Use of Rapid Molecular Polymerase Chain Reaction in Early Detection of Bacteremia in Neonates Prior to Blood Culture Positivity: A Pilot Study.

OBJECTIVE: There has been national strive to decrease the time needed to identify microorganisms in blood culture samples to reduce antibiotic use. This study evaluated rapid molecular polymerase chain reaction (PCR) use in identifying microorganisms in negative culture bottles from neonates with suspected bacterial blood stream infection at 20 to 24 hours of incubation. STUDY DESIGN: All blood specimens from neonates with suspected blood stream infection were included. Specimens were incubated using a standard blood culturing instrument that would flag positive if bacterial growth was detected. If the specimen was flagged positive at <20 hours, it was tested by PCR and plated for identification as per standard protocol. In our design, if specimen was not flagged at 20 hours of incubation, the bottle was sterilely accessed and a sample was obtained for PCR testing. The bottle would be returned for incubation for 120 hours or until flagged positive. RESULTS: A total of 192 blood specimens were included. Four specimens flagged positive at <20 hours and were all found to be positive by PCR. All other samples did not flag positive by 20 hours of incubation and were tested by PCR between 20 and 24 hours. One sample tested positive via PCR at 21.6 hours then flagged positive on the culturing instrument at 23.5 hours. All other specimens were negative by PCR and remained culture negative at 120 hours. The positive and negative predictive value of PCR verified by blood culture were both equal to 1.0. CONCLUSION: Using rapid molecular PCR on blood culture specimens at 20 to 24 hours of incubation provides 100% true negative results possibly allowing providers to discontinue antibiotics at 24 hours. KEY POINTS: · Antibiotic overuse leads to adverse neonatal outcomes.. · Molecular PCR may have true negative results.. · Larger study is needed to discontinue antibiotics earlier..

Characteristics and Severity of Disease among 100 Cases of Imported Malaria Seen at a U.S. University Hospital, 2000-2017.

Malaria acquired in endemic areas poses a substantial risk to travelers arriving in or returning to the United States. Timely diagnosis and recognition of severe illness are crucial; however, many U.S.-based clinicians lack familiarity with this disease. We conducted a retrospective review of 100 cases of malaria in adults seen at a single urban university hospital during 2000-2017. Descriptive and analytical statistics were calculated, including logistic regression modeling case severity. Most of the patients presented with Plasmodium falciparum (76%), most commonly after travel from sub-Saharan Africa (94%). Prior malaria experience was common (50%), but adherence to a prophylactic regimen was exceedingly rare (4%). Twenty-one patients had severe malaria, including 10 with cerebral malaria. Severity was predicted by high parasitemia, bandemia, hypoglycemia, and hypotension at the time of presentation. In 24 patients, the initial treatment regimen was changed, usually because of the appearance of clinical deterioration or drug toxicity. One patient required intravenous artesunate. All patients survived, although one suffered fetal loss. Among 30 patients initially evaluated at other institutions, 43% had been treated for an alternative diagnosis. The most common reasons for transfer of patients to our hospital were inadequate facilities and lack of expertise with malaria. There needs to be increased awareness among U.S.-based travelers and clinicians regarding malaria as a potentially lethal condition, emphasizing the use of appropriate prophylaxis. Our simple model of disease severity could serve frontline physicians when deciding which patients should be admitted to the intensive care unit or transferred for higher level care.

A cost-effective interdisciplinary approach to microbiologic send-out test use.

CONTEXT: Use of reference laboratories for selected laboratory testing (send-out tests) represents a significant source of laboratory costs. As the use of more complex molecular analyses becomes common in the United States, strategies to reduce costs in the clinical laboratory must evolve in order to provide high-value, cost-effective medicine. OBJECTIVE: To report a strategy that employs clinical pathology house staff and key hospital clinicians in the effective use of microbiologic send-out testing. DESIGN: The George Washington University Hospital is a 370-bed academic hospital in Washington, DC. In 2012 all requisitions for microbiologic send-out tests were screened by the clinical pathology house staff prior to final dispensation. Tests with questionable utility were brought to the attention of ordering clinicians through the use of interdisciplinary rounds and direct face-to-face consultation. RESULTS: Screening resulted in a cancellation rate of 38% of send-out tests, with proportional cost savings. Nucleic acid tests represented most of the tests screened and the largest percentage of cost saved through screening. Following consultation, requested send-out tests were most often canceled because of a lack of clinical indication. CONCLUSIONS: Direct face-to-face consultation with ordering physicians is an effective, interdisciplinary approach to managing the use of send-out testing in the microbiology laboratory.

Single-molecule long-read 16S sequencing to characterize the lung microbiome from mechanically ventilated patients with suspected pneumonia.

In critically ill patients, the development of pneumonia results in significant morbidity and mortality and additional health care costs. The accurate and rapid identification of the microbial pathogens in patients with pulmonary infections might lead to targeted antimicrobial therapy with potentially fewer adverse effects and lower costs. Major advances in next-generation sequencing (NGS) allow culture-independent identification of pathogens. The present study used NGS of essentially full-length PCR-amplified 16S ribosomal DNA from the bronchial aspirates of intubated patients with suspected pneumonia. The results from 61 patients demonstrated that sufficient DNA was obtained from 72% of samples, 44% of which (27 samples) yielded PCR amplimers suitable for NGS. Out of the 27 sequenced samples, only 20 had bacterial culture growth, while the microbiological and NGS identification of bacteria coincided in 17 (85%) of these samples. Despite the lack of bacterial growth in 7 samples that yielded amplimers and were sequenced, the NGS identified a number of bacterial species in these samples. Overall, a significant diversity of bacterial species was identified from the same genus as the predominant cultured pathogens. The numbers of NGS-identifiable bacterial genera were consistently higher than identified by standard microbiological methods. As technical advances reduce the processing and sequencing times, NGS-based methods will ultimately be able to provide clinicians with rapid, precise, culture-independent identification of bacterial, fungal, and viral pathogens and their antimicrobial sensitivity profiles.

Induction of MRSA Biofilm by Low-Dose ß-Lactam Antibiotics: Specificity, Prevalence and Dose-Response Effects.

Methicillin-resistant Staphylococcus aureus (MRSA) is a leading cause of hospital- and community-associated infections. The formation of adherent clusters of cells known as biofilms is an important virulence factor in MRSA pathogenesis. Previous studies showed that subminimal inhibitory (sub-MIC) concentrations of methicillin induce biofilm formation in the community-associated MRSA strain LAC. In this study we measured the ability sub-MIC concentrations of eight other ß-lactam antibiotics and six non-ß-lactam antibiotics to induce LAC biofilm. All eight ß-lactam antibiotics, but none of the non-ß-lactam antibiotics, induced LAC biofilm. The dose-response effects of the eight ß-lactam antibiotics on LAC biofilm varied from biphasic and bimodal to near-linear. We also found that sub-MIC methicillin induced biofilm in 33 out of 39 additional MRSA clinical isolates, which also exhibited biphasic, bimodal and linear dose-response curves. The amount of biofilm formation induced by sub-MIC methicillin was inversely proportional to the susceptibility of each strain to methicillin. Our results demonstrate that induction of biofilm by sub-MIC antibiotics is a common phenotype among MRSA clinical strains and is specific for ß-lactam antibiotics. These findings may have relevance to the use of ß-lactam antibiotics in clinical and agricultural settings.

Nasal colonization among premature infants treated with nasal continuous positive airway pressure.

We examined the relationship between the use of nasal continuous positive airway pressure (CPAP) and nasal colonization among low-birth-weight (LBW) infants. We prospectively cultured the nares of LBW infants on admission and weekly until hospital discharge. The modality of respiratory support during each culture was recorded. Bivariate and multivariate analyses were conducted to test the relationship between CPAP and nasal colonization. Analyses were repeated after stratifying infants into three birth-weight categories: 1500 to 2499 g, 1000 to 1499 g, and < 1000 g. In total, 766 nasal cultures were obtained from 167 infants. Nasal colonization with gram-negative bacilli was increased with the use of CPAP in all birth-weight categories ( P < 0.05) and with vaginal delivery in infants weighing < 1000 g and 1500 to 2499 g ( P = 0.04 and P = 0.02, respectively). Nasal colonization with any potential pathogen increased with the use of CPAP in all birth-weight categories ( P < 0.001), with the presence of chorioamnionitis in infants < 1000 g ( P = 0.055) and at younger gestational age in infants 1000 to 1499 g ( P = 0.0026). Caucasian infants 1500 to 2499 g had less colonization than infants of other races ( P = 0.01). Nasal CPAP is associated with increased colonization with gram-negative bacilli.

PREFABRICATION DESIGN CONSIDERATIONS FOR A LONG-TERM ELECTRICALLY-ACTUATED ABDOMINAL LEFT VENTRICULAR ASSIST DEVICE (E-TYPE ALVAD).

The conceptual design and development of a long-term, low-profile intracorporeal left ventricular assist device is a multifaceted project involving a series of technical, anatomic and physiologic considerations. Patients with severe left ventricular failure refractory to all other forms of therapy could benefit from such a device. Prior to fabrication of such a blood pump, consideration must be given to physiologic parameters of the projected patient population. The pump must be designed to meet physiologic demands and yet conform to the anatomic constraints posed by the patient population. We measured the body surface area (BSA) of a group of patients (n=50) and found the mean BSA for this group to be 1.804 +/- 0.161 m(2). Using 25 ml/m(2) as a stroke volume index indicative of left ventricular failure and a stroke volume index of 45 ml/m(2) as normal, distributions of stroke volumes (normal and in left ventricular failure) were plotted for a potential population and demonstrated that 63% of the projected population can be returned to normal by a pump with a stroke volume >/= 83 ml. Cadaver fitting studies established that 73% of the potential population can accommodate an ALVAD 10.8 cm in diameter. In-vitro tests demonstrated that a pump stroke volume >/= 83 ml could be achieved by the proposed pump with a 15 mmHg filling pressure at rates up to 125 B/min. A pusher-plate stroke of 0.56 inches would be necessary to provide a stroke volume >/= 83 ml. The percent of the patient population that could be served was determined by excluding those in whom the pump would not fit or in whom it would provide less than a normal resting stroke volume. Approximately 73% of the projected patient population would accommodate this pump and be returned to normal circulatory dynamics.