Multicenter evaluation of the LightCycler methicillin-resistant Staphylococcus aureus (MRSA) advanced test as a rapid method for detection of MRSA in nasal surveillance swabs.

The rate of methicillin-resistant Staphylococcus aureus (MRSA) infection continues to rise in many health care settings. Rapid detection of MRSA colonization followed by appropriate isolation can reduce transmission and infection. We compared the performance of the new Roche LightCycler MRSA advanced test to that of the BD GeneOhm MRSA test and culture. Double-headed swabs were used to collect anterior nasal specimens from each subject. For both tests, DNA was extracted and real-time PCR was performed according to manufacturer's instructions. For culture, one swab of the pair was plated directly to CHROMagar MRSA. The swab paired with the BD GeneOhm MRSA test was also placed into an enrichment broth and then plated to CHROMagar MRSA. Colonies resembling staphylococci were confirmed as S. aureus by standard methods. Discrepant specimens had further testing with additional attempts to grow MRSA as well as sample amplicon sequencing. Agreement between results for the two swabs was 99.3% for those with valid results. A total of 1,402 specimens were tested using direct culture detection of MRSA as the gold standard; 187 were culture positive for MRSA. The LightCycler MRSA advanced test had relative sensitivity and specificity of 95.2% (95% confidence interval [CI]: 91.1% to 97.8%) and 96.4% (95% CI: 95.2% to 97.4%), respectively. The BD GeneOhm assay had relative sensitivity and specificity of 95.7% (95% CI: 91.7% to 98.1%) and 91.7% (95% CI: 90.0% to 93.2%), respectively. Following discrepancy analysis, the relative sensitivities of the LightCycler MRSA advanced test and the BD GeneOhm MRSA assay were 92.2 and 93.2%, respectively; relative specificities were 98.9 and 94.2%, respectively. Specificity was significantly better (P<0.001) with the LightCycler MRSA advanced test. The sensitivity of direct culture was 80.4%. The LightCycler MRSA advanced test is a useful tool for sensitive and rapid detection of MRSA nasal colonization.

Quantitation of Staphylococcus aureus in seawater using CHROMagar SA.

A microbiological algorithm has been developed to analyze beach water samples for the determination of viable colony forming units (CFU) of Staphylococcus aureus (S. aureus). Membrane filtration enumeration of S. aureus from recreational beach waters using the chromogenic media CHROMagar SA alone yields a positive predictive value (PPV) of 70%. Presumptive CHROMagar SA colonies were confirmed as S. aureus by 24-hour tube coagulase test. Combined, these two tests yield a PPV of 100%. This algorithm enables accurate quantitation of S. aureus in seawater in 72 hours and could support risk-prediction processes for recreational waters. A more rapid protocol, utilizing a 4-hour tube coagulase confirmatory test, enables a 48-hour turnaround time with a modest false negative rate of less than 10%.

A six-year descriptive study of hospital-associated infection in trauma patients: demographics, injury features, and infection patterns.

BACKGROUND AND PURPOSE: Hospital-associated infection (HAI) is of concern to surgeons providing care for traumatized patients, as such patients have a higher rate of infection than other patients. Infection surveillance programs often study trauma patients within other populations (e.g., intensive care unit [ICU], surgery), and important issues may be missed. Information identifying trauma patients at risk, most frequent infection sites, and pathogens is of importance for surveillance and infection control. Measurement is essential to improving care. METHODS: We evaluated the HAI rate, demographics, injury characteristics, and HAI patterns (microorganisms, sites, antibiotics) in trauma patients (1996-2001). We used two-tailed Mann-Whitney and Fisher exact tests for univariate analysis and a stepwise multivariable logistic regression model for association of multiple variables with the development of HAI. RESULTS: The incidence of HAI was 501 (9.1%) in 5,537 patients. Trauma patients with HAI were older (p < 0.001), more severely injured (p < 0.001), and more likely to have multi-system trauma (p = 0.027). Development of HAI was associated with all injury sites except the face. The most common pathogens were gram-positive cocci, and the most common infection sites were urinary and respiratory, with 157 of 501 (31%) being ventilator-associated pneumonia. The antibiotics most commonly used were cephalosporins and fluoroquinolones. Of 5,537 trauma patients, 19 (0.3%) had Staphylococcus aureus resistant to methicillin, which was higher (p < 0.001) than in the non-trauma patients (176 in 146,727 [0.1%]). CONCLUSIONS: Hospital-associated infections occur frequently in trauma patients. This paper identifies populations to target for surveillance and HAI control initiatives. With increased interest in adverse event prevention and continuing quality of care improvement, these data provide a benchmark for this institution and others.

Streptococcus pneumoniae serotypes in Utah adults at the end of the PCV7 era.

While heptavalent pneumococcal conjugate vaccine (PCV) has decreased vaccine type invasive pneumococcal disease (IPD) nationwide, rapid serotype replacement and increasing parapneumonic empyema, has been reported in Utah children. The effect of pediatric vaccination on adults in this population is unknown. We identified 117 adults with IPD from the Intermountain Healthcare Central Laboratory between November 2009 and October 2010. We serotyped 61 (52%) stored isolates. We compared the serotype distribution of adult IPD isolates with that of pediatric isolates collected in 2009-2010. PCV7 serotypes were rare in adults (3%) and children (3%). Emerging 13-valent PCV serotypes 3, 7F, and 19A caused the majority of IPD in adults (63%) and children (56%). Fifty-one (84%) adult isolates were serotypes included in 23-valent polysaccharide vaccine and 66% in PCV13. Adult and pediatric IPD serotypes are closely associated in Utah. PCV13 vaccination in Utah children is likely to significantly impact IPD in Utah adults.

Tuberculosis in a solid-organ transplant recipient: modern-day implications.

The clinical presentation and disease course of tuberculosis (TB) in a solid-organ transplant (SOT) recipient may be atypical and the risk of mortality is high. Herein we examine the role of the different tests used in diagnosis of TB and review the specifics of anti-mycobacterial therapy and the public health implications of TB in a SOT recipient.

Adverse drug events in trauma patients.

BACKGROUND: Adverse drug events (ADEs) are noxious and unintended results of drug therapy. ADEs have been shown to be a risk to hospitalized patients. The purpose of this study was to determine the rate and nature of ADEs in trauma patients and to characterize the population at risk. METHODS: An electronic medical record, a hospital wide computerized surveillance program, and a clinical pharmacist prospectively investigated ADEs in 4,320 trauma patients from 1996 through 1999. RESULTS: The rate of ADEs in trauma patients (98/4320, 2.3%) was twice that of non-trauma hospital patients (1,111/96,218, 1.2%, p < 0.001). Traumatized females had ADEs 1.5 times more often than traumatized males (2.7% versus 1.8%, p = 0.052). The medication class most often associated with ADEs was analgesics with 54% involving morphine and 20% involving meperidine. The most common ADEs were nausea, vomiting, and itching. Only one ADE was directly attributed to a medical error. CONCLUSIONS: Trauma patients are at double the risk for ADEs. Analgesics are particularly associated with ADEs and use should be carefully monitored.

Immunity to malaria after administration of ultra-low doses of red cells infected with Plasmodium falciparum.

BACKGROUND: The ability of T cells, acting independently of antibodies, to control malaria parasite growth in people has not been defined. If such was shown to be effective, an additional vaccine strategy could be pursued. Our aim was to ascertain whether or not development of cell-mediated immunity to Plasmodium falciparum blood-stage infection could be induced in human beings by exposure to malaria parasites in very low density. METHODS: We enrolled five volunteers from the staff at our research institute who had never had malaria. We used a cryopreserved inoculum of red cells infected with P falciparum strain 3D7 to give them repeated subclinical infections of malaria that we then cured early with drugs, to induce cell-mediated immune responses. We tested for development of immunity by measurement of parasite concentrations in the blood of volunteers by PCR of the multicopy gene STEVOR and by following up the volunteers clinically, and by measuring antibody and cellular immune responses to the parasite. FINDINGS: After challenge and a extended period without drug cure, volunteers were protected against malaria as indicated by absence of parasites or parasite DNA in the blood, and absence of clinical symptoms. Immunity was characterised by absence of detectable antibodies that bind the parasite or infected red cells, but by the presence of a proliferative T-cell response, involving CD4+ and CD8+ T cells, a cytokine response, consisting of interferon gamma but not interleukin 4 or interleukin 10, induction of high concentrations of nitric oxide synthase activity in peripheral blood mononuclear cells, and a drop in the number of peripheral natural killer T cells. INTERPRETATION: People can be protected against the erythrocytic stage of malaria by a strong cell-mediated immune response, in the absence of detectable parasite-specific antibodies, suggesting an additional strategy for development of a malaria vaccine