Pyogenic Brain Abscess Research Articles

Paradoxical Presentation In A Case of Deep Frontal Lobe Abscess

A pyogenic brain abscess may start initially with cerebritis and later develop a capsule and a necrotic centre thus, forming an abscess. A pyogenic abscess is not uncommon and can be due to a multitude of organisms. It may occur due to spread from a contiguous focus, haematogenous spread or head trauma etc. We report here, a case with no detectable source of infection in a case with a left to right shunt patent foramen ovale (PFO). Such a shunt is an unusual presentation as only a right to left shunt is known to bypass the pulmonary filter and lead to seeding, in the absence of a coexisting pulmonary arteriovenous malformation.

Pyogenic Brain Abscess Management and Outcome

Suppurative intracranial infections are devastating conditions that previously carried high mortality and long-term disability. Unfortunately, there is

Pyogenic brain abscess in children: a Tunisian multi-center experience.

Brain abscess (BA) is an uncommon intracranial suppurative infectious disease, especially in children. Treatment involves surgery and prolonged courses of antibiotics. Our study aimed to describe clinical characteristics of children with BA treated in middle Tunisian health centers. A retrospective study lasting 19 years (1995-2014) was conducted in Tunisia middle region. Forty one children having radiologic abnormalities suggestive of BA and confirmed per operative lesions were included. Mycobacterial, parasitic or fungal abscesses were excluded. Medical records were analyzed for age, gender, presenting symptoms, predisposing factors, imaging, microbiology results, treatment and outcome. The mean age was 4.9 years. The most common clinical presentations were intracranial hypertension symptoms (87%). BA was diagnosed in 95.1% on the basis of cranial imaging. The majority of abscesses was supra-tentorial (92.6%). The most frequent etiology was loco-regional infections (63.4%). No predisposing factor was found in 17%. Intravenous antibiotics were given in all cases with surgical drainage in 63.4%,. Causative organisms were identified in 53.7%. The mortality rate was 24.3%. Age less than 2 years was the only statistically significant prognostic factor identified. Our study confirmed the severity of this pathology and underlined the importance of early diagnosis and management.

Predictors of unprovoked seizures in surgically treated pyogenic brain abscess: Does perioperative adjunctive use of steroids has any protective effect?

ObjectiveThough outcome of brain abscess has been improved due to stereotactic drainage and appropriate antibiotic treatment, late unprovoked seizure often occurs after the abscess is resolved. The purpose of this study is to reveal the factors related to the late unprovoked seizure and effect of steroid on the prevention of seizure. Patients and MethodsFrom January 2002 to August 2016, 119 patients with supratentorial brain abscesses were retrospectively analyzed. Initial volume of abscess, surgical methods, use of antiepileptic drugs (AEDs), and seizure free survival according to the use of steroid were compared between seizure free and late unprovoked seizure patients groups. Factors related to the late unprovoked seizure were evaluated by multivariate logistic regression model. ResultsAll patients underwent surgery, which were either by burrhole aspiration or craniotomy. 22/119 patients (18.5%) had late unprovoked seizure. Initial abscess volume was significantly larger in the group of late unprovoked seizure (28.31 ± 22.68 cm3 vs. 17.03 ± 14.53 cm3, p = 0.015). The mean time to the late unprovoked seizure was 487.7 ± 446 days (range, 11–1369 days). Steroid was used to relieve perilesional edema in 35 patients. Proportion of late onset seizure was not different between the group of steroid non-use group and steroid use (17.1% vs. 19%, p = 0.52) and mean seizure free periods of steroid non-use group and steroid use group were 40.75 ± 9.23 months and 48.85 ± 8.50 months, respectively (P = 0.89, by log rank test). Initial presentation of seizure at the diagnosis of brain abscess and initial volume larger than 20.89 cm3 were risk factors for late unprovoked seizure with odds ratio of 4.1 (95% C.I 1.44–11.69) and 3.08 (95% C.I 1.19–7.96), respectively. ConclusionLate unprovoked seizure in patients with brain abscess was affected by initial presentation of seizure and initial volume of the abscess whereas methods of surgical intervention and steroid use had no effect on the occurrence of late unprovoked seizure.

Pyogenic brain abscess and subdural empyema: presentation, management, and factors predicting outcome.

To describe the presentation and management of bacterial brain abscess and subdural empyema in adults treated at two tertiary centers. In addition, to identify factors that may predict a poor clinical outcome. A retrospective analysis of data obtained from clinical records was performed, followed by multivariate regression analysis of patient and treatment-related factors. 113 patients were included with a median age of 53years and a male preponderance. At presentation symptoms were variable, 28% had a focal neurological deficit, and 39% had a reduced Glasgow coma scale (GCS). Brain abscesses most frequently affected the frontal, temporal, and parietal lobes while 36% had a subdural empyema. An underlying cause was identified in 76%; a contiguous ear or sinus infection (43%), recent surgery or trauma (18%) and haematogenous spread (15%). A microbiological diagnosis was confirmed in 86%, with streptococci, staphylococci, and anaerobes most frequently isolated. Treatment involved complex, prolonged antibiotic therapy (> 6 weeks in 84%) combined with neurosurgical drainage (91%) and source control surgery (34%). Mortality was 5% with 31% suffering long-term disability and 64% achieving a good clinical outcome. A reduced GCS, focal neurological deficit, and seizures at presentation were independently associated with an unfavorable clinical outcome (death or disability). Complex surgical and antimicrobial treatment achieves a good outcome in the majority of patients with bacterial brain abscess and subdural empyema. Factors present at diagnosis can help to predict those likely to suffer adverse outcomes. Research to determine optimal surgical and antibiotic management would be valuable.

Pyogenic Brain Abscess in Children: A Tunisian Multi-Centric Experience

Background: Brain Abscess (BA) is an uncommon intracranial suppurative infectious disease, especially in children. Its treatment involves surgery and prolonged antibiotics courses. Objectives: The current study aimed at describing the clinical characteristics of children with BA, treated at the central Tunisian region health center. Methods: A retrospective study, lasting 19 years (1995 to 2014), was conducted in four Tunisia pediatric departments of the central region. Forty-one children having radiological abnormalities suggestive of BA and confirmed operative lesions were included. Mycobacterial, parasitic or fungal abscesses were excluded. Medical records were analyzed for age, gender, presenting symptoms, predisposing factors, imaging, microbiology findings, treatment, and outcome. Results: The mean age was 4.9 years (range: 4 days to 16 years). The most common clinical presentations were increased intracranial pressure symptoms (87%). Brain Abscess was diagnosed in 95.1% on the basis of cranial imaging. The majority of abscesses were supratentorial (92.6%). The most frequent etiology was contiguous infections of the skull (63.4%). No predisposing factor was found in 17%. Intravenous antibiotics were given in all cases with surgical drainage in 63.4%, causative organisms were identified in 53.7%; gram positive cocci in 21.9%, and gram negative cocci in 9.7%. The mortality rate was 24.3%. Age of less than two years was the only statistically significant identified prognostic factor. Conclusions: The current study confirmed the severity of this pathology and underlined the importance of early diagnosis and management.

Pyogenic brain abscess caused by Serratia marcescens in a Brazilian premature neonate

Bacterial brain abscess remain a serious central nervous system infectious disorder despite advances in neurosurgical, neuroimaging, clinical support on intensive care units, microbiological techniques and availability of new antibiotics. The successful treatment of brain abscess usually requires surgery, appropriate antibiotic therapy and eradication of the primary source. Although uncommon, brain abscesses are particularly important in the pediatric population due to its devastating potential to cause severe neurologic deficits, especially in preterm newborns. The purpose of the present report is to describe the case of a Brazilian premature neonate with pyogenic brain abscesses caused by Serratia marcescens and to discuss therapeutic and diagnostic approaches. The early suspicion, proper diagnostic measures and immediate neurosurgical consultation associated with aggressive antibiotic therapy seem to be the essentials steps on themanagement for those high-risk pediatric patients.

Rare case of pyogenic brain abscess in a immunocompetent children caused by Streptococcus intermedius

Rare case of pyogenic brain abscess in a immunocompetent children caused by Streptococcus intermedius

A 9 Year Old Female Ethiopian Patient with Stage IV Retroviral Infection and Right Side Hemiparesis

A 9-year-old, 17 kg, female patient was admitted to pediatric ward of a large, teaching referral hospital in Addis Ababa, Ethiopia because of high grade fever (HGF), severe headache & abnormal body movement (ABM) of 1 month duration. The child was taking unspecified Highly Active Antiretroviral Therapy (HAART) regimen from another government hospital ART clinic and unspecified per os (PO) medicines and herbs ordered from private clinics and traditional herbalists, respectively. She was put on Tenofovir/Lamivudine/Efavirenz (TDF/3TC/EFV) fixed dose combination therapy since 8 months back and has been taking phenytoin 50mg PO BID for the last one and half year. The patient has no known drug allergy (NKDA) or allergic diseases. Brain Computed Tomography (CT) scan was done on 27/02/2017 and revealed the presence of Pyogenic Brain Abscess (PBA) with subfalcine Herniation. Abdominal ultrasound was done on 08/03/2017 and showed Hepatomegaly. Head Magnetic Resonant Imaging (MRI) was done on 09/03/2017 and showed Left Frontoparietal Multiloculated Ring Enhancing Lesion with calcification and extensive vasogenic edema & mass effect more likely a Tuberculosis Brain Abscess (TBA). Chest X-ray (CXR) was done on 09/03/2017 with anterioposterior & left lateral position and revealed Left Upper Lobe Opacity more likely Tuberculosis (TB). Patient’s hemoglobin (Hgb), mean corpuscular volume (MCV) and mean corpuscular hemoglobin (MCH) all were below normal on two consecutive measurements indicating that patient was suffering from moderate microcytic anemia. The Erythrocyte sedimentation rate (ESR) was also elevated as indication of non specific chronic inflammatory conditions most probably due to TB. Urinalysis was done on date 06/03/2017 and showed slight elevation in Red Blood Cells (RBCs) and White Blood Cells (WBCs) count and serum electrolyte assessment showed potassium was slightly below normal and chloride was increased and serum pH was slightly high causing metabolic alkalosis. Furthermore, alkaline phosphatase (ALP) was slightly elevated indicating involvement of cranial bone and focal hepatic lesions. Based on the clinical, laboratory and imaging evidences, the final working diagnosis was Stage IV RVI on HAART plus Right Sided Hemiparesis Secondary to TBA and PBA plus Focal Seizure. The gradual worsening of ABM of right lower and upper extremities could be due to lack of appropriate titration of the dose of phenytoin. The Initial dose of phenytoin has to be initiated with 5 mg/kg/day orally in 2 or 3 equally divided doses, with subsequent dosage individualized to a maximum of 300 mg PO daily. The maintenance dose should be 4 to 8 mg/kg and for children over 6 years old and adolescents may require the minimum adult dose (300 mg/day). The major drug therapy problems identified in this case was the prescription of rifampin with dexamethasone or prednisolone. Rifampin has been known to decrease the level or effect of dexamethasone-prednisolone by affecting hepatic/intestinal CYP3A4 enzyme metabolism. Hence, avoiding the use or use of alternative drug was recommended. Based on subjective evidences from the patient, now the patient is feeling better. Imaging modalities and laboratory tests are expected to be repeated and further progress report will be reported in future correspondence as short communication or to the editorial note

Simultaneous detection of valine and lactate using MEGA-PRESS editing in pyogenic brain abscess.

Valine and lactate have been recognized as important metabolic markers to diagnose brain abscess by means of MRS. However, in vivo unambiguous detection and quantification is hampered by macromolecular contamination. In this work, MEGA-PRESS difference editing of valine and lactate is proposed. The method is validated in vitro and applied for quantitative in vivo experiments in one healthy subject and two brain abscess patients. It is demonstrated that with this technique the overlapping lipid signal can be reduced by more than an order of magnitude and thus the robustness of valine and lactate detection in vivo can be enhanced. Quantification of the two abscess MEGA-PRESS spectra yielded valine/lactate concentration ratios of 0.10 and 0.27. These ratios agreed with the concentration ratios determined from concomitantly acquired short-TE PRESS data and were in line with literature values. The quantification accuracy of lactate (as measured with Cramér-Rao lower bounds in LCModel processing) was better for MEGA-PRESS than for short-TE PRESS in all acquired in vivo datasets. The Cramér-Rao lower bounds of valine were only better for MEGA-PRESS in one of the two abscess cases, while in the other case coediting of isoleucine confounded the quantification in the MEGA-PRESS analysis. MEGA-PRESS and short-TE PRESS should be combined for unambiguous quantification of amino acids in abscess measurements. Simultaneous valine/lactate MEGA-PRESS editing might benefit the distinction of brain abscesses from tumors, and further categorization of bacteria with reasonable sensitivity and specificity.

Abcès cérébraux à pyogènes de l’adulte

Pyogenic brain abscesses (BA) are rare and their diagnosis may be difficult because of the absence of specific clinical or biological signs. However, the use of diffusion-weighted brain MRI sequences has modified the management of BA, as they are highly sensitive and specific to differentiate pyogenic brain abscesses from necrotic tumors, which are the most frequent differential diagnosis in case of ring-enhancing lesions on CT scan. This new tool allows for a rapid diagnosis and should be followed by a CT-guided aspiration of BA. This safe procedure should be performed if possible before starting antibiotics in order to optimize microbiological diagnosis. Recent epidemiological changes include an increase in the numbers of immunocompromised patients and a decrease in the traditional causes of BA (direct inoculation, ear nose and throat infections, etc.). In consequence, a wider range of bacterial species may be involved, making it all the more necessary to obtain a microbiological diagnosis. Many uncertainties remain in terms of the duration of antibiotic treatment, the optimal radiological follow-up and the place for associated treatments such as corticosteroids and anticonvulsive therapy. BA remain severe infections with high mortality and morbidity rates; the factor most regularly associated with a poor prognosis is the patients neurological status at diagnosis.

Atypical pyogenic brain abscess evaluation by diffusion-weighted imaging: diagnosis with multimodality MR imaging.

Whether a brain abscess is apparent by imaging depends on the stage of the abscess at the time of imaging, as well as the etiology of the infection. Because conventional magnetic resonance imaging (MRI) is limited in its ability to distinguish brain abscesses from necrotic tumors, advanced techniques are required. The management of these two disease entities differs and can potentially affect the clinical outcome. We report a case having atypical imaging features of a pyogenic brain abscess on advanced MRI, in particular, on diffusion-weighted and perfusion imaging, in a patient with osteosarcoma undergoing chemotherapy.

Surgery for Pyogenic Brain Abscess over 30 Years: Evaluation of the Roles of Aspiration and Craniotomy.

To evaluate the roles of craniotomy and aspiration in the treatment of pyogenic brain abscess throughout 30 years of computerized tomography. A retrospective study of 224 patients who were surgically treated at Istanbul Medical Faculty, Department of Neurosurgery between 1982 and 2012 was undertaken. The records were analyzed for demographic, clinical and radiological findings, surgical interventions (resection, free-hand aspiration and image-guided aspiration), data regarding abscesses (etiological factors, site, size, number, localization and identified microorganism), corticosteroid and antibiotic usage and complications, and the outcomes were reviewed. The male-to-female ratio was 2.2, and the mean age was 26.2±1.25 years. The most common presenting symptom was headache (56.7%), followed by nausea and vomiting (28.5%). Otitis media and mastoiditis were the most common causes of abscess (41.9%), and 44 patients had multiple abscesses. Aerobic gram-positive microorganisms were the most frequently isolated pathogens in culture (51.5%). Primary surgical interventions were as follows: craniotomy and resection (38.8%), free-hand aspiration (49.1%) and image-guided aspiration (12.1%). The aspiration-to-resection ratio was 1.36 (64/47) in the first decade, 2.94 (50/17) in the second decade and 1 (23/23) in the last decade. Age, level of consciousness at the time of admission and potent corticosteroid usage were found to be significantly associated with mortality (p=0.001, p≤0.001 and p=0,038, respectively). The total morbidity and mortality ratios were 4.9% and 9.8%, respectively. Seizures were more common in patients of craniotomy group (p=0.023). Treatment of pyogenic brain abscess remains challenging, despite advances in surgical and imaging technology, and craniotomy retains a significant role in surgical treatment.

Subdural Empyema Complicating Bacterial Meningitis: A Challenging Diagnosis in a Patient with Polysubstance Abuse.

Subdural empyema (SDE) and cerebrovascular accident (CVA) are uncommon life-threatening complications of bacterial meningitis, which require urgent neurosurgical intervention to prevent adverse outcomes. Clinicians must be vigilant of the onset of focal neurologic deficits or seizure activity to establish the diagnosis of SDE. Streptococcus pneumoniae accounts for <1% of pyogenic brain abscesses. This case describes a presentation of community acquired pneumococcal pneumonia in which the diagnosis of SDE with vasculitis induced CVA was confounded by concomitant substance abuse and sedation.

Discriminating pyogenic brain abscesses, necrotic glioblastomas, and necrotic metastatic brain tumors by means of susceptibility-weighted imaging.

To investigate the feasibility of using susceptibility-weighted imaging (SWI) to discriminate abscesses and necrotic tumours. Twenty-one patients with pyogenic abscesses, 21 patients with rim-enhancing glioblastomas and 23 patients with rim-enhancing metastases underwent SWI. Intralesional susceptibility signal (ILSS) was analyzed employing both qualitative (QL) and semi-quantitative (SQ) methods. Logistic regression models and receiver operating characteristic analysis were used to demonstrate the discriminating power. In QL analysis, ILSSs were seen in 12 of 21 abscesses, in 20 of 21 glioblastomas, and in 16 of 23 metastases. In SQ analysis, a low degree of ILSS (85.8 %) was in the majority of abscesses and a high degree of ILSS (76.2 %) was in the majority of glioblastomas. SQ model was significantly better than QL model in distinguishing abscesses from glioblastomas (P < .001). A derived ILSS cutoff grade of 1 or less was quantified as having a sensitivity of 85.7 %, specificity of 90.5 %, accuracy of 88.1 %, PPV of 90.0 %, and NPV of 86.4 % in distinguishing abscesses from glioblastomas. A high-grade ILSS may help distinguish glioblastomas from abscesses and necrotic metastatic brain tumours. The lack of ILSS or low-grade ILSS can be a more specific sign in the imaging diagnosis of abscesses. • ILSS of SWI can contribute to differential diagnosis of rim-enhanced mass. • Low-grade ILSS can be a more specific sign in abscesses. • High-grade ILSS may help distinguish necrotic glioblastomas from abscesses. • ILSS spreads across the four ILSS categories in metastases.

Role of diffusion weighted imaging and proton magnetic resonance spectroscopy in ring enhancing brain lesions

Aim of the workTo assess and compare the usefulness and efficacy of both diffusion weighted imaging (DWI) and proton magnetic resonance spectroscopy (1HMRS) in brain lesions with ring enhancement in post contrast T1WI and to determine which method is more effective. Subjects and methodsThirty patients with ring-enhanced brain lesions were classified into 2 groups, abscess group (11 patients) and tumor group (19 patients), were examined using diffusion-weighted imaging (DWI) and H-proton magnetic resonance spectroscopy (1HMRS). ResultsRestricted diffusion and low ADC value were seen in 9 (81%) patients of brain abscesses, however, free diffusion and high ADC value were found in 18 (94%) patients with necrotic brain tumor. The abscess group showed aminoacids, acetate and lactate in 9 patients and extra peak of succinate was found in 1 patient; however in the tumor group lactate alone was found in 12 patients, lactate and choline were seen in 5 patients, none of the patients showed amino acids, succinate or acetate. ConclusionBoth DWI and 1HMRS are useful and efficient imaging techniques in ring enhancing brain lesions and differentiate between pyogenic brain abscesses and necrotic tumors, but DWI is accurate, has less imaging time than 1HMRS, also is available in many imaging centers.

Role of diffusion-weighted MR imaging in discrimination between the intracranial cystic masses

ObjectiveDiscriminating pyogenic brain abscesses from cystic or necrotic tumors is sometimes difficult with CT or conventional MR imaging. Diffusion MR imaging is a valuable diagnostic test in cases of intracranial cystic masses. MethodsThis work was conducted from July 2008 to June 2013 on 90 patients; 43 males and 47 females. Their ages range from 5 to 70years. All patients were subjected to routine MRI examination and diffusion weighted imaging using 1.5T MRI scanner. Gadolinium was given to some cases on routine MRI. Diffusion weighted imaging was performed with a single-shot spin-echo echo-planar pulse sequence (b=0–1000s/mm2). The apparent diffusion coefficient values and ratio were measured. Results and conclusionsPatients in this study were categorized into three main groups; first group is brain abscesses (36 cases), 91.6% of them showed restricted diffusion, second group is malignant cystic or necrotic brain tumors, 28 cases of high grade necrotic glioma, 60.7% of them are free diffusion, and third group is benign cystic masses, arachnoid and epidermiod cysts (11 cases); all arachnoid cysts are free diffusion. From these results diffusion-weighted imaging is playing an important role in discrimination of cystic intracranial masses.

Solitary tuberculous brain lesions: 24 new cases and a review of the literature

A solitary tuberculous brain lesion (STBL) can be difficult to distinguish from a glioma, metastasis or other infectious disease, especially from a pyogenic brain abscess. We analyzed the clinical characteristics, diagnostic procedures and outcomes of 24 patients with STBL diagnosed in three centers from France, India and Mexico. We also reviewed 92 STBL cases previously reported in the literature. General symptoms were found in 54% of our patients, including enlarged lymph nodes in 20%. Cerebrospinal fluid was typically abnormal, with lymphocytic pleocytosis and a high protein level. The lung CT scan was abnormal in 56% of patients, showing lymphadenopathy or pachipleuritis. Brain MRI or CT was always abnormal, showing contrast-enhanced lesions. Typically, MRI abnormalities were hypointense on T1-weighted sequences, while T2-weighted sequences showed both a peripheral hypersignal and a central hyposignal. The diagnosis was documented microbiologically or supported histologically in 71% of cases. Clinical outcome was good in 83% of cases.

1H proton MR spectroscopy and diffusion-weighted imaging in discrimination between pyogenic brain abscesses and necrotic brain tumors

BackgroundDifferentiation between cerebral abscesses and necrotic brain tumors showing ring enhancement can be confusing at times by conventional MRI. The introduction of advanced imaging techniques, such as MR spectroscopy and diffusion WI, have contributed to the differentiation.The purpose of this study is to test the hypothesis that MR spectroscopy and diffusion weighted can be used to differentiate between necrotizing or cystic brain tumor and brain abscesses. MethodsThe study was conducted on 45 patients (necrotic or cystic tumor (30 cases); brain abscess (15 cases) showing ring-shaped contrast enhancement on conventional MRI. 1.5-T 1H-MR Spectroscopy and diffusion WI were performed and the results were ensured by stereotactic biopsy or aspiration procedures in surgically indicated cases and/or follow up. Results14 patients (out of 15) with pyogenic abscess had lactate, amino acids, and acetate peaks; Succinate peak is seen as extra peak in three of these patients, and lipid peaks are also seen as extra peaks in 3 patients. One patient with brain stem abscess after 20days treatment by antibiotics shows only lactate and lipid peaks. 2 of them show mild increase in choline with decrease in NAA (brain tissue contamination).17 out of 30 patients with cystic or necrotic tumor showed only lactate peak in MRS. While 13 patients show lactate and lipid peaks, four of them show additional high choline peak with low NAA and creatine peak (contamination with brain tissue).The results were confirmed by Sterotactic biopsy in 27 cases and aspiration in 13 cases and follow up for all cases.The sensitivity, specificity, PPV, NPV and overall accuracy of diffusion and MRS were 88%, 100%, 100%, 93.3% and 95.5% respectively. Conclusion1H-MRS and diffusion WI are fast, easy to perform, noninvasive, and provide additional information that can accurately differentiate between necrotic/cystic tumors and cerebral abscesses.

Multimodal approach for diagnosis of bacterial etiology in brain abscess

Background and purposeProton magnetic resonance spectroscopy (PMRS) has high sensitivity and specificity for the detection of pyogenic brain abscess and the categorization of bacteria. But the metabolite patterns failed to evaluate the etiology of disease when the culture results are sterile. The aim of the present study is to compare the multimodality techniques viz., conventional culture, MR spectroscopy and 16S rRNA PCR and sequencing for rapid diagnosis of etiology in brain abscess and evaluate the PMRS in culture sterile samples and also demonstrate the sensitivity and specificity of these techniques. MethodsThirty five patients underwent MRI on a 3T MRI and in-vivo PMRS for the diagnosis and evaluation of various resonances of metabolites such as lipid (LIP), lactate (LAC), acetate (AC), amino acid (AC), succinate (SUC). Pus was collected for identification of etiologic agents by culture and molecular method. ResultsIn 35 samples, metabolite patterns were as follows: LIP/LAC/AA, n=17, LIP/LAC/AA/SUC with or without AC, n=17 and LIP/LAC/AA/AC, n=1. Culture showed bacterial growth in 22 samples (18 aerobic/facultative anaerobic, 9 anaerobic) whereas molecular method was detected 26 aerobic/facultative anaerobic, 13 anaerobic, 4 microaerophilic bacteria. Among the 13 sterile samples, molecular method detected 16 microorganisms along with 3 mixed infections and PMRS recognized metabolite patterns as LIP/LAC/AA, n= 5 and LIP/LAC/AA/SUC with or without AC, n=8. The sensitivity of in-vivo PMRS in sterile samples was 100% and 75%, and specificity was 75% and 100% for aerobic and anaerobic organisms respectively. ConclusionBased on metabolite resonances, PMRS can detect slow growing and fastidious organisms and classify them into aerobic and anaerobic bacteria which are difficult to culture by conventional method. It can categorize microorganisms even in culture sterile samples with rational sensitivity and specificity which may allow early choice of targeted therapy.