Increase in the prevalence of Panton–Valentine leukocidin and clonal shift in community-onset methicillin-resistant Staphylococcus aureus causing skin and soft-tissue infections in the Rhine-Neckar Region,Germany, 2012–2016

Methicillin-resistant Staphylococcus aureus (MRSA) remains a major challenge for patient care. Community-associated (CA)-MRSA often have a fitness and virulence advantage compared with their nosocomial counterparts. Increased mobility, travel activities and migration accelerate the intercontinental spread of virulent CA-MRSA strains. Outpatient clinics are the most important route of entry for CA-MRSA into hospitals. However, systematic data on CA-MRSA in Germany are limited. In this study, community-onset (CO)-MRSA skin and soft-tissue infection (SSTI) isolates in the Rhine-Neckar Region from 2012–2016 were characterised to gain an insight into their molecular epidemiology and to monitor potential introduction of virulent and dominant MRSA strains into our hospital. A total of 2475 patients with S. aureus SSTI were identified in the outpatient departments of our hospital, of which 94 (3.8%) were MRSA. In addition, 40.4% of the CO-MRSA harboured the virulence factor Panton–Valentine leukocidin (PVL). ST8-t008-MRSA-IVa/c (23.7%; 9/39) and ST80-t044-MRSA-IVc (15.8%; 6/38) were the predominant PVL-positive MRSA. Molecular typing and epidemiological data revealed that 42.6% (40/94) of strains could be traced back to a local origin and 44.7% (42/94) were endemic outside of Europe. Resistance to quinolones, clindamycin and macrolides was common, whilst resistance to trimethoprim/sulfamethoxazole, tetracycline, mupirocin, chlorhexidine and fusidic acid was low. No resistance to rifampicin, fosfomycin or linezolid was observed. This study provides insight into the clonal composition of CO-MRSA in the Rhine-Neckar Region. The increase of PVL-positive MRSA and the introduction of imported strains may affect the local MRSA landscape in the near future and should be monitored closely.     

Influenza-associated bacterial pathogens in patients with 2009 influenza A (H1N1) infection: impact of community-associated methicillin-resistant Staphylococcus aureus in Queensland, Australia

Background: Secondary bacterial pneumonia due to community onset methicillin‐resistant Staphylococcus aureus (MRSA) has become a highly publicised cause of influenza‐associated death. There is a risk that case reports of fatal outcomes with post‐influenza MRSA pneumonia may unduly influence antibiotic prescribing. Aims: The aim of this study was to demonstrate the incidence of community‐onset MRSA pneumonia in 2009 H1N1 influenza patients. Methods: The microbiology records of patients positive for influenza A (H1N1) in 2009 were reviewed for positive blood or respiratory tract cultures and urinary pneumococcal antigen results within a Queensland database. Patients with such positive results within 48 h of hospital admission and a positive H1N1 influenza result in the prior 6 weeks were included. Results: In 2009, 4491 laboratory‐confirmed pandemic influenza A (H1N1) infections were detected. Fifty patients (1.1% of the H1N1 cohort) who were hospitalised with H1N1 and who had a bacterial respiratory tract pathogen were identified. Streptococcus pneumoniae (16 patients; 32%), Staphylococcus aureus (13 patients; 26%) and Haemophilus influenzae (9 patients; 18%) were the most commonly cultured organisms. Of the cohort of 4491 patients, MRSA was detected in only two patients, both of whom were admitted to intensive care units and survived after prolonged admissions. Conclusions: Influenza‐associated community‐onset MRSA pneumonia was infrequently identified in the 2009 H1N1 season in Queensland, despite community‐onset MRSA skin and soft tissue infections being very common. Although post‐influenza MRSA pneumonia is of great concern, its influence on empiric‐prescribing guidelines should take into account its incidence relative to other secondary bacterial pathogens.     

Silver oxide‐containing hydroxyapatite coating has in vivo antibacterial activity in the rat tibia

Bacterial infection is a serious postoperative complication of joint replacement. To prevent infections related to implantation, we have developed a novel antibacterial coating with Ag‐containing hydroxyapatite (Ag‐HA). In the present study, we examined the antibacterial activity of Ag‐HA implant coatings in the medullary cavity of rat tibiae. Forty 10‐week‐old rats received implantation of Ag‐HA‐ or HA‐coated titanium rods, then were inoculated with ～1.0 × 10² colony‐forming units of methicillin‐resistant Staphylococcus aureus. Bacterial counts were calculated for rats euthanized at 24, 48, and 72 h postoperatively. Serum levels of Ag (in the Ag‐HA group only) were calculated for rats euthanized at 24, 48, 72 h and 4 weeks. Radiographic evaluations of bone infection were also performed at 4 weeks. Tibiae from both groups showing infection were evaluated histologically. Significant differences in bacterial counts were seen at 24, 48, and 72 h. Mean concentrations of Ag in serum peaked about 48 h after implantation, then gradually decreased. Mean radiographic scores for infection were significantly lower with Ag‐HA implants than with HA implants. Histological examination showed better results for abscesses, bone resorption, and destruction of cortical bone around Ag‐HA‐coated implants. These results indicate that Ag‐HA coatings may help prevent surgical‐site infections associated with joint replacement. © 2013 Orthopaedic Research Society Published by Wiley Periodicals, Inc. J Orthop Res 31:1195–1200, 2013     

Staphylococcus aureus bacteremia after thermal injury: The clinical impact of methicillin resistance

Objective

To evaluate the impact of methicillin resistance in Staphylococcus aureus bacteremia (SAB) on mortality and length of stay in burn patients.

Design

Retrospective cohort study.

Setting

A 750-bed tertiary care university hospital in Cologne, Germany.

Patients

Patients registered in the database of the burn intensive care unit (BICU) between 1989 and 2009 with complete data sets (n = 1688).

Results

Over the 21-year study period, 74 patients with SAB were identified; 33 patients had methicillin-resistant S. aureus (MRSA) and 41 methicillin-susceptible S. aureus (MSSA). Comparing the MRSA with the MSSA population the following parameters were significantly different in the univariate analysis: BMI (27.2 kg/m² vs. 23.6 kg/m²; P = 0.05), extent of deep partial thickness burns (17.8% vs. 9.0% of total body surface area; P = 0.007), antibiotic requirement on admission (45.5% vs. 22.0%; P = 0.046), median length of hospitalization prior SAB (24 days vs. 7 days; P < 0.001), packed red blood cells administration (47.6 units vs. 26.1 units; P = 0.003), intubation requirement (100% vs. 80.5%; P = 0.007), intubation period (43.5 days vs. 26.8 days; P = 0.008), catecholamine requirement (90.9% vs. 61.0%; P = 0.004), sepsis (60.6% vs. 34.1%; P = 0.035) and organ failures (81.8% vs. 39.0%; P < 0.001). Regarding outcome parameters, methicillin resistance was not significantly related with mortality (adjusted OR 1.55, 95% CI 0.56–4.28; P = 0.40) and length of BICU stay after SAB (Kaplan–Meier analysis log-rank test P = 0.32; Cox's proportional hazards regression HR 1.22, 95% CI 0.65–2.27, P = 0.535) in the univariate and multivariate analyses.

Conclusion

Our data suggest that methicillin resistance is not associated with significant increases in mortality and length of BICU stay among burn patients with SAB.     

qPCR快速检测金黄色葡萄球菌及MRSA方法的建立及评价

目的建立q PCR法快速检测金黄色葡萄球菌及其mec A基因,以期快速精准诊断金黄色葡萄球菌感染及初步判断耐药情况。方法从NCBI数据库下载金黄色葡萄球菌nuc、atl、ica B、fnb A、hla、srap基因序列用于鉴定标志筛选,mec A基因序列用于MRSA标志筛选;经DNA MAN比对后,选择各基因保守区分别设计1~2套引物、探针,建立单重及双重q PCR,用临床分离株及标准菌株筛选出检测性能最好的基因片段作为检测标志物,建立金黄色葡萄球菌鉴定和耐药双重q PCR检测方法,并进行性能评价。结果经筛选,金黄色葡萄球菌atl基因(CP009361.1:1010217~1010341)、mec A基因(KF058908.1:1715~1843)两片段检测性能最优,将其作为标志物建立双重q PCR法。该方法的检测下限均低至4 copies/反应;扩增线性范围均达2.0×102~8copies/m L。335份金黄色葡萄球菌(含94份MRSA)培养阳性的患者样本中,q PCR法分别检出SA 335份,MRSA 94份;95份金黄色葡萄球菌培养阴性的患者样本中,q PCR法分别检出SA 17份,MRSA 4份,经PCR产物测序,与标准菌株同源性均≥90%。双重q PCR法从样品处理到报告结果≤2.0 h。结论 q PCR法方法简便、快速、灵敏度高、特异性好,可望提高金黄色葡萄球菌感染的诊断能力并实现快速检测,为尽早精准治疗赢得时间。