MALDI-TOF identification of Gram-negative bacteria directly from blood culture bottles containing charcoal: Sepsityper® kits versus centrifugation-filtration method.

Matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry has dramatically altered the way microbiology laboratories identify clinical isolates. Direct blood culture (BC) detection may be hampered, however, by the presence of charcoal in BC bottles currently in clinical use. This study evaluates an in-house process for extraction and MALDI-TOF identification of Gram-negative bacteria directly from BC bottles containing charcoal. Three hundred BC aliquots were extracted by a centrifugation-filtration method developed in our research laboratory with the first 96 samples processed in parallel using Sepsityper® kits. Controls were colonies from solid media with standard phenotypic and MALDI-TOF identification. The identification of Gram-negative bacteria was successful more often via the in-house method compared to Sepsityper® kits (94.7% versus 78.1%, P≤0.0001). Our in-house centrifugation-filtration method was further validated for isolation and identification of Gram-negative bacteria (95%; n=300) directly from BC bottles containing charcoal.

Use of portable electronic devices in a hospital setting and their potential for bacterial colonization.

Portable electronic devices are increasingly being used in the hospital setting. As with other fomites, these devices represent a potential reservoir for the transmission of pathogens. We conducted a convenience sampling of devices in 2 large medical centers to identify bacterial colonization rates and potential risk factors.

Invasive Bordetella holmesii infections.

Bordetella holmesii is a rare cause of invasive human disease. The fastidious and unusual nature of this organism makes routine isolation and identification challenging. We report two cases of B. holmesii bacteremia that were rapidly identified by matrix-assisted laser desorption-ionization time-of-flight mass spectrometry (MALDI-TOF MS) when standard techniques failed to provide speciation. There are no current standards for susceptibility testing or treatment recommendations. The rare occurrence and challenges in identifying this pathogen led us to perform a comprehensive review of the epidemiology, clinical presentations, and treatment options for this potentially invasive pathogen.

Clinical value of chest computerized tomography scans in patients admitted with pneumonia.

Patients admitted with pneumonia often receive a chest computed tomography (CT) scan for a variety of reasons. We conducted this study to evaluate our overall utilization and the clinical impact of CT scans in patients admitted to our institution with pneumonia. Patients admitted to our facility from January 2008 through November 2011 with a confirmed diagnosis of pneumonia were eligible for evaluation. Information related to patient demographics, performance of a CT scan, pneumonia-related procedures, severity of illness, and outcomes was collected. One hundred ninety-five patients met inclusion criteria. Sixty-nine patients had CT scans performed. CT scans were performed more often in younger patients (58.1 ± 19.0 vs 66.8 ± 18.6, P = 0.002), individuals with lower CURB 65 (Confusion, Urea, Respiratory rate, Blood pressure, Age > 65) scores (1.7 ± 1.4 vs 2.2 ± 1.4, P = 0.037), and those with no infiltrates or consolidation on plain radiographs (26.9% vs 7.1%, P < 0.0001). Patients who had a procedure performed had longer average length of stays (15.3 ± 11.9 vs 6.8 ± 4.1 days, P = 0.016). Pneumonia-related procedures were more likely performed in patients who had a CT scan. Specific guidelines and objective rules need to be developed to prospectively guide the use of advanced imaging techniques in pneumonia patients.

The role of intravenous catheters in cardiovascular implantable electronic device infections: identifying potential targets for prevention.

Infections related to cardiac implantable electronic devices (CIEDs) are increasing in prevalence and carry substantial morbidity and mortality. Complications involving peripheral intravenous catheters resulting in CIED infections have not yet been investigated and may pose an important risk factor. We report 5 cases of CIED infection related to documented complications of peripheral vascular devices.

Detection of extended-spectrum ß-lactamase and Klebsiella pneumoniae Carbapenemase genes directly from blood cultures by use of a nucleic acid microarray.

The growing crisis of multidrug-resistant (MDR) Gram-negative bacteria requires that current technologies permit the rapid detection of extended-spectrum ß-lactamase (bla(ESBL)) and Klebsiella pneumoniae carbapenemase (bla(KPC)) genes. In the present study, we assessed the performance characteristics of a commercially available nucleic acid microarray system for the detection of bla(ESBL) and bla(KPC) genes directly from positive blood cultures. Using blood cultures (BCs) that contained Gram-negative bacilli identified by Gram staining, we isolated bacterial DNA using spin columns (BC-C) and rapid water lysis (BC-W). Twenty ESBL/KPC-positive and 20 ESBL/KPC-negative blood culture samples, as well as 20 non-lactose-fermenting organisms, were tested. The 20 isolates that were ESBL positive by phenotypic testing were also evaluated on solid medium (SM), and the DNA was extracted by use of a spin column (SM-C). The resulting 140 DNA extractions were assessed for DNA quantity and quality using 260/280-nm absorbance ratios, and DNA microarray analysis was performed in a blinded fashion. Microarray and phenotypic results were concordant for 98.3% of BC-W, 90% of BC-C, and 95% of SM-C samples. Compared to phenotypic testing, the sensitivity and specificity for BC-C samples were 88.9% and 100%, respectively, and for BC-W samples, the sensitivity and specificity were 94.4% and 100%, respectively. BC-W samples yielded the highest concordance with phenotypic results. Nucleic acid microarrays offer promise in the identification of bla(ESBL) and bla(KPC) genes directly from blood cultures, thereby reducing the time to identification of these important pathogens.

Analysis of antibiotic resistance genes in multidrug-resistant Acinetobacter sp. isolates from military and civilian patients treated at the Walter Reed Army Medical Center.

Military medical facilities treating patients injured in Iraq and Afghanistan have identified a large number of multidrug-resistant (MDR) Acinetobacter baumannii isolates. In order to anticipate the impact of these pathogens on patient care, we analyzed the antibiotic resistance genes responsible for the MDR phenotype in Acinetobacter sp. isolates collected from patients at the Walter Reed Army Medical Center (WRAMC). Susceptibility testing, PCR amplification of the genetic determinants of resistance, and clonality were determined. Seventy-five unique patient isolates were included in this study: 53% were from bloodstream infections, 89% were resistant to at least three classes of antibiotics, and 15% were resistant to all nine antibiotics tested. Thirty-seven percent of the isolates were recovered from patients nosocomially infected or colonized at the WRAMC. Sixteen unique resistance genes or gene families and four mobile genetic elements were detected. In addition, this is the first report of bla(OXA-58)-like and bla(PER)-like genes in the U.S. MDR A. baumannii isolates with at least eight identified resistance determinants were recovered from 49 of the 75 patients. Molecular typing revealed multiple clones, with eight major clonal types being nosocomially acquired and with more than 60% of the isolates being related to three pan-European types. This report gives a "snapshot" of the complex genetic background responsible for antimicrobial resistance in Acinetobacter spp. from the WRAMC. Identifying genes associated with the MDR phenotype and defining patterns of transmission serve as a starting point for devising strategies to limit the clinical impact of these serious infections.

Nocardia kruczakiae sp. nov., a pathogen in immunocompromised patients and a member of the "N. nova complex".

Molecular methodologies have become useful techniques for the identification of pathogenic Nocardia species and for the recognition of novel species that are capable of causing human disease. Two isolates recovered from immunocompromised patients were characterized as Nocardia nova by biochemical and susceptibility testing results. The restriction fragment length polymorphism (RFLP) patterns obtained by restriction endonuclease analysis (REA) of an amplified portion of the heat shock protein gene were identical to those obtained with the type strain of N. nova. REA of an amplified portion of the 16S rRNA gene showed RFLP patterns that were unlike those obtained for the type strain of N. nova but that were similar to those obtained for the type strains of N. africana and N. veterana. Subsequent sequencing of a portion of the 16S rRNA gene produced identical results for the two patient isolates. Sequence analysis of 1,352-bp portions of the 16S rRNA gene indicated that these isolates were 99.8% similar to the recently described species N. veterana but were only 99.3, 98.1, and 98.1% similar to the type strains of N. africana, N. nova, and N. vaccinii, respectively. DNA-DNA hybridization studies confirmed that the two patient isolates belonged to the same species but were not closely related to N. africana, N. nova, N. vaccinii, or N. veterana. The patient isolates have been designated N. kruczakiae sp. nov. Because N. africana, N. veterana, and the new species are not readily differentiated from N. nova by phenotypic methods alone, the designation "N. nova complex" can be used to designate isolates such as these that phenotypically resemble N. nova but that have not been definitively characterized by 16S rRNA gene sequencing or DNA-DNA hybridization.

Aerosolized biologic toxins as agents of warfare and terrorism.

Incomplete participation in the 1972 Biological Weapons Convention treaty and noncompliance by several signatory nations makes the malicious use of aerosolized biologic toxins a continuing threat. Unfortunately,prompt diagnosis of toxin exposure may be confounded by a paucity of pathognomonic features and limited diagnostics, but the scenario of patients presenting en masse with a similar pulmonary syndrome should alert the clinician to the possibility of aerosolized toxin exposure. As knowledge of these agents increases, so too should the capabilities for detection,protection, diagnosis, and therapy. This improved understanding, coupled with ongoing public education and awareness and with detailed proactive planning will provide the framework for a prepared community.

Eosinophilic meningitis: a case series report and review of the literature.

Prompted by a case of eosinophilic meningitis (EM), a review of the literature was performed to evaluate the strength of the diagnoses associated with EM and compares these results with our hospital's experience. Articles were critically reviewed for supporting evidence, method of diagnosis, and established standards for specific diagnosis. EM has been defined as > or = 10 eosinophils per mm3 or > or = 10% eosinophils of total cell count. Sixty-two cases of EM were found at our institution and reviewed. The results of this case series review concur with those found in the literature. It also suggests the importance of considering infectious and noninfectious etiologies when faced with eosinophils in the cerebrospinal fluid. This review and case study analysis provides the clinician with a critically established set of differential diagnoses and a concise definition of EM that may assist the physician in the evaluation of patients presenting with eosinophils in the cerebrospinal fluid.

Nosocomial transmission of methicillin-resistant Staphylococcus aureus: a blinded study to establish baseline acquisition rates.

OBJECTIVE: To define the extent of nosocomial transmission of methicillin-resistant Staphylococcus aureus (MRSA) in patients admitted to a tertiary-care hospital. DESIGN: A blinded, prospective surveillance culture study of patients admitted to the hospital to determine the transmission (acquisition) rate of MRSA. Risk factors associated with the likelihood of MRSA colonization on admission were investigated. SETTING: Tertiary-care military medical facility. PARTICIPANTS: All patients admitted to the medicine, surgery, and pediatric wards, and to the medical, surgical, and pediatric intensive care units were eligible for inclusion. RESULTS: Five hundred thirty-five admission and 374 discharge samples were collected during the study period. One hundred forty-one patients were colonized with methicillin-susceptible S. aureus (MSSA) and 20 patients (3.7%) were colonized with MRSA on admission. Of the 354 susceptible patients, 6 acquired MRSA during the study for a transmission rate of 1.7%. Patients colonized with MRSA on admission were more likely to be older than non-colonized or MSSA-colonized patients, to have received antibiotics within the past year, to have been hospitalized within the prior 3 years, or to have a known history of MRSA. Patients acquiring MRSA had an average hospital stay of 17.7 days compared with 5.3 days for those who did not acquire MRSA. Pulsed-field gel electrophoresis of the 6 MRSA isolates from patients who acquired MRSA revealed 4 distinct band patterns. CONCLUSIONS: Most patients colonized with MRSA were identified on admission samples. Surveillance cultures of patients admitted may help to prevent MRSA transmission and infection.

Tuberculous tenosynovitis of the tibialis anterior tendon: a case report.

Tuberculous tenosynovitis is an uncommon form of extrapulmonary tuberculosis occurring primarily in the hands and wrists with limited reports involving the lower extremities. We report a rare case of tuberculous tenosynovitis of the tibialis anterior tendon occurring in a 37-year-old Filipino male. The tendon was surgically debrided and the patient was given a six month course of antituberculin chemotherapy. At one year postoperatively, the patient has good function with no evidence of recurrence.

Surveillance for methicillin-resistant Staphylococcus aureus in Battambang, Cambodia.

Methicillin-resistant Staphylococcus aureus (MRSA) and humanitarian missions are increasing worldwide. The prevalence of MRSA in the populations served may be unknown. A BRAVA (Blast Resuscitlation and Victim Assistance) mission was conducted at Battambang, Cambodia that included microbiology support. No MRSA was detected in our patients despite the reported increase in MRSA in Asia. Continued investigation is warranted for future missions.

Empiric immunization versus serologic screening: developing a cost-effective strategy for the use of hepatitis A immunization in travelers.

BACKGROUND: Older individuals and those born overseas are thought at increased risk of prior exposure and thus have naturally acquired immunity to hepatitis A. Whether these individuals or other groups of international travelers should be screened for acquired immunity or empirically immunized is not clear. Hepatitis A serology and risk factor data was obtained prospectively in patients presenting for hepatitis A immunization and used to develop a cost-effective strategy for the use of serologic screening and empiric immunization in our traveler population. METHOD: Candidates for hepatitis A immunization were routinely screened for total hepatitis A serum antibody. Risk factor data including country of birth, travel history, and history of jaundice was collected. Cost-effectiveness was assessed by comparing the cost of serology to screen all patients plus cost to immunize those found to be seronegative with, the cost of empirically immunizing all patients. RESULTS: Analyses were conducted comparing age, travel history, country of birth, and history of jaundice for significance in predicting seropositivity in a group of 115 subjects. Country of birth was statistically a significant predictor of positive results with 80.0% of foreign-born patients positive for total antibody against hepatitis A compared with 35.6% of patients born in the United States. Living outside of the United States (defined as greater than 30 days) was also correlated with a higher prevalence of hepatitis A positive serology. Age was not predictive for the group as a whole. A lower prevalence (24.3%) was noted in the group of US born individuals aged 30 to 60. Travel and prior history of jaundice failed to demonstrate significance. CONCLUSIONS: Employing a simple cost-effectiveness equation using cost of serological testing, cost of vaccine, and prevalence of acquired immunity in the community, a strategy was developed. In our population it was cost-effective to screen all foreign-born individuals and those who had lived outside the United States.