The Open Microbiology Journal




ISSN: 1874-2858 ― Volume 14, 2020
RESEARCH ARTICLE

Frequency of Iron Uptake Proteins Related Genes Among Klebsiella pneumoniae Isolates



Tahereh Elhaki1, 2, Ali Gheysarzadeh2, Nourkhoda Sadeghifard1, 2, *, Iraj Pakzad1, 2, Ava Behrouzi3, Morovat Taherikalani2, Farid A. Jalilian2, Mohsen Tabasi4, Reza Azizian1, 2
1 Department of Medical Microbiology, Medicine Faculty, Ilam University of Medical Science, Iran
2 Clinical Microbiology Research Center, Ilam University of Medical Sciences, Ilam, Iran
3 Department of Mycobacteriology and Pulmonary Research, Pasteur Institute of Iran, Tehran, Iran
4 Legal Medicine Research Center, Legal Medicine Organization, Tehran, Iran

Abstract

Aims:

The present study aimed to evaluate Iron uptake protein-related genes in clinical and environmental Klebsiella pneumoniae isolates.

Background:

Klebsiella pneumoniae as an opportunistic pathogen cause infections in immunocompromised patients. Iron uptake systems play an important role in the pathogenesis of Klebsiella pneumonia.

Objectives:

This study was designed to investigate the prevalence of iron uptake coding genes among isolates of Klebsiella pneumonia.

Materials and Methods:

A total of 300 isolates of Klebsiella pneumonia including 150 clinical isolates and 150 environmental isolates were selected. Finally, the frequency of iroN, iucD, kfuA,hmuR, and ybt [yHPI] genes were detected by PCR method.

Results:

The frequency of kfuA, iucD, iroN, yHPI in clinical isolates were 33.3%, 16.7%, 24.7%, 15.3%, respectively and these genes among environmental isolates were 20.7%, 6%, 49.3% and 0.7%, respectively. Among the clinical isolates, the most frequency genes were kfuA gene [50 isolates] and after that iroN [37 isolates], iucD [25 isolates] and yHPI [23 isolates], the genes with the most frequency among environmental isolates were iroN gene [74 isolates] and following that kfuA [31 isolates], iucD [9 isolates] and yHPI [1 isolate]. No hmuR positive samples among all clinical or environmental isolates were found.

Conclusion:

The result of this study showed that because of the high frequency of ferric iron system coding gene kfu among clinical isolates, this system might play an important role in the survival of bacteria against its host.

Keywords: : Klebsiella pneumoniae, Iron uptake gene, IroN, Iucd, Kfua, Hmur, Aybt, PCR.


Article Information


Identifiers and Pagination:

Year: 2020
Volume: 14
First Page: 107
Last Page: 112
Publisher Id: TOMICROJ-14-107
DOI: 10.2174/1874285802014010107

Article History:

Received Date: 17/02/2020
Revision Received Date: 13/04/2020
Acceptance Date: 13/04/2020
Electronic publication date: 21/05/2020
Collection year: 2020

© 2020 Elhaki et al.

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: (https://creativecommons.org/licenses/by/4.0/legalcode). This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.


* Address correspondence to this author at the Clinical Microbiology Research Center, Ilam University of Medical Sciences, Ilam, Iran. Tel: +98-8412227101, Fax: +98-8412227136, E-mail: sadeghifard@gmail.com





1. INTRODUCTION

Klebsiella pneumoniae is a gram-negative bacillus belonging to the Enterobacteriaceae family and, as an opportunistic pathogen can be found in water resources, soils and mucosal surfaces of mammals, as well as in the gastric, eye, respiratory and genital mucosa in humans [1Gheysarzadeh A, Pakzad I, Valadbeigi H, Maleki A, Sadeghifard N. Antimicrobial resistance and genetic analysis of multi-drug resistant Klebsiella pneumoniae isolates by pulsed-field gel electrophoresis. Gene Rep 2020; 100638., 2Martin RM, Bachman MA. Colonization, infection, and the accessory genome of Klebsiella pneumoniae. Front Cell Infect Microbiol 2018; 8: 4.
[http://dx.doi.org/10.3389/fcimb.2018.00004] [PMID: 29404282]
].

K. pneumoniae can be isolated from the upper respiratory tract and gastrointestinal tract in 5% of healthy people. This organism forms part of the normal microflora of the human body; about one-third of people are intestinal carriers of this microbe [2Martin RM, Bachman MA. Colonization, infection, and the accessory genome of Klebsiella pneumoniae. Front Cell Infect Microbiol 2018; 8: 4.
[http://dx.doi.org/10.3389/fcimb.2018.00004] [PMID: 29404282]
, 3Navon-Venezia S, Kondratyeva K, Carattoli A. Klebsiella pneumoniae: A major worldwide source and shuttle for antibiotic resistance. FEMS Microbiol Rev 2017; 41(3): 252-75.
[http://dx.doi.org/10.1093/femsre/fux013] [PMID: 28521338]
]. K. pneumoniae is one of the causes of nosocomial infections; the colonization of this bacterium in hospitalized patients is more than outpatient reportedly. K. pneumoniae is an etiology of a wide range of infections including septicemia, pneumonia, Urinary Tract Infection (UTI), meningitis, and purulent abscesses in various organs, especially liver abscesses, Surgical Site Infection (SSI) and conjunctivitis [4Chang W-N, Lu C-H, Huang C-R, Chuang Y-C, Tsai N-W, Chang C-C, et al. Clinical characteristics of post-neurosurgical Klebsiella pneumoniae meningitis in adults and a clinical comparison to the spontaneous form in a Taiwanese population. 2010; 17(3): 334-8.
[http://dx.doi.org/10.1016/j.jocn.2009.06.019]
]. This bacterium occasionally causes UTI and bacteremia along with localized damage in patients with immunodeficiency and catheter [5Chakma S, Majumdar T, Singh NB. Study of opportunistic pathogens in lower respiratory tract infections among subjects with acquired immune deficiency syndrome [aids] in a tertiary care centre of Tripura. Chart 2017; 12: 14.]. K. pneumoniae accounts for about 1% of bacterial pneumonia and can cause the production of necrotic dense and hemorrhagic centers in the lung [6Lee IK, Liu J-W, Yang KD. Fatal dengue hemorrhagic fever in adults: Emphasizing the evolutionary pre-fatal clinical and laboratory manifestations. PLoS Negl Trop Dis 2012; 6(2): e1532.
[http://dx.doi.org/10.1371/journal.pntd.0001532] [PMID: 22363829]
, 7Clegg S, Murphy CN. Epidemiology and virulence of Klebsiella pneumoniae In: Urinary Tract Infections: Molecular Pathogenesis and Clinical Management. 2017; 435-57.
[http://dx.doi.org/10.1128/9781555817404.ch18]
]. The most important virulence factors known in K. pneumoniae include polysaccharide capsules [77 serotypes], lipopolysaccharides (8 serotypes), adhesins and the iron uptake system [8Lai Y-C, Yang S-L, Peng H-L, Chang H-YJI. Identification of genes present specifically in a virulent strain of Klebsiella pneumoniae. 2000; 68(12): 7149-51.]. The iron uptake system, behind the capsule, is the second most important virulence factor in K. pneumoniae [9Koczura R, Kaznowski A. Occurrence of the Yersinia high-pathogenicity island and iron uptake systems in clinical isolates of Klebsiella pneumoniae. Microb Pathog 2003; 35(5): 197-202.
[http://dx.doi.org/10.1016/S0882-4010(03)00125-6] [PMID: 14521878]
]. The bacterial growth is inhibited in the host body not only by host defense mechanisms but also by available iron stores. Iron is an essential factor in bacterial growth, whose uptake is essential for the survival of pathogenic bacteria in the host body [10Winkelmann G. Specificity of iron transport in bacteria and fungi Handbook of Microbial Iron Chelates [1991] 2017; 65-106.]. The iron is beneficial in the nutrition and growth of bacteria and is also a vital cofactor in defense enzymes against oxidative stresses, such as the components of superoxide dismutase, catalase, and peroxidase [11Vila A, Cassata A, Pagella H, Amadio C, Yeh K-M, Chang F-Y, et al. Appearance of Klebsiella pneumoniae liver abscess syndrome in Argentina: case report and review of molecular mechanisms of pathogenesis. 2011; 5: 107.
[http://dx.doi.org/10.2174/1874285801105010107]
, 12Pilo F, Angelucci E. A storm in the niche: Iron, oxidative stress and haemopoiesis. Blood Rev 2018; 32(1): 29-35.
[http://dx.doi.org/10.1016/j.blre.2017.08.005] [PMID: 28847531]
]. Since this element is bonded to extracellular proteins such as hemoglobin, myoglobin, hemosiderin, ferritin and also proteins with high affinity for iron such as lactoferrin and transferrin, so the iron stores available for bacteria are limited, as well as free iron (10-18 mol) level is several thousand times less than the level required for bacterial growth. The bacterium absorbs iron, either directly or by secretion of molecules with high affinity, low molecular weight and iron-chelating agent, known as siderophores that can bind with iron-binding proteins of the host [13Moranta Mesquida D, Regueiro V, March C, Llobet E, Margareto J, Larrarte E, et al. Klebsiella pneumoniae capsule polysaccharide impedes the expression of beta-defensins by airway epithelial cells. 2018., 14Ellermann M, Arthur JC. Siderophore-mediated iron acquisition and modulation of host-bacterial interactions. Free Radic Biol Med 2017; 105: 68-78.
[http://dx.doi.org/10.1016/j.freeradbiomed.2016.10.489] [PMID: 27780750]
]. The synthesized and secreted siderophores are capable of binding to ferric iron with an affinity about 10 times higher than transferrin or lactoferrin. Under different conditions of the host body, K. pneumoniae can synthesize various species of siderophores, and the most important type is Enterobactin, often known as Enterochelin. The siderophore seems to be the largest iron uptake system synthesized by this bacterium [15Tu Y-C, Lu M-C, Chiang M-K, Huang S-P, Peng H-L, Chang H-Y, et al. Genetic requirements for Klebsiella pneumoniae-induced liver abscess in an oral infection model 2009.
[http://dx.doi.org/10.1128/IAI.01523-08]
]. Other siderophores produced by K. pneumoniae include aerobactin, ferrichrome, ferric citrate, salmochelin, yersiniabactin, heme, ferric iron and siderophores necessary for ferrous (two systems) uptake. Ten iron uptake systems have been known so far in K. pneumoniae; however, six iron uptake systems have been observed in non-pathogenic species of K. pneumoniae and ten iron uptake systems in invasive isolates, especially isolates producing liver abscesses [11Vila A, Cassata A, Pagella H, Amadio C, Yeh K-M, Chang F-Y, et al. Appearance of Klebsiella pneumoniae liver abscess syndrome in Argentina: case report and review of molecular mechanisms of pathogenesis. 2011; 5: 107.
[http://dx.doi.org/10.2174/1874285801105010107]
].

The genes encoding iron uptake system in K. pneumoniae include fhuA (ferrichrome), iucABCD and iutA (aerobactin), fepAB and entAB (enterobactin), fecAE (ferric citrate), iroNB (salmochelin), hmuR (heme), sitA and feo (ferrous, Fe2+), kfu ABC (ferric, Fe3+), fyuA and irp-1, irp-2, ybtS and yersiniaHPI (yersiniabactin) [16Dogan O, Vatansever C, Atac N, Albayrak O, Karahuseyinoglu S, Sahin OE, et al. The role of iron uptake systems in the pathogenesis of colistin-resistant hypervirulent K. pneumoniae infections. bioRxiv 2019; 677492., 17Smith AT, Sestok AE. Expression and purification of functionally active ferrous iron transporter FeoB from Klebsiella pneumoniae. Protein Expr Purif 2018; 142: 1-7.
[http://dx.doi.org/10.1016/j.pep.2017.09.007] [PMID: 28941825]
]. Despite the epidemiological importance of K. pneumoniae, limited studies have been carried out on the importance of iron uptake systems in the pathogenicity of this species. Considering the importance of the iron uptake system, behind the bacterial capsule structure, as a virulence factor in K. pneumoniae, and due to the significance of diseases caused by K. pneumoniae as an opportunistic pathogen, the present study compared the genes involved in iron uptake and their prevalence among environmental and clinical isolates of K. pneumoniae aiming to determine the active role of these genes in the pathogenicity of this bacterium.

2. MATERIALS AND METHODS

2.1. Organism Collection

A total of 150 clinical and 150 environmental isolates were involved in this study. Clinical isolates were collected through October.2014 – December.2016 from Ilam hospitals and Clinical Laboratories. Environmental isolates were gathered through April 2015- December.2016 from the sewage of Ilam. In 30 times of sampling, 600 samples were collected from sewage. With regard to the fluency of sewage, sampling was performed within 5 minutes. The volume of sewage was almost 1.5 liter in every/each sampling. To avoid collecting the same source of bacteria, sampling from sewage was performed twice a month. All clinical and environmental samples were identified by biochemical tests such as Simon citrate, TSI, SH2, SIM, MR-VP, Urease, and Lysine Iron Agar.

The current study was performed based on the ethical standards Declaration of Helsinki and all individuals provided written informed consent that was approved by the Ethics Committee of The Ilam University of Medical Sciences

2.2. DNA Extraction

The suspension was prepared by LB broth and incubated at 37C˚ for 18-24h. The samples were then centrifuged at 3500 rpm for 10 min and the pellet used for extraction. PCR was done to investigate iucD, iroN, kfuA, hmuR and yHPI. Primer is mentioned in Table 1. PCR reaction was in 25µl and 3µl of primers added to Master Mix.

2.3. Statistical Analysis

Data analysis was performed by using SPSS software version 19.0 for windows [IBM, Chicago, IL, USA]. A chi-square test was used to compare the prevalence of iron uptake coding genes among clinical and environmental isolates of Klebsiella pneumonia. A p-value < 0.05 was considered as statistically significant.

3. RESULTS

The frequency of kfuA, iroN, iucD and yHPI among clinical isolates were 33.3%, 24.7%, 16.7%, and 15.3%m respectively, additionally, the frequency of these genes among environmental isolates was 20.7%, 49.3%, 6%, and 0.7%, respectively. hmuR was neither detected in clinical nor in environmental isolates (Table 2). As indicated in Table 2, there is a significant difference between the frequency of kfuA gene two groups of Study (P=0.016). In this study, it was found that some isolates had more than one iron uptake-related gene. Based on the results of identifying the genes, 18.6% (28 isolates) of the clinical isolates and 9.33% of the environmental isolates had two iron uptake-related genes and 6% among the clinical isolates, and 2% of the environmental isolates had three iron uptake-related genes. In addition, 35.33% of the clinical samples and 46.66% of the clinical samples had only one iron uptake-related gene (Table 2).

In this study, the clinical isolates with two iron uptake-related genes were classified into six groups, including aerobactin-yersiniabactin-positive isolates (n=2), salmochelin-aerobactin-positive isolate (n=1), salmochelin-ferric iron-positive isolates (n=10), ferric iron – Yersiniabactin-positive isolates (n=2), aerobactin - ferric iron-positive isolates (n=9) and yersiniabactin – salmochelin-positive isolates (n=4). The environmental isolates were classified into three groups, including salmochelin - ferric iron isolates (n=11), salmochelin - aerobactin isolates (n=2) and salmochelin - yersiniabactin isolate (n=1). In the clinical isolates with three iron uptake-related genes, there were three groups, including salmochelin-yersiniabactin-ferric-iron-positive isolates (n=5), salmochelin-aerobactin-ferric-iron-positive isolates (n=3) and aerobactin-yersiniabactin-ferric iron-positive isolate (n=1). The environmental isolates had only one group including salmochelin- yersiniabactin-ferric-iron-positive isolates (n=3)(Suppl. Figs.1-4).

4. DISCUSSION

Undoubtedly, the role of K. pneumoniae is clear in causing serious infections in people with immunodeficiency and diseases such as those with diabetes mellitus and alcoholics. In recent years, there have been reports of the occurrence of community-acquired liver abscesses in people with a healthy immune system by pathogenic subspecies of K. pneumoniae in Taiwan and some other Asian countries [18Rammaert B, Goyet S, Beauté J, Hem S, Te V, Try PL, et al. Klebsiella pneumoniae related community-acquired acute lower respiratory infections in Cambodia: Clinical characteristics and treatment. 2012; 12(1): 3.]. This syndrome is associated with dissemination into the eye, meninges, brain and other organs. There is a theory that the presence of iron uptake-related genes are effective in increasing the pathogenicity of the less virulent K. pneumoniae subspecies and the presence of these genes may be the reason for the increased pathogenicity of K. pneumoniae [18Rammaert B, Goyet S, Beauté J, Hem S, Te V, Try PL, et al. Klebsiella pneumoniae related community-acquired acute lower respiratory infections in Cambodia: Clinical characteristics and treatment. 2012; 12(1): 3., 19Martin RM, Cao J, Wu W, et al. Identification of pathogenicity-associated loci in Klebsiella pneumoniae from hospitalized patients. mSystems 2018; 3(3): e00015-8.
[http://dx.doi.org/10.1128/mSystems.00015-18] [PMID: 29963640]
]. Although K. pneumoniae is epidemiologically one of the most important species in the Enterobacteriaceae family, unfortunately, little in vivo studies have been conducted on the importance of iron uptake systems in bacterial growth, virulence and the duration of K. pneumoniae infection as compared to other bacterial pathogens [20Tsai F-C, Huang Y-T, Chang L-Y. Pyogenic liver abscess as endemic disease 2008; 14(10): 1592.]. Considering the importance of the iron uptake system in the pathogenesis of K. pneumoniae, this study compared the frequency of genes encoding proteins involved in iron uptake and their prevalence among environmental and clinical strains of K. pneumoniae, which we will discuss below in the results of the studies.

This study examined 300 samples [150 clinical and 150 environmental samples] of K. pneumoniae for the presence of iron uptake-related genes. The clinical samples were urine specimens and more than 90% of environmental samples were isolated from urban sewage.



Table 1
Details of recruited Primers.


Table 2
Frequency of iron uptake genes among the clinical and environmental isolates of K. pneumoniae.


In this study, the frequency of kfuA, iucD, iroN, and yHPI genes were 33.3%, 16.7%, 24.7% and 15.3% in the clinical isolates, as well as 20.7%, 6%, 49.3% and 0.7% in the environmental samples, respectively. The highest frequency in the clinical isolates was related to kfu gene (n=50) followed by iroN (n=37), iucD (25n =) and yHPI (n=23) genes, respectively, and the highest frequency in the environmental isolates was related to the iroN gene (N=74), followed by kfu (n=31), iucD (n=9) and yHPI (nn=1) genes, respectively, but none of the clinical and environmental isolates of K. pneumoniae had hmuR gene.

Frequency distribution of the desired genes involved in the iron uptake system in the clinical isolates of K. pneumoniae cannot be important in terms of gender due to the disparity between the number of isolates among men (38%) and women (62%).

Considering that the presence of kfuA gene in the clinical isolates was more than that of in the environmental isolates, based on the statistical analysis and considering P values <0.05, this difference was statistically significant (P=0.016). However, despite the high prevalence of the iroN gene in the environmental isolates compared to the clinical isolates, this difference was not statistically significant (P=0.077). In addition, due to the higher prevalence of iucD and yHPI genes among the clinical isolates, there was no statistically significant difference between the presence of iucD (p=0.173) and yHPI (P=0.847) genes in the clinical and the environmental isolates.

Huang et al. (2012) in Taiwan introduced the iron uptake system as one of the most important virulence factors in K. pneumoniae. In this study, 34 clinical isolates of K. pneumoniae from liver abscesses had enterobactin (100%), aerobactin (50%), ferric iron (30%), heme (100%) and yersiniabactin (8%) genes [21Huang S-H, Wang C-K, Peng H-L, et al. Role of the small RNA RyhB in the Fur regulon in mediating the capsular polysaccharide biosynthesis and iron acquisition systems in Klebsiella pneumoniae. 2012; 12(1): 148.
[http://dx.doi.org/10.1186/1471-2180-12-148]
].

Aher et al. (2012) examined the frequency of kfu gene among eight isolates of K. pneumoniae isolated from the nose swab and tissue samples, which was reported to be 25% [22Aher T, Roy A, Kumar PJIJoVM. Molecular detection of virulence genes associated with pathogenicity of Klebsiella spp. Isolated from the respiratory tract of apparently healthy as well as sick goats 2012; 67(4): 249-52.]. The Kfu gene may play a major role in bacterial pathogenicity. This operon enables the bacterium to iron uptake even at concentrations of the host body. In our study, the kfu gene had the highest frequency (33.3%) among the clinical specimens and the second place among the environmental samples with a frequency of 20.7%. In a study of Fung in 2012, all 10 strains of K. pneumoniae isolated from the liver abscesses had Diuc [aerobactin], hmuR [heme], and iroN [salmochelin] genes [23Fung C-P, Lin Y-T, Lin J-C, et al. Klebsiella pneumoniae in gastrointestinal tract and pyogenic liver abscess. 2012; 18(8): 1322.]. The K. pneumoniae strains encode the enterobactin, aerobactin, yersiniabactin and salmochelin genes variably. Invasive strains, unlike classical strains, use increasingly salmochelin, aerobactin, ferric iron and yersiniabactin systems. It has been found that these genes are effective in maintaining the infection in the host and also developing a more pathogenic phenotype in K. pneumoniae.

According to the studies, the strains of aerobactin-producing K. pneumoniae had a higher virulence compared to non-producing strains. In addition, these strains are capable of developing acute community-acquired infections [18Rammaert B, Goyet S, Beauté J, Hem S, Te V, Try PL, et al. Klebsiella pneumoniae related community-acquired acute lower respiratory infections in Cambodia: Clinical characteristics and treatment. 2012; 12(1): 3.].

In our study, the frequency of aerobactin and yersiniabactin genes in the clinical samples of K. pneumoniae was nearly 7-18%, as most studies in the world. In some studies, such as a study by Chang et al. on 34 clinical isolates of K. pneumoniae, the frequency of these genes was reported to be 50%. However, the frequency of this gene was lower in the environmental samples, probably confirming the role of these genes in the pathogenicity of K. pneumoniae.

The notable difference in the frequency of iron uptake-related genes between this study and others in the world is the isolation site of samples. In this study, as mentioned, all clinical samples were isolated from urine, while similar studies were mostly performed on the samples isolated from liver and blood abscesses. The nosocomial infections with K. pneumoniae are often involved in urinary and respiratory systems. Since these two organs of the body are in relation to various host defense mechanisms, the virulence factors in the UTI pathogens seem to be different from the strains found in the respiratory tract isolated from the patients with K. pneumoniae.

In this study, it was found that some isolates had more than one iron uptake-related gene. Based on the results of identifying the studied genes, 18.6% [28 isolates] of the clinical isolates and 9.33% of the environmental isolates had two iron uptake-related genes and 6% of the clinical isolates and 2% of the environmental isolates had three iron uptake-related genes. Moreover, 35.33% of the clinical samples and 46.66% of the clinical samples had only one iron uptake-related gene. In this study, the clinical isolates with two iron uptake-related genes were classified into six groups, including aerobactin-yersiniabactin-positive isolates (n=2), salmochelin-aerobactin-positive isolate (n=1), salmochelin-ferric iron-positive isolates (n=10), ferric iron – Yersiniabactin-positive isolates (n=2), aerobactin - ferric iron-positive isolates (n=9) and yersiniabactin – salmochelin-positive isolates (n=4). The environmental isolates were classified into three groups, including salmochelin - ferric iron isolates (n=11), salmochelin - aerobactin isolates (n=2) and salmochelin - yersiniabactin isolate (n=1). In the clinical isolates with three iron uptake-related genes, there were three groups, including salmochelin-yersiniabactin-ferric-iron-positive isolates (n=5), salmochelin-aerobactin-ferric-iron-positive isolates (n=3) and aerobactin-yersiniabactin-ferric iron-positive isolate (n=1). The environmental isolates had only one group including salmochelin-yersiniabactin-ferric-iron-positive isolates (n=3). Although 41.01% of the environmental isolates and 40.07% of the clinical isolates used none of the iron uptake genes examined in this research, the role of these iron uptake-related genes in the pathogenicity of this bacterium could not be ruled out because of failing to evaluate all genes involved in iron uptake in K. pneumoniae in this study, and that this group of K. pneumoniae isolates might have used other iron uptake-related genes.

In a study conducted by Bachman et al. (2011) in the United States on the siderophores expressed by 129 clinical isolates of K. pneumoniae, three groups of the Klebsiella strains were identified including the isolates positive for enterobactin (81%), enterobactin-yersiniabactin (17%), enterobactin-salmochelin [glycosylated enterobactin] with or without yersiniabactin (2%). In this study, the highest prevalence of isolates positive for enterobactin and yersiniabactin was found among the respiratory and β-lactam-resistant isolates and the lowest prevalence in urinary tract isolates, indicating the unnecessary expression of these siderophores in the urinary tract [24Bachman MA, Oyler JE, Burns SH, et al. Klebsiella pneumoniae yersiniabactin promotes respiratory tract infection through evasion of lipocalin 2. 2011; 79(8): 3309-16.].

CONCLUSION

The results of this study can indicate the importance of the ferric iron system in the iron uptake from the host body and the salmochelin system in the iron uptake from the environment. In this study, it was found that the frequency of genes encoding proteins involved in the iron uptake varies between clinical and environmental isolates of K. pneumoniae. The host body conditions and iron availability seem to be effective in the level of using these systems. The results of this study, due to the difference in iron uptake-related genes between clinical and environmental isolates of K. pneumoniae, indicated the significance of iron uptake systems in the virulence of the bacteria. It should also be noted that due to the difference between the isolation sites of the samples in this and other studies, it can be concluded that the hypervirulent and tissue-invasive strains of K. pneumoniae employ further iron uptake systems.

ETHICS APPROVAL AND CONSENT TO PARTICIPATE

The study was approved by The Ilam University of Medical Sciences, Iran.

HUMAN AND ANIMAL RIGHTS

No animals were used in the study. All human procedures were followed in accordance with the ethical standards of the committee responsible for human experimentation (institutional and national), and with the Helsinki Declaration of 1975, as revised in 2008 (http://www.wma.net/en/ 20activities/ 10ethics/10helsinki/).

CONSENT FOR PUBLICATION

Informed consent was obtained from each participants.

AVAILABILITY OF DATA AND MATERIALS

The data that support the findings of this study are available from the corresponding author, [NS], upon reasonable request.

FUNDING

None.

CONFLICT OF INTEREST

The authors declare no conflict of interest, financial or otherwise.

ACKNOWLEDGEMENTS

Declared none.

SUPPLEMENTARY MATERIAL

Supplementary material is available on the publishers web site along with the published article.

Download File


REFERENCES

[1] Gheysarzadeh A, Pakzad I, Valadbeigi H, Maleki A, Sadeghifard N. Antimicrobial resistance and genetic analysis of multi-drug resistant Klebsiella pneumoniae isolates by pulsed-field gel electrophoresis. Gene Rep 2020; 100638.
[2] Martin RM, Bachman MA. Colonization, infection, and the accessory genome of Klebsiella pneumoniae. Front Cell Infect Microbiol 2018; 8: 4.
[http://dx.doi.org/10.3389/fcimb.2018.00004] [PMID: 29404282]
[3] Navon-Venezia S, Kondratyeva K, Carattoli A. Klebsiella pneumoniae: A major worldwide source and shuttle for antibiotic resistance. FEMS Microbiol Rev 2017; 41(3): 252-75.
[http://dx.doi.org/10.1093/femsre/fux013] [PMID: 28521338]
[4] Chang W-N, Lu C-H, Huang C-R, Chuang Y-C, Tsai N-W, Chang C-C, et al. Clinical characteristics of post-neurosurgical Klebsiella pneumoniae meningitis in adults and a clinical comparison to the spontaneous form in a Taiwanese population. 2010; 17(3): 334-8.
[http://dx.doi.org/10.1016/j.jocn.2009.06.019]
[5] Chakma S, Majumdar T, Singh NB. Study of opportunistic pathogens in lower respiratory tract infections among subjects with acquired immune deficiency syndrome [aids] in a tertiary care centre of Tripura. Chart 2017; 12: 14.
[6] Lee IK, Liu J-W, Yang KD. Fatal dengue hemorrhagic fever in adults: Emphasizing the evolutionary pre-fatal clinical and laboratory manifestations. PLoS Negl Trop Dis 2012; 6(2): e1532.
[http://dx.doi.org/10.1371/journal.pntd.0001532] [PMID: 22363829]
[7] Clegg S, Murphy CN. Epidemiology and virulence of Klebsiella pneumoniae In: Urinary Tract Infections: Molecular Pathogenesis and Clinical Management. 2017; 435-57.
[http://dx.doi.org/10.1128/9781555817404.ch18]
[8] Lai Y-C, Yang S-L, Peng H-L, Chang H-YJI. Identification of genes present specifically in a virulent strain of Klebsiella pneumoniae. 2000; 68(12): 7149-51.
[9] Koczura R, Kaznowski A. Occurrence of the Yersinia high-pathogenicity island and iron uptake systems in clinical isolates of Klebsiella pneumoniae. Microb Pathog 2003; 35(5): 197-202.
[http://dx.doi.org/10.1016/S0882-4010(03)00125-6] [PMID: 14521878]
[10] Winkelmann G. Specificity of iron transport in bacteria and fungi Handbook of Microbial Iron Chelates [1991] 2017; 65-106.
[11] Vila A, Cassata A, Pagella H, Amadio C, Yeh K-M, Chang F-Y, et al. Appearance of Klebsiella pneumoniae liver abscess syndrome in Argentina: case report and review of molecular mechanisms of pathogenesis. 2011; 5: 107.
[http://dx.doi.org/10.2174/1874285801105010107]
[12] Pilo F, Angelucci E. A storm in the niche: Iron, oxidative stress and haemopoiesis. Blood Rev 2018; 32(1): 29-35.
[http://dx.doi.org/10.1016/j.blre.2017.08.005] [PMID: 28847531]
[13] Moranta Mesquida D, Regueiro V, March C, Llobet E, Margareto J, Larrarte E, et al. Klebsiella pneumoniae capsule polysaccharide impedes the expression of beta-defensins by airway epithelial cells. 2018.
[14] Ellermann M, Arthur JC. Siderophore-mediated iron acquisition and modulation of host-bacterial interactions. Free Radic Biol Med 2017; 105: 68-78.
[http://dx.doi.org/10.1016/j.freeradbiomed.2016.10.489] [PMID: 27780750]
[15] Tu Y-C, Lu M-C, Chiang M-K, Huang S-P, Peng H-L, Chang H-Y, et al. Genetic requirements for Klebsiella pneumoniae-induced liver abscess in an oral infection model 2009.
[http://dx.doi.org/10.1128/IAI.01523-08]
[16] Dogan O, Vatansever C, Atac N, Albayrak O, Karahuseyinoglu S, Sahin OE, et al. The role of iron uptake systems in the pathogenesis of colistin-resistant hypervirulent K. pneumoniae infections. bioRxiv 2019; 677492.
[17] Smith AT, Sestok AE. Expression and purification of functionally active ferrous iron transporter FeoB from Klebsiella pneumoniae. Protein Expr Purif 2018; 142: 1-7.
[http://dx.doi.org/10.1016/j.pep.2017.09.007] [PMID: 28941825]
[18] Rammaert B, Goyet S, Beauté J, Hem S, Te V, Try PL, et al. Klebsiella pneumoniae related community-acquired acute lower respiratory infections in Cambodia: Clinical characteristics and treatment. 2012; 12(1): 3.
[19] Martin RM, Cao J, Wu W, et al. Identification of pathogenicity-associated loci in Klebsiella pneumoniae from hospitalized patients. mSystems 2018; 3(3): e00015-8.
[http://dx.doi.org/10.1128/mSystems.00015-18] [PMID: 29963640]
[20] Tsai F-C, Huang Y-T, Chang L-Y. Pyogenic liver abscess as endemic disease 2008; 14(10): 1592.
[21] Huang S-H, Wang C-K, Peng H-L, et al. Role of the small RNA RyhB in the Fur regulon in mediating the capsular polysaccharide biosynthesis and iron acquisition systems in Klebsiella pneumoniae. 2012; 12(1): 148.
[http://dx.doi.org/10.1186/1471-2180-12-148]
[22] Aher T, Roy A, Kumar PJIJoVM. Molecular detection of virulence genes associated with pathogenicity of Klebsiella spp. Isolated from the respiratory tract of apparently healthy as well as sick goats 2012; 67(4): 249-52.
[23] Fung C-P, Lin Y-T, Lin J-C, et al. Klebsiella pneumoniae in gastrointestinal tract and pyogenic liver abscess. 2012; 18(8): 1322.
[24] Bachman MA, Oyler JE, Burns SH, et al. Klebsiella pneumoniae yersiniabactin promotes respiratory tract infection through evasion of lipocalin 2. 2011; 79(8): 3309-16.
Track Your Manuscript:


Endorsements



"Open access will revolutionize 21st century knowledge work and accelerate the diffusion of ideas and evidence that support just in time learning and the evolution of thinking in a number of disciplines."


Daniel Pesut
(Indiana University School of Nursing, USA)

"It is important that students and researchers from all over the world can have easy access to relevant, high-standard and timely scientific information. This is exactly what Open Access Journals provide and this is the reason why I support this endeavor."


Jacques Descotes
(Centre Antipoison-Centre de Pharmacovigilance, France)

"Publishing research articles is the key for future scientific progress. Open Access publishing is therefore of utmost importance for wider dissemination of information, and will help serving the best interest of the scientific community."


Patrice Talaga
(UCB S.A., Belgium)

"Open access journals are a novel concept in the medical literature. They offer accessible information to a wide variety of individuals, including physicians, medical students, clinical investigators, and the general public. They are an outstanding source of medical and scientific information."


Jeffrey M. Weinberg
(St. Luke's-Roosevelt Hospital Center, USA)

"Open access journals are extremely useful for graduate students, investigators and all other interested persons to read important scientific articles and subscribe scientific journals. Indeed, the research articles span a wide range of area and of high quality. This is specially a must for researchers belonging to institutions with limited library facility and funding to subscribe scientific journals."


Debomoy K. Lahiri
(Indiana University School of Medicine, USA)

"Open access journals represent a major break-through in publishing. They provide easy access to the latest research on a wide variety of issues. Relevant and timely articles are made available in a fraction of the time taken by more conventional publishers. Articles are of uniformly high quality and written by the world's leading authorities."


Robert Looney
(Naval Postgraduate School, USA)

"Open access journals have transformed the way scientific data is published and disseminated: particularly, whilst ensuring a high quality standard and transparency in the editorial process, they have increased the access to the scientific literature by those researchers that have limited library support or that are working on small budgets."


Richard Reithinger
(Westat, USA)

"Not only do open access journals greatly improve the access to high quality information for scientists in the developing world, it also provides extra exposure for our papers."


J. Ferwerda
(University of Oxford, UK)

"Open Access 'Chemistry' Journals allow the dissemination of knowledge at your finger tips without paying for the scientific content."


Sean L. Kitson
(Almac Sciences, Northern Ireland)

"In principle, all scientific journals should have open access, as should be science itself. Open access journals are very helpful for students, researchers and the general public including people from institutions which do not have library or cannot afford to subscribe scientific journals. The articles are high standard and cover a wide area."


Hubert Wolterbeek
(Delft University of Technology, The Netherlands)

"The widest possible diffusion of information is critical for the advancement of science. In this perspective, open access journals are instrumental in fostering researches and achievements."


Alessandro Laviano
(Sapienza - University of Rome, Italy)

"Open access journals are very useful for all scientists as they can have quick information in the different fields of science."


Philippe Hernigou
(Paris University, France)

"There are many scientists who can not afford the rather expensive subscriptions to scientific journals. Open access journals offer a good alternative for free access to good quality scientific information."


Fidel Toldrá
(Instituto de Agroquimica y Tecnologia de Alimentos, Spain)

"Open access journals have become a fundamental tool for students, researchers, patients and the general public. Many people from institutions which do not have library or cannot afford to subscribe scientific journals benefit of them on a daily basis. The articles are among the best and cover most scientific areas."


M. Bendandi
(University Clinic of Navarre, Spain)

"These journals provide researchers with a platform for rapid, open access scientific communication. The articles are of high quality and broad scope."


Peter Chiba
(University of Vienna, Austria)

"Open access journals are probably one of the most important contributions to promote and diffuse science worldwide."


Jaime Sampaio
(University of Trás-os-Montes e Alto Douro, Portugal)

"Open access journals make up a new and rather revolutionary way to scientific publication. This option opens several quite interesting possibilities to disseminate openly and freely new knowledge and even to facilitate interpersonal communication among scientists."


Eduardo A. Castro
(INIFTA, Argentina)

"Open access journals are freely available online throughout the world, for you to read, download, copy, distribute, and use. The articles published in the open access journals are high quality and cover a wide range of fields."


Kenji Hashimoto
(Chiba University, Japan)

"Open Access journals offer an innovative and efficient way of publication for academics and professionals in a wide range of disciplines. The papers published are of high quality after rigorous peer review and they are Indexed in: major international databases. I read Open Access journals to keep abreast of the recent development in my field of study."


Daniel Shek
(Chinese University of Hong Kong, Hong Kong)

"It is a modern trend for publishers to establish open access journals. Researchers, faculty members, and students will be greatly benefited by the new journals of Bentham Science Publishers Ltd. in this category."


Jih Ru Hwu
(National Central University, Taiwan)


Browse Contents




Webmaster Contact: info@benthamopen.net
Copyright © 2020 Bentham Open