbiological culture results extracted from the laboratory information system including clinical data regarding HR-GNR infections. A multivariable logistic regression model was constructed with HR-GNR rectal colonization as independent variable and HR-GNR infection as dependent variable. Gender, age, antibiotic use, historic clinical admission and previous (HR-GNR) infections were included as possible confounders.

Results

1133 patients were included of whom 68 patients (6.1%) were colonized with a HR-GNR. In total 22 patients with HR-GNR infections were detected. Urinary tract infections were most common (n = 14, 63.6%), followed by bloodstream infections (n = 5, 22.7%) and other infections (n = 8, 36.4%). Eight out of 68 HR-GNR colonized patients (11.8%) developed a subsequent HR-GNR infection compared to 14 out of 1065 HR-GNR negative patients (1.3%), resulting in an odds ratio (95% CI) of 7.1 (2.8–18.1) in the multivariable logistic regression analyses.

Conclusions

Rectal colonization with a HR-GNR was a significant risk factor for a subsequent HR-GNR infection.

This implies that historical colonization culture results should be considered in the choice of empirical antibiotic therapy to include coverage of the cultured HR-GNR, at least in critically ill patients.

Is the efficacy of antibiotic prophylaxis for surgical procedures decreasing? Systematic review and meta-analysis of randomized control trials

OBJECTIVE

Rising antibiotic resistance could reduce the effectiveness of antibiotics in preventing postoperative infections. We investigated trends in the efficacy of antibiotic prophylaxis regimens for 3 commonly performed surgical procedures-appendectomy, cesarean section, and colorectal surgery-and 1 invasive diagnostic procedure, transrectal prostate biopsy (TRPB).

DESIGN

Systematic review and meta-analysis.

METHODS

We searched PubMed and Cochrane databases (through October 31, 2017) for randomized control trials (RCTs) that measured the efficacy of antibiotic prophylaxis for 4 index procedures in preventing postoperative infections (surgical site infections [SSIs] following the 3 surgical procedures and a combination of urinary tract infections [UTIs] and sepsis following TRPB).

RESULTS

Of 399 RCTs, 74 studies (9 appendectomy, 11 cesarean section, 39 colorectal surgery, and 15 TRPB) were included. Multilevel logistic regression models with random intercepts for each study showed no statistically significant increase in SSIs over time for appendectomy (adjusted odds ratio [aOR] per year, 1.03; 95% confidence interval [CI], 0.92-1.16; P=.57), cesarean section (aOR per year, 1.01; 95% CI, 0.96-1.05; P=.80), and TRPB (aOR per year, 0.95; 95% CI, 0.77-1.18; P=.67). However, there was a significant increase in SSIs proportion following colorectal surgery (aOR per year, 1.049; 95% CI, 1.03-1.07; P&lt;.001).

CONCLUSION

The efficacy of antibiotic prophylaxis agents in preventing SSIs following colorectal surgery has declined. Small number of RCTs and low infections rates limited our ability to assess true effect for simple appendectomy, cesarean section, or TRPB.

[Spectrum of pathogens in postoperative complications of visceral surgery : The problem of multidrug resistance]

In general surgery the etiology of surgical site infections has not significantly changed over the last 30 years. Gram-positive bacteria, e.g. coagulase negative staphylococci (CNS), Staphylococcus aureus and Enterococcus spp. as well as Gram-negative bacteria, e.g. Escherichia coli, Enterobacter spp., Klebsiella spp. and Pseudomonas aeruginosa, are the most common findings. Although in general surgery 10% of the S. aureus causing postoperative wound infections were methicillin resistant (MRSA), no cases of multidrug-resistant Gram-negative (MRGN) bacteria were reported. Yeasts (particularly Candida spp.) are rarely the pathogen causing surgical site infections (≤3%) and concomitant risk factors are typical (e.g. diabetes, chemotherapy, immunosuppression and malnutrition). Viruses are rarely the cause of surgical site infections. Transmission can occur by HBV, HCV or HIV positive surgical staff or in organ transplantations and postoperative reactivation of persistent infections is possible (especially for HBV, HCV, CMV, EBV and HIV). The principles for prevention of surgical site infections are dealt with as consequences of preoperative colonization by MRSA, methicillin-sensitive S. aureus (MSSA) and MRGN and reviewed with respect to screening, perioperative antibiotic prophylaxis and decolonization. In nosocomial peritonitis, the selection of antibiotics should consider previous antibiotic treatment. A single intra-abdominal detection of Candida spp. usually does not require antimycotic treatment in postoperatively stable and immunocompetent patients but is recommended in severe community-acquired or nosocomial peritonitis. Viral infections can be avoided by screening of organ donors and serological surveillance of surgery personnel.

Consequences of Increases in Antibiotic Resistance Pattern on Outcome of Pancreatic Resection for Cancer

BACKGROUND

The role of drug-resistance infections on surgical outcomes is controversial. The aim of the study was to determine whether increase antibiotic resistance was an independent risk factor for development of major non-infectious postoperative complications.

METHODS

This work included a multicenter cohort study of patients who underwent pancreatic resections for cancer over a 3-year interval. The primary outcome was major non-infectious complication rate developing after the occurrence of multi-drug sensitive (MDS) infection, multi-drug-resistant infection (MDR), and extensive drug-resistant (XDR) infection. Multivariate logistic regression models were used to adjust for patient and operative effects.

RESULTS

Eligible patients (517) were selected for the analysis. One hundred and thirteen (21.8%) patients had major non-infectious complications with a rate of 12.9% in the no infection group, 29.3% in the MSD, 41.5% in the MDR, and 58.8% in the XDR (p < 0.001). The median time of infection occurrence was postoperative days 4 (2-7 IQR) and 7 (3-12 IQR) non-infectious complications. At multivariate analysis, the risk of having major non-infectious complications was 2.67 (95% CI 1.24-5.77, P = 0.012) for MDR, 5.04 (95% CI 2.35-10.80, P < 0.001) for MDR, and 9.64 (95% CI 2.71-34.28, P < 0.001) for XDR.

CONCLUSION

Antimicrobial resistance is significantly associated with the risk of major non-infectious morbidity.

[Multidrug resistant gram-negative bacteria : Clinical management pathway for patients undergoing elective interventions in visceral surgery]

BACKGROUND

Only a few antibiotics are available for treatment of infections with multidrug resistant gram-negative bacteria (MRGN). The management of patients with MRGN colonization or infection is therefore of great importance with respect to postoperative morbidity and mortality.

OBJECTIVE

This article presents a description of the management pathway for patients with MRGN colonization.

RESULTS

The prevalence of MRGN colonization is increasing, particularly for persons with contact to the healthcare system in endemic regions. The Robert Koch Institute demands an obligatory MRGN screening and isolation of patients with geographic or contact-related exposure risk for colonization with 4MRGN (carbapenemase producers). For patients with elective visceral interventions a prompt sensitive screening before inpatient admission is wise. Strict basic hygiene measures are essential to prevent transmission. Isolation is indicated for patients with 4MRGN and also for patients with 3MRGN in risk areas. Risk patients with unknown status are preemptively isolated. Perioperative antibiotic prophylaxis should be administered as a single dose and in cases of MRGN colonization substances effective against MRGN should be given if necessary. For treatment of secondary/tertiary peritonitis with a risk of MRGN involvement and in hemodynamically instable patients, effective extended spectrum beta-lactamase (ESBL) substances should primarily be used (e.g. tigecycline, carbapenems, ceftolozane/tazobactam and ceftazidim/avibactam). Ceftazidim/avibactam is also a novel therapy option for infections with carbapenamase-producing enterobacteria.

CONCLUSION

The structured implementation of MRGN screening in patients at risk, stringent basic hygiene, targeted isolation and adequate calculated antibiotic therapy are essential measures in the management of the problem of MRGN in visceral surgery.

Potential burden of antibiotic resistance on surgery and cancer chemotherapy antibiotic prophylaxis in the USA: a literature review and modelling study

BACKGROUND

The declining efficacy of existing antibiotics potentially jeopardises outcomes in patients undergoing medical procedures. We investigated the potential consequences of increases in antibiotic resistance on the ten most common surgical procedures and immunosuppressing cancer chemotherapies that rely on antibiotic prophylaxis in the USA.

METHODS

We searched the published scientific literature and identified meta-analyses and reviews of randomised controlled trials or quasi-randomised controlled trials (allocation done on the basis of a pseudo-random sequence-eg, odd/even hospital number or date of birth, alternation) to estimate the efficacy of antibiotic prophylaxis in preventing infections and infection-related deaths after surgical procedures and immunosuppressing cancer chemotherapy. We varied the identified effect sizes under different scenarios of reduction in the efficacy of antibiotic prophylaxis (10%, 30%, 70%, and 100% reductions) and estimated the additional number of infections and infection-related deaths per year in the USA for each scenario. We estimated the percentage of pathogens causing infections after these procedures that are resistant to standard prophylactic antibiotics in the USA.

FINDINGS

We estimate that between 38·7% and 50·9% of pathogens causing surgical site infections and 26·8% of pathogens causing infections after chemotherapy are resistant to standard prophylactic antibiotics in the USA. A 30% reduction in the efficacy of antibiotic prophylaxis for these procedures would result in 120,000 additional surgical site infections and infections after chemotherapy per year in the USA (ranging from 40,000 for a 10% reduction in efficacy to 280,000 for a 70% reduction in efficacy), and 6300 infection-related deaths (range: 2100 for a 10% reduction in efficacy, to 15,000 for a 70% reduction). We estimated that every year, 13,120 infections (42%) after prostate biopsy are attributable to resistance to fluoroquinolones in the USA.

INTERPRETATION

Increasing antibiotic resistance potentially threatens the safety and efficacy of surgical procedures and immunosuppressing chemotherapy. More data are needed to establish how antibiotic prophylaxis recommendations should be modified in the context of increasing rates of resistance.

FUNDING

DRIVE-AB Consortium.

Reflections on HIS 2014: In praise of enthusiasts

Medical conferences have had a bad press recently. They have been accused of leaving nothing but indifferent research and an enormous carbon footprint. They are also likely to contribute to 'intervention bias' in healthcare, in that the speakers tend to be selected from among the more enthusiastic interventionists and charismatic optimists. But this weakness is arguably also an important strength, for they can be the vehicle by which participants are inspired to innovate and evaluate. It is difficult to predict the outcome of interventions aimed at prevention and control of infection because they involve interactions between people and complex systems, not to mention the invisible agents of infection. Progress therefore depends largely on the empirical approach - trial and error. In this context we need both enthusiasts to inspire trial and sceptics to expose error. Conferences deserve support for encouraging debate between enthusiasts and sceptics, for providing a forum for cross-fertilization between sub-specialties, and for inspiring trainees as well as practitioners. The papers presented in this issue of JHI illustrate the wide range of contemporary challenges in healthcare-associated infection, and summarize the 'state of the art' of infection prevention and control.