Multiplex PCR for rapid detection of Staphylococcus aureus isolates suspected to represent community-acquired strains

Mandatory Notification of Panton-Valentine Leukocidin-Positive Methicillin-Resistant Staphylococcus aureus in Saxony, Germany: Analysis of Cases from the City of Leipzig in 2019

In Germany, Saxony is the only federal state where the detection of a Panton-Valentine Leukocidin (PVL)-positive Methicillin-resistant Staphylococcus aureus (MRSA) has to be notified to the local health authority (LHA). The LHA reports the case to the state health authority and introduces concrete infection control measures. We analyzed isolates from the respective cases in 2019, which were collected in local microbiological laboratories and sent to the National Reference Centre (NRC) for Staphylococci and Enterococci for strain characterization and typing. Antibiotic resistance testing was done by broth microdilution. Molecular characterization was performed using spa and SCCmec typing, MLST, and the PCR detection of marker genes associated with distinct MRSA lineages. Demographic and clinical data of the individual cases were assessed and the LHA performed epidemiological investigations. Thirty-nine (index) persons, diagnosed with a PVL-positive MRSA, were initially reported to the LHA. Most patients suffered from skin and soft-tissue infections (SSTI). For 21 of the index cases, household contacts were screened for MRSA. Seventeen out of 62 contacts were also colonized with a PVL-positive MRSA. The median age of altogether 58 individuals was 23.5 years. In over half of the cases, the home country was not Germany and/or a history of travel or migration was reported. Molecular characterization revealed the presence of various epidemic community-associated MRSA lineages, with "USA300", including the North American Epidemic (ST8-MRSA-IVa) and the South American Epidemic Clone (ST8-MRSA-IVc), the "Sri Lankan Clone" (ST5-MRSA-IVc), and the "Bengal Bay Clone" (ST772-MRSA-V) being more prevalent. In eight out of nine households, the contact persons were colonized with the same clone as the respective index case, suggesting a close epidemic and microbiological link. The obligation to report PVL-positive MRSA enables us to detect the occurrence of PVL-producing MRSA and its spread in the population as early as possible. Timely detection allows the targeted deployment of reliable anti-infective measures.

Characterization of Methicillin-resistant Staphylococcus aureus From Children at Hospital Admission: Experiences From a Hospital in a German Metropolitan Area

BACKGROUND

Since the 1990s, community-associated Methicillin-resistant Staphylococcus aureus (CA-MRSA) are described as emerging independent of health care. CA-MRSA is associated with the colonization and infection of healthy, immunocompetent younger individuals. While skin and soft tissue infections (SSTI) are predominant, life-threatening syndromes can also occur.

METHODS

In this retrospective study, we investigated MRSA stains isolated from community-onset infections and from MRSA screening of children at admission to a tertiary-care hospital in 2012-2018. In total, 102 isolates were subjected to antibiotic susceptibility testing by broth microdilution, spa -typing, multilocus sequence typing, SCC mec typing and virulence/resistance gene detection by polymerase chain reaction.

RESULTS

The majority of isolates originated from community-onset infections (80/102), of these primarily from SSTI (70/80). Additional strains were isolated by MRSA screening (22/102). In total 61.8% of the MRSA carried the gene for the Panton-Valentine leukocidin ( lukPV ). Molecular characterization of isolates revealed various epidemic MRSA clones, circulating in both community and hospital settings. Most prevalent epidemic lineages were isolates of the "European CA-MRSA clone" (CC80-MRSA-IV), the "Bengal Bay clone" (ST772-MRSA-V), or the "USA300 NAE clone" (ST8-MRSA-IVa).

CONCLUSIONS

Our data highlight the importance of CA-MRSA causing SSTI in children. More frequent microbiological and molecular analysis of these strains is important for targeted treatment and can provide valuable data for molecular surveillance of the pathogen.

Evaluation of virulence potential of methicillin-sensitive and methicillin-resistant Staphylococcus aureus isolates from a German refugee cohort

BACKGROUND

Community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) seem to be highly transmissible, often infect otherwise healthy humans and frequently occur in hospital outbreaks.

METHODS

Refugees, living in accommodations in Germany were screened for nasal carriage of S. aureus. The isolates were investigated regarding resistance and virulence, phenotypically and by whole genome data analysis.

RESULTS

5.6% (9/161) of the refugees are carriers of S. aureus. 2.5% (4/161) are MRSA carriers. Among the refugees, spa-types t021, t084, t304, t991 and t4983 were detected, as well as the new spa-types t18794 and t18795. t304 and t991 are assumed to be local spa-types from the middle east. The isolates are less resistant and marginal biofilm formers. Each isolate has a remarkable set of virulence genes, although genes, encoding for proteins strongly associated with invasive S. aureus infections, like Panton-Valentine leucocidin, were not detected.

CONCLUSION

The detection of strains from the middle east, supports the assumption that strains co-travel with the refugees and persist despite a transition of the host's living conditions. Whole genome data analysis does not permit to finally evaluate a germ's virulence. Nevertheless, an impression of the virulence potential of the strains, regarding skills in colonization, resistance, immune evasion, and host cell damaging can be pictured.

Staphylococcus aureus Interferes with Streptococci Spatial Distribution and with Protein Expression of Species within a Polymicrobial Oral Biofilm

We asked whether transient Staphylococcus aureus in the oral environment synergistically interacts with orally associated bacterial species such as Actinomyces oris, Candida albicans, Fusobacterium nucleatum, Streptococcus oralis, Streptococcus mutans, and Veillonella dispar (six-species control biofilm 6S). For this purpose, four modified biofilms with seven species that contain either the wild type strain of the S. aureus genotype (USA300-MRSA WT), its isogenic mutant with MSCRAMM deficiency (USA300-MRSA ΔMSCRAMM), a methicillin-sensitive S. aureus (ST72-MSSA-) or a methicillin-resistant S. aureus (USA800-MRSA) grown on hydroxyapatite disks were examined. Culture analyses, confocal-laser-scanning microscopy and proteome analyses were performed. S. aureus strains affected the amount of supragingival biofilm-associated species differently. The deletion of MSCRAMM genes disrupted the growth of S. aureus and the distribution of S. mutans and S. oralis within the biofilms. In addition, S. aureus caused shifts in the number of detectable proteins of other species in the 6S biofilm. S. aureus (USA300-MRSA WT), aggregated together with early colonizers such as Actinomyces and streptococci, influenced the number of secondary colonizers such as Fusobacterium nucleatum and was involved in structuring the biofilm architecture that triggered the change from a homeostatic biofilm to a dysbiotic biofilm to the development of oral diseases.

Detection and Molecular Characterization of Methicillin-Resistant Staphylococcus aureus from Table Eggs in Haripur, Pakistan

Table eggs are nutritionally important food consumed globally. Despite being protected inside the hard shell and a semipermeable membrane, the egg contents may be contaminated with microbes and thus become a possible carrier of infectious agents to humans. A number of medically significant bacterial species such as Salmonella enterica, Listeria monocytogenes, and Yersinia enterocolitica have already been reported from table eggs. More important is the presence of antimicrobial-resistant bacterial strains in this food source. The present study was aimed at detection and characterization of Staphylococcus aureus from table eggs collected from different retail shops in Haripur city of Pakistan. Staphylococci were isolated from 300 eggs collected from December 2015 to May 2016. S. aureus isolates were tested for antimicrobial susceptibility using broth microdilution and characterized using pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST), staphylococcal cassette chromosome mec (SCCmec) typing, and spa typing. The presence of Panton-Valentine leukocidin and antimicrobial resistance genes were detected using PCR. Staphylococci were isolated from 21.3% (64/300) of the table eggs tested. Of those, 59% (38/64) were identified as S. aureus, of which 33 (86.8%) were positive for mecA (MRSA, methicillin-resistant S. aureus). All MRSA were multidrug resistant (resistant to two or more antimicrobial classes), contained aac-aph (encoding aminoglycosides), and were pvl⁺. Using MLST, spa typing, and SCCmec typing, three genotypic patterns were assigned: ST8-t8645-MRSA-IV, associated with USA300; and ST772-t657-MRSA-IV and ST772-t8645-MRSA-IV, both characteristic of the Bengal Bay community-associated MRSA clone. Molecular typing by PFGE revealed that the bacterial population was highly homogenous with only two patterns observed. This study is the first report of detection of human-associated pvl⁺ MRSA from table eggs. The genetic similarities of MRSA present in the eggs to that of humans may suggest human to poultry transmission of MRSA via contamination.

Molecular Epidemiology of Staphylococcus aureus in the General Population in Northeast Germany: Results of the Study of Health in Pomerania (SHIP-TREND-0)

Population-based studies on Staphylococcus aureus nasal colonization are scarce. We examined the prevalence, resistance, and molecular diversity of S. aureus in the general population in Northeast Germany. Nasal swabs were obtained from 3,891 adults in the large-scale population-based Study of Health in Pomerania (SHIP-TREND). Isolates were characterized using spa genotyping, as well as antibiotic resistance and virulence gene profiling. We observed an S. aureus prevalence of 27.2%. Nasal S. aureus carriage was associated with male sex and inversely correlated with age. Methicillin-resistant S. aureus (MRSA) accounted for 0.95% of the colonizing S. aureus strains. MRSA carriage was associated with frequent visits to hospitals, nursing homes, or retirement homes within the previous 24 months. All MRSA strains were resistant to multiple antibiotics. Most MRSA isolates belonged to the pandemic European hospital-acquired MRSA sequence type 22 (HA-MRSA-ST22) lineage. We also detected one livestock-associated MRSA ST398 (LA-MRSA-ST398) isolate, as well as six livestock-associated methicillin-susceptible S. aureus (LA-MSSA) isolates (clonal complex 1 [CC1], CC97, and CC398). spa typing revealed a diverse but also highly clonal S. aureus population structure. We identified a total of 357 spa types, which were grouped into 30 CCs or sequence types. The major seven CCs (CC30, CC45, CC15, CC8, CC7, CC22, and CC25) included 75% of all isolates. Virulence gene patterns were strongly linked to the clonal background. In conclusion, MSSA and MRSA prevalences and the molecular diversity of S. aureus in Northeast Germany are consistent with those of other European countries. The detection of HA-MRSA and LA-MRSA within the general population indicates possible transmission from hospitals and livestock, respectively, and should be closely monitored.

Recovery of a 10-year-old girl from methicillin-resistant Staphylococcus aureus sepsis in response to low-dose ceftaroline treatment

A 9-year-old girl was severely injured in a car accident in Afghanistan, in which both her lower legs were badly damaged. She was treated at the Hospital of Ingolstadt (Klinikum Ingolstadt) after she had undergone initial surgery at an Indian hospital. Various bacterial species were isolated from multiple wounds, and methicillin-resistant Staphylococcus aureus (MRSA) was one among them. After the amputation of her lower legs, she developed MRSA sepsis, which was successfully treated with a relatively low dosage of ceftaroline (Zinforo(®)/Teflaro(®); 2×9 mg/kg/d), although the bacterial isolate's minimal inhibitory concentration (1.5-4 mg/L) suggested a decreased susceptibility. In summary, ceftaroline was highly efficient and well tolerated by the patient suffering from MRSA sepsis.

Staphylococcus aureus nasal carriage among healthcare workers in Kisangani, the Democratic Republic of the Congo

Methicillin-resistant Staphylococcus aureus (MRSA) is a global health concern, but there are few data from Central Africa. The objective of our study was to characterise S. aureus colonisation isolates from healthcare-exposed professionals in the Democratic Republic of the Congo (DRC). Healthcare workers and medical students (n = 380) in Kisangani, DRC were screened for S. aureus nasal carriage in a single-centre cross-sectional study in the University Hospital of Kisangani. The isolates were identified and characterised using phenotypic and genotypic methods. The nasal carriage rate of S. aureus was 16.6 % and 10 out of 63 isolates (15.9 %) were MRSA. We found 28 different spa types. Most MRSA isolates belonged to ST8-spa t1476-SCCmec V. The majority of MRSA were multidrug-resistant to non-beta-lactam antibiotics. Overall, 28.5 % of S. aureus carried Panton-Valentine leucocidin (PVL)-encoding genes (all methicillin-sensitive) and 17.5 % carried toxic shock syndrome toxin-1 (TSST-1)-encoding genes. The finding of MRSA carriage among healthcare workers in a setting with limited access to diagnostic microbiology and appropriate therapy calls for improved education on infection control practices and supports the introduction of surveillance programmes.

Clonality and antimicrobial susceptibility of methicillin-resistant Staphylococcus aureus at the University Hospital Zurich, Switzerland between 2012 and 2014

Background

Methicillin-resistant Staphylococcus aureus (MRSA) is a global epidemic threat. The aim of this study was to determine which globally known MRSA lineages are currently present at our tertiary care hospital in Switzerland, a hospital with low MRSA prevalence. In light of the increasing prevalence of multi drug resistance including vancomycin resistance we also assessed antibiotic susceptibilities.

Methods

The 146 MRSA strains collected over two years (March 2012 until February 2014) at the University Hospital Zurich, Switzerland, were analyzed by PFGE analysis of SmaI digests in combination with spa-typing. In addition, representative isolates were analyzed by multi locus sequence typing (MLST). Susceptibilities to eight antibiotics were assessed using the Kirby-Bauer disc diffusion method.

Results

Isolates showed resistance to erythromycin (48%), ciprofloxacin (43%), clindamycin (31%), tetracycline (22%), and gentamicin (16%). All isolates were susceptible to vancomycin, 95% were susceptible to sulfamethoxazole/trimethoprim and rifampicin, respectively. PFGE analysis revealed 22 different patterns, with four major patterns that accounted for 53.4% of all MRSA isolates, and seven sporadic patterns. Spa typing revealed 50 different spa types with the predominant types being t008 (14%), t002 (10%), and t127 (9%). 82% of the MRSA isolates could be assigned to six clonal complexes (CCs) namely CC1 (10%), CC5 (23%), CC8 (18%), CC22 (17%), CC30 (11%), and CC45 (3%) based on spa-types, PFGE patterns, and MLST. Two isolates could not be typed by either PFGE analysis or spa-typing and three isolates had spa-types that have not yet been described.

Conclusions

The combination of the two typing methods was more discriminatory as compared to the use of a single method. Several of the lineages that are predominant in Europe are present in our hospital. Resistances to antibiotics have decreased in comparison to a study conducted between 2004 and 2006.

Electronic supplementary material

The online version of this article (doi:10.1186/s12941-015-0075-3) contains supplementary material, which is available to authorized users.

Community-associated methicillin-resistant Staphylococcus aureus clonal complex 80 type IV (CC80-MRSA-IV) isolated from the Middle East: a heterogeneous expanding clonal lineage

Background

The emergence of community-associated methicillin resistant Staphylococcus aureus (CA-MRSA) has caused a change in MRSA epidemiology worldwide. In the Middle East, the persistent spread of CA-MRSA isolates that were associated with multilocus sequence type (MLST) clonal complex 80 and with staphylococcal cassette chromosome mec (SCCmec) type IV (CC80-MRSA-IV), calls for novel approaches for infection control that would limit its spread.

Methodology/Principal Findings

In this study, the epidemiology of CC80-MRSA-IV was investigated in Jordan and Lebanon retrospectively covering the period from 2000 to 2011. Ninety-four S. aureus isolates, 63 (67%) collected from Lebanon and 31 (33%) collected from Jordan were included in this study. More than half of the isolates (56%) were associated with skin and soft tissue infections (SSTIs), and 73 (78%) were Panton-Valentine Leukocidin (PVL) positive. Majority of the isolates (84%) carried the gene for exofoliative toxin d (etd), 19% had the Toxic Shock Syndrome Toxin-1 gene (tst), and seven isolates from Jordan had a rare combination being positive for both tst and PVL genes. spa typing showed the prevalence of type t044 (85%) and pulsed-field gel electrophoresis (PFGE) recognized 21 different patterns. Antimicrobial susceptibility testing showed the prevalence (36%) of a unique resistant profile, which included resistance to streptomycin, kanamycin, and fusidic acid (SKF profile).

Conclusions

The genetic diversity among the CC80 isolates observed in this study poses an additional challenge to infection control of CA-MRSA epidemics. CA-MRSA related to ST80 in the Middle East was distinguished in this study from the ones described in other countries. Genetic diversity observed, which may be due to mutations and differences in the antibiotic regimens between countries may have led to the development of heterogeneous strains. Hence, it is difficult to maintain “the European CA-MRSA clone” as a uniform clone and it is better to designate as CC80-MRSA-IV isolates.

Detection of livestock-associated methicillin-resistant Staphylococcus aureus among swine workers in Romania

BACKGROUND

Methicillin-resistant Staphylococcus aureus (MRSA) is a devastating pathogen that is associated with high morbidity and mortality worldwide. Livestock are a well-known reservoir for this pathogen, which poses substantial health risks for livestock workers. Little is known about the epidemiology of livestock-associated MRSA (LA-MRSA) among livestock workers in Eastern Europe.

METHODS

To study the epidemiology of LA-MRSA among swine workers in Romania, we collected and characterized nasal and oropharygneal samples from swine workers on commercial pig farms. A survey that included questions about work-related tasks, biosafety practices, contact with animals, and health status was used to assess the risk factors that were potentially associated with LA-MRSA colonization.

RESULTS

The prevalence of MRSA colonization among swine workers was 6.8%. Two LA-MRSA strains with the spa types t034 and t011 and one likely community-associated MRSA strain with the spa type t321 were isolated from workers on five farms. Interestingly, all MRSA carriers worked on farms that imported animals from other production facilities.

CONCLUSION

This is the first study to confirm the presence of LA-MRSA among swine workers in Romania and suggests the need to minimize the risk of LA-MRSA-related infections in swine workers and their community contacts. The findings also suggest a link between the commercial movement of swine and the introduction of LA-MRSA.

Carriage of methicillin-resistant staphylococci by healthy companion animals in the US

Antimicrobial-resistant staphylococci have been associated with wounded or ill companion animals, but little is known about the prevalence of resistant staphylococci among healthy animals. In this study, 276 healthy dogs and cats from veterinary clinics were tested for the presence of antimicrobial-resistant Staphylococcus spp. Isolates were tested for antimicrobial susceptibility and the presence of select resistance genes, and typed using Pulsed-Field Gel Electrophoresis (PFGE). Staphylococcus aureus and Staphylococcus pseudintermedius were also characterized using multilocus sequence typing (MLST), spa typing and SCCmec typing. Approximately 5% (14/276) of the animals were positive by enrichment for five species of staphylococci [Staph. aureus (n = 11), Staph. pseudintermedius (n = 4), Staphylococcus sciuri (n = 6), Staphylococcus simulans (n = 1) and Staphylococcus warneri (n = 1)]. Seventy-eight per cent (18/23) of staphylococci were resistant to oxacillin and also multidrug resistant (resistance to ≥ 2 antimicrobials). All Staph. aureus isolates were mecA+ and blaZ+, SCCmec type II, spa type t002, ST5 and clonal using PFGE. Staphylococcus pseudintermedius were SCCmec type IV or V, spa type t06 and ST170; two of the isolates were pvl(+) . These results suggest that healthy companion animals may be a reservoir of multidrug-resistant staphylococci, which may be transferred to owners and others who handle companion animals.

SIGNIFICANCE AND IMPACT OF THE STUDY

In this study, antimicrobial-resistant coagulase-negative and coagulase-positive staphylococci were isolated from various body sites on healthy dogs and cats. Resistance to 14 antimicrobials was observed including resistance to oxacillin; the majority of staphylococci were also multidrug resistant. Results from this study suggest that healthy dogs and cats may act as reservoirs of antimicrobial-resistant bacteria that may be transferred to people by simple interaction with the animals. Such carriage poses an underlying risk of infection, which should be considered during handling of healthy dogs and cats by pet owners and veterinary personnel.

Dissemination of methicillin-resistant Staphylococcus aureus SCCmec type IV and SCCmec type V epidemic clones in a tertiary hospital: challenge to infection control

Two-hundred MRSA strains from inpatients with healthcare-associated (HA) and 100 MRSA strains from outpatients with community-associated (CA) skin and soft tissue infections (SSTIs) were tested for antimicrobial susceptibility, staphylococcal cassette chromosome mec (SCCmec) typing, Panton-Valentine leucocidin (PVL) toxin, seh and arcA genes. Based on SCCmec typing, HA-MRSA isolates were further divided into HA-SCCmec I/II/III MRSA and HA-SCCmec IV/V MRSA, and CA-MRSA isolates into CA-SCCmec I/II/III MRSA and CA-SCCmec IV/V MRSA. SCCmec types were further characterized by pulsed-field gel electrophoresis, spa typing and multi-locus sequence typing. Seventy-five (37·5%) HA-MRSA isolates and 83/100 CA-MRSA isolates were SCCmec IV/V genotype. HA-SCCmec IV/V MRSA was associated with malignancy (P = 0·03) and bone fractures (P = 0·02) compared to CA-SCCmec IV/V MRSA. HA-SCCmec IV/V MRSA was associated with PVL gene carriage compared to HA-SCCmec I/II/III MRSA (P < 0·001). ST22-MRSA-IV (EMRSA-15), ST772-MRSA-V, and ST36-MRSA-IV and ST239:EMRSA-I:III were the major clones identified. Our study documents the emergence of SCCmec IV and SCCmec V MRSA clones in an Indian hospital.

Evaluation of Daptomycin Non-Susceptible Staphylococcus aureus for Stability, Population Profiles, mprF Mutations, and Daptomycin Activity

Introduction

Despite studies examining daptomycin non-susceptible (DNS) Staphylococcus aureus, examination of the stability and population profiles is limited. The objective was to evaluate the stability, population profiles, and daptomycin activity against DNS isolates.

Methods

The stability of 12 consecutive clinical DNS strains was evaluated by minimum inhibitory concentration (MICs) and population analysis profiles before and after 5 days of serial passage. Two pairs of DNS S. aureus having the same daptomycin MIC but different daptomycin population profiles were evaluated via an in vitro pharmacokinetic/pharmacodynamic (PK/PD) model of simulated endocardial vegetations for 96 h against daptomycin 6 and 10 mg/kg/day. The sequence of mprF was determined for these isolates before and after 96 h of daptomycin exposure in the in vitro PK/PD model.

Results

Daptomycin MIC values were 2–4 mg/L (via Microscan) for the 12 clinical isolates; 9 were confirmed DNS and 3 were within 1 tube dilution of Microscan (daptomycin MIC 1 mg/L). All were stable to serial passage. There was variation in the isolates susceptibility to daptomycin on population analysis (daptomycin population AUC 14.01–26.85). The killing patterns of daptomycin 6 and 10 mg/kg/day differed between isolates with a left-shift and right-shift population profile to daptomycin. Two strains developed additional mprF mutations during daptomycin exposure in the in vitro PK/PD model resulting in P314L, L826F, S337L and a novel Q326Stop mutation.

Conclusions

The collection of DNS isolates was stable and displayed variation in susceptibility to daptomycin on population profile. Further research examining this clinical relevance is warranted.

Electronic supplementary material

The online version of this article (doi:10.1007/s40121-013-0021-7) contains supplementary material, which is available to authorized users.

Rapid detection of methicillin-resistant Staphylococcus aureus by a newly developed dry reagent-based polymerase chain reaction assay

BACKGROUND/PURPOSE

Methicillin-resistant Staphylococcus aureus (MRSA) is a major pathogen responsible for significant numbers of nosocomial and community-acquired infections worldwide. Molecular diagnosis for MRSA nasal carriers is increasingly important for rapid detection and screening of MRSA colonization because the conventional methods are time consuming and labor intensive. However, conventional polymerase chain reaction (PCR) tests still require cold-chain storage as well as trained personnel, which makes them unsuitable for rapid high-throughput analysis. The aim of this study was to develop a thermostabilized PCR assay for MRSA in a ready-to-use form that requires no cold chain.

METHODS

The thermostabilized PCR assay detects the following targets simultaneously: (1) 16S rRNA of the Staphylococcus genus; (2) femA gene specific for S. aureus; (3) mecA gene conferring methicillin resistance; and (4) lukS gene, which encodes the virulent toxin. The thermostabilized PCR incorporates an internal amplification control that helps to verify the presence of PCR inhibitors in samples. PCR reagents and specific primers were lyophilized into a pellet form with an enzyme stabilizer.

RESULTS

The PCR was validated with 235 nasal swabs specimens and was found to be 100% sensitive and specific. The stability of the thermostabilized PCR was evaluated using the Q10 method and it was found to be stable for approximately 6 months at 24 °C. The limit of detection of thermostabilized PCR assay was determined by probit regression (95% confidence interval) was 10(6) colony forming units at the bacterial cell level and 10 ng of DNA at the genomic DNA level, which is comparable with conventional PCR methods.

CONCLUSION

A rapid thermostabilized PCR assay that requires minimal pipetting steps and is cold chain-free was developed for detecting MRSA nasal carriers.

Novel methicillin-resistant coagulase-negative Staphylococcus clone isolated from patients with haematological diseases at the Blood Bank Centre of Amazon, Brazil

Methicillin-resistant Staphylococcus remains a severe public health problem worldwide. This research was intended to identify the presence of methicillin-resistant coagulase-negative staphylococci clones and their staphylococcal cassette chromosome mec (SCCmec)-type isolate from patients with haematologic diseases presenting bacterial infections who were treated at the Blood Bank of the state of Amazonas in Brazil. Phenotypic and genotypic tests, such as SCCmec types and multilocus sequence typing (MLST), were developed to detect and characterise methicillin-resistant isolates. A total of 26 Gram-positive bacteria were isolated, such as: Staphylococcus epidermidis (8/27), Staphylococcus intermedius (4/27) and Staphylococcus aureus (4/27). Ten methicillin-resistant staphylococcal isolates were identified. MLST revealed three different sequence types: S. aureus ST243, S. epidermidis ST2 and a new clone of S. epidermidis, ST365. These findings reinforce the potential of dissemination presented by multi-resistant Staphylococcus and they suggest the introduction of monitoring actions to reduce the spread of pathogenic clonal lineages of S. aureus and S. epidermidis to avoid hospital infections and mortality risks.

Prevalence and characterization of methicillin-resistant Staphylococcus aureus isolates from retail meat and humans in Georgia

There is increasing interest in the presence of Staphylococcus aureus, specifically methicillin-resistant S. aureus (MRSA), on retail meat products. In this study, staphylococci were isolated from retail pork and retail beef in Georgia, and MRSA from the products was compared to human MRSA from the same geographic area using broth microdilution antimicrobial susceptibility testing, multilocus sequence typing (MLST), spa typing, SCCmec typing, and pulsed-field gel electrophoresis (PFGE). S. aureus was isolated from 45% (45/100) of pork products and 63% (63/100) of beef products; mecA was detected in S. aureus from both pork (3/100; 3%) and beef (4/100; 4%). Fifty percent (50/100) of human S. aureus also contained mecA. Multidrug resistance was detected among MRSA from all sources. All MRSA (n = 57) was SCCmec type IV, and nine different spa types were present among the isolates (t002, t008, t012, t024, t179, t337, t548, t681, and t1062). Four sequence types (ST5, ST8, ST9, and ST30) were detected using MLST; the majority of MRSA isolates belonged to ST8, followed by ST5. One retail beef MRSA isolate belonged to ST8, while the remaining three were ST5. In retail pork MRSA, ST5, ST9, and ST30 were observed. The majority of human MRSA isolates belonged to ST8. Thirty-seven MRSA isolates, one of which was a retail beef MRSA isolate, were pvl(+). Using PFGE, MLST, and spa typing, three retail beef MRSA isolates were found to be identical in PFGE pattern, ST, and spa type to two human clonal MRSA isolates (USA100 and USA300). One additional retail beef MRSA isolate had a PFGE pattern similar to that of a human MRSA isolate, whereas none of the retail pork MRSA isolates had PFGE patterns similar to those of human MRSA isolates. These data suggest that the retail beef samples were contaminated by a human source, possibly during processing of the meat, and may present a source of MRSA for consumers and others who handle raw meat.

Community-acquired methicillin-resistant Staphylococcus aureus clones circulating in Belgium from 2005 to 2009: changing epidemiology

The present study reports the evolution of the demographic characteristics and the molecular epidemiology of community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) in Belgium from 2005 to 2009. Four hundred and ten CA-MRSA isolates were prospectively collected and screened for the presence of Panton-Valentin leucocidin (PVL) and toxic shock syndrome toxin 1 (TSST-1) encoding genes, while clinical information were recorded. PVL- and TSST-1-positive isolates were genotyped by pulsed-field gel electrophoresis (PFGE). Staphylococcal cassette chromosome mec (SCCmec) type, spa type and multilocus sequence type (MLST) were determined on representative isolates. One hundred and fifty-nine (39 %) isolates were PVL-positive. PVL-positive isolates were significantly more frequently isolated from skin or soft tissue than PVL-negative isolates, causing mainly subcutaneous abscesses and furuncles. Patients with PVL-positive CA-MRSA were significantly younger than patients with PVL-negative CA-MRSA. Eighty-seven percent of the PVL-positive isolates belonged to a limited number (n = 7) of PFGE types belonging to sequence types (ST) ST80, ST8, ST30, ST5, ST152, ST338 and a new ST, a single-locus variant of ST1. A temporal evolution of the distribution of these PFGE types was observed, characterised by (1) the dissemination of the ST8-SCCmecIV arcA-positive (USA300) genotype and (2) a genetic diversification. Forty-seven (11 %) strains were TSST-1-positive, of which 65 % clustered into four PFGE types, all belonging to ST5. The epidemiology of CA-MRSA in Belgium is changing, as the rapid diffusion of the USA300 clone seems to occur, together with a clonal diversification.

Methicillin-resistant Staphylococcus aureus (MRSA) detected at four U.S. wastewater treatment plants

BACKGROUND

The incidence of community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) infections is increasing in the United States, and it is possible that municipal wastewater could be a reservoir of this microorganism. To date, no U.S. studies have evaluated the occurrence of MRSA in wastewater.

OBJECTIVE

We examined the occurrence of MRSA and methicillin-susceptible S. aureus (MSSA) at U.S. wastewater treatment plants.

METHODS

We collected wastewater samples from two Mid-Atlantic and two Midwest wastewater treatment plants between October 2009 and October 2010. Samples were analyzed for MRSA and MSSA using membrane filtration. Isolates were confirmed using biochemical tests and PCR (polymerase chain reaction). Antimicrobial susceptibility testing was performed by Sensititre® microbroth dilution. Staphylococcal cassette chromosome mec (SCCmec) typing, Panton-Valentine leucocidin (PVL) screening, and pulsed field gel electrophoresis (PFGE) were performed to further characterize the strains. Data were analyzed by two-sample proportion tests and analysis of variance.

RESULTS

We detected MRSA (n = 240) and MSSA (n = 119) in 22 of 44 (50%) and 24 of 44 (55%) wastewater samples, respectively. The odds of samples being MRSA-positive decreased as treatment progressed: 10 of 12 (83%) influent samples were MRSA-positive, while only one of 12 (8%) effluent samples was MRSA-positive. Ninety-three percent and 29% of unique MRSA and MSSA isolates, respectively, were multidrug resistant. SCCmec types II and IV, the pvl gene, and USA types 100, 300, and 700 (PFGE strain types commonly found in the United States) were identified among the MRSA isolates.

CONCLUSIONS

Our findings raise potential public health concerns for wastewater treatment plant workers and individuals exposed to reclaimed wastewater. Because of increasing use of reclaimed wastewater, further study is needed to evaluate the risk of exposure to antibiotic-resistant bacteria in treated wastewater.

Genetic characterization of Panton-Valentine leukocidin-producing methicillin-resistant Staphylococcus aureus in Western Austria

BACKGROUND

Community-acquired methicillin-resistant Staphylococcus aureus (caMRSA) is an emerging pathogen which causes potentially severe infections in young and healthy individuals due to the ability of most strains to produce Panton-Valentine leukocidin (PVL). The aim of this study was to evaluate the prevalence of PVL-positive (PVL(+))-MRSA strains in Western Austria in the period from December 2005 to May 2010 and to characterize the identified PVL(+)-MRSA strains.

METHODS

Six hundred and fifty MRSA strains from Innsbruck Medical University hospital, district hospitals, and general practitioners were investigated for the presence of lukS-lukF gene (encoding for PVL). Antimicrobial resistance testing, SCCmec-, agr-, MLST- and spa-typing, as well as arcA determination were performed on PVL(+)-MRSA.

RESULTS

Among 650 MRSA strains collected from various body sites from hospitalized patients and outpatients, 31 strains (4.8 %) were positive for lukS-lukF and thus identified as PVL(+)-MRSA. Agr-1 was the most common agr-type (n = 18, 58.1 %) and SCCmec-IV or variants IVa and IVc were the most common SCCmec types (n = 27, 87.1 %). All tested strains showed in-vitro susceptibility to vancomycin and rifampicin, but resistance against cotrimoxazol (6.4 %), clindamycin (9.7 %), gentamicin (9.7 %), fusidic acid (12.9 %), levofloxacin (12.9 %), and erythromycin (61.3 %) was found. Most lukS-lukF-positive MRSA detected in our survey shared ST8 and t008 and were positive for arcA.

CONCLUSIONS

The major lukS-lukF-positive MRSA lineage found in our population was ST8, t008 and positive for arcA which is mainly found in the USA. In contrast, ST80 strains were not found as frequently in our region as in many other European countries.

Successful treatment of a left ventricular assist device infection with daptomycin non-susceptible methicillin-resistant Staphylococcus aureus: case report and review of the literature

Recipients of left ventricular assist devices (LVADs) are highly susceptible to the development of infections with multidrug-resistant (MDR) organisms. We describe the case of a patient with an LVAD who developed a device-related, daptomycin non-susceptible, methicillin-resistant Staphylococcus aureus infection, highlighting this patient population as highly vulnerable to the development of such antimicrobial resistance. This report includes a thorough review of the literature on the mechanisms of development of daptomycin non-susceptibility and suggests ways to prevent its emergence. We also provide and underscore the appropriate guidelines to abide by when attempting to control infections with such resistant isolates. This case also demonstrates the importance of definitive treatment with LVAD removal and transplantation as a component of appropriate management of invasive LVAD infections. In addition, we suggest that even infections with MDR organisms may not adversely affect post-transplant outcomes.

The length of the Staphylococcus aureus protein A polymorphic region regulates inflammation: impact on acute and chronic infection

Staphylococcus aureus protein A (SpA) plays a critical role in the induction of inflammation. This study was aimed to determine whether the number of short sequence repeats (SSRs) present in the polymorphic region modulates the inflammatory response induced by SpA. We demonstrated that there is a dose-response effect in the activation of interferon (IFN)-β signaling in airway epithelial and immune cells, depending on the number of SSRs, which leads to differences in neutrophil recruitment. We also determined that a significant proportion of isolates from patients with chronic infections such as osteomyelitis and cystic fibrosis carry fewer SSRs than do isolates from patients with acute infections or healthy carriers and that there was an inverse correlation between the number of SSRs and the length of disease course. Given the importance of IFN signaling in eradication of S. aureus, loss of SSRs may represent an advantageous mechanism to adapt to and persist in the host.

Rapid identification of community-associated methicillin-resistant Staphylococcus aureus by Fourier transform infrared spectroscopy

The emergence of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) carrying Panton-Valentine leukocidin is a worldwide problem. Their identification is based currently on costly and complicated molecular methods. This article describes a simple method for differentiating CA-MRSA from hospital-associated (HA) epidemic MRSA pulsed-field gel electrophoresis types using Fourier transform infrared (FTIR) spectroscopy. The 47 CA-MRSA isolates included 3 Southwest Pacific (resembling USA1100), 24 CMRSA7 (resembling USA400/MW2), 19 CMRSA10 (resembling USA300), and 1 European ST80, while HA-MRSA were represented by 27, 16, 11, 15, 7, and 8 Canadian epidemic isolates CMRSA1 through CMRSA6 respectively, plus 25 nontyped Canadian HA-MRSA. Principal component analysis (PCA), self-organized maps (SOMs), and the K-nearest neighbor (KNN) method were used to cluster the isolates based on chemometric analysis of FTIR spectra of dried films of stationary-phase cells grown on Que-Bact® Universal Medium No. 2 (Quelab Laboratories, Montreal, QC, Canada). First-derivative normalized data from a single narrow spectral region (1361-1236 cm(-1), suggesting differences in protein amide III and nucleic acid phosphodiester contents) allowed 98% correct classification by KNN, 93% by SOMs, and 92% by PCA. FTIR spectroscopic analysis of cells grown on Que-Bact® Universal Medium No. 2 offers a rapid and simple alternative to molecular methods for routine identification of CA-MRSA epidemic isolates.

Antibiotic resistance and molecular epidemiology of Staphylococcus aureus in Nigeria

BACKGROUND

Staphylococcus aureus is an important pathogen causing a wide range of infections in the hospital and community setting. In order to have adequate information for treatment of S. aureus infections, it is crucial to understand the trends in the antibiotic-resistance patterns. In addition, the occurrence and changes in types of S. aureus, clonal identities, and their geographic spread is essential for the establishment of adequate infection control programmes. In this study, 68 S. aureus isolates obtained from clinical and non-clinical sources in Nigeria between January and April 2009 were characterized using phenotypic and molecular methods.

RESULTS

All the S. aureus isolates were susceptible to teicoplanin, vancomycin, phosphomycin, fusidic acid, rifampicin, daptomycin, mupirocin, linezolid and tigecycline. Sixteen percent of the isolates were resistant to oxacillin, while 55% and 72% of isolates were resistant to tetracycline and trimethoprim/sulphamethoxazole (cotrimoxazole), respectively (Table 1). There was excellent correlation between the broth microdilution assay and detection of antibiotic resistance genes by the multiplex PCR, in the determination of S. aureus resistance to erythromycin, gentamicin, methicillin and tetracycline. A total of 28 spa types were identified in the study, and the predominant spa type among the methicillin-susceptible S. aureus (MSSA) isolates was t084 (13 isolates). The t037-ST241-SCCmecIII type was the only clone identified in Maiduguri (North-East Nigeria) while in South-West Nigeria, diversity among the MRSA isolates (t451-ST8-SCCmecV; t008-ST94-SCCmecIV; t002-ST5-SCCmecV; t064-ST8-SCCmecV) was observed. The toxin genes seh and etd were detected in isolates affiliated with clonal complexes CC1, CC80 and sequence type ST25, respectively. The proportion of PVL-positive isolates among MSSA was high (40%). Most of the PVL-positive MSSA isolates were obtained from wound infections and associated with clonal complexes CC1, CC30, CC121 and with sequence type ST152.

CONCLUSIONS

The use of phenotypic and molecular methods provided useful information on antibiotic resistance and molecular diversity of S. aureus in Nigeria. The high proportion of PVL-positive MSSA isolates affiliated to various clonal complexes and detected in all the health institutions is a major concern, both as a source of severe infections and as a potential reservoir that could lead to the emergence of PVL-positive MRSA. This study presents the first baseline information on the nature of the antibiotic resistance genes from S. aureus isolates in Nigeria. There is the need to curtail the spread and establishment of MRSA and PVL-positive MSSA clones in Nigerian health care institutions.

Trends in the occurrence of MRSA strains in Upper Austria from 2006 to 2009

Between 2006 and 2009, all MRSA isolates recovered from human patients in Upper Austria were subjected to molecular biological analysis. Whereas the isolate number decreased from year to year, the proportion of the most common sequence types (ST5, ST8 and ST22) as well as the frequency of associated PFGE subtypes and spa-types remained similar. The rate of PVL-positive MRSA increased, whereupon the most common sequence types were ST152, ST8 including clone USA300, ST5, ST777 and ST88. The frequency of ST398 was high (25%) in relation to the PVL-positive clones. Thus, we consider a special focus on community-associated MRSA to be necessary.

Emergence of methicillin-resistant Staphylococcus aureus (MRSA) in different animal species

The emergence of methicillin-resistant Staphylococcus aureus (MRSA) in animals such as horses, pet animals and productive livestock has raised questions of a probable human origin and in more general of host specificity of S. aureus. Particular clonal lineages are obviously specific for humans (e.g. ST15, ST25, ST45) and other for ruminants (e.g. ST151). MRSA associated with veterinary nosocomial infections (e.g. ST8 and ST254 in horses, ST22 in small animals) very likely have their origin in health care facilities. MRSA ST398 which became first known from widespread colonization in industrially raised pigs seems to have a limited host specificity and is able to colonize and to cause infections in various hosts. Mechanisms of host adaptation and their genomic background are poorly understood so far.

Central nervous system invasion by community-acquired meticillin-resistant Staphylococcus aureus

We report a case of community-acquired meticillin-resistant Staphylococcus aureus (CA-MRSA) bacteraemia with cavernous sinus thrombosis, meningitis and brain abscess in a previously healthy American, who was employed in Belgium. We consecutively reviewed all published cases of CA-MRSA with central nervous system (CNS) involvement. A total of 12 similar cases were found, of which 11 were published in the last 4 years. Predominantly, young previously healthy subjects were affected (median age 28 years). The cases involved brain abscesses (5/12), disseminated disease (4/12), cavernous sinus thrombosis (2/12) and other (1/12). Infection origins were superficial skin infections (5/12), mostly of the face, sinusitis (1/12), otitis media (1/12), other or unknown (5/12). Although, in our review of the literature patients treated with linezolid had a better outcome compared to patients treated with vancomycin, the latter is still the mainstay of therapy for CNS infections associated with MRSA.

Cross-border dissemination of methicillin-resistant Staphylococcus aureus, Euregio Meuse-Rhin region

MRSA clones were associated with hospital-associated clonal complexes and with Panton-Valentine leukocidin–positive community-associated MRSA.

Because the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) differs among the 3 countries forming the Euregio Meuse-Rhin (EMR) region (Belgium, Germany, and the Netherlands), cross-border healthcare requires information about the spread of MRSA in the EMR. We investigated the emergence, dissemination, and diversity of MRSA clones in the EMR by using several typing methods. MRSA associated with clonal complexes 5, 8, 30, and 45 was disseminated throughout the EMR. Dutch isolates, mainly associated with sequence types (ST) ST5-MRSA-II, ST5-MRSA-IV, ST8-MRSA-IV, and ST45-MSRA-IV had a more diverse genetic background than the isolates from Belgium and Germany, associated with ST45-MRSA-IV and ST5-MRSA-II, respectively. MRSA associated with pigs (ST398-MRSA-IV/V) was found in the Dutch area of the EMR. Five percent of the MRSA isolates harbored Panton-Valentine leukocidin and were classified as community-associated MRSA associated with ST1, 8, 30, 80, and 89.

Community-Acquired Methicillin-Resistant Staphylococcus aureus (CA-MRSA) Colonization and Infection in Intravenous and Inhalational Opiate Drug Abusers

Methicillin-resistant Staphylococcus aureus (MRSA) is a significant pathogen in hospital-acquired and community-acquired infections. We hypothesized that drug abuse is a risk factor for community-acquired MRSA (CA-MRSA) infection, and we employed a rapid multiplex PCR technique for MRSA identification. The study was conducted on MRSA isolates from 60 opiate addicts (intravenous and inhalational drug users) to detect the rate and location of MRSA colonization and infection among them in comparison to 60 non-addict patients and 15 healthy volunteer controls. The proportion of addicts with MRSA colonization (and/or infection) was significantly higher than non-addict patients with MRSA colonization. MRSA colonization was associated with infection in 58% of MRSA-colonized addicts. The MRSA nasal carriage in the addicts was significantly higher than MRSA carriage elsewhere, whether in the addicts group or in the non-addict patients group. Moreover, the nasopharyngeal carriage rate of MRSA among addicts was significantly higher than among the non-addict patients. Increasing the duration of addiction resulted in a significant increase in CA-MRSA colonization in opiate addicts. Both inhalational and intravenous drug use led to significant MRSA colonization in the addict population. In conclusion, this study demonstrated how drug abusers, a high-risk group for infections with MRSA, could be a source or a reservoir of CA-MRSA infection in the non-addict population.