On-site Gram staining that increases a post-test probability of an ominous infection: a case of necrotizing fasciitis caused by Vibrio vulnificus: a case report.

BACKGROUND: Gram staining is a classic but standard and essential procedure for the prompt selection of appropriate antibiotics in an emergency setting. Even in the era of sophisticated medicine with technically developed machinery, it is not uncommon that a classic procedure such as Gram staining is the most efficient for assisting physicians in making therapeutic decisions in a timely fashion. CASE PRESENTATION: A 65-year-old Asian man with alcoholic cirrhosis complicated by esophageal varices was brought to the emergency division of Saga Medical School Hospital in early August, complaining of severe pain, redness, swelling, and purpura of the lower extremities. On physical examination he appeared in a critically ill condition suggestive of deep-seated soft tissue infection, raising a pre-test probability of streptococci, staphylococci, Vibrio sp., or Aeromonas sp. as a causative pathogen. A characteristic of his residency in an estuarine area is that raw seafood ingestion, as documented in this patient prior to the current admission, predisposes those who have a chronic liver disease to a life-threatening Vibrio vulnificus infection. Given the pathognomonic clinical features suggestive of necrotizing fasciitis, our immediate attempt was to narrow down the differential list of candidate pathogens by obtaining clinical specimens for microbiological investigation, thus inquiring about the post-test probability of the causative pathogen. The Gram stain of the small amount of discharge from the test incision of the affected lesion detected Gram-negative rods morphologically compatible with V. vulnificus. After two sets of blood culture, intravenous meropenem and minocycline were immediately administered before the patient underwent emergency surgical debridement. The next day, both blood culture and wound culture retrieved Gram-negative rods, which were subsequently identified as V. vulnificus by mass spectrometry, matrix-assisted laser desorption/ionization. The antibiotics were switched to intravenous ceftriaxone and minocycline. CONCLUSION: The pre-test probability of V. vulnificus infection was further validated by on-site Gram staining in the emergency division. This case report highlights the significance of a classic procedure.

Is trimethoprim/sulfamethoxazole-associated increase in serum creatinine a pseudo-elevation or true nephrotoxicity?

INTRODUCTION: The aim of this study was to determine the rates of trimethoprim/sulfamethoxazole (TMP/SMX)-associated pseudo-elevation and true nephrotoxicity by comparison of creatinine-estimated and cystatin C-estimated GFRs (glomerular filtration rates) before and after TMP/SMX administrations. METHODS: Patients in whom serum creatinine and cystatin C were simultaneously measured are the cohort of this study. A decreasing of creatinine-estimated GFR posterior to TMP/SMX by ≥ 20% and a decreasing of cystatine C-estimated GFR posterior to TMP/SMX by ≥ 20% were defined as true nephrotoxicity. A decreasing of creatinine-estimated GFR posterior to TMP/SMX by ≥ 20% and a decreasing of cystatine C-estimated GFR posterior to TMP/SMX by < 20% were defined as pseudo-elevation. RESULTS: A total of 66 patients were enrolled. Within the 19 patients in whom serum creatinine and cystatin C were measured simultaneously both before and after TMP/SMX administrations, 10 patients (52.6%) had nephrotoxicity. Fewer random error and systematic bias between creatinine- and cystatine C-estimated GFR were observed after TMP/SMX than before TMP/SMX by Bland-Altman analysis. CONCLUSIONS: Using cystatin C, we reveled TMP/SMX-associated nephrotoxicity is not uncommon. We should equally pay attention to TMP/SMX-associated nephrotoxicity and pseudo-elevation. In spite of pseudo-elevation, creatinine-estimated GFR after receiving TMP/SMX is ironically reliable as surrogate maker for renal clearance.

Clinical pharmacokinetic and pharmacodynamic analysis of daptomycin and the necessity of high-dose regimen in Japanese adult patients.

The objective of this study was to explore the optimal dosage regimen of daptomycin and to determine the necessity and validity of a high-dose regimen from the perspectives of PK/PD parameters using Monte Carlo Simulation (MCS) and therapeutic drug monitoring (TDM) in a Japanese clinical setting. The volume of distribution (0.13 ± 0.012 L/kg) in this study was greater than that in healthy volunteers reported in Japan. The range of half-lives was between 8.9 and 34.9 h, which were gradually prolonged as creatinine clearance decreased. In MCS, the cumulative fractions of response (CFR) of the peak/MIC â‰§ 60 and the AUC/MIC â‰§ 666 at the 6 mg/kg q 24 h were 72.0% and 78.8% but at the 10 mg/kg q 24 h, the CFRs improved to both 99%. In TDM with 6 mg/kg q 24 h regimen, the patients who reached the peak and AUC target were 40% (2 out of 5 patients), respectively. The intraindividual variability in daptomycin PK may indicate the necessity of TDM and high-dose regimen, such as over 8 mg/kg, may be needed to ensure the effectiveness especially on Japanese patients with normal renal function.

Clinical utility of direct application of matrix-assisted laser desorption ionization time-of-flight mass spectrometry and rapid disk diffusion test in presumptive antimicrobial therapy for bacteremia.

OBJECTIVE: To study how and to what degree the rapid pathogen identification by MALDI-TOF MS coupled with rapid disk diffusion test improve the current clinical practice of patients with bacteremia in a tertiary teaching hospital with full-time ID consultation service. PATIENTS AND METHODS: MALDI-TOF MS and 8H disk diffusion tests were directly applied to the positive blood cultures samples and the results were reflected on antimicrobial therapy (n = 119). The appropriateness of antimicrobial selection through these interventions was verified with conventional culture results in comparison with historical control (n = 129). The mortality of patients between the two periods was also compared. RESULTS: The appropriateness of antimicrobial selection was higher (99.2%) in the intervention than in the control group (93.8%) (p 0.024), but there was no difference in 28-day mortality between the two periods (16.8%, 14.8%) (p 0.668). The duration of presumptive antimicrobial therapy with anti-MRSA agents and carbapenem antibiotics did not differ between the two periods indicating that the intervention was not effective in decreasing the unnecessary antibiotics. On the other hand, some bacteremic patients with pathogens whose drug susceptibilities were invariably sensitive to the standard class of antibiotics definitely benefitted from the intervention. CONCLUSION: The intervention utilizing MALDI-TOF MS and the rapid disk diffusion test may not demonstrate overall improvement in bacteremia mortality in the institution with full-time infectious disease consultants. Its utility has yet to be evaluated in different setting hospitals.

Staphylococcus saprophyticus native valve endocarditis in a diabetic patient with neurogenic bladder: A case report.

A 61-year-old man was admitted to our hospital with 2-day history of malaise and dyspnea. He had mitral prolapse and type II diabetes mellitus with neurogenic bladder, which was cared for by catheterization on his own. On arrival the patient was in septic condition with hypoxemia, and physical examination revealed systolic murmur at the apex. Transthoracic echocardiography revealed vegetation of the mitral and the aortic valve. The presence of continuous bacteremia was confirmed by multiple sets of blood culture, whereby gram-positive cocci was retrieved and identified as Staphylococcus saprophyticus (S. saprophyticus) both phenotypically and genetically. Because two major criteria of the Modified Duke Criteria were met, the patient was diagnosed with native valve endocarditis due to S. saprophyticus. The urine culture was also positive for gram-positive cocci, phenotypically identified as Staphylococcus warneri, which was subsequently identified as S. saprophyticus with the use of 16S rRNA gene sequence analysis and MALDI-TOF MS (matrix-assisted laser desorption ionization time of flight mass spectrometry), indicating strongly that the intermittent catheterization-associated urinary tract infection resulted in bacteremia that eventually lead to infective endocarditis. This patient was treated with vancomycin and clindamycin. Because of multiple cerebral infarctions, the patient underwent mitral and aortic valve replacement on hospital day 5. Blood culture turned negative at 6th hospital day. Antibiotic therapy was continued for six weeks after surgery. The patient's clinical course was uneventful thereafter, and was discharged home. This is the first case report of native valve endocarditis caused by S. saprophyticus of confirmed urinary origin.

Clinical features of enterococcal bacteremia due to ampicillin-susceptible and ampicillin-resistant enterococci: An eight-year retrospective comparison study.

Enterococcus consists human bowel flora, but sometimes behave as an important nosocomial pathogen. In order to identify clinical characteristics that help discriminate between ampicillin-susceptible and ampicillin-resistant enterococcal bacteremia in advance for antimicrobial susceptibility testing, a retrospective eight-year study was carried out in patients with enterococcal bacteremia experienced in Saga University Hospital, Japan. A total of 143 patients were included in the analysis: 85 (59.4%) with bacteremia caused by ampicillin-susceptible enterococci and 58 (40.6%) by ampicillin-resistant strains. Hospital-acquired bacteremia was present in 79.0% (113/143) of patients. Abdominal infections, urinary tract infections, and unknown source were predominant foci for the two groups. Patients with ampicillin-resistant enterococcal bacteremia was significantly associated with hematological cancer, immunosuppressive therapy, prior use of antibiotics, and mucositis associated with febrile neutropenia. The 28-day mortality was significantly higher in ampicillin-resistant enterococcal bacteremia. On multivariate analysis, independent risk factors for ampicillin-resistant enterococci were as follows: prior exposures to penicillins and carbapenems, and bacteremia related to mucositis with febrile neutropenia. These findings would assist physicians in deciding whether glycopeptide antibiotics should be included as an empiric antibiotic therapy in patients with suspected enterococcal infections and also those with persistent neutropenic fever refractory to fourth generation cephalosporin. A few cases of MALDI-TOF MS-identified Enterococcus faecium that turned out ampicillin-sensitive were also described to emphasize the importance of taking epidemiological aspects of patients into considerations when deciding initial antimicrobial treatment.

The importance of pharmacokinetic consultation of cefepime treatment for Pseudomonas aeruginosa bacteremia: a case report of severe thermal burn injury.

The patient is a 54-year-old man with severe thermal burn injury involving 45.5% of the total body-surface area, complicated with bacteremia caused by Pseudomonas aeruginosa with a cefepime MIC of 8 µg/ml. The plasma concentrations of cefepime 1 g every 6 h measured by validated high performance liquid chromatography were 25.8 µg/ml at 1 h and 6.28 µg/ml at 5 h after infusion, and 3.9 µg/ml before the infusion, when creatinine clearance was increased to 136 ml/min by vigorous fluid replacement. The pharmacokinetic-pharmacodynamic analyses in the one-compartment model with use of the Sawchuk-Zaske method revealed marked increase in the volume of distribution (28.9 l), total clearance (10.7 l/h), and shortening of plasma half- life (1.79 h) of cefepime, with time >MIC and 24-h area under the concentration-time-curve being 58% and 358, respectively. These pharmacokinetic parameters of cefepime quantified in the patient estimated a time >MIC of 87% if administered every 4 h. P. aeruginosa, however, was successfully eradicated without revision of the dosing regimen of cefepime. Decrease in creatinine clearance by correction of the fluid imbalance and wound closure by skin graft surgery likely contributed to the restoration of fluid shift, resulting in normal disposition of cefepime and favorable clinical outcome of the patient.