Journal of medical microbiology最新文献

Introduction. The emergence of vancomycin-resistant Enterococcus faecium (VREfm) has left the vancomycin-sensitive E. faecium (VSEfm) strains almost unnoticed.Hypothesis. Molecular characteristics, hospital transmission patterns and clinical impact of VSEfm have changed, and VSEfm is a predictor of VREfm introduction.Aim. We wanted to do a molecular characterization of VSEfm to identify hospital transmissions and links between VSEfm and VREfm, and to investigate the demographics, treatment and impact on mortality of VSEfm bacteraemia.Methodology. VSEfm and VREfm blood culture isolates from Odense University Hospital, Denmark, from 2015 to 2019 were characterized using whole-genome sequencing and core-genome multilocus sequence typing (cgMLST). Clonal shifts and diversity of the VREfm isolates were compared to the VSEfm isolates. Hospital records were used for clinical data and transmission investigation of VSEfm cases.Results. Six-hundred and thirty VSEfm isolates from 599 patients belonged to 42 sequence types (STs) and 131 complex types (CTs) in several clusters. Multiple types were involved in putative transmission, occurring over the entire period. Twenty-seven VREfm bacteraemia cases were included. No correlation between the VSEfm and VREfm clones was identified. The 30 day mortality was 40 %, but only in 6.3 % of the cases, VSEfm bacteraemia was the likely cause of death.Conclusion. The molecular types of VSEfm bacteraemia isolates are changing and diverse. No direct correlation between VSEfm and the introduction of VREfm was found, but widespread hospital transmission indicates a presence of risk factors that could facilitate transmission of other micro-organisms as well. VSEfm bacteraemia is rarely the cause of death, indicating that 30 day mortality does not reflect the cause of death.

Introduction. Linezolid is an effective therapeutic option for treating severe infections caused by multidrug-resistant Gram-positive organisms. Several mechanisms have been reported to be responsible for resistance to this antibiotic.Hypothesis or Gap Statement. Although several mechanisms of linezolid resistance have been reported in Staphylococcus haemolyticus, the prevalence and potential for horizontal transfer of resistance genes have not been fully characterized, particularly among S. haemolyticus isolates from India.Aim. To perform whole-genome sequencing (WGS) of linezolid-resistant S. haemolyticus isolates to characterize the resistance mechanisms.Methodology. WGS was performed for 16 linezolid-resistant S. haemolyticus isolates to check for the presence of cfr, optrA and poxtA genes and mutations in 23S rRNA and ribosomal proteins (L3, L4 and L22) that are possible mechanisms implicated in linezolid resistance. Sequence types were identified using MLST finder. The minimum inhibitory concentration (MIC) of linezolid was determined using the E-test method. Polymerase chain reaction (PCR) was carried out for the detection of the cfr gene.Results. The study documented three different mechanisms of linezolid resistance in S. haemolyticus. Thirteen of the 16 isolates were phenotypically resistant to linezolid, of which 12 were positive for the cfr gene. The G2603T mutation in 23S rRNA was found in the majority of the isolates (n=13). Ten isolates had the R138V mutation in L3 ribosomal protein. Twelve isolates with the cfr gene in combination with either G2603T or R138V mutations displayed extremely high MIC values. Surprisingly, three phenotypically sensitive isolates were found to be positive for the cfr gene but negative for other resistance mechanisms. Importantly, in almost half of the isolates the cfr gene was present on a plasmid. ST3 and ST1 were found to be the predominant sequence types.Conclusion. All phenotypically resistant isolates exhibited two or three linezolid resistance mechanisms. The cfr gene was found on plasmids in many isolates, demonstrating its potential for horizontal transfer to more pathogenic organisms.

Swift and widespread deployment of an efficient malaria vaccine in Pakistan, together with basic control and preventive measures, could significantly decrease the economic and healthcare burden caused by drug-resistant malaria. Moreover, the RTS,S/AS01 vaccine has provided a much needed breakthrough after decades of growth, as an innovative vaccine for malaria in phase 3 clinical trials and currently undergoing implementation studies. Vaccination is a potentially critical component of efforts to arrest the development and dissemination of antimicrobial resistance, although little is known about the impact vaccination may have within low- and-middle-income countries.

Introduction. Antimicrobial resistance (AMR) to all antibiotic classes has been found in the pathogen Staphylococcus aureus. The reported prevalence of these resistances varies, driven by within-host AMR evolution at the patient level, and between-host transmission at the hospital level. Without dense longitudinal sampling, pragmatic analysis of AMR dynamics at multiple levels using routine surveillance data is essential to inform control measures.Gap Statement. The value and limitations of routinely collected hospital data to gain insight into AMR dynamics at the hospital and individual levels simultaneously are unclear.Methodology. We explored S. aureus AMR diversity in 70 000 isolates from a UK paediatric hospital between 2000-2021, using electronic datasets containing multiple routinely collected isolates per patient with phenotypic antibiograms and information on hospitalization and antibiotic consumption.Results. At the hospital level, the proportion of isolates that were meticillin-resistant (MRSA) increased between 2014-2020 from 25-50 %, before sharply decreasing to 30%, likely due to a change in inpatient demographics. Temporal trends in the proportion of isolates resistant to different antibiotics were often correlated in MRSA, but independent in meticillin-susceptible S. aureus. Ciprofloxacin resistance in MRSA decreased from 70-40 % of tested isolates between 2007-2020, likely linked to a national policy to reduce fluoroquinolone usage in 2007. At the patient level, we identified frequent AMR diversity, with 4 % of patients ever positive for S. aureus simultaneously carrying, at some point, multiple isolates with different resistances. We detected changes over time in AMR diversity in 3 % of patients ever positive for S. aureus. These changes equally represented gain and loss of resistance.Conclusion. Within this routinely collected dataset, we found that 65 % of changes in resistance within a patient's S. aureus population could not be explained by antibiotic exposure or between-patient transmission of bacteria, suggesting that within-host evolution via frequent gain and loss of AMR genes may be responsible for these changing AMR profiles. Our study highlights the value of exploring existing routine surveillance data to determine underlying mechanisms of AMR. These insights may substantially improve our understanding of the importance of antibiotic exposure variation, and the success of single S. aureus clones.

Background. Skin is a reservoir for millions of micro-organisms, all of which make up the skin microbiota. Hospitals have been identified as a favourable environment for transmitting micro-organisms and thus, it is important to know the distribution of skin microbiota among healthcare workers (HCWs), as such findings may provide baseline information for the distribution of skin microbiota in hospitals.Hypothesis. There is no significant association between the factors (age, gender, type of skin microenvironment, hand hygiene practices, usage of skin care products, current healthcare practices and previous workplace) and the distribution of the skin microbiota among HCWs.Aim. The study aims to identify type of skin microbiota and associated factors (age, gender, type of skin microenvironment, hand hygiene practices, use of skincare products, current healthcare practice, and previous workplace) that influence the growth of skin microbiota.Method. About 102 bacterial isolates were obtained from the skin of 63 healthcare workers in a newly opened teaching hospital, namely Hospital Pengajar Universiti Putra Malaysia (HPUPM). All isolated bacteria were subjected to phenotypic identification according to standard microbiological procedures.Results. The most common isolated skin microbiota were Gram-positive bacteria (84.3%), followed by Gram-negative bacteria (15.7%). A Chi-square test of independence was used to analyse the above factors and there was a significant association between the type of skin microenvironment and the distribution of skin microbiota (P=0.03) (type of skin microenvironment influences the distribution of skin microbiota).Conclusion. Coagulase-negative Staphylococcus spp. was the most common bacteria isolated from the skin of the healthcare workers. Even though coagulase-negative staphylococci (CoNS) are low pathogenic bacteria, but it may cause serious infection in high risk group of patients. Therefore, it is important to emphasize on the good hand hygiene practices and implement strict infection control measures to minimize the risk of HAI in newly opened hospitals.

West Nile virus (WNV) is a positive-sense single-stranded RNA virus belonging to the Flaviviridae family and is maintained in an enzootic cycle between avian hosts and mosquito vectors. Humans, horses and other mammals are susceptible to infection but are dead-end hosts due to a low viraemia. The disease can manifest itself in a variety of clinical signs and symptoms in people and horses from mild fever to severe encephalitis and morbidity. There are no vaccines licensed for human protection, but parts of Europe, North America, Africa and Australia have vaccines commercially available for horses.

Introduction. Serological screening and seroprevalence data for TORCH infections represent a key instrument to estimate immunity and vaccination levels and exposure rates to prevent and treat TORCH congenital infections.Hypothesis. Serology allows us to identify women susceptible to primary infection.Aim. Assess the prevalence of women at risk of primary infections by TORCH pathogens in Palermo, Sicily, Italy, in the decade 2012-2022.Methodology. A retrospective study was performed to evaluate the serological status (IgG and/or IgM) of 2359 women of childbearing age (WCBA), ranging from 16 to 46 years, attending the AOUP 'P. Giaccone' University Hospital of Palermo.Results. The results showed an overall prevalence of anti-TORCH IgG of 90.5 % for herpesvirus (HSV), 81.2 % for rubella virus (RV), 72.1 % for cytomegalovirus (CMV), 20.9 % for Toxoplasma gondii (TOX) and 4.8 % for Treponema pallidum (TP). IgM positivity was 16.9 % for HSV2, 10.3 % for TOX, 4 % for CMV and, 2 % for RV. A recent/active infection by TP was confirmed in 28.3 % of the seropositive women. Our results indicate that only a small percentage of WCBA were subjected to a comprehensive TORCH serological screening, while most WCBA were only tested for a single pathogen. In addition, no significant differences were found in terms of the overall TORCH IgG seroprevalence among different age groups (P>0.05).Conclusion. Identifying WCBA at risk of exposure during pregnancy allows us to prevent and reduce possible congenital infections, providing detailed guidelines and instructions. The results of this study showed that in Italy the risk of acquiring a primary infection by a TORCH agent is still high, therefore effective prevention strategies, including serological screening, should be implemented.

Introduction. Neutralizing antibodies have been widely used for the prophylaxis and treatment of COVID-19.Hypothesis. The major target for these neutralizing antibodies is the receptor-binding domain (RBD) of the viral spike protein.Aim. In the present study, we developed and characterized three neutralizing chimeric mouse-human mAbs for potential therapeutic purposes.Methodology. Light and heavy chain variable region genes of three mouse mAbs (m4E8, m3B6, and m1D1) were amplified and ligated to human Cγ1 and Cκ constant region genes by PCR. After cloning into a dual promoter mammalian expression vector, the final constructs were transiently expressed in DG-44 cells and the purified chimeric antibodies were characterized by ELISA and Western blotting. The neutralizing potency of the chimeric mAbs was determined by three different virus neutralization tests including sVNT, pVNT, and cVNT.Results. All three recombinant chimeric mAbs display human constant regions and are able to specifically bind to the RBD of SARS-CoV-2 with affinities comparable to the parental mAbs. Western blot analysis showed similar epitope specificity profiles for both the chimeric and the parental mouse mAbs. The results of virus neutralization tests (sVNT, pVNT, and cVNT) indicate that c4E8 had the most potent neutralizing activity with IC50 values of 1.772, 0.009, and 0.01 µg ml^-1, respectively. All chimeric and mouse mAbs displayed a similar pattern of reactivity with the spike protein of the SARS-CoV-2 variants of concern (VOC) tested, including alpha, delta, and wild-type.Conclusion. The chimeric mAbs displayed neutralizing potency similar to the parental mouse mAbs and are potentially valuable tools for disease control.