Antimicrobial susceptibility of clinical Enterobacteriaceae isolates at the emergency department in a regional hospital: A threat of extended spectrum beta-lactamase-producers among nursing home residents

Retrospective Analysis of Sensitivity Characteristics of Enterobacteriaceae: A Study Based on Specimen Types, Sex, and Age Bracket of Patients

Objective

Enterobacteriaceae have displayed widespread trends of antimicrobial resistance in recent years. Therefore, we aimed to analyse the antimicrobial susceptibility of common bacteria and explore the significance in treatment and research of infections induced by Enterobacteriaceae.

Methods

We retrospectively analysed 10,775 antimicrobial susceptibility test results acquired over a 6-year period in the affiliated hospital of Chengde Medical University. We divided the data based on specimen type (blood, sputum, pus, or urine), and population characteristics (age bracket and sex) for analysis. We mainly analysed the antimicrobial susceptibility of Escherichia coli (Eco), Klebsiella pneumoniae (Kpn), and Enterobacter cloacae (Ecl).

Results

In our study, it was found that the resistance rates of Eco, Kpn, and Ecl to most antimicrobial agents were significantly different (P < 0.05) on specimen type and age bracket. The Eco from sputum had the highest resistance rates except ciprofloxacin (CIP), levofloxacin (LVX), and gentamicin (GEN); the Kpn from urine had the highest resistance rates to all antimicrobial agents; the Ecl from urine had the highest resistance rates to most antimicrobial agents. The Eco from geriatric patients had the highest resistance rates except GEN and SXT; the Kpn from adult patients had the lowest resistance rates to most antimicrobial agents except LVX. The Eco isolated from males had higher resistance rates to most antimicrobial agents except CIP, LVX, and NIT than those isolated from females; the Kpn showed significant differences in antimicrobial susceptibility to only 5 out of 22 antimicrobial agents (P < 0.05); the Ecl showed significant differences in susceptibility only to two antimicrobial agents, LVX and TOB (P < 0.01).

Conclusion

The antimicrobial susceptibility of Enterobacteriaceae was significantly different among specimen type, age bracket and sex of patients, which is of great significance for the treatment and research of infection.

Epidemiology of extended-spectrum β-lactamases in Enterobacterales in Taiwan for over two decades

The emergence of antimicrobial resistance among microorganisms is a serious public health concern, and extended-spectrum β-lactamases (ESBL)-producing Enterobacterales is one of the major concerns among antibiotic-resistant bacteria. Although the prevalence of ESBL in Enterobacterales has been increasing with time, the prevalence of ESBL could differ according to the species, hospital allocation, sources of infections, nosocomial or community acquisitions, and geographic regions. Therefore, we conducted a comprehensive review of the epidemiology of ESBL-producing Enterobacterales in Taiwan. Overall, the rates of ESBL producers are higher in northern regions than in other parts of Taiwan. In addition, the genotypes of ESBL vary according to different Enterobacterales. SHV-type ESBLs (SHV-5 and SHV-12) were the major types of Enterobacter cloacae complex, but Serratia marcescens, Proteus mirabilis, Escherichia coli, and Klebsiella pneumoniae were more likely to possess CTX-M-type ESBLs (CTX-M-3 and CTX-M-14). Moreover, a clonal sequence type of O25b-ST131 has been emerging among urinary or bloodstream E. coli isolates in the community in Taiwan, and this clone was potentially associated with virulence, ESBL (CTX-M-15) production, ciprofloxacin resistance, and mortality. Finally, the evolution of the genetic traits of the ESBL-producing Enterobacterales isolates helps us confirm the interhospital and intrahospital clonal dissemination in several regions of Taiwan. In conclusion, continuous surveillance in the investigation of ESBL production among Enterobacterales is needed to establish its long-term epidemiology.

Microorganism Distributions and Antimicrobial Susceptibility in Community-Onset Bacteremia: A 6-Year Longitudinal Multicenter Cohort in Southern Taiwan

BACKGROUND

Prompt administration of appropriate antimicrobials has been correlated with improved prognoses in patients with bacteremia. Because the Clinical and Laboratory Standards Institute (CLSI) has numerously revised the interpretive criteria of susceptibility to numerous antimicrobials, the updated susceptibility is useful for empirical administration.

METHODS

In the multicenter retrospective cohort study consisting of adults with community-onset bacteremia in the emergency department (ED) during the period between January 2010 and December 2015, causative microorganisms were identified by the Vitek 2 system and prospectively collected. Antimicrobial susceptibility were respectively tested by the disk diffusion method for aerobes and the agar dilution method for anaerobes, in accordance with the contemporary CLSI criteria. Clinical information was retrospectively retrieved by reviewing the medical records.

RESULTS

Of the total 3,194 patients and 3,583 causative microorganisms, the leading source of bacteremia was the urinary tract infection (1,034 patients, 32.4%), and Escherichia coli accounted for the majority (1,332 isolates, 37.2%) of the total microorganisms. Overall, the lowest (58.2%) and highest (93.5%) susceptibility to cefazolin and piperacillin/tazobactam were, respectively, observed. In the leading five sources of bacteremia, in terms of the urinary tract infections, pneumonia, intraabdominal infections, skin and soft-tissue infections, and biliary tract infections, cefazolin or cefuroxime was only active against 49.3%-62.3% or 63.2%-74.1% of causative microorganisms, respectively. Notably, E. coli , Klebsiella species, and Proteus mirabilis (EKP) with the production of extended-spectrum beta-lactamases (ESBLs) accounted for 7.4% (142 isolates) of 1,908 EKP and 4.0% of all 3,583 microorganisms; and methicillin-resistant Staphylococcus aureus (MRSA) accounted for 37.7% (158 isolates) of S . aureus and 4.4% of all causative isolates.

CONCLUSIONS

For adults with community-onset bacteremia, a low incidence (approximate 4%) of ESBL-producing EKP and MRSA among all causative microorganisms, but low susceptibility to cefazolin and cefuroxime were recognized. To achieve favorable prognoses by prompt administration of appropriate antimicrobials in EDs, our findings might offer useful information for the antimicrobial stewardship program.

Risk factors and clinical impact of bacteremia due to carbapenem-nonsusceptible Enterobacteriaceae: A multicenter study in southern Taiwan

BACKGROUND

The emergence of carbapenem-non-susceptible Enterobacteriaceae (CnSE) infections is a public health threat. This study investigated the risk factors and clinical impact of bacteremia due to CnSE.

MATERIAL AND METHODS

The study was conducted at three hospitals in southern Taiwan between January 1, 2017, and October 31, 2019. Only the first episode of CnSE bacteremia from each adult was included. For one episode of CnSE bacteremia, two subsequent bacteremic episodes due to carbapenem-susceptible Enterobacteriaceae isolates in each hospital were included as the controls.

RESULTS

Among a total of 641 episodes of monomicrobial Enterobacteriaceae bacteremia were noted, 47 (7.3%) of which were of CnSE bacteremia. Ninety-four episodes of carbapenem-susceptible Enterobacteriaceae (CSE) bacteremia were selected as the controls for further analyses. In the multivariate analysis, hypertension (odds ratio [OR], 4.21; P = 0.005), Pitt bacteremia score (OR, 1.61; P = 0.002), and nosocomial bacteremia (OR, 3.30; P = 0.01) were associated with carbapenem nonsusceptibility among Enterobacteriaceae bacteremia. The most abundant CnSE isolate was Klebsiella pneumoniae (91.5%), followed by Klebsiella oxytoca (6.4%) and Escherichia coli (2.1%). Patients with CnSE bacteremia had a higher overall in-hospital mortality rate than those with CSE bacteremia (53.2% vs. 23.4%, P = 0.001). Moreover, in the multivariate analysis, the in-hospital mortality was significantly associated with higher Pitt bacteremia score (OR, 1.38; P = 0.02) and marginally associated with CnSE infections (OR, 2.44; P = 0.06).

CONCLUSION

Among adults with Enterobacteriaceae bacteremia, carbapenem nonsusceptibility, male sex, and the presence of hypertension or chronic kidney disease indicate a poor prognosis during hospitalization.

The prevalence and predictors of extended spectrum B-lactamase urinary tract infections among emergency department patients: A retrospective chart review

BACKGROUND AND IMPORTANCE

Inadequate initial antibiotic treatment of ESBL urinary tract infections (UTI) can lead to increase in the number of antibiotics used, return visits, longer hospitalizations, increased morbidity and mortality and increased costs. Given the important health implications on patients, this study aimed to examine the prevalence and predictors of ESBL UTIs among Emergency Department (ED) patients of a tertiary care center in Beirut, Lebanon.

DESIGN, SETTING AND PARTICIPANTS

Single-center retrospective observational study involving all adult UTI patients who presented to the ED of the American University of Beirut Medical Center, a tertiary care center between August 2019 and August 2020.

RESULTS

Out of the 886 patients that were included, 24.9% had an ESBL organism identified by urine culture. They had higher bladder catheter use within the previous 90 days, antibiotic use within last 90 days, and were more likely to have a history of an ESBL producing isolate from any body site in the last year. Antibiotic use in the last 90 days and a history of ESBL producing isolate at any site in the previous year were significantly associated with developing an ESBL UTI (OR = 1.66, p = 0.001 and OR = 2.53, p < 0.001 respectively). Patients diagnosed with cystitis were less likely to have an ESBL organism (OR = 0.4 95%CI [0.20-0.81], p = 0.01) CONCLUSION: The prevalence of ESBL organisms was found to be 24.9% in urinary tract infections. The predictors of an ESBL UTI infection were antibiotic use in the last 90 days, a history of ESBL producing isolate at any site in the previous year. Based on the findings of our study, we can consider modifying initial empiric antibiotic treatment for patients presenting with a UTI with the above stated risk factors.

Prevalence and Antibiotic Resistance of ESKAPE Pathogens Isolated in the Emergency Department of a Tertiary Care Teaching Hospital in Hungary: A 5-Year Retrospective Survey

Antibiotic treatments initiated on Emergency Departments (ED) are empirical. Therefore, knowledge of local susceptibility patterns is important. Despite this, data on expected pathogens and their resistance profile are scarce from EDs internationally. The study aim was to assess the epidemiology and resistance patterns of bacterial isolates from a tertiary-care ED over 5 years, focusing on ESKAPE bacteria (including the Enterobacterales group). After removal of duplicates, n = 6887 individual bacterial isolates were recovered, out of which n = 4974 (72.22%) were ESKAPE isolates. E. coli was the most frequent isolate (2193, 44.1%), followed by the Klebsiella genus (664; 13.4%). The third most frequent isolate was S. aureus (561, 11.3%). In total, multi-drug resistance (MDR) was present in 23.8% and was most prevalent in A. baumanii (65.5%), P. mirabilis (42.7%), and K. pneumoniae (32.6%). MRSA was isolated in 19.6%, while ESBL-producing Enterobacterales in 17.7%, and these were associated with remarkably higher resistance to other antibacterials as well. Difficult-to-treat resistance (DTR) was detected in 0.5%. The frequent isolation of some ESKAPE bacteria and the detected considerable acquired resistance among ED patients raise concern. The revealed data identified problematic pathogens and will guide us to set up the optimal empiric antibiotic protocol for clinicians.

The impact of inoculum size on the activity of cefoperazone-sulbactam against multidrug resistant organisms

OBJECTIVES

This study aims to assess the in vitro activity of cefoperazone alone and different cefoperazone-sulbactam ratios against different inoculum sizes of multidrug resistant organisms.

METHODS

Minimum inhibitory concentrations (MICs) of cefoperazone, cefoperazone-sulbactam at fixed ratio of 1:1 and 2:1 against a normal inoculum size of 5 × 10⁵ CFU/ml and a high inoculum size of 5 × 10⁷ CFU/ml were measured.

RESULTS

Each 33 isolates of extended-spectrum β-lactamases (ESBL)-producing Escherichia coli, ESBL-producing Klebsiella pneumoniae, carbapenem-resistant E. coli, and carbapenem-resistant Pseudomonas aeruginosa and a total of 122 isolates of carbapenem-resistant Acinetobacter baumannii were collected. After the addition of sulbactam at a 1:1 ratio, most MIC₅₀ and MIC₉₀ values decreased. Cefoperazone-sulbactam at a 1:1 ratio had a higher susceptibility rate against ESBL-producing E. coli, carbapenem-resistant E. coli, and carbapenem-resistant A. baumannii than cefoperazone-sulbactam at a 2:1 ratio (all P < 0.05). For ESBL-producing E. coli, the susceptibility rate of cefoperazone-sulbactam at ratios of (1:1) and (2:1) decreased from 97.0 to 87.9% and 90.9 to 60.6%, for normal to high inoculum, respectively. For ESBL-producing K. pneumoniae, both susceptibility rate of cefoperazone-sulbactam at ratios of (1:1) and (2:1) decreased from 75.8%, and 63.6% at normal inoculum to 51.5% and 42.4% at high inoculum.

CONCLUSIONS

Cefoperazone-sulbactam at a 1:1 ratio has greater in vitro activity against most multidrug resistant organisms than cefoperazone-sulbactam at a 2:1 ratio. Such combinations were not influenced by the inoculum size of ESBL-producing E. coli and K. pneumoniae and could be a therapeutic option for treating severe infections.

Presence of multidrug-resistant organisms in the residents and environments of long-term care facilities in Taiwan

OBJECTIVES

This study investigated the prevalence of multidrug-resistant organisms (MDROs) in the residents and environments of long-term care facilities (LTCFs) in Taiwan.

METHODS

We prospectively investigated the distribution of MDROs in residents of six LTCFs and their environments from January 2015 to December 2015 (intervention period). Active surveillance of colonization of MDROs was performed by culturing rectal and nasal swab samples every 3 months for the residents: 63, 79, and 73 in the first, second, and third surveillance investigations, respectively. If MDROs, including methicillin-resistant Staphylococcus aureus, carbapenem-resistant Enterobacteriaceae, carbapenem-resistant Pseudomonas aeruginosa, and MDR Acinetobacter baumannii were identified, then swab specimens from environmental sources were also collected and cultured. During the study period, several infection control measures were also implemented.

RESULTS

The overall infection density decreased significantly from 2.69 per 1000 patient-days in the preintervention (January 2014 to December 2014) to 2.39 per 1000 patient-days during the intervention period (p < 0.001). A total of 154 samples from residents and environmental sources were positive for MDROs. Methicillin-resistant S. aureus (n = 83, 53.9%) was the predominant organism, followed by carbapenem-resistant Enterobacteriaceae (n = 35, 22.7%), MDR A. baumannii (n = 30, 19.5%), and carbapenem-resistant P. aeruginosa (n = 6, 3.9%). The rates of detection of MDROs were 27.9% (60/215) in nasal swabs, 15.8% (34/215) in rectal swabs, and 11.1% (60/542) in the environmental sources.

CONCLUSIONS

The distribution and persistence of MDROs varied among the different LTCFs and time periods.

The Antimicrobial Susceptibility of Klebsiella pneumoniae from Community Settings in Taiwan, a Trend Analysis

Drug-resistant Klebsiella pneumoniae, especially extended-spectrum β-lactamase (ESBL)- and/or AmpC β-lactamase-producing strains, is an emerging problem worldwide. However, few data focusing on drug susceptibility of K. pneumoniae from community is available. In this study, we analyzed 1016 K. pneumoniae isolates from outpatients or those visiting emergency rooms collected during 2002–2012 from Taiwan Surveillance of Antimicrobial Resistance program. Significantly decreased susceptibilities to 3^rd generation cephalosporins and ciprofloxacin were found during the study period. By 2012, susceptibility to cefotaxime and ciprofloxacin was 83.6% and 81.6%, respectively. The prevalence of ESBL-producers increased from 4.8% in 2002 to 11.9% in 2012 (P = 0.012), while that of AmpC β-lactamase-producers increased from 0% to 9.5% in the same period (P < 0.001). Phylogenic analysis of the ESBL and AmpC-β-lactamase-producers by pulsed-field gel electrophoresis and multi-locus sequence typing revealed wide genetic diversity even among the most common sequence type 11 isolates (33.0%). By multivariate analysis, later study year, elderly, and urine isolates were associated with carriage of ESBL genes, while only urine isolates were associated with carriage of AmpC β-lactamase genes. Further studies are needed to determine which antibiotics are reasonable empirical therapy options for patients presenting with severe sepsis that might be caused by K. pneumoniae.

Laboratory investigation of a suspected outbreak caused by Providencia stuartii with intermediate resistance to imipenem at a long-term care facility

BACKGROUND

Providencia stuartii survives well in natural environment and often causes opportunistic infection in residents of long-term care facilities (LTCFs). Clinical isolates of P. stuartii are usually resistant to multiple antibiotics. The bacterium is also naturally resistant to colistin and tigecycline. Treatment of infections caused by carbapenem-resistant P. stuartii is challenging.

METHODS

During a 15-month period in 2013-2014, four isolates (P1, P2, and P3B/P3U) of P. stuartii showing intermediate resistance to imipenem were identified at a regional hospital in southern Taiwan. They were identified from three patients (P1-P3) transferred from the same LTCF for the treatment of the infection. Pulsed-field gel electrophoresis was used to genotype the isolates. Resistance genes/plasmids and outer membrane proteins were investigated by polymerase chain reaction and sequence analysis.

RESULTS

Isolates P1 and P3B/P3U demonstrated similar pulsotypes. All isolates were found to have resistance genes (bla_CMY-2, qnrD1, aac(6')-Ib-cr) carried on nonconjugative IncA/C plasmids of different sizes. A single point mutation was identified in the chromosomal gyrA (Ser83Ile) and parC (Ser84Ile) genes of all isolates. Various point mutations and insertion/deletion changes were found in their major outer membrane protein gene ompPst1.

CONCLUSIONS

Isolates of similar pulsotypes could appear after 15 months and caused urosepsis in another resident of the same LTCF. The bacterium may have persisted in the environment and caused opportunistic infection. As LTCF residents are usually vulnerable to infections, surveillance of multidrug-resistant organisms and infection control intervention that have been established in acute-care hospitals to control infections by resistant organisms are apparently as essential in LTCFs.