Jundishapur Journal of Microbiology
Volume:11 Issue: 10, Oct 2018

  Pathogens surveillance and antimicrobial resistance are essential for the prompt organization of therapeutic and preventive actions in healthcare settings. We investigated the causative agents of intensive care unit (ICU)-acquired infections and their antimicrobial resistance in a university hospital over a nine-year period. An active, prospective surveillance was conducted in the ICUs of a tertiary care hospital between 2007 and 2015. The changing patterns in the frequency of pathogens and their antimicrobial resistance by the time were statistically evaluated with Mann-Whitney U test. A total of 3044 pathogens were isolated from 4272 healthcare-associated infections attacks in 3437 patients. The most frequently detected organisms were Acinetobacter spp. (n = 1060, 34.8%), Pseudomonas aeruginosa (n = 622, 20.4%), Escherichia coli (n = 340, 11.1%), Klebsiella pneumoniae (n = 331, 10.8%), and Candida spp. (n = 285, 9.3%). Carbapenem resistance among Acinetobacter spp., P. aeruginosa, E. coli, and K. pneumoniae was found as 82%, 30.7%, 2%, and 9.3%, respectively. The prevalence of extended-spectrum beta-lactamase (ESBL) among E. coli and K. pneumoniae was 49.7% and 41.3%, orderly, and methicillin resistance in Staphylococcus aureus was 81.8%. Substantial reductions occurred in the rates of E. coli (16.8% to 8.9%), S. aureus (11% to 3.2%), coagulase-negative staphylococci (7.9% to 0), and Stenotrophomonas maltophilia (4.2% to 0.3%) during the study period by the applied infection control measures while the rate of Acinetobacter spp. (9.7% to 51%) significantly increased. Furthermore, the increases in the carbapenem resistance among Acinetobacter spp. (52.5% to 91.4%), Pseudomonas spp. (25.7% to 51.6%), E. coli (0 to 12.7%), and K. pneumoniae (2.6% to 9%) and the decrease in the prevalence of ESBL-producing E. coli (57% to 27.2%) were statistically significant. Despite the decreases in the frequencies of staphylococci and some Gram-negative bacteria, the current infection control measures have been unable to limit the spread of carbapenem-resistant Gram-negative bacteria in our facility. Additional precautions are required to control such pathogens in the intensive care units

The outbreak of Zika virus (ZIKV) in many countries caused alarming numbers of babies born with microcephalus and severe neurologic disorders, however, the methods for the detection of the ZIKV are limited at present.

The aim of this study was to produce polyclonal antibody against full length envelop protein of ZIKV (ZIKV-E protein) in prokaryotic system and to evaluate its efficacy to capture ZIKV virion.

The recombinant full length ZIKV-E protein was purified and then used as an immunogen to vaccinate BALB/c mice to produce polyclonal antibody. Protein A/G coated magnetic beads were coated with the polyclonal antibody to capture the ZIKV virion in the culture medium of Vero cells infected with ZIKV. The products of immunoprecipitation were further used for Western Blot, Loop-mediated isothermal amplification (LAMP), and PCR assay.

Western Blot and indirect immunofluorescence analysis showed that the mouse polyclonal antibody could react specifically with the native E protein in Vero cells infected with ZIKV. The results of Western Blot, Immunocaptured-LAMP (IC-LAMP), and Immunocaptured-PCR (IC-PCR) showed that polyclonal antibody of ZIKV-E recombinant protein can capture ZIKV virion specifically, however, the polyclonal antibody against the ZIKV-NS1, Shigella, and Salmonella without such a function.

These findings may provide the basis for the development of the rapid diagnostic kits such as, IC-PCR, IC-LAMP, and sandwich ELISA. The serum virion capture activity elicited by prokaryotic expressed recombinant ZIKV-E protein may also provide a basis for further preparation of neutralizing antibody and protein subunit vaccine candidate against ZIKV

Streptococcus pneumoniae can adhere to lung cells via many adhesins, including pneumococcal serine-rich repeat protein (PsrP). Glycosyltransferase A (GtfA) and glycoslytransferase B (GtfB) were found to initiate PsrP glycosylation in Streptococcus pneumoniae serotype 4, isolate TIGR4.

To test whether GtfA and GtfB are conserved among S. pneumoniae isolates presenting with different serotypes and are involved in the glycosylation of PsrP via formation of the glycosyltransferase complex GtfA-GtfB.

Serotyping of S. pneumoniae was performed using polymerase chain reaction (PCR) assays. The evolutionary divergences of GtfA and GtfB among different isolates were estimated using MEGA4 software. The contribution of GtfA and GtfB to the glycosylation of PsrP was identified using an in vivo glycosylation system in Escherichia coli. Interaction of GtfA with GtfB was assessed using a glutathione S-transferase (GST) pull-down assay and yeast two-hybrid experiment.

Nine different S. pneumoniae serotypes were found, of which the most frequent was 19F. The pneumococcal isolate TIGR4 and 22 other clinical isolates were included to estimate evolutionary divergence. The average homologies of the GtfA and GtfB sequences were 99.59% and 98.53%, respectively. Glycosyltransferase A and GtfB were shown to be required for the transfer of N-acetylglucosamine moieties to PsrP1-374. Glutathione S-transferase pull-down assays and yeast two-hybrid experiments showed that GtfA directly interacted with GtfB.

Glycosyltransferase A and GtfB are conserved in S. pneumoniae isolates. Glycosyltransferase A interacts with GtfB, forming the glycosyltransferase complex GtfA-GtfB, which is required for PsrP glycosylation.

Over the last several years, Acinetobacter has emerged as a leading cause of hospital-acquired infections. Aminoglycosides are frequently used in the treatment of invasive infections. Factors associated with the resistance to aminoglycosides include the reduction of drug uptake, modification of aminoglycosides, and aminoglycoside efflux. The aim of our study was to phenotypically detect the presence of efflux mechanism using carbonyl cyanide 3-chlorophenylhydrazone (CCCP) in aminoglycoside resistant Acinetobacter baumannii strains isolated from different hospital wards. In total, 57 A. baumannii isolates were collected from two Egyptian hospitals. The antimicrobial susceptibility pattern was determined. The activity of the efflux system was evaluated using CCCP. Among 57 A. baumannii isolates, most resistance was observed against tobramycin, amikacin, kanamycin, neomycin, and gentamicin. The minimum inhibitory concentrations (MIC) range of A. baumannii was between 2 and 1024 µg/mL based on the tested antibiotics. The phenotypic detection of efflux pumps displaying a reduction of at least two folds in the MICs of antibiotics after addition of the efflux pump inhibitor showed that 19.4% of the isolates became less resistant to kanamycin, 44% to tobramycin, and 46% to amikacin but lower rates were recorded against gentamicin (12.2%) and neomycin (9.4 %). Our study suggests that the efflux mechanism is getting widespread in clinical settings to play an important role in aminoglycoside resistance. Acinetobacter baumannii has the ability to gain resistance to different antibiotic classes through these active efflux pumps. Hence, the application of strict infection control measures together with novel approaches to eradicate those efflux transporters should be applied in hospital settings.

Salmonella spp. is one of the most important zoonotic pathogens transmitting among human and animals. Due to the similarity of antibiotic classes used to treat animals and humans, there is a high risk for emerging the multi-drug resistant (MDR) strains.

The current study aimed at evaluating molecular detection, virulence genes, biofilm formation, and antibiotic resistance of Salmonella enterica serotype enteritidis recovered from poultry and clinical isolates.

A total of 282 isolates were recovered from chicken meat, live poultry feces, eggs, and human feces in Iran. The presence of virulent factors in the isolates was confirmed using biochemical and microbiological tests. The presence of Salmonella genus was determined using antiserum. Triplex polymerase chain reaction (PCR) was performed to detect Salmonella spp., serogroup D and the discriminate S. enteritidis from other species. Kirby-Bauer disk diffusion method was applied to perform the susceptibility testing. Quantification of biofilm formation was determined in 96-well microtiter plates as recommended by the defined protocol. The data were then analyzed with SPSS using consensus tables and Chi-square test.

Based on the results, all the isolates were positive for invA, sdiA, hilA, and ratA. Moreover, spvC had the lowest prevalence (37.6%). Of all strains, 67% were MDR, 51.7% of which were recovered from humans. Furthermore, 34.5% of isolates were strong biofilm producers. There was a significant correlation between the strong biofilm formation and the antibiotic resistance to colistin, ceftazidime, chloramphenicol, gentamicin, trimethoprim, penicillin, and trimethoprim-sulfamethoxazole.

The results of the current study showed a significant correlation between the strong biofilm formation and the antibiotic resistance to some antibiotics

 

The incidence of fungal infections caused by the yeasts and yeast-like species increased dramatically in immunocompromised patients, during the past several decades. However, a few of yeast and yeast-like species may colonize in skin and mucous membranes of healthy individuals.

The current study aimed at accurately identifying yeast and yeast-like species from clinical samples by molecular methods.

A total of 1200 clinical samples were collected from patients with suspected fungal infection and 110 (9.16 %) yeast and yeast-like strains isolated and identified by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP), PCR amplification of hwp1 gene, and sequencing.

In total, Candida albicans (n = 46) was the most frequently isolated species followed by C. parapsilosis complex (n = 17), C. tropicalis (n = 13), C. guilliermondii (n = 12), C. glabrata (n = 4), C. krusei and C. famata each (n = 3), C. kefyr, C. haemulonii and Cutaneotrichosporon jirovecii each (n = 2), and C. stellatoidea, C. intermedia, C. sorbosivorans, C. africana, Pichia kudriavzevii, and Trichosporon asahii each (n = 1). Interestingly, C. haemulonii, a multidrug resistant fungus was isolated from cutaneous and sputum samples for the first time in Iran.

Nowadays, with growing population at risk for fungal infections and the emergence of some less virulent or non-pathogenic and uncommon yeasts not readily distinguishable with phenotypic assays, the accurate identification using molecular methods are warranted

Drug resistance in Candida species, has emerged as a major problem in the public health system worldwide. Application of nanoparticles is proposed as a novel and potential agent for reduction of drug resistance burdens.

The current study was conducted to evaluate the effects of zinc oxide nanoparticles (ZnO NPs containing chitosan and linoleic acid) on hyphae cell wall proteins (Hwp1) gene expression, a crucial gene in pathogenicity of Candida albicans, and cytotoxicity on human hepatocyte carcinoma (HepG2) cells as well as the production of Reactive Oxygen Species (ROS).

The effects of novel ZnO NPs on expression of Hwp1 gene of C. albicans was analyzed using quantitative real-time polymerase chain reaction (qRT-PCR) in comparison to fluconazole as a standard drug. Reactive Oxygen species production was examined in macrophages treated with ZnO NPs relative to non-treated cells. Also, the cytotoxicity effects of ZnO NPs were assessed using the MTT assay against HepG2 cell line.

The findings indicated that ZnO NPs significantly decreased the level of Hwp1 gene expression in standard and clinical isolates of C. albicans. Increased level of ROS production in macrophages was found in the presence of ZnO NPs in concentration-dependent manner compared to the control group without exposure of ZnO NPs (P = 0.001). Furthermore, ZnO NPs did not show cytotoxicity activity on HepG2 cells at different concentrations (P > 0.05).

Taken together, the newly synthesized ZnO NPs may be a suitable candidate for inhibition of the critical gene responsible for biofilm dispersion and the control of Candida infection with limited cytotoxicity on human cells. However, more studies are required for support of its effect in vitro and in vivo

With the widespread use of antibiotics and increasing number of immunocompromised patients, many rare bacterial infections have become increasing. Recently, only a few cases showed central nervous system (CNS) nocardiosis and Exiguobacterium bacteremia. However, the case that CNS nocardiosis together with Exiguobacterium bacteremia has never been reported.

The patient was admitted to a tertiary hospital with CNS infection symptoms. Cerebrospinal fluid and blood were both sent to culture. Pathogens were both isolated from cerebrospinal fluid and blood, following 16s rRNA sequencing, which were finally identified as Nocardia and Exiguobacterium species.

It is the first reported case of CNS Nocardia terpenica infection in a patient without abscess formation in the CNS. Additionally, this patient also had a complex infection involving Exiguobacterium profundum bacteremia