Responsible Pathogen Research Articles

Linezolid Treatment for Gram-Positive Infections: A Retrospective Comparison with Teicoplanin

In randomized studies linezolid, indicated for Gram-positive infections, was as effective as teicoplanin in critical ill patients or was superior to teicoplanin in skin infection, pneumonia and bacteremia. We performed a 2-year comparative, retrospective study of patients treated with linezolid or teicoplanin in a single hospital for the same indications. We collected information about the type of infection, the responsible pathogen, therapy administered before study drugs, antibiotic associated with the study drugs, length of hospital stay (LOS), adverse events and outcome of the infections. The aim of the study was to evaluate the efficacy of linezolid in this retrospective patients series.Overall we identified 169 patients treated with linezolid and 91 with teicoplanin. Response to therapy, (resolution or improvement of infection) was better in patients treated with linezolid compared to teicoplanin (83.9% versus 69.2%, p=0.002). Response to therapy by type of pathogen showed the superior efficacy of linezolid against Staphylococcus aureus (including MRSA) and enterococci; although not statistically significant because of the small number of patients enrolled, they were close to significance (p<0.056 for S. aureus, p<0.055 for MRSA, p<0.061 for enterococci). Overall LOS in linezolid-treated patients was 4.6 days (p<0.041) less. Empirical use of linezolid reduced LOS by 6 days (p<0.038), especially in VAP and bacteremia patients (p<0.05). Mortality due to infection was 9.8% in both groups, and adverse events were most frequently documented in linezolid-treated patients. Linezolid was clinically superior to teicoplanin in the treatment of Gram-positive infections.

Ventilator-associated pneumonia: an overview

Despite aggressive efforts to reduce nosocomial infections, many intubated patients develop ventilator-associated pneumonia (VAP). VAP has been an area of intense research; however, there is still little consensus in the literature on how to accurately diagnose or treat VAP. VAP complicates the course of 8 – 28% of mechanically ventilated patients and mortality varies greatly from 8 to 76%, depending on the specific population being studied. Once pneumonia is suspected, bacteriologic confirmation should be obtained and empiric therapy must be instituted as soon as possible, as a delay in therapy or inappropriate therapy greatly increases mortality. Initial antibiotic therapy should be based on the most common organisms in each hospital or unit, and the most likely pathogens for that specific patient. Constant surveillance of the responsible pathogens through the use of antibiograms allows clinicians to make educated choices for antibiotics. When final cultures and sensitivities are available, de-escalation to less broad spectrum antibiotics should be performed. If cultures show no bacterial growth, antibiotics should be discontinued so that patients are not exposed to unnecessary antibiotics. Following these practices will help to decrease multi-resistant strains of bacteria and can improve the morbidity and mortality of VAP.

Chronic Bone Infections Due to Enterobacter cloacae: Current Therapeutic Trends and Clinical Outcome

Chronic osteomyelitis is a difficult-to-treat infection which often necessitates surgical debridement and prolonged administration of antibiotics 1. enterobacter cloacae are a very rare cause of osteomyelitis and of septic arthritis with adjacent osteomyelitis and spondylodiskitis. Published experience is limited to sporadic cases 2-4 and little is known about the clinical course and outcome of the disease. A case-series of 15 adult patients with chronic bone infections by e. cloacae is presented. A retrospective analysis of 15 cases of bone infections caused by e. cloacae was made. Data for analysis derived from an electronic registry of 768 patients with chronic bone and joint infections followed-up in the Outpatients Department of infectious Diseases of the 4th Department of internal Medicine during the period 1998-2008. Written informed consent for use of each patient’s data for publication was provided upon admission. Described cases met the following inclusion criteria: i) documentation of chronic bone infection by clinical and radiological criteria; and ii) implication of e. cloacae as the responsible pathogen. More precisely, e. cloacae was isolated either from cultures of infected bone and/or surrounding tissues sampled intra-operatively or from cultures of an orthopedic implant device or from pus aspirated proximally to the infected tissue by radiological guidance. Patients not eligible for analysis were: i) those with isolation of e. cloacae from a sinus tract; and ii) those with isolated e. cloacae considered as a superinfection of a previous staphylococcal infection. Diagnosis of bone infection was performed by the following criteria 5: i) presence of local signs of inflammation and/or sinus tract formation at the infection site; ii) erythrocyte sedimentation rate (EsR) more than 30 mm/h and C-reactive protein (CRP) more than 15 mg/L (normal values below 5 mg/L); and iii) radiological proof of infection by positive findings on x-ray and magnetic resonance imaging. identification of e. cloacae was performed by testing of its biochemical properties (APi20E, bioMerieux, Mercy L’Etoile, France). Antimicrobial susceptibility testing was done by the Kirby-Bauer disk diffusion assay with interpretation criteria according to the Clinical and Laboratory standards institute 6. The production of extended-spectrum b-lactamase (EsBL) was defined by the double disk approximation test and of AmpC b-lactamases by the application of a cefoxitin disk. The type of antimicrobial therapy was based on the susceptibility testing of the pathogen. All patients were followed-up on a monthly basis. Duration of therapy was decided by the attending physician. For each patient the following data were recorded: age, gender, co-existing diseases, type, dose and duration of therapy and performance of surgical debridement. Clinical arrest of the infection was considered as any resolution of clinical and radiological findings accompanied by restoration of EsR and CRP within normal ranges. All other cases were considered treatment failures. Patients with arrest of the infection and those who failed treatment were compared regarding the performance of surgical debridement by the Fischer’s exact test; and for the duration of treatment by the Mann-Whitney U test. Any value of p <0.05 was considered significant. Clinical characteristics of described cases are shown in table 1. in six cases, osteomyelitis followed an orthopedic operation; none of these patients was admitted to an intensive Care Unit (iCU) after operation. All isolates were EsBL and AmpC b-lactamase producers. susceptibility testing of the offending pathogens was as follows: carbapenems 100%, trimethoprim/sulfamethoxazole 60%, ciprofloxacin 86%. Based on the susceptibility of the pathogens, the most commonly prescribed regimens were ciprofloxacin in 12 cases and carbapenems in 3 cases. surgical debridement was performed in 9 cases. Arrest of the infection was achieved in 9 cases. These patients did not relapse within the first year after cessation of therapy. surgical debridement was performed in 6 out of 9 patients with arrest of the infection; and in 4 out of 6 patients with treatment failure (pns). Median duration of therapy for patients with arrest of the 4th Department of internal Medicine, University of Athens, Medical school, Greece

Incidence of Hajj-associated febrile cough episodes among French pilgrims: a prospective cohort study on the influence of statin use and risk factors

A prospective epidemiological study was conducted to evaluate the incidence of febrile cough episodes among adult Muslims travelling from Marseille to Saudi Arabia during the Hajj pilgrimage and to assess if use of statin had an influence on this incidence. In total, 580 individuals were presented with a questionnaire. A significant proportion of individuals had chronic medical disorders, e.g. diabetes mellitus (132, 22.8%) and hypertension (147, 25.3%). Pilgrims had a low level of education and a low employment rate. Sixty (10.3%) were treated with statins for hypercholesterolemia. Four hundred and fourty-seven pilgrims were presented a questionnaire on returning home. A total of 74 travellers (16.6%) experienced fever during their stay in Saudi Arabia (67 attended a doctor) and 271 (60.6%) had cough (259 attended a doctor); 70 travellers with cough were febrile (25.9%). Seventy per cent of the travellers who suffered cough episodes developed their first symptoms within 3 days, suggesting a human to human transmission of the responsible pathogen, with short incubation time as evidenced by a bimodal distribution of cough in two peaks at a 24 h interval. None of demographical and socioeconomic characteristics, underlying diseases or vaccination against influenza significantly affected the occurrence of cough. Diabetes correlated with an increased risk of febrile cough (OR = 2.02 (1.05–3.89)) as well as unemployment (OR = 2.22 (0.91–5.53)). Use of statins had no significant influence on the occurrence of cough and/or fever during the pilgrimage. This result suggests that while treatment with a statin has been demonstrated to reduce the mortality from severe sepsis associated with respiratory tract infections, it probably does not play a role in the outcome of regular febrile cough episodes as observed in the cohort studied here.

Failure of linezolid therapy for post-neurosurgical meningitis due to Enterococcus faecium

Nosocomially acquired intracranial infections may be caused by a wide array of microorganisms, including staphylococci, enterococci, Gram-negative bacilli and yeasts. In the presence of prosthetic devices, the treatment of choice for infections caused by Gram-positive organisms is removal of the device and iv administration of vancomycin. However, experimental and clinical data suggest that the penetration of vancomycin into CSF is poor and sometimes unpredictable in cases without severe meningeal inflammation. Some authors have reported that in patients with meningitis, continuous intravenous administration of vancomycin may lead to higher penetration, though in patients without meningitis CSF concentrations usually remain below 4 mg/L. 2 The breakpoint concentration for susceptible organisms may not be achieved consistently in patients without severe meningeal inflammation, even when high daily doses of up to 4 g are used. Therefore, some authors advocate intrathecal administration of vancomycin, although a comprehensive evaluation of the benefits has yet to be made and the associated risks, such as ototoxicity, remain unclear. 2 Treatment of ampicillin-resistant enterococcal infections is further complicated by the fact that the activity of vancomycin is bacteriostatic. The CSF may not be sterilized unless bactericidal activity is established by the addition of gentamicin. 1 These factors, and the desire to avoid further surgery to establish intrathecal access, made linezolid an attractive treatment option for our patient. Linezolid is the first licensed member of the oxazolidinone class of antibiotics with activity against almost all Gram-positive pathogens. Excellent tissue penetration and 100% oral bioavailability are notable properties of linezolid and it is approved in Europe and the USA for the treatment of nosocomial pneumonia, skin and soft tissue infections and, in the USA, vancomycin-resistant E. faecium and methicillin-resistant Staphylococcus aureus (MRSA) infections. 3 Linezolid has also been shown to have good penetration into the CNS. 4 A 2007 review of the evidence regarding the use of linezolid for the treatment of patients with CNS infections identified 42 relevant cases. In the 39 patients in whom the responsible pathogen was isolated, those predominantly responsible for the CNS infections were: penicillin-non- susceptible Streptococcus pneumoniae (7; 17.9%), vancomycin-resistant enterococci (6; 15.4%), Nocardia spp. (5; 12.8%), methicillin-resistant Staphylococcus epidermidis (4; 10.3%) and MRSA (3; 7.7%). Of the 42 patients treated with linezolid, 38 were either cured or showed clinical improvement. 5 Case reports of other authors have found that enterococci disappeared from the CSF after as little as 2 days of iv linezolid treatment. 6

Kingella kingae: osteoarticular infections of the sternum in children: a report of six cases

Kingella kingae is increasingly recognized as a pathogen of osteoarticular infections (OAI) below the age of 2 years. It was reported that bones and joints which are rarely infected by other pathogens were frequently invaded by K. kingae. Based on a series of six cases, we present the typical clinical and paraclinical manifestation of K. kingae infections of the sternum and sterno-manubrial joint. A review of the clinical, laboratory, radiological, microbiological, and molecular data of six consecutive children admitted to a paediatric unit for OAI of the sternum was done. Culture alone allowed for the detection of K. kingae as the responsible pathogen in three cases, molecular methods in the three other cases. Clinical and laboratory findings, as well as imaging methods, proved to be useful in the diagnostic process. Our findings suggest that infections of the lower sternum and the junction between the manubrium and the xyphoid process are typical, if not pathognomonic, for the organism. A respective diagnostic and therapeutic protocol was established.

Metagenomic analysis indicates that stressors induce production of herpes-like viruses in the coral Porites compressa

During the last several decades corals have been in decline and at least one-third of all coral species are now threatened with extinction. Coral disease has been a major contributor to this threat, but little is known about the responsible pathogens. To date most research has focused on bacterial and fungal diseases; however, viruses may also be important for coral health. Using a combination of empirical viral metagenomics and real-time PCR, we show that Porites compressa corals contain a suite of eukaryotic viruses, many related to the Herpesviridae. This coral-associated viral consortium was found to shift in response to abiotic stressors. In particular, when exposed to reduced pH, elevated nutrients, and thermal stress, the abundance of herpes-like viral sequences rapidly increased in 2 separate experiments. Herpes-like viral sequences were rarely detected in apparently healthy corals, but were abundant in a majority of stressed samples. In addition, surveys of the Nematostella and Hydra genomic projects demonstrate that even distantly related Cnidarians contain numerous herpes-like viral genes, likely as a result of latent or endogenous viral infection. These data support the hypotheses that corals experience viral infections, which are exacerbated by stress, and that herpes-like viruses are common in Cnidarians.

Surgical site infections: epidemiology, microbiology and prevention

Surgical site infections (SSIs) are defined as infections occurring up to 30 days after surgery (or up to one year after surgery in patients receiving implants) and affecting either the incision or deep tissue at the operation site. Despite improvements in prevention, SSIs remain a significant clinical problem as they are associated with substantial mortality and morbidity and impose severe demands on healthcare resources. The incidence of SSIs may be as high as 20%, depending on the surgical procedure, the surveillance criteria used, and the quality of data collection. In many SSIs, the responsible pathogens originate from the patient's endogenous flora. The causative pathogens depend on the type of surgery; the most commonly isolated organisms are Staphylococcus aureus, coagulase-negative staphylococci, Enterococcus spp. and Escherichia coli. Numerous patient-related and procedure-related factors influence the risk of SSI, and hence prevention requires a 'bundle' approach, with systematic attention to multiple risk factors, in order to reduce the risk of bacterial contamination and improve the patient's defences. The Centers for Disease Control and Prevention guidelines for the prevention of SSIs emphasise the importance of good patient preparation, aseptic practice, and attention to surgical technique; antimicrobial prophylaxis is also indicated in specific circumstances. Emerging technologies, such as microbial sealants, offer the ability to seal and immobilise skin flora for the duration of a surgical procedure; a strong case therefore exists for evaluating such technologies and implementing them into routine clinical practice as appropriate.

Adverse effects of parenteral antimicrobial therapy for chronic bone infections

Responsible pathogens of chronic bone infections (CBI) are frequently resistant, requiring parenteral antimicrobial therapy. Therefore, adverse effects may be observed. We have determined the rate of adverse effects of antimicrobial therapy for CBI in a retrospective study of all patients receiving parenteral drugs via an implantable port. Patients from one medical ward (n = 89) and from one surgical ward (n = 40) between January 1995 and December 2005 were included in this study. The CBI included were 85 osteomyelitis (66%) and 44 prosthetic joint infections (34%). The main group of pathogens was gram positive cocci (n = 144; 65%). The total duration of antibiotic treatment was 205 +/- 200 days, including 133 +/- 100 days for parenteral therapy. Thirty-three catheter-related complications were observed in 27 patients (21%). All complications led to hospitalization but none led to death. Twenty-one antibiotic-related complications occurred in 18 patients (16%), and one allergic reaction led to death. The mean duration of follow-up was 290 days. Remission was observed in 84 patients (65%). In multivariate analysis, adverse effects were mostly observed in the medical department. Adverse effects affect at least one third of the patients treated for CBI with parenteral antimicrobial therapy and are related to both the implantable port and the antibiotic compounds.

A Universal Combination Treatment for Vaginitis

Vaginitis, most often due to bacterial vaginosis or Candida species, remains the most common reason for visiting a gynecologist. The diagnosis may be difficult because the clinical findings are not specific for different causative agents and because some of the responsible pathogens are part of the vaginal flora. This randomized, double-blind, controlled, multicenter trial compared Clo-Met, a vaginal tablet containing 100 mg each of clotrimazole and metronidazole, with clotrimazole alone in 165 women presenting with vaginal discharge who were diagnosed as having vaginitis caused by Trichomonas vaginalis, bacterial vaginosis, Candida albicans, or any combination of these agents. Participants had not been treated for vaginitis during the past month. Eighty-four women taking part in this study were assigned to combined treatment and 81 to clotrimazole alone. The 2 groups were similar in age, educational level, and marital status. Women in both groups reported having had an average of about 5 past episodes of vaginitis. The only diagnosis made frequently enough to analyze was C. albicans vaginitis and, in these women, treatment with Clo-Met proved to be more effective than clotrimazole alone. The therapeutic cure rate, comprising both clinical and microbiologic cures, was 89.5% with Clo-Met and 64.7%, a statistically significant difference. Logistic regression analysis yielded an odds ratio for a beneficial response to Clo-Met 4.6 times greater than with clotrimazole alone. Among women with candidal growth at baseline, 83% of those given Clo-Met and 65.5% of those treated with clotrimazole alone had negative cultures 30 days after starting treatment. The patients, in general, regarded both treatments as being effective. One patient taking clotrimazole had a strong vaginal burning sensation that led her to discontinue medication. The Clo-Met vaginal table appears to be an effective and safe treatment for vaginitis. In this trial, Clo-Met was significantly more effective than clotrimazole alone in eliminating C albicans infection.

A prospective comparison of nursing home-acquired pneumonia with hospital-acquired pneumonia in non-intubated elderly

There are no prospective comparison of the etiology and clinical outcome between hospital-acquired pneumonia (HAP) and nursing home-acquired pneumonia (NHAP) in non-intubated elderly. This study prospectively evaluated the etiology of HAP and NHAP in non-intubated elderly. A prospective cohort study was carried out in a rural region of Japan where the population over 65 years of age represents 30% of the population. A total of 108 patients were enrolled. There were 33 patients with HAP and 75 with NHAP. Etiologic diagnosis was established in 78.8% of HAP and in 72% of NHAP patients. The most frequent pathogens were Chlamydophila pneumoniae followed by Streptococcus pneumoniae, Staphylococcus aureus and Influenza virus. The frequency of Streptococcus pneumoniae and Influenza virus was significantly higher, whereas the frequency of Staphylococcus aureus and Enterobacteriaceae was significantly lower in NHAP compared to HAP. Performance and nutritional status were significantly worse in patients with HAP than in those with NHAP. Hospital mortality was significantly lower in patients with NHAP compared to those with HAP. This study demonstrated that C. pneumoniae, Streptococcus pneumoniae, Staphylococcus aureus and Influenza virus are frequent causative agents of pneumonia in non-intubated elderly and that the responsible pathogens and clinical outcome differ between NHAP and HAP.

A Trial of Aerosolized Colistin for the Treatment of Nosocomial Pneumonia due to Multidrug-resistant Acinetobacter baumannii

Background: Recently, multidrug-resistant (MDR) A. baumannii has been implicated for a significant proportion of nosocominal pneumonia in many intensive care units (ICUs), and its acquisition may increase mortality and the length of stay in the ICU. Aerosolized colistin has been successfully used in patients with cystic fibrosis, but there is a lack of data regarding the use of aerosolized colistin in patients with nosocomial pneumonia. Methods: We conducted the present study to assess the effectiveness of aerosolized colistin for the treatment of MDR A. baumannii nosocomial pneumonia. We retrospectively reviewed the medical records of 10 patients who had been hospitalized in the medical ICU and had received aerosolized colistin as a therapy for MDR A. baumannii pneumonia. Results: The mean duration of aerosolized colistin therapy was days. Nine (90%) of 10 patients showed a favorable response to the therapy. Follow-up cultures were available for all patients, and the responsible pathogen was completely eradicated. One patient suffered from bronchospasm, which resolved after treatment with nebulized salbutamol. Conclusion: Our results corroborate previous reports that aerosolized colistin may be an effective and safe choice for the treatment of nosocomial pneumonia caused by MDR A. baumannii. Larger prospective controlled clinical studies are warranted to validate further the effectiveness and safety of aerosolized colistin therapy.

Contemporary management of infected total knee replacement

Purpose of review: Deep infection following knee arthroplasty is unquestionably a major complication, with potentially devastating consequences. There is a risk of considerable morbidity, the cost of treatment can be high, and the loss of some function is possible even if the infection is successfully controlled. The large number of recent publications devoted to this problem is a testament to its clinical significance. Recent findings: The two-stage approach utilizing antibiotic impregnated polymethyl methacrylate spacers has significant advantages when considering exchange arthroplasty. Articulating antibiotic polymethyl methacrylate spacers have become a popular method for staged management of infected total knee replacement. Not only do these spacers significantly improve patient mobility and comfort between stages, but their use also potentially facilitates subsequent reimplantation. Summary: Successful management involves selection of treatment alternatives based on specific criteria. The responsible pathogen, the patients' immunologic status, the chronicity of infection, and the stability of the implant must all be carefully considered. When all of these criteria are favorable, retention of the prosthetic components may be considered, but when any of these criteria are unfavorable retention of the components is more likely to result in treatment failure. For deep infection of more than 3 weeks' duration most expert surgeons recommend a staged approach to management.

Preemptive treatment of fungal infection: has its time arrived in liver transplantation?

Background Invasive fungal infection remains a major challenge in liver transplantation and the mortality rate is high. Early diagnosis and treatment are required for better results. Patients We prospectively measured plasma (1 → 3)β-d glucan (BDG) levels in 180 living donor liver transplant recipients for 1 year after surgery. Fungal infection was defined as proposed by the European Organization for Research and Treatment of Cancer/Mycoses Study Group. Preemptive treatment (intravenous fluconazole and trimethoprim-sulfamethoxazole) was started when the BDG level was greater than 40 pg/ml. Results Twenty-four patients (13%) were diagnosed with invasive fungal infection. The responsible pathogens included Candida spp. in 14 cases, Aspergillus fumigatus in 5, Cryptococcus neoformans in 3, and Pneumocystis jiroveci in 2. Preemptive treatment was performed in 22% of patients (n = 40). Renal impairment and mild gastrointestinal intolerance due to the drugs were observed in 28% (11/40) of patients during treatment. Among them 14 patients were diagnosed with fungal infection including seven candidiasis, five aspergillosis, and two Pneumocystis jiroveci pneumonia. The sensitivity and specificity of BDG for overall fungal infection was 58% and 83%, respectively, with a positive predictive value of 35% and a negative predictive value of 93%, and a positive likelihood ratio of 3.41 and a negative likelihood ratio of 1.98. The overall mortality for fungal infection in our series was 0.6%. Conclusion Although the sensitivity and positive predictive value were low, the low mortality rate after fungal infection and the mild side effects of the preemptive treatment might justify our therapeutic strategy. Based on the effectiveness, this strategy warrants further investigation.

Preemptive Treatment of Fungal Infection Based on Plasma (1 → 3)β-D-Glucan Levels after Liver Transplantation

Invasive fungal infection remains a major challenge in liver transplantation and the mortality rate is high. Early diagnosis and treatment are required for better results. We prospectively measured plasma (1 --> 3)beta-D-glucan (BDG) levels in 180 living donor liver transplant recipients for 1 year after surgery. Fungal infection was defined as proposed by the European Organization for Research and Treatment of Cancer/Mycoses Study Group. Preemptive treatment (intravenous fluconazole and trimethoprim-sulfamethoxazole) was started when the BDG level was greater than 40 pg/ml. Twenty-four patients (13%) were diagnosed with invasive fungal infection. The responsible pathogens included Candida spp. in 14 cases, Aspergillus fumigatus in 5, Cryptococcus neoformans in 3, and Pneumocystis jiroveci in 2. Preemptive treatment was performed in 22% of patients (n = 40). Renal impairment and mild gastrointestinal intolerance due to the drugs were observed in 28% (11/40) of patients during treatment. Among them 14 patients were diagnosed with fungal infection including seven candidiasis, five aspergillosis, and two Pneumocystis jiroveci pneumonia. The sensitivity and specificity of BDG for overall fungal infection was 58% and 83%, respectively, with a positive predictive value of 35% and a negative predictive value of 93%, and a positive likelihood ratio of 3.41 and a negative likelihood ratio of 1.98. The overall mortality for fungal infection in our series was 0.6%. Although the sensitivity and positive predictive value were low, the low mortality rate after fungal infection and the mild side effects of the preemptive treatment might justify our therapeutic strategy. Based on the effectiveness, this strategy warrants further investigation.

Psoas abscess in patients with an infected aortic aneurysm

Psoas abscess is an uncommon disease, and its presenting features are usually nonspecific. Infected aortic aneurysms could be complicated by psoas abscess. A retrospective chart review was conducted to examine the incidence, clinical presentations, microbiology, and outcomes of psoas abscess in patients with an infected aortic aneurysm. Between 1996 and 2007, 40 patients (32 men) with an infected infrarenal aortic aneurysm were treated in our hospital. Their median age was 71 years (range, 38 to 88 years). In 38 patients a blood or tissue culture had a positive result. The most common responsible pathogen was Salmonella spp in 29 patients (76%), followed by Staphylococcus aureus in 3 (8%), Escherichia coli in 2 (5%), Klebsiella pneumoniae in 3 (8%), and Mycobacterium tuberculosis in 1 (3%). One patient underwent endovascular repair but died. In-situ graft replacement was done in 32 patients. Persistent or recurrent infection occurred in seven (22%) of 32 operated on patients. The mortality rate was 86%, and the overall aneurysm-related mortality rate of in situ graft replacement was 22% (7/32). In eight (20%) of the 40 patients, aortic infection was complicated by psoas abscess. Infection complicated by psoas abscess was present in seven of 32 operated patients. It was associated with higher incidence of emergency operation, hospital mortality, prosthetic graft infection, and aneurysm-related mortality than infection without abscess. Psoas abscess was common in patients with infected infrarenal aortic aneurysm. Salmonella spp was the most common pathogen. Psoas abscess was associated with a high mortality rate, emergency operation, and persistent infection.

Surgical Pathology of Infected Aortic Aneurysm and Its Clinical Correlation

Pathology of infected aortic aneurysm and its clinical correlation have rarely been reported. Between 1995 and 2005, 48 patients with infected aortic aneurysm underwent in situ graft replacement. Twenty-five patients had a suprarenal and 23 patients had an infrarenal infection. The most common responsible pathogen was nontyphoid Salmonella in 32 patients (67%). During operation, gross pus was present in 26 patients (54%). On pathological examination, aortic atherosclerosis was present in all cases, acute suppurative inflammation was present in 31 patients (65%), and bacterial clumps were present in five patients (10%). Positive culture of the aneurysm wall was present in 14 patients (29%). There were 10 patients with prosthetic graft infection (21%) and 12 patients with aneurysm-related death (25%). Although statistically insignificant, local purulent infection with positive culture of the aneurysm wall, gross pus during operation, or acute suppurative inflammation on pathology tended to be associated with high risk of prosthetic graft infection and aneurysm-related death. In conclusion, infected aortic aneurysm occurred in patients with aortic atherosclerosis. On pathology, acute suppurative inflammation was present in the majority of cases but bacterial clumps were not commonly present. Local purulent infection tended to be associated with high risk of prosthetic graft infection and aneurysm-related death.

Empiric therapy for secondary peritonitis: A pharmacodynamic analysis of cefepime, ceftazidime, ceftriaxone, imipenem, levofloxacin, piperacillin/tazobactam, and tigecycline using Monte Carlo simulation

Background:Inappropriate antibiotic therapy (ie, the selection of an empiric agent without activity against the responsible pathogen) of secondary peritonitis may result in poor patient outcomes. The selection of an appropriate agent can be challenging because of the emerging resistance of target organisms to commonly prescribed antibiotics. Objective:The aim of this study was to perform a pharmacodynamic analysis, using recent global surveillance data, of commonly prescribed antibiotic agents and a newer agent, tigecycline, indicated in 2005 for the treatment of complicated intra-abdominal infections, to determine their probability for achieving microbiologic success against aerobic bacteria associated with secondary peritonitis. Methods:A 2-compartment model was constructed using pharmacokinetic data from critically ill patients and global surveillance data on MIC distributions for microorganisms encountered in secondary peritonitis. A Monte Carlo simulation of the modeled data was performed to determine drug-appropriate pharmacodynamic end points, including free-drug time above the MIC, steady-state concentration above the MIC, and AUC/MIC ratios. A cumulative fraction of response (CFR) against aerobic bacteria involved in secondary peritonitis was calculated for cefepime, ceftazidime, ceftriaxone, imipenem, levofloxacin, pip eracillin/tazobactam, and tigecycline. A CFR ≥90% was considered microbiologic success. The following treatment regimens, administered as 30-minute N infusions, were examined: cefepime 1 and 2 g q12h, ceftazidime 1 and 2 g q8h, ceftriaxone 1 and 2 g q24h, imipenem 500 mg q6h, levofloxacin 750 mg q24h, pip eracillin/tazobactam 3.375 g q6h, and tigecycline 50 mg q12h, after a loading dose of 100 mg. Results:A CFR ≥90% against nonenterococcal bacteria was predicted for imipenem 500 mg q6h (96.8%), cefepime 2 and 1 g q12h (95.3% and 92.4%, respectively), ceftazidime 2 g q8h (94.2%), and piperacillin/tazobactam 3.375 g q6h (91.2%). A CFR of 84.5% was predicted for tigecycline 50 mg q12h. Ceftriaxone and levofloxacin were predicted to have a CFR <80%. When enterococci were included in the model, the predicted CFRs for imipenem, piperacillin/tazobactam, and tigecycline were 93.4%, 88.4%, and 86.7%, respectively. Conclusions:MIC distribution and pathogen prevalence strongly influence the likelihood of microbiological success in secondary peritonitis; therefore, decisions regarding empiric therapy should consider local epidemiology. Using current global data, the following regimens are adequate choices if Enterococcus is not targeted: Combination therapy (with metronidazole) using cefepime 1 g or 2 g q12h, or ceftazidime 2 g q8h; or monotherapy with imipenem 500 mg q6h or piperacillin-tazobactam 3.375 g q6h. When Enterococcus is included in the epidemiologic mix, imipenem, piperacillin/tazobactam, and tigecycline all appear to be viable monotherapeutic choices.

Nosocomial infection in small for gestational age newborns with birth weight

Objective:To investigate whether preterm newborns who are small for gestational age are at increased risk of nosocomial infections and necrotising enterocolitis.Design, setting and subjects:The German national surveillance system for nosocomial...

Pathology of fatal traumatic and nontraumatic clostridial gas gangrene: a histopathological, immunohistochemical, and ultrastructural study of six autopsy cases

We prospectively investigated six fatal cases of clostridial gas gangrene using autopsy, histology, immunohistochemistry, microbiology, and scanning electron microscopy. The causative pathogen was Clostridium perfringens in four cases, C. sordellii in one case, and a mixed infection with both C. perfringens and C. sordellii in one case. According to the previous medical history and autopsy findings, clostridial infection was related to trauma in three cases. Characterized by extensive tissue necrosis and total absence of an accompanying leukocyte infiltration and tissue inflammatory response, the histopathological picture of clostridial gas gangrene is distinctly different from other bacterial infections. In medicolegal casework, the proof of the source of infection and the portal of entry of the responsible pathogen is not always an easy task, especially in the absence of trauma.