Community-associated methicillin-resistant Staphylococcus aureus in non-outbreak skin infections

Insights into the epidemiology of community-associated methicillin-resistant Staphylococcus aureus in special populations and at the community-healthcare interface

The current epidemic proportions of infections caused by Staphylococcus aureus strains and especially by methicillin-resistant S. aureus (MRSA) are one of today's many threats to global public health, particularly in underdeveloped countries where significant gaps on the subject exist. The rapid spread and diversification of pandemic clones that exhibit remarkably increasing virulence and antimicrobial resistance pose a risk to the effective prevention and treatment of a wide range of infections. Undoubtedly, the remarkable versatility involving the pathogenesis and resistance of these bacteria is perpetuated through geographic and temporal factors inherent to clonal evolution and is reflected in the dramatic epidemiological changes of MRSA which, after decades prevailing in healthcare settings, have emerged in the community. Denominated community-associated [CA]-MRSA, these strains are particularly prevalent in some population groups, facilitating the spread of successful clones that are potentially capable of triggering severe community-acquired infections. Therefore, a broad approach to local epidemiological aspects in less studied regions, but nonetheless at latent risk of endemic spread that may reach global proportions, is necessary. In Brazil, despite limited molecular epidemiology data, CA-MRSA strains predominantly characterized as SCCmec IV, often classified as CC30-ST30, CC5-ST5 and CC8-ST8, seem to be spreading across different population groups in different regions of the country. Another important fact addressed in this review is the identification of the ST398-MRSA-IV/V clone and methicillin-susceptible S. aureus (MSSA) in healthy individuals from the community. Although susceptible to methicillin, the ST398 clone is associated with severe infections in humans and animals, denominated livestock-associated MRSA. It is therefore important to encourage assertive actions by all government sectors and by society, with a reassessment of current public health measures in light of the new perspectives arising from the scientific and epidemiological data on MRSA.

Community-genotype methicillin-resistant Staphylococcus aureus skin and soft tissue infections in Latin America: a systematic review

Background

Community-genotype methicillin-resistant Staphylococcus aureus (CG-MRSA) emerged in the 1990s as a global community pathogen primarily involved in skin and soft tissue infections (SSTIs) and pneumonia. To date, the CG-MRSA SSTI burden in Latin America (LA) has not been assessed.

Objective

The main objective of this study was to report the rate and genotypes of community-genotype methicillin-resistant Staphylococcus aureus (CG-MRSA) causing community-onset skin and soft tissue infections (CO-SSTIs) in LA over the last two decades. In addition, this research determined relevant data related to SSTIs due to CG-MRSA, including risk factors, other invasive diseases, and mortality.

Data sources

Relevant literature was searched and extracted from five major databases: Embase, PubMed, LILACS, SciELO, and Web of Science.

Methods

A systematic review was performed, and a narrative review was constructed.

Results

An analysis of 11 studies identified epidemiological data across LA, with Argentina presenting the highest percentage of SSTIs caused by CG-MRSA (88%). Other countries had rates of CG-MRSA infection ranging from 0 to 51%. Brazil had one of the lowest rates of CG-MRSA SSTI (4.5–25%). In Argentina, being younger than 50 years of age and having purulent lesions were predictive factors for CG-MRSA CO-SSTIs. In addition, the predominant genetic lineages in LA belonged to sequence types 8, 30, and 5 (ST8, ST30, and ST5).

Conclusion

There are significant regional differences in the rates of CG-MRSA causing CO-SSTIs. It is not possible to conclude whether or not CG-MRSA CO-SSTIs resulted in more severe SSTI presentations or in a higher mortality rate.

The History of Methicillin-Resistant Staphylococcus aureus in Brazil

Since the emergence of MRSA in the 1960s, a gradual increase in infections by resistant bacteria has been observed. Clinical manifestations may vary from brand to critical condition due to host risk factors, as well as pathogen virulence and resistance. The high adaptability and pathogenic profile of MRSA clones contributed to its spread in hospital and community settings. In Brazil, the first MRSA isolates were reported in the late 1980s, and since then different genetic profiles, such as the Brazilian epidemic clone (BEC) and other clones considered a pandemic, became endemic in the Brazilian population. Additionally, Brazil's MRSA clones were shown to be able to transfer genes involved in multidrug resistance and enhanced pathogenic properties. These events contributed to the rise of highly resistant and pathogenic MRSA. In this review, we present the main events which compose the history of MRSA in Brazil, including numbers and locations of isolation, as well as types of staphylococcal cassette chromosome mec (SCCmec) found in the Brazilian territory.

Incidence and characteristics of methicillin-resistant coagulase-negative Staphylococcus aureus in peritoneal dialysis-associated peritonitis in a single center using molecular methods

PURPOSE

Peritonitis is a serious complication of peritoneal dialysis and coagulase-negative Staphylococcus (CNS) is the most frequent cause of peritoneal dialysis (PD)-infections in many centers. This study aimed to investigate the molecular epidemiology of CNS isolated from PD-peritonitis in a Brazilian single center, focusing on the genetic determinants conferring methicillin resistance.

METHODS

Bacterial strains were isolated from peritoneal fluid of patients presenting PD-peritonitis, identified by phenotypic and molecular methods, and those identified as CNS were submitted to mecA detection, SCCmec, pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST).

RESULTS

Over the 18-year period of this study (1995-2011), a total of 878 peritonitis episodes were diagnosed in this unit, 115 were caused by coagulase-negative staphylococci of which 72 by Staphylococcus epidermidis. mecA gene was detected in 55 CNS (47.8%), more frequently on the more recent years. SCCmec type III was the most frequent cassette, followed by SCCmec type IV and SCCmec type II. A diverstity of pulsotypes was observed among the S. epidermidis isolates, but five clusters (based on the 80% cutoff) were identified. Diversified sequence types (ST02, ST05, ST06, ST09, ST23, ST59 and ST371) were detected.

CONCLUSIONS

Detection of SCCmec type III among coagulase-negative Staphylococcus underscores the role of hospital environments as potential source of methicillin-resistant Staphylococcus causing peritonitis in PD patients.

Occurrence of Methicillin-Resistant Staphylococcus aureus in Ready-to-Eat Raw Fish from Japanese Cuisine Restaurants in Salvador, Brazil

ABSTRACT

The presence of methicillin-resistant Staphylococcus aureus (MRSA) strains in food products is a major issue for food safety. The present study was conducted to evaluate the occurrence and antimicrobial resistance profile of S. aureus, focusing on MRSA isolates, in ready-to-eat sashimi from Japanese restaurants in Salvador, Brazil. A total of 127 sashimi samples were collected directly from the take-out service in 16 restaurants. The staphylococcal isolates were identified morphologically and biochemically with standard laboratory procedures. S. aureus isolates were tested with a disk diffusion assay against seven antibiotics, and the cefoxitin and oxacillin were used to identify MRSA strains. Isolates with the MRSA phenotype were confirmed with a PCR assay. S. aureus was found in 73% of the sashimi samples, including sashimi from tuna (75.5% of samples) and salmon (72.5% of samples). Among those positive samples, 37% were contaminated with MRSA strains, found among 38.8% of salmon sashimi and 34.0% of tuna sashimi. Penicillin resistance was the most common type of antimicrobial resistance, found in 65.5% of the sashimi samples, followed by resistance to tetracycline (22.5%), erythromycin (16.0%), and ciprofloxacin (3.2%). Only two S. aureus isolates collected from different fish samples and restaurants had presumed resistance to vancomycin. The high prevalence of S. aureus and MRSA in these sashimi samples indicates a potential risk for foodborne disease, especially MRSA, spreading in the community.

HIGHLIGHTS

Frequency of Community-acquired Methicillin-resistant Staphylococcus aureus in Pediatric Population in a General Hospital in São Paulo, Brazil, Over 5 Years

We retrospectively evaluated the frequency of community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) infections in children at a general hospital in São Paulo, Brazil, from 2011 to 2015. Of 64 patients with confirmed S. aureus infection, 11 (17.2%) had CA-MRSA. CA-MRSA infections in Brazil, and in particular those with a severe presentation, should not be overlooked.

Monitoring and Molecular Characterization of Staphylococcus aureus Isolated from Chronic Wounds

OBJECTIVE

Researchers analyzed chronic wounds treated with 2% hydrogel to determine whether the presence of methicillin-resistant Staphylococcus aureus (MRSA) is related to the presence of clinical signs of infection.

METHODS

Thirty-five patients were recruited for this descriptive study using a quantitative approach. Staphylococcus aureus was identified by matrix-assisted laser desorption ionization time-of-flight mass spectrometry. Antibiotic susceptibility was determined using a disk diffusion test according to Clinical and Laboratory Standards Institute standards. Polymerase chain reaction, pulsed-field gel electrophoresis, and multilocus sequence typing were performed. Statistical analyses were performed using Spearman correlation coefficients for the variables MRSA and clinical signs of infection.

MAIN OUTCOME MEASURES

The identification of MRSA or methicillin-sensitive S aureus (MSSA), presence or absence of an infection in the wound, and molecular characterization of bacteria were measured.

MAIN RESULTS

Of the 35 patients analyzed, 8 (22.9%) were classified as having an infection in their wounds. Spearman ρ indicated a strong positive correlation between the increase in the number of clinical signs of infection and MSSA (P =.84), but only a moderate positive correlation with MRSA (P =.60). The S aureus clonal pattern was unique for each of the major bacteria isolated. Global MRSA sequence-type clones (ST-1 and ST-72) were detected in 2 patients.

CONCLUSIONS

Compared with those colonized by MSSA, chronic wounds colonized by MRSA did not display a strong correlation with the presence of a greater number of clinical signs of infection.

Molecular epidemiology of methicillin-resistant Staphylococcus aureus in the Brazilian primary health care system

OBJECTIVE

To evaluate the molecular epidemiology and to georeference Staphylococcus aureus isolated from wounds and nares of patients seen at Basic Health Units (BHUs) of a Brazilian city.

METHODS

Observational, cross-sectional study conducted from 2010 to 2013. A total of 119 S. aureus strains isolated from the wounds and nares of 88 patients were studied. The isolates were characterised by identifying virulence genes encoding enterotoxins A-E, haemolysins α, β and δ, exfoliatins A, B and D, biofilm production, Panton-Valentine Leukocidin and toxic shock syndrome toxin 1, and by pulsed-field gel electrophoresis (PFGE), multilocus sequence and spa typing.

RESULTS

Eighteen methicillin-resistant Staphylococcus aureus (MRSA) (6 SCCmec type II and 12 SCCmec type IV) and 101 (85%) MSSA were identified. PFGE typing resulted in the formation of eight clusters, with STs 1, 5, 8, 30, 188, 1176 and 1635 and spa type t002 being the predominant types among MSSA. The 18 MRSA belonged to STs 5, 8 and 1176 and spa types t002 and t062.

CONCLUSION

The results demonstrate widespread dissemination of MSSA and MRSA clones carrying haemolysin, biofilm and toxin genes. Kernel density estimation revealed the highest density of S. aureus in the 4, 5 and 8 BHUs.

Seek and Find! PCR analyses of skin infections in West-European travelers returning from abroad with an eschar

BACKGROUND

Skin infections are among the leading causes of diseases in travelers. Diagnosing pathogens could be difficult.

METHOD

We applied molecular assays for the diagnostic of a large collection of skin biopsies and swabs from travelers with suspected skin infections. All samples were tested by qPCR for Coxiella burnetti, Bartonella sp., Rickettsia sp., Borrelia sp., Ehrlichia sp., Tropheryma whipplei, Francisella tularensis, Mycobacteria sp., Staphylococcus aureus, Streptococcus pyogenes, Leishmania spp., Ortho poxvirus and Para poxvirus and then screened for the presence of bacteria by PCR amplification and sequencing, targeting the 16S rRNA gene.

RESULTS

From January 2009 to January 2017, 100 international travelers presenting with a suspected skin infection were enrolled. We detected 51 patients with an identified pathogen on skin samples. Travelers presenting with eschars were more likely to have a positive PCR sample (n = 44/76, 57.9%) compared to other patients (n = 7/24, 29.2%). Spotted fever group Rickettsia (n = 28) was the most frequently detected pathogens (19 R. africae, 6 R. conorii, 3 R. mongolitimonae); S. aureus were detected in 11 patients; S. pyogenes in 3; Leishmania sp.; M. leprae and B. henselae in 1 patient, respectively.

CONCLUSION

By targeting the most commonly encountered causative agents of travel-related skin infections, our strategy provides a sensitive and rapid diagnostic method.

Epidemiology and molecular characteristics of methicillin-resistantStaphylococcus aureus from skin and soft tissue infections in Shiraz, Iran

BACKGROUND/AIM

Panton-Valentine leukocidin (PVL)-positive methicillin-resistant Staphylococcus aureus (MRSA) infections are increasing in some regions of Iran. The aim of the current study was to assess the epidemiology and molecular characteristics of S. aureus isolated from patients with skin infections in Shiraz, Iran.

MATERIALS AND METHODS

Swab samples were obtained from patients admitted to the skin and burn units of hospitals. The medical records of each patient were collected via questionnaire. All staphylococcal isolates were collected and examined by conventional methods for detecting S. aureus strains. PCR was used to detect S. aureus harboring the mecA and pvl genes.

RESULTS

Out of 243 staphylococcal isolates, 55 (22.6%) S. aureus and 91 (37.4%) S. epidermidis were detected. Of the 45 patients, 21 (46.7%) were S. aureus carriers. The mecA gene was identified in 60% of S. aureus isolates, and the rest were sensitive to methicillin. Of the S. aureus isolates, 54.5% were positive for the pvl gene.

CONCLUSION

This study revealed a high prevalence of PVL-positive MRSA strains in the evaluated hospitals. Thus, early diagnosis of infections caused by this pathogen seems to be necessary by intake screening allowing for proper treatment, especially in high-risk patients and in order to prevent the spread of infection.

Toxigenic profile of methicillin-sensitive and resistant Staphylococcus aureus isolated from special groups

Background

Staphylococcus aureus is characterized by its pathogenicity and high prevalence, causing disease in both healthy and immunocompromised individuals due to its easy dissemination. This fact is aggravated by the widespread dissemination of S. aureus carrying toxigenic genes. The objective of this study was to determine the toxigenic profile of methicillin-sensitive S. aureus (MSSA) and methicillin-resistant S. aureus (MRSA) in patients with purulent skin and/or soft tissue infections seen at the Dermatology Department of the University Hospital of the Botucatu Medical School, asymptomatic adults older than 60 years living in nursing homes, and prison inmates of the Avaré Detention Center.

Methods

PCR was used for the detection of the mecA gene, enterotoxin genes (sea, seb, and sec), exfoliative toxins A and B (eta and etb), toxic shock syndrome toxin 1 (tst), panton–valentine leukocidin (lukS-PV and lukF-PV), and alpha- and delta-hemolysins or cytotoxins (hla and hld).

Results

The results showed a significant prevalence of toxigenic genes among S. aureus isolates from asymptomatic individuals, with the observation of a higher prevalence of cytotoxin genes. However, the panton–valentine leukocidin gene was only detected in MSSA isolated from patients with skin infections and the tst gene was exclusively found in MSSA isolated from prison inmates.

Conclusions

The present study demonstrated a significant prevalence of toxigenic genes in MSSA and MRSA strains isolated from asymptomatic S. aureus carriers. There was a higher prevalence of cytotoxin genes.