Medical Laboratory Journal
Volume:8 Issue: 4, 2014

Vancomycin is used for treatment of methicillin-resistant S. Aureus (MRSA) infections; therefore، resistance to this antibiotic is increasing. We aimed to determine the antibiotic resistance pattern and frequency of vancomycin resistant S. Areas (VRSA) strains isolated from clinical samples. In this cross-sectional study، 100 S. Aureus isolates collected from hospitals in Shiraz during six months، 2012، were identified by biochemical، microbiological and molecular methods. After determination of antibiotic susceptibility pattern by disc diffusion method and vancomycin agar screening test، Minimum Inhibitory Concentration (MIC) was determined by E-test for vancomycin، thicoplanin، linezolid and quinupristin-dalfopristin. The most resistant and the most sensitive antibiotic were ampicillin (%95) and quinupristin-dalfopristin (99%)، respectively، and 44% of isolates were resistant to methicillin. In agar screening test، 48% of strains had reduced sensitivity and in disc diffusion 3% strains were resistant to vancomycin. In E-test method، only one isolate was resistant to vancomycin. given the presence of VRSA and new antibiotic resistant strains، we recommend doing some intervention to prevent from spreading these strains in hospitals..

Increasing prevalence of methicillin resistant Staphylococcus aureus strains (MRSA) with their multidrug resistance potential causes difficulties in the treatment of infections due to these bacteria. Hence, the detection and determination of the frequency of MRSA strains via phenotypical and molecular methods is necessary in different parts of the county. In this cross- sectional study, 150 Staphylococcus aureus strains were collected from different clinical samples in the hospitals located in Shiraz and Jahrom, Iran. To detect methicillin resistant Staphylococcus aureus strains, we used phenotypical methods such as disc diffusion and minimum inhibitory concentration by E-Test, and PCR molecular method for mass gene. The frequency of methicillin resistant Staphylococcus aureus was 63 strains (42%) using disc diffusion and E-Test. while in PCR method, in addition to 63 strains, nine other isolates, which were sensitive to oxacillin by disc diffusion and E-Test, possessed also mecA gene. By and large, 72 isolates (48%) had methicillin resistance gene. Given the results of phenotypical and molecular methods, the frequency of methicillin resistant Staphylococcus aureus was relatively high in this area. Thus, the MRSA strains can be detectable as soon as possible by accurate and sensitive methods such as PCR to determinate the effective antibiotics.

Multiple drug resistance has increased in recent years in Klebsiella pneumoniae isolates. The Integrons are mobile genetic elements that carry antibiotics resistance genes. The aim of this study was to determine antibiotic susceptibility and the prevalence of class 1, 2, and 3 integrons in clinical Klebsiella pneumoniae isolated from clinical specimens. A total of 108 K. pneumoniae isolates were collected between April and December 2011 from different clinical specimens of Loghman hospital in Tehran and identified by biochemical tests. Susceptibility of isolates to 14 antibiotic disks was determined by disk diffusion method. The template DNA was extracted by freeze-thaw method and the presence of class 1, 2, and 3 integrons was investigated by PCR method. Level of resistance to antibiotics in integron-positive and integron-negative isolates was determined. The highest level of resistance was seen for cefotaxime, ceftriaxone, and amoxicillin-clavulanic acid (55.5%). In 79 isolates (73.14%) class 1 integron and in 57 of 79 isolates (72.15%) resistance to at least two classes of drugs were seen. The class 2 and 3 integrons were not detected. Among integron-negative isolates, 8 isolates (27.58%) had resistance to at least one antibiotic. The prevalence of class 1 integron in resistant K. pneumoniae is high; therefore, the monitoring of drug resistance and limiting the use of antibiotics are necessary.

In the past, most strains of E. coli were susceptible to a wide range of antimicrobial agents, but this situation is now changed by indiscriminate use of antibiotics. Ceftriaxone and Ceftazidime are the most current antibiotics used for Enterobacteriaceae infections in hospitals. The aim of this study was to determine antimicrobial resistance of Escherichia coli strains isolated from patients. During a 12-month period, 200 clinical samples taken from patients referred to Zahedan hospitals were assessed to isolate Escherichia coli. Antibiotic susceptibility was determined by disk diffusion method and micro-broth dilution; and Bla TEM resistance genes were detected by PCR. Following phenotype verification testing, 112 isolates (56%) were produced Extended Spectrum Beta Lactamase (ESBLs) and 130 isolates were potential producers of beta-lactamase (ESBL). Using PCR, 72 isolates (38.55%) have TEM gene. The rate of antibiotic resistance of Escherichia coli isolates to ceftriaxone and ceftazidime is high; therefore, it seems reasonable to do antibiogram before treatment.

Listeria monocytogenes is a bacterium transferred by foods and is the agent of many sporadic and epidemic diseases in humans. This study aimed to investigate the prevalence of L. monocytogenes and to determinine their antibiotic resistance profile in red meats. this cross-sectional study was performed on 400 red meat samples obtained from industrial slaughterhouses placed in Kerman, Iran. First, the samples were enriched with Simultaneous Enrichment Broth (SEB), and then plated onto Palcam agar and Tryptic Soy Broth Yeast Extract Broth (TSAYE). After identification of the isolates based on biochemical tests and PCR, the isolates were checked for their antibiotic resistance profile using disk Diffusion. of 400 samples, 12 samples (3%) were contaminated with different species of Listeria. Using PCR, hly gene was recognized in eight samples (2%) of L. monocytogenes. Furthermore, there was a significant difference in isolation rate of lamb samples compared to cow ones. While all of the isolates were resistant to clindamycin, amikacin and chloramphenicol, they were sensitive to penicillin. in spite of low rate of infection in red meat samples in Kerman city, due to high risk of Listeria contamination in red meats, we recommend applying a routine screening to identify this bacterium in our county.

some of predisposing factors for enterococci colonization are hospitalization in ICU, prolonged use of antibiotics and continued bed rest in hospital. In this study antibiotic resistance of enterococcus in hospitalized patients of four hospitals in Tehran were studied. the Clinical samples were taken from patients admitted to the ICU, from September 2011 to April 2012. Enterococci isolates were confirmed by biochemical tests, and Enterococcus faecalis and Enterococcus species by species-specific ddl genes. The disk diffusion and micro agar dilution susceptibility tests were performed according to Clinical and Laboratory Standards Institute (CLSI). of 41 isolates in ICUs, 22 (5.52%) were E. faecium and 19 (5.47%) were E. faecalis. Most of E. faecium was isolated from urine and E. faecalis from trachea specimens. The rate of resistance to vancomycin, ampicillin, gentamicin, chloramphenicol and nitrofurantoin in E. faecium isolates was more than that of E. faecalis and the rate of resistance to tetracycline, ciprofloxacin and erythromycin was the same in both of them. MIC50 in vancomycin and ampicillin resistant E. faecium isolates was greater than 256 microgram and the MIC50 in gentamicin resistant isolates was more than 1024 microgram. The presence of multi-resistant E. faecium strains in ICUs can be a serious warning for physicians and patients.

Escherichia coli is the most common cause of urinary tract infections in children and the leading cause of intra-abdominal infections (peritonitis and abscess) followed intestinal injuries. Urinary tract infection, including cystitis and pyelonephritis, is a common childhood infection. E. coli causes more than 90 percent of the community acquired and 50% of hospital acquired urinary tract infections; therefore, the determination of E. coli antibiotic susceptibility is a paramount importance to clinical and epidemiological purposes. In this cross-sectional study, 50 E. coli strains isolated from urine samples of children less than 7 years of age with urinary tract infections. They were compared for drug susceptibility testing by disc diffusion method with 50 strains of Escherichia coli isolated from stool samples of healthy children with the same age and sex pattern. The actual amount of drug sensitivity of uropathogenic and intestinal Escherichia coli strains to amikacin was 94 and 100%, nitrofurantoin 90 and 88%, gentamicin 66 and 94%, cefixime 56 and 60%, nalidixic acid 38 and 44% and to cotrimoxazole 28 and 32%, respectively. the rate of resistance to gentamicin, Cefixime and nalidixic acid in urinary tract infection isolates were more than intestinal strains. The highest rate of drug resistance in urinary Escherichia coli isolates was associated with cotrimoxazole and the lowest one with amikacin.

One of the main causes of increased mortality in cancer patients is bacteremia. On the other hand, antibiotic resistance is the major cause of treatment failure in malignant diseases especially in hematological malignancies. The aim of this study was to diagnose the bacterial strains isolated from blood specimens of cancer patients and to determine their antibiotic susceptibility. In this cross-sectional study, 0.5 ml of venous blood was taken from 613 cancer patients especially leukemia, and blood cultures and antibiotic susceptibility tests were performed using standard methods. Using disc diffusion method, antibiotic susceptibility was performed with a wide range of antibiotics. Out of 613 cultured specimens, 153 (25%) were found to be positive including 76.47% of gram negative and 23.53% of gram positive bacteria. The most common isolated bacteria were E. coli, coagulase-negative Staphylococci, Klebsiella, Staphylococcus aureus and Pseudomonas aeroginosa, respectively. It seems that Ceftriaxone is the best choice for the treatment of gram negative caused bacteremia and Gentamicin for bacteremia caused by gram positive agents. Given the high level of resistance to the commonly used antibiotics, it seems reasonable to avoid of early and inappropriate use of antibiotics to prevent the development of drug resistant bacteria.

Bachground and most of environmental microorganisms have the genes resistance to antibiotics and metals. The aim of the current study was to survey resistance pattern to some antibiotics and heavy metals in three pseudomonas aeruginosa isolated from different ecological areas. first, the isolates were identified by biochemical methods and phylogenetic analysis. Then, the evaluation of antibiotic resistance was conducted by disc diffusion and that of Heavy metal resistant by agar dilution, in a range of 50-500 µg/ml. The results showed that all three isolates were resistant to beta lactam antibiotics. Although these isolates were highly resistant to heavy metals, no relationship was observed between ecological sources and the resistance pattern in ICT1 and Abt2 strains. However, strain Q isolated from digestive system of ParmacellaIberica showed high resistance to antibiotics and low resistance to heavy metals. given that environmental bacteria have a high potentiality for carrying resistance genes and this can be an advantage environmentally, they could be used to remove heavy metals from polluted areas. On the other hand, resistance genes medically are a concern due to probability of transferring to pathogen strains.

Enterococci are normal flora of human body and considered as the third leading cause of nosocomial infections. The aim of this study was to determine drug resistance of Enterococcus species through biochemical methods. One hundred twenty-eight of enterococcus suspected samples were isolated from gorgan and gonbad’s hospitals from April to June, 2013. The samples were cultured on blood agar, chrome-agar, EMB agar and some special cultures of isolation of Enterococcus species. Suspension of bacteria was grown in Mueller Hinton agar and the inhibition zone diameter was determined by disk antibiogram. Of 128 samples, 109(85.15%) were enterococci faecalis and 19 (14.85%) Enterococcus Faecium. In all of 128 cases, eight showed resistance to amoxicillin, ten to ampicillin, five to gentamicin, five to ciprofloxacin, six to chloramphenicol, four to cephalexin and one to vancomycin. It seems to be necessary to use drug sensitivity test for having appropriate treatment and preventing from resistance strains.

Streptococcus pneumoniae is the most common cause of acquired bacterial infections in the respiratory system. In recent years, a high incidence of pneumococcal resistance to different antibiotics has also been appeared. This study was conducted to evaluate the in vivo and in vitro resistance of pneumococcal pneumonia to ceftriaxone, azithromycin and co-amoxiclave in clinical setting and laboratory. In this single-blind clinical trial study, the participants were the patients with the diagnosis of pneumonia referred to infectious diseases clinic in Vali-e-Asr hospital of Birjand university of Medical Sciences, October 2012 - April 2014. The patients were randomly allocated to one of the three therapeutic regimes including azithromycin, ceftriaxone, and co-amoxiclave. After 48-72 hours that the infection was confirmed by paraclinical findings, the patients with pneumococcal pneumonia remained in the study and their in vivo and in vitro resistance to the above mentioned antibiotics were compared. The most in vitro drug resistance was to co-amoxiclave (41.5%) and the least to ceftriaxone (20.8%) (P>0.05). For In vivo, the most resistance was to azithromycin (47.4%) and the least one to ceftriaxone (6.7%) (p<0.05). The agreement coefficient between the laboratory antibiogram test and the clinical responses to therapeutic regimes of azithromycin, co-amoxiclave and ceftriaxone was 0.25 (p=0.26), 0.46 (p=0.02) and 0.44 (p=0.04), respectively. With regard to the demographic characteristics of the patients in this study, the resistance of Streptococcus pneumoniae to ceftriaxone is less than that of co-amoxiclave and azithromycin in both clinical setting and laboratory.

Group B streptococcus is one of the agents leading to infantile blood infection and meningitis as well as aggressive infections in pregnant women. The vast use of antibiotics in order to prevent from the diseases caused by this bacterium has led to some concerns about the emergence of drug resistance in Group B streptococcus. Thus, we aimed to investigate Group B streptococcus drug resistance patterns to aid appropriate drug prescriptions. The study was conducted on 268 pregnant women. Having been transferred to Todd Hewitt broth, the samples were cultured on blood agar and the identity of Group B streptococcus was confirmed through biochemical tests (gram stain tests, the catalase test, CAMP, and sodium hippurate hydrolysis). Of 268 samples, 14 (5.2 percent) showed positive Group B streptococcus culture. All cases (100 percent) were resistant to penicillin, eight (57.15 percent) to erythromycin, 13 (92.2 percent) to clindamycin, three (7.1 percent) to Cefazolin, seven (50 percent) Ceftizoxime and four (28.57 percent) were resistant to Cefotaxime. Three (21.4 percent) were semi-sensitive toward Cefazolin. No resistance was observed toward ampicillin or Vancomycin. The rate of B streptococcus drug resistance to various antibiotics has increased in Iran.

The prevalence of different bacterial species and antibiotic resistance varies according to geographical conditions. Hence, we aimed to identify the prevalence of bacterial agents isolated from the urine culture and also investigate the antibiotic susceptibility of bacteria. This cross-sectional study conducted on 7200 urine samples to identify the bacteria causing infections, using differential tests. The antimicrobial susceptibility was performed via disk diffusion method according to the Clinical and Laboratory Standards Institute (CLSI). The most common bacteria were Escherichia coli (736; 61.1%) and Klebsiella pneumonia (128; 10.6%) and Enterococcus faecalis, (88; 7.3%). The highest antibiotic susceptibility was related to Ciprofloxacin (174; 14.45%) and the lowest to Amoxicillin (795; 62.02%). Owing to the lowest resistance, it is recommended that Ciprofloxacin be used as the first line of treatment. In addition, Amoxicillin and Ampicillin should be used the least during primary treatment of urinary tract infections.

Klebsiella pneumoniae is an opportunistic nosocomial pathogen causing a variety of infections including urinary tract infections, pneumonia, septicemia, wound infections and infections in the intensive care units. Since the ESBL producing Klebsiella pneumoniae strains are increasingly causing urinary tract infections, we aim to assess antibiotic resistance pattern and evaluate the prevalence of ESBL in Klebsiella pneumoniae isolated from urinary tract infections. this cross-sectional study was conducted on 122 Klebsiella pneumoniae strains collected from Zahedan hospitals. After final identification of isolates, antibiotic susceptibility tests were carried out by using disk diffusion in agar method for 16 antibiotics and ESBL production was determined by the combined disk method. The Klebsiella pneumoniae strains showed susceptibility to imipenem and amikacin (94.3%), chloramphenicol (88.5%), gentamicin (81.1%), ciprofloxacin (80.3%), cefepime (73%), streptomycin (72.1%), nalidixic acid (68%), tetracycline (65.6%), and cefotaxime, ceftazidime, cefpodoxime (62.3%). The resistance of strains was seen to nitrofurantoin (53.3%), cotrimoxazole (39.3%), Cefpodoxime (37.7%), cefotaxime (36.9%), ceftriaxone (36.1%), aztreonam (34.4%), ceftazidime (32.8%). Thirty-eight isolates (31.1%) were shown to produce ESBLs. A high rate of resistance was observed to most of the antibiotics among ESBL producing strains; therefore, it is important to be careful about the use of antibiotics and identification of ESBL using phenotypic methods.

The periodic evaluation of antimicrobial activity of different antibiotic is essential because antibiotic sensitivity pattern may also changed during short courses. The aim of this study was to assess the frequency of Multi-drug Resistance (MDR) in Gram negative uropathogens. This study was conducted on 111 gram negative uropathogens using standard microbiology methods in Gorgan, 2011-2012. Antibiotic susceptibility was investigated by Kirby-Bauer disk diffusion methods (DDM). the most common isolates were klebsiella (40.5%), Enterobacter (26.1%), pseudomonas (13.5%), proteus(6.3%), acinetobacter (1.8%) and other gram negative bacteria (18.3%). The highest antibiotic resistance was seen to clindamycin (99.1%), and the most sensitivity to Carbapenems (94.6%).Multi drug resistant was seen in 68.5% of isolates. In inpatients, all of the citrobacter species had resistant to multi drugs simultaneously. a high frequency of multi drug resistant in uropathogens is observed in both inpatients and outpatients.