Staphylococcus hominis subspecies can be identified by SDS-PAGE or MALDI-TOF MS profiles

Rapid methicillin resistance detection and subspecies discrimination in Staphylococcus hominis clinical isolates by MALDI-TOF MS

PURPOSE

Staphylococcus hominis is a coagulase-negative opportunistic pathogen responsible for implanted medical device infections. Rapid identification and virulence factors detection are crucial for appropriate antimicrobial therapy. We aimed to search protein biomarker peaks for rapid classification of antibiotic resistance and subspecies of S. hominis using MALDI-TOF MS.

METHODS

S. hominis clinical isolates (n = 148) were screened for subspecies differentiation by novobiocin resistance. Biofilm composition and formation were determined by detachment assay and crystal violet staining, respectively. Antibiotic susceptibility was performed by the broth microdilution method. The search for potential biomarkers peaks was enabled by ClinProTools 3.0, flexAnalysis 3.4, and Biotools 3.2 for statistical analysis, peak visualization, and protein/peptide alignment, respectively.

RESULTS

Of 148 isolates, 12.16% were classified as S. hominis subsp. novobiosepticus, 77.77% were biofilm producers, and ˃ 50% were multidrug-resistant. Two potential biomarker peaks, 8975 m/z and 9035 m/z were detected for the discrimination of methicillin resistance with a sensitivity of 96.72%. The following peaks were detected for subspecies differentiation: 2582 m/z, 2823 m/z, and 2619 m/z with 88.89-98.28% of sensitivity.

CONCLUSIONS

We found potential biomarker peaks to predict methicillin resistance and discriminate S. hominis subspecies during routine MALDI-TOF MS identification in a clinical setting to enable better antibiotic treatment.

Laboratory Diagnostic Methods and Antibiotic Resistance Patterns of Staphylococcus aureus and Escherichia coli Strains: An Evolving Human Health Challenge

Raw ground meat is known as a transmission vehicle for biological agents that may be harmful to human health. The objective of the present study was to assess microbiological quality of the ground meats. A total of 280 samples of local and imported chilled meats were randomly collected from retail shops in Buraydah City, Saudi Arabia. The meat samples were microbiologically analyzed using standard methods, peptide mass fingerprinting (PMF) technique, MicroScan Walkaway System (MicroScan) and qPCR System. The imported meat was more bacterially contaminated than local meat, with variable contamination degrees of Staphylococcus aureus (40.33%), Escherichia coli (36.13%), Hafnia alvei (7.56%), Pseudomonas spp. (6.72%), Salmonella spp. (5.88%) and Aeromonas spp. (3.36%). PMF verified all the isolated bacteria by 100%, compared to 75-95% achieved by MicroScan. The gene encoding flagellin (fliC) was recognized in 67.44% of E. coli strains, while the thermonuclease (nuc) and methicillin resistance (mecA) genes were detected in 100% S. aureus and 39.6% of methicillin-resistant S. aureus (MRSA) strains, respectively. The S. aureus and E. coli strains were highly resistant to multiple antibiotics (e.g., ampicillin, amoxicillin-clavulanic acid and cephalothin). For identifying various foodborne pathogens, PMF has been recognized as a powerful and precise analytical method. In light of the increasing use of PMF to detect multidrug-resistant bacteria, this study emphasizes the need for improved ways of treating and preventing pathogens, as well as setting up monitoring systems to guarantee hygiene and safety in meat production.

Do Kinesio Tapes Increase the Skin Exposure to Pathogenic Bacteria?

BACKGROUND

Kinesio tapes (KTs) are tapes used in physical therapy and athletics. We sought to evaluate if wearing KTs for extended periods of time increases exposure to antibiotic resistant opportunistic pathogens and effects normal human skin bacteria.

METHODS

The study consisted of ten volunteers wearing nine KTs on their arms for five consecutive days. Microorganisms were isolated from fragments collected on the second and fifth day then analyzed. Bacteria were identified using the BIOLOG system. Resistance to selected antibiotics was performed using E-Test. The effect of KTs on the growth of Staphylococcus aureus, Staphylococcus epidermidis, and Micrococcus luteus was evaluated in a diffusion-based assay.

RESULTS

We found that KTs accumulated environmental bacteria. Among 22 species 8 were opportunistic pathogens, and all of them exhibited resistance to at least one antibiotic. None of the tapes produced inhibition zones in S. aureus. One tape, Leukotape P, caused growth inhibition in non-pathogenic S. epidermidis and M. luteus. The adhesive material of the tapes inhibited the growth of all bacteria.

CONCLUSIONS

These results indicate that KTs may increase the exposure to antibiotic resistant pathogens which can accumulate from the environment. Further, extended exposure could lead to changes in normal skin microbiota, potentially contributing to increased risks of skin infections.

Incidence, Prophylaxis and Prognosis of Acute Postoperative Endophthalmitis After Cataract Surgery: A Multicenter Retrospective Analysis in Northern China from 2013 to 2019

Objective

To investigate the incidence of acute postoperative endophthalmitis (POE) after cataract surgery in Northern China from 2013 to 2019, evaluate the efficacy of prophylaxis and analyze the predictors of visual prognosis among POE patients.

Methods

The study was conducted as a retrospective multi-center research, with seven hospitals in Northern China enrolled. The diagnosis of acute-onset POE was made on the basis of clinical manifestations within six weeks after initial surgery. By reviewing electronic medical system, the number of cataract surgeries and acute POE cases were recorded to estimate the overall incidence and incidences by different years and hospitals. Perioperative measures for preventing infection in different hospitals were collected. The correlations between unfavorable final vision and potential factors including basic information and clinical characteristics were examined to determine the predictive factors for final visual prognosis.

Results

Of 72,255 cataract surgeries performed during seven years in the seven hospitals, 19 cases developed acute POE, yielding an overall incidence of 0.026%. The average incidence of acute POE among seven hospitals significantly declined annually during the past 7 years (p = 0.021). In Hospital-D, the incidence of acute POE significantly decreased after the application of 0.5% povidone-iodine (PVP-I) for conjunctival washing (p = 0.003). Two hospitals adopting tobramycin in the irrigation solution achieved a significant lower incidence of POE than the other hospitals (p = 0.044). The positive rate of pathogen culture was just 17.6% (3/19). Patients with presenting BCVA of CF or better were more likely to present with unfavorable final vision than those with worse presenting BCVA (p = 0.003).

Conclusion

The overall incidence of acute POE after cataract surgery from 2013 to 2019 in Northern China was 0.026%, and the incidence declined annually over the period. Presenting BCVA could be a significant prognosis factor for predicting the final visual outcomes of acute POE patients.

Time to positive culture can differentiate post-neurosurgical coagulase-negative Staphylococci other than S epidermidis meningitis from contamination: A case-control observational study

Objective

To explore the characteristics of coagulase‐negative Staphylococci other than Staphylococci epidermidis (Nse‐CoNS) meningitis and to apply cerebrospinal fluid (CSF) times to positivity culture (TTPC) for the precise differentiation of meningitis from contamination.

Methods

We conducted a case‐control study to accomplish the following: First, we retrospectively reviewed records of post‐neurosurgical patients’ CSF that yielded Nse‐CoNS from January to October 2019 at the Beijing Tiantan Hospital; 17 clinical and 12 laboratory characteristics were reviewed. Second, we investigated the TTPC of the Nse‐CoNS, the cutoffs, and corresponding parameters to differentiate Nse‐CoNS meningitis from contamination.

Results

In this study, a total of 146 patients with Nse‐CoNS CSF culture positive were enrolled. The average TTPC in the Nse‐CoNS meningitis group was significantly shorter than in the contamination group (20.2 ± 5.0 hours and 30.2 ± 12.6 hours, respectively, P < .05). The area under curve (AUC) of the model was 0.802. A TTPC of 20.0 hours had 94.3% sensitivity and a negative value of 90.2% for predicting Nse‐CoNS meningitis.

Conclusions

Nse‐CoNS meningitis often causes confusion in clinical diagnosis. In this study, we evaluated the clinical predictive factors of Nse‐CoNS meningitis and confirmed that the median TTPC in the Nse‐CoNS meningitis group was significantly shorter than in the contamination group. A TTPC shorter than 20.0 hours was associated with Nse‐CoNS meningitis, while a TTPC longer than 20.0 hours was associated with Nse‐CoNS contamination. This information will be helpful for the rapid diagnosis of Nse‐CoNS meningitis.