Infections caused by naturally AmpC-producing Enterobacteriaceae: Can we use third-generation cephalosporins? A narrative review

Genomic Characterization of Carbapenemase-Producing Enterobacter hormaechei, Serratia marcescens, Citrobacter freundii, Providencia stuartii, and Morganella morganii Clinical Isolates from Bulgaria

Carbapenemase-producing Enterobacter spp. Serratia marcescens, Citrobacter freundii, Providencia spp., and Morganella morganii (CP-ESCPM) are increasingly identified as causative agents of nosocomial infections but are still not under systematic genomic surveillance. In this study, using a combination of whole-genome sequencing and conjugation experiments, we sought to elucidate the genomic characteristics and transferability of resistance genes in clinical CP-ESCPM isolates from Bulgaria. Among the 36 sequenced isolates, NDM-1 (12/36), VIM-4 (11/36), VIM-86 (8/36), and OXA-48 (7/36) carbapenemases were identified; two isolates carried both NDM-1 and VIM-86. The majority of carbapenemase genes were found on self-conjugative plasmids. IncL plasmids were responsible for the spread of OXA-48 among E. hormaechei, C. freundii, and S. marcescens. IncM2 plasmids were generally associated with the spread of NDM-1 in C. freundii and S. marcescens, and also of VIM-4 in C. freundii. IncC plasmids were involved in the spread of the recently described VIM-86 in P. stuartii isolates. IncC plasmids carrying blaNDM-1 and blaVIM-86 were observed too. blaNDM-1 was also detected on IncX3 in S. marcescens and on IncT plasmid in M. morganii. The significant resistance transfer rates we observed highlight the role of the ESCPM group as a reservoir of resistance determinants and stress the need for strengthening infection control measures.

Enterobacterales carrying chromosomal AmpC β-lactamases in Europe (EuESCPM): Epidemiology and antimicrobial resistance burden from a cohort of 27 hospitals, 2020-2022

INTRODUCTION

The ESCPM group (Enterobacter species including Klebsiella aerogenes - formerly Enterobacter aerogenes, Serratia species, Citrobacter freundii complex, Providencia species and Morganella morganii) has not yet been incorporated into systematic surveillance programs.

METHODS

We conducted a multicentre retrospective observational study analysing all ESCPM strains isolated from blood cultures in 27 European hospitals over a 3-year period (2020-2022). Diagnostic approach, epidemiology, and antimicrobial susceptibility were investigated.

RESULTS

Our study comprised 6,774 ESCPM isolates. MALDI-TOF coupled to mass spectrometry was the predominant technique for bacterial identification. Susceptibility to new β-lactam/β-lactamase inhibitor combinations and confirmation of AmpC overproduction were routinely tested in 33.3% and 29.6% of the centres, respectively. The most prevalent species were E. cloacae complex (44.8%) and S. marcescens (22.7%). Overall, third-generation cephalosporins (3GC), combined third- and fourth-generation cephalosporins (3GC + 4GC) and carbapenems resistance phenotypes were observed in 15.7%, 4.6%, and 9.5% of the isolates, respectively. AmpC overproduction was the most prevalent resistance mechanism detected (15.8%). Among carbapenemase-producers, carbapenemase type was provided in 44.4% of the isolates, VIM- (22.9%) and OXA-48-enzyme (16%) being the most frequently detected. E. cloacae complex, K. aerogenes and Providencia species exhibited the most notable cumulative antimicrobial resistance profiles, with the former displaying 3GC, combined 3GC + 4GC and carbapenems resistance phenotypes in 15.2%, 7.4%, and 12.8% of the isolates, respectively. K. aerogenes showed the highest rate of both 3GC resistant phenotype (29.8%) and AmpC overproduction (32.1%), while Providencia species those of both carbapenems resistance phenotype (42.7%) and carbapenemase production (29.4%). ESCPM isolates exhibiting both 3GC and combined 3GC + 4GC resistance phenotypes displayed high susceptibility to ceftazidime/avibactam (98.2% and 95.7%, respectively) and colistin (90.3% and 90.7%, respectively). Colistin emerged as the most active drug against ESCPM species (except those intrinsically resistant) displaying both carbapenems resistance phenotype (85.8%) and carbapenemase production (97.8%).

CONCLUSIONS

This study presented a current analysis of ESCPM species epidemiology in Europe, providing insights to inform current antibiotic treatments and guide strategies for antimicrobial stewardship and diagnostics.

Biodiversity of carbapenem-resistant bacteria in clinical samples from the Southwest Amazon region (Rondônia/Brazil)

Brazil is recognized for its biodiversity and the genetic variability of its organisms. This genetic variability becomes even more valuable when it is properly documented and accessible. Understanding bacterial diversity through molecular characterization is necessary as it can improve patient treatment, reduce the length of hospital stays and the selection of resistant bacteria, and generate data for health and epidemiological surveillance. In this sense, in this study, we aimed to understand the biodiversity and molecular epidemiology of carbapenem-resistant bacteria in clinical samples recovered in the state of Rondônia, located in the Southwest Amazon region. Retrospective data from the Central Public Health Laboratories (LACEN/RO) between 2018 and 2021 were analysed using the Laboratory Environment Manager Platform (GAL). Seventy-two species with carbapenem resistance profiles were identified, of which 25 species carried at least one gene encoding carbapenemases of classes A (blaKPC-like), B (blaNDM-like, blaSPM-like or blaVIM-like) and D (blaOXA-23-like, blaOXA-24-like, blaOXA-48-like, blaOXA-58-like or blaOXA-143-like), among which we will highlight Klebsiella pneumoniae, Pseudomonas aeruginosa, Acinetobacter baumannii, Serratia marcescens, and Providencia spp. With these results, we hope to contribute to the field by providing epidemiological molecular data for state surveillance on bacterial resistance and assisting in public policy decision-making.

Antibiotic definitive treatment in ventilator associated pneumonia caused by AmpC-producing Enterobacterales in critically ill patients: a prospective multicenter observational study

BACKGROUND

Ventilator associated pneumonia (VAP) due to wild-type AmpC-producing Enterobacterales (wtAE) is frequent in intensive care unit (ICU) patients. Despite a low level of evidence, definitive antimicrobial therapy (AMT) with third generation cephalosporins (3GCs) or piperacillin is discouraged.

METHODS

Observational prospective study including consecutive wtAE VAP patients in 20 French ICUs. The primary objective was to assess the association of the choice of definitive AMT, i.e. piperacillin ± tazobactam (PTZ), 3GCs or other molecule (4GCs, carbapenems, quinolones, cotrimoxazole; control group), with treatment success at day-7. Recurrence of infection was collected as a secondary outcome, and analyzed accounting for the competing risk of death.

RESULTS

From February 2021 to June 2022, 274 patients were included. Enterobacter cloacae was the most prevalent specie (31%). Seventy-eight patients (28%) had PTZ as definitive AMT while 44 (16%) had 3GCs and 152 (56%) were classified in the control group. Day-7 success rate was similar between the 3 groups (74% vs. 73% vs. 68% respectively, p = 0.814). Recurrence probability at day-28 was 31% (95% CI 21-42), 40% (95% CI 26-55) and 21% (95% CI 15-28) for PTZ, 3GCs and control groups (p = 0.020). In multivariable analysis, choice of definitive AMT was not associated with clinical success, but definitive AMT with 3GCs was associated with recurrence at day-28 [csHR(95%CI) 10.9 (1.92-61.91)].

CONCLUSION

Choice of definitive antimicrobial therapy was not associated with treatment success at day 7. However, recurrence of pneumonia at day-28 was higher in patients treated with third generation cephalosporins with no differences in mortality or mechanical ventilation duration.

Genomic analysis of a cAmpC (CMY-41)-producing Citrobacter freundii ST64 isolated from patient

Antibiotic resistance in Citrobacter freundii is a public health concern. This study evaluated the closed genome of a C. freundii isolated from the stool of a hospitalized patient initially related to a Salmonella outbreak. Confirmation of the isolate was determined by whole-genome sequencing. Nanopore sequencing was performed using a MinION with a Flongle flow cell. Assembly using SPAdes and Unicycler yielded a closed genome annotated by National Center for Biotechnology Information Prokaryotic Genome Annotation Pipeline. Genomic analyses employed MLST 2.0, ResFinder4.1, PlasmidFinder2.1, and VFanalyzer. Phylogenetic comparison utilized the Center for Food Safety and Applied Nutrition (CFSAN)-single nucleotide polymorphism pipeline and Genetic Algorithm for Rapid Likelihood Inference. Antimicrobial susceptibility was tested by broth microdilution following Clinical and Laboratory Standards Institute criteria. Multi-locus sequence type in silico analysis assigned the C. freundii as sequence type 64 and the blaCMY-41 gene was detected in resistome investigation. The susceptibility to antibiotics, determined using Sensititre® plates, revealed resistance to aztreonam, colistin, cefoxitin, amoxicillin/clavulanic acid, sulfisoxazole, ampicillin, and streptomycin. The genetic relatedness of the C. freundii CFSAN077772 with publicly available C. freundii genomes revealed a close relationship to a C. freundii SRR1186659, isolated in 2009 from human stool in Tanzania. In addition, C. freundii CFSAN077772 is nested in the same cluster with C. freundii clinical strains isolated in Denmark, Mexico, Myanmar, and Canada, suggesting a successful intercontinental spread.

Genomic analysis reveals the presence of emerging pathogenic Klebsiella lineages aboard the International Space Station

IMPORTANCE

The International Space Station (ISS) is a unique, hermetically sealed environment, subject to environmental pressures not encountered on Earth, including microgravity and radiation (cosmic ionising/UV). While bacteria's adaptability during spaceflight remains elusive, recent research suggests that it may be species and even clone-specific. Considering the documented spaceflight-induced suppression of the human immune system, a deper understanding of the genomics of potential human pathogens in space could shed light on species and lineages of medical astromicrobiological significance. In this study, we used hybrid assembly methods and comparative genomics to deliver a comprehensive genomic characterization of 10 Klebsiella isolates retrieved from the ISS. Our analysis unveiled that Klebsiella quasipneumoniae ST138 demonstrates both spatial and temporal persistence aboard the ISS, showing evidence of genomic divergence from its Earth-based ST138 lineage. Moreover, we characterized plasmids from Klebsiella species of ISS origin, which harbored genes for disinfectant resistance and enhanced thermotolerance, suggestin possible adaptive advantages. Furthermore, we identified a mobile genetic element containing a hypervirulence-associated locus belonging to a Klebsiella pneumoniae isolate of the "high-risk" ST101 clone. Our work provides insights into the adaptability and persistence of Klebsiella species during spaceflight, highlighting the importance of understanding the dynamics of potential pathogenic bacteria in such environments.

Antibiotic prophylaxis after 48 h postoperatively are not associated with decreased surgical site infections and other healthcare associated infections in pancreatic surgery patients: a retrospective cohort study

BACKGROUND

It is controversial whether antibiotic should be used prophylactically 48 h after pancreatic surgery. Hence, the association of antibiotic prophylaxis (AP) after 48 h postoperatively with the incidence of surgical site infections (SSIs) and other healthcare-associated infections (HAIs) in patients receiving pancreatic surgery was evaluated.

METHODS

A retrospective cohort analysis was performed on 1073 patients who underwent pancreatic surgery. These patients were categorized into the non-AP after 48 h postoperatively group (n = 963) and the AP after 48 h postoperatively group (n = 110) based on whether or not they obtained AP from 48 h to 30 days after surgery. Outcomes included SSIs and other HAIs.

RESULTS

The incidence of SSIs in the non-AP after 48 h postoperatively group (98/963, 10.2%) was notably lower than that in the AP after 48 h postoperatively group (22/110, 20.0%) (P = 0.002). Other HAIs incidence was not significantly different between the non-AP after 48 h postoperatively group (77/963, 8.0%) and the AP after 48 h postoperatively group (11/110, 10.0%) (P = 0.468). Multiple regression analysis demonstrated that AP after 48 h postoperatively was a risk factor for SSIs (OR = 2.14, 95% CI 1.28-3.59) but not for other HAIs (OR = 1.24, 95% CI 0.63-2.42) after adjustment for age, gender, and diabetes. Subsequent to adjustment for all confounding factors, AP after 48 h postoperatively was not a influence factor for SSIs (OR = 2.13, 95% CI 0.76-5.99) and other HAIs (OR = 3.69, 95% CI 0.99-13.81).

CONCLUSIONS

AP after 48 h postoperatively following pancreatic surgery was not associated with the lower morbidity rate of SSIs and other HAIs. Nonetheless, this study may facilitate further development of strategies towards standardization of the duration of AP management of pancreatic surgery.

Leveraging stewardship to promote ceftriaxone use in severe infections with low- and no-risk AmpC Enterobacterales

AmpC β-lactamases are associated with development of ceftriaxone resistance despite initial in vitro susceptibility, but the risk of AmpC derepression is not equal among Enterobacterales. The purpose of this study was to evaluate the impact of an AmpC stewardship intervention on the definitive treatment of low- and no-risk Enterobacterales. This was an IRB-approved, single pre-test, post-test quasi-experiment at a 5-hospital system. An AmpC stewardship intervention was implemented in July 2022 and included prescriber education, the removal of microbiology comments indicating potential for ceftriaxone resistance on therapy, and the modification of a blood PCR comment for Serratia marcescens to recommend ceftriaxone. Adults ≥18 years pre-intervention (July 2021 to December 2021) and post-intervention (July 2022 to December 2022) who received ≥72 hours of inpatient definitive therapy and had non-urine cultures growing low- and no-risk organisms (S. marcescens, Providencia spp., Citrobacter koseri, Citrobacter amalonaticus, or Morganella morganii) were included. The primary endpoint was definitive treatment with ceftriaxone. A total of 224 patients were included; 115 (51%) in pre-intervention and 109 (49%) in post-intervention. Definitive ceftriaxone therapy was prescribed more frequently after intervention [6 (5%) vs 72 (66%), P < 0.001]. After adjustment for critical illness, patients in the post-group were more likely to receive definitive ceftriaxone (adjOR, 34.7; 95% CI, 13.9-86.6). The proportion of patients requiring retreatment was 18 (15%) and 11 (10%) for pre- and post-intervention patients (P = 0.22), and ceftriaxone resistance within 30 days occurred in 5 (4%) and 2 (2%) patients in the pre- and post-group (P = 0.45). An antimicrobial stewardship intervention was associated with increased ceftriaxone prescribing and similar patient outcomes for low- and no-risk AmpC Enterobacterales.

Population-based study of Morganella-Proteus-Providencia group bloodstream infections

Background

There is a paucity of studies investigating the population-based epidemiology of Morganella-Proteus-Providencia (MPP) group infections. Our objective was to determine the incidence, risk factors, and outcome of MPP group bloodstream infections (BSI), and explore species-specific differences.

Methods

Population-based surveillance was conducted in the western interior of British Columbia, Canada, between April 1, 2010 and March 30, 2020.

Results

Sixty-two incident MPP group BSI occurred for an annual incidence of 3.4 per 100,000 residents; rates for Morganella morganii, Proteus mirabilis, and Providencia species were 0.5, 2.6, and 0.3 per 100,000 population, respectively. The median year of age was 72.5 and was different (p = 0.03) among the groups. Most (92%) MPP group BSIs were of community-onset. Significant differences were observed in the distribution of clinical focus of infection, with most notably 81% of P. mirabilis BSI due to genitourinary focus as compared to 60% and 22% for Providencia species and M. morganii, respectively. Comorbid illnesses that increased the risk for development of MPP group BSI (incidence rate ratio; 95% CI) were HIV infection (37.0; 4.4-139.6), dementia (11.5; 6.1-20.7), cancer (6.4; 3.2-11.9), stroke 6.5 (2.8-13.3), and diabetes 2.7 (1.3-5.0). Thirteen, one, and none of the cases with P. mirabilis, M. morganii, and Providencia species BSI died within 30 days of index culture for respective all cause case-fatalities of 27%, 11%, and 0% (p = 0.1).

Conclusions

Although collectively responsible for a substantial burden of illness, the epidemiology of MPP group BSI varies significantly by species.

SPILF update on bacterial arthritis in adults and children

In 2020 the French Society of Rhumatology (SFR) published an update of the 1990 recommendations for management of bacterial arthritis in adults. While we (French ID Society, SPILF) totally endorse this update, we wished to provide further information about specific antibiotic treatments. The present update focuses on antibiotics with good distribution in bone and joint. It is important to monitor their dosage, which should be maximized according to PK/PD parameters. Dosages proposed in this update are high, with the optimized mode of administration for intravenous betalactams (continuous or intermittent infusion). We give tools for the best dosage adaptation to conditions such as obesity or renal insufficiency. In case of enterobacter infection, with an antibiogram result "susceptible for high dosage", we recommend the requesting of specialized advice from an ID physician. More often than not, it is possible to prescribe antibiotics via the oral route as soon as blood cultures are sterile and clinical have symptoms shown improvement. Duration of antibiotic treatment is 6 weeks for Staphylococcus aureus, and 4 weeks for the other bacteria (except for Neisseria: 7 days).

A randomized clinical trial of antibiotic treatment duration in preterm premature rupture of membranes: 7 days vs until delivery

BACKGROUND

Antibiotic treatment in preterm premature rupture of membranes can prolong the interval from membrane rupture to delivery and improve neonatal outcomes. However, the duration of antibiotic treatment for preterm premature rupture of membranes has been rarely compared in prospective studies.

OBJECTIVE

This study aimed to investigate the optimal duration of antibiotic treatment for premature rupture of membranes. We performed a randomized controlled trial comparing neonatal morbidity and infantile neurologic outcomes between 2 groups of patients with preterm premature rupture of membranes who received antibiotic treatment for 7 days or until delivery, respectively.

STUDY DESIGN

This prospective randomized study included patients who were diagnosed with preterm premature rupture of membranes between 22+0 weeks and 33+6 weeks of gestation. The enrolled patients were randomly assigned to receive intravenous cefazolin (1 g dosage every 12 hours) and oral clarithromycin (500 mg dosage every 12 hours) either for 7 days or until delivery. The study protocol was registered at ClinicalTrials.gov under identifier NCT01503606. The primary outcome was a neonatal composite morbidity, and the secondary outcome was neurologic outcomes at 12 months of corrected age. We enrolled 151 patients and allocated 75 and 76 of them to the 7-day and until-delivery groups, respectively. Analysis was done by per protocol.

RESULTS

After excluding cases lost to follow-up and those with protocol violations, 63 (7-day regimen) and 61 (until-delivery regimen) patients with preterm premature rupture of membranes and their babies were compared. There was no significant difference in the pregnancy outcomes, including gestational age at delivery and the interval from rupture of membranes to delivery, between the 2 groups. Among the neonatal outcomes, bronchopulmonary dysplasia, intraventricular hemorrhage, retinopathy of prematurity, necrotizing enterocolitis, and proven neonatal sepsis did not differ between the groups. However, the rates of respiratory distress syndrome (32.8% vs 50.8%; P=.039) and composite neonatal morbidities (34.4% vs 53.9%; P=.026) were lower in the until-delivery group than in the 7-day group. This difference remained statistically significant after a multivariable analysis adjusting for maternal age, twin pregnancy, antenatal corticosteroids treatment, gestational age at delivery, interval from rupture of membranes to delivery, and clinical chorioamnionitis. Infantile neurologic outcomes were evaluated in 71.4% of the babies discharged alive and did not differ between the groups.

CONCLUSION

Overall, the until-delivery regimen of cefazolin and clarithromycin in preterm premature rupture of membranes led to a lower incidence of composite neonatal morbidity and respiratory distress syndrome than the 7-day regimen, and both regimens otherwise showed similar individual neonatal morbidities and infantile neurologic outcomes.

Prevalence and molecular characteristics of polymyxin-resistant Enterobacterales in a Chinese tertiary teaching hospital

Introduction

Polymyxin-resistant Enterobacterales poses a significant threat to public health globally, but its prevalence and genomic diversity within a sole hospital is less well known. In this study, the prevalence of polymyxin-resistant Enterobacterales in a Chinese teaching hospital was investigated with deciphering of their genetic determinants of drug resistance.

Methods

Polymyxin-resistant Enterobacterales isolates identified by matrix-assisted laser desorption were collected in Ruijin Hospital from May to December in 2021. Both the VITEK 2 Compact and broth dilution methods were used to determine polymyxin B (PMB) susceptibility. Polymyxin-resistant isolates were further characterized by molecular typing using PCR, multi-locus sequence typing, and sequencing of the whole genome.

Results

Of the 1,216 isolates collected, 32 (2.6%) across 12 wards were polymyxin-resistant (minimum inhibitory concentration (MIC) range, PMB 4-256 mg/ml, and colistin 4 ≥ 16 mg/ ml). A total of 28 (87.5%) of the polymyxin-resistant isolates had reduced susceptibility to imipenem and meropenem (MIC ≥ 16 mg/ml). Of the 32 patients, 15 patients received PMB treatment and 20 survived before discharge. The phylogenetic tree of these isolates showed they belonged to different clones and had multiple origins. The polymyxin-resistant Klebsiella pneumoniae isolates belonged to ST-11 (85.72%), ST-15 (10.71%), and ST-65 (3.57%), and the polymyxin-resistant Escherichia coli belonged to four different sequence types, namely, ST-69 (25.00%), ST-38 (25.00%), ST-648 (25.00%), and ST-1193 (25.00%). In addition, six mgrB specific mutations (snp_ALT c.323T>C and amino acid change p.Val8Ala) were identified in 15.6% (5/32) of the isolates. mcr-1, a plasmid-mediated polymyxin-resistant gene, was found in three isolates, and non-synonymous mutations including T157P, A246T, G53V, and I44L were also observed.

Discussion

In our study, a low prevalence of polymyxin-resistant Enterobacterales was observed, but these isolates were also identified as multidrug resistant. Therefore, efficient infection control measures should be implemented to prevent the further spread of resistance to last-line polymyxin therapy.

Clinical outcome of wild-type AmpC-producing Enterobacterales infection in critically ill patients treated with β-lactams: a prospective multicenter study

Background

β-lactams are the main antibiotics used against wild-type AmpC-producing Enterobacterales (wtAE). However, they may fail or select AmpC-overproducing mutants. Our aim was to assess factors associated with clinical failure of β-lactams in the treatment of wtAE infection.

Methods

From September 2017 to December 2020, we prospectively included all consecutive patients treated by definitive β-lactams therapy for wtAE infection in four university ICUs. Clinical failure was defined as inadequate response to antimicrobial therapy leading to death or to the switch for a broader-spectrum antibiotic.

Results

177 patients were included and 29.4% progressed to clinical failure. E. cloacae was the most prevalent species (42.4%) and ventilator-associated pneumonia (VAP) was the most frequent wtAE infection (69.5%). Cefepime and cefotaxime were used as definitive antibiotic treatment in 42.9% and 27.7% of patients, respectively. Occurrence of AmpC-overproduction was documented in 5.6% of patients and was associated with clinical failure (p = 0.004). In multivariate analysis, VAP (p < 0.001, OR 11.58 [95% CI 3.11–43.02] and K. aerogenes (p = 0.030, OR 3.76 [95% CI 1.13–12.46]) were independently associated with clinical failure. Conversely, cefotaxime as definitive treatment was found inversely associated with the risk of clinical failure (p = 0.022, OR 0.25 [95% CI 0.08–0.82]). After inverse probability weighting, cefotaxime showed a 20% risk reduction of clinical failure (95% CI  5–35%, p = 0.007) whatever the location of infection, the SOFA score on the day of wtAE infection, or the bacterial species.

Conclusions

Clinical failure in the treatment of wtAE infections is associated with the infection site and the causal microorganism. Additionally, cefotaxime use is probably protective against clinical failure in wtAE infection.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13613-022-01079-5.

Best practices: Appropriate use of the new β-lactam/β-lactamase inhibitor combinations, ceftazidime-avibactam and ceftolozane-tazobactam in South Africa

Antibiotic stewardship of hospital-acquired infections because of difficult-to-treat resistant (DTR) Gram-negative bacteria is a global challenge. Their increasing prevalence in South Africa has required a shift in prescribing in recent years towards colistin, an antibiotic of last resort. High toxicity levels and developing resistance to colistin are narrowing treatment options further. Recently, two new β-lactam/β-lactamase inhibitor combinations, ceftazidime-avibactam and ceftolozane-tazobactam were registered in South Africa, bringing hope of new options for management of these life-threatening infections. However, with increased use in the private sector, increasing levels of resistance to ceftazidime-avibactam are already being witnessed, putting their long-term viability as treatment options of last resort, in jeopardy. This review focuses on how these two vital new antibiotics should be stewarded within a framework that recognises the resistance mechanisms currently predominant in South Africa's multi-drug and DTR Gram-negative bacteria. Moreover, the withholding of their use for resistant infections that can be treated with currently available antibiotics is a critical part of stewardship, if these antibiotics are to be conserved in the long term.

Clinical Approach to Nosocomial Bacterial Sepsis

Bacterial sepsis and septic shock are associated with a high mortality, and when clinically suspected, clinicians must initiate broad-spectrum antimicrobials within the first hour of diagnosis. Thorough review of prior cultures involving multidrug-resistant (MDR) pathogens along with other likely pathogens should be performed to provide an appropriate broad-spectrum empiric antibiotic coverage. The appropriate antibiotic loading dose followed by individualized modification of maintenance dose should be implemented based on the presence of hepatic or renal dysfunction. Use of procalcitonin is no longer recommended to determine need for initial antibacterial therapy and for de-escalation. Daily reevaluation of appropriateness of treatment is necessary based on the culture results and clinical response. All positive cultures should be carefully screened for possible contamination or colonization, which may not represent the true organism causing the sepsis. Culture negative sepsis accounts for one-half of all cases, and de-escalation of initial antibiotic regimen should be done gradually in these patients with close monitoring.

Rapid Detection of Plasmid AmpC Beta-Lactamases by a Flow Cytometry Assay

Plasmidic AmpC (pAmpC) enzymes are responsible for the hydrolysis of extended-spectrum cephalosporins but they are not routinely investigated in many clinical laboratories. Phenotypic assays, currently the reference methods, are cumbersome and culture dependent. These methods compare the activity of cephalosporins with and without class C inhibitors and the results are provided in 24–48 h. Detection by molecular methods is quicker, but several genes should be investigated. A new assay for the rapid phenotypic detection of pAmpC enzymes of the Enterobacterales group-I (not usually AmpC producers) based on flow cytometry technology was developed and validated. The technology was evaluated in two sites: FASTinov, a spin-off of Porto University (Portugal) where the technology was developed, and the Microbiology Department of Ramón y Cajal University Hospital in Madrid (Spain). A total of 100 strains were phenotypically screened by disk diffusion for the pAmpC with the new 2 h assay. Molecular detection of the pAmpC genes was also performed on discrepant results. Forty-two percent of the strains were phenotypically classified as pAmpC producers using disk diffusion. The percentage of agreement of the flow cytometric assay was 93.0%, with 95.5% sensitivity and 91.1% specificity. Our proposed rapid assay based on flow cytometry technology can, in two hours, accurately detect pAmpC enzymes.

Does Protocatechuic Acid Affect the Activity of Commonly Used Antibiotics and Antifungals?

The aim of this study is to evaluate the efficiency of protocatechuic acid (PCA) in enhancing the commonly used drugs used to fight against nosocomial infection. These drugs are represented by routinely used antibiotics, synthetic chemotherapeutic agents with an antimicrobial spectrum, and antifungals. Three concentrations of PCA were added to 12 types of commercial disks used for antibiotic and antifungal susceptibility and tested against bacterial and yeast strains represented by Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Candida albicans. The results proved that PCA increased up to 50% of the antibacterial activity, especially that of levofloxacin against Staphylococcus aureus and Escherichia coli. These formulations will lead to new drug design ideas containing a smaller amount of antibiotics with the same effectiveness.

Morganella morganii, an Emerging Cause of Bloodstream Infections

Although recent reports of extensively antibiotic-resistant strains have highlighted the importance of Morganella morganii as an emerging pathogen, the epidemiology of serious infections due to this organism is not well defined. The objective of this study was to determine the incidence, determinants, and outcomes of Morganella morganii bloodstream infections (BSIs). Retrospective, population-based surveillance for Morganella morganii BSIs was conducted in Queensland, Australia, in 2000 to 2019; 709 cases were identified, for an annual incidence of 9.2 cases per million population. Most cases were of community onset, with 280 (39.5%) community-associated cases and 226 (31.9%) health care-associated cases. Morganella morganii BSIs were rare in children and young adults, and the incidence increased markedly with advancing age. The most common foci of infection were skin and soft tissue (131 cases [18.5%]), genitourinary (97 cases [13.7%]), and intraabdominal (90 cases [12.7%]). Most patients (580 cases [81.8%]) had at least one comorbid medical illness, with diabetes mellitus (250 cases [35.3%]), renal disease (208 cases [29.3%]), and congestive heart failure (167 cases [23.6%]) being most prevalent. Resistance to one or more of quinolones, co-trimoxazole, aminoglycosides, or carbapenems was observed in 67 cases (9.5%), and this did not change significantly over the study. The 30-day all-cause case fatality rate was 21.2%, and increasing age, nonfocal infection, heart failure, dementia, and cancer were independently associated with increased risk of death. Morganella morganii BSIs are increasing in our population, and elderly male subjects and individuals with comorbidities are at highest risk. Although antibiotic resistance is not a major contributor to the current burden in Queensland, ongoing surveillance is warranted. IMPORTANCE Recent reports of extensively antibiotic-resistant strains have highlighted the importance of Morganella morganii as an emerging pathogen. Despite its present and evolving importance as an agent of human disease, there is a limited body of literature detailing the epidemiology of serious infections due to Morganella morganii. Therefore, the objectives of this study were to examine the incidence and determinants of Morganella morganii BSIs and to examine risk factors for death in a large Australian population in 2000 to 2019.

Morganella morganii : An unusual analysis of 11 cases of pediatric urinary tract infections

Background

The increase in rare opportunistic microbial infections caused by Morganella morganii is alarming across the globe. It has been reported that in cases of urinary tract infections (UTIs) caused by M. morganii, however, few studies investigated children. Our study aimed to analyze the risk factors, antimicrobial susceptibility, and clinical characteristics, so as to improve the clinical diagnosis and therapy of M. morganii infection.

Methods

Between April 1, 2017 and April 1, 2021, 11 cases of pediatric UTIs caused by M. morganii were included in this retrospective study. Medical records were reviewed and analyzed.

Results

The study population included 10 males and one female between 11 months and 13 years old (mean age: 4 years 9 months). The most common comorbidity was nephrotic syndrome (72.7%, 8/11). Six patients (54.5%) were in the immunosuppressed state due to chemotherapy or immunosuppressant therapy. Ten cases defined as lower UTIs with no specific clinical manifestations had normal or slightly elevated leukocyte counts and procalcitonin (PCT) levels, and normal C‐reactive protein (CRP) levels. One child diagnosed upper UTIs accompanied with fever, high level of leukocyte counts, CRP, and PCT. The M. morganii presented 100% susceptibility to aztreonam, ertapenem, meropenem, piperacillin/tazobactam, cefepime, ceftazidime, cefotetan, ticarcillin/clavulanic acid, and cefoperazone/sulbactam. Almost all patients had good responses to third‐generation cephalosporins antibiotic therapy.

Conclusion

Clinical vigilance for the possibility of M. morganii in pediatric UTIs in combination with underlying disease or immunosuppression is warranted. Treatment strategies should be proposed according to the clinical condition and the antibiotic susceptibility results.

Impact of antibiotic susceptibility reporting on broad spectrum antibiotic use in serratia and morganella bacteremia

To minimize broad-spectrum antibiotic use, our microbiology laboratory changed antibiotic susceptibility reporting for AmpC-beta-lactamase producing Serratia marcescens and Morganella morganii in blood cultures to include results of narrow spectrum 3rd generation cephalosporins. We assessed the impact of this change on broad-spectrum antibiotic use and clinical outcomes. All adult patients with Serratia marcescens or Morganella morganii in blood culture 2 years pre- and post-change of susceptibility reporting were retrospectively reviewed. Exclusion: more than one pathogen isolated in their blood culture, did not receive antibiotics or died within 48 hours of positive blood culture. Outcomes: Rates of broad-spectrum antibiotic use, in-hospital mortality, clinical response and microbiologic success. There were 30 patients pre-change and 46 patients post-change of reporting. Cefepime use (broad-spectrum) decreased from 46.7% to 6.5% (p < 0.001) and 3^rd generation cephalosporin (narrow-spectrum) use increased (3.3% vs 34.8%, p = 0.0013) in the post-change cohort. This demonstrates the potential role of selective susceptibility reporting in antimicrobial stewardship.

Surging bloodstream infections and antimicrobial resistance during the first wave of COVID-19: a study in a large multihospital institution in the Paris region

Objectives

This study measured the impact of the first wave of COVID-19 pandemic (COVID-19) (March–April 2020) on the incidence of bloodstream infections (BSIs) at Assistance Publique – Hôpitaux de Paris (APHP), the largest multisite public healthcare institution in France.

Methods

The number of patient admission blood cultures (BCs) collected, number of positive BCs, and antibiotic resistance and consumption were analysed retrospectively for the first quarter of 2020, and also for the first quarter of 2019 for comparison, in 25 APHP hospitals (ca. 14 000 beds).

Results

Up to a fourth of patients admitted in March–April 2020 in these hospitals had COVID-19. The BSI rate per 100 admissions increased overall by 24% in March 2020 and 115% in April 2020, and separately for the major pathogens (Escherichia coli, Klebsiella pneumoniae, enterococci, Staphylococcus aureus, Pseudomonas aeruginosa, yeasts). A sharp increase in the rate of BSIs caused by microorganisms resistant to third-generation cephalosporins (3GC) was also observed in March–April 2020, particularly in K. pneumoniae, enterobacterial species naturally producing inducible AmpC (Enterobacter cloacae...), and P. aeruginosa. A concomitant increase in 3GC consumption occurred.

Conclusions

The COVID-19 pandemic had a strong impact on hospital management and also unfavourable effects on severe infections, antimicrobial resistance, and laboratory work diagnostics.

Three challenging cases of infections by multidrug-resistant Serratia marcescens in patients admitted to intensive care units

The occurrence of multidrug-resistant Serratia marcescens strains represents a serious public health threat. The purpose here is to report three cases of carbapenem-resistant S. marcescens infections with unfavorable clinical outcomes and provide a molecular description of the antibiotic resistance determinants at a genomic level. We performed bacterial identification by VITEK 2 and MALDI-TOF. The minimal inhibitory concentrations of antimicrobials were determined according to the Clinical and Laboratory Standards Institute guidelines, except for tigecycline, for which they were determined using Etest strips. Preliminary screening for the presence of carbapenemases was performed by ertapenem hydrolysis using MALDI-TOF MS. Whole-genome sequencing was provided to identify genes responsible for virulence and antimicrobial resistance. Here we report three challenging cases of S. marcescens that were resistant to the most commonly used antibiotics. Otherwise, we performed a genome description, which includes several genes involved in the resistance and virulence. These cases illustrate serious infection due to multidrug-resistant organisms and the complexity of treatment. Our results highlight the need to evaluate isolates regularly during long-term hospital stay to achieve optimal quality of clinical care and thus improve patient outcomes.

Difference in the Clinical Outcome of Bloodstream Infections Caused by Klebsiella aerogenes and Enterobacter cloacae Complex

Background

The difference in clinical outcomes between Klebsiella aerogenes (formerly Enterobacter aerogenes) bacteremia (KAB) and Enterobacter cloacae complex bacteremia (ECB) is controversial.

Methods

We compared the clinical outcomes of patients with KAB and ECB and examined the risk factors associated with mortality. We conducted a retrospective case-control study of hospitalized patients with monobacterial KAB and ECB between January 2011 and June 2020. The primary outcome measure was 30-day all-cause mortality. Multiple logistic regression and propensity-score (PS) matching were used to identify independent risk factors for mortality. The models included demographic characteristics, comorbidities, recent healthcare contact, patient status at the onset of bacteremia, and severity of infection as covariates.

Results

A total of 282 patients with KAB or ECB were included, among whom 194 patients were selected after PS matching. The 30-day all-cause mortality rate was higher in the ECB group than in the KAB group (24.1% vs 10.6%, P = .003). In a multivariable model, ECB was an independent risk factor for 30-day mortality in both overall and PS-matched cohorts (adjusted odds ratio, 3.528; 95% confidence interval, 1.614–7.714; P = .002). Stay in the intensive care unit at the onset of bacteremia and higher Pitt bacteremia score were found to be independent risk factors for 30-day mortality.

Conclusions

In our study, mortality was significantly higher in patients with ECB than in those with KAB. Further studies are warranted to clarify the virulence mechanisms of E cloacae complex.

Meropenem Versus Piperacillin-Tazobactam for Definitive Treatment of Bloodstream Infections Caused by AmpC β-Lactamase-Producing Enterobacter spp, Citrobacter freundii, Morganella morganii, Providencia spp, or Serratia marcescens: A Pilot Multicenter Randomized Controlled Trial (MERINO-2)

Background

Carbapenems are recommended treatment for serious infections caused by AmpC-producing gram-negative bacteria but can select for carbapenem resistance. Piperacillin-tazobactam may be a suitable alternative.

Methods

We enrolled adult patients with bloodstream infection due to chromosomal AmpC producers in a multicenter randomized controlled trial. Patients were assigned 1:1 to receive piperacillin-tazobactam 4.5 g every 6 hours or meropenem 1 g every 8 hours. The primary efficacy outcome was a composite of death, clinical failure, microbiological failure, and microbiological relapse at 30 days.

Results

Seventy-two patients underwent randomization and were included in the primary analysis population. Eleven of 38 patients (29%) randomized to piperacillin-tazobactam met the primary outcome compared with 7 of 34 patients (21%) in the meropenem group (risk difference, 8% [95% confidence interval {CI}, –12% to 28%]). Effects were consistent in an analysis of the per-protocol population. Within the subcomponents of the primary outcome, 5 of 38 (13%) experienced microbiological failure in the piperacillin-tazobactam group compared to 0 of 34 patients (0%) in the meropenem group (risk difference, 13% [95% CI, 2% to 24%]). In contrast, 0% vs 9% of microbiological relapses were seen in the piperacillin-tazobactam and meropenem arms, respectively. Susceptibility to piperacillin-tazobactam and meropenem using broth microdilution was found in 96.5% and 100% of isolates, respectively. The most common AmpC β-lactamase genes identified were bla_CMY-2, bla_DHA-17, bla_CMH-3, and bla_ACT-17. No ESBL, OXA, or other carbapenemase genes were identified.

Conclusions

Among patients with bloodstream infection due to AmpC producers, piperacillin-tazobactam may lead to more microbiological failures, although fewer microbiological relapses were seen.

Clinical Trials Registration

NCT02437045.

A highly specific Serratia-infecting T7-like phage inhibits biofilm formation in two different genera of the Enterobacteriaceae family

Due to the emergence of multidrug-resistant bacteria, bacteriophages have become a viable alternative in controlling bacterial growth or biofilm formation. Biofilm is formed by extracellular polymeric substances (EPS) and is one of the factors responsible for increasing bacterial resistance. Bacteriophages have been studied as a bacterial control agent by use of phage enzymes or due to their bactericidal activities. A specific phage against Serratia marcescens was isolated in this work and was evaluated its biological and genomic aspects. The object of this study was UFV01, a bacteriophage belonging to the Podoviridae family, genus Teseptimavirus (group of lytic viruses), specific to the species Serratia marcescens, which may be related to several amino acid substitutions in the virus tail fibers. Despite this high specificity, the phage reduced the biofilm formation of several Escherichia coli strains without infecting them. UFV01 presents a relationship with phages of the genus Teseptimavirus, although it does not infect any of the Escherichia coli strains evaluated, as these others do. All the characteristics make the phage an interesting alternative in biofilm control in hospital environments since small breaks in the biofilm matrix can lead to a complete collapse.

Comparison of outcomes in urinary tract infections caused by AmpC-harboring organisms treated with AmpC stable versus AmpC susceptible agents

There is minimal data on the optimal treatment of lower inoculum infections such as urinary tract infections (UTIs) caused by SPICE organisms which encode the betalactamase enzyme, AmpC. This single-center, retrospective review of adult hospitalized patients with UTIs caused by a SPICE organism compared outcomes amongst patients treated with drugs susceptible to AmpC hydrolysis versus drugs stable against AmpC. Of 156 patients, similar rates of clinical response, 30-day infection related readmission, 30-day infection recurrence, 30-day mortality rates, and median length of hospital stay were found between the two groups. Notably, 44% of patients with ceftriaxone resistance reported had recent β-lactam exposure versus only 11% of patients without ceftriaxone resistance (P = 0.002). Based on our data, there does not appear to be a difference in clinical response or any of the secondary outcomes in patients with UTIs treated with AmpC stable and AmpC susceptible agents.

Antimicrobial treatment of morganella morganii invasive infections: Systematic review

BACKGROUND

Morganella morganii is a Gram-negative, rod-shaped, facultative anaerobic bacillus divided into two subspecies, morganii and sibonii. Previously classified as Proteus morganii, it belongs to human gut commensal microbiota. Nevertheless, on rare occasions, especially in nosocomial and postoperative environment as well as in patients with the impaired immune system and young children, it may cause potentially fatal systemic infection.

OBJECTIVES

The aim of our systematic review was to determine whether and what invasive infections in humans were caused by Morganella morganii and to estimate outcomes of administered antibiotic management.

DATA SOURCES

This systematic review was registered at the PROSPERO database of systematic reviews and meta-analyses before initiation of the research (registration number CRD42020171919). Study eligibility criteria and participants. patients of any age and both sex harbouring Morganella morganii as the only microorganism in bodily fluids or tissues, from where it was isolated and identified by one or more of the following diagnostic methods: conventional techniques including colony morphology, Vitek 2, API or BD Phoenix biochemical systems, as well as more sophisticated methods, such as Matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS) and species-specific PCR for M. morganii.

METHODS AND INTERVENTIONS

We have systematically searched MEDLINE, EBSCO, SCOPUS, SCINDEX and GOOGLE SCHOLAR for case reports and case series with M. morganii invasive infections.

RESULTS

M. morganii can cause serious infections of different tissue in patients of any age. The most isolates were susceptible to ceftazidime, imipenem and amikacin. Majority of the patients completely recovered after antibiotic treatment. About 15% of the patients died despite of the therapy. Gentamicin was the most frequently used antibiotic in the treatment of infection caused by M. morganii.

CONCLUSION

M. morganii invasive infections should be taken into consideration by the clinicians, especially in hospital conditions, due to its high degree of mortality and high potential of this bacterium to develop multidrug resistance. Treatment of M. morganii infections should include gentamycin in combination with third generation cephalosporin or another antibiotic to which M. morganii is susceptible (after testing isolates for third cephalosporin generation for the production of AmpC β -lactamases).

Wide Distribution and Specific Resistance Pattern to Third-Generation Cephalosporins of Enterobacter cloacae Complex Members in Humans and in the Environment in Guadeloupe (French West Indies)

Species belonging to Enterobacter cloacae complex have been isolated in numerous environments and samples of various origins. They are also involved in opportunistic infections in plants, animals, and humans. Previous prospection in Guadeloupe (French West Indies) indicated a high frequency of E. cloacae complex strains resistant to third-generation cephalosporins (3GCs) in a local lizard population (Anolis marmoratus), but knowledge of the distribution and resistance of these strains in humans and the environment is limited. The aim of this study was to compare the distribution and antibiotic susceptibility pattern of E. cloacae complex members from different sources in a “one health” approach and to find possible explanations for the high level of resistance in non-human samples. E. cloacae complex strains were collected between January 2017 and the end of 2018 from anoles, farm animals, local fresh produce, water, and clinical human samples. Isolates were characterized by the heat-shock protein 60 gene-fragment typing method, and whole-genome sequencing was conducted on the most frequent clusters (i.e., C-VI and C-VIII). The prevalence of resistance to 3GCs was relatively high (56/346, 16.2%) in non-human samples. The associated resistance mechanism was related to an AmpC overproduction; however, in human samples, most of the resistant strains (40/62) produced an extended-spectrum beta-lactamase. No relation was found between resistance in isolates from wild anoles (35/168) and human activities. Specific core-genome phylogenetic analysis highlighted an important diversity in this bacterial population and no wide circulation among the different compartments. In our setting, the mutations responsible for resistance to 3GCs, especially in ampD, were diverse and not compartment specific. In conclusion, high levels of resistance in non-human E. cloacae complex isolates are probably due to environmental factors that favor the selection of these resistant strains, and this will be explored further.

Effects of gut microbiota remodeling on the dysbiosis induced by high fat diet in a mouse model of Gulf war illness

Gulf war illness (GWI) is a chronic disorder of unknown etiology characterized by multiple symptoms such as pain, fatigue, gastrointestinal disturbances and neurocognitive problems. Increasing evidence suggests that gut microbiome perturbations play a key role in the pathology of this disorder. GWI courses with gut microbiota alterations and their metabolites (e.g. short chain fatty acids -SCFA-), which can be aggravated by lifestyle risk factors such as a high fat diet (HF). To investigate the causative role of the gut microbiome, non-absorbable antibiotics (Abx) were administered to mice treated with GWI agents and concomitantly fed with a HF. In light of the wide use of Abx as pseudo-germ-free models, we evaluated the effects of Abx exposure on GWI and HF on body weight, food intake, gut microbiota changes and levels of the SCFA acetate. Results show that HF decreased food intake while increasing body weight in both controls and GWI. Exposure to Abx prevented these HF effects by offsetting the body weight gain in GWI. GWI and HF led to decreases in α-diversity, disruptions in the composition and structure of the gut bacterial community and decreases in acetate levels. This Abx-induced remodeling of the gut microbiome was characterized by an expansion of Proteobacteria, decreases in Bacteroidetes and Firmicutes, and overall increases in acetate levels, as well as by the proliferation of potential pathobionts. Therefore, the use of Abx may not represent a dependable approach to deplete the gut microbiome and its advantages as a pseudo germ-free model warrant further investigation.

Performance and impact of a multiplex PCR in ICU patients with ventilator-associated pneumonia or ventilated hospital-acquired pneumonia

BACKGROUND

Early appropriate antibiotic therapy reduces morbidity and mortality of severe pneumonia. However, the emergence of bacterial resistance requires the earliest use of antibiotics with the narrowest possible spectrum. The Unyvero Hospitalized Pneumonia (HPN, Curetis) test is a multiplex PCR (M-PCR) system detecting 21 bacteria and 19 resistance genes on respiratory samples within 5 h. We assessed the performance and the potential impact of the M-PCR on the antibiotic therapy of ICU patients.

METHODS

In this prospective study, we performed a M-PCR on bronchoalveolar lavage (BAL) or plugged telescoping catheter (PTC) samples of patients with ventilated HAP or VAP with Gram-negative bacilli or clustered Gram-positive cocci. This study was conducted in 3 ICUs in a French academic hospital: the medical and infectious diseases ICU, the surgical ICU, and the cardio-surgical ICU. A multidisciplinary expert panel simulated the antibiotic changes they would have made if the M-PCR results had been available.

RESULTS

We analyzed 95 clinical samples of ventilated HAP or VAP (72 BAL and 23 PTC) from 85 patients (62 males, median age 64 years). The median turnaround time of the M-PCR was 4.6 h (IQR 4.4-5). A total of 90/112 bacteria were detected by the M-PCR system with a global sensitivity of 80% (95% CI, 73-88%) and specificity of 99% (95% CI 99-100). The sensitivity was better for Gram-negative bacteria (90%) than for Gram-positive cocci (62%) (p = 0.005). Moreover, 5/8 extended-spectrum beta-lactamases (CTX-M gene) and 4/4 carbapenemases genes (3 NDM, one oxa-48) were detected. The M-PCR could have led to the earlier initiation of an effective antibiotic in 20/95 patients (21%) and to early de-escalation in 37 patients (39%) but could also have led to one (1%) inadequate antimicrobial therapy. Among 17 empiric antibiotic treatments with carbapenems, 10 could have been de-escalated in the following hours according to the M-PCR results. The M-PCR also led to 2 unexpected diagnosis of severe legionellosis confirmed by culture methods.

CONCLUSIONS

Our results suggest that the use of a M-PCR system for respiratory samples of patients with VAP and ventilated HAP could improve empirical antimicrobial therapy and reduce the use of broad-spectrum antibiotics.

Multicenter, Observational Cohort Study Evaluating Third-Generation Cephalosporin Therapy for Bloodstream Infections Secondary to Enterobacter, Serratia, and Citrobacter Species

OBJECTIVES

There is debate on whether the use of third-generation cephalosporins (3GC) increases the risk of clinical failure in bloodstream infections (BSIs) caused by chromosomally-mediated AmpC-producing Enterobacterales (CAE). This study evaluates the impact of definitive 3GC therapy versus other antibiotics on clinical outcomes in BSIs due to Enterobacter, Serratia, or Citrobacter species.

METHODS

This multicenter, retrospective cohort study evaluated adult hospitalized patients with BSIs secondary to Enterobacter, Serratia, or Citrobacter species from 1 January 2006 to 1 September 2014. Definitive 3GC therapy was compared to definitive therapy with other non-3GC antibiotics. Multivariable Cox proportional hazards regression evaluated the impact of definitive 3GC on overall treatment failure (OTF) as a composite of in-hospital mortality, 30-day hospital readmission, or 90-day reinfection.

RESULTS

A total of 381 patients from 18 institutions in the southeastern United States were enrolled. Common sources of BSIs were the urinary tract and central venous catheters (78 (20.5%) patients each). Definitive 3GC therapy was utilized in 65 (17.1%) patients. OTF occurred in 22/65 patients (33.9%) in the definitive 3GC group vs. 94/316 (29.8%) in the non-3GC group (p = 0.51). Individual components of OTF were comparable between groups. Risk of OTF was comparable with definitive 3GC therapy vs. definitive non-3GC therapy (aHR 0.93, 95% CI 0.51-1.72) in multivariable Cox proportional hazards regression analysis.

CONCLUSIONS

These outcomes suggest definitive 3GC therapy does not significantly alter the risk of poor clinical outcomes in the treatment of BSIs secondary to Enterobacter, Serratia, or Citrobacter species compared to other antimicrobial agents.

Screening of antibiotic resistance genes in pathogenic bacteria isolated from tiny freshwater shrimp (Macrobrachium lanchesteri) and "Kung Ten", the uncooked Thai food

Objective:

This study aimed to isolate and identify of pathogenic bacteria in tiny freshwater shrimp (Macrobrachium lanchesteri) and in Kung Ten, which is an unusual Thai cuisine that eaten alive shrimp directly. Antimicrobial susceptibility test and identification of antibiotic resistance genes for isolated bacteria were conducted.

Materials and Methods:

Eighty of fresh shrimp samples and forty of Kung Ten salads were collected from four fresh markets, which were located in Bangkok and Nonthaburi province (N = 120). The isolation, identification, and antimicrobial susceptibility test of pathogenic bacteria were done following the Clinical and Laboratory Standards Institute guidelines. Antibiotic-resistant bacteria were screened for β-lactamase relating genes, such as AmpC (MOX and ACC genes), bla_CTX-M, and Int1 genes.

Results:

The number of bacterial isolates in tiny freshwater shrimp and Kung Ten salad was 136 and 65, respectively. Aeromonas caviae, A. hydrophilla, Proteus penneri, Proteus vulgaris, and Klebsiella pneumoniae were commonly found. Ampicillin, amoxicillin/clavulanic, cefuroxime, tetracycline, and trimethoprim/sulfamethoxazole resistance were observed, and common antibiotic-resistant bacteria were A. caviae, P. vulgaris, Enterobacter Aerogenes, and K. pneumoniae. A. caviae, P. penneri, K. Pneumoniae, and A. hydrophilla were positive for MOX gene; bla_CTX-M, and Int1 genes; ACC and Int1 genes; and ACC gene, respectively.

Conclusion:

Raw or uncooked shrimps in Kung Ten salad may a risk in foodborne diseases due to positive for pathogenic bacterial isolates. However, hygienic control on food preparation is difficult to apply because of the difficulty of changing in local Thai food behavior.