دو ماهنامه میکروب شناسی پزشکی ایران
سال سیزدهم شماره 3 (امرداد و شهریور 1398)

Mycoplasma pneumoniae is one of the major species of mycoplasmas which could contaminate cell cultures. Identification of
M. pneuminae is significant because Mycoplasmas could contaminate and have unsuitable effect on the cell cultures. Rapid detection of these contaminations is so important and it could be significant role in preventing and controlling of contamination in cell cultures. The aim of this study is isolation and detection of
M .pneumoniae by culture and PCR. 82 cell cultures collected and cultured in PPLO broth media supplemented for M. pnemoniae isolation.

The bacteria DNAs were extracted by phenol/chloroform method and the PCR assay amplifying the conserved region of 16S rRNA gene was applied for the detection of Mycoplasma genus in 163bp fragment and M. pnemoniae in 543bp fragment by using of MPF and MPR primers which obtained from P1 adhesin gen.

Of the 82 samples 48(58.5%) yielded one of the potentially pathogenic Mycoplasmas evaluated for using Mycoplasma genus PCR as diagnostic method, and from 48 samples which were positive in genus of Mycoplasma, M. pneumoniae did not detect  from those sample by using those primers and there is not any M. pnemoniae detected in this study.

Also results of this study indicate that PCR could be an alternative method instead of the culture because according to the results of this study, PCR has high accuracy and speed for detecting M. pneumoniae.

The type IV Pilin is an important colonization factor for opportunistic pathogens of Pseudomonas aeruginosa, which plays a role in the formation of biofilms and binding to the host cells. Each type of Pilin is coded with a particular auxiliary gene. This specific relationship can be used as a therapeutic target for detecting P. aeruginosa strains as well as its molecular classification. The purpose of this study was to evaluate the frequency of different types of auxiliary genes in cystic fibrosis, burns, and environmental samples.

Pseudomonas aeruginosa samples were collected from patients with cystic fibrosis, burns as well as environmental wastewaters during 2016-2017. Samples were cultured and identified using standard microbial and biochemical methods. DNA extraction was performed by boiling and PCR was performed through specific primers.

Totally, 90 isolates of P. aeruginosa samples (35 environmental, 30 burns, and 25 cystic fibrosis) were examined. tfpO and tfpZ were positive in 71 and 2 isolates, respectively.

The results indicated that Pseudomonas aeruginosa Pilin types are very diverse. Regardless of the source of the samples, the most common tfp was tfpO. Taking into account the fact that tfpZ was found only in burns, it can be assumed that this particular type may appear in severe clinical conditions. Ultimately, larger statistical population and use of more comprehensive typing methods is suggested for better results.

Tuberculosis kills more than 1 million people every year, most of them in low-income and middle-income countries. An understanding of the trends in tuberculosis incidence, prevalence, and mortality s crucial to track the success of tuberculosis control programs. Microbiological diagnosis of diseases caused by Mycobacteria should be fast and effective to prevent contagions and optimize the management of infections.

A total of 1412 clinical pulmonary and extra pulmonary specimens were studied from January 2017 to December 2017 at Nizam's Institute of Medical Sciences, Hyderabad. All specimens were processed according to standard operating procedures. All the specimens were subjected to microscopy, culture, GeneXpert.

Among 1412 samples received 813 were males (57.6%) and 599 females (42.4%). Among these 818 (57.9%) were pulmonary samples and 594 extra pulmonary samples. Mycobacterium prevalence was (21.6%) out of which Mycobacterium tuberculosis was found in 18.3% and Non tuberculous Mycobacteria (3.25%). The contamination rate was 2.6% (37 out of 1412). Among the positives, the most common affected age group was 21-30 yrs (22.2%). About 64 (4.53%) were smear positive. A total of 200 isolates (14.16%) were recovered by at least one culture LJ medium or BacT Alert 3D system. MTB was recovered in 216 (15.29%) by GeneXpert. MDRTB was detected in 8 (3.7%) by GeneXpert.

M. tuberculosis complex is responsible for immense worldwide morbidity and mortality. Delays in diagnosis may postpone administration of appropriate treatment and be detrimental to patient outcomes. Since traditional culture methods are slow, newer molecular techniques allow more rapid and sensitive laboratory diagnosis of tuberculosis.

Nowadays due to the harmfulness of chemical preservatives, the use of natural preservatives has increased. Bacteriophages are bacterial mandatory parasites that are harmless for human and animals and can, therefore, be used as appropriate antimicrobial agents in food. The aim of this study was to isolate the Escherichia coli lytic phage from wastewater, identify and evaluate its efficiency in controlling E. coli infection in chicken meat.

E. coli (PTCC: 1330) was obtained from Iranian Science and Technology Research organization. Phage isolated from the wastewater of Malayer dairy factory and its antimicrobial effect was investigated through plaque formation. TEM microscopy was used to observe the phage morphology and to determine its possible family. Host spectrum against 6 E. coli strains and its effect? against Salmonella enterica, Staphylococcus aureus and Yersinia enterocolitica were also evaluated .The effect of E. coli lytic phage on the amount of inoculated E. coli to contaminate the chicken meat was examined.

The isolated phage was tailless and had round capsid, possibly belonging to the Tectiviridae family. The target phage had antimicrobial activity against 5 selected E. coli strains, unlike the other genera tested. The effect of the phage on the E. coli contamination in chicken meat showed that the bacterial count was reduced from 3 log10   to 1.8 log10 after 24 h and reached less than 1 log cycle after 4 days.

The isolated phage had strong antimicrobial effect against E. coli. Therefore, it can be a good preservative candidate for use in foods.

Flow cytometry is a rapid method that can analyze thousands of cells per second and can be used for determination of microbial populations and determination of bacterial antimicrobial susceptibility. In this study antibiotic resistance pattern of Acinetobacter baumannii isolates by flow cytometer was evaluated.

55 isolates of Acinetobacter baumannii were isolated from clinical specimen of patients and were identified by biochemical tests. Antibiotic resistance patterns were studied by disc diffusion method and MDR strains were selected. MIC of Meropenem and Piperacillin were determined. Also antibiotic resistance pattern of isolates was determined by coloring with Rhodamine-123 and flow cytometry.

98% of isolates were MDR. The MIC ranges for maropenem were 8 - 256 μg/mL and for piperacillin were 128-1024 μg/mL. By flow cytometry it was demonstrated that at concentrations of 8, 4 and 2 μg/mL of meropenem, only 1.96%, 1.44% and 0.59%, of cells were killed respectively. At concentrations of 64,128 and 16 μg/mL of piperacillin, 13.8%, 11.3% and 5.9%of cells were killed respectively. Reducing the number of living bacteria was observed with increasing concentrations of both antibiotics.

The similarity between the results of flow cytometry and both agar and broth antibacterial susceptibility methods showed flow cytometry as a reliable and rapid test that can be used  for this purpose.

Increasing drug resistance to antibiotics in most bacteria has led to the development of natural antimicrobial compounds. Peppermint (Mentha piperita L.) is one of the most widely used herbs that has many therapeutic effects. The purpose of this study is the evaluation of antimicrobial and antioxidant activity of essential oil of Mentha piperita L.

 In this study, after collecting and drying the leaves, essential oils of the plant was extracted using a solvent-free microwave extraction. The compounds of essential oil were identified by the GC-MS (Gas chromatography-mass spectrometry). The effect of antioxidant was determined by beta-carotene test and antimicrobial activity was carried using agar-dilution method also, the minimum inhibitory concentration (MIC) value was evaluated.

Menthol, Menthofuran, and 1S-Neomenthyl acetate were the major compounds of essential oil of Mentha piperita L. collected from Marivan, respectively; menthol is the main compound of essential oil. The essential oil was more effective on gram-positive bacteria (Staphylococcus epidermidis, Bacillus subtilis, Staphylococcus aureus) and gram negative (Shigella dysenteriae, Klebsiella pneumonia) also had a good antioxidant activity compared to the standard BHT (butylated hydroxytoluene).Due to its relatively good antimicrobial and antioxidant properties, it can be used in the pharmaceutical and food industries.

Methicillin-resistant Staphylococcus aureus strains are resistant to many antibiotics. One of the major causes of drug resistance in bacteria is the efflux pumps. Matricaria chamomilla is a plant that is effective in treating skin diseases. The aim of this study was to investigate the effect of M. chamomilla alcoholic extract on phenotype detection and inhibition of efflux pumps of methicillin resistant S. aureus (MRSA) isolated from skin lesions.

The study was performed on 30 strains of S. aureus isolates collected from skin infections. The Strains of MRSA were detected by cefoxitin disc diffusion test. M. chamomilla alcoholic extract was prepared and its MIC was obtained against MRSA strains by broth microdilution method. Cartwheel method was used to study phenotypic activity of efflux pump. The effect of M. chamomilla extract was investigated on strains with active efflux pumps.

from 30 strains of isolated S. aureus, 33.3% were methicillin-resistant. Three strains (10%) had active efflux pump, among which one strain was detected as MRSA. MIC of M. chamomilla extract was between 12-64 μg/ml. With the effect of ½ MIC of M. chamomilla extract on the strains with a strong efflux pumps, the two stains were reported as non-actives. M. chamomilla extract on the MRSA strain efflux pump was ineffective. Antimicrobial effect of M. chamomilla extract was confirmed on MRSA isolated from skin lesions.