Lymphocytic choriomeningitis virus meningoencephalitis in a renal transplant recipient following exposure to mice.

Solid organ transplant recipients (SOTR) are at increased risk for a wide variety of typical and atypical infections as a consequence of impaired cell mediated and humoral immunity. We report a case of meningoencephalitis in a renal transplant recipient caused by lymphocytic choriomeningitis virus (LCMV) acquired by exposure to mice excreta. The clinical course was complicated by the development of hydrocephalus, requiring a ventriculoperitoneal shunt. To our knowledge, this is the first reported case of LCMV infection in a SOTR that was not organ donor derived.

Lack of effect of antibiotics on biopsy culture results in vertebral osteomyelitis.

We report a retrospective study of 173 patients with vertebral osteomyelitis evaluating the effect of antibiotics administered prior to percutaneous and open biopsy cultures. Antibiotics given prior to these biopsies did not have a significant effect on the yield of cultures.

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.

Decreasing incidence of Staphylococcus aureus bacteremia over 9 years: greatest decline in community-associated methicillin-susceptible and hospital-acquired methicillin-resistant isolates.

BACKGROUND: The impact of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) emergence on the epidemiology of S aureus bacteremia (SAB) is not well documented. METHODS: This was an observational study of adult (aged ≥18 years) inpatients with SAB in a single 808-bed teaching hospital during 2002-2003, 2005-2006, 2008-2009, and 2010 with period-stratified SAB rate, onset mode, patient characteristics, and outcome. RESULTS: We encountered a total of 1,098 cases over the entire study period. The rate decreased steadily over time (from 6.64/10(3) discharges in 2002-2003 to 6.49/10(3) in 2005-2006, 5.24/10(3) in 2008-2009, and 5.00/10(3) in 2010; P = .0001), with a greater decline in community-associated cases (0.99/10(3), 0.77/10(3), 0.58/10(3), and 0.40/10(3), respectively; P = .0005) compared with health care-associated cases (5.65/10(3), 5.72/10(3), 4.66/10(3), and 4.60/10(3), respectively; P = .005). The decline was principally in MSSA (3.11/10(3), 2.21/10(3), 2.24/10(3), and 1.75/10(3), respectively; P = .00006), including both community-associated (P = .0002) and health care-associated cases (P = .006). Although overall rate changes in MRSA were not significant (P = .09), hospital-onset MRSA decreased markedly (P < .00001), whereas CA-MRSA increased (P = .03). The all-cause 100-day mortality rate did not change significantly (25.6% for 2002-2003, 25.2% for 2005-2006, 28.1% for 2008-2009, and 32.2% for 2010; P = .10). Differences in MSSA/MRSA-associated mortality decreased (20.1% vs 30.6%, P = .03 for 2002-2003; 18.1% vs 28.9%, P = .05 for 2005-2006; 21.7% vs 32.9%, P = .05 for 2008-2009; and 29.3% vs 34.9, P = .5 for 2010). CONCLUSIONS: SAB incidence is decreasing, with the greatest decline in community-associated MSSA and hospital-onset MRSA cases. Most health care-associated cases currently are community-onset. MRSA/MSSA-related mortality is comparable. These changes are likely related to the emergence of CA-MRSA and the inpatient-to-outpatient shift in health care.

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.

Treatment of Acinetobacter infections.

Acinetobacter baumannii remains an important and difficult-to-treat pathogen whose resistance patterns result in significant challenges for the clinician. Despite the prevalence and interest in A. baumannii infections, there is relatively limited well-controlled scientific data to help the clinician select optimal empirical and subsequent targeted therapy for a variety of infections. We will review the currently available antimicrobial agents and discuss the clinical data supporting the use of the various agents.

Antibiotic resistance determinants in Acinetobacter spp and clinical outcomes in patients from a major military treatment facility.

We explored the association of antibiotic-resistant phenotypes and genotypes in Acinetobacter spp with clinical outcomes and characteristics in 75 patients from a major military treatment facility. Amikacin resistance was associated with nosocomial acquisition of A baumannii, and carbapenem resistance and bla(OXA-23) were associated with the need for mechanical ventilation. The presence of bla(OXA-23) also correlated with longer hospital and ICU stay. Associations between bla(OXA-23) and complexity, duration, and changes made to antibiotic regimens also existed.

An outbreak of multidrug-resistant Acinetobacter baumannii-calcoaceticus complex infection in the US military health care system associated with military operations in Iraq.

BACKGROUND: We investigated an outbreak of multidrug-resistant Acinetobacter baumannii-calcoaceticus complex infection among US service members injured in Iraq. METHODS: The investigation was conducted in Iraq and Kuwait, in the 2 military hospitals where the majority of injured service members were initially treated. After initially characterizing the outbreak, we evaluated 3 potential sources of infection for the period March 2003 to December 2004. The evaluation included screening samples that were obtained from the skin of patients for the presence of colonization and assessing the soil and health care environments for the presence of A. baumanii-calcoaceticus complex organisms. Isolates obtained from samples from patients in US Military treatment facilities, as well as environmental isolates, were genotypically characterized and compared using pulsed-field gel electrophoresis. RESULTS: A. baumanii-calcoaceticus complex organisms were present on the skin in only 1 (0.6%) of 160 patients who were screened and in 1 (2%) of 49 soil samples. A. baumanii-calcoaceticus complex isolates were recovered from treatment areas in 7 of the 7 field hospitals sampled. Using pulsed-field gel electrophoresis, we identified 5 cluster groups in which isolates from patients were related to environmental isolates. One cluster included hospitalized patients who had not been deployed to Iraq. Among the clinical isolates, only imipenem, polymyxin B, and colistin demonstrated reliable in vitro antimicrobial activity. Generally, the environmental isolates were more drug susceptible than were the clinical isolates. CONCLUSIONS: Our findings suggest that environmental contamination of field hospitals and infection transmission within health care facilities played a major role in this outbreak. On the basis of these findings, maintaining infection control throughout the military health care system is essential. Novel strategies may be required to prevent the transmission of pathogens in combat field hospitals.

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.

Identification of Acinetobacter species and genotyping of Acinetobacter baumannii by multilocus PCR and mass spectrometry.

Members of the genus Acinetobacter are ubiquitous in soil and water and are an important cause of nosocomial infections. A rapid method is needed to genotype Acinetobacter isolates to determine epidemiology and clonality during infectious outbreaks. Multilocus PCR followed by electrospray ionization mass spectrometry (PCR/ESI-MS) is a method that uses the amplicon base compositions to genotype bacterial species. In order to identify regions of the Acinetobacter genome useful for this method, we sequenced regions of six housekeeping genes (trpE, adk, efp, mutY, fumC, and ppa) from 267 isolates of Acinetobacter. Isolates were collected from infected and colonized soldiers and civilians involved in an outbreak in the military health care system associated with the conflict in Iraq, from previously characterized outbreaks in European hospitals, and from culture collections. Most of the isolates from the Iraqi conflict were Acinetobacter baumannii (189 of 216 isolates). Among these, 111 isolates had genotypes identical or very similar to those associated with well-characterized A. baumannii isolates from European hospitals. Twenty-seven isolates from the conflict were found to have genotypes representing different Acinetobacter species, including 8 representatives of Acinetobacter genomospecies 13TU and 13 representatives of Acinetobacter genomospecies 3. Analysis by the PCR/ESI-MS method using nine primer pairs targeting the most information-rich regions of the trpE, adk, mutY, fumC, and ppa genes distinguished 47 of the 48 A. baumannii genotypes identified by sequencing and identified at the species level at least 18 Acinetobacter species. Results obtained with our genotyping method were essentially in agreement with those obtained by pulse-field gel electrophoresis analysis. The PCR/ESI-MS genotyping method required 4 h of analysis time to first answer with additional samples subsequently analyzed every 10 min. This rapid analysis allows tracking of transmission for the implementation of appropriate infection control measures on a time scale previously not achievable.

Comparison of Acinetobacter baumannii isolates from the United Kingdom and the United States that were associated with repatriated casualties of the Iraq conflict.

Acinetobacter isolates associated with casualties from the Iraq conflict from the United States were compared with those from the United Kingdom by pulsed-field gel electrophoresis and integron analysis. Representatives of the main outbreak strain associated with casualties from both countries were indistinguishable in DNA profile. Two further outbreak strains were common to both sets of isolates.

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.