Journal of Medical Bacteriology
Volume:2 Issue: 1, 2013

Acinetobacter baumannii, is an important opportunistic pathogens responsible for nosocomial infections. The aim of this experiment was to determine prevalence of Class I Integron in A. baumannii strains isolated from burn patients in Mottahari Hospital and the drug susceptibility pattern. There were 69 Acinetobacter isolates, 68 (98.5%) were identified as A. baumannii. Antimicrobial susceptibility of these isolates were determined by a disk diffusion method. PCR assay for detection of blaOXA-51 like gene (for identity confirmation) and intI was performed. The most effective antibiotic for treating A. baumannii was colistin, followed by tetracyclin and tobramycin. The presence of Integron class I was detected in 14.49% of isolates. ESBL and carbapenemase production were observed in 10% and 24.6% of isolates, respectively. Due to the high resistance of strains lacking Integron I, the findings are although class I integrons are disseminated among clinical isolates of A. baumannii, at present research, they they do not play important role in dissemination of antibiotic resistance genes in Mottahari Hospital in Tehran, Iran.

In recent decades, extended spectrum beta-lactamase (ESBL) producing bacteria have increased worldwide. The most important causative agents of nosocomial infections throughout the world, Escherichia Coli and Klebsiella pneumonia as main ESBL-producing bacteria are so highly regarded. Trends in the treatment of infections by such bacteria have led to a global concern. This study was conducted to evaluate the incidence of ESBL producing E. coli and K. pneumonia among inpatients and outpatients referred to the Imam Reza hospital unit in Mashhad during 2007-8. This study represents a descriptive cross-sectional study. All 339 samples from hospital and a special clinic of the Imam Reza hospital of Mashhad were collected and cultured in defined media. Identification by morphological and biochemical tests were performed to determine the Enterobacteriaceae genera. The secretion of ESBL was studied by the double disc diffusion method. At the end, the data were analyzed by statistical software. Out of 339 isolates collected from 192 women (56.6%) and 147 men (43.4%), 26.5% of E. coli (n = 211) and 43% of K. pneumonia (n = 128) were ESBL positive. Most of the ESBL-positive isolates were related to ICU and the least of them were related to neonatal ward. The present study indicates the high prevalence of ESBL producing Enterobacteriaceae family especially in inpatients. Limiting the spread of such superbugs is of utmost importance.

The current study aimed to determine the effect and properties of surface-modified copper doped Cu:ZnO NPs on killing curves of bacterial pathogens. Preparation of in situ surface-modified copper doped ZnO nanoparticles (Cu:ZnO NPs) was done according to standard procedure.Assay for antimicrobial activity of Cu:ZnO NPs against bacterial pathogens was carried out based on disc diffusion method. Determination of shelf life, thermal and pH stability of antibacterial activity of Cu:ZnO NPs was done and residual activity was determined against the target cultures. FTIR spectra indicate that the nanomaterials synthesized have higher peak intensity compared with reagent grade ZnO. According to the SEM image the nanoparticles synthesized have different size and heterogeneous morphology. 400 ppm of Cu:ZnO NPs gave zones of inhibition with diameters of 9.0 – 16 mm against the target cultures. Amongst the target cultures, Escherchia coli was the most sensitive to the Cu:ZnO NPs inhibition zone diameter 16 mm; whereas, 9 mm wide inhibition zone was obtained against Staphylococcus aureus. The Cu:ZnO NPs was fairly stable for a period of 60 days at room temperature (RT) showing lost of only 20% and 30% antibacterial activity as tested against E. coli and S. aureus, respectively. The Cu:ZnO NPs was quite stable at this pH and temperature range tested against both E. coli and S. aureus. Surface-modified copper doped Cu:ZnO NPs have significant potential for their usefulness as antibacterial agents.

The pathologies classified as urinary tract infections (UTI) can have a deleterious effect on patients who have undergone a renal transplantation. Often recurrent UTIs will occur, leading to high morbidity, failure of the grafting process overall and even death. The study presented here seeks to expand the knowledge of recurrent UTIs in the context of renal transplantation, what risks recurrent UTIs pose to transplant patients and evaluate possible treatments. Renal transplantations were performed on 94 patients. For six months post-surgery the patients were evaluated for the presence of recurrent UTIs. The criteria for determining a patient as having a UTI was given as finding 103 pure colonies and 105 colonies within one ml of urine. The criteria of recurrent UTI was defined as two or more conclusive UTIs within the first six months after the surgery or three more within a year after renal transplantation. Of the 94 hospitalized patients, 29 UTIs were diagnosed (30.8%). The majority of diagnosed UTIs were in female patients (11.15, 73.3% vs. 4.15, 26.7%; p-value = 0.003). Those patients with diabetes mellitus correlated with a better chance of having a UTI (p-value = 0.019; CI = 1.2-12.2). The incidence rate of UTI was 51.7%, female predominant 73.3%. No other pathologies were shown to affect the chance of developing recurrent UTIs. Typically Escherichia coli was the bacterium isolated from urine cultures (48.3%) from those who developed recurrent UTI. The isolates tended to possess resistance to TMP / SMX and piperacillin but were susceptible to imipenem. Recurrent UTIs in renal transplant patients can be mitigated with proper identification of risk factors.

Legionella pneumophila is a dangerous pathogenic bacterium can cause serious infectious diseases especially in hospitalized immunocompromised patients. This bacteriumis shown to be resistant against different antibiotics. Resistance against a wide range of antibiotics is usually mediated by efflux pump in bacteria. Efflux pumps are proteinaceous transporters localized in the cytoplasmic membrane of all kinds of cells which excreted antibiotics outside the cells. However, synthesis of new anti-Legionella compounds or selection of resistant modulating agents are useful strategy to combat with L. pneumophilain the future. In this study the antibacterial activity of some benzofuranone derivatives have been investigated by disk diffusion method against L. pneumophila. Also the sensitivity of this test strain was evaluated against 40 antibiotics and the combination effect of reserpine at a sub-inhibitory concentration was further studied with these antibiotics using disk diffusion method with some modifications. Among the different synthetic compounds which were tested against L. pneumophila, the most antibacterial activity was observed for compounds 1j and 1m which contain hydroxyl and methoxy groups on the C-6 and C-7 positionsagainst L. pneumophila. To evaluate whether efflux pumps are active in L. pneumophila or not an efflux inhibitor (reserpine) was tested in combination of different antibiotics against this test strain. Reserpine significantly enhanced the antibacterial activities of kanamycin, nitrofurantoin, co-trimoxazole, erythromycin, ofloxacillin, gentamycin, rifampin, ciprofloxacin, nalidixic acid, minocycline, tobramycin, and amikacin against L. pneumophilawhich shows the resistances to these antibiotics are mediated by efflux system in this bacterium.

Brevinin-2R, as 25 amino acids peptide of the skin of Rana ridibunda frog, possesses potent antimicrobial and low hemolytic activity. It has an N-terminal hydrophilic region and a C-terminal loop that is delineated by an intra-disulfide bridge. In our study, Brevinin-2R and its diastereomer as well as its cyclic analogue were synthesized and characterized in order to investigate its structural features and biological implications. MIC determination is based on the recommended classical method of national comittee for labratory safety standard (NCLSS) and standard by Hancock With some change on cationic peptides. In this study All bacterial strains were obtained from Industrial-Scientific Research center. Both analogues showed lower antimicrobial activities compared to Brevinin-2R. In spite of Brevinin-2R peptide which shows low hemolytic activity, these analogues failed to show any hemolytic activity even at higher concentrations (up to 400 µg/ml). Based on proteolytic stability measurements, diastereomer and cyclic analogues displayed 90% and 60% residual antimicrobial activity, respectively, while antimicrobial activity of Brevinin-2R was 20%. The CD analysis revealed that amphipathic α-helical conformation of the synthesized peptides is involved in antimicrobial effects. CD studies and HPLC based measurement of retention time using a reverse phase column indicated that the Brevinin-2R can form an amphipathic loop resulting in an enhanced hydrophobicity. The hemolytic activity of Brevinin-2R and its analogues appeared to correlate with the retention time as well as the α-helicity. Accordingly, it seems that the combination of incorporating of D-amino acids into lytic peptides and their cyclization may result in developing new antimicrobial peptides with improved properties for treating infectious diseases.

Acute bacterial meningitis is among serious infections of the central nervous system (CNS). The early diagnosis and empiric antibiotic treatments have led to a reduction in morbidity and mortality rates. PCR and the enzymatic digestion of 16S rDNA fragment following the PCR by universal primers led up fast and sensitive determination. The aims of the present study was to improve our previous method for rapid and specific detection of common bacteria causing acute meningitis. According to the gene encoding 16S rDNA found in all bacteria, a set of primers was designed. Then the universal PCR was performed for bacterial agents of meningitis by employing broad-range DNA extraction method. The amplicons were digested with restriction enzymes to identify bacterial species. By the enzymatic digestion of the amplicons of each standard strain, specific patterns were achieved. These specific patterns may be used for comparison in CSF examination. The analytical sensitivity of the assay was approximately 1.5×102 CFU/ml of CSF even in samples with high amount of proteins. The universal PCR coupled with enzymatic digestion can be used to detect and identify bacterial pathogens in clinical specimens rapidly and accurately. Molecular diagnostic of bacterial meningitis, though expensive and labor-intensive, but is valuable and critical in patient management.

Despite impressive advancements in diagnostic and treatment technologies, infectious diseases still cause a significant amount of mortality and morbidity throughout the world due to the unpredictable and inevitable rise of new or previously dormant pathogens. Emerging infectious disease (EID) outbreaks are mainly associated with changes in physical environment and human behavioral activities, and disproportionately affect developing countries. Syndromic surveillance, while challenged in developing countries by inadequate communication and public health infrastructure, could build on pre-existing systems to complement existing governmental and non-governmental programs for outbreak detection and offers a promising avenue to detect EID events earlier in the course of an outbreak.