Microbiology insights最新文献

Background: Sickle cell disease (SCD) patients are an important risk group for Staphylococcus aureus (S. aureus) carriage and infections. Little is, however, known about the nasopharyngeal carriage epidemiology of the pathogen in this vulnerable population.

Aim: The aim of this study was to evaluate S. aureus and methicillin-resistant S. aureus (MRSA) nasopharyngeal carriage prevalence, carriage determinants, and antimicrobial resistance among SCD adults in Ghana.

Methodology: Nasopharyngeal swabs, obtained from 200 SCD adults recruited at the Korle Bu Teaching Hospital, were cultured for S. aureus, and these isolates were subjected to antimicrobial susceptibility testing via the Kirby-Bauer method.

Results: The prevalence of S. aureus carriage was 41.5% (n = 83), and that of MRSA carriage was 1.0% (n = 2). Moreover, carriage of coagulase-negative Staphylococcus (CoNS) was the only determinant of S. aureus carriage identified (OR = 0.012, P < .0001). However, neither this variable nor the other features of the participants emerged as a determinant of MRSA carriage. The antimicrobial resistance rates decreased across penicillin (98.8%, n = 82), tetracycline (54.2%, n = 45), gentamicin (32.5%, n = 27), ciprofloxacin (21.7%, n = 18), erythromycin (18.1%, n = 15), clindamycin (10.8%, n = 9), amoxicillin-clavulanic acid (10.8%, n = 9), teicoplanin (1.2%, n = 1), and linezolid (0.0%, n = 0), and the multidrug resistance rate was 45.8% (n = 38).

Conclusion: The nasopharyngeal carriage prevalence of S. aureus in the current study was high, while that of MRSA was low. The isolates were highly resistant to several of the antibiotics tested, but not teicoplanin and linezolid, making these antibiotics suitable for treatment of S. aureus infections among the SCD population.

A serious concern of public-health proportion is rising from the carriage of antibiotic resistance determinant in Non-Lactose-Fermenting Bacteria and acquisition of virulence particularly in strains that are not routinely isolated or screened from common food animals. This study investigated the resistance profile and pathogenicity potential of selected Non-Lactose-Fermenting Bacteria isolated from 18 poultry farms. In total, we investigated the antibiotic susceptibility patterns of 25 Pseudomonas lactis and 71 Pseudomonas paralactis isolated from chicken faeces by testing them against 12 antibiotics. Resistance genes borne by the selected isolates were screened by sequencing the genetic location of resistance determinants was determined by plasmid curing. The virulence potential of the studied strains was determined phenotypically. Pseudomonas lactis isolates were mostly resistant to azetronam (93%), followed by trimethoprim (90%), cefotaxime (86%) and then amoxicillin/clavulanic acid (57%), while Pseudomonas paralactis. isolates were most resistant to azetronam (94%), trimethoprim (90%), cefepime (80%), piperacillin (75%) and amoxicillin/clavulanic acid (70%). The Multiple Antibiotic Resistance Index of Pseudomonas lactis and Pseudomonas paralactis isolates respectively ranged from 0.0 to 0.8 and 0.0 to 0.9. Polymerase Chain Reaction revealed the presence of antibiotic resistance factors such as blaCTX-M, qnrS, aac (6')-lb-cr and blaSHV while plasmid curing revealed carriages of resistance determinants on Resistance Plasmid. Moreover, virulence enzymes such as alkaline protease and phospholipase C were found in 3% and 12% of Pseudomonas paralactis and Pseudomonas lactis, respectively. This study reports the first occurrence of Pseudomonas lactis and Pseudomonas paralactis strains from chicken faeces, and their antimicrobial resistance and relative virulence suggest the encroachment of food animals by the under-studied non-lactose-fermenting bacteria that should alert public health concerns.

Coriaria myrtifolia occurs as natural flora of warm temperate climates of northern Algeria which commonly found in hedges, forest and ravine edges. This actinorhizal species was known to establish a mutualistic symbiosis with members of phylogenetic cluster 2 (including strains associated to Coriaria spp., Ceanothus, Datiscaceae, and Dryadoideae) within the genus Frankia. Attempts to isolate C. myrtifolia microsymbionts from native plants growing in 4 locations in Algeria permitted to only recover asymbiotic Frankia strains (unable to reestablish nodulation and to fix nitrogen) from phylogenetic cluster 4 and several non-Frankia actinobacteria including members of Micrococcus, Micromonospora, Nocardia, Plantactinospora, and Streptomyces genera. The biodiversity of Frankia microsymbionts of C. myrtifolia root nodules was assessed using PCR-amplification followed by partial nucleotide sequencing of glnA1 (glutamine synthetase type 1) gene. On the 12 different glnA1 gene sequences obtained in this study, 9 were detected for the first time, and were mainly closelyrelated to Mediterranean genotypes previously described in the Grand Maghreb countries (Morocco and Tunisia) and in Europe (France) but without clear separations from other cluster 2 genotypes.

Background: The purpose of this study was to compare different invasive methods for Helicobacter pylori (H. pylori) detection, namely PCR for H. pylori specific ureC gene, Rapid urease test (RUT), and histopathological examination by modified Giemsa staining.

Methodology: Endoscopic gastroduodenal biopsy materials were collected from dyspeptic patients who underwent endoscopic examination upon fulfilling the inclusion criteria. Three to four samples were collected from each patient after taking informed consent and proper clinical history. A rapid urease test (RUT) was done on spot with in-house RUT media from 1 specimen. One to two specimens were preserved in 10% formaldehyde for histopathology and PCR for ureC gene was done from 1 specimen. Collected biopsy specimens from gastric and duodenal mucosa of 142 patients were categorized as H. pylori-positive cases and H. pylori-negative cases based on the case definition used in the study upon positivity of 3 diagnostic tests.

Results: Among 142 biopsy specimens, 34.5% were categorized as H. pylori-positive cases, 35.2% as H. pylori-negative cases, and finally 30.2% as doubtful or indeterminate cases. Rapid urease test was the most sensitive method, closely followed by ureC gene PCR and histopathology, with a sensitivity of 94.2%, 83.0%, and 76.5%, respectively. Whereas histology was the most specific, having 98.0% specificity followed by 83.0% in PCR. RUT was the least specific, with 55.5% specificity.

Conclusion: While histopathology could detect H. pylori infection with the highest specificity, for definitive diagnosis combination of any 2 methods should be used, if available.

Various members of the enteric bacteria in recent times are evolving diverse survival mechanisms for antibiotic therapy resulting in failure of treatment in infection and disease cases. The Enterococcus species are potential strains implicated in gastrointestinal tract infection and are recently evolving in the resistance mechanism. The study evaluates the occurrence of New Delhi Metallo-beta-lactamase 1 (NDM-1) amongst Enterococcus species using the phenotypic and genomic characterization of environmental strains in the Oghara water nexus. Presumptive isolates of Enterococcus species were retrieved from various sampled water sources and confirmed using polymerase chain reaction (PCR). Antibiotic susceptibility testing was conducted on confirmed isolates using Kirby-Bauer disk diffusion methods. The result reveals 63 genus isolates confirmed Enterococcus species, of which 42 (67%) were Enterococcus faecium, 15 (23%) were Enterococcus faecalis, and 6 (10%) were other Enterococcus species. Fourteen among the E. faecalis isolates show resistance to Ertapenem-EDTA, while 17 (44.8%) of the E. faecium show resistance to Ertapenem-EDTA to presumptively reveal their NDM-1 phenotype. The PCR detection of the NDM-1 gene further confirmed 23 (36.5%) isolates as positive genotypes amongst the isolates that previously showed presumptive NDM-1 phenotype. It was also observed that 10 (15.9%) of Enterococcus faecium members harbored the NDM-1 genotype, whereas 8 (12.7%) members of the Enterococcus faecalis harbored the NDM-1 genotype. The observation of such resistance determinants necessitates a call for the adroit application of relevant therapeutics in the management of related infections and an environmental health caution to prevent the spread of such resistance potential enteric bacteria pathogens.

Background: Antimicrobial resistance (AMR) remains a global health challenge, as bacteria display increasing resistance to last-resort antibiotics such as carbapenems. Enterobacter cloacae are evolving and developing high level of resistance to carbapenems. With increasing AMR, availability of antibiotics for treatment dwindles, hence a need to complement antibiotics to enhance activity or reduce the level of resistance. This study explored the use of calcium ions in attenuating bacterial resistance to carbapenems.

Method: E. cloacae strains isolated from hospital fomites and air were subjected to antimicrobial susceptibility testing with carbapenem antibiotics (imipenem, meropenem, doripenem and ertapenem) using the disc diffusion (E. coli ATCC 25922 as control). Growth profile, Ca-Adjusted assay and time-kill curve of the strains was determined in the presence and absence of carbapenem antibiotics following a calcium stress assay.

Results: Growth profile showed that all the E. cloacae strains grew markedly well at 37°C relative to ATCC 25922 and all strains displayed 80% to 100% level of resistance to tested antibiotics. The growth rate of the strains in the presence of the antibiotics was comparable to the growth rate in the absence of carbapenems. Conditional growth stress with calcium ions showed a 50% reduction in the level of resistance with doripenem displaying the lowest level of reduction and ertapenem, the highest.

Discussion: The study showed that E. cloacae strains displayed high levels of resistance to carbapenems, increasing the possibility of treatment failure. Challenging strains with calcium prior to antibiotic treatment led to a significant reduction in level of resistance, indicating that calcium ions could affect bacterial strains during antibiotic activity leading to reduction in level of resistance.

Conclusion: Calcium supplement could potentiate carbapenem effectiveness and reduce bacterial AMR.

The renowned respiratory disease induced by the severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) has become a global epidemic in just less than a year by the first half of 2020. The subsequent efficient human-to-human transmission of this virus eventually affected millions of people worldwide. The most devastating thing is that the infection rate is continuously uprising and resulting in significant mortality especially among the older age population and those with health co-morbidities. This enveloped, positive-sense RNA virus is chiefly responsible for the infection of the upper respiratory system. The virulence of the SARS-CoV-2 is mostly regulated by its proteins such as entry to the host cell through fusion mechanism, fusion of infected cells with neighboring uninfected cells to spread virus, inhibition of host gene expression, cellular differentiation, apoptosis, mitochondrial biogenesis, etc. But very little is known about the protein structures and functionalities. Therefore, the main purpose of this study is to learn more about these proteins through bioinformatics approaches. In this study, ORF10, ORF7b, ORF7a, ORF6, membrane glycoprotein, and envelope protein have been selected from a Bangladeshi Corona-virus strain G039392 and a number of bioinformatics tools (MEGA-X-V10.1.7, PONDR, ProtScale, ProtParam, SCRIBER, NetSurfP v2.0, IntFOLD, UCSF Chimera, and PyMol) and strategies were implemented for multiple sequence alignment and phylogeny analysis with 9 different variants, predicting hydropathicity, amino acid compositions, protein-binding propensity, protein disorders, and 2D and 3D protein modeling. Selected proteins were characterized as highly flexible, structurally and electrostatically extremely stable, ordered, biologically active, hydrophobic, and closely related to proteins of different variants. This detailed information regarding the characterization and structure of proteins of SARS-CoV-2 Bangladeshi variant was performed for the first time ever to unveil the deep mechanism behind the virulence features. And this robust appraisal also paves the future way for molecular docking, vaccine development targeting these characterized proteins.

Background: Ready-to-eat foods are foods that are consumed at the point of sale or later, without any further processing or treatment. Foodborne diseases are on the rise worldwide, involving a wide range of diseases caused by pathogenic bacteria, and are becoming a public health problem. Therefore, this study sought to identify and determine the bacteriological quality and public health risks in ready-to-eat foods in developing countries.

Methods: The studies published from 2012 to 2020 were identified through systematic searches of various electronic databases such as Google Scholar, PubMed and MEDLINE, MedNar, EMBASE, CINAHL, Scopus, and Science Direct. The articles were searched using a Boolean logic operator ("AND," "OR," "NOT") combination with Medical Subject Headings (MeSH) terms and keywords. All identified keywords and an index term were checked in all included databases. In addition, a quality assessment is performed to determine the relevance of the article, and then the data are extracted and analyzed.

Results: The current study found that the pooled prevalence of Staphylococcus aureus, Enterobacter species, Klebsiella, Escherichia coli, Salmonella, Bacillus cereus, Pseudomonas species, and Shigella in ready-to-eat foods was 30.24% (95% CI: 18.8, 44.65), 11.3% (95% CI: 6.6, 18.7), 9.1% (95% CI: 7.0, 11.8), 23.8% (95% CI: 17.5, 31.5), 17.4% (95% CI: 11.6, 25.31)], 26.8% (95% CI: 13.7, 45.9), 6.1% (95% CI: 2.8, 12.6), 34.4% (95% CI: 18.1-55.4), respectively.

Conclusions: Most of the reviewed articles reported on various pathogenic bacterial species that are potentially harmful to human health, such as Staphylococcus aureus, Salmonella, Shigella, and Escherichia coli in ready-to-eat food above the maximum allowable limit. Therefore, relevant national and international organizations must take corrective measures to prevent foodborne diseases and protect human health.

Background: Intracranial abscesses have been a diagnostic and therapeutic challenge since time immemorial for both the microbiologists and the neurosurgeons. There is paucity of detailed studies documenting the infecting organism causing brain abscesses in South India.

Aims: The study aimed at identifying and assessing the prevalence of aerobic, anaerobic bacteria and fungi associated with brain abscesses at a tertiary care hospital in South India.

Methods and material: Eight years data was collected from the records of culture reports from 2007 to 2010 and 2013 to 2018. The corresponding clinical case records were retrieved for the assessment of risk factors. Risk factors of brain abscess development were assessed based on clinical cases records.

Results: Data from 140 brain abscess cases obtained over a period of 8 years were analyzed. Out of the 140 samples, 66 (47.14%) were culture positive in which 33 (50%) had single aerobic/facultative anaerobic bacteria, 20 (30.3%) had mixture of more than one aerobic/facultative anaerobic bacteria, 12 (18.18%) had single obligate anaerobic bacteria and 1(1.5%) sample had Mycobacterium tuberculosis isolated. Among the total 92 isolates, Pseudomonas aeruginosa (21/92, 23%) and Staphylococcus aureus (20/92, 22%) predominated. Bacteroides fragilis group was the most common obligate anaerobe isolated. There were no fungal isolates. As there were various isolates isolated, hence there is heterogeneity of isolates detected Neuroanatomically, parietal lobe (45/140, 32%) was the most common location. Otogenic infection was the major risk factor for parietal and temporal lobe abscess (P value < .05).

Conclusions: It has become essential for the microbiologists to be aware of unusual isolates from brain abscess and its complex nature. Obscurity and difficulty in their microbiological diagnosis calls for more such detailed studies.

The spread and transfer of resistant pathogens is on the increase worldwide and it is presently a cause of concern for health facilities, health organizations and governments. Pathogenicity is a factor dependent on the virulence of the microorganisms. The study aimed at determining the virulence markers and factors in multidrug resistant (MDR) Escherichia coli isolated from patients with urinary tract and gastrointestinal tract infections in Lafia, Nigeria. Collection of urine and stool samples (150 each) from patients was carried out, and bacteria isolated from the samples using the spread plate technique. Antibiotic susceptibility test was determined to identify resistant E. coli isolates after which, virulence factors and genes conferring virulence evaluated. The prevalence of E. coli was 33.3% and 35.3% in urine and stool respectively with 42 of the isolates being MDR. All the isolates showed cell surface hydrophobicity on ammonia sulfate molarity at >1.5, and all possessed capacity to produce hemolysin and pyrogen, though isolate U6 produced the highest amount of hemolysin and the other isolates mostly produced reasonable amount of pyrogen. Isolate U19 from urine sample and isolates S6, S10, S11, and S17 from stool samples all had between 81 and 100 serum resistance survival percentages, while 13 of the isolates had no serum resistance capabilities. Virulence conferring genes present in the isolates include fimH, pap, stb, cs31a, vt2, east1. Most of the resistant isolates have more than one virulence marker that is a means of producing an effective pathogenesis.