فهرست مطالب

  • Volume:12 Issue:10, 2020
  • تاریخ انتشار: 1398/10/11
  • تعداد عناوین: 6
|
  • Narjes Mohammadi Bandari, Mohsen Zargar *, Hossein Keyvani, Malihe Talebi, Mohammad Reza Zolfaghari Page 1
    Background

    The prevalent emergence of carbapenem-resistant Enterobacteriaceae, especially Klebsiella pneumoniae carbapenemases (KPC) that causes infection associated with multidrug-resistant, is a major clinical and public health concern. Accurate and fast detection of carbapenemases is essential for effective infection control.

    Objectives

    The aims of this study were the detection of blaKPC and blaGES genes with phenotypic and genotypic methods, evaluation of expression level of these genes in the presence and absence of β-lactam antibiotic, and determination of antibiotic resistance patterns among K. pneumoniae isolated at Firoozgar Hospital.

    Methods

    One hundred and eighty-one K. pneumoniae strains were collected from patients presenting to Firoozgar Hospital of Tehran, Iran from March 2018 to December 2018. The strains were tested using the disk diffusion method, modified Hodge test (MHT), and minimum inhibitory concentration (MIC). The presence of blaKPC and blaGES resistance genes was detected by RT-PCR. The blaKPC and blaGES genes expression level was measured by real-time PCR in the presence and absence of β-lactam antibiotic.

    Results

    The results of this study showed the highest and lowest rates of resistance to cefepime and imipenem were 83.9% and 55.2%, respectively. 100 strains were positive as KPC-producing in MHT. Also, they exhibited resistance to imipenem by E-test. 51% and 49% of these 100 isolates were positive for blaKPC and blaGES genes, respectively. Real-time PCR assay showed the higher expression level of blaKPC (1.04 folds) and blaGES (12.21 folds) increase in resistant strains in the presence of imipenem.

    Conclusions

    Due to the high resistance of K. pneumoniae isolates to common antibiotics, hence, there is an urge for revisiting the antibiotic therapy protocols for prevention and control of the spread of resistant bacteria.

    Keywords: Carbapenem Resistance, Klebsiella pneumoniae carbapenemases, blaKPC, blaGES, Real-Time PCR
  • Seyed Abolfazl Hosseininasab Nodoushan, Sharareh Moghim, Nasrin Mirzaei, Hajieh Ghasemian Safaei* Page 2
    Background

    Pseudomonas aeruginosa is among the top 10 resistant bacteria worldwide. Its extraordinary resistance is principally due to the function of quorum sensing genes, such as lasR and pqsR, which are mainly involved in antibiotic resistance.

    Objectives

    This study aimed to examine possible mutations in lasR and pqsR in resistant clinical isolates of P. aeruginosa.

    Methods

    We obtained 120 suspected isolates of P. aeruginosa from burn patients. The isolates were identified by biochemical tests and toxA gene analysis. The PCR products of LasR and PqsR genes were analyzed in seven resistant isolates. Then, the sequences were compared with a reference strain.

    Results

    We verified Ninety-six isolates as absolute P. aeruginosa. According to antibiograms, 95.8% of the isolates were considered as multidrug-resistant, of which 87.5% were extensively drug-resistant. Based on DNA and protein sequences, only one missense mutation was observed, including R180Q in lasR and A314V in pqsR. While R180Q decreased the stability of LasR and had a deleterious impact on protein function, A314V had a neutral impact on the protein and increased PqsR protein stability. Also, two nonsense mutations in position E259 were observed in the PqsR protein.

    Conclusions

    The lasR and pqsR genes possibly can play a key role in antibiotic resistance, but they are not the only factors. Hence, studying mutations helps design a promising antibiotic to overcome antibiotic resistance as much as possible.

    Keywords: Pseudomonas aeruginosa, Drug Resistance, Genes Regulator
  • Daqiang Wu, Qiangjun Duan, Ganfei Xu, Yan Guan * Page 3
    Background

    Staphylococcus epidermidis is an important opportunistic pathogenic bacterium causing infections on implanted medical devices by biofilm formation. Sodium houttuyfonate (SH), which is the active modified compound of Houttuynia cordata is commonly applied for treating chronic bronchitis, purulent skin infections, and respiratory tract infections in China.

    Objectives

    We aimed to investigate the in vitro effects of SH in combination with erythromycin on the production of IcaA and expression of icaA to shed the light on the mechanism of SH and erythromycin in inhibiting biofilm formation of S. epidermidis.

    Methods

    The morphology of the biofilm of S. epidermidis was examined under a scanning electron microscope. Furthermore, inhibitory effects of SH and erythromycin on the production of IcaA and the expression of icaA were detected by Western blotting and quantitative reverse transcription PCR, respectively.

    Results

    First, the morphological results indicated that combing SH and erythromycin at sub-MIC concentrations can effectively inhibit biofilm formation of S. epidermidis. Furthermore, our presented results showed that combing SH and erythromycin at sub-MIC concentration can significantly downregulate the expression of icaA and repress the protein production of IcaA at irreversible attachment and maturation stages of biofilm formation of S. epidermidis.

    Conclusions

    Therefore, our findings suggest that the potent antibiofilm activity of SH in combination with erythromycin against S. epidermidis may be partially due to inactivation of icaA.

    Keywords: Natural Product, Sodium Houttuyfonate, Biofilm, Staphylococcus epidermidis, IcaA
  • Yue Fang, Yuzhu Song, Chao Li, Guangying Yang, Rui Zheng, Yaoqiang Shi, Xueshan Xia * Page 4
    Background

    Staphylococcus aureus and coagulase-negative staphylococci are highly antibiotic-resistant pathogens and exhibit multiple virulence factors that threaten public health. However, few reports have evaluated the resistance and virulence of staphylococci in community settings.

    Objectives

    This study surveyed the epidemiology, antimicrobial resistance, and virulence genes of staphylococci in the densely-populated university town of Kunming in Southwestern China.

    Methods

    Various strains were isolated from hand-touching surfaces in Chenggong University Town, China, and identified via 16S rRNA sequencing. Staphylococci were isolated, and drug resistance was determined via antibiotic sensitivity testing. The mecA gene was verified and typed. Twelve virulence-associated genes and several disinfectant-resistance genes were determined.

    Results

    One hundred sixty-three strains were collected from hand-touching surfaces, and more than a quarter of the isolates (46/163, 28.22%) were identified as staphylococci. Among the staphylococcal strains, 19 (41.30%) showed multidrug resistance, with resistance rates of more than 40% to benzyl-penicillin, erythromycin, oxacillin, and tetracycline. Twenty isolates (43.48%) carried mecA, and most staphylococcal cassette chromosome mecs (SCCmecs) were nontypeable. Twenty-eight strains (60.87%) carried at least one virulence gene; hemolysin genes were the most prevalent, and 22 strains (47.83%) carried qac genes. Staphylococcus aureus strain ST59 carried multiple resistance and virulence genes.

    Conclusions

    Resistant staphylococci can easily adhere to hand-touching surfaces. More attention should be given to the appearance of resistance and virulence gene-harboring staphylococci in community settings. The findings herein suggest that effective disinfectant strategies and feasible surveillance measures are urgently needed.

    Keywords: Hand-Touching Surface, Staphylococci, Virulence, Resistance, mecA
  • Jun Zou, Xiaoying Yang, Lingbing Zeng, Xingxing Wang, Yanling Liu, Dandan Wei, Xuefei Hu, Niya Hu * Page 5
    Background

    Anaerobic infections have been reported for many years, and there is an increasing trend in these infections worldwide, but anaerobic infections have not received sufficient attention. Rapid identification is important for the treatment of anaerobes because of their different antibiotic-resistance profiles.

    Objectives

    This study aimed to analyze the hospital’s present condition to improve anaerobic culture detection rates and enhance the monitoring of anaerobes in hospitals.

    Methods

    This study retrospectively analyzed sterile body fluids sent to the First Affiliated Hospital of Nanchang University in the form of culture bottles in 2017. Finally, 28 strains of obligate anaerobes were isolated, then combined 16S rRNA gene sequencing and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry was used to identify the strains and performed separate antimicrobial susceptibility testing.

    Results

    The results showed that these two methods are highly consistent. There were 17/28 (61%) Gram-negative and 11/28 (39%) Gram-positive bacteria. The predominant bacteria were Bacteroides fragilis (15/28). Ten strains were isolated from the Obstetrics and Gynecology Department. The next most frequently affected departments were General Surgery (17.86%) and the ICU (17.86%). We analyzed the resistance to penicillin, cefoxitin, clindamycin, metronidazole, meropenem, piperacillin/tazobactam and amoxicillin/clavulanic acid by using the agar dilution method. The resistance rates to clindamycin were relatively high but relatively sensitive to metronidazole.

    Conclusions

    The results of this research indicate that we should pay attention to the cultivation of anaerobic bacteria, especially in certain high-risk departments.

    Keywords: Anaerobic Bacteria, Identification, Antimicrobial Susceptibility
  • Alireza Sedaghat, Majid Khadem Rezaiyan *, Ali Ahmadabad, Hassan Abbaspour, Masoud Youssefi, Mohammad Moein Shirzad, Mohammadhossein Esfahani, Mohammad Mirzaei, Mohammad Ramezani Page 6
    Background

    Globally, Acinetobacter spp., most commonly, Acinetobacter baumannii, are one of the most common Gram-negative nosocomial infections, especially in Intensive Care Units (ICUs) and burn wards. Because of the pathogens’ ability to survive for a long time, the eradication of the pathogen from these wards remains a great concern. Simultaneously, the remarkable increase in antibacterial resistance among A. baumannii strains in recent years has raised a great deal of concern.

    Objectives

    The study assessed the prevalence and antibacterial resistance pattern of A. baumannii in the only academic-affiliated burn center in northeastern Iran in 2012-2014.

    Methods

    In this cross-sectional study, 5,080 samples from patients admitted to two burnt wards and one burn ICU were included. The samples were from different sources including wound tissue, blood, bronchial secretion, and urine. The antibacterial resistance pattern was determined using relevant antibiotics based on the Clinical and Laboratory Standards Institut (CLSI) instructions.

    Results

    Acinetobacter spp. were found in 39% of the acquired cultures (1,985 out of 5,080) and 51.9% of bacterial positive cultures (1985 out of 3823). The resistance rate of Acinetobacter spp. against antibiotics varied from 0.9% for colistin to 100% for piperacillin-tazobactam. All Acinetobacter spp. were multidrug-resistant (MDR) due to considerable resistance to fluoroquinolones (95%), cephalosporins (93% - 98%), penicillins (97%), carbapenems (94% - 95%), and beta-lactamase inhibitors (87% - 100%).

    Conclusions

    Given that infections are a major cause of mortality in burn wards, the high prevalence of MDR isolates of Acinetobacter spp. in this burn center suggests that local antibiotic prescription policies should be revised and infection control strategies should be improved. Also, antibiotic cycling and restrict infection control strategies should be implemented in high-risk wards such as burn units.

    Keywords: Antimicrobial Drug Resistance, Acinetobacter baumannii, Burn Units