Halomonas johnsoniae: review of a medically underappreciated genus of growing human importance.

The growing genus Halomonas includes bacteria favoring or tolerating high-saline/halide and high-pH environments. Infections are rarely reported. A patient developed Halomonas johnsoniae (previously reported only as dialysis unit environmental contaminants) bacteremia. The medical community is alerted to the pathogenic potential of the genus, particularly in a dialysis setting.

Ruling out bacteremia and bacterial meningitis in infants less than one month of age: is 48 hours of hospitalization necessary?

OBJECTIVE: The appropriate duration of hospitalization for infants ≤ 30 days admitted for fever or other concerns for a serious bacterial infection is an understudied area. We sought to determine the risk of a positive, pathogenic bacterial culture of blood or cerebrospinal fluid (CSF) in this population beyond 24 hours after collection. METHODS: This study was a retrospective review of 1145 infants aged ≤30 days who had a blood or CSF culture from 1999 to 2010 at Santa Clara Valley Medical Center, a county health system in San Jose, California. Time to notification and the probability of a positive culture result after 24 hours were calculated. Infants were considered high risk if they had either a white blood cell count <5000 or >15 000 per µL, a band count >1500 per µL, or an abnormal urinalysis. RESULTS: We identified 1876 cultures (1244 blood, 632 CSF) in 1145 infants aged ≤30 days; 901 (79%) of 1145 were hospitalized and 408 (45%) of 901 hospitalizations were for fever without source (FWS). Thirty-one (2.7%) of the 1145 infants had pathogenic cultures; 6 of 1145 infants (0.5% [95% confidence interval: 0.2-1.1]) had a time to notification >24 hours. All 6 patients had FWS (1.5% of hospitalized FWS sample) and met high-risk criteria on presentation. No low-risk patients had a time to notification >24 hours. Low-risk characteristics were found in 57% (232 of 408) of the entire hospitalized FWS population. CONCLUSIONS: Low-risk infants hospitalized for FWS or other concerns for serious bacterial infection may not need hospitalization for a full 48 hours simply to rule out bacteremia and bacterial meningitis.

Impact of a more restrictive approach to urinary tract imaging after febrile urinary tract infection.

OBJECTIVES: To determine the impact of using an algorithm requiring selective rather than routine urinary tract imaging following a first febrile urinary tract infection (UTI) on imaging use, detection of vesicoureteral reflux (VUR), prophylactic antibiotic use, and UTI recurrence within 6 months. DESIGN: Retrospective review comparing outcomes during periods before algorithm use (September 1, 2006, to August 31, 2007) and after algorithm use (September 1, 2008, to August 31, 2009). The new algorithm, which adapted recommendations from the United Kingdom's National Institute for Health and Clinical Excellence 2007 guidelines, was implemented in 2008. The algorithm calls for renal ultrasonography in most cases and restricts voiding cystourethrography for use in patients with certain risk factors. SETTING: County health system. PARTICIPANTS: Children younger than 2 years with a first febrile UTI. INTERVENTION: Selective algorithm for urinary tract imaging. MAIN OUTCOME MEASURES: Urinary tract imaging use, detection of VUR, prophylactic antibiotic use, and UTI recurrence within 6 months. RESULTS: After introduction of the new algorithm, voiding cystourethrography and prophylactic antibiotic use decreased markedly. Rates of UTI recurrence within 6 months and detection of grades 4 and 5 VUR did not change, but detection of grades 1 to 3 VUR decreased substantially. Patients in the prealgorithm group with grades 1 to 3 VUR who would have been missed with selective screening underwent no interventions other than successive urinary tract imaging and prophylactic antibiotic use. CONCLUSIONS: By restricting urinary tract imaging after an initial febrile UTI, rates of voiding cystourethrography and prophylactic antibiotic use decreased substantially without increasing the risk of UTI recurrence within 6 months and without an apparent decrease in detection of high-grade VUR. Clinicians can be more judicious in their use of urinary tract imaging.

Expert opinion: what to do when there is Coccidioides exposure in a laboratory.

Inadvertent exposure to Coccidioides species by laboratory staff and others as a result of a mishap is not an uncommon cause of infection in clinical microbiology laboratories. These types of infection may occur in laboratories outside the endemic areas, because the etiologic agent is unexpected in the submitted specimens and because personnel may be unfamiliar with the hazards of dealing with Coccidioides species in the laboratory. Coccidioidal infections are often difficult to treat, and outcomes can be poor. Here, we emphasize prevention and an approach to a laboratory accident that minimizes the risk of exposure to laboratory staff and staff in adjacent areas. On the basis of an artificially large exposure to arthroconidia that may occur as a result of a laboratory accident, a conservative approach of close observation and early treatment of exposed staff is discussed.

Halomonas, a newly recognized human pathogen causing infections and contamination in a dialysis center: three new species.

Our Renal Care Center (RCC) is a separate building, performing almost 2500 outpatient dialysis runs per month. In May 2007, 2 patients developed, days apart, bacteremia with an apparently identical nonfermentative Gram-negative rod. Because of difficulty identifying the organism, testing in the Biolog system identified them as a Halomonas species. Sequencing of approximately 1500 bases of the 16S rRNA gene in both organisms in 3 reference laboratories confirmed, searching against 3 databases, that the organisms were identical and were Halomonas species. There were 54 recognized species of this genus, associated with marine or saline sites. Initial attempts at environmental isolation as primary cultures, including a 4% salt agar plate, or initial incubation in 6.5% salt broth enrichment culture with subculture to agar, to exploit the halophilicity of Halomonas, were successful in demonstrating the colonies seen in the blood cultures, only from sites not contaminated with other organisms, because of competing growth. A more selective method was developed for use on samples suspected to be heavily contaminated with other organisms, using the strategy of increased salt concentration in a broth enrichment culture to further exploit Halomonas halotolerance, and thereby inhibit other organisms. A 16.5% salt concentration in brain-heart infusion broth, incubated at 35 degrees C for 48-72 hours, then subcultured to agar plates incubated in room air at 35 degrees C, proved optimal for selection and secondary isolation. With a combination of these techniques, 14/15 cultures of dialysates and 10/38 from the outflow pathways of the machines were Halomonas positive, compared to 0/31 cultures from the inflow side of the machines (including water supplies and storing, mixing, and preparation tanks). The exception was sites associated with or downstream of bicarbonate influx, 12/54 of which were positive. Two other local hospitals' dialysis centers, and our own inpatient dialysis facility, were cultured at sites that yielded Halomonas from our RCC, and Halomonas was not isolated. Further study by 16S rRNA gene sequencing and DNA-DNA hybridization revealed the cultures represented 3 novel species: 1 (H. stevensii sp. nov.) in the patients and environment and 2 (H. hamiltonii sp. nov., H. johnsoniae sp. nov.) in the environment, most closely related to H. magadiensis. Of 35 speciated isolates, 22 were H. stevensii, 10 H. johnsoniae, and 3 H. hamiltonii. We hypothesize that the RCC became contaminated with these halophilic organisms from bicarbonate used to prepare dialysis fluid, and they persist despite cleaning and flushing procedures because of biofilm in machines and bicarbonate fluid inflow sites. Our experience, together with the review of the literature presented here, indicates the genus Halomonas has pathogenic potential.

Dobutamine stress echocardiography is highly accurate for the prediction of contractile reserve in the early postoperative period, but may underestimate late recovery in contractile reserve after revascularization of the hibernating myocardium.

OBJECTIVE: We sought to investigate the accuracy of dobutamine stress echocardiography to predict the degree and timing of recovery in resting function and contractile reserve (CR) after revascularization of the hibernating myocardium. METHODS: In all, 24 patients with ischemic cardiomyopathy (ejection fraction < 40%) underwent dobutamine stress echocardiography 1 week before and 6 weeks, 3 months, and 6 months after coronary artery bypass grafting. RESULTS: Recovery rates at 6 weeks, 3 months, and 6 months postoperation were 21%, 33%, and 45% (P < .01) for resting function and 55%, 65%, and 74% (P < .01) for CR. Positive and negative predictive values for recovery of resting function and CR at 6 months postrevascularization were 66% vs 97% (P < .001) and 78% vs 48% (P < .001), respectively. Positive and negative predictive values were both high for recovery of CR at 6 weeks postrevascularization (89% and 78%). CONCLUSIONS: Dobutamine stress echocardiography can predict early recovery in CR postrevascularization with an excellent accuracy but may underestimate the degree of late recovery in CR.

Abo-incompatible heart transplantation in infants: the Freeman Hospital experience.

BACKGROUND: Incompatibility of the major blood groups A, B, and O has been an absolute contraindication for heart transplantation. However, because of immunologic immaturity, infants may have relative protection from hyperacute rejection and thus could undergo transplantation with ABO-mismatched organs. METHODS: Since January 2000, the authors have adopted a policy of considering infants for ABO-incompatible heart transplantation. Serum isohemagglutinin titers were measured before, during, and after transplantation. Two infants (3 and 2 months old) and a 21-month-old child underwent ABO-incompatible heart transplantation. During cardiopulmonary bypass, plasma exchange was performed. No other antibody-removal procedures were performed. A routine immunosuppressive regimen was used, and rejection was monitored by endomyocardial biopsies. An additional two patients (31 and 18 months old) were worked up but were unsuitable for ABO-incompatible transplantation because of high isohemagglutinin titers. They were successfully bridged to transplantation and received heart transplants from ABO-compatible donors. RESULTS: All three infants with ABO-incompatible heart transplants are fit and well, 40 months, 30 months, and 12 months postoperatively. All three had serum antibodies to antigens of the donor's blood group before transplantation. No hyperacute rejection occurred. No morbidity attributable to the ABO incompatibility has been observed. CONCLUSIONS: ABO-mismatched heart transplantation may be undertaken safely and without any short-term adverse consequences in infants and young children in whom isohemagglutinin production is not yet established.