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Acinetobacter baumannii is a frequent cause of hospital-acquired pneumonia, and has recently increased in incidence as the causative agent of severe disease in troops wounded in Afghanistan and Iraq. Clinical approaches are limited since A. baumannii strains isolated from patients are extremely resistant to current antimicrobials. A. baumannii can survive desiccation and during outbreaks has been recovered from various sites in the patients' environment. To better understand its prevalence in hospital settings, we used a stainless steel washer (SSW) platform to investigate A. baumannii biofilm formation on abiotic surfaces. Scanning electron microscopy demonstrated that A. baumannii forms strong biofilms on stainless steel surfaces. This platform was combined with a colorimetric 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-5-[(phenylamino)carbonyl]-2H-tetrazolium hydroxide (XTT) reduction assay to observe the metabolic activity of bacterial cells, and to facilitate the manipulation and comparison of multiple A. baumannii clinical strains. A strong correlation between XTT and c.f.u. assays was demonstrated. To complement the cell viability assays, A. baumannii biofilm mass was measured by crystal violet staining. Furthermore, the effect of commonly used disinfectants and environmental stressors on A. baumannii biofilms and planktonic cells was compared and characterized. Biofilms on SSWs were significantly more resistant than their planktonic counterparts, providing additional evidence that may allow us to understand the high prevalence of this microbe in hospital settings. Our results validate that SSWs are a simple, versatile and innovative method to study A. baumannii biofilms in vitro.

Candida albicans is a leading fungal cause of burn infections in hospital settings, and sepsis is one of the principle causes of death after a severe burn. The prevalence of invasive candidiasis in burn cases varies widely, but it accounts for 3-23% of severe infection with a mortality rate ranging from 14 to 70%. Therefore, it is imperative that we develop innovative therapeutics to which this fungus is unlikely to evolve resistance, thus curtailing the associated morbidity and mortality and ultimately improving our capacity to treat these infections. An inexpensive and stable nitric oxide (NO)-releasing nanoparticle (NO-np) platform has been recently developed. NO is known to have direct antifungal activity, modulate host immune responses and significantly regulate wound healing. In this study, we hypothesized that NO-np would be an effective therapy in the treatment of C. albicans burn infections. Using a murine burn model, NO-np demonstrated antifungal activity against C. albicans in vivo, most likely by arresting its growth and morphogenesis as demonstrated in vitro. NO-np demonstrated effective antimicrobial activity against yeast and filamentous forms of the fungus. Moreover, we showed that NO-np significantly accelerated the rate of wound healing in cutaneous burn infections when compared to controls. The histological evaluation of the affected tissue revealed that NO-np treatment modified leukocyte infiltration, minimized the fungal burden, and reduced collagen degradation, thus providing potential mechanisms for the therapeutics' biological activity. Together, these data suggest that NO-np have the potential to serve as a novel topical antifungal which can be used for the treatment of cutaneous burn infections and wounds.

Purpose: To determine the antibacterial activity of fluoroquinolones, vancomycin, and gentamicin against methicillin-resistant Staphylococcus aureus (MRSA) ocular surface isolates., Design: Retrospective review., Methods: MRSA isolates were obtained from 21 patients. The MIC(50) (mean inhibitory concentration)(microg/ml) values of 31 MRSA ocular surface isolates were determined for gatifloxacin, moxifloxacin, ciprofloxacin, ofloxacin, vancomycin, and gentamicin using the Etest (AB Biodisk, Solna, Sweden) or the VITEK system (bioMérieux, Inc, Durham, North Carolina, USA). Susceptibility data were interpreted based on criteria specified by the Clinical and Laboratory Standards Institute (CLSI)., Main Outcome Measures: MIC(50) values in microg/ml and interpretation of susceptibility or resistance., Results: In vitro resistance rates and median MIC(50) in microg/ml for the MRSA isolates were: gatifloxacin (71%, 8.0), moxifloxacin (68%, 8.0), ciprofloxacin (94%, 8.0), ofloxacin (94%, 8.0), vancomycin (0%, 1.0), and gentamicin (3%, 0.5)., Conclusions: MRSA ocular isolates exhibited a relatively high rate of in vitro resistance to all fluoroquinolones tested, including the fourth generation. In contrast, MRSA isolates were found to be highly sensitive to vancomycin and gentamicin.

We investigated the in vitro susceptibilities of 23 Propionibacterium acnes ophthalmic isolates to ertapenem, meropenem, and cefepime by utilizing the Etest. The MICs ranged from 0.094 microg/ml to 0.75 microg/ml, 0.094 microg/ml to 1.5 microg/ml, and 1 microg/ml to 12 microg/ml for ertapenem, meropenem, and cefepime, respectively. Based on our excellent in vitro carbapenem susceptibility results, in vivo studies using ertapenem and meropenem in a rabbit model of P. acnes endophthalmitis are warranted.

This study evaluated personal digital assistant (PDA) microbial colonization before and after cleaning with alcohol. Samples from 75 PDAs were processed. Before cleaning, 96% of the samples were culture positive. After cleaning, 75% became culture negative. PDAs cleaned with an alcohol swab demonstrated significant reduction in colonization.

The relationship of initial concentration of Staphylococcus epidermidis in blood cultures and time to positivity (TTP) in an automated, continuously monitored blood culture system was assessed. Blood and 1 to 1,000 CFU of S. epidermidis per ml in stationary or exponential phase were inoculated in BACTEC Pediatric Plus F bottles and incubated. The TTP was inversely proportional to the initial inoculated concentration. Blood culture bottles with initial bacterial densities of <10 CFU/ml had a TTP of >20 h (upper limit of 95% prediction interval, 20.7 h) and bottles with initial bacterial densities of > or =50 CFU/ml had a TTP of < or =15 h (lower limit of 95% prediction interval, 13.4 h).

Propionibacterium acnes has been identified as a significant agent of nosocomial infections, including endophthalmitis. Data concerning susceptibility of P. acnes to newer beta-lactam antibiotics and fluoroquinolones are limited. Recent reports suggest that quinolones have activity against these organisms sufficient to warrant further study. We undertook a study to select appropriate antimicrobial agents for use in a rabbit model of P. acnes endophthalmitis. We compared the antibiotic susceptibilities of P. acnes by using the National Committee for Clinical Laboratory Standards method of agar dilution with the E test. Thirteen clinical isolates obtained from eye specimens and three American Type Culture Collection control strains were tested against 14 antibiotics. All the clinical isolates were susceptible by both methods to piperacillin, piperacillin-tazobactam, ampicillin-sulbactam, ticarcillin-clavulanate, cefotaxime, cefotetan, ceftriaxone, cefoxitin, and imipenem in addition to clindamycin but were resistant to metronidazole. The clinical P. acnes isolates also displayed high-level susceptibility to ciprofloxacin, sparfloxacin, and ofloxacin. Almost all the P. acnes strains demonstrated E-test MICs within 2 dilutions of the MICs observed by the agar dilution method. Those few strains for which discrepancies were noted exhibited E-test susceptibilities three- to fivefold dilutions lower than the agar dilution method susceptibilities but only with ampicillin-sulbactam, ticarcillin-clavulanate, and/or clindamycin. On the basis of our study, all of clinical eye isolates were susceptible to these newer antimicrobial agents and the two methods demonstrated similar susceptibility patterns.

After the growth of Paecilomyces persicinus P-10 in a glucose-peptone medium, filtrates were collected and analyzed for antibiotic antivity. Activities against Salmonella gallinarum ATCC 3030 and Alcaligenes faecalis ATCC 8750 (penicillin N-resistant strain) were obtained. Part of the former activity was readily inactivated by penicillinase. The fraction active against A. faecalis was isolated by passage through Amberlite XAD-2 and Amberlite IRA-68. The powder eventually obtained was subjected to paper chromatography followed by bioautography, and the activity obtained corresponded to that of a sample of cephalosporin C. Thin-layer chromatography was also employed to verify the presence of cephalosporin C in the P-10 powder. The active solids were further purified by means of paper chromatography in a solvent system consisting of n-butanol-acetic acid-water (60:15:25, vol/vol). The material obtained from this procedure yielded an infrared absorption spectrum identical to that of cephalosporin C. Similarly, the ultraviolet absorption of the purified preparation coincided with that of cephalosporin C. Exposure of the purified solids to cephalosporinase resulted in rapid inactivation of the antibiotic. In addition to penicillin N and cephalosporin C, filtrates of P. persicinus P-10 also contained deacetylcephalosporin C, deacetoxycephalosporin C, and cephalosporin P.

Escherichia coli recovered from a nosocomially acquired urinary tract infection required 48 h of incubation on blood agar and did not grow on other routine clinical laboratory media. This bacterium dissociated readily into three colony types, all of which were confirmed as E. coli by DNA hybridization studies. Preliminary studies indicate a prolonged lag phase that could not be corrected by the addition of a variety of peptones and yeast extracts. Better growth was achieved by the addition of 10% horse serum.

Leuconostoc species are gaining importance as pathogenic organisms. We present the first case of odontogenic infection caused by Leuconostoc spp. Isolates initially identified as streptococci were found to be vancomycin resistant. Rigorous bacteriologic investigation subsequently classified these organisms as Leuconostoc mesenteroides.

Vancomycin-resistant Streptococcus salivarius-like bacteria were isolated from the blood and gastrostomy tube of a 6-month-old child during vancomycin therapy for Staphylococcus epidermidis central venous catheter-associated bacteremia. The isolates produced D-(-)-lactate and ethanol from glucose, hydrolyzed esculin, and produced no ammonia from arginine, thus fulfilling the major criteria as Leuconostoc spp. The enzymatic profile of the bacteria suggested that they were not lactobacilli or streptococci. Resistance to vancomycin and penicillin tolerance were noted. The formula fed through the gastrostomy tube was suspected as the vehicle that transmitted the organism to the patient. Penicillin and tobramycin therapy was used successfully.

Indwelling central-line catheters (n = 502) from 362 patients in intensive care units were analyzed prospectively. The skin site, 6-cm-distal and -proximal subcutaneous segments of the catheter, exudates, and blood were cultured. Semiqualitative roll plate cultures of the catheter segments were followed by broth cultures and examined for 72 h. All isolates were identified, and susceptibilities were determined. Line infections, defined clinically, yielded 22 different microbial species; 10 different species were recovered from colonized lines. Of the Staphylococcus epidermidis isolates recovered, 39% occurred singly and 21% occurred in combination with other microorganisms; Enterococcus faecalis, S. hominis, and Pseudomonas aeruginosa were next in frequency of isolation. Line infections also yielded other staphylococci, viridans group streptococci, several members of the family Enterobacteriaceae, acinetobacters, anaerobic bacteria, Candida spp., and Aspergillus fumigatus. While S. epidermidis was also the most frequent isolate among the line colonizers, different species and different frequencies of isolation were found among this group. The study showed that the distal catheter segment broth culture was the best predictor of clinical line infections; in addition, gram-negative bacteria were isolated only from the catheters of patients with overt infections.