Non-multiresistant and multiresistant methicillin-resistant Staphylococcus aureus in community-acquired infections

International comparison of guidelines for management of impetigo: a systematic review

BACKGROUND

Impetigo is a common superficial skin infection that affects people worldwide and is usually treated with antibiotics; therefore, its management has implications for global antibiotic stewardship.

OBJECTIVE

This systematic review and narrative synthesis compares and contrasts international impetigo management guidelines.

METHODS

Guidelines for treatment of impetigo that were produced by a national authority; available to primary care physicians; and published since 2008 were included. Following a comprehensive search strategy, data extraction from eligible studies was performed independently in duplicate. Details of antiseptic and antibiotic treatment; methicillin-resistant Staphylococcus aureus treatment; and conservative management and preventative measures were tabulated and analysed descriptively.

RESULTS

Fifty-one guidelines were included from 42 different countries. All guidelines recommended systemic antibiotics, 78% of these only for widespread lesions or failure of topical antibiotic treatment. The first-line systemic antibiotic treatment was restricted to narrow-spectrum options in 21 (41%) whilst 7 (14%) recommended only broad-spectrum antibiotics first-line. Thirty-four (67%) guidelines included recommendations for topical antibiotic use. Twenty guidelines (39%) did not mention antiseptic treatment for impetigo. Guidelines did not always provide clear indications for different treatment options.

CONCLUSIONS

Despite potentially equal efficacy to systemic antibiotics, only two-thirds of guidelines include topical antibiotic options. Many fail to include recommendations for non-antibiotic treatments such as antiseptics, preventative measures and conservative management, despite potential for antibiotic-sparing. Provision of clear definitions of disease severity and indications for treatment would enhance the ability of clinicians to adhere to recommendations.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42018117770.

Antibiotic stewardship in skin infections: a cross-sectional analysis of early-career GP's management of impetigo

OBJECTIVE

To establish the prevalence and associations of systemic antibiotic prescription for impetigo by early-career general practitioners (GPs) (GP registrars in their first 18 months in general practice).

DESIGN

A cross-sectional analysis of data from the Registrar Clinical Encounters in Training (ReCEnT) study.

SETTING

ReCEnT is an ongoing multisite cohort study of Australian registrars' in-consultation clinical practice across five Australian states.

PARTICIPANTS

Registrars participating in ReCEnT from 2010 to 2017.

OUTCOME MEASURES

Management of impetigo with systemic antibiotics.

RESULTS

1741 registrars (response rate 96%) provided data from 384 731 problems identified in 246 434 consultations. Impetigo, on first presentation or follow-up, was managed in 930 (0.38%, 95% CI 0.35 to 0.40) consultations and comprised 0.24% (95% CI 0.23 to 0.26) of problems. 683 patients presented with a new diagnosis of impetigo of which 38/683 (5.6%) were not prescribed antibiotics; 239/683 (35.0%) were prescribed solely topical antibiotics; 306/683 (44.8%) solely systemic antibiotics and 100/683 (14.6%) both systemic and topical antibiotics. The most common systemic antibiotic prescribed was cephalexin (53.5%). Variables independently associated with prescription of systemic antibiotics were an inner regional (compared with major city) location (OR 1.82, 95% CI 1.06 to 3.13; p=0.028), seeking in-consultation information or advice (OR 2.17, 95% CI 1.47 to 3.23; p<0.001) and ordering pathology (OR 2.13, 95% CI 1.37 to 3.33; p=0.01).

CONCLUSIONS

Australian early-career GPs prescribe systemic antibiotics (the majority broad-spectrum) for a high proportion of initial impetigo presentations. Impetigo guidelines should clearly specify criteria for systemic antibiotic prescription and individual antibiotic choice. The role of non-antibiotic management and topical antiseptics needs to be explored further.

Antibiotic Resistance in Pacific Island Countries and Territories: A Systematic Scoping Review

Several studies have investigated antimicrobial resistance in low- and middle-income countries, but to date little attention has been paid to the Pacific Islands Countries and Territories (PICTs). This study aims to review the literature on antibiotic resistance (ABR) in healthcare settings in PICTs to inform further research and future policy development for the region. Following the PRISMA-ScR checklist health databases and grey literature sources were searched. Three reviewers independently screened the literature for inclusion, data was extracted using a charting tool and the results were described and synthesised. Sixty-five studies about ABR in PICTs were identified and these are primarily about New Caledonia, Fiji and Papua New Guinea. Ten PICTs contributed the remaining 21 studies and nine PICTs were not represented. The predominant gram-positive pathogen reported was community-acquired methicillin resistant S. aureus and the rates of resistance ranged widely (>50% to <20%). Resistance reported in gram-negative pathogens was mainly associated with healthcare-associated infections (HCAIs). Extended spectrum beta-lactamase (ESBL) producing K. pneumoniae isolates were reported in New Caledonia (3.4%) and Fiji (22%) and carbapenem resistant A. baumannii (CR-ab) isolates in the French Territories (24.8%). ABR is a problem in the PICTs, but the epidemiology requires further characterisation. Action on strengthening surveillance in PICTs needs to be prioritised so strategies to contain ABR can be fully realised.

Emerging variants of methicillin-resistant Staphylococcus aureus genotypes in Kuwait hospitals

Background

Frequent changes in the epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) occurring worldwide demand regular surveillance to study their composition and distribution in healthcare facilities. We investigated the genotypic characteristics of MRSA obtained in Kuwait hospitals to better understand their clonal distribution.

Materials and methods

A total of 1,327 MRSA isolates obtained from clinical samples in 13 Kuwait hospitals from 1 January to 31 December 2016 were investigated using antibiogram, SCCmec typing, spa typing and DNA microarray.

Results

The isolates belonged to six SCCmec types with the majority belonging to type IV (658; 49.5%) and type V (355; 26.7%). Two hundred and sixty-one spa types were identified with spa types t688, t304, t860, t127, t044, t311, t002, t223, t267, t019, t3841, t005, t084, t852, and t657 constituting 51.0% (n = 677) of the isolates. Among the 1,327 MRSA isolates, 102 (7.68%) isolates were identified as novel variants of internationally recognized MRSA clones. These 102 isolates were investigated further and belonged to 14 clonal complexes (CCs) with CC361 (32; 32.3%), CC30 (15; 14.7%), CC22 (13; 12.7%) and CC1 (11, 10.7%) as the dominant CCs. Eighty-one (79.4%) of the novel isolates harbored SCCmec IV or V+fusC composite genetic elements. Four isolates (3.9%) harbored unusual combinations of ccr and mec complexes comprising of CC6-MRSA [IV+fusC+ccrC], CC97-MRSA [V/V_T+fusC+ccrAB2], CC121-MRSA [V/V_T+fusC+ccrB4] and CC1-MRSA-pseudoSCCmec [class B mec+fusc+ccrAB1]. Forty-six (45.1%) of these isolates were positive for PVL and 89 (87.2%) were resistant to fusidic acid mediated by fusC.

Conclusions

The study showed the emergence of novel variants of previously recognized MRSA genotypes with unusual genetic characteristics including high prevalence of PVL and fusidic acid resistance in Kuwait hospitals. This has added to the dynamic lists of known variations in MRSA genomes which can impose serious challenges for infection control and treatment of MRSA infections.

Effects of trimethoprim on life history parameters, oxidative stress, and the expression of cytochrome P450 genes in the copepod Tigriopus japonicus

Trimethoprim (TMP) is an antibiotic that has been detected in various environments including marine habitats; however, the toxic effects of TMP are poorly understood in non-target marine organisms. In this study, the effects of TMP on mortality, development, reproduction, intracellular reactive oxygen species (ROS) levels, and transcription levels of antioxidant and xenobiotic detoxification-related enzyme genes were investigated in the copepod Tigriopus japonicus. The TMP half lethal dose at 48 h (LC50-48 h) in nauplius and TMP LC50-96 h in adult T. japonicus copepods was determined as 156 mg/L and 200 mg/L, respectively. In TMP-exposed T. japonicus, delayed developmental time and impaired reproduction were observed as harmful effects on the life history parameters. Increased ROS levels were also shown in response to TMP exposure at the highest concentration (100 mg/L TMP) and the expression of antioxidant- (e.g. GST-kappa, GST-sigma) and xenobiotic detoxification (e.g. CYPs)-related genes were upregulated in a time and/or dose-dependent manner in response to TMP. Particularly, significant upregulation of three CYP genes (Tj-CYP3024A2, Tj-CYP3024A3 and Tj-CYP3027C2) were examined, suggesting that these CYP genes are likely playing an important role in the TMP detoxification metabolism in T. japonicus. In summary, we found that TMP induced oxidative stress via the transcriptional regulation of antioxidant- and xenobiotic detoxification-related genes, leading to changes in life history parameters such as developmental delay and reproduction impairment. Three Tj-CYP genes (Tj-CYP3024A2, Tj-CYP3024A3 and Tj-CYP3027C2) could be useful as potential T. japonicus biomarkers in response to antibiotics.

High prevalence of Panton-Valentine leukocidin (PVL) genes in nosocomial-acquired Staphylococcus aureus isolated from tertiary care hospitals in Nepal

Methicillin-resistant Staphylococcus aureus (MRSA) carrying the important virulence determinant, Panton-Valentine leukocidin (PVL), is an emerging infectious pathogen associated with skin and soft tissue infections as well as life-threatening invasive diseases. In carrying out the first PVL prevalence study in Nepal, we screened 73 nosocomial isolates of S. aureus from 2 tertiary care Nepali hospitals and obtained an overall PVL-positivity rate of 35.6% among the hospital isolates: 26.1% of MRSA and 51.9% of methicillin sensitive S. aureus (MSSA) isolates were found to be positive for the PVL genes. PVL prevalence was not associated with a specific (i) infection site, (ii) age group, or (iii) hospital of origin. It was found to be positively associated with heterogeneous MRSA (73.3%) compared to homogeneous MRSA (3.2%) and MSSA (51.9%); negatively associated with multiresistant MRSA (22%) compared to nonmultiresistant MRSA (60%) and MSSA (51.9%); and positively associated with macrolide-streptogramin B resistance (93.8%) compared to macrolide-lincosamide-streptogramin B resistance (0%) and no-resistance (45.8%) types. Macrolide-streptogramin B resistance was confirmed by the presence of msr(A) gene. Restriction pattern analyses provided evidence to support the circulation of a limited number of clones of PVL-positive MRSA, arguing for the adaptability of these isolates to a hospital setting.

Community-acquired methicillin-resistant Staphylococcus aureus: the new face of an old foe?

The burden of infections caused by community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) is increasing among different patient populations globally. As CA-MRSA has become established in healthcare facilities, the range of infections caused by them has also increased. Molecular characterization of CA-MRSA isolates obtained from different centers has revealed significant diversity in their genetic backgrounds. Although many CA-MRSA strains are still susceptible to non-β-lactam antibiotics, multiresistance to non-β-lactam agents has emerged in some clones, posing substantial problems for empirical and directed therapy of infections caused by these strains. Some CA-MRSA clones have acquired the capacity to spread locally and internationally. CA-MRSA belonging to ST80-MRSA-IV and ST30-MRSA-IV appear to be the dominant clones in the countries of the Gulf Cooperation Council (GCC). The emergence of pandemic CA-MRSA clones not only limits therapeutic options but also presents significant challenges for infection control. Continued monitoring of global epidemiology and emerging drug resistance data is critical for the effective management of these infections.

Sensitivy to antibiotics in strains of S. aureus isolated from cow´s milk

Strains of S. aureus were isolated from individual milk samples of 500 lacting cows from different areas in Slovakia (PH 1 - Košice region, 300 samples; PH 2 - Žilina region, 200 samples). The statistical significance between both dairy farms included in the experiment in the presence of genus Staphylococcus isolated on Baird-Parker agar from milk samples was p < 0,0001(***) . Totally, 122 milk samples were positive for the presence of Staphylococcus aureus (83 Košice regions, 52 Žilina regions). All 122 isolates of S. aureus were sensitive for the methicilin as detected by interpretative criteria developed by NCCLS (2002). For 122 S. aureus isolates, we compared antibiotic susceptibility results determined by the standardized agar diffusion assay with the PCR assay for the detection of antibiotic resistance mecA gene. For all isolates, we found a correlation between the results of the PCR and those of classical resistance testing. The obtained results were confirmed by PCR analysis, according to which, any of our tested isolate of S. aureus from all 122 individual milk samples from both experimental dairy farms were not positive for the presence of mecA gene coding  the methicilin resistance.

Community-associated methicillin-resistant Staphylococcus aureus: epidemiology and clinical consequences of an emerging epidemic

Staphylococcus aureus is an important cause of skin and soft-tissue infections (SSTIs), endovascular infections, pneumonia, septic arthritis, endocarditis, osteomyelitis, foreign-body infections, and sepsis. Methicillin-resistant S. aureus (MRSA) isolates were once confined largely to hospitals, other health care environments, and patients frequenting these facilities. Since the mid-1990s, however, there has been an explosion in the number of MRSA infections reported in populations lacking risk factors for exposure to the health care system. This increase in the incidence of MRSA infection has been associated with the recognition of new MRSA clones known as community-associated MRSA (CA-MRSA). CA-MRSA strains differ from the older, health care-associated MRSA strains; they infect a different group of patients, they cause different clinical syndromes, they differ in antimicrobial susceptibility patterns, they spread rapidly among healthy people in the community, and they frequently cause infections in health care environments as well. This review details what is known about the epidemiology of CA-MRSA strains and the clinical spectrum of infectious syndromes associated with them that ranges from a commensal state to severe, overwhelming infection. It also addresses the therapy of these infections and strategies for their prevention.

Epidemiology of non-multiresistant methicillin-resistant Staphylococcus aureus infection in Queensland, Australia: associations with indigenous populations and Panton-Valentine leukocidin

The purpose of this study was to determine the extent of the spread of epidemic clones of non-multiresistant methicillin-resistant Staphylococcus aureus (nmMRSA) and the epidemiology of resultant infections throughout the state of Queensland. We collected a sample of clinical isolates of nmMRSA from laboratories serving public hospitals and clinics throughout the state. Three hundred isolates were typed and tested for the presence of Panton-Valentine leukocidin (PVL) genes and demographic and clinical data were collected from associated cases. Fifteen percent of S. aureus isolates were nmMRSA and 69% of these belonged to PVL-positive clones, predominantly ST93 and CC30. Low numbers of USA300- and USA400-like isolates were also present. Infections due to PVL-positive strains were much less frequently acquired in hospital (3.4%) than those due to PVL-negative nmMRSA (23.7%). Thirty-seven percent of cases were in indigenous people who make up only 3.6% of the general population. The proportion of cases with PVL-positive, but non-negative isolates decreased progressively with age, suggesting that immunity to PVL might be an important determinant of protection. nmMRSA strains are present throughout Queensland and cause infections in both community and healthcare settings.

Pathogenesis of methicillin-resistant Staphylococcus aureus infection

Staphylococcus aureus is a versatile pathogen capable of causing a wide range of human diseases. However, the role of different virulence factors in the development of staphylococcal infections remains incompletely understood. Some clonal types are well equipped to cause disease across the globe, whereas others are facile at causing disease among community members. In this review, general aspects of staphylococcal pathogenesis are addressed, with emphasis on methicillin-resistant strains. Although methicillin-resistant S. aureus (MRSA) strains are not necessarily more virulent than methicillin-sensitive S. aureus strains, some MRSA strains contain factors or genetic backgrounds that may enhance their virulence or may enable them to cause particular clinical syndromes. We examine these pathogenic factors.

Clinical features, epidemiology, antimicrobial resistance, and exotoxin genes (including that of Panton-Valentine leukocidin) of gentamicin-susceptible methicillin-resistant Staphylococcus aureus (GS-MRSA) isolated at a paediatric teaching hospital in New South Wales, Australia

AIMS

To describe the epidemiological, clinical, and laboratory features of gentamicin-susceptible methicillin-resistant Staphylococcus aureus (GS-MRSA) seen at a paediatric teaching hospital.

METHODS

Patients from whom GS-MRSA was isolated between 1 January 2001 and 31 December 2002 were enrolled. Retrospective chart review was performed. Susceptibility testing was performed with the Vitek2 system; PCR confirmed methicillin resistance. Phage typing and pulsed field gel electrophoresis (PFGE) was performed (utilising MLST/SCCmec-defined control strains). PCR detection of tst, luk-PV, and entA-entE was performed.

RESULTS

Eighty-five per cent of all Staphylococcus aureus isolates during the study period were methicillin-sensitive, and 15% were MRSA (9% GS-MRSA, 6% gentamicin resistant-MRSA). 100 GS-MRSA infections in 98 children were identified: 59 cases of skin/soft tissue, four bone and joint, four surgical site infections, three pneumonia, eight other types, and 22 represented colonisation. Ninety-nine isolates were non-multidrug resistant, but 17 strains were resistant to erythromycin, 7 to tetracyclines, 12 to ciprofloxacin, 11 to fusidic acid, 1 each to rifampicin and mupirocin. 44 isolates were Oceania strain (ST30-MRSA-IV), 20 were Queensland strain (ST93-MRSA-IV), ten were UK EMRSA-15 (ST22-MRSA-IV), eight were WA MRSA-1 (ST1-MRSA-IV), two were WA MRSA-5 (ST8-MRSA-IV), one was WA MRSA-2 (ST78slv-MRSA-IV), one was WA MRSA-15 (ST59-MRSA-IV), and the remainder were sporadics. Twenty patients were Pacific Islanders, of whom 12 had the Oceania strain; ten were Aboriginal, of whom eight had the Queensland strain. Sixty-eight isolates possessed luk-PV, including all Queensland strains and 91% of Oceania strains. Enterotoxin genes were detected in 25% of the isolates, and tst was detected in four isolates.

CONCLUSIONS

GS-MRSA is a significant paediatric problem in New South Wales: two minority groups are over-represented, multiple epidemic strains were detected, most community strains possess luk-PV, and many isolates are multidrug resistant.

Adult methicillin-resistant Staphylococcus aureus bacteremia in Taiwan: clinical significance of non–multi-resistant antibiogram and Panton–Valentine leukocidin gene

It is poorly defined whether or not adult patients with methicillin-resistant Staphylococcus aureus (MRSA) bacteremia with a non-multi-resistant antibiogram phenotype and Panton-Valentine leukocidin (PVL) gene carriage have different clinical syndromes. Clinical characteristics of 95 adult patients of MRSA bacteremia, with isolates that were non-multi-resistant to non-beta-lactam, were compared with a contemporaneous multiresistant group. Independent risk factors other than community-associated MRSA bacteremia patients associated with recovery of non-multi-resistant MRSA isolates by multivariate analysis included deep-seated infection and catheter insertion site infection. Older age, intensive care unit-onset bacteremia, and postoperative infection were negative independent risk factors associated with non-multi-resistant MRSA isolates. Most of the 60 recoverable non-multi-resistant MRSA isolates belonged to multilocus sequence type 59, and all isolates belonged to staphylococcal chromosomal cassette mec (SCCmec) element type IV or type V. Most PVL-positive MRSA isolates belonged to SCCmec V. PVL-positive CA-MRSA isolates could cause more deep-seated infections in patients presented with non-multi-resistant MRSA bacteremia.

Detection and characterization of international community-acquired infections by methicillin-resistant Staphylococcus aureus clones in Rio de Janeiro and Porto Alegre cities causing both community- and hospital-associated diseases

Community-acquired infections by methicillin-resistant Staphylococcus aureus (CA-MRSA) in the absence of classic risk factors for MRSA diseases have been reported in different continents. In the article presented here, using molecular typing methods as pulsed-field gel electrophoresis, staphylococcal cassette chromosome mec typing, and multilocus sequence typing, we characterized CA-MRSA isolates from Rio Janeiro and Porto Alegre. The results indicated the presence of international CA-MRSA clones in these 2 Brazilian cities. In addition, Panton-Valentine leukocidin and a number of staphylococcal enterotoxin encoding genes were accessed in these MRSA isolates by polymerase chain reaction detection.

Community-acquired methicillin-resistant Staphylococcus aureus skin infections: a review of epidemiology, clinical features, management, and prevention

Community-acquired methicillin-resistant Staphylococcus aureus (CAMRSA) infection is a global problem of epidemic proportions. Many of the patients who develop CAMRSA skin lesions do not have infection-associated risk factors. Abscess, abscess with accompanying cellulitis, and cellulitis are the most common presentations of cutaneous CAMRSA infection; occasionally, these CARMSA-related lesions are misinterpreted as spider or insect bites. Other manifestations of cutaneous CAMRSA infection include impetigo, folliculitis, and acute paronychia. The management of CAMRSA skin infection includes incision and drainage, systemic antimicrobial therapy, and adjuvant topical antibacterial treatment. In addition, at the initial visit, bacterial culture of the lesion should be considered. Direct skin-to-skin contact, damage to the skin surface, sharing of personal items, and a humid environment are potential mechanisms for the acquisition and transmission of cutaneous CAMRSA infection. Measures that strive to eliminate these causes are useful for preventing the spread of CAMRSA skin infection.

Methicillin-resistant Staphylococcus aureus caruncle abscess

A 60-year-old woman under treatment for a left lower eyelid abscess developed a right caruncle abscess. Methicillin-resistant Staphylococcus aureus (MRSA) was identified in cultures performed on both lesions. Treatment consisted of oral ciprofloxacin and moxifloxacin drops. There was resolution of both lesions with incision and drainage, and antibiotic therapy. MRSA is a pathogen that can be readily isolated from the caruncle. The authors are unaware of previous reported cases of a MRSA caruncle abscess.

Community-associated methicillin-resistant Staphylococcus aureus hand infections in an urban setting

PURPOSE

The prevalence of methicillin-resistant Staphylococcus aureus (MRSA) infection appears to be increasing. The purpose of this study was to determine prospectively the incidence of MRSA in community-associated hand infections in an urban hospital.

METHODS

Sixty-one patients presented to our institution over a 9-month period with community-acquired hand infections that were evaluated and treated by the hand service. The specimens obtained during the initial evaluation and treatment were cultured and subjected to antibiotic susceptibility testing. Four nosocomial infections and 5 fight bites were excluded.

RESULTS

Of the remaining 52 patients, 38 (73.1%) were MRSA positive.

CONCLUSIONS

The rate of community-associated MRSA hand infections in an urban setting is higher than previously suspected. This should be taken into account when managing seemingly routine hand infections given that the treatment options are different for MRSA infections.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

Non-multiresistant methicillin-resistant Staphylococcus aureus bacteraemia in Sydney, Australia: emergence of EMRSA-15, Oceania, Queensland and Western Australian MRSA strains

AIMS

To describe clinical features and molecular epidemiology of non-multiresistant methicillin-resistant Staphylococcus aureus (MRSA) bacteraemia.

METHODS

Patients with non-multiresistant MRSA isolated from blood at South Western Area Pathology Service from 1 January 1999 to 31 December 2001 were enrolled. Pulsed field gel electrophoresis, phage typing, and (selected instances) multilocus sequence and staphylococcal cassette chromosome typing was performed. PCR was used to detect Panton-Valentine leukocidin (PVL), toxic shock syndrome toxin-1 (TSST-1), and enterotoxin genes.

RESULTS

Sixteen patients were detected: eight with UK EMRSA-15 (ST22-MRSA-IV), three with Oceania (South-West Pacific/Western Samoan phage pattern) (ST30-MRSA-IV), two with WA MRSA-5 (ST8-MRSA-IV), and one each with WA MRSA-1 (ST1-MRSA-IV), Queensland strain (ST93-MRSA-IV), and WA MRSA-15 (ST59-MRSA-IV). Prior hospital admissions occurred with six of the eight patients with UK EMRSA-15, none of the three with Oceania, and three of the five with other strains. Thirteen of 16 patients had underlying disease. Three of the three patients with Oceania strain bacteraemia were Polynesians; 11 of 13 of the others were Caucasians. PVL genes were detected in four of 16 isolates (all Oceania and Queensland strains). entC was detected in two EMRSA-15 strains; entA in one Oceania, two WA MRSA-5 and the WA MRSA-1 strain, with entA and entB in the WA MRSA-15 strain. tst was not detected.

CONCLUSIONS

Multiple epidemic strains cause non-multiresistant MRSA bacteraemia. Most patients had risk factors. Oceania and Queensland strains possess the PVL gene.

Methicillin‐resistant Staphylococcus aureus in the Australian community: an evolving epidemic

OBJECTIVE

To describe antimicrobial resistance and molecular epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) isolated in community settings in Australia.

DESIGN AND SETTING

Survey of S. aureus isolates collected prospectively Australia-wide between July 2004 and February 2005; results were compared with those of similar surveys conducted in 2000 and 2002.

MAIN OUTCOME MEASURES

Up to 100 consecutive, unique clinical isolates of S. aureus from outpatient settings were collected at each of 22 teaching hospital and five private laboratories from cities in all Australian states and territories. They were characterised by antimicrobial susceptibilities (by agar dilution methods), coagulase gene typing, pulsed-field gel electrophoresis, multilocus sequence typing, SCCmec typing and polymerase chain reaction tests for Panton-Valentine leukocidin (PVL) gene.

RESULTS

2652 S. aureus isolates were collected, of which 395 (14.9%) were MRSA. The number of community-associated MRSA (CA-MRSA) isolates rose from 4.7% (118/2498) of S. aureus isolates in 2000 to 7.3% (194/2652) in 2004 (P = 0.001). Of the three major CA-MRSA strains, WA-1 constituted 45/257 (18%) of MRSA in 2000 and 64/395 (16%) in 2004 (P = 0.89), while the Queensland (QLD) strain increased from 13/257 (5%) to 58/395 (15%) (P = 0.0004), and the south-west Pacific (SWP) strain decreased from 33/257 (13%) to 26/395 (7%) (P = 0.01). PVL genes were detected in 90/195 (46%) of CA-MRSA strains, including 5/64 (8%) of WA-1, 56/58 (97%) of QLD, and 25/26 (96%) of SWP strains. Among health care-associated MRSA strains, all AUS-2 and AUS-3 isolates were multidrug-resistant, and UK EMRSA-15 isolates were resistant to ciprofloxacin and erythromycin (50%) or to ciprofloxacin alone (44%). Almost all (98%) of CA-MRSA strains were non-multiresistant.

CONCLUSIONS

Community-onset MRSA continues to spread throughout Australia. The hypervirulence determinant PVL is often found in two of the most common CA-MRSA strains. The rapid changes in prevalence emphasise the importance of ongoing surveillance.

Methicillin-resistant Staphylococcus aureus clones, Western Australia

The emergence of multiple multidrug-resistant Panton-Valentine leukocidin–positive MRSA clones in the community is a major public health concern.

Community-associated methicillin-resistant Staphylococcus aureus (MRSA) was first reported in Western Australia in the early 1990s from indigenous peoples living in remote areas. Although a statewide policy of screening all hospital patients and staff who have lived outside the state for MRSA has prevented the establishment of multidrug-resistant epidemic MRSA, the policy has not prevented SCCmec type IV and type V MRSA clones from becoming established. Of the 4,099 MRSA isolates analyzed (referred to the Gram-positive Bacteria Typing and Research Unit) from July 2003 to December 2004, 77.5% were community-associated MRSA (CA-MRSA). Using multilocus sequence/staphylococcal chromosome cassette mec typing, 22 CA-MRSA clones were characterized. Of these isolates, 55.5% were resistant to >1 non–β-lactam antimicrobial drug. Five Panton-Valentine leukocidin (PVL)–positive CA-MRSA clones were identified. The emergence of multidrug-resistant CA-MRSA clones and the detection of PVL toxin genes in clones previously reported as PVL negative is a major public health concern.

Chronic osteomyelitis in children: Shriners Hospital Honolulu experience

Chronic osteomyelitis incidence and severity in 55 hospitalized Pacific Island children between 1990 and 2002 were compared with the expected incidence and reports in the literature. Of these 55 cases, 87% were from Polynesia/Micronesia. The average length of hospital stay was 104 days. Staphylococcus aureus was cultured in 64% of the cases with 43% of those being methicillin resistant S. aureus. A total of 111 bones were involved. Average antibiotic treatment was 135 days. Each case required an average of 1.3 irrigations/debridements and 45% required a sequestrectomy. Ninety-two percent had elevated erythrocyte sedimentation rate on admission. Sixty-nine percent of the cases involved metaphyseal, diaphyseal and epiphyseal segments of the bone and 29% were multifocal. Results indicate that Pacific Island children have a higher incidence and increased severity of osteomyelitis when compared with non-Pacific Island children in the literature, requiring a high suspicion for multifocal osteomyelitis, extensive bone involvement, S. aureus positive cultures and a longer period of antibiotic treatment.

Acute hematogenous osteomyelitis in children: recognition and management

Acute hematogenous osteomyelitis is most common in children and has the potential to cause life-long musculoskeletal deformities. Most cases are caused by Staphylococcus aureus. Haemophilus influenzae type b (Hib) is now rare in countries that routinely use the Hib vaccine. Although magnetic resonance imaging is the preferred modality in localized disease, scintigraphy is often preferred as the first line of investigation because it helps to clarify the location of infection and exclude the presence of multifocal disease. Where the presentation is typical, there is no underlying disease, there is a low prevalence of community-acquired methicillin-resistant S. aureus (CA-MRSA), and there is a good response to antibacterial therapy, a diagnostic bone aspirate or biopsy is not necessary. The first-line antibacterial choice in most circumstances is a beta-lactamase-resistant penicillin. If CA-MRSA is suspected, the first-line options include clindamycin, the addition of an aminoglycoside or, rarely, vancomycin. In most patients, the total duration of therapy can be substantially shorter than the traditional 6 weeks, and oral therapy can be commenced after a brief course of intravenous antibacterials. We recommend 3 days of intravenous therapy followed by 3 weeks of high-dose oral antibacterials, provided there is no underlying illness, the presentation is typical and acute, and there has been a good response to treatment initially. Any deviation from this requires more intensive confirmation of the diagnosis (with imaging and/or biopsy or aspiration), and prolongation of intravenous therapy and total duration of treatment. Close monitoring and follow-up for at least 2 years are advised to detect complications.

Cutaneous Community-acquired Methicillin-resistant Staphylococcus aureus Infection in Participants of Athletic Activities

OBJECTIVES

Cutaneous community-acquired methicillin-resistant Staphylococcus aureus (CAMRSA) has been identified in otherwise healthy individuals either with or without methicillin-resistant S. aureus (MRSA)-associated risk factors who participate in athletic activities. The purpose of this study was to describe the clinical features of CAMRSA skin infection that occurred in university student athletes, evaluate the potential mechanisms for the transmission of MRSA infection of the skin in participants of athletic activities, and review the measures for preventing the spread of cutaneous CAMRSA infection in athletes.

METHODS

A retrospective chart review of the student athletes from the University of Houston whose skin lesions were evaluated at the Health Center and grew MRSA was performed. The clinical characteristics and the postulated mechanisms of cutaneous MRSA infection in the athletes were compared with those previously published in reports of CAMRSA skin infection outbreaks in other sports participants.

RESULTS

Cutaneous CAMRSA infection occurred in seven student athletes (four women and three men) who were either weight lifters (three students) or members of a varsity sports team: volleyball (two women), basketball (one woman), and football (one man). The MRSA skin infection presented as solitary or multiple, tender, erythematous, fluctuant abscesses with surrounding cellulitis. The lesions were most frequently located in the axillary region (three weight lifters), on the buttocks (two women), or on the thighs (two women). The drainage from all of the skin lesions grew MRSA, which was susceptible to clindamycin, gentamicin, rifampin, trimethoprim/sulfamethoxazole, and vancomycin; five of the isolates were also susceptible to ciprofloxacin and levofloxacin. All of the bacterial strains were resistant to erythromycin, oxacillin, and penicillin. The cutaneous MRSA infections persisted or worsened in the six athletes who were empirically treated for methicillin-sensitive S. aureus at their initial visit. Complete resolution of the skin infection occurred after the abscesses had been drained and the athlete had been treated with systemic antimicrobial therapy for which the bacterial strain was susceptible.

CONCLUSIONS

Cutaneous CAMRSA infection typically presents as an abscess, with or without surrounding cellulitis, in otherwise healthy participants of athletic activities who have or do not have MRSA-associated risk factors. Athletes who have MRSA skin infections include weight lifters and team members from competitive sports such as basketball, fencing, football, rugby, volleyball, and wrestling. Bacterial culture of suspected infectious skin lesions should be performed to establish the diagnosis of cutaneous MRSA infection and to determine the antibiotic susceptibility of the bacterial isolate. Treatment of cutaneous MRSA infection involves drainage of the abscess (either spontaneously or after incision) and appropriate systemic antimicrobial therapy. Direct skin-to-skin physical contact with infectious lesions or drainage, skin damage that facilitates the entry of bacteria, and sharing of infected equipment, clothing, or personal items may result in the acquisition and transmission of MRSA infection in participants of athletic activities. Earlier detection and topical treatment of the athlete's skin wounds by their coaches, avoidance of contact with other participants' cutaneous lesions and their drainage, and good personal hygiene are measures that can potentially prevent the spread of cutaneous MRSA infection in participants of athletic activities.

Staphylococcus aureus bacteremia, Australia

S. aureus bacteremia in Australia is increasingly caused by MRSA, which is likely to affect empiric prescribing of antimicrobial drugs in suspected cases.

Staphylococcus aureus bacteremia (SAB) is common and increasing worldwide. A retrospective review was undertaken to quantify the number of cases, their place of acquisition, and the proportions caused by methicillin-resistant S. aureus (MRSA) in 17 hospitals in Australia. Of 3,192 episodes, 1,571 (49%) were community onset. MRSA caused 40% of hospital-onset episodes and 12% of community-onset episodes. The median rate of SAB was 1.48/1,000 admissions (range 0.61–3.24; median rate for hospital-onset SAB was 0.7/1,000 and for community onset 0.8/1,000 admissions). Using these rates, we estimate that ≈6,900 episodes of SAB occur annually in Australia (35/100,000 population). SAB is common, and a substantial proportion of cases may be preventable. The epidemiology is evolving, with >10% of community-onset SAB now caused by MRSA. This is an emerging infectious disease concern and is likely to impact on empiric antimicrobial drug prescribing in suspected cases of SAB.

Cefoxitin resistance as a surrogate marker for the detection of methicillin-resistant Staphylococcus aureus

OBJECTIVES

To evaluate the usefulness of cefoxitin when used as a surrogate marker for the detection of methicillin resistance.

PATIENTS AND METHODS

Eight hundred and seventy-one strains of Staphylococcus aureus, collected from eight tertiary referral centres serving diverse socio-economic populations, were included in the study using NCCLS disc diffusion and the agar dilution methods.

RESULTS

Using cefoxitin and NCCLS criteria for disc diffusion, the sensitivity and specificity for recognizing methicillin resistance were both 100%. Similar results were obtained when the strains were tested by the agar dilution method. The cefoxitin MICs for methicillin-susceptible strains were < or = 4 mg/L.

CONCLUSIONS

Testing with cefoxitin as a surrogate marker for the detection of methicillin resistance was very accurate with both disc diffusion and agar dilution methods. Such testing clearly distinguished methicillin-resistant strains of S. aureus from methicillin-susceptible strains.

Community-acquired methicillin-resistant Staphylococcus aureus: skin infection presenting as an axillary abscess with cellulitis in a college athlete

A healthy 19-year-old black man without any methicillin-resistant Staphylococcus aureus risk factors developed axillary boils after he began lifting weights at the university gym in Houston, TX. He presented with a large tender erythematous fluctuant abscess of his right axillae and a superiorly located smaller painful red indurated nodule; the surrounding cellulitis extended into the adjacent tissue (Figure). The abscess was incised, drained, and cultured. Empiric treatment with cephalexin 500 mg q.i.d. was given for 7 days. The culture grew methicillin-resistant S. aureus. Susceptibility testing of the S. aureus isolate was performed by Laboratory Corp. of America (Houston, TX); the Vitek system (Biomerieux, Hazelwood, MO) was used, and the specimen was incubated for 8 hours. Confirmation of methicillin resistance was performed using a methicillin-resistant S. aureus plate and the specimen was incubated for 24 hours. In addition to resistance to methicillin, the bacterial isolate was also resistant to ciprofloxacin, erythromycin, and penicillin. The S. aureus strain had intermediate susceptibility to levofloxacin and was susceptible to clindamycin, gentamicin, rifampin, tetracycline, trimethoprim/sulfamethoxazole, and vancomycin. The infection persisted and the antibiotic was changed to double strength trimethoprim/sulfamethoxazole, taken twice daily for 15 days. In addition, topical care included lesional and intranasal application of mupirocin 2% ointment and daily cleaning of the area with 10% povidone-iodine liquid soap. The skin infection completely resolved without recurrence within 2 weeks.

Genetic diversity among community methicillin-resistant Staphylococcus aureus strains causing outpatient infections in Australia

Increasing reports of the appearance of novel nonmultiresistant methicillin-resistant Staphylococcus aureus MRSA (MRSA) strains in the community and of the spread of hospital MRSA strains into the community are cause for public health concern. We conducted two national surveys of unique isolates of S. aureus from clinical specimens collected from nonhospitalized patients commencing in 2000 and 2002, respectively. A total of 11.7% of 2,498 isolates from 2000 and 15.4% of 2,486 isolates from 2002 were MRSA. Approximately 54% of the MRSA isolates were nonmultiresistant (resistant to less than three of nine antibiotics) in both surveys. The majority of multiresistant MRSA isolates in both surveys belonged to two strains (strains AUS-2 and AUS-3), as determined by pulsed-field gel electrophoresis (PFGE) and resistogram typing. The 3 AUS-2 isolates and 10 of the 11 AUS-3 isolates selected for multilocus sequence typing (MLST) and staphylococcal chromosomal cassette mec (SCCmec) analysis were ST239-MRSA-III (where ST is the sequence type) and thus belonged to the same clone as the eastern Australian MRSA strain of the 1980s, which spread internationally. Four predominant clones of novel nonmultiresistant MRSA were identified by PFGE, MLST, and SCCmec analysis: ST22-MRSA-IV (strain EMRSA-15), ST1-MRSA-IV (strain WA-1), ST30-MRSA-IV (strain SWP), and ST93-MRSA-IV (strain Queensland). The last three clones are associated with community acquisition. A total of 14 STs were identified in the surveys, including six unique clones of novel nonmultiresistant MRSA, namely, STs 73, 93, 129, 75, and 80slv and a new ST. SCCmec types IV and V were present in diverse genetic backgrounds. These findings provide support for the acquisition of SCCmec by multiple lineages of S. aureus. They also confirm that both hospital and community strains of MRSA are now common in nonhospitalized patients throughout Australia.

Community-onset methicillin-resistant Staphylococcus aureus bacteremia in Northern Australia

BACKGROUND

Community-onset infections caused by methicillin-resistant Staphylococcus aureus (COMRSA) are being increasingly reported worldwide.

METHODS

A retrospective study was performed of 14 patients with 15 episodes of COMRSA bacteremia (COMRSAB) admitted to the Royal Darwin Hospital, Northern Territory, Australia from 1998 to 2001. Isolates from COMRSAB episodes underwent extended susceptibility testing and molecular typing by pulsed field gel electrophoresis and allotyping of the staphylococcal cassette chromosome mec (SCCmec) region by polymerase chain reaction.

RESULTS

The proportion of community-onset S. aureus bacteremia episodes that were due to COMRSA increased from 9% in 1998 to 20% in 2001. The clinical features of COMRSAB were similar to those seen with methicillin-susceptible strains, including sepsis, endocarditis and metastatic infection. Ineffective empiric antimicrobial therapy was administered in the majority (80%) of episodes. All COMRSAB isolates tested contained allotype IV SCCmec, which is commonly found in community isolates of MRSA and rarely found in isolates from healthcare-associated MRSA infection.

CONCLUSION

The increasing incidence of COMRSAB in our region has resulted in the addition of vancomycin to standard empiric therapy in certain patients with suspected S. aureus bacteremia acquired in the community.

Are the new quinolones appropriate treatment for community-acquired methicillin-resistant Staphylococcus aureus?

The use of quinolones in the treatment of non-serious community-acquired methicillin-resistant Staphylococcus aureus is discussed. The new C8-modified quinolones may be suitable for such treatment but controlled trials should be carried out to ensure that the pharmacokinetics are such that there is little risk of resistance developing.

Preliminary study of community-acquired Staphylococcus aureus infection in Manaus Hospital, Amazonia Region, Brazil

Methicillin resistant Staphylococcus aureus is considered a public health problem with a strong potential for dissemination and high rates of morbidity and mortality. In this study we describe bacteriological and epidemiological characteristics of Staphylococcus aureus in Manaus (Amazon region). During the one-year study period (2000-2001), sixteen cases of acute pyogenic multiple abscess were evaluated. Community-acquired S. aureus was identified as causative agent in 10 (62.5%) patients. The strains tested with antimicrobials by discs diffusion method, exhibited a high rate of sensitivity to cephalexin (100%), erythromycin (90%). Oxacillin-susceptible Staphylococcus aureus was 90%. No isolate was resistant to Vancomycin. To our knowledge, no series of community-acquired Staphylococcus aureus in Manaus hospital has been published. Our partial results showed a high rate of antimicrobial sensitivity among community-acquired Staphylococcus aureus in the hospital of Tropical Medicine Institute of Manaus, Amazon Region.

Community-acquired methicillin-resistant staphylococcus aureus skin infection: an emerging clinical problem

Community-acquired methicillin-resistant Staphylococcus aureus skin infections at an outpatient university health center were evaluated. In all, 41 cultures were performed in 36 of 853 patients. Of the 19 patients with S aureus infection, methicillin resistance occurred in 10 (53%) and generally manifested as abscesses or cellulitis. Therefore, methicillin resistance should be considered, even in the community setting, and appropriate cultures performed.

Antimicrobial resistance in Staphylococcus aureus in Australian teaching hospitals, 1989-1999

An annual survey of antimicrobial resistance in clinical isolates of Staphylococcus aureus was conducted in 21 Australian teaching hospital microbiology laboratories in eight major cities from 1989 to 1999. A total of 19,000 isolates were tested for susceptibility to 18 antimicrobials, with 3795 being methicillin-resistant (MRSA). Resistance to ciprofloxacin in MRSA increased from 4.9% to 75.9%. The proportion of MRSA resistant to erythromycin decreased significantly (99.0%-88.9%), as did that to trimethoprim (98.4%-82.4%) and to tetracycline (96.5%-80.1%). The proportion of MRSA isolated increased in Sydney, Melbourne, Canberra, Adelaide, Perth, and Darwin, but not in Brisbane. The proportion in Hobart peaked in 1994. MRSA in Perth were predominantly non-multiresistant (nmMRSA) throughout the survey (i.e., resistant to less than three of eight indicator antibiotics) due mainly to local strains that originated in the community. The proportion of nmMRSA increased to modest levels in the other cities. In eastern cities, this was due to the appearance of strains closely related to nmMRSA seen in other countries of the southwestern Pacific.

Emergence of community-acquired methicillin-resistant Staphylococcus aureus (MRSA) infection in Queensland, Australia

OBJECTIVES

To investigate the incidence and epidemiology of non-multiresistant methicillin-resistant Staphylococcus aureus (nmMRSA) infection in south-east Queensland, Australia.

STUDY DESIGN

A retrospective survey was done of hospital records of all patients who had non-multiresistant MRSA isolated at Ipswich Hospital (a 250-bed general hospital, 40 km south-west of Brisbane, Queensland, Australia) between March 2000 and June 2001. Laboratory typing of these isolates was done with antibiogram, pulsed-field gel electrophoresis, bacteriophage typing and coagulase gene typing.

RESULTS

There were 44 infections caused by nmMRSA. Seventeen infections (39%) occurred in patients from the south-west Pacific Islands (predominantly Samoa, Tonga and New Zealand). Laboratory typing showed that the isolates in Pacific Islanders were Pacific Island strains, and 16/17 of these infections were community acquired. Twenty-three infections (52%) occurred in Caucasians. Eleven of the isolates from Caucasians (48%) were a new predominantly community-acquired strain that we have termed the 'R' pulsotype, nine (39%) were Pacific Island strains, and three (13%) were health care institution-associated strains. Four infections occurred in patients who were not Caucasians or Pacific Islanders. Overall, 34 of all 44 infections (77%) were community acquired.

CONCLUSIONS

Non-multiresistant MRSA infection, relatively frequently observed in Pacific Islanders in south-east Queensland, is now a risk for Caucasians as well, and is usually community acquired. Clinicians should consider taking microbiological specimens for culture and antimicrobial susceptibility testing in patients with suspected staphylococcal infections who are not responding to empirical therapy with beta-lactam antibiotics.

Community-acquired methicillin-resistant Staphylococcus aureus carrying Panton-Valentine leukocidin genes: worldwide emergence

Infections caused by community-acquired (CA)-methicillin--resistant Staphylococcus aureus (MRSA) have been reported worldwide. We assessed whether any common genetic markers existed among 117 CA-MRSA isolates from the United States, France, Switzerland, Australia, New Zealand, and Western Samoa by performing polymerase chain reaction for 24 virulence factors and the methicillin-resistance determinant. The genetic background of the strain was analyzed by pulsed-field gel electrophoresis (PFGE) and multi-locus sequence typing (MLST). The CA-MRSA strains shared a type IV SCCmec cassette and the Panton-Valentine leukocidin locus, whereas the distribution of the other toxin genes was quite specific to the strains from each continent. PFGE and MLST analysis indicated distinct genetic backgrounds associated with each geographic origin, although predominantly restricted to the agr3 background. Within each continent, the genetic background of CA-MRSA strains did not correspond to that of the hospital-acquired MRSA.