Multicenter Evaluation of Ceftazidime-Avibactam Susceptibility Testing of Enterobacterales and Pseudomonas aeruginosa on the Vitek 2 System.

In this multisite study, Vitek 2 AST-Gram-Negative Ceftazidime/Avibactam test results for 1,073 isolates (866 Enterobacterales and 207 Pseudomonas aeruginosa) were compared to the Clinical and Laboratory Standards Institute (CLSI) broth microdilution (BMD) reference method. The results were analyzed for essential agreement (EA), category agreement (CA), major error rates, and very major error rates following FDA/ISO performance criteria using the FDA-recognized CLSI/EUCAST breakpoints (sensitive [S], ≤8/4 µg/ml; resistant [R], ≥16/4 µg/ml). The overall EA was 94.5% (1,014/1,073) and CA was 98.7% (1,059/1,073). No very major errors were reported. The major error rate was 1.4% (14/998). Out of 14 major errors, 9 were within EA. Based on the EA and lack of an intermediate category for ceftazidime-avibactam (CZA), the adjusted major error rate for FDA criteria was 0.5% (5/998). The performance for ISO criteria after error resolutions included EA of 94.5% (1,014/1,073), CA of 98.9% (1,061/1,073), major error of 1.2% (12/998), and no very major error. Vitek 2 met the ISO and FDA criteria of ≥95% reproducibility and ≥95% quality control (QC) results within acceptable ranges for QC organisms. Vitek 2 overall performance for Enterobacterales and P. aeruginosa met or exceeded the FDA and ISO performance criteria; thus, it is a reliable alternative to the BMD reference method for routine CZA susceptibility testing.

Multicenter evaluation of the RAPIDEC® CARBA NP assay for the detection of carbapenemase production in clinical isolates of Enterobacterales and Pseudomonas aeruginosa.

Carbapenem-resistant Gram-negative bacilli are a major public health problem. Accurate and rapid detection of carbapenemase-producing organisms can facilitate appropriate infection prevention measures. The objective was to evaluate the performance of the RAPIDEC® CARBA NP assay (RAPIDEC), a screening assay that utilizes a pH indicator to detect carbapenem hydrolysis within 2 h. A multicenter study evaluated 306 clinical bacterial strains of Enterobacterales (n = 257) and Pseudomonas aeruginosa (n = 49). The RAPIDEC was compared to a composite reference standard-the Clinical Laboratory Standards Institute (CLSI) Carba NP assay, PCR for specific carbapenemase genes (blaKPC, blaNDM, blaOXA-48-like, blaVIM and blaIMP), and phenotypic carbapenem susceptibility testing. The assay was evaluated using two culture incubation times for the bacterial isolates: "routine"(cultures incubated 18-24 h) and "short" (cultures incubated 4-5 h). For the routine incubation, the overall percent agreement was 98.7% with a positive percent agreement (PPA) of 99.6% and a negative percent agreement (NPA) of 97.4%; there were five false positives and one false negative. For the short incubation, the overall percent agreement was 98.0% with a PPA of 98.5% and a NPA of 97.3%; there were five false positives and four false negatives. RAPIDEC results for the P. aeruginosa isolates were 100% concordant with the reference standard for both incubation times. The RAPIDEC assay is an accurate and rapid (≤ 2 h) assay for the detection of the most common carbapenemases in clinical isolates. Growth from a short incubation culture may be used to reliably detect carbapenemase production in clinical strains.

Evaluation of Remel Spectra CRE Agar for Detection of Carbapenem-Resistant Bacteria from Rectal Swabs Obtained from Residents of a Long-Term-Care Facility.

We compared the Remel Spectra CRE agar plate to CDC standard methodology for the isolation of carbapenem-resistant Enterobacteriaceae (CRE) from 300 rectal swab specimens obtained from patients residing in a long-term-care facility (LTCF). Multiplex PCR experiments were performed on isolates to identify specific Klebsiella pneumoniae carbapenemases (KPC) and additional ß-lactamases. Of the 300 patients, 72 (24%) harbored CRE and were PCR positive for KPC enzymes. The Remel Spectra CRE plates detected KPC-type CRE in isolates from 70 of 72 patients (97.2%), while the CDC method detected CRE in 56 of 72 (77.8%). CRE identification results were available in 18 h compared to 36 h for the CDC method. Remel Spectra CRE agar plates can provide useful means for a fast and reliable method for detecting KPC-type CRE and for accelerated institution of appropriate infection control precautions.

Phellinus tropicalis abscesses in a patient with chronic granulomatous disease.

Chronic Granulomatous Disease (CGD), caused by genetic defects in components of the phagocyte NADPH oxidase pathway, leads to recurrent life-threatening bacterial and invasive fungal infections. While a number of unique pathogens have been associated with this disease, the causative organisms may be difficult to identify. Here, we present a 24 year old male with known X-linked CGD who concurrently developed a cervical abscess and an abscess in the subcutaneous tissues of the right hip, both of which were surgically drained. Cultures failed to identify any organisms. He was treated empirically with ertapenem but the hip abscess recurred at the original site and in contiguous dependent areas in the posterior thigh and knee. A filamentous organism was observed microscopically, initially considered a contaminant, but on culture yielded a mold growth, identified as Phellinus tropicalis (synonym: Inonotus tropicalis) based on phenotypic and molecular methods. This is the third case report of human infection with P. tropicalis, all in subjects with CGD. The patient was treated with voriconazole with resolution of his symptoms.

The prepped vaginal canal may be a sterile conduit for ventral hernia mesh insertion: a prospective comparative study.

BACKGROUND: Although still experimental, natural orifice translumenal endoscopic surgery (NOTES) aims to use the natural orifices for intraabdominal surgery. Pure transvaginal umbilical hernia repair has been reported. However, mesh protection devices were used to minimize mesh contamination during mesh insertion. The authors believe that before widespread implementation of this technique, more foundational research is indicated to establish the sterility of hernia mesh insertion through this route. This prospective study aimed to compare transvaginal ventral hernia mesh insertion sterility with laparoscopic trocar-site insertion sterility to establish baseline data to help promote the safety of NOTES tranvaginal hernia repair. METHODS: This was a prospective descriptive study (Canadian Task Force classification 2A). With institutional review board approval, 10 patients undergoing laparoscopic surgery for benign gynecologic disease were enrolled in the study. Atrium Prolite mesh (polypropylene monofilament) was inserted into the vagina before and after standard surgical preparation with 10 % povidone­iodine. As a control, mesh also was inserted through a prepped laparoscopic port site. The mesh was cultured for bacterial, fungal, and viral contamination. All patients received standard infection prophylaxis that included preoperative intravenous cefazolin and metronidazole. RESULTS: The unprepped vaginal canal was cultured and demonstrated normal multiorganism vaginal flora in all 10 cases. Of the 10 skin incision mesh samples, 3 (30 %) grew bacteria, including Staphylococcus lugdunensis, a potentially pathogenic organism. In contrast, none of the prepped vaginal mesh specimens yielded any growth of microorganisms or potential pathogens. CONCLUSIONS: This study showed that a surgically prepped vaginal canal can be a sterile conduit for insertion of polypropylene mesh for transvaginal ventral hernia repair without the use of additional mesh protection. Surprisingly, the prepped vaginal conduit in our patients was more sterile than a prepped skin incision.

Detection of colonization by carbapenemase-producing Gram-negative Bacilli in patients by use of the Xpert MDRO assay.

Detecting colonization of patients with carbapenemase-producing bacteria can be difficult. This study compared the sensitivity and specificity of a PCR-based method (Xpert MDRO) for detecting blaKPC, blaNDM, and blaVIM carbapenem resistance genes using GeneXpert cartridges to the results of culture with and without a broth enrichment step on 328 rectal, perirectal, and stool samples. The culture method included direct inoculation of a MacConkey agar plate on which a 10-µg meropenem disk was placed and plating on MacConkey agar after overnight enrichment of the sample in MacConkey broth containing 1 µg/ml of meropenem. Forty-three (13.1%) samples were positive by PCR for blaKPC and 11 (3.4%) were positive for blaVIM; none were positive for blaNDM. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the PCR assay for blaKPC were 100%, 99.0%, 93.0%, and 100%, respectively, compared to broth enrichment culture and sequencing of target genes. The sensitivity, specificity, PPV, and NPV of the assay for blaVIM were 100%, 99.4%, 81.8%, and 100%, respectively. Since none of the clinical samples contained organisms with blaNDM, 66 contrived stool samples were prepared at various dilutions using three Klebsiella pneumoniae isolates containing blaNDM. The PCR assay showed 100% positivity at dilutions from 300 to 1,800 CFU/ml and 93.3% at 150 CFU/ml. The Xpert MDRO PCR assay required 2 min of hands-on time and 47 min to complete. Rapid identification of patients colonized with carbapenemase-producing organisms using multiplex PCR may help hospitals to improve infection control activities.

Susceptibility of gram-negative pathogens isolated from patients with complicated intra-abdominal infections in the United States, 2007-2008: results of the Study for Monitoring Antimicrobial Resistance Trends (SMART).

During 2007-2008, 1,036 gram-negative bacilli were isolated from patients with complicated intra-abdominal infections in the United States. Against members of the family Enterobacteriaceae, the most active agents in vitro were ertapenem, imipenem, and amikacin, while the least active agent was ampicillin-sulbactam. Ertapenem and imipenem were active against all extended-spectrum-beta-lactamase (ESBL)-positive Escherichia coli. Antimicrobial resistance in gram-negative bacilli isolated from patients with complicated intra-abdominal infections in the United States continues to increase.

Comparison of meropenem MICs and susceptibilities for carbapenemase-producing Klebsiella pneumoniae isolates by various testing methods.

We describe the levels of agreement between broth microdilution, Etest, Vitek 2, Sensititre, and MicroScan methods to accurately define the meropenem MIC and categorical interpretation of susceptibility against carbapenemase-producing Klebsiella pneumoniae (KPC). A total of 46 clinical K. pneumoniae isolates with KPC genotypes, all modified Hodge test and bla(KPC) positive, collected from two hospitals in NY were included. Results obtained by each method were compared with those from broth microdilution (the reference method), and agreement was assessed based on MICs and Clinical Laboratory Standards Institute (CLSI) interpretative criteria using 2010 susceptibility breakpoints. Based on broth microdilution, 0%, 2.2%, and 97.8% of the KPC isolates were classified as susceptible, intermediate, and resistant to meropenem, respectively. Results from MicroScan demonstrated the most agreement with those from broth microdilution, with 95.6% agreement based on the MIC and 2.2% classified as minor errors, and no major or very major errors. Etest demonstrated 82.6% agreement with broth microdilution MICs, a very major error rate of 2.2%, and a minor error rate of 2.2%. Vitek 2 MIC agreement was 30.4%, with a 23.9% very major error rate and a 39.1% minor error rate. Sensititre demonstrated MIC agreement for 26.1% of isolates, with a 3% very major error rate and a 26.1% minor error rate. Application of FDA breakpoints had little effect on minor error rates but increased very major error rates to 58.7% for Vitek 2 and Sensititre. Meropenem MIC results and categorical interpretations for carbapenemase-producing K. pneumoniae differ by methodology. Confirmation of testing results is encouraged when an accurate MIC is required for antibiotic dosing optimization.

Rhizomucor variabilis var. regularior and Hormographiella aspergillata infections in a leukemic bone marrow transplant recipient with refractory neutropenia.

Rhizomucor variabilis and Hormographiella aspergillata rarely cause human infections. This report details a fatal case of a 14-year-old female with leukemia posthematopoietic cell transplant and relapse with refractory pancytopenia. The patient first developed an R. variabilis var. regularior palate infection and later developed a cutaneous H. aspergillata infection while on posaconazole and caspofungin therapy.

Use of cefepime for the treatment of infections caused by extended spectrum beta-lactamase-producing Klebsiella pneumoniae and Escherichia coli.

An investigation to determine the efficacy of cefepime in treating infections caused by extended spectrum beta-lactamase (ESBL)-producing strains of Klebsiella pneumonia and Escherichia coli was performed. Retrospective chart reviews were conducted on patients who received cefepime and had an ESBL-producing E. coli or K. pneumoniae isolated from a clinical specimen. Among 13 patients with 15 episodes and 17 sites of infection, there were 12 episodic clinical cures, 1 clinical improvement, and 2 failures. Bacteriologic eradication of the infecting organism from the original clinical site was seen in 11 of the episodes with an additional presumed eradication. Cefepime is a potential alternative, in many cases, to the carbapenems for the treatment of infections caused by ESBL-producing bacteria.

Lactobacillus acidophilus bacteraemia after use of a probiotic in a patient with AIDS and Hodgkin's disease.

We report the case of a patient who developed bacteraemia and septic pulmonary emboli with Lactobacillus acidophilus after taking a probiotic containing this organism.

Asymptomatic rectal colonization with carbapenem-resistant Enterobacteriaceae and Clostridium difficile among residents of a long-term care facility in New York City.

BACKGROUND: Residents of long-term care facilities (LTCFs) are at increased risk for colonization and development of infections with multidrug-resistant organisms. This study was undertaken to determine prevalence of asymptomatic rectal colonization with Clostridium difficile (and proportion of 027/NAP1/BI ribotype) or carbapenem-resistant Enterobacteriaceae (CRE) in an LTCF population. METHODS: Active surveillance was performed for C difficile and CRE rectal colonization of 301 residents in a 320-bed (80-bed ventilator unit), hospital-affiliated LTCF with retrospective chart review for patient demographics and potential risk factors. RESULTS: Over 40% of patients had airway ventilation and received enteral feeding. One-third of these patients had prior C difficile-associated infection (CDI). Asymptomatic rectal colonization with C difficile occurred in 58 patients (19.3%, one-half with NAP1+), CRE occurred in 57 patients (18.9%), and both occurred in 17 patients (5.7%). Recent CDI was significantly associated with increased risk of C difficile ± CRE colonization. Multivariate logistic regression analysis revealed presence of tracheostomy collar to be significant for C difficile colonization, mechanical ventilation to be significant for CRE colonization, and prior CDI to be significant for both C difficile and CRE colonization. CONCLUSIONS: The strong association of C difficile or CRE colonization with disruption of normal flora by mechanical ventilation, enteral feeds, and prior CDI carries important implications for infection control intervention in this population.

Pseudo-outbreak of Mycobacterium fortuitum due to contaminated ice machines.

BACKGROUND: An almost 4-fold increase from normal baseline levels in the isolation of Mycobacterium fortuitum from respiratory tract specimens was observed. The majority of these isolates were obtained from patients residing on 1 of 2 wards, prompting an epidemiologic investigation. METHODS: In addition to patient specimens, environmental cultures were collected from various water sources on the 2 affected wards. Samples were also collected from uninvolved areas of the hospital. All specimens were cultured with use of a continuously monitored broth system for the isolation of mycobacteria. RESULTS: The respiratory tracts of 19 patients were colonized by M fortuitum. Surveillance cultures obtained from uninvolved areas of the hospital were either negative for mycobacteria or were colonized by M avium complex or M gordonae. Two ice machines, servicing the affected areas each, were colonized by M fortuitum in multiple cultures. CONCLUSIONS: The M fortuitum pseudo-outbreak was due to contaminated ice machines located on each of the affected units. After removal and replacement of the ice machines, the pseudo-outbreak resolved.

Active surveillance for carbapenem-resistant Enterobacteriaceae using stool specimens submitted for testing for Clostridium difficile.

Active surveillance to identify asymptomatic carriers of carbapenem-resistant Enterobacteriaceae (CRE) is a recommended strategy for CRE control in healthcare facilities. Active surveillance using stool specimens tested for Clostridium difficile is a relatively low-cost strategy to detect CRE carriers. Further evaluation of this and other risk factor-based active surveillance strategies is warranted.

Prevalence and risk factors for acquisition of carbapenem-resistant Enterobacteriaceae in the setting of endemicity.

OBJECTIVE: To describe the epidemiology of carbapenem-resistant Enterobacteriaceae (CRE) carriage and acquisition among hospitalized patients in an area of CRE endemicity. DESIGN: Cohort study with a nested case-control study. SETTING: Two acute care, academic hospitals in New York City. PARTICIPANTS: All patients admitted to 7 study units, including intensive care, medical-surgical, and acute rehabilitation units. METHOD: Perianal samples were collected from patients at admission and weekly thereafter to detect asymptomatic gastrointestinal carriage of CRE. A nested case-control study was performed to identify factors associated with CRE acquisition. Case patients were those who acquired CRE during a single hospitalization. Control subjects had no microbiologic evidence of CRE and at least 1 negative surveillance sample. Clinical data were abstracted from the medical record. RESULTS: The prevalence of CRE in the study population was 5.4% (306 of 5,676 patients), and 104 patients met the case definition of acquisition during a single hospital stay. Mechanical ventilation (odds ratio [OR], 11.5), pulmonary disease (OR, 5.2), days of antibiotic therapy (OR, 1.04), and CRE colonization pressure (OR, 1.15) were independently associated with CRE acquisition. Pulsed-field gel electrophoresis analysis identified 87% of tested Klebsiella pneumoniae isolates as sharing related patterns (greater than 78% similarity), which suggests clonal transmission within and between the study hospitals. CONCLUSIONS: Critical illness and underlying medical conditions, CRE colonization pressure, and antimicrobial exposure are important risk factors for CRE acquisition. Adherence to infection control practices and antimicrobial stewardship appear to be critical components of a CRE control program.

No consistent relationship of glioblastoma incidence and cytomegalovirus seropositivity in whites, blacks, and Hispanics.

UNLABELLED: Glioblastoma multiforme is the most common and most aggressive type of primary brain tumor, accounting for 52% of all primary brain tumor cases and 20% of all intracranial tumors. Recently, evidence for a viral cause has been postulated, possibly cytomegalovirus (CMV). In one report, 80% of patients with newly diagnosed glioblastoma multiforme had detectable cytomegalovirus DNA in their peripheral blood, while sero-positive normal donors and other surgical patients did not exhibit detectable virus. However, another study reported that five glioblastoma patients showed no circulating CMV detected either with RT-PCR or blood culture. MATERIALS AND METHODS: We utilized Cytomegalovirus Seroprevalence in the United States data from the National Health and Nutrition Examination Surveys, 1988-2004. Glioblastoma Incidence Rates 2004-2008 by race and gender are from Cancer of the Brain and Other Nervous System - SEER Stat Fact Sheets (http://seer.cancer.gov/statfacts/html/brain.html). Statistical significance was determined from published 95% confidence intervals. RESULTS: CMV seroprevalence rates are not consistently related to glioblastoma incidence rates. CMV seroprevalence is significantly lower in whites than in blacks or Hispanics (Mexican Americans), while glioblastoma incidence is higher. However, both CMV seroprevalence and glioblastoma incidence are higher in Hispanics than in blacks. CMV seroprevalence rates are significantly higher in women, 55.5% (53.3-57.7, mean ± 95% CI) than men, 45.2% (42.4-48.0), although glioblastoma is more common in men. CONCLUSION: A possible CMV-glioblastoma association cannot be readily substantiated with CMV seropositivity rates.

No circulating cytomegalovirus in five patients with glioblastoma multiforme.

BACKGROUND: Glioblastoma multiforme is the most common and most aggressive type of primary brain tumor, accounting for 52% of all primary brain tumor cases and 20% of all intracranial tumors. Recently, evidence for a viral cause has been postulated, possibly SV40 or more likely cytomegalovirus (CMV). One report indicated that 80% of patients with newly diagnosed glioblastoma multiforme have detectable cytomegalovirus DNA in their peripheral blood, while sero-positive normal donors and other surgical patients did not exhibit detectable virus. PATIENTS AND METHODS: In the current study, we examined peripheral blood of 5 patients with newly diagnosed glioblastoma multiforme. Peripheral blood was collected in anticoagulated tubes from five patients with newly diagnosed glioblastoma multiforme referred for radiation therapy. We used standard methods for detecting CMV by reverse transcriptase-polymerase chain reaction (RT-PCR) and peripheral blood culture. RESULTS: None of our patients had circulating CMV. CONCLUSION: There are four subtypes of glioblastoma. We hypothesize that circulating CMV might be limited to some, but not all of these subtypes, and that our failure to detect CMV might be attributed to the fact that none of these patients had the appropriate subtype or subtypes.

Mycobacterium avium complex infection in a neck abscess: a diagnostic pitfall in fine-needle aspiration biopsy of head and neck lesions.

Fine-needle aspiration biopsy (FNAB) is a useful tool in the diagnosis of mycobacterial disease, especially Mycobacterium tuberculosis. However, nontuberculous mycobacterial infection diagnosed with FNAB material is much rarer, with Mycobacterium avium complex being the most common. In this report, we present the case of a 21-year-old HIV positive man, who presented with a unilateral, tender, enlarging cervical neck mass. FNAB had revealed acute inflammation. Mycobacterium avium complex grew in culture from the material that was aspirated and was confirmed by DNA probe. Because of the paucity of articles on this subject in the cytology literature, it is important to reiterate the value of the material aspirated at the bedside and the clinic in the diagnosis of infectious disease. When faced with antibiotic-resistant cellulitis and abscesses, the FNAB material must be sent for acid fast bacteria smears and culture.