Colonization and resistance dynamics of gram-negative bacteria in patients during and after hospitalization

Management of pneumonia in the critically ill

Pneumonias continue to be major public health issues and are commonly encountered in the intensive care setting. The most common types of pneumonia leading to critical illness include severe community acquired pneumonia, hospital acquired pneumonia, and ventilator associated pneumonia. Early evaluation, diagnosis, and escalation to appropriate levels of care are imperative to improving survival. Treatment remains challenging with the need to balance antibiotic stewardship and minimizing patient harm. As evidenced in the most recent society guidelines, the identification of risk factors for severe disease and the causative pathogens are crucial in guiding the most appropriate therapy.

Prevalence and Patterns of Antimicrobial Resistance among Escherichia coli and Staphylococcus spp. in a Veterinary University Hospital

The occurrence of antimicrobial resistance in commensal strains of Escherichia coli and Staphylococcus spp. was investigated in 320 samples collected from patients and the environment of a veterinary university hospital-specifically, the consultation area (CA) and intensive care unit (ICU). E. coli was isolated in 70/160 samples (44%), while Staphylococcus spp. were isolated in 110/160 (69%) samples. The occurrence of multidrug-resistant (MDR) isolates from CA and ICU admission were similar for E. coli (1/12 (8%) versus 4/27 (15%), respectively) and Staphylococcus spp. (10/19 (53%) versus 26/50 (52%), respectively). MDR E. coli isolates increased significantly at hospital discharge (18/31; 58%; p = 0.008). Antimicrobial treatment administered during hospitalization was a risk factor for carriage of MDR E. coli (OR, 23.9; 95% CI: 1.18-484.19; p = 0.04) and MDR Staphylococcus spp. (OR, 19.5; 95% CI 1.30-292.76; p = 0.02), respectively. The odds ratio for MDR E. coli was 41.4 (95% CI 2.13-806.03; p = 0.01), if the administration of fluoroquinolones was evaluated. The mecA gene was detected in 19/24 (79%) coagulase-positive Staphylococcus spp. isolates resistant to oxacillin. High rates of MDR Staphylococcus spp. were reported. Hospitalization in the ICU and antimicrobial treatment were risk factors for colonization by MDR commensal bacteria.

High Acquisition Rate of Gram-Negative Multi-Drug Resistant Organism Colonization During Hospitalization: A Perspective from a High Endemic Setting

Objective

The aim of the study was to compare the rate of gram-negative multi-drug resistant organism (GN-MDRO) colonization at admission and during hospitalization and to describe the strains and antibiotic resistance genes acquired during hospitalization.

Methods

Rectal swabs were collected from patients hospitalized at the National Trauma Center (NTC), Mongolia, at the time of admission and after 14 days of hospitalization as has been detailed on our previous study. GN-MDRO antibiotic resistance was determined using EUCAST standards, and resistance genes were detected using multiplex PCR.

Results

A total of 158 patients were screened, and baseline colonization rate at admission was 29.1% (46/158). The rate went up to 69.9% (110/158) after 14 days of hospitalization (p<0.001). Of all participants, 74 patients (46.8%) screened GN-MDRO negative at admission acquired colonization by day 14. Other 36 patients (22.8%) maintained colonization that was screened positive at both time points. Only 38 patients (24.0%) remained free of GN-MDRO during hospitalization. There was a difference in GN-MDRO acquisition between these groups. Patients who were negative at admission acquired up to 3 GN-MDRO species, and there were 10 different species isolated. Reversely, patients who were screened positive at both time points had fairly homogenous isolates; up to 5 species of Enterobacterales were identified at admission and day 14 hospitalization. Overall, Enterobacterales were the dominant colonizers (61.4%, 97/158), and all Enterobacterales were resistant to cefotaxime as CTX-M resistance was our inclusion criteria.

Conclusion

GN-MDRO baseline colonization rate on admission was high and, alarmingly, doubled during hospitalization in the study area. Enterobacterales was the predominant colonizer and was highly resistant to 3rd generation cephalosporin. This data supports a need for an improved infection control policy including routine surveillance of the GN-MDROs and improved antibiotic stewardship program.

Pathogenesis of Gram-Negative Bacteremia

Gram-negative bacteremia is a devastating public health threat, with high mortality in vulnerable populations and significant costs to the global economy. Concerningly, rates of both Gram-negative bacteremia and antimicrobial resistance in the causative species are increasing. Gram-negative bacteremia develops in three phases. First, bacteria invade or colonize initial sites of infection. Second, bacteria overcome host barriers, such as immune responses, and disseminate from initial body sites to the bloodstream. Third, bacteria adapt to survive in the blood and blood-filtering organs. To develop new therapies, it is critical to define species-specific and multispecies fitness factors required for bacteremia in model systems that are relevant to human infection. A small subset of species is responsible for the majority of Gram-negative bacteremia cases, including Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Acinetobacter baumannii The few bacteremia fitness factors identified in these prominent Gram-negative species demonstrate shared and unique pathogenic mechanisms at each phase of bacteremia progression. Capsule production, adhesins, and metabolic flexibility are common mediators, whereas only some species utilize toxins. This review provides an overview of Gram-negative bacteremia, compares animal models for bacteremia, and discusses prevalent Gram-negative bacteremia species.

Homology analysis between clinically isolated extraintestinal and enteral Klebsiella pneumoniae among neonates

Background

Klebsiella pneumoniae is a leading cause of hospital-associated (HA) infections. It has been reported that gastrointestinal colonization (GI) is likely to be a common and significant reservoir for the transmission and infections of K. pneumoniae in both adults and neonates. However, the homologous relationship between clinically isolated extraintestinal and enteral K. pneumoniae in neonates hasn’t been characterized yet.

Results

Forty-three isolates from 21 neonatal patients were collected in this study. The proportion of carbapenem resistance was 62.8%. There were 12 patients (12/21, 57.4%) whose antibiotic resistance phenotypes, genotypes, and ST types (STs) were concordant. Six sequence types were detected using MLST, with ST37 and ST54 being the dominant types. The results of MLST were consist with the results of PFGE.

Conclusions

These data showed that there might be a close homologous relationship between extraintestinal K. pneumoniae (EXKP) and enteral K. pneumoniae (EKP) in neonates, indicating that the K. pneumoniae from the GI tract is possibly to be a significant reservoir for causing extraintestinal infections.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12866-020-02073-2.

Impact of microbiome-based interventions on gastrointestinal pathogen colonization in the intensive care unit

In the intensive care unit (ICU), colonization of the gastrointestinal tract by potentially pathogenic bacteria is common and often precedes clinical infection. Though effective in the short term, traditional antibiotic-based decolonization methods may contribute to rising resistance in the long term. Novel therapies instead focus on restoring gut microbiome equilibrium to achieve pathogen colonization resistance. This review summarizes the existing data regarding microbiome-based approaches to gastrointestinal pathogen colonization in ICU patients with a focus on prebiotics, probiotics, and synbiotics.

The effect of short-course antibiotics on the resistance profile of colonizing gut bacteria in the ICU: a prospective cohort study

BACKGROUND

The need for early antibiotics in the intensive care unit (ICU) is often balanced against the goal of antibiotic stewardship. Long-course antibiotics increase the burden of antimicrobial resistance within colonizing gut bacteria, but the dynamics of this process are not fully understood. We sought to determine how short-course antibiotics affect the antimicrobial resistance phenotype and genotype of colonizing gut bacteria in the ICU by performing a prospective cohort study with assessments of resistance at ICU admission and exactly 72 h later.

METHODS

Deep rectal swabs were performed on 48 adults at the time of ICU admission and exactly 72 h later, including patients who did and did not receive antibiotics. To determine resistance phenotype, rectal swabs were cultured for methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus (VRE). In addition, Gram-negative bacterial isolates were cultured against relevant antibiotics. To determine resistance genotype, quantitative PCR (qPCR) was performed from rectal swabs for 87 established resistance genes. Within-individual changes in antimicrobial resistance were calculated based on culture and qPCR results and correlated with exposure to relevant antibiotics (e.g., did β-lactam antibiotic exposure associate with a detectable change in β-lactam resistance over this 72-h period?).

RESULTS

Of 48 ICU patients, 41 (85%) received antibiotics. Overall, there was no increase in the antimicrobial resistance profile of colonizing gut bacteria during the 72-h study period. There was also no increase in antimicrobial resistance after stratification by receipt of antibiotics (i.e., no detectable increase in β-lactam, vancomycin, or macrolide resistance regardless of whether patients received those same antibiotics). This was true for both culture and PCR. Antimicrobial resistance pattern at ICU admission strongly predicted resistance pattern after 72 h.

CONCLUSIONS

Short-course ICU antibiotics made little detectable difference in the antimicrobial resistance pattern of colonizing gut bacteria over 72 h in the ICU. This provides an improved understanding of the dynamics of antimicrobial resistance in the ICU and some reassurance that short-course antibiotics may not adversely impact the stewardship goal of reducing antimicrobial resistance.

Hypervirulent Klebsiella pneumoniae

Hypervirulent K. pneumoniae (hvKp) is an evolving pathotype that is more virulent than classical K. pneumoniae (cKp). hvKp usually infects individuals from the community, who are often healthy. Infections are more common in the Asian Pacific Rim but are occurring globally. hvKp infection frequently presents at multiple sites or subsequently metastatically spreads, often requiring source control. hvKp has an increased ability to cause central nervous system infection and endophthalmitis, which require rapid recognition and site-specific treatment. The genetic factors that confer hvKp's hypervirulent phenotype are present on a large virulence plasmid and perhaps integrative conjugal elements. Increased capsule production and aerobactin production are established hvKp-specific virulence factors. Similar to cKp, hvKp strains are becoming increasingly resistant to antimicrobials via acquisition of mobile elements carrying resistance determinants, and new hvKp strains emerge when extensively drug-resistant cKp strains acquire hvKp-specific virulence determinants, resulting in nosocomial infection. Presently, clinical laboratories are unable to differentiate cKp from hvKp, but recently, several biomarkers and quantitative siderophore production have been shown to accurately predict hvKp strains, which could lead to the development of a diagnostic test for use by clinical laboratories for optimal patient care and for use in epidemiologic surveillance and research studies.

Usefulness of telemedicine for home ventilator-dependent children

INTRODUCTION

Medical care for ventilator-dependent children must avoid hospital confinement, which is detrimental to the patient, their family and Paediatric Intensive Care Unit. Our objective was to assess the role of telemedicine in facilitating early and permanent discharge of such patients to home care.

METHODS

This was a prospective clinical study (2007-2017) in tracheotomised ventilator-dependent children. We used a Big Data Telemedicine home system (Medlinecare 2.1) from the Paediatric Intensive Care Unit. Specialised home-nursing services were available. Clinical events were analysed using the Chi-square test (significance p < 0.05). Families subsequently completed a satisfaction survey. The Paediatric Intensive Care Unit management indicators were analysed.

RESULTS

All of our ventilator-dependent children were included (n=12). At time of discharge from the Paediatric Intensive Care Unit, they all required continuous mechanical ventilation and met the criteria of groups I-III of the OTA classification. In the first two years there were 141 events; the main cause was respiratory (69.5%, p < 0.001) and telemedicine was the main care approach (86.5%, p < 0.001). Eleven events required hospitalisation (7.8%) but 38 (27.0%) hospitalisations were avoided. The emergency readmission time accounted for 0.99% of the total time. Six patients were decannulated, and one patient died due to primary cardiac arrest. All the families considered that the telemedicine had helped to avoid hospital visits, was not an intrusion into their privacy, and improved the child's safety and quality of life. An improvement in Paediatric Intensive Care Unit indicators was achieved.

DISCUSSION

Telemedicine facilitated early and permanent discharge of our ventilator-dependent children to home care without affecting their quality of care.

Oropharyngeal colonization: epidemiology, treatment and ventilator-associated pneumonia prevention

Oropharyngeal (OP) colonization and ventilator-associated pneumonia (VAP) mechanisms are tightly linked. A significant within-population variation in OP colonization has been described, with its composition being dependent from patients' severity. For instance, healthy subjects have a very low rate in Gram-negative bacteria (GNB) colonization, while its rate rises in comorbid patients, reaching high proportions in ICU patients. Various factors can be put forward to explain the modifications of hospital acquired OP. ICU patients might suffer from underlying diseases; the gastric reflux induced by the presence of nasogastric tubes and the patients' position influences OP colonization; salivary composition might influence OP content, as it modulates bacterial adhesion and induces reversible bacterial changes enhancing bacterial binding. The transition from OP colonization to VAP has been shown in numerous studies, with the digestive tract acting as a filter, or as a reservoir. Some therapies have been investigated to modulate OP colonization, in order to reduce the risk for VAP. Among those, mammalian antimicrobial peptides have been shown effective in reducing GNB colonization in healthy subjects, but failed in preventing VAP in ICU patients. The widely used chlorhexidine was tested in numerous trials. Data on its efficacy are conflicting, and meta-analyses yield discordant results. Above all, several drawbacks have aroused: a poor tolerance of concentrated solutions; an increased risk of death in the less severe patients; and a reduced susceptibility towards chlorhexidine of number of VAP pathogens. Proanthocyanidins, used to prevent Escherichia coli adhesion to the urothelium, have been tested in mice model of pneumonia with interesting results. Some complementary data are needed before moving to clinical research. Future research paths should include a reappraisal of OP colonization; finding better formulations for chlorhexidine; define the best populations to target oral decontamination and developing other strategies to prevent and treat OP colonization.

Transmission of resistant Gram-negative bacteria to healthcare personnel gowns and gloves during care of residents in community-based nursing facilities

OBJECTIVE

To estimate the risk of transmission of antibiotic-resistant Gram-negative bacteria (RGNB) to gowns and gloves worn by healthcare personnel (HCP) when providing care to residents of community-based nursing facilities to identify the types of care and resident characteristics associated with transmission.

DESIGN

Prospective observational study.Settings and participantsResidents and HCP from 13 community-based nursing facilities in Maryland and Michigan.

METHODS

Perianal swabs were collected from residents and cultured to detect RGNB. HCP wore gowns and gloves during usual care activities, and at the end of each interaction, these were swabbed in a standardized manner. Transmission of RGNB from a colonized resident to gowns and gloves was estimated. Odds ratios (ORs) of transmission associated with type of care or resident characteristic were calculated.

RESULTS

We enrolled 403 residents and their HCP in this study. Overall, 19% of enrolled residents with a perianal swab (n=399) were colonized with at least 1 RGNB. RGNB transmission to either gloves or gowns occurred during 11% of the 584 interactions. Showering the resident, hygiene or toilet assistance, and wound dressing changes were associated with a high risk of transmission. Glucose monitoring and assistance with feeding or medication were associated with a low risk of transmission. Residents with a pressure ulcer were 3 times more likely to transmit RGNB than residents without one (OR, 3.3; 95% confidence interval [CI], 1.0-11.1).

CONCLUSIONS

Gown and glove use in community nursing facilities should be prioritized for certain residents and care interactions that are deemed a high risk for transmission.

Rapid gastrointestinal loss of Clostridial Clusters IV and XIVa in the ICU associates with an expansion of gut pathogens

Commensal gastrointestinal bacteria resist the expansion of pathogens and are lost during critical illness, facilitating pathogen colonization and infection. We performed a prospective, ICU-based study to determine risk factors for loss of gut colonization resistance during the initial period of critical illness. Rectal swabs were taken from adult ICU patients within 4 hours of admission and 72 hours later, and analyzed using 16S rRNA gene sequencing and selective culture for vancomycin-resistant Enterococcus (VRE). Microbiome data was visualized using principal coordinate analyses (PCoA) and assessed using a linear discriminant analysis algorithm and logistic regression modeling. 93 ICU patients were analyzed. At 72 hours following ICU admission, there was a significant decrease in the proportion of Clostridial Clusters IV/XIVa, taxa that produce short chain fatty acids (SCFAs). At the same time, there was a significant expansion in Enterococcus. Decreases in Cluster IV/XIVa Clostridia were associated with loss of gut microbiome colonization resistance (reduced diversity and community stability over time). In multivariable analysis, both decreased Cluster IV/XIVa Clostridia and increased Enterococcus after 72 hours were associated with receipt of antibiotics. Cluster IV/XIVa Clostridia, although a small fraction of the overall gastrointestinal microbiome, drove distinct clustering on PCoA. During initial treatment for critical illness, there was a loss of Cluster IV/XIVa Clostridia within the distal gut microbiome which associated with an expansion of VRE and with a loss of gut microbiome colonization resistance. Receipt of broad-spectrum antibiotics was associated with these changes.

Clinical impact of delayed catheter removal for patients with central-venous-catheter-related Gram-negative bacteraemia

BACKGROUND

Gram-negative bacteria are increasingly the cause of catheter-related bloodstream infection (CRBSI), and the prevalence of multi-drug-resistant strains is rising rapidly. This study evaluated the impact of delayed central venous catheter (CVC) removal on clinical outcomes in patients with Gram-negative CRBSI.

METHODS

Between January 2007 and December 2016, patients with Gram-negative bacteraemia and CVC placement, from two tertiary care hospitals, were included retrospectively. Cases with CVC removal more than three days after onset of bacteraemia or without CVC removal were classified as having delayed CVC removal.

RESULTS

In total, 112 patients were included. Of these, 78 had CRBSI (43 definite and 35 probable) and 34 had Gram-negative bacteraemia from another source (non-CRBSI). Enterobacteriaceae were less common pathogens in patients with CRBSI than in patients with non-CRBSI (11.5% vs 41.3%; P<0.001). Delayed CVC removal was associated with increased 30-day mortality (40.5% vs 11.8%; P=0.01) in patients with Gram-negative CRBSI; this was not seen in patients with non-CRBSI (25.0% vs 14.3%; P>0.99). Delayed CVC removal [odds ratio (OR) 6.8], multi-drug-resistant (MDR) Gram-negative bacteraemia (OR 6.3) and chronic renal failure (OR 11.1) were associated with 30-day mortality in patients with CRBSI. The protective effect of early CVC removal on mortality was evident in the MDR group (48.3% vs 18.2%; P=0.03), but not in the non-MDR group (11.1% vs 0%; P=0.43).

CONCLUSION

CVCs should be removed early to improve clinical outcomes in patients with Gram-negative CRBSI, especially in settings where MDR isolates are prevalent.

Transmission of Resistant Gram-Negative Bacteria to Health Care Worker Gowns and Gloves during Care of Nursing Home Residents in Veterans Affairs Community Living Centers

The objectives of the study were to estimate the risk of transmission of antibiotic-resistant Gram-negative bacteria (RGNB) to gowns and gloves (G&G) worn by health care workers (HCWs) when providing care to nursing home residents and to identify the types of care and resident characteristics associated with transmission. A multicenter, prospective observational study was conducted with residents and HCWs from Veterans Affairs (VA) nursing homes. Perianal swabs to detect RGNB were collected from residents. HCWs wore G&G during usual care activities, and the G&G were swabbed at the end of the interaction in a standardized manner. Transmission of RGNB from a colonized resident to G&G by type of care was measured. Odds ratios (ORs) associated with type of care or resident characteristics were estimated. Fifty-seven (31%) of 185 enrolled residents were colonized with ≥1 RGNB. RGNB transmission to HCW gloves or gowns occurred during 9% of the interactions (n = 905): 7% to only gloves and 2% to only gowns. Bathing the resident and providing hygiene and toilet assistance were associated with a high risk of transmission. Glucose monitoring and assistance with feeding or medication were associated with a low risk of transmission. In addition, antibiotic use by the resident was strongly associated with greater transmission (OR, 2.51; P < 0.01). RGNB were transferred to HCWs during ∼9% of visits. High-risk types of care were identified for which use of G&G may be prioritized. Antibiotic use was associated with 2.5 times greater risk of transmission, emphasizing the importance of antibiotic stewardship. (This study has been registered at ClinicalTrials.gov under registration no. NCT01350479.).

Increased resistance of gram-negative urinary pathogens after kidney transplantation

BACKGROUND

Urinary tract infection is the most common complication after kidney transplantation. It can cause severe sepsis and transplant loss. Emergence of drug resistance among gram-negative urinary pathogens is the current challenge for urinary tract infection treatment after kidney transplantation.

METHODS

This study analyzes the antimicrobial susceptibility of gram-negative urinary pathogens after kidney transplantation from 2009 to 2012 at the Transplant Outpatient Clinic of the University Hospital Essen, Germany. Kidney transplant patients at the University Hospital Essen receive regular follow up examinations after transplantation. Midstream urines were examined for bacteriuria at each follow up visit.

RESULTS

From 2009 to 2012 15.741 urine samples were obtained from 859 patients. In 2985 (19%) samples bacterial growth was detected. The most frequently detected gram-negative bacteria were E.coli 1109 (37%), Klebsiella spp. 242 (8%) and Pseudomonas aeruginosa 136 (4.5%). Klebsiella spp. showed a significant increase of resistance to trimethoprim-sulfamethoxazole by 19% (p = 0.02), ciprofloxacin by 15% (p = 0.01) and ceftazidime by 17% (p = 0.004). E.coli and P. aeruginosa isolates presented no significant differences of antimicrobial susceptibility to the analyzed antibiotics.

CONCLUSIONS

Antimicrobial resistance of Klebsiella spp. increased significant to trimethoprim-sulfamethoxazole, ciprofloxacin and ceftazidime from 2009 to 2012.

Empiric antibiotic selection and risk prediction of drug-resistant pathogens in community-onset pneumonia

PURPOSE OF REVEIW

Empiric antibiotic selection in community-onset pneumonia is complicated by uncertainty regarding risk of drug-resistant pathogens (DRPs). The healthcare-associated pneumonia (HCAP) criteria have limited predictive value and lead to unnecessary antibiotic use. Better methods of predicting risk of DRP and selecting empiric antibiotics are needed. Here we give an update on risk factors for DRP, available risk prediction models, and treatment strategy in patients with pneumonia.

RECENT FINDINGS

Evidence supporting factors that contribute to risk of DRP has improved since the advent of HCAP. Many of these risk factors have been reproducibly identified in heterogeneous populations. Newer methods of predicting DRP based on these factors demonstrate better performance than HCAP. Recent innovations include the potential to discriminate between risk for methicillin-resistant Staphylococcus aureus and other DRP, and use of severity as a modifier of treatment threshold. However, there is wide variation in included predictor variables, and at proposed thresholds most scores still favor overtreatment.

SUMMARY

Until reliable molecular diagnostics are available, additional development and validation of decision support models integrating local resistance rates, estimated DRP risk, severity, and threshold for anti-DRP antibiotics are needed. Once optimized models are identified, implementation studies will be needed to confirm safety and efficacy.

Molecular Epidemiology of Colonizing and Infecting Isolates of Klebsiella pneumoniae

K. pneumoniae commonly infects hospitalized patients, and these infections are increasingly resistant to carbapenems, the antibiotics of last resort for life-threatening bacterial infections. To prevent and treat these infections, we must better understand how K. pneumoniae causes disease and discover new ways to predict and detect infections. This study demonstrates that colonization with K. pneumoniae in the intestinal tract is strongly linked to subsequent infection. This finding helps to identify a potential time frame and possible approach for intervention: the colonizing strain from a patient could be isolated as part of a risk assessment, and antibiotic susceptibility testing could guide empirical therapy if the patient becomes acutely ill.

Klebsiella pneumoniae is among the most common causes of hospital-acquired infections and has emerged as an urgent threat to public health due to carbapenem antimicrobial resistance. K. pneumoniae commonly colonizes hospitalized patients and causes extraintestinal infections such as urinary tract infection, bloodstream infection (septicemia), and pneumonia. If colonization is an intermediate step before infection, then detection and characterization of colonizing isolates could enable strategies to prevent or empirically treat K. pneumoniae infections in hospitalized patients. However, the strength of the association between colonization and infection is unclear. To test the hypothesis that hospitalized patients become infected with their colonizing strain, 1,765 patients were screened for rectal colonization with K. pneumoniae, and extraintestinal isolates from these same patients were collected over a 3-month period in a cohort study design. The overall colonization prevalence was 23.0%. After adjustment for other patient factors, colonization was significantly associated with subsequent infection: 21 of 406 (5.2%) colonized patients later had extraintestinal infection, compared to 18 of 1,359 (1.3%) noncolonized patients (adjusted odds ratio [OR], 4.01; 95% confidence interval, 2.08 to 7.73; P < 0.001). Despite a high diversity of colonizing isolates, 7/7 respiratory, 4/4 urinary, and 2/5 bloodstream isolates from colonized patients matched the patient corresponding rectal swab isolates, based on wzi capsular typing, multilocus sequence typing (MLST), and whole-genome sequence analysis. These results suggest that K. pneumoniae colonization is directly associated with progression to extraintestinal infection.

IMPORTANCE K. pneumoniae commonly infects hospitalized patients, and these infections are increasingly resistant to carbapenems, the antibiotics of last resort for life-threatening bacterial infections. To prevent and treat these infections, we must better understand how K. pneumoniae causes disease and discover new ways to predict and detect infections. This study demonstrates that colonization with K. pneumoniae in the intestinal tract is strongly linked to subsequent infection. This finding helps to identify a potential time frame and possible approach for intervention: the colonizing strain from a patient could be isolated as part of a risk assessment, and antibiotic susceptibility testing could guide empirical therapy if the patient becomes acutely ill.

Derivation and Multicenter Validation of the Drug Resistance in Pneumonia Clinical Prediction Score

The health care-associated pneumonia (HCAP) criteria have a limited ability to predict pneumonia caused by drug-resistant bacteria and favor the overutilization of broad-spectrum antibiotics. We aimed to derive and validate a clinical prediction score with an improved ability to predict the risk of pneumonia due to drug-resistant pathogens compared to that of HCAP criteria. A derivation cohort of 200 microbiologically confirmed pneumonia cases in 2011 and 2012 was identified retrospectively. Risk factors for pneumonia due to drug-resistant pathogens were evaluated by logistic regression, and a novel prediction score (the drug resistance in pneumonia [DRIP] score) was derived. The score was then validated in a prospective, observational cohort of 200 microbiologically confirmed cases of pneumonia at four U.S. centers in 2013 and 2014. The DRIP score (area under the receiver operator curve [AUROC], 0.88 [95% confidence interval {CI}, 0.82 to 0.93]) performed significantly better (P = 0.02) than the HCAP criteria (AUROC, 0.72 [95% CI, 0.64 to 0.79]). At a threshold of ≥4 points, the DRIP score demonstrated a sensitivity of 0.82 (95% CI, 0.67 to 0.88), a specificity of 0.81 (95% CI, 0.73 to 0.87), a positive predictive value (PPV) of 0.68 (95% CI, 0.56 to 0.78), and a negative predictive value (NPV) of 0.90 (95% CI, 0.81 to 0.93). By comparison, the performance of HCAP criteria was less favorable: sensitivity was 0.79 (95% CI, 0.67 to 0.88), specificity was 0.65 (95% CI, 0.56 to 0.73), PPV was 0.53 (95% CI, 0.42 to 0.63), and NPV was 0.86 (95% CI, 0.77 to 0.92). The overall accuracy of the HCAP criteria was 69.5% (95% CI, 62.5 to 75.7%), whereas that of the DRIP score was 81.5% (95% CI, 74.2 to 85.6%) (P = 0.005). Unnecessary extended-spectrum antibiotics were recommended 46% less frequently by applying the DRIP score (25/200, 12.5%) than by use of HCAP criteria (47/200, 23.5%) (P = 0.004), without increasing the rate at which inadequate treatment recommendations were made. The DRIP score was more predictive of the risk of pneumonia due to drug-resistant pathogens than HCAP criteria and may have the potential to decrease antibiotic overutilization in patients with pneumonia. Validation in larger cohorts of patients with pneumonia due to all causes is necessary.

Carriage of beta-lactamase-producing Enterobacteriaceae among nursing home residents in north Lebanon

BACKGROUND

Multidrug-resistant (MDR) Enterobacteriaceae can cause severe infections with high morbidity, mortality, and health care costs. Individuals can be fecal carriers of these resistant organisms. Data on the extent of MDR Enterobacteriaceae fecal carriage in the community setting in Lebanon are very scarce. The aim of this study was to investigate the fecal carriage of MDR Enterobacteriaceae among the elderly residents of two nursing homes located in north Lebanon.

METHODS

Over a period of 4 months, five fecal swab samples were collected from each of 68 elderly persons at regular intervals of 3-4 weeks. Fecal swabs were subcultured on selective media for the screening of resistant organisms. The phenotypic detection of extended-spectrum beta-lactamase (ESBL), AmpC, metallo-beta-lactamase (MBL), and Klebsiella pneumoniae carbapenemase (KPC) production was performed using the beta-lactamase inhibitors ethylenediaminetetraacetic acid, phenylboronic acid, and cloxacillin. A temocillin disk was used for OXA-48. Multiplex PCRs were used for the genotypic detection of ESBL and carbapenemase genes, and sequencing was performed to identify CTX-M-15. The medical records of each subject were reviewed on a regular basis in order to assess the risk factors associated with MDR Enterobacteriaceae fecal carriage.

RESULTS

Over the study period, 76.5% of the recruited elderly persons were at least one-time carriers. A total of 178 isolates were obtained. Phenotypic testing revealed that 91.5% of them were ESBL producers, 4% were AmpC producers, 2.8% were co-producers of ESBL and AmpC, and 1.7% were co-producers of OXA-48 and ESBL. Recent antibiotic intake was found to be the only independent risk factor associated with the fecal carriage of MDR Enterobacteriaceae.

CONCLUSIONS

The high prevalence of MDR Enterobacteriaceae detected in this study and the emergence of carbapenem resistance is alarming. Efficient infection control measures and antibiotic stewardship programs are urgently needed in these settings in order to limit the spread of resistant strains.

Systematic review of the literature and evidence-based recommendations for antibiotic prophylaxis in trauma: results from an Italian consensus of experts

BACKGROUND

Antibiotic prophylaxis is frequently administered in severe trauma. However, the risk of selecting resistant bacteria, a major issue especially in critical care environments, has not been sufficiently investigated. The aim of the present study was to provide guidelines for antibiotic prophylaxis for four different trauma-related clinical conditions, taking into account the risks of antibiotic-resistant bacteria selection, thus innovating previous guidelines in the field.

METHODS

The MEDLINE database was searched for studies comparing antibiotic prophylaxis to controls (placebo or no antibiotic administration) in four clinical traumatic conditions that were selected on the basis of the traumatic event frequency and/or infection severity. The selected studies focused on the prevention of early ventilator associated pneumonia (VAP) in comatose patients with traumatic brain injury, of meningitis in severe basilar skull fractures, of wound infections in long-bone open fractures. Since no placebo-controlled study was available for deep surgical site-infections prevention in abdominal trauma with enteric contamination, we compared 24-hour and 5-day antibiotic prophylaxis policies. A separate specific research focused on the question of antibiotic-resistant bacteria selection caused by antibiotic prophylaxis, an issue not adequately investigated by the selected studies. Randomised trials, reviews, meta-analyses, observational studies were included. Data extraction was carried out by one author according to a predefined protocol, using an electronic form. The strength of evidence was stratified and recommendations were given according to the Grading of Recommendations Assessment, Development and Evaluation (GRADE) criteria.

RESULTS

Uncertain evidence deserving further studies was found for two-dose antibiotic prophylaxis for early VAP prevention in comatose patients. In the other cases the risk of resistant-bacteria selection caused by antibiotic administration for 48 hours or more, outweighed potential benefits.

CONCLUSIONS

When accounting for antibiotic-resistant bacteria selection we found no evidence in favour of antibiotic prophylaxis lasting two or more days in the studied clinical conditions.

Predicting risk of drug-resistant organisms in pneumonia: moving beyond the HCAP model

BACKGROUND

Clinical management of community-acquired pneumonia (CAP) is increasingly complicated by antibiotic resistance. CAP due to pathogens resistant to guideline-recommended drugs (CAP-DRP) has increased. 2005 ATS/IDSA guidelines introduced a new category, healthcare-associated pneumonia (HCAP), and recommend extended-spectrum antibiotic treatment for patients meeting HCAP criteria. However, the predictive value of the HCAP model is limited and data suggest that outcomes are not improved using HCAP guideline-concordant therapy. Better methods to predict risk of CAP-DRP are needed.

METHODS

We reviewed currently published literature on the performance status of HCAP as a predictive tool and studies describing additional risk factors for CAP-DRP. We also summarize the performance characteristics of the currently published alternative clinical prediction scores and compare them to that of the HCAP model.

RESULTS

In addition to the five risk factors incorporated in HCAP, at least 13 other factors have been identified. The independent predictive value of any single factor is low, but accumulating factors results in increased risk of CAP-DRP. The performance characteristics of 9 clinical prediction scores are reviewed. Nearly all of the scores outperformed HCAP in their study populations. However, no single model has yet demonstrated adequate specificity to minimize unnecessary antibiotic use, while retaining sufficient sensitivity to prevent inadequate initial empiric antibiotic therapy when validated across a wide range of CAP-DRP prevalence.

CONCLUSIONS

Additional development and validation of prediction scores based upon more refined risk factors for CAP-DRP is needed. Once an accurate, adequately validated prediction score is available, an interventional trial will be needed to determine clinical impact.

Extended-spectrum beta-lactamase-producing bacteria are not detected in supragingival plaque samples from human fecal carriers of ESBL-producing Enterobacteriaceae

BACKGROUND

The prevalence of infections caused by Cefotaximase-Munich (CTX-M)-type extended-spectrum beta-lactamase-producing Enterobacteriaceae (ESBL-E) has rapidly increased during the past 15 years. Enterobacteriaceae are commonly found in the gastrointestinal tract and long-term intestinal carriage is considered important for the spread of ESBL and as a source of clinical infections. Oral biofilm such as supragingival plaque is known to contain numerous antibiotic resistance determinants and may also represent a poorly investigated site for ESBL carriage and further spread.

OBJECTIVE

To investigate possible carriage of ESBL-producing bacteria in supragingival plaque of known fecal carriers of these bacteria.

DESIGN

We screened for the presence of aerobic and anaerobic ESBL-producing bacteria and bla CTX-M in supragingival plaque samples from healthy human adults with culture-verified fecal carriage of CTX-M-producing Escherichia coli. The presence or absence of Enterobacteriaceae and ESBL-producing bacteria in plaque samples was evaluated using culture-based methods and consensus CTX-M PCR.

RESULTS

Oral samples were obtained from 17 participants with known previous carriage of ESBL-producing E. coli. No ESBL-producing bacteria or ESBL genes were detected using culture-based and molecular methods. One colony of Rahnella aquatilis harboring the class A ESBL gene bla RAHN-1/2 was identified in an oral sample from one of the participants.

CONCLUSION

This pilot study supports the notion that the presence of CTX-M-producing bacteria is uncommon in oral plaque of healthy human adult fecal carriers. Due to the limited number of persons tested, a low prevalence of oral ESBL-carriage in healthy adults or carriage in selected groups of patients cannot be excluded. To our knowledge, this is the first description of an R. aquatilis with the RAHN-1/2 gene in the oral cavity.

Severe sepsis facilitates intestinal colonization by extended-spectrum-β-lactamase-producing Klebsiella pneumoniae and transfer of the SHV-18 resistance gene to Escherichia coli during antimicrobial treatment

Infections caused by multidrug-resistant pathogens are frequent and life threatening in critically ill patients. To investigate whether severe sepsis affects gut colonization by resistant pathogens and genetic exchange between opportunistic pathogens, we tested the intestinal-colonization ability of an extended-spectrum beta-lactamase-producing Klebsiella pneumoniae strain carrying the SHV-18 resistance gene and the transfer ability of the resistance gene to endogenous Escherichia coli under ceftriaxone treatment in rats with burn injury only or severe sepsis induced by burns plus endotoxin exposure. Without ceftriaxone treatment, the K. pneumoniae strain colonized the intestine in both septic and burned rats for a short time, with clearance occurring earlier in burn-only rats but never in sham burn rats. In both burned and septic rats, the colonization level of the challenge strain dropped at the beginning and then later increased during ceftriaxone treatment, after which it declined gradually. This pattern coincided with the change in resistance of K. pneumoniae to ceftriaxone during and after ceftriaxone treatment. Compared with burn-only injury, severe sepsis had a more significant effect on the change in antimicrobial resistance to ceftriaxone. Only in septic rats was the resistance gene successfully transferred from the challenge strain to endogenous E. coli during ceftriaxone treatment; the gene persisted for at least 4 weeks after ceftriaxone treatment. We concluded that severe sepsis can facilitate intestinal colonization by an exogenous resistant pathogen and the transfer of the resistance gene to a potential endogenous pathogen during antimicrobial treatment.

Improved ICU design reduces acquisition of antibiotic-resistant bacteria: a quasi-experimental observational study

Introduction

The role of ICU design and particularly single-patient rooms in decreasing bacterial transmission between ICU patients has been debated. A recent change in our ICU allowed further investigation.

Methods

Pre-move ICU-A and pre-move ICU-B were open-plan units. In March 2007, ICU-A moved to single-patient rooms (post-move ICU-A). ICU-B remained unchanged (post-move ICU-B). The same physicians cover both ICUs. Cultures of specified resistant organisms in surveillance or clinical cultures from consecutive patients staying >48 hours were compared for the different ICUs and periods to assess the effect of ICU design on acquisition of resistant organisms.

Results

Data were collected for 62, 62, 44 and 39 patients from pre-move ICU-A, post-move ICU-A, pre-move ICU-B and post-move ICU-B, respectively. Fewer post-move ICU-A patients acquired resistant organisms (3/62, 5%) compared with post-move ICU-B patients (7/39, 18%; P = 0.043, P = 0.011 using survival analysis) or pre-move ICU-A patients (14/62, 23%; P = 0.004, P = 0.012 on survival analysis). Only the admission period was significant for acquisition of resistant organisms comparing pre-move ICU-A with post-move ICU-A (hazard ratio = 5.18, 95% confidence interval = 1.03 to 16.06; P = 0.025). More antibiotic-free days were recorded in post-move ICU-A (median = 3, interquartile range = 0 to 5) versus post-move ICU-B (median = 0, interquartile range = 0 to 4; P = 0.070) or pre-move ICU-A (median = 0, interquartile range = 0 to 4; P = 0.017). Adequate hand hygiene was observed on 140/242 (58%) occasions in post-move ICU-A versus 23/66 (35%) occasions in post-move ICU-B (P < 0.001).

Conclusions

Improved ICU design, and particularly use of single-patient rooms, decreases acquisition of resistant bacteria and antibiotic use. This observation should be considered in future ICU design.

Risk factors for dogs becoming rectal carriers of multidrug-resistant Escherichia coli during hospitalization

This study aimed to identify risk factors for dogs becoming rectal carriers of multidrug-resistant (MDR) Escherichia coli while hospitalized in a veterinary teaching hospital. Exposures to potential risk factors, including treatments, hospitalization, and interventions during a 42-day pre-admission period and hospitalization variables, were assessed for 90 cases and 93 controls in a retrospective, risk-based, case-control study. On multivariable analyses, hospitalization for >6 days [odds ratio (OR) 2·91-8·00], treatment with cephalosporins prior to admission (OR 5·04, 95% CI 1·25-20·27), treatment with cephalosporins for >1 day (OR 5·18, 95% CI 1·86-14·41), and treatment with metronidazole (OR 7·17, 95% CI 1·01-50·79) while hospitalized were associated with increased risk of rectal carriage of MDR E. coli during hospitalization. The majority of rectal isolates obtained during the study period conformed to MDR E. coli clonal groups previously obtained from extraintestinal infections. These results can assist the development of improved infection control guidelines for the management of dogs in veterinary hospitals to prevent the occurrence of nosocomial clinical infections.

Risk factors for multidrug-resistant Escherichia coli rectal colonization of dogs on admission to a veterinary hospital

This study aimed to identify risk factors for intestinal colonization with multidrug-resistant (MDR) E. coli in dogs on admission to a veterinary teaching hospital. Exposures to potential risk factors, including prior treatments, hospitalizations and interventions during the 42 days prior to admission were assessed for 82 case admissions and 82 time-matched controls in a retrospective prevalence-based case-control study of 20 months duration. On multivariable analyses, risk of MDR E. coli colonization on admission was increased with prior hospitalization for 4-7 days and >7 days relative to shorter periods, and in dogs that had prior diagnostic imaging techniques. Univariable analyses indicated that risk was increased following prior treatment with several antimicrobial agents. However, on multivariable analysis, administration of fluoroquinolones was associated with increased risk but risk did not appear to increase following administration of other antimicrobials. These results can inform management of canine patients and infection control procedures to mitigate the risk of clinical disease due to MDR bacteria in hospitalized dogs.

Socioeconomic factors and antibiotic use in relation to antimicrobial resistance in the Amazonian area of Peru

Our objective was to correlate antibiotic resistance in gut E. coli flora of children, aged 6-72 months, with use of antibiotics, socioeconomic status (SES) and household characteristics in the urban communities of Yurimaguas and Moyobamba in the Amazonian area of Peru. Caregivers of 1598 children were interviewed using a structured questionnaire in a cross-sectional survey. Faecal samples were collected from the children and the antimicrobial susceptibility of E. coli was analysed by a rapid resistance screening method. Significantly higher odds for resistance were seen for children who had used antibiotics, both during the last 2 weeks and the last 6 months. Children from wealthier families had significantly higher odds for resistance to a number of antibiotics than children from the least wealthy families (Yurimaguas: nalidixic acid, OR = 2.13; ciprofloxacin, OR = 2.09; chloramphenicol, OR = 1.98. Moyobamba: nalidixic acid, OR = 1.59; ciprofloxacin, OR = 1.69). Thus, the children of wealthier families had a significantly increased odds ratio for resistance, also when controlling for the family's antibiotic use. Unknown factors related to socioeconomic status seem to contribute to the results seen in the study area.

Epidemiologically relevant antimicrobial resistance phenotypes in pathogens isolated from critically ill patients in a Brazilian Universitary Hospital

Antimicrobial resistance is a threat to public health worldwide and is associated with higher mortality and morbidity. Despite the extensive knowledge about this problem, drug resistance has continued to emerge, especially in intensive care units (ICUs). The objective of this study was to evaluate the frequencies of epidemiologically relevant resistance phenotypes in pathogens isolated from ventilator-associated pneumonia (VAP), bloodstream infections (BSI) and urinary tract infections (UTI) in patients admitted in the adult intensive care unit (AICU) of the Clinical Hospital of Federal University of Uberlândia, during an one year period. Additionally, at the period of the study, the antibiotic consumption in AICU was verified. Coagulase-negative staphylococci and S. aureus were the main agents of BSI (43.9%), with 60.0% of oxacilin-resistance for both microorganisms, Klebsiella-Enterobacter group predominated in UTI (23.4%), with resistance to third generation cephalosporins in 58.0% of the isolates; and, Pseudomonas aeruginosa in VAP (42.0%), with 72.0% of resistance to imipenem. Cephalosporins (49.6%), vancomycin (37.4%) and carbapenems (26.6%) were the most prescribed antibiotics in the unit. The comparison of the results with a publication of the NNIS program evidenced a worse situation in the studied hospital, mainly between Gram-negative, that had surpassed the percentile 90% elaborated by that system. Based on these results a reconsideration on the empirical use of antibiotics and on prevention and control of nosocomial infections practices is recommended.

Role of hospital stay and antibiotic use on Pseudomonas aeruginosa gastrointestinal colonization in hospitalized patients

The prospective cohort study presented here assessed the risk factors associated with Pseudomonas aeruginosa gastrointestinal colonization (PAGIC) in 933 patients hospitalized in five different wards in a French university hospital. A total of 195 patients were colonized. By logistic regression, hospitalization in an intensive care unit and length of hospital stay were independent risk factors. A significant association was observed between fluoroquinolone use and PAGIC caused by an ofloxacin-resistant strain (p < 0.0001), imipenem use and PAGIC caused by an imipenem-resistant strain (p < 0.0002) and ceftazidime use and PAGIC caused by a ceftazidime-resistant strain (p < 0.02). The ecological impact of antibiotic use is of great clinical relevance and clinicians should consider antimicrobial resistance in order to limit the development and dissemination of resistant microorganisms.

Clustering of antibiotic resistance of E. coli in couples: suggestion for a major role of conjugal transmission

Background

Spread of antibiotic resistance in hospitals is a well-known problem, but studies investigating the importance of factors potentially related to the spread of resistant bacteria in outpatients are sparse.

Methods

Stool samples were obtained from 206 healthy couples in a community setting in Southern Germany in 2002–2003. E. coli was cultured and minimal inhibition concentrations were tested. Prevalences of E. coli resistance to commonly prescribed antibiotics according to potential risk factors were ascertained.

Results

Prevalences of ampicillin resistance were 15.7% and 19.4% for women and men, respectively. About ten percent and 15% of all isolates were resistant to cotrimoxazole and doxycycline, respectively. A partner carrying resistance was the main risk factor for being colonized with resistant E. coli. Odds ratios (95% CI) for ampicillin and cotrimoxazole resistance given carriage of resistant isolates by the partner were 6.9 (3.1–15.5) and 3.3 (1.5–18.0), respectively.

Conclusion

Our data suggest that conjugal transmission may be more important for the spread of antibiotic resistance in the community setting than commonly suspected risk factors such as previous antibiotic intake or hospital contacts.

Quality improvement of surgical prophylaxis in Dutch hospitals: evaluation of a multi-site intervention by time series analysis

OBJECTIVES

Misuse of antibiotics in surgical prophylaxis is still quite common. The objectives of this study were to reduce the quantity and improve the quality of surgical prophylaxis and to reduce costs.

METHODS

Prospective multi-site study of elective procedures in 13 Dutch hospitals. The quality of prophylaxis was audited before and after an intervention consisting of performance feedback and implementation of national clinical practice guidelines. Process outcome parameters were antibiotic choice, duration, timing, antibiotic volume and costs. Segmented regression analysis was used to estimate the effect size of the intervention. Patient outcome was documented by the incidence of surgical site infections (SSI).

RESULTS

Before the intervention, 1763 procedures were recorded and 2050 thereafter. Antimicrobial use decreased from 121 to 79 DDD (defined daily doses)/100 procedures and costs reduced by 25% per procedure. After the intervention, antibiotic choice was inappropriate in only 37.5% of the cases instead of in 93.5% expected cases had the intervention not occurred. Prolonged prophylaxis was observed in 31.4% instead of 46.8% expected cases and inappropriate timing in 39.4% instead of the expected 51.8%. Time series analysis showed that all improvements were statistically significant (P < 0.01) and that they could be fully attributed to the intervention. The overall SSI rates before and after intervention were 5.4% (95% CI: 4.3-6.5) and 4.6% (95% CI: 3.6-5.4), respectively.

CONCLUSIONS

The intervention led to improved quality of surgical prophylaxis and to reduced antibiotic use and costs without impairment of patient outcome.