Showing 10 results for Subject: bacteriology
Seyed Amin Enayatzadeh Meymandi, Laleh Babaeekhou, Maryam Ghane,
Volume 13, Issue 5 (9-2019)
Abstract
ABSTRACT
Background and Objectives: Emergence and spread of multidrug-resistant (MDR) and extensively-drug resistant (XDR) Pseudomonas aeruginosa strains could complicate antipseudomonal chemotherapy. Dissemination of resistance genes, such as β-lactamases encoding genes by horizontal gene transfer can lead to development of multi-drug resistance in P. aeruginosa. The purpose of this study was to investigate the latest resistance patterns in MDR and XDR strains and evaluate Ambler class A β-lactamase gene distribution in P. aeruginosa clinical isolates.
Methods: One hundred molecularly and biochemically identified P. aeruginosa strains isolated from different clinical specimens were tested for sensitivity to 17 antibiotics using the Kirby-Bauer disk diffusion method. PCR was performed to detect bla TEM-1, bla SHV-1, bla REP-1 and bla VEB-1 genes. Results were analyzed using SPSS and NTSYSpc softwares.
Results: Based on the results of antibiogram, the highest rate of resistance was observed against amikacin (100%), aztreonam (83%), ceftazidime (55%), cefepime (55%) and netilmicin (48%). In addition, the frequency of MDR and XDR isolates was 95% and 5%, respectively. The blaSHV-1, bla TEM-1, bla PER-1 and bla VEB-1 genes were detected in 31%, 24%, 13% and 10% of the isolates, respectively.
Conclusion: Antibiotic resistance to β-lactam antibiotics and frequency of β-lactamase genes were relatively high in the study area. We also found that a significant proportion of XDR strains with different antibiotic resistance profile is isolated from tracheal specimens.
KEYWORDS: Pseudomonas aeruginosa, Beta-Lactamase, Multidrug Resistant, Extensively Drug Resistant.
Mina Eghbali, Majid Baserisalehi, Masood Ghane,
Volume 14, Issue 3 (5-2020)
Abstract
Background and Objectives: Moraxella catarrhalis is considered as an emerging pathogen and a new nosocomial infection agent. This study was conducted to isolate and identify M. catarrhalis from clinical samples (respiratory tracts) and assess them for antimicrobial susceptibility patterns.
Methods: In total, 280 samples were collected from patients with respiratory tract infection, and 120 samples were obtained from healthy individuals in the control group. The isolates were identified by phenotyping and genotyping methods, and their antibiotic susceptibility was evaluated using disk diffusion methods. The presence of β-lactamase and efflux pump activity were specified via phenotypic methods. Finally, Bro and acrA genes in the isolates were detected by PCR technique.
Results: The frequency of this bacterium was 9.64% (27 out of 280) in patients with respiratory tract infection and 4.16% (5 out of 120) in the control group. Although the isolates were resistant to penicillin, they had various responses against other antibiotics. The results obtained from molecular method showed that 90.6% and 84.3% of the isolates possessed Bro and acrA genes, respectively. There was a significant relationship (P<0.05) between the presence of Bro and acrA genes and antibacterial resistance to ampicillin, amoxicillin, cefazolin, cefuroxime, and chloramphenicol.
Conclusion: Our findings confirmed the existence of M. catarrhalis in patients with respiratory diseases and the high prevalence of antibiotic resistant genes in M. catarrhalis isolates. Therefore, timely diagnosis and successful treatment can play important roles in preventing their spread.
Fahimeh Azadi, Masoomeh Rezanezhadi, Hanieh Bagheri, Laith B Alhusseini, Hamid Reza Joshaghani,
Volume 15, Issue 4 (7-2021)
Abstract
Background and objectives: Tuberculosis (TB) is a serious public health problem and a significant diagnostic and therapeutic challenge worldwide. Molecular diagnostic techniques are crucial parts of the World Health Organization’s new tuberculosis control strategy. This study aims to identify Mycobacterium tuberculosis and rifampin resistance in pulmonary and extra-pulmonary clinical specimens using the Gene Xpert MTB/RIF assay.
Methods: The study was carried out on 220 specimens from pulmonary and extra-pulmonary TB patients that were sent to the Kavosh Laboratory in Gorgan (Iran) during 2018-20. The Gene Xpert MTB / RIF method was applied to detect M. tuberculosis and rifampin resistance.
Results: Of 220 specimens, 15 (6.81%) were found to be positive, four (26.6%) of which were related to pulmonary and 11(73.3%) to extra-pulmonary specimens. None of the positive samples was resitant to rifampin according to assay.
Conclusion: Our findings demonstrate that the Gene Xpert MTB/RIF is able to accurately detect M. tuberculosis in pulmonary and extra-pulmonary specimens. The accurate and early diagnosis of TB infection allows timely therapeutic intervention, which is beneficial not only for the patient but also for possible contacts.
Behnoush Khasheii, Pezhman Mahmoodi, Abdolmajid Mohammadzadeh,
Volume 15, Issue 5 (9-2021)
Abstract
Increasing antibiotic resistance is a global health problem. In recent years, due to the indiscriminate use of antibacterial compounds, many bacterial pathogens, including staphylococci, members of the
Enterobacteriaceae family including
Klebsiella pneumoniae and bacteria such as
Pseudomonas aeruginosa and
Acinetobacter baumannii have become multi-drug resistant. Consequently, it is important to explore alternative approaches for eliminating resistant strains. Bacteria synthesize low-weight molecules called siderophores to chelate iron from the environment as a vital element for their growth and survival. One way to deal with resistant bacterial strains is to utilize siderophore-mediated iron uptake pathways as entrance routes for drug delivery. Therefore, the production of drugs with Trojan horse strategy in the form of conjugated siderophore-antibiotic complexes has recently received much attention
for dealing with resistant isolates.
In this review, we discuss the efficacy of siderophore-antibiotic conjugates as a Trojan horse strategy for eliminating drug-resistant pathogens.
Maryam Rafiee, Alijan Tabarraei, Mahsa Yazdi, Alireza Mohebbi, Ezzat Allah Ghaemi,
Volume 17, Issue 2 (3-2023)
Abstract
Background and objectives: Urinary tract infection (UTI) is one of the most common bacterial infections. Staphylococcus saprophyticus is a common Gram-positive bacterium that causes uncomplicated UTIs in women. The present study aimed to study the drug resistance pattern and phenotypic and genotypic variation of S. saprophyticus isolates from women with UTI in Gorgan, northern Iran.
Methods: This study was performed from May 2018 to September 2020. During this time, 35 S. saprophyticus strains were isolated from patients with UTI. The antimicrobial patterns of the isolates were determined by a conventional method. Phenotypic criteria such as pigment production, mannitol fermentation, urease production, and 16SrRNA gene valuation were studied.
Results: All isolates were sensitive to nitrofurantoin, gentamicin, and linezolid. S. saprophyticus isolates showed the highest level of resistance to penicillin (85.7%) and erythromycin (51.4%). A variation was detected among S. saprophyticus isolates in terms of pigment production i.e. about 51.4% showed yellow pigment in Muller Hinton agar, and 62.9% of the isolates were able to ferment mannitol sugar. Of 11 isolates that were sequenced for the 16SrRNA gene, only two isolates showed different patterns.
Conclusion: Nitrofurantoin and trimethoprim-sulfamethoxazole are the antibiotics of choice for the treatment of UTI caused by S. saprophyticus in the study area. Due to the phenotypic and genotypic differences among S. saprophyticus isolates, typing of S. saprophyticus at the subspecies level is recommended.
Sadaf Khursheed Baba, Abiroo Jan, Mohd Suhail Lone, Dalip K Kakru, Bashir Ahmad Fomda, Gulnaz Bashir, Nadeem Ahmad Bhat,
Volume 17, Issue 3 (5-2023)
Abstract
Background and objectives: Conventional culture and sensitivity methods take around 48 hours to generate antibiotic sensitivity results after a blood culture is flagged as positive by automated systems. However, it is imperative to initiate early targeted antibiotic therapy for effective management of sepsis and to reduce morbidity, mortality, and cost of treatment. This study aimed to evaluate the direct sensitivity test (DST) as a potential tool to obtain quicker antibiotic susceptibility results from positive BacT/ALERT blood culture vials and the VITEK-2 system (the reference method).
Methods: Blood culture bottles flagged as positive by BacT/ALERT were Gram-stained. Cultures with polymicrobial growth were excluded from the study. The isolates were then simultaneously cultured and processed for the DST using the disk diffusion method. Agreements or errors were interpreted according to the Clinical and Laboratory Standards Institute’s guidelines.
Results: Among 76 Gram-positive isolates, we observed 99.2% essential agreement between the DST and AST. The rate of minor and major errors was 4.04% and 1.18%, respectively. Among 75 Gram-negative isolates, we observed 98.99% essential agreement between the DST and AST. The rate of minor and major errors was 4% and 2%, respectively. No very major error was seen in either Gram-negative or -positive isolates.
Conclusions: The DST results are available earlier than the AST results, which can ultimately help in the early initiation of targeted antibiotic therapy.
Arvin Shajeie, Mehrnaz Rad, Mahdi Askari, Kamran Sharifi, Gholamreza Hashemi Tabar,
Volume 17, Issue 5 (9-2023)
Abstract
Background: Colistin is the most significant last-line antibiotic for the treatment of multidrug-resistant infections caused by Gram-negative bacteria, especially the Enterobacteriaceae family. The emergence and rapid spread of the plasmid-mediated resistance gene, mcr-1 (mobilized colistin resistance), in some isolates of Escherichia coli in recent years provoked public health concerns since it has been shown that mcr-1 with other resistance genes, such as ESBLs (extended-spectrum beta-lactamases) and carbapenemases, could be carried on a single plasmid concurrently. The excessive consumption of colistin, particularly in the livestock industry, and the transmission of these resistant bacteria from livestock to humans may potentially increase the risk of the spread of resistance in humans. Therefore, this study aimed to detect the prevalence of mcr and carbapenem resistance genes among neonatal calves in Mashhad, Razavi Khorasan Province, Iran.
Methods: In the current study, 200 fecal samples from healthy and diarrheic neonatal calves (≤35 days old) were collected in Mashhad (190 E. coli strains were isolated). Antibiotic susceptibility to ceftazidime, cefepime, cefixime, meropenem, colistin, and ciprofloxacin was examined. The double-disk diffusion method (ceftazidime + ceftazidime/clavulanic acid) was performed on Mueller-Hinton agar (MHA) media to phenotypically distinguish the ESBL producers. Afterward, the Multiplex polymerase chain reaction (PCR) method was used to detect colistin resistance genes (mcr-1, mcr-2, mcr-3, mcr-4, and mcr5), NDM-1 (New Delhi metallo-beta-lactamase 1), and OXA-48 as carbapenemases.
Results: The results of the resistance rate to antibiotics were cefepime, ceftazidime, cefixime, meropenem, and colistin. Based on the findings, 33.7% were phenotypically ESBL producers, 4.21% harbored mcr-1, and no NDM-1 or OXA-48 was detected. Among the mcr-1-positive isolates, 5 strains showed the ESBL phenotype.
Conclusion: The results highlight the need for continued monitoring of antibiotic resistance in livestock and the potential for transmission to humans. The findings also underscore the importance of responsible antibiotic use in both human and animal health to mitigate the spread of antibiotic resistance.
Fatemeh Rashedi, Zahra Yazdanpour, Farzad Khademi, Hamid Vaez,
Volume 17, Issue 6 (11-2023)
Abstract
Background: Urinary tract infection (UTI) is one of the most prevalent bacterial diseases worldwide. Escherichia coli is a well-known etiological agent of UTI. The emergence and spread of metallo-beta-lactamase (MBL)-producing E. coli is a serious threat to public health.
This study aimed to investigate the antibiotic resistance pattern and prevalence of MBL-producing E. coli isolated from UTI.
Methods: From January 2020 to June 2021, 1200 urine specimens were collected from patients suspected of having UTI. Antibiotic susceptibility testing was carried out by the disk diffusion method. The prevalence of MBL (blaVIM, blaIMP, blaSPM, and blaNDM) genes was determined by the polymerase chain reaction (PCR) method.
Results: The highest susceptibility was observed against amikacin (96%) and gentamicin (95%). The isolates were mostly resistant against ampicillin (72%) and cephalothin (60%). All carbapenem-resistant isolates were MBL-positive. Based on the results of PCR, 75% of the isolates were blaNDM-positive.
Conclusion: Resistance to some antibiotics, such as ampicillin and cephalothin, was high, and their prescription must be restricted. The prevalence of MBL-producing isolates was not high; however, due to the high level of resistance against other antibiotics, continuous monitoring of MBL-producing isolates is highly essential.
Manasa Sireesha Devara, Sriushaswini Bhamidipati, Vijaya Bharathi Dondapati , Narasinga Rao Bandaru,
Volume 17, Issue 6 (11-2023)
Abstract
Background: Medicinal plants have played crucial roles in the traditional health care system since the origin of mankind. Among them, cinnamon is used not only as a spice in food but also as a substance with many health-beneficial effects. The aim of the present study was to identify the antibacterial activity of cinnamon bark extract against bacterial isolates from patient pus samples that might help treat infections.
Methods: The antibacterial potential of cinnamon bark extract in both ethanol and methanol against 6 bacterial isolates obtained from pus samples received in the Microbiology Laboratory was identified by agar well diffusion, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC) using standard techniques.
Results: By agar well diffusion, the highest inhibitory activity of ethanol and methanol extracts of cinnamon was shown by Staphylococcus aureus, followed by coagulase-negative Staphylococci. The lowest inhibitory effect was shown by Proteus mirabilis. The ethanol extract of cinnamon MIC and MBC ranged from 6.25 mg/mL to 12.5 mg/mL and 12.5 mg/mL to 50 mg/mL. The methanol extract of cinnamon MIC showed a value of 12.5 mg/mL, and the methanol extract of MBC ranged from 12.5 mg/mL to 50 mg/mL against all bacterial isolates of the present study.
Conclusion: Staphylococcus aureus is sensitive to the alcoholic extract of cinnamon bark, but its effect is less than that of the selected antibiotic.
Abolfazl Shirdel Abdolmaleki, Abolfazl Rafati Zomorodi, Mohammad Motamedifar, Yalda Malekzadegan,
Volume 18, Issue 1 (1-2024)
Abstract
Background: Urinary tract infection (UTI) is one of the most common bacterial infections of all ages and sexes. Escherichia coli is reported as the most common predominant pathogen. Urinary tract infection treatment leads to abundant antibiotic application in hospitals and communities, continuously developing multidrug resistance (MDR). This study aimed to determine the sensitivity and resistance pattern to common antibiotics among E. coli isolates from patients with UTIs at Nemazee Hospital in Shiraz.
Methods: This retrospective cross-sectional survey studied 1910 positive urine samples with E. coli bacteria from patients referred to Nemazee Hospital from 2018 to 2019. Antimicrobial susceptibility testing was performed on 12 commonly used antibiotics for UTIs.
Results: A total of 1910 E. coli isolates were gathered during these 2 years. The most highlighted resistance was observed against quinolones and cephalosporins at 86.9% and 89.7%, respectively. Cephalexin (87.9%) and nalidixic acid (86.1%) have shown the lowest activity against E. coli isolates. Also, the highest susceptibility was determined for amikacin (88.3%), nitrofurantoin (76.8%), and gentamicin (70.6%). In addition, 1624 (85%) isolates were MDR.
Conclusion: In conclusion, resistance to antibiotics (such as ciprofloxacin, norfloxacin, tetracycline, cefotaxime, and nitrofurantoin) is increasing. Therefore, it is vital to follow an appropriate antimicrobial stewardship program.
