Fusidic acid and clindamycin resistance in community-associated, methicillin-resistant Staphylococcus aureus infections in children of Central Greece

Predominance of community-associated, methicillin-susceptible Staphylococcus aureus infections among hospitalized children and adolescents

Introduction. Staphylococcus aureus infections cause significant morbidity and mortality in children and adolescents.Gap Statement. There is limited data on the characteristics of S. aureus infections requiring hospitalization in childhood.Aim.To investigate the molecular epidemiology and antibiotic resistance of S. aureus clinical isolates from children and adolescents.Methodology.All S. aureus isolates recovered from patients aged <18 years, admitted to a referral hospital, with culture-proven invasive or non-invasive infections during the 4 year period 2015 to 2018 were analysed for antimicrobial resistance, virulence genes, PFGE and multilocus sequence typing (MLST). Cases were assigned to community-associated, community-onset healthcare-associated or hospital-associated infections based on epidemiological case definitions.Results.Among 139 S. aureus infections, 88.5 % (123/139) were caused by methicillin-susceptible isolates (MSSA) and 73.4 % (102/139) were classified as community-associated infections. tst and lukS/lukF-PV genes were more common among MRSA as compared to MSSA isolates (tst, p 0.04; lukS/lukF-PV, p 0.007). Invasive disease was noted in 22/139 patients (15.8 %). Staphylococcal scalded skin syndrome caused by fusidic-resistant MSSA increased over time (22.8 % in 2017-2018 vs 8.3 % in 2015-2016, OR 3.24; 95 % CI 1.10-8.36; P 0.03). By PFGE genotyping, 22 pulsotypes were identified. A total of five sequence types (STs) were identified among 58 isolates analysed by MLST. More than one third of MSSA isolates (40/123, 32.5 %) and 13/23 (56.5 %) of SSSS isolates belonged to pulsotype 1, classified as sequence type 121 (ST121). MRSA isolates were equally distributed to pulsotypes A (ST30), B (ST239), C (ST80), H (ST225). ST121 isolates carried fnbA (40/40), eta/etb genes (29/40), exhibited high resistance to fusidic acid and were increasingly resistant to mupirocin.Conclusion.In our population, community-associated MSSA was the predominant cause of S. aureus infections characterized by polyclonality, increasing resistance to fusidic acid and mupirocin. PFGE type 1 ST121 clone, harboured exfoliative toxin genes and was associated with rising trends of SSSS.

The Bacteriology of Skin Lesions in Patients with Hidradenitis Suppurativa Is Associated with Previous Antibiotic Treatment in the Community Setting: A Referral Center Experience

BACKGROUND

Hidradenitis suppurativa (HS) is a chronic skin disease characterized by inflammatory nodules and abscesses. The pathogenic role of bacteria is not fully understood. As the diagnosis is usually delayed, patients are often treated with several lines of antibiotics in a nonstandardized fashion. The aim of the study was to investigate and compare the bacteriology of active HS lesions in patients treated or not treated with antibiotics in the community setting before referral to a dedicated HS clinic.

METHODS

Purulent skin lesions of patients with HS referred to the HS Clinic of Rabin Medical Center in 2009-2020 were cultured. Data were collected from the patients' medical files and microbiology reports. The correlation between the location of the skin lesion and the bacteriologic profile was analyzed, and the effects of previous antibiotic treatment on the bacteriologic profile of the lesions and susceptibility patterns of the cultured bacteria were evaluated.

RESULTS

Pus (or tissue) from inflammatory lesions of 97 patients with HS was cultured. Mean (SD) patient age was 39.5 (13.0) years, and mean delay in diagnosis was 7.3 (8.3) years. Most patients (57.7%) had dominant involvement of one location, with the most active lesions concentrated in the genitalia, gluteal/perineal area, and axilla. Enterobacterales species were the most frequent isolates detected in all locations except the face and scalp. Seventy-eight patients (80.4%) had been treated in the community setting prior to referral with a median (range) of 2 (1-8) lines of antibiotics. The most commonly prescribed antibiotics were amoxicillin/clavulanate (22.0%), doxycycline/minocycline (16.8%), clindamycin (16.2%; monotherapy 8.1%, clindamycin with rifampicin 8.1%), and cephalexin (13.9%). Compared to the previously untreated patients, cultures of lesions from the previously treated patients yielded a higher percentage of gram-negative Enterobacterales (the most common isolates in this group) (31.3% vs. 10.3%) and a significantly higher median number of isolates per culture (2 vs. 1, p < 0.0001). Gram-positive bacteria, usually considered contaminants (mainly coagulase-negative staphylococci) accounted for 31.0% of the isolates in the previously treated group. Susceptibility testing for the entire cohort revealed 100% bacterial sensitivity to ciprofloxacin. Staphylococcus spp. were 100% sensitive to rifampicin. Both gram-positive and gram-negative bacteria had high sensitivity to trimethoprim and sulfamethoxazole.

CONCLUSION

Nonstandardized antibiotic treatment of HS in the community setting can skew the microbiology of skin lesions toward gram-negative bacteria. Therefore, treatment with trimethoprim and sulfamethoxazole or ciprofloxacin, either alone or combined with rifampicin, may be considered.

Fusidic Acid Resistance Determinants in Methicillin-Resistant Staphylococcus aureus Isolated in Kuwait Hospitals

OBJECTIVE

The aim of this study was to investigate the genetic determinants of fusidic acid (FA) resistance in MRSA isolated from patients in Kuwait hospitals.

METHODS

The minimum inhibitory concentration (MIC) of FA was tested with E-test strips. Genetic determinants of FA were determined by PCR and DNA microarray. Staphylococcal protein A gene (spa) typing and DNA microarray analysis were used to study their genetic backgrounds.

RESULTS

The FA MIC ranged from 2 mg/L to >256 mg/L. Of the 97 isolates, 79 (81.4%) harbored fusC, 14 isolates harbored fusA mutations (fusA), and 4 isolates harbored fusB. Isolates with fusA mutations expressed high FA MIC (MIC >256 mg/L), whereas those with fusC and fusB expressed low FA MIC (MIC 2-16 mg/L). The isolates belonged to 23 spa types and 12 clonal complexes (CCs). The major spa types were t688 (n = 25), t311 (n = 14), t860 (n = 8), and t127 (n = 6) which constituted 54.6% of the isolates. The 12 CCs were CC1, CC5, CC8, CC15, CC22, CC80, CC88, and CC97 with CC5 (45.6%) and CC97 (13.2%) as the dominant CCs.

CONCLUSIONS

The MRSA isolates belonged to diverse genetic backgrounds with the majority carrying the fusC resistance determinants. The high prevalence of FA resistance belonging to diverse genetic backgrounds warrants a review of FA usage in the country to preserve its therapeutic benefits.

Intolerable Burden of Impetigo in Endemic Settings: A Review of the Current State of Play and Future Directions for Alternative Treatments

Impetigo (school sores) is a common superficial bacterial skin infection affecting around 162 million children worldwide, with the highest burden in Australian Aboriginal children. While impetigo itself is treatable, if left untreated, it can lead to life-threatening conditions, such as chronic heart and kidney diseases. Topical antibiotics are often considered the treatment of choice for impetigo, but the clinical efficacy of these treatments is declining at an alarming rate due to the rapid emergence and spread of resistant bacteria. In remote settings in Australia, topical antibiotics are no longer used for impetigo due to the troubling rise of antimicrobial resistance, demanding the use of oral and injectable antibiotic therapies. However, widespread use of these agents not only contributes to existing resistance, but also associated with adverse consequences for individuals and communities. These underscore the urgent need to reinvigorate the antibiotic discovery and alternative impetigo therapies in these settings. This review discusses the current impetigo treatment challenges in endemic settings in Australia and explores potential alternative antimicrobial therapies. The goals are to promote intensified research programs to facilitate effective use of currently available treatments, as well as developing new alternatives for impetigo.

Methicillin-Resistant Staphylococcus aureus ST80 Clone: A Systematic Review

This review assessed the molecular characterization of the methicillin-resistant Staphylococcus aureus (MRSA)-ST80 clone with an emphasis on its proportion of total MRSA strains isolated, PVL production, spa-typing, antibiotic resistance, and virulence. A systematic review of the literature was conducted on MRSA-ST80 clone published between 1 January 2000 and 31 August 2019. Citations were chosen for a review of the full text if we found evidence that MRSA-ST80 clone was reported in the study. For each isolate, the country of isolation, the sampling period, the source of isolation (the type of infection, nasal swabs, or extra-human), the total number of MRSA strains isolated, number of MRSA-ST80 strains, antibiotic resistance patterns, PVL production, virulence genes, and spa type were recorded. The data from 103 articles were abstracted into an Excel database. Analysis of the data showed that the overall proportion of MRSA-ST80 has been decreasing in many countries in recent years. The majority of MRSA-ST80 were PVL positive with spa-type t044. Only six reports of MRSA-ST80 in extra-human niches were found. This review summarizes the rise of MRSA-ST80 and the evidence that suggests that it could be in decline in many countries.

Antimicrobial overuse and misuse in the community in Greece and link to antimicrobial resistance using methicillin-resistant S. aureus as an example

Both antimicrobial consumption and antimicrobial resistance are very high in Greece, ranking among the highest of Europe. The link between antimicrobial consumption and resistance is well-known. Here, we discuss the reasons of antimicrobial overuse in Greece in the community (such as self-medication, dispersion of antibiotics by pharmacies without prescription, over-prescription by physicians, patient expectations and liability pressure) and we explore the misuse of antibiotics for common community infections. Furthermore, we discuss how such overuse/misuse can drive antimicrobial resistance, using methicillin-resistance in Staphylococcus aureus as an example. S. aureus is one of the pathogens with high rates of resistance in Greece. Comparing the rate of antimicrobial susceptibility to non-beta lactams between methicillin-resistant and methicillin-sensitive S. aureus we highlight the antibiotics that have the potential to drive methicillin-resistance through co-selection. Based on the above we identify targets for intervention in order to reduce antimicrobial overuse/misuse in the community in Greece.

Changes in the rates and population structure of methicillin-resistant Staphylococcus aureus (MRSA) from bloodstream infections: A single-centre experience (2000-2015)

OBJECTIVES

The aim of this study was to assess the rate of methicillin-resistant Staphylococcus aureus (MRSA) bloodstream infections (BSIs) and the population structure of MRSA isolates recovered between 2000-2015 in a tertiary-care hospital in Athens, Greece.

METHODS

Non-duplicate MRSA blood isolates recovered during the study period were examined. Antimicrobial susceptibility testing was performed by Kirby-Bauer and gradient strip methods. Carriage of PVL and mecA genes was examined by PCR. Genetic relatedness of the isolates was studied by SCCmec, spa and multilocus sequence typing.

RESULTS

A total of 398 MRSA BSI cases were identified. A decreasing trend in incidence from 1.69/10 000 patient-days in 2000 to 1.39/10 000 patient-days in 2015 (P=0.038) and in prevalence from 64.7% to 36.4% (P=0.008), respectively, was observed, whereas the incidence of methicillin-susceptible S. aureus BSI increased. MRSA isolates exhibiting resistance to common antistaphylococcal agents (excluding glycopeptides and the newer antistaphylococcals) decreased from 84.8% in 2000 to 0% in 2011 and were progressively 'replaced' by more susceptible phenotypes. A strong association between antimicrobial resistance phenotype and molecular type was observed. The pandemic HA-MRSA clone ST239-III progressively declined in parallel with increasing isolation frequency of two clonal complexes (CCs): HA-MRSA CC5, with the majority of isolates belonging to ST5-II; and CA-MRSA CC80, represented mainly by ST80-IV-t044, PVL+.

CONCLUSION

The decline in MRSA BSI rates observed in our institution was associated with changes in population structure of the organism. This decline may be related to biological properties of the prevailing MRSA clones.

Decolonization of Staphylococcus aureus in patients with atopic dermatitis: a reason for increasing resistance to antibiotics?

INTRODUCTION

Exacerbation of atopic dermatitis can be associated with bacterial infection. The skin of patients is colonized with Staphylococcus aureus in 90% of cases. An attempt has been made to demonstrate that eradication significantly reduces the severity of the disease. Studies indicate the efficacy of topical antibiotics, topical corticosteroids and calcineurin inhibitors. Due to increasing resistance to drugs and the defective antimicrobial peptide profile, decolonization is virtually impossible.

AIM

To determine the prevalence of S. aureus colonization among patients with atopic dermatitis and to assess antimicrobial susceptibility of isolated strains to antibiotics, especially fusidic acid and mupirocin.

MATERIAL AND METHODS

One hundred patients with atopic dermatitis and 50 healthy subjects were microbiologically assessed for the carriage of S. aureus. Antimicrobial susceptibility tests were performed using the broth-microdilution method for antibiotics: ampicillin, ciprofloxacin, daptomycin, erythromycin, fusidic acid, linezolid, lincomycin, mupirocin, tetracycline and vancomycin.

RESULTS

Staphylococcus aureus strains were isolated from the majority of our patients, either from the skin (71%) or the anterior nares (67%). In the present study, 10% of isolations represented methicillin-resistant S. aureus (MRSA). Antibiotics exhibited diverse activities against clinical isolates of S. aureus. Among those tested, the highest rates of resistance were shown for ampicillin - 58.5%, lincomycin - 37.5% and erythromycin - 31.0%. Enhanced resistance levels were expressed to mupirocin (17.5%) and fusidic acid (15.5%).

CONCLUSIONS

According to the increasing rate of resistance and quick recolonization after discontinuation of the treatment, chronic use of topical antibiotics is not recommended and should be limited to exacerbation of atopic dermatitis with clinical signs of bacterial infection.

Methicillin Resistant Staphylococcus aureus Transmission in a Ghanaian Burn Unit: The Importance of Active Surveillance in Resource-Limited Settings

Objectives:Staphylococcus aureus infections in burn patients can lead to serious complications and death. The frequency of S. aureus infection is high in low- and middle-income countries presumably due to limited resources, misuse of antibiotics and poor infection control. The objective of the present study was to apply population genomics to precisely define, for the first time, the transmission of antibiotic resistant S. aureus in a resource-limited setting in sub-Saharan Africa.

Methods:Staphylococcus aureus surveillance was performed amongst burn patients and healthcare workers during a 7-months survey within the burn unit of the Korle Bu Teaching Hospital in Ghana.

Results: Sixty-six S. aureus isolates (59 colonizing and 7 clinical) were obtained from 31 patients and 10 healthcare workers. Twenty-one of these isolates were ST250-IV methicillin-resistant S. aureus (MRSA). Notably, 25 (81%) of the 31 patients carried or were infected with S. aureus within 24 h of admission. Genome comparisons revealed six distinct S. aureus clones circulating in the burn unit, and demonstrated multiple transmission events between patients and healthcare workers. Further, the collected S. aureus isolates exhibited a wide range of genotypic resistances to antibiotics, including trimethoprim (21%), aminoglycosides (33%), oxacillin (33%), chloramphenicol (50%), tetracycline (59%) and fluoroquinolones (100%).

Conclusion: Population genomics uncovered multiple transmission events of S. aureus, especially MRSA, within the investigated burn unit. Our findings highlight lapses in infection control and prevention, and underscore the great importance of active surveillance to protect burn victims against multi-drug resistant pathogens in resource-limited settings.

Daptomycin Use in Children: Experience With Various Types of Infection and Age Groups

BACKGROUND

In Greece, there are high rates of methicillin (40%-60%) and clindamycin (15%-25%) resistance among community-acquired Staphylococcus aureus isolates. Therefore, we sought to identify other antimicrobial treatment options such as daptomycin.

METHODS

We studied retrospectively all pediatric infections treated with daptomycin at the University General Hospital of Larissa, Greece, from January 1, 2007, to June 16, 2016.

RESULTS

Of a total of 128 patients (median age: 2.8 years; range: 8 days to 14.5 years; 76.6% <7 years) treated with daptomycin, 45 (35.2%) had invasive infection, most frequently musculoskeletal, and 83 (64.8%) had noninvasive infection, that is, complicated skin and soft tissue infection. S. aureus was the most commonly recovered pathogen (n = 61) (63.9% methicillin-resistant isolates, 21.3% clindamycin-resistant). The average daily dose of daptomycin was 10 mg/kg qd, and the median duration of therapy was 10 days. Daptomycin was administered alone (n = 61) or in combination therapy (n = 67), most frequently with rifampin (n = 40) and/or a β-lactam antibiotic (n = 33). Open or closed drainage was performed in 86 (67.2%) of the total number of patients. Of 128 treated patients, 123 (96.1%) achieved clinical success, 114 (89.1%) had complete remission, and 9 (7%) had improvement of their disease. There were no failures with daptomycin therapy. The adverse events were of no clinical significance.

CONCLUSIONS

Daptomycin administered alone or in combination with other antimicrobial agents to children was efficacious and well tolerated in the treatment of complicated infections of suspected or proven staphylococcal etiology.

Clonal spread of methicillin-resistant Staphylococcus aureus-t6065-CC5-SCCmecV-agrII in a Libyan hospital

OBJECTIVES

The aim of this study was to characterize 32 MRSA isolates recovered from wound specimens of patients in a Hospital in Tripoli, Libya, during 2013.

METHODS

MRSA isolates were characterized by determining their antibiotic susceptibilities, genes encoding antibiotic resistance and virulence factors, the SCCmec class, agr type, spa typing, PFGE and MLST.

RESULTS

PFGE and MLST revealed that all isolates were clonal and belonged to the Clonal Complex 5 (CC5). They harboured the SCCmecV and the agrII and the spa type was t6065. The majority of isolates were resistant to cefoxitin (32, 100%), penicillin (32, 100%), ampicillin (32, 100%), enrofloxacin (32, 100%), ciprofloxacin (32, 100%), fusidic acid (32, 100%), gentamicin (32, 100%), kanamycin (32, 100%), trimethoprim (32, 100%), and erythromycin (30, 93.7%). The main genes encoding antibiotic resistance were: blaZ (31, 96.8%), ermC (30, 93.7%), aph(3')-III a (3, 9.4%), aac6-aph2 (32, 100%), InuA (3, 9.4%), tetM (3, 9.4%), tetL (3, 9.4%), dfrG (28, 87.5%), fusC (32, 100%). All isolates were PVL negative; however, exfoliative-encoding genes (eta: 25) and enterotxin genes (seb: 32, seo: 32, sei: 32, ser: 32, seu: 32, seg: 32, sej: 32, sed: 31, sen: 29, seh: 26, sec: 26, sea: 6, sek: 5), haemolysin (hla (32), hld (32), hlg (32)) and immune evasion cluster proteins (scn: 32, sak: 32) were relevant.

CONCLUSION

To the best of our knowledge this is the first report of a specific clonal spread of a multi-drug resistant MRSA-CC5- SCCmecV in a Libyan Hospital.

A study of community-associated methicillin-resistant Staphylococcus aureus in patients with pyoderma

BACKGROUND

Health care-associated methicillin-resistant Staphylococcus aureus(HA-MRSA) are resistant to multiple antibiotics, therefore infections caused by them are difficult to treat resulting in high morbidity and mortality. While most of the research activities and public health initiatives are focused on HA-MRSA, the newly emerging pathogen, community-associated methicillin-resistant Staphylococcus aureus(CA-MRSA) is gaining in significance in respect to patient morbidity. There is a significant paucity of data regarding CA-MRSA in the developing parts of the world.

AIM

To study the proportions of HA-MRSA and CA-MRSA infections among patients with culture-proven S. aureus infection and to find out how many of these patients showed presence of MRSA in nasal cultures of healthy contacts.

MATERIALS AND METHODS

Clinical details of 227 patients were recorded in the study, such as the duration and recurrence of the infection, history of antibiotic intake, and the presence of other medical illnesses. A pus swab was taken from each lesion and sent for culture and sensitivity. If the culture grew S. aureus, they were screened for methicillin resistance. A swab from the anterior nares of the healthy contact of each patient, whenever available, was collected and it was screened for MRSA.

RESULTS

Furunculosis was most common among the primary pyodermas (53/134; 39. 5%). Out of 239 pus culture samples obtained from 227 patients, 192 (84.58%) grew S. aureus; of these 150 (78.12%) were methicillin-sensitive S. aureus (MSSA), whereas 42 (21.98%) were MRSA. Out of the 42 MRSA isolated, 33 turned out to be CA-MRSA (78%) and 9 (22%) were HA-MRSA. Nasal swabs of healthy contacts of 34 MRSA patients were cultured. Out of them, two grew MRSA in the culture.

CONCLUSION

The isolation rate of S. aureus was high in our study. Furthermore, our study, although hospital based, clearly indicated the substantial magnitude of the CA-MRSA problem in the local population.

Kingella kingae sequence type-complex 14 arthritis in a 16-month-old child in Greece

We describe the first case of Kingella kingae arthritis in a 16-month-old girl in Greece, which has been diagnosed by novel molecular techniques. A joint aspiration of her knee was performed before the initiation of antibiotics, as well as on the 5th and 14th day of empiric antimicrobial therapy. The synovial fluid white blood cell count decreased from 65,000 to 1500 cells/mm, but the percentage of neutrophils remained 90% in all 3 specimens. Molecular analysis of the synovial fluid specimens by real-time polymerase chain reaction and multilocus sequence typing enabled us to reveal the presence of K. kingae belonging to the international sequence type-complex 14, which persisted up to the fifth day of antibiotic therapy.

A new strategy to fight antimicrobial resistance: the revival of old antibiotics

The increasing prevalence of hospital and community-acquired infections caused by multidrug-resistant (MDR) bacterial pathogens is limiting the options for effective antibiotic therapy. Moreover, this alarming spread of antimicrobial resistance has not been paralleled by the development of novel antimicrobials. Resistance to the scarce new antibiotics is also emerging. In this context, the rational use of older antibiotics could represent an alternative to the treatment of MDR bacterial pathogens. It would help to optimize the armamentarium of antibiotics in the way to preserve new antibiotics and avoid the prescription of molecules known to favor the spread of resistance (i.e., quinolones). Furthermore, in a global economical perspective, this could represent a useful public health orientation knowing that several of these cheapest “forgotten” antibiotics are not available in many countries. We will review here the successful treatment of MDR bacterial infections with the use of old antibiotics and discuss their place in current practice.

Origin and evolution of European community-acquired methicillin-resistant Staphylococcus aureus

Community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) was recognized in Europe and worldwide in the late 1990s. Within a decade, several genetically and geographically distinct CA-MRSA lineages carrying the small SCCmec type IV and V genetic elements and the Panton-Valentine leukocidin (PVL) emerged around the world. In Europe, the predominant CA-MRSA strain belongs to clonal complex 80 (CC80) and is resistant to kanamycin/amikacin and fusidic acid. CC80 was first reported in 1993 but was relatively rare until the late 1990s. It has since been identified throughout North Africa, the Middle East, and Europe, with recent sporadic reports in sub-Saharan Africa. While strongly associated with skin and soft tissue infections, it is rarely found among asymptomatic carriers. Methicillin-sensitive S. aureus (MSSA) CC80 strains are extremely rare except in sub-Saharan Africa. In the current study, we applied whole-genome sequencing to a global collection of both MSSA and MRSA CC80 isolates. Phylogenetic analyses strongly suggest that the European epidemic CA-MRSA lineage is derived from a PVL-positive MSSA ancestor from sub-Saharan Africa. Moreover, the tree topology suggests a single acquisition of both the SCCmec element and a plasmid encoding the fusidic acid resistance determinant. Four canonical SNPs distinguish the derived CA-MRSA lineage and include a nonsynonymous mutation in accessory gene regulator C (agrC). These changes were associated with a star-like expansion into Europe, the Middle East, and North Africa in the early 1990s, including multiple cases of cross-continent imports likely driven by human migrations.

With increasing levels of CA-MRSA reported from most parts of the Western world, there is a great interest in understanding the origin and factors associated with the emergence of these epidemic lineages. To trace the origin, evolution, and dissemination pattern of the European CA-MRSA clone (CC80), we sequenced a global collection of strains of the S. aureus CC80 lineage. Our study determined that a single descendant of a PVL-positive methicillin-sensitive ancestor circulating in sub-Saharan Africa rose to become the dominant CA-MRSA clone in Europe, the Middle East, and North Africa. In the transition from a methicillin-susceptible lineage to a successful CA-MRSA clone, it simultaneously became resistant to fusidic acid, a widely used antibiotic for skin and soft tissue infections, thus demonstrating the importance of antibiotic selection in the success of this clone. This finding furthermore highlights the significance of horizontal gene acquisitions and underscores the combined importance of these factors for the success of CA-MRSA.

Detection and genetic characterization of PVL-positive ST8-MRSA-IVa and exfoliative toxin D-positive European CA-MRSA-Like ST1931 (CC80) MRSA-IVa strains in Bangladesh

Severe skin lesions caused by Staphylococcus aureus infection are associated with production from bacterial cells of Panton-Valentine leukocidin (PVL), a typical virulence factor of community-acquired methicillin-resistant S. aureus (CA-MRSA), as well as other toxins represented by exfoliative toxins. Through a retrospective study of 26 S. aureus strains isolated from skin lesions of diabetic patients admitted to a hospital in Bangladesh, 2 PVL-gene-positive MRSA-IVa strains and 8 PVL-negative, exfoliative toxin D (ETD) gene (etd)-positive MRSA-IVa strains were isolated. A PVL-positive MRSA-IVa strain had a type I arginine catabolic mobile element (ACME), belonged to ST8/agr-type I/spa-type t121 (a variant of t008), and harbored blaZ, tet(K), msrA, and aph(3')-IIIa, which are mostly typical characteristics found in USA300, a predominant CA-MRSA clone in the United States. Another PVL-positive MRSA strain, belonging to ST1929 (CC88)/agr-type III/spa-type t3341, was negative for ACME, but possessed blaZ and tet(K). The etd-positive MRSA-IVa strains possessed the epidermal cell differentiation inhibitor B (EDIN-B)-encoding gene (edinB) and belonged to ST1931 (CC80)/agr-type III/spa-type t11023 (a variant of t044), which was genetic trait similar to that of the European CA-MRSA ST80 clone. However, unlike the European ST80 strains, the etd-positive MRSA strains detected in the present study harbored seb, sek, and seq, while they were negative for tet(K), aph(3')-IIIa, and fusB, showing susceptibility to fusidic acid. These findings suggested that etd-positive ST1931 MRSA strains belong to the same lineage as the European ST80 MRSA clone, evolving from a common ancestral clone via acquisition of a different pathogenicity island. This is the first report of a USA300-like MRSA-IV strain, PVL-positive ST1929 (CC88) MRSA-IV, and European ST80 CA-MRSA-like etd-positive ST1931 (CC80) MRSA-IV strains isolated in Bangladesh.

The changing microbiologic epidemiology of community-acquired pneumonia

Community-acquired pneumonia (CAP) is a common infectious disease in the United States and the incidence continues to grow as the aging population increases. Overall, in-hospital patient mortality rates have been reported to be as high as 18%. Management of patients with CAP has been challenged by the evolution of resistant pathogens (particularly Streptococcus pneumoniae and Staphylococcus aureus) that have reduced susceptibility to recommended standard antimicrobial agents. Streptococcus pneumoniae continues to be the most frequently identified pathogen in CAP and recently, S. aureus has been found to be the second most often identified pathogen. Data from the SENTRY Antimicrobial Surveillance Program has shown declining susceptibility of pneumococci to penicillin, amoxicillin/clavulanate, and ceftriaxone from 1998 through 2011. In the Assessing Worldwide Resistance Evaluation (AWARE) surveillance program, > 50% of all S. aureus isolates from patient bloodstream infections, skin and skin structure infections, and pneumonia were methicillin-resistant. Stratifying risk factors to identify patients at risk for community-acquired multidrug-resistant pathogens should be considered when selecting therapy. Differences in microbiology and outcomes have been noted in patients presenting from the community with recent exposure to the health care system (eg, nursing home residents, patients with a recent hospital admission). These patients are at an increased risk of an infection caused by a multidrug-resistant pathogen. Understanding a patient's risk for drug-resistant pathogens will allow the physician to choose an appropriate empiric treatment regimen to optimize clinical outcomes.

Treatment of infections due to resistant Staphylococcus aureus

This chapter reviews data on the treatment of infections caused by drug-resistant Staphylococcus aureus, particularly methicillin-resistant S. aureus (MRSA). This review covers findings reported in the English language medical literature up to January of 2013. Despite the emergence of resistant and multidrug-resistant S. aureus, we have seven effective drugs in clinical use for which little resistance has been observed: vancomycin, quinupristin-dalfopristin, linezolid, tigecycline, telavancin, ceftaroline, and daptomycin. However, vancomycin is less effective for infections with MRSA isolates that have a higher MIC within the susceptible range. Linezolid is probably the drug of choice for the treatment of complicated MRSA skin and soft tissue infections (SSTIs); whether it is drug of choice in pneumonia remains debatable. Daptomycin has shown to be non-inferior to either vancomycin or β-lactams in the treatment of staphylococcal SSTIs, bacteremia, and right-sided endocarditis. Tigecycline was also non-inferior to comparator drugs in the treatment of SSTIs, but there is controversy about whether it is less effective than other therapeutic options in the treatment of more serious infections. Telavancin has been shown to be non-inferior to vancomycin in the treatment of SSTIs and pneumonia, but has greater nephrotoxicity. Ceftaroline is a broad-spectrum cephalosporin with activity against MRSA; it is non-inferior to vancomycin in the treatment of SSTIs. Clindamycin, trimethoprim-sulfamethoxazole, doxycycline, rifampin, moxifloxacin, and minocycline are oral anti-staphylococcal agents that may have utility in the treatment of SSTIs and osteomyelitis, but the clinical data for their efficacy is limited. There are also several drugs with broad-spectrum activity against Gm-positive organisms that have reached the phase II and III stages of clinical testing that will hopefully be approved for clinical use in the upcoming years: oritavancin, dalbavancin, omadacycline, tedizolid, delafloxacin, and JNJ-Q2. Thus, there are currently many effective drugs to treat resistant S. aureus infections and many promising agents in the pipeline. Nevertheless, S. aureus remains a formidable adversary, and despite our deep bullpen of potential therapies, there are still frequent treatment failures and unfortunate clinical outcomes. The following discussion summarizes the clinical challenges presented by MRSA, the clinical experience with our current anti-MRSA antibiotics, and the gaps in our knowledge on how to use these agents to most effectively combat MRSA infections.

Prevalence and molecular epidemiology of methicillin-resistant Staphylococcus aureus in a tertiary Greek hospital

BACKGROUND/AIM

Methicillin-resistant Staphylococcus aureus (MRSA) is a major cause of health- and community-associated infections; its prevalence in Greece is among the highest in Europe. We investigated the prevalence and molecular epidemiology of MRSA in a tertiary Greek hospital.

MATERIAL AND METHODS

Spa typing and random polymorphic DNA analysis were used to investigate the molecular epidemiology of 28 MRSA isolates during May 2010 to May 2011 in a tertiary hospital in Northern Greece.

RESULTS

Nine spa types were detected; t003 was the predominant (32.1%) one, detected in various wards and throughout the study period, while t037 was recovered only from intensive care unit patients, and only in April 2011, suggestive of an epidemic. Additional rare types were detected for the first time in Greece.

CONCLUSIONS

Spa typing and random polymorphic DNA analysis gave an insight into the epidemiology of MRSA in a Northern Greece hospital. Concerning the distribution in the hospital, the predominant spa type t003 was present in various wards, and was constantly detected throughout the study period, very suggestive of an epidemic, while other types were detected only in specific wards. Our data underline the need for surveillance, typing and constant reassessment of existing strategies to control MRSA.

Investigational antimicrobial agents of 2013

New antimicrobial agents are always needed to counteract the resistant pathogens that continue to be selected by current therapeutic regimens. This review provides a survey of known antimicrobial agents that were currently in clinical development in the fall of 2012 and spring of 2013. Data were collected from published literature primarily from 2010 to 2012, meeting abstracts (2011 to 2012), government websites, and company websites when appropriate. Compared to what was reported in previous surveys, a surprising number of new agents are currently in company pipelines, particularly in phase 3 clinical development. Familiar antibacterial classes of the quinolones, tetracyclines, oxazolidinones, glycopeptides, and cephalosporins are represented by entities with enhanced antimicrobial or pharmacological properties. More importantly, compounds of novel chemical structures targeting bacterial pathways not previously exploited are under development. Some of the most promising compounds include novel β-lactamase inhibitor combinations that target many multidrug-resistant Gram-negative bacteria, a critical medical need. Although new antimicrobial agents will continue to be needed to address increasing antibiotic resistance, there are novel agents in development to tackle at least some of the more worrisome pathogens in the current nosocomial setting.

Staphylococcus aureus and topical fusidic acid use: results of a clinical audit on antimicrobial resistance

BACKGROUND

Fusidic acid (FA) resistance in Staphylococcus aureus poses a problem for treating systemic methicillin-resistant S. aureus infection, in which FA may otherwise remain a viable option. It can also result in treatment failure of common dermatological conditions such as impetigo and infected atopic eczema. Several studies have linked trends in prescribing medication and topical use of FA to development of resistance. However, few case-control studies have evaluated risk factors for developing FA resistance in S. aureus.

METHODS

A clinical audit for antimicrobial resistance was performed in dermatology patients from the National Skin Centre who were admitted for inpatient care from 2006 to 2008 and had positive bacterial cultures for S. aureus. Each FA-resistant S. aureus (FRSA) case was compared with four randomly selected FA-susceptible (FSSA) cases. Medical records were reviewed retrospectively, and potential risk factors for development of resistance were analyzed.

RESULTS

Thirteen of 37 patients with FRSA (35.1%) had used FA topically compared with 11 of 148 patients with FSSA (7.4%). Findings from multivariate analysis indicate that previous use of topical FA was the only independent risk factor of FA resistance (adjusted OR 7.46, 95% CI [2.60-21.41], P < 0.001). Patients' coexisting illnesses, recent hospitalization, or systemic antibiotic use were not significant risks.

CONCLUSIONS

Previous recent topical FA use correlated positively with FA resistance in S. aureus. Prescribing physicians must be vigilant of the rise of FA resistance and its resultant problems and prescribe topical FA discerningly.

Antibiotic overuse and resistance in dermatology

Antibiotics have a significant role in dermatology, treating a wide range of diseases, including acne, rosacea, inflammatory skin conditions and skin structure infections, such as cellulitis, folliculitis, carbuncles, and furuncles. Because of their consistent use, utility, and availability, antibiotics are susceptible to overuse within the medical practice, and, specific to this discussion, in the dermatologic setting. The issue of continuously increasing risk of antibiotic resistance remains an important concern to the dermatologist. The scope of this review will be to provide an overview of the common antibiotics used in the dermatologic setting with an emphasis on identifying areas of overuse, reported bacterial resistance, and discussion of clinical management aimed at decreasing antibiotic resistance.

Community-acquired methicillin-resistant Staphylococcus aureus from skin and soft tissue infections (in a sample of Egyptian population): analysis of mec gene and staphylococcal cassette chromosome

BACKGROUND

Staphylococcus aureus has been recognized as an important pathogen associated with inpatients and community infections. Community-acquired methicillin-resistant S. aureus (CA-MRSA) infections commonly present as skin and soft-tissue infections (SSTIs). Treatment often includes incision and drainage with or without adjunctive antibiotics.

OBJECTIVES

This study aimed to identify CA-MRSA infections both phenotypically and genotypically, to determine their spectrum of antibiotic resistance, and to establish the best scheme for molecular distinction between hospital-acquired MRSA (HA-MRSA) and CA-MRSA by staphylococcal cassette chromosome mec (SCCmec) typing and detection of Panton Valentine leukocidin (PVL).

MATERIALS

50 swabs, from skin and soft tissue of infected lesions of outpatients attending the dermatology department of the Medical School, Alexandria University, were collected. Additionally, a nasal swab was taken from every participant.

METHODS

Collection of swabs from the infected skin and soft tissues, followed by laboratory testing to phenotypically and genotypically identify MRSA. Also, nasal swabs were taken from every patient to identify MRSA colonization.

RESULTS

Staphylococcus aureus strains were identified in 38 (76%) of the 50 clinical isolates. 18 (47.37%) out of the 38 S. aureus strains were resistant to oxacillin and cefoxitin discs, were penicillin binding protein 2a (PBP2a) producers, and were initially diagnosed as MRSA. All of the 18 strains were definitively diagnosed as MRSA by mecA gene detection using real time PCR, while only six (33.33%) strains were PVL positive. Using the sets of primers of Zhang et al.: nine (50%) out of the 18 CA-MRSA strains were SCCmec type V, and one (5.56%) was SCCmec type IVc. Then, using the set of primers by Oliveira et al., two (25%) out of the eight untypable MRSA strains were found to be SCCmec type IV, and six (75%) remained untypable.

CONCLUSIONS

CA-MRSA must be considered when treating skin and soft tissue infections, especially in developing countries. Empirical use of agents active against CA-MRSA is warranted for patients presenting with serious SSTIs.

Antibiotic therapy for pediatric community-acquired pneumonia: do we know when, what and for how long to treat?

Community-acquired pneumonia (CAP) is a common cause of morbidity among children in developed countries and accounts for an incidence of 10-40 cases per 1000 children in the first 5 years of life. Given the clinical, social and economic importance of CAP, there is general agreement that prompt and adequate therapy is essential to reduce the impact of the disease. The aim of this discussion paper is to consider critically the available data concerning the treatment of uncomplicated pediatric CAP and to consider when, how and for how long it should be treated. This review has identified the various reasons that make it difficult to establish a rational approach to the treatment of pediatric CAP, including the definition of CAP, the absence of a pediatric CAP severity score, the difficulty of identifying the etiology, limited pharmacokinetic (PK)/pharmacodynamic (PD) studies, the high resistance of the most frequent respiratory pathogens to the most widely used anti-infectious agents and the lack of information concerning the changes in CAP epidemiology following the introduction of new vaccines against respiratory pathogens. More research is clearly required in various areas, such as the etiology of CAP and the reasons for its complications, the better definition of first- and second-line antibiotic therapies (including the doses and duration of parenteral and oral antibiotic treatment), the role of antiviral treatment and on how to follow-up patients with CAP. Finally, further efforts are needed to increase vaccination coverage against respiratory pathogens and to conduct prospective studies of their impact.

European ST80 community-associated methicillin-resistant Staphylococcus aureus orbital cellulitis in a neonate

Background

Methicillin-resistant Staphylococcus aureus is a serious cause of morbidity and mortality in hospital environment, but also, lately, in the community. This case report is, to our knowledge, the first detailed description of a community-associated methicillin-resistant S. aureus ST80 orbital cellulitis in a previously healthy neonate. Possible predisposing factors of microbial acquisition and treatment selection are also discussed.

Case presentation

A 28-day-old Caucasian boy was referred to our hospital with the diagnosis of right orbital cellulitis. His symptoms included right eye proptosis, periocular edema and redness. Empirical therapy of intravenous daptomycin, rifampin and ceftriaxone was initiated. The culture of pus yielded a methicillin-resistant S. aureus isolate and the molecular analysis revealed that it was a Panton-Valentine leukocidine-positive ST80 strain. The combination antimicrobial therapy was continued for 42 days and the infection was successfully controlled.

Conclusions

Clinicians should be aware that young infants, even without any predisposing condition, are susceptible to orbital cellulitis caused by community-associated methicillin-resistant S. aureus. Prompt initiation of the appropriate empirical therapy, according to the local epidemiology, should successfully address the infection, preventing ocular and systemic complications.

NVC-422 topical gel for the treatment of impetigo

Impetigo is a highly contagious bacterial skin infection affecting children worldwide that is caused by the Gram-positive bacteria Staphylococcus aureus, Streptococcus pyogenes, or both. Staphylococcus species can quickly develop drug resistance rendering mupirocin, fusidic acid, and erythromycin ineffective. Preclinical and clinical studies demonstrated that NVC-422 (N, N-dichloro-2, 2-dimethyltaurine) rapidly kills pathogens without the development of drug resistance. 129 patients with clinically diagnosed impetigo were randomized to three dose groups (0.1, 0.5, or 1.5% NVC-422 topical gel) in a study conducted at 2 centers; 125 patients (97%) had microbiologically confirmed infection. Treatment was administered three times a day (TID) for 7 days to all randomized subjects. Response was measured at the completion of treatment (Day 8) and 1 week post treatment (Day 15) by the Skin Infection Rating Scale (SIRS) and by microbiological response. A total of 120 subjects (96%) completed all 7 days of treatment and were assessed at end of treatment (EOT). Clinical response rate at EOT in the PPC population was excellent in each of the dose groups (84.6%, 87.2%, and 92.3% in the 0.1%, 0.5% and 1.5% dose groups respectively). The majority of the infections were caused by S. aureus, alone (106/125, 85%) of which approximately 10% were MRSA. There were no clinical recurrences in any treatment groups. Treatment-emergent adverse events were seen in 5.4% of the subjects (7/129) and were mild to moderate and resolved. NVC-422 topical gel administered TID was well tolerated, with high rates of clinical and microbiological responses for treating impetigo.

Population biology of Gram-positive pathogens: high-risk clones for dissemination of antibiotic resistance

Infections caused by multiresistant Gram-positive bacteria represent a major health burden in the community as well as in hospitalized patients. Staphylococcus aureus, Enterococcus faecalis and Enterococcus faecium are well-known pathogens of hospitalized patients, frequently linked with resistance against multiple antibiotics, compromising effective therapy. Streptococcus pneumoniae and Streptococcus pyogenes are important pathogens in the community and S. aureus has recently emerged as an important community-acquired pathogen. Population genetic studies reveal that recombination prevails as a driving force of genetic diversity in E. faecium, E. faecalis, S. pneumoniae and S. pyogenes, and thus, these species are weakly clonal. Although recombination has a relatively modest role driving the genetic variation of the core genome of S. aureus, the horizontal acquisition of resistance and virulence genes plays a key role in the emergence of new clinically relevant clones in this species. In this review, we discuss the population genetics of E. faecium, E. faecalis, S. pneumoniae, S. pyogenes and S. aureus. Knowledge of the population structure of these pathogens is not only highly relevant for (molecular) epidemiological research but also for identifying the genetic variation that underlies changes in clinical behaviour, to improve our understanding of the pathogenic behaviour of particular clones and to identify novel targets for vaccines or immunotherapy.