Cutaneous Microbiome Profiles Following Chlorhexidine Treatment in a 72-Hour Daily Follow-Up Paired Design: a Pilot Study

Venous catheter-related bloodstream infections represent a significant problem in the United States. Our objective was to determine daily changes in skin microbiome profiles up to 72h postchlorhexidine treatment. Left and right forearm skin swab samples were obtained from 10 healthy volunteers over 72h at 24h intervals. Dorsal surface of left arm was treated with chlorohexidine gluconate (CHG) at initial time point (T = 0), while the right arm remained untreated (control). Swab samples were obtained shortly before (T = 0) and after CHG treatment (T = 24-48-72h). Bacterial DNA extraction, 16S rRNA gene V1-V3 sequencing and taxonomic annotation were performed using ZymoBIOMICS pipeline. PERMANOVA, linear discriminant and bacterial interaction network analyses were performed. A total of 13 total phyla, 273 genera, and 950 total species were detected across all time points, CHG-treated or CHG-untreated. Most abundant species included Cutibacterium acnes, Staphylococcus epidermidis, and Rothia Mucilaginosa. Low biomass-related inconsistent taxa detection was observed. PERMANOVA suggested a marginal difference between CHG-treated and CHG-untreated microbiome profiles (Genera: P(perm) = 0.0531; Species: P(perm) = 0.0450). Bacterial interaction network guided PERMANOVA analyses detected a microbiome change over time, suggesting a consistent CHG treatment-specific change. LEfSe identified Finegoldia magna, Bacillus pumilus, Bacillus thermoamylovorans as the only distinctive species. These species were more abundant and/or present post-CHG treatment in the CHG-treated group. These findings suggest that the skin microbiome was not significantly different 24, 48, or 72h after CHG treatment. Previous culture-based studies have found similar results after 24h. Future studies will be needed to determine the mechanisms of bacterial regrowth after CHG treatment. IMPORTANCE Annually, over 80,000 central line infections occur in the United States. Understanding the pathogenesis of these infections is crucial. Chlorhexidine is the most commonly used skin preparation before line placement. We hypothesized that the use of chlorhexidine and dressings will alter the normal arm skin microbiome over a period of 72h. We used 16S-rRNA gene next generation sequencing (NGS) to determine the forearm skin microbiome of volunteers. The left arm was swabbed with chlorhexidine and the right arm served as control. The skin microbiome returned to normal after 24h. Our NGS results confirm findings of two previous culture-based studies. Relative abundance of Bacillus spp. in the chlorhexidine-treated samples was increased, consistent with one previous study. Based on the results of this pilot study, we will need to measure viable bacteria during a 24h time course following chlorhexidine treatment to understand the source of skin microbiome replenishment.

The association of penicillin allergy with outcomes after open ventral hernia repair

BACKGROUND

Up to 11% of patients report a penicillin allergy (PA), with 1-2% demonstrating a true IgE mediated allergy upon testing. PA patients often receive non-beta-lactam antibiotic surgical prophylaxis (non-BLP). This study evaluates the relationship of PA to outcomes after open ventral hernia repair (OVHR).

METHODS

A prospective institutional database was queried for patients undergoing OVHR. Demographics, operative characteristics, and outcomes were evaluated by the reported PA and the administration of beta-lactam prophylaxis (BLP).

RESULTS

Allergy histories were reviewed in 1178 patients. PA was reported in 21.6% of patients, with 55.5% reporting rash or hives, 15.0% airway compromise or anaphylaxis, and 29.5% no specific reaction. BLP was administered to 76.3% of patients, including 22.1% of PA patients and 89.9% of patients without PA. PA patients were more often female (64.6% PA patients vs. 56% non-PA, p = 0.01), with higher rates of chronic steroids, MRSA, anxiety, asthma, COPD, chronic pain, and sleep apnea (p < 0.03 all values). PA patients had higher rates of contaminated cases, including mesh infection and fistula. Of the 683 clean cases, 82.1% received BLP. Of the 117 clean contaminated cases (CDC wound class 2), 82.9% received BLP, which was associated with reduced long-term readmission for hernia complications (21.5 vs. 55%, p = 0.002, OR 0.27, CI 0.09-0.83). In the 120 CDC wound class 3 and 4 patients, 65.8% received BLP. In multivariate analysis, BLP was associated with lower rates of reoperation (OR 0.31, CI 0.12-0.76) and recurrence (OR 0.32, CI 0.11-0.86). BLP was given to 22.1% of the PA patients with no adverse reactions noted.

CONCLUSION

PA patients had more comorbidities and complex ventral hernias. When controlling for contamination and MRSA history, BLP is associated with improved outcomes particularly in contaminated cases. PA may be a risk factor for patient complexity, and further studies are warranted to determine if allergy testing can be warranted in known or anticipated contaminated cases.

Doing the Same with Less: A Randomized, Multinational, Open-Label, Adjudicator-Blinded Trial of an Algorithm vs. Standard of Care to Determine Treatment Duration for Staphylococcal Bacteremia

Background

The appropriate duration of antibiotics for staphylococcal bloodstream infection (BSI) is unknown. An algorithm to identify patients with staphylococcal BSI who can be safely treated with shorter courses of therapy would improve care and reduce total antibiotic use.

Methods

Adult patients with staphylococcal BSI were randomized to treatment based on algorithm-based therapy (ABT) or to standard of care (SOC). Co-primary outcomes were clinical success, as determined by a blinded Adjudication Committee, and serious adverse event (SAE) rates. The prespecified secondary outcome measure was antibiotic days by treatment group, among patients without complicated BSI. Prespecified durations of therapy in ABT were: S. aureus BSI (SAB): uncomplicated: 14 days; complicated: 4–6 weeks. Coagulase-negative staphylococci BSI (CoNSB): simple (1 positive blood culture) (0–3 days), uncomplicated (&gt;1 positive blood culture) (5 days), complicated (7–28 days). Outcomes were compared using intention-to-treat principles. The target sample size was 500 patients, to ensure 90% power for establishing noninferiority within a margin of 15%.

Results

Between April 2011 and March 2017, 509 adults with suspected staphylococcal BSI at 16 sites in the US and Spain were randomized to ABT (N = 255) or SOC (N = 254). There were 116 patients with SAB (23%) and 385 (76%) with CoNSB (Figure 1). Overall success rate in the ABT group was 82.0% vs. 81.5% in the SOC group, difference 0.5%, 95% CI −5.2% to 6.1%. SAEs were reported in 32.9% of ABT vs. 28.3% of SOC patients (OR 1.2, 95% CI 0.9 to 1.8). Among evaluable patients without complicated BSI, mean duration of therapy was 4.4 days in the ABT group vs. 6.4 days in the SOC group (difference −2.0 days, 95% CI −3.3 to −-0.7, P = 0.003). Among patients with uncomplicated SAB, treatment durations were similar (15.3 days in ABT vs. 16.3 days in SOC, difference −1 day, 95% CI −3.89 to 1.91, P = 0.497), whereas for uncomplicated CoNSB, duration was shorter in the ABT group (5.3 days in ABT vs. 8.4 days in SOC, difference −3 days, 95% CI −4.87 to −1.34, P &lt; 0.001).

Conclusion

The use of a treatment algorithm for staphylococcal BSI was associated with significant reductions in duration of antibiotic therapy in patients without complicated BSI, without significant differences in overall success or SAEs.

Disclosures

V. Fowler Jr., NIH: Investigator, Contract HHSN272200900023C

The cutaneous microbiome in outpatients presenting with acute skin abscesses

BACKGROUND

Previous studies have demonstrated an association between antibiotic use and the development of skin abscesses. We tested the hypothesis that alterations in the composition of the cutaneous microbiota may predispose individuals to skin abscesses.

METHODS

We studied 25 patients with skin abscesses and 25 age-matched controls, who each completed a questionnaire. Skin swab samples were obtained for DNA analysis from 4 sites around the abscess site (hereafter, "peri-abscess specimens") and from similar sites on the patient's contralateral side and on healthy control subjects. DNA was extracted and analyzed by quantitative polymerase chain reaction (qPCR) and high-throughput sequencing. The purulent abscess drainage was sent for culture.

RESULTS

Fifteen patients with abscess were infected with Staphylococcus aureus. Use of nuc qPCR to quantitate S. aureus revealed a significantly greater frequency of positive results for peri-abscess and contralateral skin samples, compared with control skin specimens. Analysis of community structure showed greater heterogeneity in the control samples than in the peri-abscess and contralateral samples. Metagenomic analysis detected significantly more predicted genes related to metabolic activity in the peri-abscess specimens than in the control samples.

CONCLUSIONS

The peri-abscess microbiome was similar to the contralateral microbiome, but both microbiomes differed from that for control patients. Host characteristics affecting microbial populations might be important determinants of abscess risk.

Comparison of culture and molecular techniques for microbial community characterization in infected necrotizing pancreatitis

BACKGROUND

Infected necrotizing pancreatitis is associated with significant morbidity and mortality. Peripancreatic fluid cultures may fail to identify all the infecting organisms. The aim of this study was to compare the bacterial biome of peripancreatic fluid from infected necrotizing pancreatitis patients using 16S ribosomal RNA (rRNA) DNA deep sequencing and quantitative polymerase chain reaction (qPCR) targeting the 16S rRNA gene versus standard laboratory culture.

MATERIALS AND METHODS

Peripancreatic fluid was collected during operative or radiologic intervention and samples sent for culture. In parallel, microbial DNA was extracted, qPCR targeting the 16S rRNA gene and 16S rRNA PCR amplification followed by Illumina deep sequencing were performed.

RESULTS

Using culture techniques, the bacterial strains most frequently identified were gram-negative rods (Escherichia coli, Klebsiella pneumoniae) and Enterococcus. Samples in which culture results were negative had copy numbers of the 16S rRNA gene close to background in qPCR analysis. For samples with high bacterial load, sequencing results were in some cases in good agreement with culture data, whereas in others there were disagreements, likely due to differences in taxonomic classification, cultivability, and differing susceptibility to background contamination. Sequencing results appeared generally unreliable in cases of negative culture where little microbial DNA was input into qPCR sequencing reactions.

CONCLUSIONS

Both sequencing and culture data display their own sources of bias and potential error. Consideration of data from multiple techniques will yield a more accurate view of bacterial infections than can be achieved by any single technique.

The major genetic determinants of HIV-1 control affect HLA class I peptide presentation

Infectious and inflammatory diseases have repeatedly shown strong genetic associations within the major histocompatibility complex (MHC); however, the basis for these associations remains elusive. To define host genetic effects on the outcome of a chronic viral infection, we performed genome-wide association analysis in a multiethnic cohort of HIV-1 controllers and progressors, and we analyzed the effects of individual amino acids within the classical human leukocyte antigen (HLA) proteins. We identified >300 genome-wide significant single-nucleotide polymorphisms (SNPs) within the MHC and none elsewhere. Specific amino acids in the HLA-B peptide binding groove, as well as an independent HLA-C effect, explain the SNP associations and reconcile both protective and risk HLA alleles. These results implicate the nature of the HLA-viral peptide interaction as the major factor modulating durable control of HIV infection.

Etiology of illness in patients with severe sepsis admitted to the hospital from the emergency department

BACKGROUND

Patients identified with sepsis in the emergency department often are treated on the basis of the presumption of infection; however, various noninfectious conditions that require specific treatments have clinical presentations very similar to that of sepsis. Our aim was to describe the etiology of illness in patients identified and treated for severe sepsis in the emergency department.

METHODS

We conducted a prospective observational study of patients treated with goal-directed resuscitation for severe sepsis in the emergency department. Inclusion criteria were suspected infection, 2 or more criteria for systemic inflammation, and evidence of hypoperfusion. Exclusion criteria were age of <18 years and the need for immediate surgery. Clinical data on eligible patients were prospectively collected for 2 years. Blinded observers used a priori definitions to determine the final cause of hospitalization.

RESULTS

In total, 211 patients were enrolled; 95 (45%) had positive culture results, and 116 (55%) had negative culture results. The overall mortality rate was 19%. Patients with positive culture results were more likely to have indwelling vascular lines (P = .03), be residents of nursing homes (P = .04), and have a shorter time to administration of antibiotics in the emergency department (83 vs 97 min; P = .03). Of patients with negative culture results, 44% had clinical infections, 8% had atypical infections, 32% had noninfectious mimics, and 16% had an illness of indeterminate etiology.

CONCLUSION

In this study, we found that >50% of patients identified and treated for severe sepsis in the emergency department had negative culture results. Of patients identified with a sepsis syndrome at presentation, 18% had a noninfectious diagnosis that mimicked sepsis, and the clinical characteristics of these patients were similar to those of patients with culture-positive sepsis.

Prospective external validation of the clinical effectiveness of an emergency department-based early goal-directed therapy protocol for severe sepsis and septic shock

OBJECTIVE

To determine the clinical effectiveness of implementing early goal-directed therapy (EGDT) as a routine protocol in the emergency department (ED).

METHODS

Prospective interventional study conducted over 2 years at an urban ED. Inclusion criteria included suspected infection, criteria for systemic inflammation, and either systolic BP < 90 mm Hg after a fluid bolus or lactate concentration >/= 4 mol/L. Exclusion criteria were age < 18 years, contraindication to a chest central venous catheter, and need for immediate surgery. We prospectively recorded preintervention clinical and mortality data on consecutive, eligible patients for 1 year when treatment was at the discretion of board-certified emergency physicians. We then implemented an EGDT protocol (the intervention) and recorded clinical data and mortality rates for 1 year. Prior to the first year, we defined a 33% relative reduction in mortality (relative mortality reduction that was found in the original EGDT trial) to indicate clinical effectiveness of the intervention.

RESULTS

We enrolled 79 patients in the preintervention year and 77 patients in the postintervention year. Compared with the preintervention year, patients in the postintervention year received significantly greater crystalloid volume (2.54 L vs 4.66 L, p < 0.001) and frequency of vasopressor infusion (34% vs 69%, p < 0.001) during the initial resuscitation. In-hospital mortality was 21 of 79 patients (27%) before intervention, compared with 14 of 77 patients (18%) after intervention (absolute difference, - 9%; 95% confidence interval, + 5 to - 21%).

CONCLUSIONS

Implementation of EGDT in our ED was associated with a 9% absolute (33% relative) mortality reduction. Our data provide external validation of the clinical effectiveness of EGDT to treat sepsis and septic shock in the ED.

Recurrent pneumococcal pneumonia in an HIV-positive patient with lymphoid interstitial pneumonitis

Lymphoid interstitial pneumonitis (LIP) is a rare complication of AIDS in adults. Patients with AIDS and LIP are at high risk for bacterial pneumonia caused by Streptococcus pneumoniae, Haemophilus influenzae, and Staphylococcus aureus. We have described an HIV-positive patient with LIP complicated by recurrent pneumonia due to Streptococcus pneumoniae; recurrence was apparently prevented by maintenance penicillin therapy.

Growth of Leishmania donovani amastigotes in the continuous human macrophage cell line U937: studies of drug efficacy and metabolism

We have developed a simple and reproducible system for infecting a human macrophage cell line (U937) with stationary-phase Leishmania donovani promastigotes. Four days after infection, greater than 90% of the promastigotes had transformed to amastigotes. The antileishmanial agents allopurinol riboside, formycin B, 9-deazainosine, and sodium stibogluconate effectively inhibited the growth of L. donovani amastigotes in this cell line. To study the capability of amastigotes in the U937 cell line to carry out biochemical reactions that could be monitored experimentally, we incubated the cells with radiolabeled 9-deazainosine. This purine analogue underwent metabolism in the amastigote phase similar to that occurring in the promastigote phase. This cell line should be useful for studies of parasite maturation and differentiation, parasite-human interactions, and antiparasitic drugs.

The spectrum of relapsing fever in the Rocky Mountains

Between 1940 and 1976, two cases of tick-borne relapsing fever were reported in Colorado, but since 1977, 23 confirmed cases have occurred. All patients had fever, with a mean of 2.8 febrile episodes (range, one to six). Complications included thrombocytopenia, endophthalmitis, meningitis, abortion, in utero infection, and erythema multiforme. All treated patients were eventually cured with antibiotics, although two pregnant patients failed to be cured by their initial courses of antibiotics. Seven of 21 treated patients had Jarisch-Herxheimer reactions, three of whom required intensive care. Five of nine patients who received tetracycline at an initial dose of 5 mg/kg or more had reactions v none of four patients treated with lower doses. Possible causes of the recent increased incidence include increased physician awareness and reporting, improved diagnostic techniques, and an actual increase due to a larger population at risk. Because summertime visits to the Rocky Mountains are becoming increasingly popular, physicians elsewhere should know how to recognize and treat this condition.

Pneumonia in the elderly

The organisms to which the elderly are most susceptible are different from those affecting younger pneumonia patients. Furthermore, the pathogenesis of the disease varies with age, partly because of an increased incidence of underlying disease in older persons and partly because of the effects of the aging process itself. Presenting symptoms of pneumonia may be more subtle in the elderly than in younger patients, and clinical findings may also vary. Elderly pneumonia patients should always be hospitalized and treated immediately and aggressively with parenteral antibiotics according to results of the Gram stain. Once the pathogen involved is identified, more specific antibiotic therapy is begun. If physicians understand the unique characteristics of pneumonia in the elderly and act accordingly, they should play an important part in decreasing the relatively high mortality from the disease in this age-group.

The immediate care of head injuries

Anaesthetists have much to contribute as members of a team concerned with the management of a severe head injury. Many factors have been discussed but it must be remembered that their most important duty is to maintain a clear airway.