Genetic Diversity, Antimicrobial Resistance Pattern, and Biofilm Formation in Klebsiella pneumoniae Isolated from Patients with Coronavirus Disease 2019 (COVID-19) and Ventilator-Associated Pneumonia

Introduction. Patients with acute respiratory distress syndrome caused by coronavirus disease 2019 (COVID-19) are at risk for superadded infections, especially infections caused by multidrug resistant (MDR) pathogens. Before the COVID-19 pandemic, the prevalence of MDR infections, including infections caused by MDR Klebsiella pneumoniae (K. pneumoniae), was very high in Iran. This study is aimed at assessing the genetic diversity, antimicrobial resistance pattern, and biofilm formation in K. pneumoniae isolates obtained from patients with COVID-19 and ventilator-associated pneumonia (VAP) hospitalized in an intensive care unit (ICU) in Iran. Methods. In this cross-sectional study, seventy K. pneumoniae isolates were obtained from seventy patients with COVID-19 hospitalized in the ICU of Shahid Beheshti hospital, Kashan, Iran, from May to September, 2020. K. pneumoniae was detected through the ureD gene. Antimicrobial susceptibility testing was done using the Kirby-Bauer disc diffusion method, and biofilm was detected using the microtiter plate assay method. Genetic diversity was also analyzed through polymerase chain reaction based on enterobacterial repetitive intergenic consensus (ERIC-PCR). The BioNumerics software (v. 8.0, Applied Maths, Belgium) was used for analyzing the data and drawing dendrogram and minimum spanning tree. Findings. K. pneumoniae isolates had varying levels of resistance to antibiotics meropenem (80.4%), cefepime-aztreonam-piperacillin/tazobactam (70%), tobramycin (61.4%), ciprofloxacin (57.7%), gentamicin (55.7%), and imipenem (50%). Around 77.14% of isolates were MDR, and 42.8% of them formed biofilm. Genetic diversity analysis revealed 28 genotypes (E1–E28) and 74.28% of isolates were grouped into ten clusters (i.e., clusters A–J). Clusters were further categorized into three major clusters, i.e., clusters E, H, and J. Antimicrobial resistance to meropenem, tobramycin, gentamicin, and ciprofloxacin in cluster J was significantly higher than cluster H, denoting significant relationship between ERIC clusters and antimicrobial resistance. However, there was no significant difference among major clusters E, H, and J respecting biofilm formation. Conclusion. K. pneumoniae isolates obtained from patients with COVID-19 have high antimicrobial resistance, and 44.2% of them have genetic similarity and can be clustered in three major clusters. There is a significant difference among clusters respecting antimicrobial resistance.

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Colistin Susceptibility in Carbapenem Resistant Klebsiella Pneumoniae and their Ability of Biofilm Formation

Iraqi Journal of Science ◽

10.24996/ijs.2020.61.3.7 ◽

2020 ◽

pp. 517-527

Author(s):

Sarab Murad Kadum

Keyword(s):

Klebsiella Pneumoniae ◽

Resistance Gene ◽

Biofilm Formation ◽

Rpob Gene ◽

Resistance Rate ◽

Diffusion Method ◽

Clinical Samples ◽

Resistance Pattern ◽

Specific Primer ◽

Carbapenem Resistant

A total of 157 clinical samples were collected from different clinical specimens (urine, sputum, blood, swabs, and cannula) from several hospitals in Iraq. Among the samples, 51 isolates (32.48%) of Klebsiella pneumoniae were identified according to morphologicaland cultural characteristics as well as the Enterosystem 18R test. Higher numbers of K. pneumoniae isolates were observed in urine samples (26, 52%) than the other samples, and in females (70.6%) than males (29.4%) (female: male ratio of about 2.4:1). Antibiotic susceptibility of K. pneumoniae against 12 commonly used antibiotics was determined through the disc-diffusion method. The results revealed a higher resistance rate in 51 isolates (100%) against Cephalexin, followed by Ceftazidime (50, 98%), while the lowest resistance rate (24, 47%) was against each of Imipenem and Meropenem. Also, the investigation of the minimum inhibitory concentration (MIC) of Colistin using E-test (strips) demonstrated that 33 isolates were resistance, as compared to 31 using the disk diffusion assay. DNA was extracted from K. pneumoniae isolates and molecularly tested using polymerase chain technique (PCR) with a specific primer and 108 bp product to detect the rpoB gene that represents this bacteria . Also, all of the 51 isolates of K. pneumoniae identified by the rpoB gene were detected for the expression of the Colistin drug resistance gene mgr-B , which was amplified (347 bp) using a specific primer. Colistin resistance gene mgr-B was amplified and sequenced from the twenty isolates. Only 6 isolates appeared with a single nucleotide substitution; G instead A, A instead G, C instead G and G instead C. Also, this study tested biofilm formation from K. pneumoniae isolates , using the microtiter plate method, in association with Colistin and Carbapenem resistant. The Colistin and Carbapenem resistance pattern was compared to the ability of biofilm-formation as weak formation versus strong and also, Multi-drug resistant isolates were more common among weak versus strong biofilm formers.

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Investigation of Antibiotic Resistance and Biofilm Formation in Clinical Isolates of Klebsiella pneumoniae

International Journal of Microbiology ◽

10.1155/2021/5573388 ◽

2021 ◽

Vol 2021 ◽

pp. 1-6

Author(s):

Kiana Karimi ◽

Omid Zarei ◽

Parinaz Sedighi ◽

Mohammad Taheri ◽

Amin Doosti-Irani ◽

...

Keyword(s):

Antibiotic Resistance ◽

Klebsiella Pneumoniae ◽

Biofilm Formation ◽

Diffusion Method ◽

Clinical Samples ◽

Resistance Pattern ◽

Chi Square ◽

Disk Diffusion Method ◽

High Level ◽

Tract Infections

Aim. Klebsiella pneumoniae (K. pneumoniae) is an encapsulated Gram-negative bacterium that can lead to 14–20% of nosocomial infections. The ability of biofilm formation in this bacterium decreases the host immune response and antibiotic efficacy. This may impose a huge impact on patients and healthcare settings. This study aimed to evaluate the antibiotic resistance pattern and biofilm formation in K. pneumoniae strains isolated from two major Hamadan hospitals, west of Iran. Methods. A total of 83 K. pneumoniae strains were isolated from clinical samples of patients in different wards of Hamadan hospitals from September 2018 to March 2019. Determination of antimicrobial susceptibility was performed using the disk diffusion method. Biofilm formation was evaluated by the crystal violet method. Data were analyzed by the SPSS software and chi-square test. Results. The results showed that clinical samples included 18 urinary tract samples (22%), 6 wound samples (7%), 6 blood samples (7%), 17 tracheal tube aspiration samples (20%), 32 throat cultures (38%), 2 sputum samples (2.5%), and 2 abscess drain cultures (2.5%). High-level resistance to cefotaxime was detected in 92%, and all of isolates were susceptible to colistin. Biofilm formation was seen in 62 (75%) isolates. Strong biofilm formation was observed in 17 (20%) strains. A significant correlation was seen between biofilm formation and antibiotic resistance ( P value <0.05). Conclusion. Our findings emphasize the need for proper diagnosis, control, and treatment of infections caused by K. pneumoniae especially in respiratory tract infections due to the strong biofilm formation and high antibiotic resistance in these strains.

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Comparison of biofilm formation and efflux pumps in ESBL and carbapenemase producing Klebsiella pneumoniae

The Journal of Infection in Developing Countries ◽

10.3855/jidc.9677 ◽

2018 ◽

Vol 12 (03) ◽

pp. 156-163 ◽

Cited By ~ 1

Author(s):

Burak Yazgan ◽

Ibrahim Türkel ◽

Rıdvan Güçkan ◽

Kılınç Kılınç ◽

Tuba Yıldırım

Keyword(s):

Klebsiella Pneumoniae ◽

Biofilm Formation ◽

Cell Communication ◽

Opportunistic Pathogen ◽

Efflux Pumps ◽

Microtiter Plate ◽

Virulence Determinants ◽

Clinical Environment ◽

Microtiter Plate Assay ◽

Significant Difference

Introduction: Klebsiella pneumoniae is an opportunistic pathogen that causes a range of diseases. The appearance of extended-spectrum β-lactamase -and carbapenemase-producing strains, in addition to the biofilm-forming phenotype, is a major problem in the clinical environment. Methodology: A total of 33 clinical K. pneumoniae isolates were used in this study. Antimicrobial susceptibilities were assessed by a disc diffusion assay. Biofilm formation was determined by a microtiter plate assay, staining with 1% crystal violet and measuring absorbance after destaining. Moreover, expression of acrA, kdeA, ketM, kpnEF, and kexD efflux associated genes was measured by qRT-PCR. Results: Isolates displayed high resistance to β-lactams such as cefazolin, cefuroxime, ceftriaxone, cefepime, piperacillin-tazobactam, imipenem, and meropenem and decreased resistance to gentamicin, amikacin, ciprofloxacin, and levofloxacin. ESBL-producing isolates formed more biofilm than carbapenemase-producing isolates. The mRNA expression levels in KPC isolates for acrA (2-fold), kdeA (2.7-fold), ketM (2.2-fold), and kpnEF (3.4-fold) were significantly increased compared to ESBL-producing isolates. There was no significant difference in kexD expression level. Conclusions: Under the conditions used here ESBL-producing isolates formed more biofilm than KPC postive isolates; this was associated with virulence determinants which were also transferred by plasmids together with ESBLs enzymes. Moreover, the upregulation of acrA, kdeA, ketM, and kpnEF efflux pumps was seen in carbapenemase-producing isolates demonstrating that high expression of efflux pumps alone could not confer resistance but may act as a physiological determinant such as bacterial pathogenicity and virulence, and cell-to-cell communication for bacteria.

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Biofilm production and its effects on virulence of MRSA: a study in tertiary care hospital, Delhi

International Journal of Community Medicine and Public Health ◽

10.18203/2394-6040.ijcmph20203916 ◽

2020 ◽

Vol 7 (9) ◽

pp. 3518

Author(s):

Amir Khan ◽

Rachna Tewari ◽

Neetusree . ◽

Mridu Dudeja

Keyword(s):

Antimicrobial Resistance ◽

Biofilm Formation ◽

Automated System ◽

Assay Method ◽

Common Source ◽

Care Hospital ◽

Microtiter Plate Assay ◽

Biofilm Production ◽

Antibiotic Susceptibility Test ◽

Mrsa Strains

Background: The aim of this study was to study the prevalence of biofilm formation in MRSA and its effect on virulence and the antimicrobial resistance pattern on MRSA strains from different clinical samples.Methods: A total of 221 isolates of S. aureus isolates were selected from various clinical specimens. Prevalence was estimated according to age, sex, and location. The antibiotic susceptibility test was conducted according to the guidelines of CLSI by the VITEK 2 automated system. 113 strains were identified as MRSA by cefoxitin disc methods which were then subjected to Microtiter plate assay method to confirm phenotypic biofilm formation.Results: 51.13% isolates were resistant to methicillin, and 48.86% isolates were methicillin sensitive. The most common source of MRSA isolation was blood. MRSA isolates were mostly isolated from male. 33.63% MRSA and 19.44% MSSA isolates were strong biofilm producers while 12.38% MRSA and 14.81% were low biofilm producers. The resistance for commonly used antibiotics like benzyle penicillin, ciprofloxacin, cotrimoxazole, and erythromycin was more in MRSA strains and MIC was higher in biofilm producers.Conclusion: Statistical difference was observed between MSSA and MRSA regarding biofilm formation and antimicrobial resistance. A Biofilm producer shows resistance to many antibiotics and also make host immunity in effective. In hospitals Biofilm production should be checked regularly before giving treatment. And research should be done to find out other effective drugs to eradicate biofilms.

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Correlation Between Antimicrobial Resistance and Biofilm Formation Capability Among Klebsiella Pneumoniae Strains Isolated From Hospitalized Patients in Iran

10.21203/rs.3.rs-112921/v1 ◽

2020 ◽

Author(s):

Shadi Shadkam ◽

Hamid Reza Goli ◽

Bahman Mirzaei ◽

Mehrdad Gholami ◽

Mohammad Ahanjan

Keyword(s):

Antibiotic Resistance ◽

Antimicrobial Resistance ◽

Klebsiella Pneumoniae ◽

Biofilm Formation ◽

Treatment Options ◽

Hospital Setting ◽

Hospitalized Patients ◽

Diffusion Method ◽

Disk Diffusion Method ◽

Antibiotic Susceptibility Test

Abstract BackgroundKlebsiella pneumoniae (K. pneumoniae) is a common cause of nosocomial infections. Antibiotic resistance and ability to form biofilm, as two key virulence factors of K. pneumoniae, involved in persistent of the infections. The purpose of this study is to investigate the correlation between antimicrobial resistance and biofilm formation capability among K. pneumoniae strains isolated from hospitalized patients in Iran.MethodsOver a 10-month period, a total of 100 non-duplicate K. pneumoniae strains were collected. Antibiotic susceptibility test was determined by Kirby-Bauer disk diffusion method according to CLSI. Biofilm formation was assessed by tissue culture plate method. Finally, polymerase chain reaction was conducted to detect four families of carbapenemase: blaIMP, blaVIM, blaNDM, blaOXA-48, biofilm formation associated genes; treC, wza, luxS and K. pneumoniae confirming gene; rpoB.ResultsMost of the isolates were resistant to co-trimoxazole (52%), cefotaxime (51%), cefepime (43%), and ceftriaxone (43%). Among all the 100 isolates, 67 were multidrug-resistant (MDR), and 11 were extensively drug-resistant (XDR). The prevalence of the blaVIM, blaIMP, blaNDM, and blaOXA-48 genes were 7%, 11%, 5%, and 28%, respectively. Among these isolates, 25% formed fully established biofilms, 19% were categorized as moderately biofilm-producing, 31% formed weak biofilms, and 25% were non-biofilm-producers. Molecular distribution of biofilm formation genes revealed that 98%, 96%, and 34% of the isolates carried luxS, treC, and wza genes, respectively. ConclusionThe rise of antibiotic resistance among biofilm-producer strains, demonstrating a serious alarm about limited treatment options in hospital setting. Also, fundamental actions and introduction of novel strategies for controlling of K. pneumoniae biofilm-related infections is essential.

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Correlation between antimicrobial resistance and biofilm formation capability among Klebsiella pneumoniae strains isolated from hospitalized patients in Iran

Annals of Clinical Microbiology and Antimicrobials ◽

10.1186/s12941-021-00418-x ◽

2021 ◽

Vol 20 (1) ◽

Author(s):

Shadi Shadkam ◽

Hamid Reza Goli ◽

Bahman Mirzaei ◽

Mehrdad Gholami ◽

Mohammad Ahanjan

Keyword(s):

Tissue Culture ◽

Antibiotic Resistance ◽

Antimicrobial Resistance ◽

Klebsiella Pneumoniae ◽

Biofilm Formation ◽

Hospitalized Patients ◽

Diffusion Method ◽

Disk Diffusion Method ◽

Culture Plate ◽

Tissue Culture Plate

Abstract Background Klebsiella pneumoniae is a common cause of nosocomial infections. Antibiotic resistance and ability to form biofilm, as two key virulence factors of K. pneumoniae, are involved in the persistence of infections. The purpose of this study was to investigate the correlation between antimicrobial resistance and biofilm formation capability among K. pneumoniae strains isolated from hospitalized patients in Iran. Methods Over a 10-month period, a total of 100 non-duplicate K. pneumoniae strains were collected. Antibiotic susceptibility was determined by Kirby–Bauer disk diffusion method according to CLSI. Biofilm production was assessed by tissue culture plate method. Finally, polymerase chain reaction was conducted to detect four families of carbapenemase: blaIMP, blaVIM, blaNDM, blaOXA−48; biofilm formation associated genes: treC, wza, luxS; and K. pneumoniae confirming gene: rpoB. Results Most of the isolates were resistant to trimethoprim-sulfamethoxazole (52 %), cefotaxime (51 %), cefepime (43 %), and ceftriaxone (43 %). Among all the 100 isolates, 67 were multidrug-resistant (MDR), and 11 were extensively drug-resistant (XDR). The prevalence of the blaVIM, blaIMP, blaNDM, and blaOXA−48 genes were 7 , 11 , 5 , and 28 %, respectively. The results of biofilm formation in the tissue culture plate assay indicated that 75 (75 %) strains could produce biofilm and only 25 (25 %) isolates were not able to form biofilm. Among these isolates, 25 % formed fully established biofilms, 19 % were categorized as moderately biofilm-producing, 31 % formed weak biofilms, and 25 % were non-biofilm-producers. The antimicrobial resistance among biofilm former strains was found to be significantly higher than that of non-biofilm former strains (p < 0.05). Molecular distribution of biofilm formation genes revealed that 98 , 96 , and 34 % of the isolates carried luxS, treC, and wza genes, respectively. Conclusions The rise of antibiotic resistance among biofilm-producer strains demonstrates a serious concern about limited treatment options in the hospital settings. All of the data suggest that fundamental actions and introduction of novel strategies for controlling of K. pneumoniae biofilm-related infections is essential.

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MrkD Gene as a Regulator of Biofilm Formation with Correlation to Antibiotic Resistance among Clinical Klebsiella pneumoniae Isolates from Menoufia University Hospitals

10.51429/ejmm29318 ◽

2020 ◽

Vol 29 (3) ◽

pp. 137-144

Author(s):

Asmaa M. Elbrolosy ◽

Naira A. Eissa ◽

Nahed A. Al-Rajhy ◽

Esraa El-Sayed A. El-Mahdy ◽

Rasha G. Mostafa

Keyword(s):

Antibiotic Resistance ◽

Klebsiella Pneumoniae ◽

Biofilm Formation ◽

Diffusion Method ◽

Clinical Samples ◽

Resistance Pattern ◽

University Hospitals ◽

Pcr Assay ◽

Disk Diffusion Method ◽

Microbiological Methods

Background: Klebsiella pneumoniae (K. pneumoniae) is a common pathogen involved in a diverse array of life-threatening infections. Increasing frequent acquisition of antibiotic resistance by K. pneumoniae has given rise to multidrug-resistant pathogen mostly at the hospital level. Objectives: To assess the prevalence and antibiotic resistance pattern of the clinical K. pneumoniae isolates at Menoufia University Hospitals (MUHs) as well as to explore the role of mrkD gene as a regulator of biofilm formation. Methodology: A total of 340 different clinical samples were obtained from 270 patients who were admitted to MUHs and those from Outpatient clinics during the period from April 2018 to September 2019. 84 K. pneumoniae isolates were identified by the standard microbiological methods and vitek-2 system. The antimicrobial resistance pattern was determined by disk diffusion method. The biofilm-forming ability of all K. pneumoniae isolates was demonstrated phenotypically by the modified Congo red agar method (MCRA) and PCR assay verified the presence of mrkD gene as a genetic determinant of biofilm formation. Results: Klebsiella spp. represented 34.7% of the collected isolates and the predominant spp. was K. pneumoniae (91.3%). The highest resistance rates were for ceftriaxone (69%) followed by aztreonam (67.9%), 66.7% for each of piperacillin and ceftazidime, while the least resistance rate was for fosfomycin (8.3%). Biofilm production was detected among 83.3% of the isolates by MCRA method. A highly significant statistical difference was noted between biofilm- and non- biofilm - producing K. pneumoniae isolates regarding resistance to cefepieme and amikacin (P <0.001) and similarly regarding resistance to aztreonam, imipenem, meropenem, ertapenem and tobramycin (P<0.05). Conventional PCR assay showed that, 92% of the isolates harbored mrkD gene with a highly significant association with biofilm formation. Conclusion: The increasing prevalence and remarkable ability to acquire antibiotic resistance among K. pneumoniae isolates together with biofilm formation should alert even more regarding the hazard of this pathogen in hospital settings.

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Occurrence, antimicrobial resistance pattern and molecular characterization of Listeria monocytogenes isolated from bovine’s milk and meat in Mekelle City, Ethiopia

10.1101/2021.11.16.468824 ◽

2021 ◽

Author(s):

Getachew Gugsa Amede ◽

Tesfay Hailu Kidanu ◽

Yisehak Tsegaye Redda ◽

Meselu Ahmed Ali ◽

Nesibu Awol Ababelgu

Keyword(s):

Listeria Monocytogenes ◽

Antimicrobial Resistance ◽

Diffusion Method ◽

Resistance Pattern ◽

Sample Type ◽

Prevalence Rates ◽

Isolation And Identification ◽

Significant Difference ◽

Mekelle City ◽

Meat Samples

Listeria monocytogenes is an opportunistic and emerging foodborne zoonotic pathogen that encompasses a diversity of strains with varied virulence and can cause serious human and animal infections worldwide with low incidence but high hospitalization and case fatality rates. A cross-sectional study was conducted from December 2016 to June 2017 to estimate the molecular epidemiology of L. monocytogenes and its serotypes, and antimicrobial resistance pattern of isolates in Mekelle City. A total of 768 (384 of milk and 384 meat) samples of bovine origin were collected using a purposive random sampling technique. Isolation and identification of L. monocytogenes was done according to standard and recommended bacteriological procedures. Genome-based confirmation of each isolate was performed at species and serovar levels by targeting Iap, Imo0737, ORF2819 and ORF2110 genes using specific primers. In vitro antimicrobial susceptibility testing was performed using agar plate antibiotic disk diffusion method. The overall prevalence of L. monocytogenes was 26 (3.39%). Sample type prevalence rates of L. monocytogenes were 4.17 % and 2.6% in meat and milk samples, respectively. There was a statically significant difference (p<0.05) on the prevalence rates of the organism in meat samples collected from abattoir (1.67%), butcher shops (8.33%), and restaurants (8.33%). Serovars that were identified were belonged to 1/2b and 4b. Large proportions of isolates were highly susceptible to Ampicillin (88.46%) and Vancomycin (84.62%). However, the isolates had shown the highest level of resistance against Nalidixic Acid (96.15%). The highest intermediate was observed to Amoxicillin (57.69%). Moreover, 42.31% of the isolates were developed resistance for more than two drugs. Hence, both its occurrence and development of a multi-drug resistance indicated that, a coordinated effort is imperative to reduce or eliminate the risk posed by this pathogen in food chains and on controlled and careful use of antimicrobials both in veterinary and human treatment regimes.

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Comparison of Prevalence, Antimicrobial Resistance, and Occurrence of Multidrug-Resistant Salmonella in Antimicrobial-Free and Conventional Pig Production

Journal of Food Protection ◽

10.4315/0362-028x-69.4.743 ◽

2006 ◽

Vol 69 (4) ◽

pp. 743-748 ◽

Cited By ~ 39

Author(s):

WONDWOSSEN A. GEBREYES ◽

SIDDHARTHA THAKUR ◽

W. E. MORGAN MORROW

Keyword(s):

Antimicrobial Resistance ◽

Production Systems ◽

Multidrug Resistant ◽

Resistance Pattern ◽

Swine Production ◽

Significant Difference ◽

Conventional Farms ◽

Resistance Patterns ◽

Conventional Systems ◽

On Farm

Conventional swine production evolved to routinely use antimicrobials, and common occurrence of antimicrobial-resistant Salmonella has been reported. There is a paucity of information on the antimicrobial resistance of Salmonella in swine production in the absence of antimicrobial selective pressure. Therefore, we compared the prevalence and antimicrobial resistance of Salmonella isolated from antimicrobial-free and conventional production systems. A total of 889 pigs and 743 carcasses were sampled in the study. Salmonella prevalence was significantly higher among the antimicrobial-free systems (15.2%) than the conventional systems (4.2%) (odds ratio [OR] = 4.23; P < 0.05). Antimicrobial resistance was detected against 10 of the 12 antimicrobials tested. The highest frequency of resistance was found against tetracycline (80%), followed by streptomycin (43.4%) and sulfamethoxazole (36%). Frequency of resistance to most classes of antimicrobials (except tetracycline) was significantly higher among conventional farms than antimicrobial-free farms, with ORs ranging from 2.84 for chloramphenicol to 23.22 for kanamycin at the on-farm level. A total of 28 antimicrobial resistance patterns were detected. A resistance pattern with streptomycin, sulfamethoxazole, and tetracycline (n = 130) was the most common multidrug resistance pattern. There was no significant difference in the proportion of isolates with this pattern between the conventional (19.5%) and the antimicrobial-free systems (18%) (OR = 1.8; P > 0.05). A pentaresistance pattern with ampicillin, chloramphenicol, streptomycin, sulfamethoxazole, and tetracycline was strongly associated with antimicrobial-free groups (OR = 5.4; P = 0.01). While showing the higher likelihood of finding antimicrobial resistance among conventional herds, this study also implies that specific multidrug-resistant strains may occur on antimicrobial-free farms. A longitudinal study with a representative sample size is needed to reach more conclusive results of the associations detected in this study.

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Antibiofilm and antivirulence potential of silver nanoparticles against multidrug-resistant Acinetobacter baumannii

Scientific Reports ◽

10.1038/s41598-021-90208-4 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Helal F. Hetta ◽

Israa M. S. Al-Kadmy ◽

Saba Saadoon Khazaal ◽

Suhad Abbas ◽

Ahmed Suhail ◽

...

Keyword(s):

Silver Nanoparticles ◽

Antibacterial Activity ◽

Acinetobacter Baumannii ◽

Biofilm Formation ◽

Microtiter Plate ◽

Diffusion Method ◽

Resistance Pattern ◽

Infection Model ◽

The Impact

AbstractWe aimed to isolate Acinetobacter baumannii (A. baumannii) from wound infections, determine their resistance and virulence profile, and assess the impact of Silver nanoparticles (AgNPs) on the bacterial growth, virulence and biofilm-related gene expression. AgNPs were synthesized and characterized using TEM, XRD and FTIR spectroscopy. A. baumannii (n = 200) were isolated and identified. Resistance pattern was determined and virulence genes (afa/draBC, cnf1, cnf2, csgA, cvaC, fimH, fyuA, ibeA, iutA, kpsMT II, PAI, papC, PapG II, III, sfa/focDE and traT) were screened using PCR. Biofilm formation was evaluated using Microtiter plate method. Then, the antimicrobial activity of AgNPs was evaluated by the well-diffusion method, growth kinetics and MIC determination. Inhibition of biofilm formation and the ability to disperse biofilms in exposure to AgNPs were evaluated. The effect of AgNPs on the expression of virulence and biofilm-related genes (bap, OmpA, abaI, csuA/B, A1S_2091, A1S_1510, A1S_0690, A1S_0114) were estimated using QRT-PCR. In vitro infection model for analyzing the antibacterial activity of AgNPs was done using a co-culture infection model of A. baumannii with human fibroblast skin cell line HFF-1 or Vero cell lines. A. baumannii had high level of resistance to antibiotics. Most of the isolates harbored the fimH, afa/draBC, cnf1, csgA and cnf2, and the majority of A. baumannii produced strong biofilms. AgNPs inhibited the growth of A. baumannii efficiently with MIC ranging from 4 to 25 µg/ml. A. baumannii showed a reduced growth rate in the presence of AgNPs. The inhibitory activity and the anti-biofilm activity of AgNPs were more pronounced against the weak biofilm producers. Moreover, AgNPs decreased the expression of kpsMII , afa/draBC,bap, OmpA, and csuA/B genes. The in vitro infection model revealed a significant antibacterial activity of AgNPs against extracellular and intracellular A. baumannii. AgNPs highly interrupted bacterial multiplication and biofilm formation. AgNPs downregulated the transcription level of important virulence and biofilm-related genes. Our findings provide an additional step towards understanding the mechanisms by which sliver nanoparticles interfere with the microbial spread and persistence.

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