Novel antibacterial agents for skin and skin structure infections

In silico Prediction of Skin Sensitization: Quo vadis?

Skin direct contact with chemical or physical substances is predisposed to allergic contact dermatitis (ACD), producing various allergic reactions, namely rash, blister, or itchy, in the contacted skin area. ACD can be triggered by various extremely complicated adverse outcome pathways (AOPs) remains to be causal for biosafety warrant. As such, commercial products such as ointments or cosmetics can fulfill the topically safe requirements in animal and non-animal models including allergy. Europe, nevertheless, has banned animal tests for the safety evaluations of cosmetic ingredients since 2013, followed by other countries. A variety of non-animal in vitro tests addressing different key events of the AOP, the direct peptide reactivity assay (DPRA), KeratinoSens™, LuSens and human cell line activation test h-CLAT and U-SENS™ have been developed and were adopted in OECD test guideline to identify the skin sensitizers. Other methods, such as the SENS-IS are not yet fully validated and regulatorily accepted. A broad spectrum of in silico models, alternatively, to predict skin sensitization have emerged based on various animal and non-animal data using assorted modeling schemes. In this article, we extensively summarize a number of skin sensitization predictive models that can be used in the biopharmaceutics and cosmeceuticals industries as well as their future perspectives, and the underlined challenges are also discussed.

Moxifloxacin-associated neutropenia

A 32-y-old woman presented with pneumonia. Treatment was started with moxifloxacin. On day 2 of moxifloxacin treatment the patient developed neutropenia. After discontinuing the moxifloxacin, neutrophil counts were normal on day 4. Clinicians should be aware of the possibility of this adverse effect in patients treated with moxifloxacin.

Synthesis, structures and antibacterial activities of benzoylthiourea derivatives and their complexes with cobalt

Four new thiocarbonyl fluorobenzamides and their complexes with cobalt have been synthesized and characterized by elemental analysis, FTIR, and (1)H NMR. Five crystal structures of the thioylbenzamides complexes of Co(PTCB)(3), Co(2FPTCB)(3), Co(4FPTCB)(3), Co(2FMTCB)(2) and Co(4FMTCB)(3) have been determined by X-ray diffraction. The antibacterial properties of these compounds against the bacteria, E. coli, Staphylococcus aureus, B. subtilis, P. aeruginosa, and Shewanella sp. were investigated. The experiments showed that both compounds and the complexes had the antibacterial activities against all of the studied bacteria. The thioylbenzamides had stronger controls for the bacteria of E. coli, S. aureus, B. subtilis and P. aeruginosa than their corresponding cobalt complexes. There was the contrary result against the bacteria of Shewanella sp. The para-substitution of fluorine atom increased antibacterial activities, while fluorine atom was substituted on ortho-benzoyl, the antibacterial activity weakened. The thioylbenzamides linked to piperidine instead of a morpholine group may increase the antibacterial activities.

Pyodermitis

Pyodermitis are primary skin infections mainly caused by pyogenic bacteria of the Staphylococcus and Streptococcus genera. They are relatively common diseases that affect adults and children. There have been frequent reports of bacterial resistance to the recommended antibiotics over the last few years; however, new substances are in use or under development, and this represents an evolution in the treatment of pyodermitis. This review aims at describing clinical, diagnostic and therapeutical features of major pyodermitis: impetigo, ecthyma, erysipelas, staphylococcal scalded skin syndrome and folliculitis.

Theoretical considerations and modeling of chemical inactivation of microorganisms: inactivation of Giardia Cysts by free chlorine

Chemical inactivation of microorganisms is a common process widely employed in many fields such as in treatment of water, preservation in food industry and antimicrobial treatments in healthcare. For economy of applications and efficiency of treatment establishment the minimum dosage of breakpoint in the chemical application becomes essential. Even though experimental investigations have been extensive, theoretical understanding of such processes are demanding. Commonly employed theoretical analyses for the inactivation of microorganisms and depletion of chemicals include kinetics expressing the rates of depletion of chemical and microorganisms. The terms chemical demand (x) and specific disinfectant demand (alpha) are often used in theoretical modeling of inactivation. The value of specific disinfectant demand (alpha) has always been assumed to be a constant in these models. Intracellular concentration built up within the cells of the microorganisms during inactivation could lead to possible weakening effects of microorganisms thereby requiring lower doses as disinfection proceeds makes the assumption of constant alpha inaccurate. Model equations are formulated based on these observations co-relating the parameters alpha and x with a progressive inactivation (N/N(0)). The chemical concentration (C) is also presented in terms of the inactivation time (t) and the survival ratio (N/N(0)) for given pH and temperature conditions. The model is examined using experimentally verified Ct data of Giardia Cysts/chlorine system. The respective values of x for different survival ratios were evaluated from the data using MatLab software. Proposed model correlating for the disinfectant demand (x) with the survival ratio (N/N(0)) fits satisfactorily with those evaluated from data. The rate constants for different pH and temperature conditions are evaluated which showed compatibility with the Arrhenius model. The dependence of frequency factors with pH indicated compatibility with accepted models. The Ct values regenerated with the kinetic data shows a very accurate fit with published data.

Antibiotic considerations in the treatment of multidrug-resistant (MDR) pathogens: a case-based review

The recent rise in antimicrobial resistance among health-care associated pathogens is a growing public health concern. According to the National Nosocomial Infections Surveillance System, rates of methicillin-resistant Staphylococcus aureus (MRSA) in intensive care units have nearly doubled over the last decade. Of equal importance, gram-negative agents such as Pseudomonas aeruginosa, Acinetobacter baumannii, and extended-spectrum beta lactamase-producing Enterobacteriaceae demonstrate increasing resistance to third-generation cephalosporins, fluoroquinolones, and, in some cases, carbapenems. As a consequence, hospitalists may find themselves utilizing new antibiotics in the treatment of bacterial infections. This case-based review will highlight 8 antibiotics that have emerging clinical indications in treating these multidrug-resistant (MDR) pathogens.

Current options for the treatment of impetigo in children

Impetigo contagiosa is a common, superficial, bacterial infection of the skin characterised by an inflamed and infected epidermis caused by Staphylococcus aureus, Streptococcus pyogenes or both. The less common bullous impetigo is characterised by fragile fluid-filled vesicles and flaccid blisters, and is invariably caused by pathogenic strains of S. aureus. In bullous impetigo, exfoliative toxins are produced, although these are restricted to the area of infection and bacteria can be cultured from the blister contents. In the rare variant, staphylococcal scalded skin syndrome, the exfoliative toxins are spread haematogenously from a localised source causing widespread epidermal damage at distant sites.

Children hospitalized with skin and soft tissue infections: a guide to antibacterial selection and treatment

Skin and soft tissue infections in children are an important cause for hospitalization. A thorough history and physical examination can provide clues to the pathogens involved. Collection of purulent discharge from lesions should be completed prior to initiating antimicrobial therapy, and results of bacteriologic studies (Gram stain and culture) should guide therapeutic decisions. The main pathogens involved in these infections are Staphylococcus aureus and group A beta-hemolytic streptococci, but enteric organisms also play a role especially in nosocomial infections. Increasing antibacterial resistance is becoming a major problem in the treatment of these infections worldwide. Specifically, the rise of methicillin-resistant S. aureus and glycopeptide-resistant S. aureus pose challenges for the future. Infections of the skin and soft tissues can be broadly classified based on the extent of tissue involvement. Superficial infections such as erysipelas, cellulitis, bullous impetigo, bite infections, and periorbital cellulitis may require hospitalization and parenteral antibacterials. Deeper infections such as orbital cellulitis, necrotizing fasciitis, and pyomyositis require surgical intervention as well as parenteral antibacterial therapy. Surgery plays a key role in the treatment of abscesses and for the debridement of necrotic tissue in deep infections. Intravenous immunoglobulin, as an adjunctive therapy, can be helpful in treating necrotizing fasciitis. For most infections an antistaphylococcal beta-lactam antibacterial is first-line therapy. Third-generation cephalosporins and beta-lactam/beta-lactamase inhibitor antibacterials as well as clindamycin or metronidazole are often required to provide broad-spectrum coverage for polymicrobial infections.Special populations, such as immunocompromised children, those with an allergy to penicillins, and those that acquire infections in hospitals, require specific antibacterial strategies. These usually involve broader antimicrobial coverage with increased Gram-negative (including antipseudomonal) and anerobic coverage. In patients with a true allergy to penicillins, clindamycin and vancomycin play an important role in treating Gram-positive infections. Newer antibacterial agents, such as linezolid and quinupristin/dalfopristin, are increasingly being studied in children for the treatment of skin and soft tissue infections. These agents hold promise for the future especially in the treatment of highly resistant, Gram-positive organisms such as methicillin-resistant S. aureus, vancomycin-resistant S. aureus, and vancomycin-resistant enterococci.

Community-Acquired Methicillin Resistant Staphylococcus aureus Skin Infection

Staphylococcus aureus is one of the most common pathogens in skin and soft tissue infections, as well as in potentially serious nosocomial infections in patients who acquire it when hospitalized. Penicillin was introduced in the 1940's as an effective treatment against S. aureus. However, shortly after penicillin's introduction, penicillin resistance to S. aureus emerged due to a plasmid-mediated beta-lactamase enzyme. In 1959, a semisynthetic penicillin, methicillin was introduced to overcome the resistance problem. However, within a year, bacteria resistant to methicillin and other penicillinase stable beta-lactams, were present. Worldwide emergence of methicillin-resistant S aureus (MRSA) was established by the 1980's. Since that time, MRSA has become widespread in hospitals and long-term care facilities around the world, accounting for numerous nosocomial infections. Recently, there has been an alarming increase in the incidence of community-acquired MRSA (CA-MRSA). Patients with CA-MRSA began to be reported in the early 1990's and its prevalence has continued to increase. This paper summarizes the current information known about CA-MRSA as it relates to skin infections including populations at risk, clinical presentation, and treatment options.

Antimicrobial therapy in Dermatology

The extensive and sometimes indiscriminate use of antibiotics sometimes without strict indications has led to increases in both bacterial resistance and sensitization of patients. Systemic antibiotics in skin infections are indicated when a severe local infection occurs which spreads into the surrounding tissue or when there are signs of systemic infection. There are special indications in patients with peripheral arterial occlusive disease,diabetes or immunosuppression. Topical use of antibiotics should be abandoned and replaced by antiseptics. The beta-lactam antibiotics are the antibiotics of first choice for many skin infections. They are usually effective, have a well-defined profile of adverse events and most are affordable. Penicillin G or V are the first line treatment for erysipelas. Infections with Staphylococcus aureus are usually treated with isoxazolyl penicillins or second generation cephalosporins. In mixed infections in patients with diabetes or peripheral arterial occlusive disease,the treatment of choice is metronidazole plus beta-lactam-/beta-lactamase inhibitor antibiotics, but quinolones or second generation cephalosporins can also be used, once again with metronidazole. The aim of this review is to define the indications for antibiotics in dermatology, to highlight their modes of action and adverse effects and to make suggestions for rational antibiotic therapy in cutaneous infections frequently encountered in the practice of dermatology.

Gram-positive resistance: pathogens, implications, and treatment options: insights from the Society of Infectious Diseases Pharmacists

Despite the advent of new antibiotics, resistance in gram-positive pathogens, including staphylococci and enterococci, continues to increase. This is evident with the recent emergence of vancomycin-resistant Staphylococcus aureus . Newer treatment agents are available, including quinupristin-dalfopristin, linezolid, and daptomycin. In addition, investigational agents are being explored. Clinical trials have been conducted for various infections, such as skin and skin structure infections, pneumonia, and bloodstream infections. Antibacterial activity, site of infection, and potential for adverse effects must be taken into account when making decisions regarding therapy.

Recently approved and investigational antibiotics for treatment of severe infections caused by Gram-positive bacteria

The development of resistance in the major pathogenic Gram-positive genera Staphylococcus and Streptococccus has led to the need for new agents that are able to overcome existing resistance mechanisms or that have novel mechanisms of action. There is currently a dearth of new agents that are active against resistant bacterial species. Agents that have recently been approved for clinical use include linezolid, the first oxazolidinone in clinical use, daptomycin, the first lipopeptide in clinical use, and telithromycin, a ketolide that is derived from clarithromycin. Agents currently in clinical development include tigecycline, a broad-spectrum intravenous tetracycline, ceftobiprole, a broad-spectrum cephalosporin that has activity against methicillin-resistant staphylococci, DX-619 and WCK-771, which are potent quinolones that have activity against quinolone-resistant staphylococci, oritavancin and dalbavancin, both of which are new glycopeptides, and iclaprim, which is a diaminopyrimidine. Additional agents that are in preclinical development against Gram-positive pathogens include quinoline-naphthyridine agents, which target novel DNA gyrase sites, other novel quinolones that have high potency, peptide deformylase inhibitors, and new lincosamide, oxazolidinone, lipopeptide and cephalosporin derivatives. Misuse of potent new agents will, however, result in the inevitable development of resistance to these agents; responsible use of potent new agents is required to prevent continuation of this vicious cycle.

Antimicrobial Management of Complicated Skin and Skin Structure Infections in the Era of Emerging Resistance

BACKGROUND

Complicated skin and skin structure infections (cSSSIs) are among the most common infections treated in the hospital setting. The mainstays of treatment continue to be antimicrobial therapy combined with appropriate surgical intervention. Due to increasing resistance among pathogens commonly implicated in cSSSIs, the objectives of this review were to describe the potential pathogens causing skin infections, the implications of resistance to currently used drug therapy, and the role of new antibiotics with activity for pathogens causing cSSSIs.

METHODS

Relevant information from the primary literature and review articles were identified through a MEDLINE search of the medical literature (1980 to the present) using the terms abscess, wound infection, skin and skin structure infection, antibiotics, resistance, quinupristin- dalfopristin, linezolid, daptomycin, tigecycline, oritavancin, and dalbavancin. Meeting posters and slides were identified from the Interscience Conference of Antimicrobial Agents and Chemotherapy (1998-2004) for supplemental data.

RESULTS

The most commonly implicated pathogens in cSSSIs include gram-positive bacteria, specifically Staphylococcus aureus. Gram-negative and mixed organisms are additionally encountered in serious cSSSI. Antimicrobial resistance among both gram-positive and gramnegative bacteria has increased significantly during the last decade, with methicillin resistance among S. aureus approaching 60% in hospitals and becoming more frequent in the community as well. As a result, resistance is the driving factor for treatment failure and rising costs for infection management. Few antimicrobial agents are available currently to treat resistant bacteria in cSSSIs; vancomycin is currently the drug of choice against resistant grampositive cocci; however, resistance to this agent has appeared in enterococci and S. aureus. Several new antibiotics such as linezolid and daptomycin are now available for the management of cSSSIs. Other agents such as tigecycline are under investigation and should be available soon to increase treatment options for cSSSIs caused by resistant bacteria.

CONCLUSIONS

Although the resistance of cSSSI pathogens is problematic, new antibiotics with broad-spectrum activity against resistant gram-positive and gram-negative bacteria are promising for the management of severe cSSSIs.

Current use of anti-infectives in dermatology

Dermatologic diseases encompass a broad category of pathologic situations. Infection remains a significant aspect of the pathology faced in patient encounters, and it is natural to expect that anti-infectives play a major element in the armamentarium utilized by dermatologists. Aside from the treatment of the classic bacterial and fungal infections, there are now new uses for antiviral agents to help suppress recurrent disease, such as herpes simplex. There is also the novel approach of using anti-infectives, or agents that have been thought to have antimicrobial activity, to treat inflammatory diseases. This review describes anti-infectives, beginning with common antibiotics used to treat bacterial infections. The discussion will then cover the current use of antivirals. Finally, the description of antifungals will be separated, starting with the oral agents and ending with the topical antimycotics. The use of anti-infectives in tropical dermatology has been purposefully left out, and perhaps should be the subject of a separate review. Cutaneous bacterial infections consist chiefly of those microorganisms that colonize the skin, such as species of staphylococcus and streptococcus. Propionibacterium acnes and certain other anaerobes can be involved in folliculitis, pyodermas and in chronic conditions such as hidradenitis suppurativa.

What's New in Antibiotics?

Antibiotics are important agents in dermatologic practice. New drugs have expanded the therapeutic approach to uncomplicated skin infections and complicated infections involving deeper soft tissue or infections that require surgical intervention. This article reviews new antibiotics of dermatologic importance, including daptomycin (cyclic lipopeptide), linezolid (oxazolidinone), quinupristin-dalfopristin (streptogramins), moxifloxacin and gatifloxacin (fluoroquinolones), and dalbavancin and oritavancin, which are presently under investigation.

Therapy of other bacterial infections

Cutaneous bacterial disease continues to account for a significant proportion of clinical visits. The continuing emergence of strains that are resistant to available antibacterial agents creates a challenge for dermatologists, who need to keep abreast of current treatment strategies. In this article, antibacterial regimens are presented for skin infections caused by organisms such as Staphylococcus, Streptococcus, Pseudomonas, Neisseria, Haemophilus ducreyi, Treponema pallidum, Bacillus anthracis, Yersinia pestis, Pasteurella multocida, Vibrio vulnificus, Actinomyces, and Nocardia.

Treatment of bullous impetigo and the staphylococcal scalded skin syndrome in infants

Impetigo is a common, superficial, bacterial infection of the skin characterized by an inflamed and infected epidermis. The rarer variant, bullous impetigo, is characterized by fragile fluid-filled vesicles and flaccid blisters and is invariably caused by pathogenic strains of Staphylococcus aureus. Bullous impetigo is at the mild end of a spectrum of blistering skin diseases caused by a staphylococcal exfoliative toxin that, at the other extreme, is represented by widespread painful blistering and superficial denudation (the staphylococcal scalded skin syndrome). In bullous impetigo, the exfoliative toxins are restricted to the area of infection, and bacteria can be cultured from the blister contents. In staphylococcal scalded skin syndrome the exfoliative toxins are spread hematogenously from a localized source causing widespread epidermal damage at distant sites. Both occur more commonly in children under 5 years of age and particularly in neonates. It is important to swab the skin for bacteriological confirmation and antibiotic sensitivities and, in the case of staphylococcal scalded skin syndrome, to identify the primary focus of infection. Topical therapy should constitute either fusidic acid (Fucidin, Leo Pharma Ltd) as a first-line treatment, or mupirocin (Bactroban, GlaxoSmithKline) in proven cases of bacterial resistance. First-line systemic therapy is oral or intravenous flucloxacillin (Floxapen, GlaxoSmithKline). Nasal swabs from the patient and immediate relatives should be performed to identify asymptomatic nasal carriers of Staphylococcus aureus. In the case of outbreaks on wards and in nurseries, healthcare professionals should also be swabbed.