Inhibition of bacterial adhesion and anti-biofilm effects of Bacillus cereus and Serratia nematodiphila biosurfactants against Staphylococcus aureus and Pseudomonas aeruginosa

Background and Objectives

Biosurfactants are amphiphilic surface-active agents that mainly produced by various microorganisms. In this study, the anti-biofilm and inhibition of bacterial adhesion activities of two bacterial biosurfactants were investigated.

Materials and Methods

After extraction and evaluation of Bacillus cereus and Serratia nematodiphila biosurfctants, inhibition of bacterial adhesion and anti-biofilm effects of them on Staphylococcus aureus and Pseudomonas aeruginosa were determined.

Results

On average, the synergistic effect of two bacterial biosurfactants, caused about 60% decrease in adhesion and about 80% decrease in biofilm formation of S. aureus and P. aeruginosa.

Conclusion

The results of this study showed that combination of B. cereus and S. nematodiphila biosurfactants would increase the potential of attachment inhibition and biofilm eradication with very low toxicity.

Isolation of nontuberculous mycobacteria species from different water sources: a study of six hospitals in Tehran, Iran

Purpose

Nontuberculous mycobacteria (NTM) are ubiquitous bacteria that are naturally resistant to disinfectants and antibiotics and can colonize systems for supplying drinking water. Therefore, this study aimed to evaluate the prevalence of NTM in the drinking water of six hospitals in Tehran, Iran.

Methods

Totally, 198 water samples were collected. Each water sample was filtered via a membrane filter with a pore size of 0.45 µm and then decontaminated by 0.005% cetylpyridinium chloride. The membrane filters were incubated on two Lowenstein-Jensen media at 25 °C and 37 °C for 8 weeks. The positive cultures were identified with phenotypic tests, and then NTM species were detected according to the hsp65, rpoB, and 16S rDNA genes. Drug susceptibility testing (DST) was also carried out.

Results

Overall, 76 (40.4%) of the isolates were slowly growing mycobacteria (SGM) and 112 (59.6%) of the ones were rapidly growing mycobacteria (RGM). The most common NTM were Mycobacterium aurum, M. gordonae, M. phocaicum, M. mucogenicum, M. kansasii, M. simiae, M. gadium, M. lentiflavum, M. fortuitum, and M. porcinum. Among these 188 samples, NTM ranged from 1 to > 300 colony-forming unit (CFU) /500 mL, with a median of 182 CFU/500 mL. In the infectious department of all hospitals, the amount of CFU was higher than in other parts of the hospitals. The DST findings in this study indicated the diversity of resistance to different drugs. Among RGM, M. mucogenicum was the most susceptible isolate; however, M. fortuitum showed a different resistance pattern. Also, among SGM isolates, M. kansasii and M. simiae, the diversity of DST indicated.

Conclusions

The current study showed NTM strains could be an important component of hospital water supplies and a possible source of nosocomial infections according to the CFU reported in this study. The obtained findings also help clarify the dynamics of NTM variety and distribution in the water systems of hospitals in the research area.

Investigation into antibacterial and wound healing properties of platelets lysate against Acinetobacter baumannii and Klebsiella pneumoniae burn wound infections

Background and aim

Treatment of burn wound infections has become a global challenge due to the spread of multidrug-resistant bacteria; therefore, the development of new treatment options for the mentioned infections is essential. Platelets have drawn much attention for this purpose because they are a safe and cost-effective source of different antimicrobial peptides and growth factors. The present study evaluated antibacterial effects and wound healing properties of Platelet-derived Biomaterial (PdB) against Acinetobacter baumannii and Klebsiella pneumoniae burn wound infections.

Methods

PdB was prepared through the freezing and thawing process and then, in vitro antibacterial effect was determined by disk diffusion and broth microdilution methods. Afterward, burn wound was inflicted on 56 rats, infected with both bacteria, and topical administration was performed to evaluate antibacterial effects and wound healing properties of PdB.

Results

In vitro results showed that PdB inhibited the growth of A. baumannii in the highest dose (0.5), while we did not detect any inhibitory effects against K. pneumoniae. By contrast, PdB significantly inhibited the growth of bacteria in treated animal wounds compared to the control groups (P value < 0.05). Macroscopic assessments pointed to the significant enhancement of wound closure in the treated animals. In addition, histopathological examination demonstrated that treatment of rats with PdB led to a considerable increase in re-epithelialization and attenuated the formation of granulation tissue (P value < 0.05).

Conclusion

The use of topical PdB is an attractive strategy for treating A. baumannii and K. pneumoniae burn wound infections because it inhibits bacterial growth and promotes wound healing properties.

Smaller Copper Oxide Nanoparticles have More Biological Effects Versus Breast Cancer and Nosocomial Infections Bacteria

BACKGROUND AND OBJECTIVES

Despite promising successes in developing new drugs and pharmaceutical biotechnology, infectious diseases and cancer are still the principal causes of mortality and morbidity globally. Therefore, finding effective ways to deal with these pathogens and cancers is critical. Metal nanoparticles are one of the new strategies to combat bacteria and cancers.

METHODS

We examined the antimicrobial activity of 30 and 60 nm copper oxide nanoparticles (CuO-NPs) against Acinetobacter baumannii and Staphylococcus epidermidis bacteria responsible for nosocomial infections in standard and clinical strains and anti-cancer activity against 4T1 cell line as malignancy breast cancer cells. Synthesis of CuO-NPs was performed by a one-step reduction method and confirmed by DLS and TEM microscopy at 30 and 60 nm sizes. The antibacterial and anti-cancer activities of the nanoparticles were then investigated against the aforementioned bacteria and breast cancer.

RESULTS

Using disk, well, MIC, MBC methods, and viability/bacterial growth assay, 30 nm CuO NPs were found to have more antibacterial activity on standard and clinical strains than 60 nm CuO NPs. On the other hand, using MTT, apoptosis, and gene expression method, 30 nm nanoparticles were found to have more anti-cancer potential than 60 nm CuO NPs.

CONCLUSIONS

Our findings implicate CuO-NPs to possess antimicrobial and anti-cancer effects and more significant potential in smaller sizes, suggesting their pharmaceutical and biomedical capacity.
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Virulence determinants and biofilm formation of Acinetobacter baumannii isolated from hospitalized patients

Introduction

Acinetobacter baumannii are nosocomial bacteria that are responsible for outbreaks and severe infections in hospitalized patients globally. The major target of this study was the characterization of virulence determinants and biofilm formation of A. baumannii isolates from hospitalized patients.

Methods

In total, 100 A. baumannii were collected from three hospitals in Tehran, Iran, 2017-2018. The isolates were assessed using phenotypic and genotypic methods and then screened for virulence factor encoding genes such as plcN and lasB using conventional polymerase chain reaction. Furthermore, bacterial biofilm formation, motility and hemolytic and proteolytic activities were assessed.

Results

Of 100 A. baumannii isolates, 20 isolates included plcN and four isolates included lasB using PCR assay. Overall, 21 isolates were negative for biofilm formation while 45, 20 and 14 of the total isolates were reported as weak, moderate and strong biofilm producers, respectively. All isolates were positive for bap genes using PCR. Moreover, 35 isolates were motile on Luria-Bertani media, 47 isolates were α-hemolytic on Brucella blood agar media and all isolates displayed proteolytic activity.

Conclusions

Healthcare-associated infections with A. baumannii are a major concern, importantly due to their potency to acquire virulence factor genes. Therefore, shedding light in the discovery of new antimicrobial and/or therapeutic agents against virulent A. baumannii strains seem to be necessary.

The effect of Bacillus coagulans on cytotoxicity and apoptosis induced by Salmonella Typhimurium in HT-29 cell culture

BACKGROUND AND OBJECTIVES

Human epithelial cells have been widely used to study the interaction between intestinal cells and pathogens, in vitro. In this study, the effect of probiotic bacteria Bacillus coagulans and its supernatant on the growth inhibition, cytotoxicity and induction of apoptosis caused by Salmonella Typhimurium and its adhesion to HT-29 cells were investigated.

MATERIALS AND METHODS

B. coagulans supernatant was used to obtain the minimum inhibitory concentration. To evaluate the cytotoxicity and percent of apoptotic cells, B. coagulans and its supernatant (2, 4, 6 and 8% concentrations) with S. Typhimurium was added to HT-29 cells. The MTT assay was used in order to evaluate the cytotoxicity. Percent of apoptotic cells was reported using a fluorescence staining method. Additionally, the adhesion of S. Typhimurium to HT-29 cells was investigated. The effect of B. coagulans on the level of adhesion was also studied.

RESULTS

The most inhibitory effect was shown at the concentration of 80000 μg/ml supernatant of B. coagulans (54.77% ± 1.43). The simultaneous culture of S. Typhimurium with B. coagulans had the lowest amount of cytotoxicity and induced apoptosis among the all co-culture groups of S. Typhimurium with B. coagulans or its supernatant. The determined cytotoxicity and induced apoptosis were 26.06 % ± 3.79 and 17.63 % ± 2.14 respectively. In the adhesion test, it was observed that B. coagulans can significantly prevent adhesion of S. Typhimurium to HT-29 cell.

CONCLUSION

B. coagulans can reduce the adhesion, cytotoxicity and induction of apoptosis caused by S. Typhimurium in HT-29 cells in vitro.

RETRACTED ARTICLE: Silicotuberculosis as an occupational infection: rate, risk factors and control strategies

We, the Editor and Publishers of Archives of Environmental & Occupational Health, are retracting the following article:Abdolmajid Ghasemian, Farshad Nojoomi & Hassan Rajabi-Vardanjani, 'Silicotuberculosis as an occupational infection: rate, risk factors and control strategies,' Archives of Environmental & Occupational Health, 2019, DOI: 10.1080/19338244.2019.1619505We are now cognizant of a substantively similar version of this article that had previously been published in the journal New Microbes and New Infections.We have been informed in our decision-making by the guidance of COPE Guidelines on Retractions.The retracted article will remain online to maintain the scholarly record, but it will be digitally watermarked on each page as 'Retracted'.

The relation of phylogroups, serogroups, virulence factors and resistance pattern of Escherichia coli isolated from children with septicemia

The characterization of virulent and drug-resistant Escherichia coli strains helps to control and provide more accurate information regarding infection and eradication. The aim of this study was to determine the relationship between antibiotic susceptibility, phylogroups and virulence factors of E. coli isolates from children with septicaemia. One hundred dereplicated E. coli isolates were collected from paediatric patients with septicaemia in five hospitals in Tehran (May 2015 to May 2018). The antibiotic susceptibility of isolates was performed as per the 2016 guidelines of the Clinical and Laboratory Standards Institute. Extended-spectrum β-lactamases and carbapenemase genes, phylogroups, serogroups and virulence encoding genes were detected by PCR. Phylogroup B2 was dominant (40%) among strains, followed by phylogroups D (30%), A (8%) and B1 (7%). CTX-M1 was significantly higher in the B2 group (n = 21, p 0.001). Furthermore, the virulence genes iutA (n = 27, p 0.002), csgA (n = 39, p <0.001), kpsMII (n = 39, p 0.002), ibeA (n = 4, p 0.004), vat (n = 5, p 0.003), traT (n = 24, p <0.001), sat (n = 12, p 0.001) and hlyA (n = 33, p <0.001) showed significantly higher rates in phylogroup B2. Three O25/CTXM1/OXA-48 and cnf, iutA, csgA and traT positive isolates belonged to phylogroup B2. Pulsed-field gel electrophoresis analysis showed 85% similarity among 25% of isolates. More than half of the isolates were multidrug-resistant E. coli. A significant relation was observed among iutA, csgA, kpsMII, ibeA, vat, traT, sat and hlyA genes and phylogroup B2. The characterization of virulent and drug-resistant strains helps control and properly eliminate infections. There was no genetic relation among strains in the pulsed-field gel electrophoresis pattern.

Mycobacterium avium paratuberculosis and Mycobacterium avium complex and related subspecies as causative agents of zoonotic and occupational diseases

Mycobacterium avium complex (MAC) and Mycobacterium avium paratuberculosis (MAP) cause zoonotic infections transmitted by birds and livestock herds. These pathogens have remained as serious economic and health threats in most areas of the world. As zoonotic diseases, the risk of development of occupational disease and even death outcome necessitate implementation of control strategies to prevent its spread. Zoonotic MAP infections include Crohn's disease, inflammatory bowel disease, ulcerative colitis, sarcoidosis, diabetes mellitus, and immune-related diseases (such as Hashimoto's thyroiditis). Paratuberculosis has classified as type B epidemic zoonotic disease according to world health organization which is transmitted to human through consumption of dairy and meat products. In addition, MAC causes pulmonary manifestations and lymphadenitis in normal hosts and human immunodeficiency virus (HIV) progression (by serotypes 1, 4, and 8). Furthermore, other subspecies have caused respiratory abscesses, neck lymph nodes, and disseminated osteomyelitis in children and ulcers. However, the data over the occupational relatedness of these subspecies is rare. These agents can cause occupational infections in susceptible herd breeders. Several molecular methods have been recognized as proper strategies for tracking the infection. In this study, some zoonotic aspects, worldwide prevalence and control strategies regarding infections due to MAP and MAC and related subspecies has been reviewed.

Risk factors and control strategies for silicotuberculosis as an occupational disease

Silicotuberculosis is critical in community settings among workers and employees exposed to silica dust. Older age of entry (>30 years), male sex, infection with human immunodeficiency virus (HIV), exposure duration, smoking, chronic obstructive pulmonary disease, migration, the severity of the silicosis and the intensity of the exposure are potential risk factors. Lack of timely diagnosis and treatment for tuberculosis (TB) may also raise the rate of infection; previous treatment of TB is possibly associated with the development of silicotuberculosis in more than half of patients, increasing with age (>40 years). Identification of risk factors benefits not only the academic research community, but also the workers or employees and policy making. Some strategies can be implemented, such as controlling or reducing exposure to silica dust, ensuring continuity of treatment of TB or extended anti-TB treatment, management of the situation by occupational health professionals, prevention of oscillating migration, providing workers with compensation, training and education in occupational health, improving the quality of life of miners and workers, intensive medical surveillance and TB screening in routine health check ups, and policy making for higher immunity to inhibit inhalation of dust by workers or employees.

Prevalence of Clinically Isolated Metallo-beta-lactamase-producing Pseudomonas aeruginosa, Coding Genes, and Possible Risk Factors in Iran

BACKGROUND & OBJECTIVE

The spread of carbapenem-resistant Pseudomonas aeruginosa is a global concern. Metallo-beta-lactamase (MBL) enzymes cause extensive drug resistance among Gram-negative bacteria. The current study aimed at determining the prevalence of MBL-producing P. aeruginosa in Iran.

DATA EXTRACTION

A total of 43 studies were found out of which 36 were adopted. Data were collected from Google, Google Scholar, Science Direct, PubMed, Scopus, Embase, and Sciverse. The terms "Pseudomonasaeruginosa", "metallo-beta-lactamase", "prevalence", "carbapenems", and "Iran" were searched. Data from the isolates not producing MBLs were excluded from the study. Data were analyzed with Graph Pad Prism 6, meta-analysis section.

RESULTS

According to the results of the current study, 36 surveys indicated that 55% of the clinically isolated P. aeruginosa in Iran were resistant to imipenem and meropenem, among which 37.72% were the MBL producers. Among genes encoding MBLs, bla_VIM and bla_IMP were predominant with the prevalence of 12.91%±11.01% and 12.50%±23.56%, respectively. No report of harboring bla_NDM1 and bla_SPM1 by P. aeruginosa was found, similar to most of the other countries in Asia. The prevalence of bla_VIM and bla_IMP from burn settings were 11.50%±3.5% and 24.65%±23%, respectively. Furthermore, the prevalence of these genes was not significantly different among burn and non-burn isolates (P=0.942 and P=0.597, respectively). Moreover, no relationship was observed between the MBL production and patients' age range.

CONCLUSION

Approximately half of P. aeruginosa isolates were carbapenem-resistant in Iran, and approximately half were the MBL producers. The bla_VIM and bla_IMP were the predominant MBLs among P. aeruginosa strains, while other genes were not found in P. aeruginosa. Moreover, there was no significant difference between bla_VIM and bla_IMP among burn and non-burn isolates. Due to the multiple drug resistance conferred by MBLs, detection and control of their spread alongside proper therapeutic regimens in hospitals and community settings are essential to prevent infection acquisition.