Infection Epidemiology and Microbiology
Year:2016 | Volume:2 | Issue:4|Papers Count:8

Background: Infections caused by Pseudomonas aeruginosa or Acinetobacter baumannii are of greatest concern for hospitalized patients, particularly those in intensive care units (ICUs). The aims of this study were to investigate the prevalence of integrons and biofilm formation among P. aeruginosa and A. baumannii isolates collected from ICU and non-ICU inpatients.Materials and Methods: A total of 90 P. aeruginosa and 90 A. baumannii isolates were recovered from patients admitted into diverse units of Shahid Mohammadi hospital in Bandar Abbas from January to December 2014. Bacterial identification was carried out by phenotypic methods and PCR. Antibiotic susceptibility was measured by disk diffusion assay. The presence of Class 1, 2, and 3 integrons were evaluated by multiplex-PCR. Biofilm quantification was done by microtiter method.Results: The highest number of isolates (48%) were recovered from ICU patients.81% of P. aeruginosa isolates were sensitive to piperacillin/tazobactam and ticarcillin, while 60% were resistant to third generation of cephalosporins. In case of A. baumannii, all the isolates were sensitive to colistin, but 98% were resistant to other antibiotics (p£0.05). Susceptibility to ceftazidime, ticarcillin, imipenem, and piperacillin/tazobactam were higher among isolates obtained from non-ICU patients. Class 1 integron was detected in 13.3% of the P.aeruginosa and 40% of the A. baumannii isolates, while Class 2 integron was harbored by 7 and 6.6% of the isolates, respectively.Furthermore, 23% of the A. baumannii and 12% of the P. aeruginosa isolates showed strong biofilm activity.Conclusion: Class 1 integron-positive isolates were resistant to three classes of antibiotics and predominantly observed in specimens collected from ICU patients showing strong biofilm.

Background: The importance of this research was to determine the prevalence of efflux pump genes among Acinetobacter baumannii isolates from hospitalized patients in Imam Reza hospital in Tabriz, Iran.Materials and Methods: This descriptive study was conducted in the Imam Reza hospital, Tabriz, IR Iran during June 2013 to March 2014. Twenty-six strains were isolated from female patients (42.6%) and thirty-five from male patients (57.4%). Clinical specimens were cultured for isolation of the microbial agents of A. baumannii. The isolated bacteria were identified using biochemical tests. Disk diffusion susceptibility test was used to determine the antimicrobial susceptibility, and E-test methods were also used. The prevalence of efflux pump genes was detected by PCR and sequencing methods.Results: The resistance of A. baumannii isolates against tested antibiotics was analyzed as follows: 51 (84%) to trimethoprim sulfamethoxazole, 59 (98%) to ceftazidime, 60 (99%) to ciprofloxacin, 29 (48%) to amikacin, 46 (77%) to gentamicin, 30 (50%) to tobramicin,, 60 (99%) to imipenem,, 60 (99%) to meropenem,, 60 (99%) to ceftriaxon,, 60 (99%) to cefepime,, 60 (99%) to ofloxacin, 6 (11%) to colistin. By using E-test, 45 (73.3%) to imipenem, 57 (93.3%) to ciprofloxacin, 23 (38%) to amikacin were also analyzed. The prevalence of adeA, adeB, adeC, and abeM genes was 54 (88.5%), 61 (100%), 57 (93.9%), and 60 (98.3%), respectively.Conclusion: The result of this study showed high incidence of AdeABC efflux pump in MDR A. baumannii isolates and the growing number of nosocomial infections associated with XDR A. baumannii complex, leading to difficulties in antibiotic therapy.

Background: Group B streptococcus (GBS) is the major cause of serious life threatening infections in neonates, pregnant women, and other adults with underlying diseases. Capsular polysaccharide typing is a significant way for epidemiological studies of GBS, the pathogenesis, and other studies associated with GBS infections including surveillance programs and vaccine development in future. Molecular serotyping (MS) methods offer more accurate and reliable typing of bacteria. The aim of current study was to differentiate genotypes of clinical GBS isolates based on PCR assay to acquire information about the distribution of GBS types in Hamadan, Iran.Materials and Methods: A total of 62 clinical GBS strains including vaginal swabs, urine cultures, and blood culture isolates were examined for genotyping using multiplex PCR assay.Results: Among the 62 GBS isolates examined, all capsular types, except VI, VII, and VIII, were found. Type III was the predominant type with 35 isolates (56.5%), followed by Type V with 11 isolates (17.7%), Type II with 7 isolates (11.3%), Type Ia with 5 isolates (8.1%), and Types Ib and IV with similar prevalence of 2 isolates (3.2%) for each type.Conclusion: The results of the current study demonstrated that Type III is the predominant type in Hamadan, followed by Types V, II, Ia, Ib, and IV, respectively. Using MS method leads to accurate, sensitive, specific, and fast typing of GBS isolates. The advantages of MS method allow it to analyze various populations and to examine invasive and colonizing isolates in extensive epidemiological studies and surveillance activities. In fact, MS will facilitate the proper formulation of candidate GBS vaccines.

Background: Streptococcus agalactiae, also known as Group B Streptococcus (GBS) is a commensal organism in the urogenital tract and rectum in approximately 25% of the healthy adult female population. The bacterium is the leading cause of bacterial meningitis, pneumonia, and sepsis in human infants.Materials and Methods: Our study was performed over a three - month period from April to June 2014. Midstream specimens of urine were collected from outpatients suspected of having a bacterial urinary tract infection, which had not received any antibiotics. Group B Streptococci isolates were confirmed by typical colony morphology and identified by differential tests. Antibiotic susceptibility testing was carried out by disk diffusion method on Mueller Hinton agar (Merck, Germany) based on (CLSI) Guidelines 2012.Results: GBS strains were isolated from 264 (21.1%) cases (out of 1249 positive bacterial urine cultures). The higher prevalence was recorded in the 15-44 and 45-64 age groups. Antibiotic susceptibility tests revealed that vancomycin, penicillin, and linezolid had the lowest, and tetracycline had the highest resistance rate.Conclusion: In conclusion, the results of the present study confirm the universal susceptibility of GBS strains to the penicillin family and assert the use of penicillin or ampicillin as the first drug of choice for treatment and prophylaxis against GBS infections. However, it is important to perform antibiotic susceptibility testing whenever penicillin could not be prescribed.

Background: Salmonella typhimurium is one of the most important species of Salmonella that is intracellular parasite and attacks host mucus membrane. These bacteria can cause gastroenteritis, and their main transmission route is water, poultry, meat, egg, and raw food. The aim of this study was to detect three virulence genes associated with S. typhimurium named invA, STM4497, and fliC183 genes by Multiplex PCR method.Materials and Methods: 183 samples of poultry were collected from food products in Zanjan (Iran) and cultured in BPW (Buffered Peptone Water) for 18 hr and at 37oC, and in RVS broth (Rappaport Vassiliadis Soya) for 6 hr at 41.5oC. After amplification of genomic DNA by Multiplex PCR method, occurrence of pathogen contamination was checked and compared with standard strain.Results: From the total of 183 collected samples, 52 (28.4%) samples were positive for S. typhimurium. The frequency of STM4497, fliC183, and invA genes were 49 (27%), 3 (2%), and 53 (29%), respectively.Conclusion: Simultaneous detection of invA, STM4497, and fliC183 genes were recognized as a key for detection of S. typhimurium by Multiplex PCR method.

Background: Hepatitis B infection is a major public health problem worldwide. Given that immune response towards the vaccine is not perfect, we aimed to evaluate circumstances of immune response in vaccinated students.Materials and Methods: In this study, 219 medical students of Ardabil University of Medical Sciences were recruited, who had been administered vaccine series for the first time, and booster doses after one and six months completely. The serum samples were extracted from whole blood of the participants. The concentration of Hepatitis B surface antigen (HBsAg) and anti-HBs antibody (HBsAb) was measured using a commercial ELISA kit.Results: It was observed that 201 cases (91.8%) out of 219 cases had positive anti-HBs antibody response, and 18 subjects (8.2%) were nonresponsive cases. Level of HBsAb was significantly different between males and females as well as alcoholics and non-alcoholics. None of the cases was identified as positive for HBsAg.Conclusion: Considering the results of the present and previous studies in other countries, it can be claimed that the mass vaccination has been effective, especially in medical students.

Most nosocomial infections have been attributed to nonfermenters, particularly Acinetobacter baumannii which causes serious infections like pneumonia, meningitis, and sepsis. The purpose of this study was to report our experience with five cases of A.baumannii-related pneumonia infections, seen in a regional hospital, Karaj, Iran. Five cases were identified as having A.baumannii- related pneumonia infection. All cases had been treated previously with various antibiotics at time of diagnosis. The treatment of A. baumannii- related pneumonia infection in all the cases varied. But unfortunately, all the five cases died from severe A. baumannii- related pneumonia and severe sepsis. Our cases brought forth the burden of A. baumannii-related pneumonia infections associated with significant mortality. Physicians should be aware of the remarkable virulence and antibiotic resistance.

Brucella is a facultative intracellular pathogen, and brucellosis is commonest zoonotic disease worldwide. Brucella species, isolated from domestic animals, are important pathogen for humans. Annually, more than 500, 000 new cases of brucellosis are reported, and this figure is an underestimate due to extended under-reporting cases in several endemic countries. Brucella has a variety of virulence mechanisms that prevent detection and activation of innate immunity, but protection against intracellular pathogen is represented by cell-mediated immunity. As yet, much research has been performed to develop a safe Brucella vaccine to control the disease in human and animals. Despite the availability of several live attenuated vaccine for animals, currently, no effective human vaccine is available. Moreover, due to the potential use of Brucella in bioterrorism or biowarfare, development of an effective vaccine against brucellosis for human use is necessary. In this paper, we aimed to review and discuss the efforts of researchers to develop vaccines against Brucellosis.