Vancomycin-resistant enterococci (VRE) are both of medical and public health importance associated with serious multidrug-resistant infections and persistent colonization. Enterococci are opportunistic environmental inhabitants with a remarkable adaptive capacity to evolve and transmit antimicrobial-resistant determinants. The VRE gene operons show distinct genetic variability and apparently continued evolution leading to a variety of antimicrobial resistance phenotypes and various environmental and livestock reservoirs for the most common van genes. Such complex diversity renders a number of important therapeutic options including "last resort antibiotics" ineffective and poses a particular challenge for clinical management. Enterococci resistance to glycopeptides and multidrug resistance warrants attention and continuous monitoring.

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Vancomycin-Resistant Enterococci: A Review of Antimicrobial Resistance Mechanisms and Perspectives of Human and Animal Health

Enterococcus is a significant pathogen in numerous infections, particularly in nosocomial infections, and is thus a great challenge to clinicians. Linezolid (LNZ), an oxazolidinone antibiotic, is an important therapeutic option for infections caused by Gram-positive bacterial pathogens, especially vancomycin-resistant enterococci. A systematic review was performed of the available literature on LNZ-resistant enterococci (LRE) to characterise these infections with respect to epidemiological, microbiological and clinical features. The results validated the potency of LNZ against enterococcal infections, with a sustained susceptibility rate of 99.8% in ZAAPS and 99.2% in LEADER surveillance programmes. Patients with LRE had been predominantly exposed to LNZ prior to isolation of LRE, with a mean treatment duration of 29.8 ± 48.8 days for Enterococcus faecalis and 23.1 ± 21.4 days for Enterococcus faecium. Paradoxically, LRE could also develop in patients without prior LNZ exposure. LNZ resistance was attributed to 23S rRNA (G2576T) mutations (51.2% of E. faecalis and 80.5% of E. faecium) as well as presence of the cfr gene (4.7% and 4.8%, respectively), which could transfer horizontally among the strains. In addition to the cfr gene, 32 cases of optrA-positive LRE were identified. Further study is required to determine the prevalence of novel resistance genes. The emergence of LRE thus hampers the treatment of such infections, which warrants worldwide surveillance.

The emerging problem of linezolid-resistant enterococci.

Vancomycin-resistant Enterococcus (VRE) is considered to be a major nosocomial pathogen that results in serious morbidity and mortality worldwide. Limited information is available concerning the prevalence of VRE infections in Iran. We carried out a systematic search by using different electronic databases including: Medline (via PubMed), Embase, Web of Science, and the Iranian Database. Meta-analysis was performed using comprehensive meta-analysis software. The meta-analyses revealed that the prevalence of VRE infections was 9.4 % (95 % confidence interval [95 % CI] 7.3–12) among culture-positive cases for Enterococcus species. The prevalence of VRE in Iran is compared with the results of developed countries. The prevalence of VRE in Germany, the United Kingdom (UK), and Italy was 11.2 %, 8.5–12.5 %, and 9 % respectively. Additionally, the frequency of vancomycin resistance among E. faecalis isolates was higher than for E. faecium. The results of this study indicate that a comprehensive infection control strategy based on hand hygiene, educating the hospital staff members, providing clinical guidance and principles for the appropriate use of antibiotics, sanitizing the hospitals, contact precautions, and active surveillance systems on the basis of international criteria is urgently needed.

Prevalence of vancomycin-resistant Enterococcus in Iran: a systematic review and meta-analysis

Background: Legionella species are ubiquitous and naturally found in lakes, rivers, streams and hot springs, and other water resources. The present study aimed to investigate the prevalence of Legionella species in water resources of Iran by a systematic review and meta-analysis.Methods: In search of papers relevant to the prevalence of Legionella in water resources of Iran, the scientific information database in both English and Persian languages was used. The search was limited to studies between the year 2000 and end of July 2016. Each cohort and cross-sectional study that reported the contamination of water with Legionella was included in the present study. For data analysis, comprehensive meta-analysis software with Cochran’s Q and I2 tests were used. P values less than 0.05 were considered statistically significant.Results: The prevalence of Legionella species in water resources of Iran was 27.3% (95% CI: 25.3-29.3). The prevalence of Legionella spp. in hospital water, dental settings water, and other water resources were 28.8% (95% CI: 26.4-31.2), 23.6% (95% CI: 16.1-33.2), and 29.6% (95% CI: 25.6-33.8), respectively. The most common Legionella species was L. pneumophila with a prevalence of 60.5% (95% CI: 53.3-67.2) and the prevalence of all other species was 52.5% (95% CI: 44.7-60.2). The highest prevalence was reported in Isfahan with 55.7% (95% CI: 48.0-63.0).Conclusion: Based on the results, the prevalence rate of Legionella species in water resources of Iran was high and the most common Legionella species was L. pneumophila.

https://ijms.sums.ac.ir/article_40575_97fcfbc3266153d99f2b589e78ceabae.pdf

Prevalence of Legionella Species in Water Resources of Iran: A Systematic Review and Meta-Analysis

Background: Nosocomial infection caused by non-Enterobacteriaceae gram negative bacteria (GNB-NE) is increasing in intensive care units (ICU). Aim: The objective of this study was to determine whether potable water in ICU wards at Tehran hospitals is contaminated with L. pneomophila, P. aeroginosa and Acinetobacter spp. Materials and Methods: A total of 52 water samples from shower bath and taps water in seven hospitals of Tehran were collected. The water sample concentrated by fi ltering through millipore cellulose fi lters and cultured on BCYE agar and tryptic soya agar media. The presence of Legionella pneumophila was confi rmed by real time PCR assay using primers-probe designed for the mip gene. Results: Legionella pneumophila, Pseudomonas aeroginosa and Acinetobacter were isolated from 5 (9.6%), 6 (11.4%) and 1 (1.8%) of the hospital water systems, respectively. This study demonstrated the presence of Legionella, Pseudomonas and Acinetobacter in water system in ICU wards of different hospitals in Tehran. Conclusions: Hot water from shower heads could be a potential source of infection for Legionella pneumophila. Water was also proved to contain Pseudomonas aeruginonsa, the main GNBNE causing nosocomila pneumonia at Tehran hospitals. Care should be taken concerning cleanliness and decontamination of water supplies at ICUs for pathogenic organisms.

Colonization of hospital water systems by Legionella pneumophila, Pseudomonas aeroginosa, and Acinetobacter in ICU wards of Tehran hospitals.

Background: Vancomycin-resistant enterococci pose an emerging health risk. The limitation in therapeutic options has resulted in the development of new drugs such as quinupristin/ dalfopristin and linezolid. Aim, Setting and Design: This study investigated the species prevalence and antibacterial resistance among enterococci isolated in selected Tehran hospitals. Materials and Methods: Between March 2006 and August 2007, 200 enterococcal isolates from urine, blood, stool and wound were recovered in 2 teaching hospitals of Tehran province. Susceptibility of all isolates was tested against vancomycin, teicoplanin and linezolid antibiotics by disk diffusion and agar dilution method. Results and Conclusion: Seventeen (8.5%), 6 (3%) and 4 (2%) of the isolates were resistant to vancomycin, teicoplanin and linezolid, respectively. Within the vancomycin-resistant isolates, 6 (35.2%), 4 (25%) and 1 (5.88%) showed vanA, vanB and vanC genotype patterns, respectively. Four (23.5%) of VRE isolates were resistant to linezolid with minimum inhibitory concentrations between 16 and 32 µg/mL. Two linezolid vancomycin resistant enterococci were E. faecium.

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Linezolid vancomycin resistant Enterococcus isolated from clinical samples in Tehran hospitals.

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Detection of Legionella in Hospital Water Supply using Mip Based Primers

Objectives Enterococci have gained attention during the past decade as important nosocomial pathogens. Their increasing prevalence has been paralleled by the occurrence of multidrug-resistant and high-level aminoglycoside-resistant strains. This study isolated Enterococcus spp. from hospital samples and determined their antibiotic resistance profile, focusing on aminoglycosides, and associated resistance mechanisms. Methods A total of 195 enterococci from hospital samples in Tehran were studied. Isolates were identified by biochemical reactions. Antimicrobial resistance was determined by disk diffusion. The vancomycin MIC for vancomycin-resistant isolates was determined by agar dilution. Detection of aminoglycoside resistance genes and intI1 and intI2 gene was performed by PCR. Results The majority of isolates were Enterococcus faecalis (65.1%), followed by Enterococcus faecium (31.8%), Enterococcus gallinarum (2.6%) and Enterococcus solitarius (0.5%). According to antibiogram results, 42.1% of isolates were high-level gentamicin-resistant (HLGR) and 40.5% were high-level streptomycin-resistant (HLSR). There was a high prevalence of aac(6')-Ie–aph(2")-Ia (96.3%) among HLGR isolates. ant(6)-Ia and aadA were identified in 93.7% and 64.6% of HLSR isolates, respectively. aph(2ʹʹ)-Ic was detected in 7 isolates (3.6%) and aph(2ʹʹ)-Ib in only 4 isolates (2.1%); no isolates harboured aph(2ʹʹ)-Id, intI1 or intI2. Conclusion Multidrug resistance was higher among HLGR and HLSR isolates compared with non-HLGR and non-HLSR isolates, which may result in limited treatment options. More than 50% of isolates were susceptible to aminoglycosides, thus correct identification in clinical laboratories and administration of these antibiotics can result in decreased used of antibiotics such as vancomycin and linezolid and help to reduce the emergence of resistance to these drugs.

R. Hosseini Doust

Papers

Linezolid vancomycin resistant Enterococcus isolated from clinical samples in Tehran hospitals.

Detection of Legionella in Hospital Water Supply using Mip Based Primers

High-level aminoglycoside resistance and distribution of aminoglycoside resistance genes among Enterococcus spp. clinical isolates in Tehran, Iran.

Inhibitory effects of probiotics on H. pylori by co-culture method.