Efficacy of a silicone urinary catheter impregnated with chlorhexidine and triclosan against colonization with Proteus mirabilis and other uropathogens

We sought to develop an infection-resistant urinary catheter. We evaluated 3 types of catheters for their efficacy against uropathogens in an in vitro model of the urinary tract. The catheter impregnated with chlorhexidine and triclosan suppressed the growth of uropathogens, including Proteus mirabilis, for 20-30 days or longer.

Inguinal site infection as a rare cause of secondary peritonitis: report of a case

BACKGROUND

Many rare conditions may cause secondary peritonitis. Injection site infection as a primary source of peritonitis has not been reported.

METHODS

Case report and review of the pertinent English-language literature.

RESULTS

We describe a 39-year-old intravenous drug user who presented with peritonitis. During the surgical exploration, all abdominal organs were intact, but there was an orifice in the pelvic peritoneum that was related to an inguinal site infection. Cultures of both the inguinal area and the peritoneal cavity discharge revealed Staphylococcus aureus.

CONCLUSIONS

Physicians should be aware of secondary peritonitis induced by self-injection of illicit substances in proximity to the peritoneal envelope.

Anti-MRSA beta-lactams in development, with a focus on ceftobiprole: the first anti-MRSA beta-lactam to demonstrate clinical efficacy

Ceftobiprole is the first of the investigational beta-lactam antibiotics with in vitro activity against methicillin-resistant staphylococci to reach and complete Phase III therapeutic trials. Its antibacterial spectrum includes methicillin-resistant Staphylococcus aureus (MRSA), Enterococcus faecalis, penicillin-resistant streptococci and many Gram-negative pathogens. It has demonstrated in vivo activity against many experimental infections caused by these pathogens. Ceftobiprole has completed Phase III clinical trials for complicated skin and skin structure infections, is being studied in Phase III pneumonia trials and has demonstrated non-inferiority compared with vancomycin in a Phase III complicated skin and skin structure infections trial, resulting in > 90% clinical cures of infections caused by MRSA. Other anti-MRSA beta-lactams in therapeutic clinical trials include the carbapenem CS-023/RO-4908463 and the cephalosporin ceftaroline (PPI-0903). The future of all of these agents will depend on their clinical efficacy, safety and their ability to be accepted as beta-lactams for the reliable treatment of a broad spectrum of infections, including those caused by MRSA.

Usefulness of teicoplanin for preventing methicillin-resistant Staphylococcus aureus infections in orthopedic surgery

In order to gather more data on the use of teicoplanin for reducing MRSA infections in high-risk populations, the present study was conducted. At a hospital in Barcelona, Spain, there was a high prevalence of MRSA infections among patients who underwent surgery for femoral neck fracture during the first 5 months of 2002 (period A) when cefuroxime was the antibiotic prophylaxis. During the following 12 months (period B) 600 mg of teicoplanin was added to cefuroxime. The rates of overall and MRSA infection during period A were 5.07 and 2.73%, respectively. Pulsed-field gel electrophoresis demonstrated there was no clonal relationship among MRSA strains. No nasal carriers of MRSA were detected among health workers. During period B the rates of overall and MRSA infection were 2.36 and 0.19%, respectively. Both rates were statistically significantly lower than those in period A (p<0.05). These results suggest teicoplanin may be useful in patients undergoing orthopedic surgery when the prevalence of MRSA is high.

Induced production of emericellamides A and B from the marine-derived fungus Emericella sp. in competing co-culture

Induction of the production of emericellamides A and B (1, 2), by the marine-derived fungus Emericella sp., was observed during co-culture with the marine actinomycete Salinispora arenicola. The planar structures of these new cyclic depsipeptides, which incorporate 3-hydroxy-2,4-dimethyldecanoic acid and 3-hydroxy-2,4,6-trimethyldodecanoic acid, were assigned by combined chemical and spectral methods. The absolute configurations of the amino acids, and those of the chiral centers on the side chain, were established by application of the Marfey's method, by J-based configuration analysis, and by application of the modified Mosher method. Emericellamides A and B show modest antibacterial activities against methicillin-resistant Staphylococcus aureus with MIC values of 3.8 and 6.0 microM, respectively.

Acute bacterial skin infections and cellulitis

PURPOSE OF REVIEW

Acute bacterial skin infections are very common, with various presentations and severity. This review focuses on deep skin infections. We separate acute nonnecrotizing infections of the hypodermis (erysipelas), forms with abscesses or exudates and necrotizing fasciitis. These three types actually differ in risk factors, bacteriology, treatment and prognosis.

RECENT FINDINGS

Leg erysipelas/cellulitis occurs in more than one person/1000/year. It remains mainly due to streptococci. Foot intertrigo is an important risk factor. Necrotizing fasciitis is much rarer and usually occurs in patients with chronic diseases. Staphylococci, especially community-acquired methicillin-resistant strains in some areas, play a growing role in the intermediate form of cellulitis with abscesses and exudates. For erysipelas or noncomplicated cellulitis, antibiotic treatment at home, when feasible, is much less expensive and as effective as hospital treatment. Intermediate cases with collections and exudates often require surgical drainage. For necrotizing fasciitis early surgery remains essential in order to decrease the mortality rate.

SUMMARY

Antibiotic treatment of deep skin infections must be active on streptococci; the choice of a larger spectrum of activity depends on clinical presentation, risk factors and the burden of methicillin-resistant staphylococci in the environment.

Spread of a single multiresistant methicillin-resistant Staphylococcus aureus clone carrying a variant of staphylococcal cassette chromosome mec type III isolated in a university hospital

The purpose of the study was the molecular characterization of methicillin-resistant Staphylococcus aureus (MRSA) isolates cultured from patients treated in seven wards of a university hospital in Lublin, Poland, over a 14-month period. Eleven nosocomial MRSA isolates were analyzed. Phenotypic identification of the isolates as MRSA was confirmed by the detection of the nuc and mecA genes using a multiplex PCR assay. The MRSA isolates were further characterized by pulsed-field gel electrophoresis, 16S-23S rRNA spacer length polymorphism analysis, and the simplex and multiplex SCCmec PCR assays. The MRSA isolates were found to be multiresistant: in addition to resistance to beta-lactam agents, they demonstrated resistance to ciprofloxacin, tetracycline, erythromycin, and gentamicin. The MRSA isolates were genetically identical and shared common pulsed-field gel electrophoresis profiles and 16S-23S rRNA spacer length polymorphism profiles. The PCR-based method revealed that the profile of the Lublin clone was identical to that of the Brazilian pandemic MRSA isolates. By SCCmec typing, all MRSA isolates harbored the C variant of the SCCmec type III that differed from the typical SCCmec type III pattern by the lack of locus F (414 bp). The results of this study indicate the spread of a single, multiresistant, MRSA clone in various wards of a university hospital over a 14-month period. The SCCmec structure harbored by the Lublin clone has previously been identified among Polish MRSA isolates representing the HoMRSA-Pol1 clone. The data from this study indicate that the Lublin MRSA clone is most probably genetically related to the HoMRSA-Pol1 clone. Moreover, this latter clone belongs to ST239, the same sequence type as the Hungarian and Brazilian pandemic MRSA isolates.

Comparison of cefoxitin and moxalactam 30 µg disc diffusion methods for detection of methicillin resistance in coagulase-negative staphylococci

OBJECTIVES

To compare cefoxitin and/or moxalactam 30 microg disc diffusion (DD) methods to detect methicillin resistance in coagulase-negative staphylococci (CoNS) using both high- and low-density (HD/LD) inoculum techniques.

METHODS

A challenge set of 192 CoNS was tested. DD test results were compared with PBP2a detection.

RESULTS

With the LD inoculum, the sensitivity/specificity of cefoxitin and moxalactam were 94.4%/100% and 100%/92.4%, respectively, using the DD breakpoints of the Comité de l'Antibiogramme de la Société Française de Microbiologie. With the HD inoculum, the sensitivity/specificity of cefoxitin and moxalactam were 93.7%/100% and 100%/96.9%, using the cefoxitin DD breakpoints of the CLSI and a resistant/susceptible breakpoint of < 20 mm/>or=20 mm for moxalactam. Comparison of receiver operating characteristic AUCs did not show significant difference between studied assays, but the overlapping zone where both PBP2a-positive and PBP2a-negative isolates were observed concerned a lower number of strains with moxalactam than with cefoxitin (P < 0.001). Combination of cefoxitin and moxalactam DD methods demonstrated that all isolates with a concordant cefoxitin/moxalactam phenotype were correctly classified. Interestingly, all isolates misclassified by each DD method used alone were cefoxitin-susceptible and moxalactam-resistant.

CONCLUSIONS

Although all DD methods studied here performed well for detecting methicillin resistance in CoNS, moxalactam had a higher accuracy than cefoxitin to differentiate heteroresistant isolates from PBP2a-negative strains. Identification of isolates that should be submitted to a confirmatory test to conclude on methicillin resistance can be easily obtained by combining cefoxitin and moxalactam DD methods.

Semisynthetic approaches to laspartomycin analogues

Laspartomycin C (1), a lipopeptide antibiotic related to amphomycin, consists of a cyclic peptide core and an aspartic acid unit external to the core and linking this to a C15-2,3-unsaturated fatty acid. This was reported initially to be active against Staphylococcus aureus, and more recent studies have shown that it is active against VRE, VISA, and MRSA isolates. The enzymatic cleavage of the fatty acid tail was accomplished with a deacylase produced by Actinoplanes utahensis and resulted in two peptides, designated Peptide 1 and Peptide 2. Semisynthetic derivatives of both peptides have been made, and the principal requirement for biological activity appears to be the presence of an acylaspartic acid.

Successful decolonization of meticillin-resistant Staphylococcus aureus in paediatric patients with cystic fibrosis (CF) using a three-step protocol

Methicillin-resistant Staphylococcus aureus (MRSA) is recognized as a bacterial pathogen in patients with cystic fibrosis (CF) although its clinical effects can be variable. The aim of this study was to evaluate the efficacy of a three-step decolonization protocol for MRSA (Belfast CF MRSA decolonization protocol). Of the 17 paediatric patients treated during the five years of the study, eight (47%) were successfully decolonized following one five-day course of oral rifampicin and fusidic acid. The success rate increased to 12 (71%) patients after a second five-day oral treatment course in the 11 patients who remained culture positive at the end of the first treatment cycle. In a further four patients, clearance was achieved with a course of intravenous teicoplanin, increasing the decolonization rate to 16 of 17 patients (94%). These results compare favourably with other published studies and show that MRSA decolonization can be successful in a high proportion of paediatric CF patients.

Oral β-lactams applied to uncomplicated infections of skin and skin structures

Uncomplicated skin and skin structure infections (uSSSIs) include impetigo, erysipelas, folliculitis, simple abscesses, and cellulitis. Their common bacterial causative agents include Staphylococcus aureus and Streptococcus pyogenes. Current guidelines predate the widespread occurrences of methicillin-resistant S. aureus (MRSA) as a community-acquired pathogen and include dicloxacillin, cephalexin, erythromycin, clindamycin, and amoxicillin/clavulanic acid, all orally, or mupirocin ointment applied topically, for impetigo. For other uSSSI, recommendations are based on the probability of the infection being caused by MRSA. If methicillin-susceptible S. aureus (MSSA) are known or suspected, the oral agents recommended include clindamycin, dicloxacillin, cephalexin, doxycycline, minocycline, and trimethoprim-sulfamethoxazole (SXT). For MRSA, recommended oral agents are linezolid, clindamycin, doxycycline, minocycline, and SXT. Because community-acquired MRSA infections now predominate in patients with abscesses in the United States, agents recommended for MRSA should be used for this indication. Local susceptibility patterns should guide empiric therapy. However, no placebo-controlled trials of uSSSI are available, and the evidence used to generate these recommendations is based on comparative noninferiority studies, often with wide noninferiority margins and confidence intervals. The evidence used in developing current guidelines therefore has significant limitations. Further studies, such as superiority outcome studies, placebo-controlled studies, measurement of time to resolution, or other novel approaches, are needed to resolve these treatment dilemmas. Until such studies are performed, the best surrogate available for predicting clinical outcome is application of pharmacokinetic and pharmacodynamic principles; these describe in vivo drug behavior and allow determination of susceptibility breakpoints for predicting in vivo antimicrobial efficacy via attainment of antimicrobial targets.

A new class of anti-MRSA and anti-VRE agents: Preparation and antibacterial activities of indole-containing compounds

A new class of indole-containing compounds were prepared by the use of three component reaction and their in vitro antibacterial activities (MIC) were evaluated against Staphylococcus aureus and Enterococcus faecium including MRSA and VRE.

Antimicrobial activity of hydrophobic xanthones from Cudrania cochinchinensis against Bacillus subtilis and methicillin-resistant Staphylococcus aureus

Ten xanthones with one or two isoprenoid groups and a prenylated benzophenone isolated from roots of Cudrania cochinchinensis (Moraceae) were tested for their antimicrobial activities against Bacillus subtilis and methicillin-resistant Staphylococcus aureus (MRSA). Among these compounds, gerontoxanthone H exhibited considerable antibacterial activity against B. subtilis (MIC = 1.56 microg/ml). Four xanthones, gerontoxanthone I, toxyloxanthone C, cudraxanthone S, and 1,3,7-trihydroxy-2-prenylxanthone, showed weak antibacterial activity against the bacterium (MICs = 3.13-6.25 microg/ml). These compounds also exhibited similar MIC values against methicillin-sensitive S. aureus, MRSAs, and Micrococcus luteus.

An outbreak of catalase-negative methicillin-resistant Staphylococcus aureus

The wide dissemination of a major epidemic methicillin-resistant Staphylococcus aureus (MRSA) clone in Brazilian hospitals (Brazilian clone) limits the value of molecular typing techniques such as pulsed-field gel electrophoresis (PFGE) for outbreak investigation. We report the first outbreak of a catalase-negative strain of MRSA, which was initially detected by the unusual result of this phenotypical test. The outbreak occurred in the Hospital Sanatorinhos de Carapicuíba, a 237-bed secondary hospital located in São Paulo, Brazil. From May to August 2002, a total of 11 MRSA isolates were recovered from four patients in the intensive care unit. All the isolates were catalase negative and susceptible only to vancomycin and linezolid. Three of the four patients eventually died. Molecular typing demonstrated an indistinguishable PFGE pattern among the 11 isolates, with similarities to the Brazilian clone and the hospital's usual MRSA strain. This report emphasizes the importance of an uncommon phenotypical result as a marker for initiating an outbreak investigation and should encourage clinical laboratories to recognize and report such isolates.

Synthesis of a novel inhibitor against MRSA and VRE: Preparation from zerumbone ring opening material showing histidine-kinase inhibition

Zerumbone ring-opening derivative 2 inhibited autophosphorylation of the essential histidine protein kinase (HPK), YycG, existing in Bacillus subtilis constituting a two-component system (TCS). However, it did not inhibit drug-resistant bacterium such as MRSA and VRE. Tryptophan derivative 34 also could be regulated by a TCS system like 2. In addition, 34 showed good inhibition against MRSA and VRE.

Heterosexual transmission of community-associated methicillin-resistant Staphylococcus aureus

Heterosexual transmission of community-associated methicillin-resistant Staphylococcus aureus has not been documented. As part of a survey conducted in northern Manhattan, we encountered 3 households in which heterosexual transmission was responsible for new community-associated methicillin-resistant S. aureus infection. The vaginal and inguinal isolates obtained from the sexual partners were USA 300. This report documents an important and previously unrecognized means of community-associated methicillin-resistant S. aureus colonization and transmission for these potentially invasive strains.

[Study on activity of antistaphylococcal antibiotic batumin against methicillin resistant strains of staphylococci]

A stable increase in the frequency of methicillin resistant clinical isolates of staphylococci was recorded. 258 strains of Staphylococcus aureus and S. epidermidis, including methicillin resistant ones, were susceptible to batumin. The minimum inhibitory concentration of batumin ranged within 0.04 and 0.5 mcg/ml and depended on the concentration of the microbial cells and the medium pH. The medium composition had limited influence on the batumin activity. No differences in the batumin activity against methicillin susceptible and methicillin resistant staphylococci were observed. The antibiotic had bactericidal action on the strains (2-4 mcg / ml). The results of the study showed that batumin ointment was prospective for eradication of S. aureus. including MRSA, in cases with the nasal carriage and for control of multiresistant strains during hospital outbreaks.

Isolated bacteria and drug susceptibility associated with the course of surgical site infections

Bacterial culture is not often performed for mild surgical site infections, so only isolates from patients with severe surgical site infections have been identified. Consequently, broad-spectrum antibacterials, such as carbapenems, whose resistance has been highly modified, have been selected for use from the initial stage of these infections, and this is one reason for the increase in drug-resistant bacteria. We carried out this study to show antibiotics that are appropriate for each period of such infections. Bacteria obtained from postoperative infection sites in 114 patients with surgical site infections after gastrointestinal surgery were classified as first, second, third, and fourth isolates: the first isolates were taken when the administration of prophylactic antibiotics was finished, and the second, third, and fourth isolates were taken when the administrations of the first, second, and third therapeutic antibiotics, respectively, were finished. The incidence of drug-resistant strains was rare in strains isolated in the early phase of infections. The numbers of strains resistant to cephems and carbapenems increased as the clinical course of the infection progressed. New broad-spectrum antibiotics such as carbapenems should not be selected for the treatment of early-phase surgical site infections.

Effect of caffeic acid phenethyl ester on treatment of experimentally induced methicillin-res??stantStaphylococcus epidermidis endophthalmitis in a rabbit model

This study investigated the anti-inflammatory effects of caffeic acid phenethyl ester (CAPE), a natural bee-produced compound, and compared it with corticosteroids in the treatment of experimentally induced methicillin-resistant Staphylococcus epidermidis (MRSE) endophthalmitis in addition to intravitreal antibiotics. An experimental endophthalmitis model was produced in 24 New Zealand albino rabbits by unilateral intravitreal injection of 0.1 ml of 4.7 x 10(4) colony-forming units (CFU) methicillin-resistant S. epidermidis. The animals were then divided randomly into three treatment groups and a control group, group 1 (six rabbits), received only intravitreal vancomycin (1.0 mg/0.1 ml); group 2 (six rabbits), received both intravitreal vancomycin (1.0 mg/0.1 ml) and intravitreal dexamethasone (400 microg/0.1 ml) and group 3 (six rabbits), received both intravitreal vancomycin (1.0 mg/0.1 ml) and subtenon CAPE (10 mg/0.3 ml) after 24 h post-infection. No treatment was given to the control group. Treatment efficacy was assessed by clinical examination, vitreous culture and histopathology. There were no statististically significant differences between clinical scores of all groups in examinations at 24 and 48 h post-infection (p = 0.915 and p = 0.067 respectively), but in examinations at 72 h post-infection and after 7 days post-infection, although the clinical scores of treatment groups were not significantly different from each other, they were significantly lower than the control group (p < 0.05). The culture results of all groups were sterile. As a result, CAPE was found to be as effective as dexamethasone in reducing inflammation in the treatment of experimental MRSE endophthalmitis when used with antibiotics. More studies are needed to determine the optimal administration route and effective dosage of this compound.

The bactericidal effects of anti-MRSA agents with rifampicin and sulfamethoxazole-trimethoprim against intracellular phagocytized MRSA

We experienced therapeutic failure with vancomycin in patients with serious methicillin-resistant Staphylococcus aureus (MRSA) infections, in some of whom the bacteria were found to be alive in the leukocytes. We therefore evaluated the antimicrobial activity of several anti-MRSA agents (vancomycin, linezolid, quinupristin/dalfopristin, arbekacin) and co-administered agents (rifampicin, sulfamethoxazole-trimethoprim) against clinically isolated MRSA in phagocytized human polymorphonuclear leukocytes. After allowing the leukocytes to phagocytize the bacteria, the mixture was separated into leukocytes and supernatant, to which MRSA agents were added, and incubated for 24 h. After incubation, the leukocytes were crushed and the intracellular MRSA was cultured quantitatively. Vancomycin resulted in a less than 1% survival ratio of extracellular MRSA, but it was one of the highest ratios of intracellular MRSA with 33.8% compared with other agents. The survival ratios of intracellular MRSA with vancomycin plus rifampicin and with vancomycin plus rifampicin plus sulfamethoxazole-trimethoprim were 0.78% and 1.02%, respectively, which is significantly lower than that of vancomycin. For linezolid, quinupristin/dalfopristin, and arbekacin, there were no significant differences in the survival ratios between monotherapy and combination therapy against either extracellular or intracellular MRSA. The results suggest that the concomitant use of rifampicin or rifampicin plus sulfamethoxazole/trimethoprim with vancomycin is effective for MRSA phagocytized in leukocytes when vancomycin monotherapy is not sufficiently effective. Combination therapy showed no difference in efficacy in the case of linezolid, quinupristin/dalfopristin, and arbekacin.

Community-acquired methicillin-resistant Staphylococcus aureus: the role of Panton-Valentine leukocidin

Community-acquired (CA) methicillin-resistant Staphylococcus aureus (MRSA) infection among individuals without healthcare-associated (HA) risk factors was first recognized about a decade ago. It has now emerged as an epidemic that is responsible for rapidly progressive, fatal diseases including necrotizing pneumonia, severe sepsis and necrotizing fasciitis. Unlike HA-MRSA, CA-MRSA are usually pan-susceptible to non-beta-lactam antimicrobials. In addition to novel methicillin resistance genetic cassettes, many CA-MRSA harbor a phage harboring Panton-Valentine Leukocidin (PVL) genes and some data support the idea that PVL is responsible at least in part for the increased virulence of CA-MRSA. The tight association between the novel methicillin resistance cassettes and PVL phage cannot be explained, as they integrate into distinct sites on the S. aureus chromosome. This paper presents the evidence that CA-MRSA isolates are distinct strains emerging de novo from CA-methicillin susceptible isolates rather than from HA-MRSA isolates that have escaped from the hospital setting and that these novel CA-MRSA isolates may be more virulent than HA-MRSA. The second aim is to outline the progress in understanding the role of PVL in CA-MRSA pathogenesis.

Trends in the gentamicin and arbekacin susceptibility of methicillin-resistant Staphylococcus aureus and the genes encoding aminoglycoside-modifying enzymes

It is generally accepted that methicillin-resistant Staphylococcus aureus (MRSA) is also resistant to aminoglycoside antibiotics. We investigated trends of gentamicin and arbekacin susceptibilities and the prevalence of the genes encoding aminoglycoside-modifying enzymes (AMEs) for a total of 218 strains of MRSA isolated from blood specimens obtained from 1978 through 2002 in one hospital. The minimum inhibitory concentrations of gentamicin at which 50% of the strains were inhibited (MIC(50)) were > or =128 and 32 microg/ml for isolates obtained from 1978 to 1984 and from 1985 to 1989, respectively, and 0.5 microg/ml for isolates obtained from 1990 to 2002. The MIC(90) of gentamicin was consistently > or =128 microg/ml. Investigation of the occurrence of AME revealed that the MIC(50) of gentamicin was highly correlated with the presence of aac(6')/aph(2'') encoding aminoglycoside acetyl/phosphotransferase. The MIC(50) of arbekacin was 2 microg/ml for strains isolated in 1978-1984 and </=0.5 microg/ml for strains isolated from 1985 to 2002. The MIC(90) of arbekacin was 8 microg/ml for the strains isolated in 1978-1989 and 1 to 2 microg/ml for strains isolated in 1990-2002. Though it has been established that AAC(6')/APH(2'') modifies arbekacin, the trend of arbekacin resistance was not necessarily consistent with the presence of this enzyme. However, the prevalence of both aac(6')/aph(2'') and aph(3')-III in the strains isolated from 1978 through 2002 was correlated with the MIC(90) values of arbekacin. Thus, it is most likely that APH(3')-III, in addition to AAC(6')/APH(2''), is somehow involved in arbekacin resistance in S. aureus. Our results imply that gentamicin- and arbekacin-resistant MRSAs have consistently decreased for the past 25 years and that this finding is, most likely, attributable to the declining prevalence of genes encoding for AMEs.

Antibacterial Activity of Stilbene Oligomers against Vancomycin-Resistant Enterococci (VRE) and Methicillin-Resistant Staphylococcus aureus (MRSA) and Their Synergism with Antibiotics

Two resveratrol trimers, gnemonol B isolated from Gnetum gnemon and gnetin E obtained from the Gnetum species, were found to exhibit strong antibacterial activities against vancomycin-resistant Enterococci (VRE) and methicillin-resistant Staphylococcus aureus (MRSA). The MIC values of gnemonol B against five strains of VRE and nine strains of MRSA were 12.5 and 6.25 microg/ml, respectively. The MIC values of gnetin E against five strains of VRE and nine strains of MRSA ranged from 12.5 to 25microg/ml. These compounds also showed synergistic effects when used in combination with commercially available antibiotics according to the evaluation method using FIC indices. These findings suggested that the application of the test compounds alone or in combination with antibiotics might be useful in controlling and treating VRE and MRSA infections

MRSA in children presenting to hospitals in Birmingham, UK

Meticillin-resistant Staphylococcus aureus (MRSA) isolates from children presenting to Birmingham hospitals were characterized using molecular methods. The study was performed on MRSA isolates from children aged </=16 years, identified between March 2004 and December 2004, from three hospitals offering general paediatric services. Fifty isolates were classified as either community-acquired (CA-MRSA) or hospital-acquired MRSA (HA-MRSA) according to Centers for Disease Control and Prevention (CDC) criteria. They underwent susceptibility testing and pulsed-field gel electrophoresis (PFGE) analyses. Polymerase chain reaction (PCR) methodology was used to determine the type of staphylococcal chromosome cassette (SCCmec) and the presence or absence of genes encoding Panton-Valentine leucocidin (PVL). Overall, 31 (62%) MRSA were defined as CA-MRSA. PFGE band pattern and SCCmec analysis were similar to EMRSA 15 for 72% of isolates. Over 80% of isolates contained SCCmec type IV; one isolate was untypable. Genes encoding PVL were not detected. MRSA in children presenting to Birmingham hospitals classified as CA-MRSA are most likely to resemble the usual hospital epidemic strains. None of the isolates fulfilled the criteria for de-novo CA-MRSA based on PFGE, PVL production and SCCmec analysis.

Bisindole alkaloids of the topsentin and hamacanthin classes from a marine sponge Spongosorites sp

Seven new (1 and 3-8) and seven known (2 and 9-14) bisindole alkaloids of the topsentin and hamacanthin classes were isolated from the MeOH extract of a marine sponge Spongosorites sp. by bioactivity-guided fractionation. The structure of compound 7 is a revision from our previous report. The planar structures were established on the basis of NMR and MS spectroscopic analyses. Configurations of these compounds were defined by NMR spectroscopy and optical rotation. It is noteworthy that both R and S isomers were isolated for the hamacanthins (1-4, 9, 10, 15, and 16), while a single stereoisomer was isolated for dihydrohamacanthins (5, 11-14, 17, and 18). Compounds 1-4, 6, and 8-14 showed marginal cytotoxicity against five human solid tumor cell lines, and compound 2 showed weak antibacterial activity against clinically isolated methicillin-resistant strains.

The business of developing antibacterials

Although some dazzling technical approaches have fallen short, dozens of small companies and a few major pharmas seek new products for this medically crucial, modest-growth market.

Daryamides A-C, weakly cytotoxic polyketides from a marine-derived actinomycete of the genus Streptomyces strain CNQ-085

In the course of our continuing search for new antitumor-antibiotics from marine-derived actinomycete bacteria, four new cytotoxic compounds, designated as daryamides A (1), B (2), and C (3) and (2E,4E)-7-methylocta-2,4-dienoic acid amide (4), were isolated from the culture broth of a marine-derived Streptomyces strain CNQ-085. The structures of these new compounds were assigned by detailed interpretation of spectroscopic data. The relative configuration of 1 was determined by comprehensive NMR analysis, while the absolute configuration of 1 was determined as 4S,5R using the modified Mosher method. The daryamides show weak to moderate cytotoxic activity against the human colon carcinoma cell line HCT-116 and very weak antifungal activities against Candida albicans.

Rapid molecular detection of methicillin-resistant Staphylococcus aureus: a cost-effective tool for infection control in critical care?

Control strategies for methicillin-resistant Staphylococcus aureus (MRSA) in critical care remain debated. Timely detection of MRSA carriers is crucial to an effective isolation policy. In this issue, Harbarth and colleagues report rapid MRSA screening among intensive care unit-admitted patients using a PCR assay. Preemptive isolation for all admissions until screened negative for MRSA was associated with a reduction of intensive care unit-acquired MRSA infections in one of two study units. The data provide preliminary evidence to the effectiveness of a MRSA control strategy combining rapid screening by a molecular method and preventive isolation. Further controlled studies are needed to evaluate the cost-effectiveness of this intervention.

Restoration of oxacillin susceptibility in methicillin-resistant Staphylococcus aureus by blocking the MecR1-mediated signaling pathway

The signal transducing integral membrane protein, MecR1 helps initiate the expression of the antibiotic-resistant gene mecA, which encodes the penicillin-binding protein 2a. MecA participates in the beta-lactam resistance of methicillin-resistant Staphylococcus aureus (MRSA). Blocking the MecR1 regulatory pathway may be a novel strategy to combat MRSA. In this study, we introduced an antisense phosphothioate oligodeoxynucleotide (PS-ODN) targeting MecR1 mRNA into the MRSA strain WHO-2, which led to a significant reduction of both MecR1 and PBP2a mRNAs in a concentration-dependent manner. Consequently, the susceptibility of S. aureus WHO-2 to the beta-lactam antibiotic oxacillin was restored significantly. Our results indicate that blocking the mecR1-mecI-mecA signaling pathway via an antisense approach might be a viable strategy to restore the susceptibility of MRSA to the existing beta-lactam antibiotics.

Implementing an animated geographic information system to investigate factors associated with nosocomial infections: a novel approach

BACKGROUND

Two million Americans acquire an infection in the hospital each year, resulting in an estimated 88,000 patient deaths per year.

OBJECTIVE

Our objective was to describe our initial experience using an animated geographic information system (GIS) to investigate factors associated with nosocomial transmission of resistant organisms. We used a descriptive study at a university-affiliated, county, teaching hospital. We studied all patients and nursing staff on 4 adult, general medicine wards from June through August 2004.

RESULTS

We developed and implemented GIS software. GIS-generated animations demonstrated inappropriate patient placement for 19% of patients with methicillin-resistant Staphylococcus aureus and insufficient time for hand hygiene in 14% (6248) of health care provider-patient contacts.

CONCLUSION

Animated GIS can uncover previously hidden factors that contribute to the spread of nosocomial infections. This technology may become a useful adjunct for the prevention of nosocomial transmission of infectious agents.

Antimicrobial therapy of multidrug-resistant Streptococcus pneumoniae, vancomycin-resistant enterococci, and methicillin-resistant Staphylococcus aureus

Antibiotic resistance among pneumococci, enterococci, and staphylococci has become increasingly important in recent decades. Clinicians should be familiar with the nuances of antibiotic susceptibility testing and interpretation in selecting antibiotics for these infections. The clinical significance of penicillin-resistant Streptococcus pneumoniae, macrolide-resistant S pneumoniae, and multidrug-resistant S pneumoniae is discussed. The clinical spectrum and therapeutic approach to Enterococcus faecalis (i.e., vancomycin-sensitive enterococci) and E faecium (i.e., vancomycin-resistant enterococci) are discussed. Differences in therapeutic approach between methicillin-sensitive Staphylococcus aureus and methicillin-resistant S aureus (MRSA) infections are reviewed. Differences between in vitro susceptibility testing and in vivo effectiveness of antibiotics for hospital-acquired MRSA (HA-MRSA) are described. Finally, the clinical features of infection and therapy of HA-MRSA and community-acquired MRSA (CA-MRSA) infections are compared.

Changes in the epidemiology of meticillin-resistant Staphylococcus aureus associated with the emergence of EMRSA-16 at a university hospital

This study investigated the molecular epidemiology of meticillin-resistant Staphylococcus aureus (MRSA) in the University Hospital of the Canary Islands (HUC) in order to evaluate epidemiological changes over a six-year period. Clinical and epidemiological data were collected between May 2000 and December 2003, and isolates were subjected to pulsed-field gel electrophoresis (PFGE), multi-locus sequence typing (MLST), SCCmec typing and spa typing. Since 2000, the rate of MRSA infections has increased at the HUC, coinciding with the emergence and spread of the EMRSA-16 clone (ST36-MRSA-II) and replacement of the Iberian clone (ST247-MRSA-I). Genotypic changes were associated with changes in the epidemiological profile. The mean age and proportion of patients over 60 years old (P=0.01) and the proportion of respiratory infections (P=0.001) increased significantly. Gentamicin and tetracycline susceptibility of MRSA isolates increased (P<0.001) following the emergence of EMRSA-16. Combining PFGE, SCCmec and MLST has been instrumental in understanding these changes and defining the clones circulating in the HUC patient population.

Solid-phase synthesis and antibacterial activity of hydroxycinnamic acid amides and analogues against methicillin-resistant Staphylococcus aureus and vancomycin-resistant S. aureus

A library of hydroxycinnamic acid amides (HCAAs) and analogues were synthesized using solid-phase synthesis technique. These compounds were screened for antibacterial against methicillin-resistant Staphylococcus aureus (MRSA) (11 strains) and vancomycin-resistant S. aureus (VRSA) (4 strains). Dihydrocaffeoyl analogues showed activity against VRSA which were better than the reference drugs, vancomycin and oxacillin. These compounds also exhibited antibacterial activity against MRSA, which were more potent than oxacillin.

Efficacy of linezolid versus vancomycin in the treatment of methicillin-resistant Staphylococcus aureus discitis: a controlled animal model

STUDY DESIGN

A rabbit model was used to assess the efficacy of linezolid and vancomycin for the treatment of discitis due to methicillin-resistant Staphylococcus aureus (MRSA). Nontreated controls were used for comparison.

OBJECTIVE

The purpose of this study was to determine if there was a therapeutic difference between using linezolid and vancomycin in the treatment of MRSA discitis.

SUMMARY OF BACKGROUND DATA

Vancomycin is currently the gold standard treatment for medical management of MRSA discitis. Linezolid is a relatively new drug that has been approved for treatment of MRSA infections, but currently there is no research demonstrating its efficacy at treating infections of the disc space.

METHODS

Twenty-four rabbits were inoculated with MRSA at two adjacent lumbar disc spaces via an anterior retroperitoneal approach. Six rabbits were to receive only pain medication and to serve as controls. Ten rabbits were assigned to a 5-day course of intravenous vancomycin, and 8 were assigned to a 5-day course of intravenous linezolid. Disc spaces were sent for quantitative culture after the 5-day treatment course.

RESULTS

The mean culture growth for the disc spaces was not statistically different between the linezolid treated group and the nontreated controls. While vancomycin treatment did lead to lower bacterial loads when compared with controls, the reduction was not statistically significant. When bacterial counts for the vancomycin group and linezolid group were compared, vancomycin treatment resulted in less bacterial growth. This difference was statistically significant.

CONCLUSIONS

Linezolid is a clinically attractive alternative to vancomycin due to its mild side effect profile and oral bioavailability. However, in this MRSA discitis model with a short treatment course, vancomycin was superior to linezolid.

Effect of reduction in ciprofloxacin use on prevalence of meticillin-resistant Staphylococcus aureus rates within individual units of a tertiary care hospital

Previous studies have shown a correlation between fluoroquinolone use in hospitals and rates of meticillin-resistant Staphylococcus aureus (MRSA) infection. This study examined the effect on MRSA infection rates within individual adult units of a tertiary care teaching hospital after instituting a programme to decrease ciprofloxacin use. Clinical specimens positive for S. aureus were determined on all adult inpatient units between 1 January 2004 and 31 December 2005. Units with >10 isolates of S. aureus per year were included in the analysis. Ciprofloxacin use, measured in defined daily doses per 1000 patient-days, was determined for each unit during the same time period. Ciprofloxacin use and MRSA rates for 2004 and 2005 were compared. In the 17 units studied, ciprofloxacin use decreased by 31.2% (P<0.0001). The MRSA rate in these units decreased from 59.6% to 54.2% (P=0.122). There was a correlation between ciprofloxacin use and the MRSA rate within these units (r=0.70; 95% confidence interval -0.01-0.94; P=0.053). Within individual units, there was a variable response. In seven of the units, there was an increase in the MRSA rate despite a reduction in ciprofloxacin use, suggesting that other factors (length of stay, infection control and community-acquired MRSA) may have contributed. Although many factors are associated with high MRSA rates, ciprofloxacin use appears to be a contributing factor. Reducing the use of ciprofloxacin may be a means of controlling MRSA in the hospital setting.

Nasal carriage of pathogenic bacteria in medical students: effects of clinic exposure on prevalence and antibiotic susceptibility

Staphylococcus aureus is a major cause of community-acquired and nosocomial infections worldwide. One important source of this pathogen for nosocomial infections is the nasal carriage of S. aureus among hospital personnel. There are only a few studies investigating the carriage of S. aureus in a community of medical students. Oral and nasal flora of 179 medical students with varying clinical exposures were determined. Oral cultures revealed no nosocomial pathogen and nasal cultures showed an increasing rate of S. aureus carriage with increasing clinical exposure. Methicillin resistance also demonstrated a tendency toward increasing with increasing clinical exposure.

Antibiotic effects of WP-0405, a thermo-setting ofloxacin gel, on methicillin-resistant Staphylococcus aureus keratitis in rabbits

PURPOSE

The chemotherapeutic effects and pharmacokinetics properties of WP-0405 (a thermo-setting in situ 0.3% ofloxacin-containing ophthalmic gel) and ofloxacin (a conventional 0.3% ofloxacin solution) on methicillin-resistant Staphylococcus aureus (MRSA) keratitis were compared in a rabbit model.

METHOD

The single-instillation pharmacokinetics of WP-0405 and ofloxacin in the cornea, aqueous humor, conjunctiva, and iris-ciliary body were determined in normal rabbit eyes. To compare the duration of antimicrobial action, WP-0405 or ofloxacin was instilled oncedaily in an early-treatment model of keratitis, and corneas were either removed immediately or 4 or 8 h postinstillation. In another experiment, WP-0405 was instilled two or three times daily to compare its antibiotic efficacy with three-times daily instillation of ofloxacin in the same early-treatment model of keratitis; corneas were then removed after determining the extent of the abscess area. In another experiment, WP-0405 was instilled four or eight times daily to compare its effects with eight-times daily instillation of ofloxacin in a late-treatment model of keratitis, and corneas were removed. The number of viable bacteria in the corneas was determined in all experiments.

RESULTS

Cmax and AUC0- in tissues treated with WP-0405 were 1.5-3.4-fold and 1.8-2.9-fold greater than those treated with ofloxacin, respectively. WP-0405 significantly reduced the number of viable bacteria for up to 8 h after a single instillation. WP-0405 not only significantly reduced the number of viable bacteria, but also the size of the abscess area at the same frequency of instillation. When compared to ofloxacin, WP-0405 exhibited an approximately equivalent antibiotic effect, with fewer administrations.

CONCLUSIONS

As a result of its pharmacokinetics, WP-0405 had a more potent, longer-acting antibiotic effect than did ofloxacin. Furthermore, because of its lower required instillation frequency, which would improve patient compliance, WP-0405 has great potential therapeutic benefits.

A new monoterpene glycoside and antibacterial monoterpene glycosides fromPaeonia suffruticosa

Antibacterial activity-guided fractionation of the CHCI3-MeOH (1:1) extract of Paeonia suffruticosa root bark furnished three monoterpene glycosides, 6-O-vanillyoxypaeoniflorin (1), mudanpioside-H (2), and galloyl-oxypaeoniflorin (3). Of the isolated compounds, compound 1 is a new compound. All isolated compounds showed broad, but moderate, antibacterial activity with minimum inhibitory concentration (MIC) values in the range of 100 to 500 microg/mL against eighteen pathogenic microorganisms of concern for public health or zoonosis.