Deposition of Bacteria and Bacterial Spores by Bathroom Hot-Air Hand Dryers.

Hot-air hand dryers in multiple men's and women's bathrooms in three basic science research areas in an academic health center were screened for their deposition on plates of (i) total bacteria, some of which were identified, and (ii) a kanamycin-resistant Bacillus subtilis strain, PS533, spores of which are produced in large amounts in one basic science research laboratory. Plates exposed to hand dryer air for 30 s averaged 18 to 60 colonies/plate; but interior hand dryer nozzle surfaces had minimal bacterial levels, plates exposed to bathroom air for 2 min with hand dryers off averaged ≤1 colony, and plates exposed to bathroom air moved by a small fan for 20 min had averages of 15 and 12 colonies/plate in two buildings tested. Retrofitting hand dryers with HEPA filters reduced bacterial deposition by hand dryers ∼4-fold, and potential human pathogens were recovered from plates exposed to hand dryer air whether or not a HEPA filter was present and from bathroom air moved by a small fan. Spore-forming colonies, identified as B. subtilis PS533, averaged ∼2.5 to 5% of bacteria deposited by hand dryers throughout the basic research areas examined regardless of distance from the spore-forming laboratory, and these were almost certainly deposited as spores. Comparable results were obtained when bathroom air was sampled for spores. These results indicate that many kinds of bacteria, including potential pathogens and spores, can be deposited on hands exposed to bathroom hand dryers and that spores could be dispersed throughout buildings and deposited on hands by hand dryers.IMPORTANCE While there is evidence that bathroom hand dryers can disperse bacteria from hands or deposit bacteria on surfaces, including recently washed hands, there is less information on (i) the organisms dispersed by hand dryers, (ii) whether hand dryers provide a reservoir of bacteria or simply blow large amounts of bacterially contaminated air, and (iii) whether bacterial spores are deposited on surfaces by hand dryers. Consequently, this study has implications for the control of opportunistic bacterial pathogens and spores in public environments including health care settings. Within a large building, potentially pathogenic bacteria, including bacterial spores, may travel between rooms, and subsequent bacterial/spore deposition by hand dryers is a possible mechanism for spread of infectious bacteria, including spores of potential pathogens if present.

Effects of Clinically Meaningful Concentrations of Antipseudomonal ß-Lactams on Time to Detection and Organism Growth in Blood Culture Bottles.

The effectiveness of antimicrobial binding resins present in blood culture (BC) bottles in removing meropenem, ceftolozane-tazobactam, and ceftazidime-avibactam is unknown. We assessed the time to detection (TTD) and growth of 2 Pseudomonas aeruginosa isolates in the presence of clinically meaningful concentrations of these antibiotics. Bactec Plus Aerobic/F and BacT/Alert FA Plus BC bottles were inoculated with one of two isolates (1 meropenem susceptible and 1 resistant), followed by fresh whole blood containing the peak, midpoint, or trough plasma concentrations for meropenem, ceftolozane-tazobactam, and ceftazidime-avibactam. Matching bottles were loaded into their respective detection instruments and a standard incubator at 37°C, with TTD and CFU being monitored for up to 72 h. Bacterial growth was observed for 11/48 (22.9%), 22/48 (45.8%), and 47/48 (97.9%) of all BC bottles inoculated with the peak, midpoint, and trough concentrations, respectively (P ≤ 0.001). When P. aeruginosa was isolated, the TTD was typically <26 h, and no differences between Bactec and BacT/Alert bottles were observed. In both systems, meropenem was removed to a greater degree than were ceftolozane and ceftazidime; however, concentrations for all antibiotics remained above the MIC for the susceptible organisms at 12 h. BC bottles containing antibiotic binding resins may not sufficiently inactivate achievable concentrations of meropenem, ceftolozane-tazobactam, and ceftazidime-avibactam. The consistent identification of both P. aeruginosa isolates was observed only in the presence of antibiotic trough concentrations. To minimize false-negative BC results for patients already receiving these antibiotics, cultures should be collected just prior to the next dose, when antibiotic concentrations are lowest.

Antibiotic Utilization and Opportunities for Stewardship Among Hospitalized Patients With Influenza Respiratory Tract Infection.

OBJECTIVE: Hospitalized influenza patients are often treated with antibiotics empirically while awaiting final diagnosis. The goal of this study was to describe the inappropriate continuation of antibiotics for influenza respiratory tract infections (RTIs). DESIGN: We retrospectively studied adults admitted to our institution over 2 respiratory flu seasons with positive influenza RTIs. Inappropriate antibiotic duration (IAD) was defined as antibiotic use for >24 hours after a positive influenza test in patients presenting with <72 hours of RTI symptoms and with no other indications of bacterial infection. RESULTS: During the study period, 322 patients included in this study were admitted for influenza RTI. Respiratory cultures were ordered for 50 of these patients (15.5%) and 71 patients (22%) had a positive chest x-ray, but antibiotics were prescribed to 211 patients (65.5%) on admission. Antibiotics were inappropriately continued in 73 patients (34.5%). Patients receiving IAD had a longer length of stay (LOS) (median, 6 days; range, 4-9 days) compared with those whose antibiotics were discontinued appropriately (median, 5 days; range, 3-8 days) and those who were not treated with antibiotics (median, 4 days; range, 3-6 days; P<.001). However, mortality was similar among these 3 groups: 3 patients (4.1%) from the IAD cohort died; 6 patients (4.3%) from the group with an appropriate antibiotic duration died; and 2 patients [1.8%] from the group given no antibiotics died (P=.510). The 30-day readmission rates were similar as well: 9 patients (12.3%) from the IAD group were readmitted within 30 days; 21 patients (15.2%) from the group with appropriate antibiotic duration were readmitted; and 11 patients (9.9%) from the group given no antibiotics were readmitted (P=.455). Total hospital costs were greater in patients treated with IAD ($10,645; range, $6,485-$18,035) compared with the group treated with appropriate antibiotic duration ($7,479; range, $4,866-$12,922) and the group given no antibiotics $5,961 (range, $4,711-$9,575). Thus, the hospital experienced a median loss in net hospital revenue of $2,076 per IAD patient compared with a patient for which antibiotic duration was appropriate. CONCLUSION: The majority of patients with influenza RTI received antibiotics on admission, and 34.5% were inappropriately continued on antibiotics without evidence of bacterial infection, which led to increased LOS, loss of net revenue, and no improvement in outcome. Thus, stewardship initiatives aimed at this population are warranted.

Cokeromyces recurvatus identified in lung biopsy: case report of a non-pathogenic fungus, highlighting its potential histologic mimics.

We report a case of aspiration in a patient with gastric outlet obstruction due to pancreatic adenocarcinoma, in which three large yeasts were identified on tissue biopsy of the lung infiltrate. The histologic sections of the yeasts showed densely eosinophilic, round to oval, thick-walled structures with frayed borders and intra-cystic bluish inclusions. There was a background of mixed neutrophilic and eosinophilic infiltrate along with focal tissue necrosis. Our initial differential diagnoses included the usual large yeasts such as Cryptococcus, Coccidioides, and Blastomyces. Immunohistochemistry revealed reactivity to the Blastomyces antibody. Mycology studies eventually identified the organism as Cokeromyces recurvatus. Anti-fungal treatment was withheld with spontaneous resolution of the infiltrates. This case demonstrates the importance of using culture to speciate organisms identified on tissue, separating pathogens from non-pathogens and non-living artifacts in order for appropriate management.

Early antibiotic discontinuation in patients with clinically suspected ventilator-associated pneumonia and negative quantitative bronchoscopy cultures.

OBJECTIVES: Preliminary data suggest that antibiotic discontinuation in patients with negative quantitative bronchoscopy and symptom resolution will not increase mortality. Because our hospital algorithm for antibiotic discontinuation rules out ventilator-associated pneumonia in the setting of negative quantitative bronchoscopy cultures, we compared antibiotic utilization and mortality in empirically treated, culture-negative ventilator-associated pneumonia patients whose antibiotic discontinuation was early versus late. DESIGN: Retrospective, observational cohort study. SETTING: Eight hundred sixty-seven bed, tertiary care, teaching hospital in Hartford, CT. PATIENTS: Eighty-nine patients with clinically suspected ventilator-associated pneumonia and a negative (<10 colony forming units/mL) quantitative bronchoscopy culture between January 2009 and March 2012. Early discontinuation patients (n = 40) were defined as those who had all antibiotic therapy stopped within one day of final negative culture report, whereas late discontinuation patients (n = 49) had antibiotics stopped later than one day. MEASUREMENTS: Univariate analyses assessed mortality, antibiotic duration, and frequency of superinfections. Multivariate logistic regression was performed to assess the effect of early discontinuation on hospital mortality. RESULTS: Patients had a mean ± SD Acute Physiology and Chronic Health Evaluation II score of 26.0 ± 6.0. Mortality was not different between early discontinuation (25.0%) and late discontinuation (30.6%) patients (p = 0.642). Antibiotic duration (days) was also not different for patients who died vs. those who survived (Median [interquartile range]: 3 [1-7.5] vs. 3 [1.75-6.25], respectively, p = 0.87), and when controlling for baseline characteristics and symptom resolution, only Acute Physiology and Chronic Health Evaluation II score was associated with hospital mortality on multivariate analyses. There were fewer superinfections (22.5% vs. 42.9%, p = 0.008), respiratory superinfections (10.0% vs. 28.6%, p = 0.036), and multidrug resistant superinfections (7.5% vs. 35.7%, p = 0.003), in early discontinuation compared with late discontinuation patients. CONCLUSIONS: In this severely ill population with clinically suspected ventilator-associated pneumonia and negative quantitative bronchoalveolar lavage cultures, early discontinuation of antibiotics did not affect mortality and was associated with a lower frequency of MDR superinfections.

Comparison of GeneXpert PCR to BD GeneOhm for detecting C. difficile toxin gene in GDH positive toxin negative samples.

The need for rapid diagnosis of Clostridium difficile (C. difficile) associated infection in a clinical microbiology laboratory has provided the stimulus for new diagnostic tests and testing protocols. A two-test algorithm has been proposed using assays such as Quik Chek Complete, which detects both C. difficile glutamate dehydrogenase (GDH) and C. difficile toxins A and B, followed by reflex testing of samples having inconclusive results (GDH positive and toxin negative) with PCR for identification of toxin gene specific DNA. The goal of this study was to compare the outcome and efficiency of PCR assays, BD GeneOhm and GeneXpert, for detecting C. difficile toxin B gene in samples that have tested indeterminate for C. difficile by the Quik Chek Complete test. Over a three-month period, a total of 41 cases tested indeterminate by Quik Chek Complete test and were retested by the aforementioned PCR assays. Out of the 41 samples, 36 had matching results in both assays; 19 negative samples and 17 positive samples. In terms of efficiency, GeneXpert was user-friendly and had a turnaround time (TAT) of 45 minutes with two-minute specimen processing compared to BD GeneOhm which had a TAT of 75 to 90 minutes.

Correlation between vancomycin and daptomycin MIC values for methicillin-susceptible and methicillin-resistant Staphylococcus aureus by 3 testing methodologies.

We examined the potential correlation between vancomycin and daptomycin MIC for 298 Staphylococcus aureus by broth microdilution (BMD), Etest, and MicroScan(®). Etest and BMD identified a significant, albeit poor, correlation between MICs (ρ = 0.29, P < .01, and ρ = 0.15, P = .01, respectively), but no correlation (ρ = 0.08, P = .18) was observed with MicroScan.

Influence of automated screening and confirmation of extended-spectrum beta-lactamase-producing members of the Enterobacteriaceae on prescribing of antibiotics.

This study investigated the clinician response to the extended-spectrum beta-lactamase (ESBL) confirmation report generated by an automated detection system, MicroScan Walkaway. The study compared two cohorts (pre- and post-automated detection) of patients with an ESBL-producing Escherichia coli or Klebsiella species non-urinary infection over the period October 2001-December 2006. Acceptance of the report, as defined by the initiation of carbapenem therapy, was observed in 69.2% of the post-automated detection cohort (n=78) versus 20% in the pre-automated detection period (n=15) (P

Prospective evaluation of rapid antigen tests for diagnosis of respiratory syncytial virus and human metapneumovirus infections.

Respiratory syncytial virus (RSV) and human metapneumovirus (hMPV) are two important viral pathogens that cause respiratory tract infections in the pediatric population. The rapid detection of these agents allows the prompt isolation and treatment of infected patients. In the present prospective study, we evaluated the performances of four rapid antigen detection assays, including a rapid chromatographic immunoassay (CIA) for RSV (Directigen EZ RSV; Becton Dickinson, Sparks, MD), a direct fluorescent-antibody assay (DFA) for RSV (Bartels; Trinity Biotech, Carlsbad, CA), and two DFAs for hMPV manufactured by Diagnostic Hybrids Inc. (DHI; Athens, OH) and Imagen (Oxoid Ltd., Basingstoke, Hampshire, United Kingdom). The clinical specimens tested comprised 515 nasopharyngeal aspirates submitted to the Clinical Microbiology Laboratory at Hartford Hospital from 1 November 2006 to 21 April 2007. Compared to the results of real-time reverse transcription-PCR (RT-PCR), the CIA had a sensitivity of 79.8% and a specificity of 89.5%. The RSV DFA with Bartels reagents showed a sensitivity of 94.1% and a specificity of 96.8%. For hMPV, the sensitivity and specificity were 62.5% and 99.8%, respectively, for the DHI DFA and 63.2% and 100%, respectively, for the Imagen DFA. The hands-on and test turnaround times for CIA were 10 and 30 to 60 min, respectively, and the hands-on and test turnaround times for the RSV and hMPV DFAs were 30 and 105 min, respectively. We conclude that while the RSV CIA is user-friendly, it lacks sensitivity and specificity, especially during off-peak months. In contrast, the RSV DFA is more sensitive and specific, but interpretation of its results is subjective and it demands technical time and expertise. Similarly, both hMPV DFAs are highly specific in comparison to the results of RT-PCR, but their sensitivities await further improvements.

Confirmation of tick bite by detection of antibody to Ixodes calreticulin salivary protein.

Ticks introduce a variety of pharmacologically active molecules into their host during attachment and feeding in order to obtain a blood meal. People who are repeatedly exposed to ticks may develop an immune response to tick salivary proteins. Despite this response, people usually are unaware of having been bitten, especially if they are not repeatedly exposed to ticks. In order to develop a laboratory marker of tick exposure that would be useful in understanding the epidemiology of tick-borne infection and the immune response to tick bite, we developed an enzyme-linked immunosorbent assay (ELISA) to detect antibody to a recombinant form of calreticulin protein found in the salivary glands of Ixodes scapularis, a member of a complex of Ixodes ticks that serve as the vectors for Lyme disease, human babesiosis, and human granulocytic anaplasmosis. Using this assay, we tested sera obtained from C3H/HeN and BALB/c mice before and after experimental deer tick infestation. These mice developed antibody to Ixodes calreticulin antigen after infestation. We then used the same assay to test sera obtained from people before and after they experienced deer tick bite(s). People experiencing deer tick bite(s) developed Ixodes calreticulin-specific antibody responses that persisted for up to 17 months. This Ixodes recombinant calreticulin ELISA provides objective evidence of deer tick exposure in people.

Clinical correlation of the CLSI susceptibility breakpoint for piperacillin- tazobactam against extended-spectrum-beta-lactamase-producing Escherichia coli and Klebsiella species.

We assessed infections caused by extended-spectrum-beta-lactamase-producing Escherichia coli or Klebsiella spp. treated with piperacillin-tazobactam to determine if the susceptibility breakpoint predicts outcome. Treatment was successful in 10 of 11 nonurinary infections from susceptible strains and in 2 of 6 infections with MICs of >16/4 mug/ml. All six urinary infections responded to treatment regardless of susceptibility.

Case report and brief commentary: Wuchereria bancrofti and Onchocerca volvulus co-infection in a refugee from Sierra Leone.

Filarial infection is endemic in the tropics and is a public health problem in Africa, Asia, South and Central America, and the Pacific Islands. Co-infection with filarial nematodes, if unrecognized, can result in untoward therapeutic consequences. We report a case of co-infection of Wuchereria bancrofti and Onchocerca volvulus that was diagnosed by direct blood smear (W. bancrofti ) and serology (O. volvulus) in a native of Sierra Leone. We comment briefly on the therapeutic implications of the co-infection.

Preventing PCR amplification carryover contamination in a clinical laboratory.

During the past two decades PCR and several other DNA/RNA amplification techniques have become important diagnostic tools in clinical laboratories. Amplification products contamination has been the main impediment to using these techniques routinely in diagnostic laboratories. Over the years, several creative pre- and post-amplification methods have been developed that prevent amplicon carryover contamination. These procedures, coupled with automated systems that employ real-time amplification and simultaneous detection in a closed system, have substantially reduced the possibility of false positive results due to amplification products carryover contamination.

HIV resistance testing: an update.

In recent years, resistance testing has become an important tool in optimizing the combination therapy for treating HIV infected individuals. The identification of resistance mutations has allowed physicians to select the antiviral agents with maximum therapeutic benefic and minimum toxic side effects. The current therapeutic agents approved by the Food and Drug Administration (FDA), their mechanisms of actions, and the mutations of the HIV viral genome that lead to resistance to antiviral agents are discussed. In addition, methods of resistance testing, both genotypic and phenotypic, are evaluated with consideration of their inherent advantages and disadvantages.

Comparison of M4 and M4RT media for transporting cervical swab samples for PCR detection of Chlamydia trachomatis and Neisseria gonorrhoeae.

In a prospective study, M4RT medium was compared to the traditional M4 medium to transport cervical swab specimens for Neisseria gonorrhoeae/Chlamydia trachomatis (NG/CT) PCR testing using the Roche COBAS Amplicor. Two cervical swab samples were collected from 270 consecutive patients screened for NG/CT in a satellite facility. The swabs were placed individually in M4RT and M4 medium and were immediately refrigerated, transported to the laboratory on wet ice, and stored at 2 to 8 degrees C until the PCR testing was performed within 7 da of collection. Seven of the cervical swab samples transported in M4 or M4RT were PCR positive for CT. Two additional samples transported in M4RT and a third swab transported in M4 were CT PCR positive. These samples were PCR negative in the alternative medium. Similarly, 12 of the cervical swabs transported in M4 or M4RT were NG PCR positive. Three additional swabs transported in M4 media were NG PCR positive. Initially, 2 of these samples when transported in M4RT were NG PCR equivocal and were considered NG PCR positive on repeat testing. Similarly, 2 additional swab samples transported in M4 RT media were NG PCR positive. These samples, when transported in M4 media, were NG PCR equivocal or negative. However, on repeat testing the equivocal sample was considered NG PCR positive. We conclude M4 and M4RT transport media are equally reliable for transporting cervical swab samples for NG/CT PCR testing. M4RT medium is more convenient to use, as it did not require refrigeration until it was inoculated with the clinical sample.