Varying High Levels of Faecal Carriage of Extended-Spectrum Beta-Lactamase Producing Enterobacteriaceae in Rural Villages in Shandong,China: Implications for Global Health

Antibiotic resistance is considered a major threat to global health and is affected by many factors, of which antibiotic use is probably one of the more important. Other factors include hygiene, crowding and travel. The rapid resistance spread in Gram-negative bacteria, in particular extended-spectrum beta-lactamase (ESBL) producing Enterobacteriaceae (ESBL-E), is a global challenge, leading to increased mortality, morbidity and health systems costs worldwide. Knowledge about resistance in commensal flora is limited, including in China. Our aim was to establish the faecal carriage rates of ESBL-E and find its association with known and suspected risk factors in rural residents of all ages in three socio-economically different counties in the Shandong Province, China. Faecal samples and risk-factor information (questionnaire) were collected in 2012. ESBL-E carriage was screened using ChromID ESBL agar. Risk factors were analysed using standard statistical methods. Data from 1000 individuals from three counties and in total 18 villages showed a high and varying level of ESBL-E carriage. Overall, 42% were ESBL-E carriers. At county level the carriage rates were 49%, 45% and 31%, respectively, and when comparing individual villages (n = 18) the rate varied from 22% to 64%. The high level of ESBL-E carriage among rural residents in China is an indication of an exploding global challenge in the years to come as resistance spreads among bacteria and travels around the world with the movement of people and freight. A high carriage rate of ESBL-E increases the risk of infection with multi-resistant bacteria, and thus the need for usage of last resort antibiotics, such as carbapenems and colistin, in the treatment of common infections.     

Nosocomial Bloodstream Infections in Brazilian Pediatric Patients: Microbiology,Epidemiology, and Clinical Features

Background

Nosocomial bloodstream infections (nBSIs) are an important cause of morbidity and mortality and are the most frequent type of nosocomial infection in pediatric patients.

Methods

We identified the predominant pathogens and antimicrobial susceptibilities of nosocomial bloodstream isolates in pediatric patients (≤16 years of age) in the Brazilian Prospective Surveillance for nBSIs at 16 hospitals from 12 June 2007 to 31 March 2010 (Br SCOPE project).

Results

In our study a total of 2,563 cases of nBSI were reported by hospitals participating in the Br SCOPE project. Among these, 342 clinically significant episodes of BSI were identified in pediatric patients (≤16 years of age). Ninety-six percent of BSIs were monomicrobial. Gram-negative organisms caused 49.0% of these BSIs, Gram-positive organisms caused 42.6%, and fungi caused 8.4%. The most common pathogens were Coagulase-negative staphylococci (CoNS) (21.3%), Klebsiella spp. (15.7%), Staphylococcus aureus (10.6%), and Acinetobacter spp. (9.2%). The crude mortality was 21.6% (74 of 342). Forty-five percent of nBSIs occurred in a pediatric or neonatal intensive-care unit (ICU). The most frequent underlying conditions were malignancy, in 95 patients (27.8%). Among the potential factors predisposing patients to BSI, central venous catheters were the most frequent (66.4%). Methicillin resistance was detected in 37 S. aureus isolates (27.1%). Of the Klebsiella spp. isolates, 43.2% were resistant to ceftriaxone. Of the Acinetobacter spp. and Pseudomonas aeruginosa isolates, 42.9% and 21.4%, respectively, were resistant to imipenem.

Conclusions

In our multicenter study, we found a high mortality and a large proportion of gram-negative bacilli with elevated levels of resistance in pediatric patients.     

Epidemiology and Pathogenesis of Staphylococcus Bloodstream Infections in Humans: a Review

Staphylococci are among the most frequent human microbiota components associated with the high level of bloodstream infection (BSI) episodes. In predisposed patients, there is a high risk of transformation of BSI episodes to sepsis. Both bacterial and host factors are crucial for the outcomes of BSI and sepsis. The highest rates of BSI episodes were reported in Africa, where these infections were up to twice as high as the European rates. However, there remains a great need to analyze African data for comprehensive quantification of staphylococcal BSI prevalence. The lowest rates of BSI exist in Australia. Asian, European, and North American data showed similar frequency values. Worldwide analysis indicated that both Staphylococcus aureus and coagulase-negative staphylococci (CoNS) are the most frequent BSI agents. In the second group, the most prevalent species was Staphylococcus epidermidis, although CoNS were not identified at the species level in many studies. The lack of a significant worldwide decrease in BSI episodes indicates a great need to implement standardized diagnostic methods and research etiological factors using advanced genetic methods.     

Trends of Bloodstream Infections in a University Hospital During 12 Years

This study aims to investigate trends in bloodstream infections and their antimicrobial susceptibility profiles over 12 years in our hospital. This retrospective study was carried out in the Bursa Uludag University Hospital, Turkey, during 2008–2019. Blood cultures from patients were performed using BACTEC System. Isolates were identified with Phoenix System until 2018 and “matrix-assisted laser desorption ionization time-of-flight mass spectrometry” (MALDI-TOF MS) in 2019. Antibiotic susceptibility testing was performed with Phoenix System. Patient data came from the BD EpiCenter™ data management system. Escherichia coli was found to be the most common Gram-negative (11.6%), and coagulase-negative staphylococci were the most common Gram-positive (10.1%) monomicrobial growth. Overall, there was a significant increase in rates of extended-spectrum β-lactamase positive E. coli (p = 0.014) and Klebsiella pneumonia (p < 0.001), carbapenem-resistant E. coli (p < 0.001), and K. pneumoniae (p < 0.001) and colistin-resistant K. pneumoniae (p < 0.001) and Acinetobacter baumannii (p < 0.001) over 12 years. Carbapenem and colistin resistance has increased dramatically in recent years. We believe that regular monitoring of the distribution of pathogens and antibiotic susceptibility profiles, especially in intensive care units, can contribute to evidence for the increase in resistant microorganisms and help prevent their spread with antimicrobial stewardship and infection control policies.     

Microbiological Screening Is Necessary to Distinguish Carriers of Plasmid-Mediated AmpC Beta-Lactamase-Producing Enterobacteriaceae and Extended-Spectrum Beta-Lactamase (ESBL)-Producing Enterobacteriaceae because of Clinical Similarity

Objectives

Plasmid-mediated AmpC beta-lactamase-producing (pAmpC) Enterobacteriaceae are increasing worldwide, difficult to identify and often confounded with extended-spectrum beta-lactamase (ESBL) producers. The low prevalence precludes routine universal admission screening. Therefore, we evaluated potential risk factors for carriage of pAmpC-producing Enterobacteriaceae that would allow targeted screening to improve yield and reduce cost.

Patients and methods

We performed a case control study at a tertiary care center from 1/2006 to 12/2010. Cases were adult patients in whom pAmpC-producing Enterobacteriaceae were isolated; controls were chosen among carriers of ESBL-producing Enterobacteriaceae. Both infected and colonized patients were included.

Results

Over five years, we identified 40 pAmpC producers in 39 patients among 16,247 screened consecutive isolates of Enterobacteriaceae. The pAmpC prevalence was low (0.25%), but more than 30% of pAmpC carriers received incorrect empirical antibiotic treatment. When compared with 39 ESBL controls, pAmpC carriage was associated with clinically confirmed infections in 74% (versus 51%) (p=0.035), mainly of the urinary tract, previous antibiotic exposure in 63% (versus 36%) (p=0.035) and carriage of a nasogastric tube in 23% (versus 0%) (p=0.002). In the multivariate regression analysis only clinically confirmed infections remained significantly associated with pAmpC carriage (OR 1.44 (95%CI 1.15-2.57)). No other clinical and blood test-associated risk factor allowed discrimination of pAmpC-carrying patients from ESBL controls. The type of acquisition – nosocomial versus community-acquired – was also non-informative for resistance type, as 46% of pAmpC- and 44% of ESBL-producing Enterobacteriaceae were community-acquired.

Conclusions

This study could not identify a clinical profile that would allow targeted screening for pAmpC-producing Enterobacteriaceae when compared to ESBL carriers. Because empiric antimicrobial therapy was inappropriate in more than 30%, rapid identification of pAmpC carriers is needed. New microbiological methods are therefore required to simplify rapid and reliable detection of pAmpC carriers.     

Quinolone Resistance Mechanisms among Extended-Spectrum Beta-Lactamase (ESBL) Producing Escherichia coli Isolated from Rivers and Lakes in Switzerland

Sixty extended-spectrum β-lactamase (ESBL)-producing Escherichia coli isolated from rivers and lakes in Switzerland were screened for individual strains additionally exhibiting a reduced quinolone susceptibility phenotype. Totally, 42 such isolates were found and further characterized for their molecular (fluoro)quinolone resistance mechanisms. PCR and sequence analysis were performed to identify chromosomal mutations in the quinolone resistance-determining regions (QRDR) of gyrA, gyrB, parC and parE and to describe the occurrence of the following plasmid-mediated quinolone resistance genes: qepA, aac-6′-Ib-cr, qnrA, qnrB, qnrC, qnrD and qnrS. The contribution of efflux pumps to the resistance phenotype of selected strains was further determined by the broth microdilution method in the presence and absence of the efflux pump inhibitor phe-arg-β-naphthylamide (PAβN). Almost all strains, except two isolates, showed at least one mutation in the QRDR of gyrA. Ten strains showed only one mutation in gyrA, whereas thirty isolates exhibited up to four mutations in the QRDR of gyrA, parC and/or parE. No mutations were detected in gyrB. Most frequently the amino-acid substitution Ser83→Leu was detected in GyrA followed by Asp87→Asn in GyrA, Ser80→Ile in ParC, Glu84→Val in ParC and Ser458→Ala in ParE. Plasmid-mediated quinolone resistance mechanisms were found in twenty isolates bearing QnrS1 (4/20), AAC-6′-Ib-cr (15/20) and QepA (1/20) determinants, respectively. No qnrA, qnrB, qnrC and qnrD were found. In the presence of PAβN, the MICs of nalidixic acid were decreased 4- to 32-fold. (Fluoro) quinolone resistance is due to various mechanisms frequently associated with ESBL-production in E. coli from surface waters in Switzerland.     

Hospital Infections Caused by a Group of Recently Recognized Strains of Staphylococcus aureus

A survey was made of the phage-types of staphylococci responsible for cross-infection in a large veterans'' hospital between 1961 and 1964. An earlier survey had shown that in 1959 most of the infections were caused by staphylocci of the “80/81/82” group. In 1961 a new group of staphylococci were first recognized and provisionally designated as “Atypical Group III” strains; these were non-typable by the usual typing phages but showed inhibition patterns with some of the Group III phages. The “Atypical Group III” staphylococci all showed one or other of four patterns of multiple antibiotic resistance. By 1963 these resistant “Atypical Group III” staphylococci had become more frequent than “80/81/82” strains as causative agents of cross-infection, although both groups have continued to cause infections in the hospital. “Atypical Group III” strains mainly infected surgical wounds and skin ulcers, whereas “80/81/82” strains commonly produced primary skin sepsis, such as boils.     

Trends in Extended Spectrum Beta-Lactamase (ESBL) Producing Enterobacteriaceae and ESBL Genes in a Dutch Teaching Hospital,Measured in 5 Yearly Point Prevalence Surveys (2010-2014)

This paper describes the trends in prevalence of ESBL producing Enterobacteriaceae (ESBL-E) and ESBL genes, measured in five consecutive yearly Point Prevalence Surveys (PPS). All patients present in the hospital and in a day-care clinic (including patients on dialysis) on the day of the survey, were screened for perianal ESBL-E carriage. Perianal swabs were taken and cultured using an enrichment broth and a selective agar plate. Both phenotypic and genotypic methods were used to detect the production of ESBL, presence of ESBL-genes and clonal relatedness. Out of 2,695 patients, 135 (5.0%) were tested ESBL-E positive. The overall ESBL-E prevalence was stable over the years. Overall 5.2% of all ESBL-E were acquired by nosocomial transmission. A relative decrease of CTX-M-1-1-like ESBL genes (from 44 to 25%, p = 0.026) was observed, possibly related to the strong (>60%) decrease in antibiotic use in livestock in our country during the same period.     

Nosocomial Bloodstream Candida Infections in a Tertiary-Care Hospital in South Brazil: A 4-Year Survey

The aims of this study were to evaluate the epidemiology of nosocomial candidemia in a tertiary hospital in South Brazil and the in vitro antifungal susceptibility of isolates. Blood strains from 108 patients were identified by PCR-based method. Some 30.5 % of candidemia were caused by Candida tropicalis, 28.7 % were due to Candida albicans, 24.1 % with Candida parapsilosis sensu stricto, 8.3 % with Candida glabrata sensu lato, 1.8 % involved Candida krusei and 6.6 % with other species. Candidemia was more common in intensive care unit settings (66 %). In vitro susceptibility to antifungal drugs was determined by a microdilution method; and new species-specific clinical breakpoints for fluconazole and voriconazole were applied. Overall susceptibility rates were 100 % for itraconazole, 91 % for fluconazole, 98 % for voriconazole and 99 % for amphotericin B. Fluconazole resistance was mostly among C. parapsilosis sensu stricto isolates (26.9 %). Most of the findings reported here agreed with epidemiological features common to other tertiary hospitals in Brazil; but also revealed some peculiarities, such as a high frequency of C. tropicalis associated with candidemia. Besides, high rate of fluconazole resistance among C. parapsilosis stricto sensu isolates was obtained when applying the new species-specific clinical breakpoints.     

Characterization of Plasmid-Mediated Quinolone Resistance (PMQR) Genes in Extended-Spectrum β-Lactamase-Producing Enterobacteriaceae Pediatric Clinical Isolates in Mexico

This work describes the characterization of plasmid-mediated quinolone-resistance (PMQR) genes from a multicenter study of ESBL-producing Enterobacteriaceae pediatric clinical isolates in Mexico. The PMQR gene-positive isolates were characterized with respect to ESBLs, and mutations in the GyrA and ParC proteins were determined. The phylogenetic relationship was established by PFGE and the transfer of PMQR genes was determined by mating assays. The prevalence of the PMQR genes was 32.1%, and the rate of qnr-positive isolates was 15.1%; 93.3% of the latter were qnrB and 6.4% were qnrA1. The distribution of isolates in terms of bacterial species was as follows: 23.5% (4/17) corresponded to E. cloacae, 13.7% (7/51) to K. pneumoniae, and 13.6% (6/44) to E. coli. In addition, the prevalence of aac(6’)-Ib-cr and qepA was 15.1% and 1.7%, respectively. The molecular characteristics of qnr- and qepA-positive isolates pointed to extended-spectrum β-lactamase (ESBL) CTX-M-15 as the most prevalent one (70.5%), and to SHV-12 in the case of aac(6’)-Ib-cr-positive isolates. GyrA mutations at codons Ser-83 and Asp-87, and ParC mutations at codons Ser-80 were observed in 41.1% and 35.2% of the qnr-positive isolates, respectively. The analysis of the transconjugants revealed a co-transmission of bla_CTX-M-15 with the qnrB alleles. In general, the prevalence of PMQR genes (qnr and aac(6’)-Ib-cr) presented in this work was much lower in the pediatric isolates, in comparison to the adult isolates in Mexico. Also, ESBL CTX-M-15 was the main ESBL identified in the pediatric isolates, whereas in the adult ones, ESBLs corresponded to the CTX-M and the SHV families. In comparison with other studies, among the PMQR-genes identified in this study, the qnrB-alleles and the aac(6’)-Ib-cr gene were the most prevalent, whereas the qnrS1, qnrA1 and qnrB-like alleles were the most prevalent in China and Uruguay.     

Antimicrobial Resistance and Molecular Epidemiology of Escherichia coli Causing Bloodstream Infections in Three Hospitals in Shanghai,China

Escherichia coli (E. coli) is one of the most frequent and lethal causes of bloodstream infections (BSIs). We carried out a retrospective multicenter study on antimicrobial resistance and phylogenetic background of clinical E. coli isolates recovered from bloodstream in three hospitals in Shanghai. E. coli isolates causing BSIs were consecutively collected between Sept 2013 and Sept 2014. Ninety isolates randomly selected (30 from each hospital) were enrolled in the study. Antimicrobial susceptibility testing was performed by disk diffusion. PCR was used to detect antimicrobial resistance genes coding for β-lactamases (TEM, CTX-M, OXA, etc.), carbapenemases (IMP, VIM, KPC, NDM-1 and OXA-48), and phylogenetic groups. eBURST was applied for analysis of multi-locus sequence typing (MLST). The resistance rates for penicillins, second-generation cephalosporins, fluoroquinolone and tetracyclines were high (>60%). Sixty-one of the 90 (67.8%) strains enrolled produced ESBLs and no carbapenemases were found. Molecular analysis showed that CTX-M-15 (25/61), CTX-M-14 (18/61) and CTX-M-55 (9/61) were the most common ESBLs. Phylogenetic group B2 predominated (43.3%) and exhibited the highest rates of ESBLs production. ST131 (20/90) was the most common sequence type and almost assigned to phylogenetic group B2 (19/20). The following sequence types were ST405 (8/90) and ST69 (5/90). Among 61 ESBL-producers isolates, B2 (26, 42.6%) and ST131 (18, 29.5%) were also the most common phylogenetic group and sequence type. Genetic diversity showed no evidence suggesting a spread of these antimicrobial resistant isolates in the three hospitals. In order to provide more comprehensive and reliable epidemiological information for preventing further dissemination, well-designed and continuous surveillance with more hospitals participating was important.     

Epidemiology and Microbiology of Nosocomial Pediatric Candidemia at a Northern Indian Tertiary Care Hospital

The availability and aggressive use of chemotherapeutic and immunosuppressive agents as well as broad-spectrum antibacterial agents have created a large population of patients who are at increased risk of acquiring infections with fungal organisms, especially Candida species. Present work was undertaken to study the epidemiology and microbiology of candidemia and Candida colonization in hospitalized children. A total of 323 suspected cases of septicemia were enrolled, of which blood culture from 7.4% subjects was positive for Candida species. In total, 57.3% subjects were colonized by Candida species at least at one of the tested sites. Of 337 isolates, 24.3, 71.5, 2.9, 0.59, and 0.59% were Candida albicans, Candida tropicalis, Candida krusei, Candida kefyr, and Candida lusitaniae, respectively. Antifungal susceptibility results show that fluconazole, itraconazole, and amphotericin B resistance is prevalent in 18.2, 2.4, and 3.6% of C. albicans isolates, and 21.1, 4.6, and 0.04% of C. tropicalis isolates, respectively. In a large number of cases, source of blood infection was patient’s own colonizers, as shown by genetic matching. It was also noted that some strain types are circulating within the ward. High prevalence of non-albicans candidemia with high resistance to fluconazole is prevalent in North Indian hospitalized children.     

Risk Factors for Community-Acquired Urinary Tract Infections Caused by ESBL-Producing Enterobacteriaceae –A Case–Control Study in a Low Prevalence Country

Community-acquired urinary tract infection (CA-UTI) is the most common infection caused by extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae, but the clinical epidemiology of these infections in low prevalence countries is largely unknown. A population based case-control study was conducted to assess risk factors for CA-UTI caused by ESBL-producing E. coli or K. pneumoniae. The study was carried out in a source population in Eastern Norway, a country with a low prevalence of infections caused by ESBL-producing Enterobacteriaceae. The study population comprised 100 cases and 190 controls with CA-UTI caused by ESBL-producing and non-ESBL-producing E. coli or K. pneumoniae, respectively. The following independent risk factors of ESBL-positive UTIs were identified: Travel to Asia, The Middle East or Africa either during the past six weeks (Odds ratio (OR) = 21; 95% confidence interval (CI): 4.5–97) or during the past 6 weeks to 24 months (OR = 2.3; 95% CI: 1.1–4.4), recent use of fluoroquinolones (OR = 16; 95% CI: 3.2–80) and β-lactams (except mecillinam) (OR = 5.0; 95% CI: 2.1–12), diabetes mellitus (OR = 3.2; 95% CI: 1.0–11) and recreational freshwater swimming the past year (OR = 2.1; 95% CI: 1.0–4.0). Factors associated with decreased risk were increasing number of fish meals per week (OR = 0.68 per fish meal; 95% CI: 0.51–0.90) and age (OR = 0.89 per 5 year increase; 95% CI: 0.82–0.97). In conclusion, we have identified risk factors that elucidate mechanisms and routes for dissemination of ESBL-producing Enterobacteriaceae in a low prevalence country, which can be used to guide appropriate treatment of CA-UTI and targeted infection control measures.     

Identification and Antibiotic Susceptibility of Eggerthella Lenta in Bloodstream Infections

The identification and antibiotic susceptibility of two clinical isolates of Eggerthella lenta from bloodstream infections were determined. This microorganism is rarely pathogenic, and the findings are presented here to promote the detection and awareness of this infection. The bacteria were obtained from one patient with pressure sores and another with a malignant gastric tumor. Smears were prepared, stained, and examined by microscopy. Single colonies were analyzed by Gram staining, MALDI-TOF MS, and the 16S rRNA gene sequencing. Antibiotic sensitivity was assessed by the agar dilution method. The bacilli were found to be Gram-positive, and the MS results showed 99.8% homology with E. lenta. It was confirmed by gene sequencing. Antibiotic susceptibility tests demonstrated that E. lenta was sensitive to piperacillin-tazobactam, ampicillin-sulbactam, imipenem, meropenem, metronidazole, clindamycin, and vancomycin. This study could increase awareness of this rare infection. Open in a separate window     

Eradication of Methicillin-Resistant Staphylococcus aureus and of Enterobacteriaceae Expressing Extended-Spectrum Beta-Lactamases on a Model Pig Farm

Colonization of livestock with bacteria resistant to antibiotics is considered a risk for the entry of drug-resistant pathogens into the food chain. For this reason, there is a need for novel concepts to address the eradication of drug-resistant commensals on farms. In the present report, we evaluated the decontamination measures taken on a farm contaminated with methicillin-resistant Staphylococcus aureus (MRSA) and Enterobacteriaceae expressing extended-spectrum β-lactamases (ESBL-E). The decontamination process preceded the conversion from piglet breeding to gilt production. Microbiological surveillance showed that the decontamination measures eliminated the MRSA and ESBL-E strains that were detected on the farm before the complete removal of pigs, cleaning and disinfection of the stable, and construction of an additional stable meeting high-quality standards. After pig production was restarted, ESBL-E remained undetectable over 12 months, but MRSA was recovered from pigs and the environment within the first 2 days. However, spa (Staphylococcus aureus protein A gene) typing revealed acquisition of an MRSA strain (type t034) that had not been detected before decontamination. Interestingly, we observed that a farmworker who had been colonized with the prior MRSA strain (t2011) acquired the new strain (t034) after 2 months. In summary, this report demonstrates that decontamination protocols similar to those used here can lead to successful elimination of contaminating MRSA and ESBL-E in pigs and the stable environment. Nevertheless, decontamination protocols do not prevent the acquisition of new MRSA strains.     

Epidemiology of Invasive Fungal Infections in Patients with Acquired Immunodeficiency Syndrome at a Reference Hospital for Infectious Diseases in Brazil

Invasive fungal infections (IFIs) represent one of the main causes of morbimortality in immunocompromised patients. Pneumocystosis, cryptococcosis and histoplasmosis are the most frequently occurring IFIs in patients with acquired immunodeficiency syndrome (AIDS). Fungi, such as Candida spp. and Aspergillus spp., may cause severe diseases during the course of an HIV infection. Following the introduction of highly active anti-retroviral therapy, there has been a marked reduction of opportunistic fungal infections, which today is 20–25 % of the number of infections observed in the mid-1990s. This study is an observational and retrospective study aimed at the characterising IFI incidence and describing the epidemiology, clinical diagnostic and therapeutic features and denouement in HIV/AIDS patients. In HIV/AIDS patients, the IFI incidence is 54.3/1,000 hospitalisation/year, with a lethality of 37.7 %. Cryptococcosis represents the main opportunistic IFI in the population, followed by histoplasmosis. Nosocomial pathogenic yeast infections are caused principally by Candida spp., with a higher candidemia incidence at our institution compared to other Brazilian centres.