Risk factors for mortality after linezolid treatment of vancomycin-resistant Enterococcus bloodstream infection.

OBJECTIVES: We analyzed the risk factors affecting linezolid treatment outcome in vancomycin-resistant Enterococcus (VRE) bloodstream infection (BSI). METHODS: We conducted a multicenter observational study of patients who received linezolid 600 mg every 12 hours for VRE BSI. The primary outcome was 28-day mortality. The estimated area under the concentration-time curve and trough concentration were calculated. Multivariable logistic regression was used for the outcome analysis. RESULTS: A total of 170 patients were included: 114 (67.1%) survived and 56 (32.9%) did not. A total of 26 (18.2%) isolates showed a linezolid minimum inhibitory concentration (MIC) of ≤1 mg/l, 113 (79.0%) of 2 mg/l, and 4 (2.8%) of 4 mg/l. The univariable analysis showed that the linezolid MIC and concentration-time curve/MIC were not associated with mortality (P = 0.95 and P = 0.42, respectively). After adjusting for underlying comorbidity and disease severity, the linezolid dose per body weight (LDBW), body height, and interaction between them were independent risks for mortality. Marginal analysis showed that increasing the LDBW was protective in patients with a body height <160 cm. A trough concentration of >12.2 mg/l was a risk factor for thrombocytopenia. CONCLUSION: The LDBW and body height were interactively associated with clinical outcomes of linezolid treatment for VRE BSI.

Clonality of Fluconazole-Nonsusceptible Candida tropicalis in Bloodstream Infections, Taiwan, 2011-2017.

Candida tropicalis is the leading cause of non-C. albicans candidemia in tropical Asia and Latin America. We evaluated isolates from 344 patients with an initial episode of C. tropicalis candidemia. We found that 58 (16.9%) patients were infected by fluconazole-nonsusceptible (FNS) C. tropicalis with cross resistance to itraconazole, voriconazole, and posaconazole; 55.2% (32/58) of patients were azole-naive. Multilocus sequence typing analysis revealed FNS isolates were genetically closely related, but we did not see time- or place-clustering. Among the diploid sequence types (DSTs), we noted DST225, which has been reported from fruit in Taiwan and hospitals in Beijing, China, as well as DST376 and DST505-7, which also were reported from hospitals in Shanghai, China. Our findings suggest cross-boundary expansion of FNS C. tropicalis and highlight the importance of active surveillance of clinical isolates to detect dissemination of this pathogen and explore potential sources in the community.

In Vitro Evaluation of Povidone-Iodine and Chlorhexidine against Outbreak and Nonoutbreak Strains of Mycobacterium abscessus Using Standard Quantitative Suspension and Carrier Testing.

Povidone-iodine (PI) and chlorhexidine (CHX) are widely used antiseptics active against conventional Staphylococcus aureus, Enterobacteriaceae, Candida species, and viruses, but their efficacy against Mycobacterium abscessus remains unproven. We determined the in vitro potency of alcoholic PI and CHX against M. abscessus subsp. abscessus (ATCC 19977), M. abscessus subsp. bolletii (BCRC 16915), and our outbreak strain of M. abscessus subsp. massiliense (TPE 101) in reference to Staphylococcus aureus (ATCC 29213) by standard quantitative suspension and carrier methods (EN 14563). By suspension, all mycobacterial strains compared to S. aureus were significantly more resistant to CHX, but not PI. By carrier, the mean logarithmic reductions (LR) achieved by PI under clean (dirty) conditions were 6.575 (2.482), 5.540 (2.298), 4.595 (1.967), and 1.173 (0.889), while those achieved by CHX under clean (dirty) conditions were 3.164 (5.445), 5.307 (2.564), 3.844 (2.232), and 0.863 (0.389) for S. aureus, M. abscessus subsp. bolletii, M. abscessus subsp. abscessus, and M. abscessus subsp. massiliense, respectively. M. abscessus subsp. massiliense (outbreak strain) was significantly more resistant than the other tested strains to PI and CHX. By both methods, the mean LR achieved by PI was higher than for CHX for all mycobacterial strains, but under dirty conditions, neither antiseptic was effectively mycobactericidal (LR < 5). These preliminary findings caution against the universal replacement of PI with CHX as the first-line skin antiseptic, since all M. abscessus isolates were resistant to CHX. More studies are needed to establish the best practice for skin antisepsis if mycobacterial infections are also to be prevented.

Risk of recurrent nontyphoid Salmonella bacteremia in human immunodeficiency virus-infected patients with short-term secondary prophylaxis in the era of combination antiretroviral therapy.

BACKGROUND/PURPOSE: Nontyphoid Salmonella (NTS) bacteremia causes high mortality and recurrence rates in human immunodeficiency virus (HIV)-infected patients. This study aimed to investigate the risk of recurrent NTS bacteremia in the era of combination antiretroviral therapy (cART). METHODS: The medical records of consecutive HIV-infected patients with NTS bacteremia from January 2006 to June 2014 were reviewed. The patients were divided into two groups: patients who achieved a decline of plasma HIV RNA load by ≥ 2 log10 after 4 weeks of cART (good short-term virological response) and those who failed to achieve the goal (poor short-term virological response). Clinical information was collected on the demographics, immunological and virological responses, prophylactic antibiotics used, episodes of recurrent NTS bacteremia, and mortality. RESULTS: During the study period, 49 patients with 52 episodes of NTS bacteremia were included: 29 patients in the good virological response group, in which 16 received secondary prophylaxis; and 20 patients in the poor response group, in which 15 received secondary prophylaxis. There were no recurrent episodes of NTS bacteremia in the good-response group, whereas the incidence rate of recurrent NTS bacteremia was 5.21 per 100 person-years and 56.42 per 100 person-years of follow-up in patients receiving and not receiving prophylaxis, respectively, in the poor-response group. No patients died in the good-response group, whereas five patients (25%) in the poor-response group died. The resistance rate of 52 NTS isolates tested to ciprofloxacin was 7.7%. CONCLUSION: The risk of recurrent NTS bacteremia is low in HIV-infected patients who achieve short-term virological response to cART, regardless of secondary prophylaxis.

Excess Mortality Associated With Colistin-Tigecycline Compared With Colistin-Carbapenem Combination Therapy for Extensively Drug-Resistant Acinetobacter baumannii Bacteremia: A Multicenter Prospective Observational Study.

OBJECTIVES: Since few therapeutic options exist for extensively drug resistant Acinetobacter baumannii, an emerging threat in ICUs worldwide, and comparative prospective studies of colistin-based combination therapies are lacking, our objective was to compare the outcomes of patients with extensively drug-resistant A. baumannii bacteremia, treated with colistin-carbapenem and colistin-tigecycline combinations. DESIGN: Prospective, observational, multicenter study. SETTING, PATIENTS, AND INTERVENTIONS: Adults with extensively drug-resistant A. baumannii bacteremia were prospectively followed from 2010 to 2013 at three hospitals in Taiwan. Extensively drug-resistant A. baumannii was defined as A. baumannii (genospecies 2) nonsusceptible to all drug classes except for colistin and tigecycline, and standard combination therapy as use of parenteral colistin-carbapenem or colistin-tigecycline for at least 48 hours after onset of bacteremia. MEASUREMENTS AND MAIN RESULTS: Primary outcome measure was 14-day mortality. Of the 176 episodes of extensively drug-resistant A. baumannii bacteremia evaluated, 55 patients with a median (interquartile range) age of 62 years (44-79 yr) and Sequential Organ Failure Assessment score of 9 (5-13) points received standard combination therapy: colistin-tigecycline in 29 patients and colistin-carbapenem in 26. Crude 14-day and in-hospital mortality rates for patients receiving colistin-tigecycline versus patients receiving colistin-carbapenem were 35% versus 15% (p=0.105) and 69% versus 50% (p=0.152), respectively. Breakthrough extensively drug-resistant A. baumannii bacteremia under steady state concentrations of combination therapy for colistin-tigecycline group was 18% and for colistin-carbapenem group was 0% (p=0.059). Eleven patients (20.0%) developed nephrotoxicity. After adjusting for age, sex, comorbidity, initial disease severity, loading colistin dose, polymicrobial infection, and primary infection site, excess 14-day mortality was associated with the use of colistin-tigecycline in the subgroup with tigecycline minimum inhibitory concentration greater than 2 mg/L compared with the use of colistin-carbapenem (hazard ratio, 6.93; 95% CI, 1.61-29.78; p=0.009). CONCLUSIONS: Increased 14-day mortality was associated with colistin-tigecycline therapy given tigecycline minimum inhibitory concentration greater than 2 mg/L compared with colistin-carbapenem therapy for extensively drug-resistant A. baumannii bacteremia.

Effectiveness of tigecycline-based versus colistin- based therapy for treatment of pneumonia caused by multidrug-resistant Acinetobacter baumannii in a critical setting: a matched cohort analysis.

BACKGROUND: Colistin and tigecycline have both been shown good in vitro activity among multi-drug resistant Acinetobacter baumannii (MDRAB). A comparative study of colistin versus tigecycline for MDRAB pneumonia is lacking. METHODS: The study enrolled adults with MDRAB pneumonia admitted to intensive care units at a referral medical center during 2009-2010. Since there were no standardized minimum inhibitory concentration (MIC) interpretation criteria of tigecycline against A. baumannii, MIC of tigecycline was not routinely tested at our hospital. During the study periods, MIC of colistin was not routinely tested also. We consider both colistin and tigecycline as definite treatments of MDRAB pneumonia. Patients who received tigecycline were selected as potential controls for those who had received colistin. We performed a propensity score analysis, by considering the criteria of age, gender, underlying diseases, and disease severity, in order to match and equalize potential prognostic factors and severity in the two groups. RESULTS: A total of 294 adults with MDRAB pneumonia were enrolled, including 119 who received colistin and 175 who received tigecycline. We matched 84 adults who received colistin with an equal number of controls who received tigecycline. The two well matched cohorts share similar characteristics: the propensity scores are colistin: 0.37 vs. tigecycline: 0.37, (P = .97); baseline creatinine (1.70 vs. 1.81, P = .50), and the APACHE II score (21.6 vs. 22.0, P = .99). The tigecycline group has an excess mortality of 16.7% (60.7% vs. 44%, 95% confidence interval 0.9% - 32.4%, P = .04). The excess mortality of tigecycline is significant only among those with MIC >2 µg/mL (10/12 vs. 37/84, P = .01), but not for those with MIC ≦ 2 µg/mL (4/10 vs. 37/84, P = .81). CONCLUSIONS: Our data disfavors the use of tigecycline-based treatment in treating MDRAB pneumonia when tigecycline and colistin susceptibilities are unknown, since choosing tigecycline-based treatment might result in higher mortality. The excess mortality of tigecycline-based group may be related to higher MIC of tigecycline (> 2 µg/mL). Choosing tigecycline empirically for treating MDRAB pneumonia in the critical setting should be cautious.

The Madin-Darby canine kidney cell culture derived influenza A/H5N1 vaccine: a phase I trial in Taiwan.

BACKGROUND: Avian H5N1 influenza has caused human infections globally and has a high mortality rate. Rapid production of effective vaccines is needed. METHODS: A phase 1, randomized, observer-blinded clinical trial was conducted to examine the safety and immunogenicity of an inactivated whole virion vaccine against the influenza A/H5N1 virus produced from the Madin-Darby canine kidney (MDCK) cell line. Participants were randomized to four groups and administered two intramuscular doses of vaccine containing 3 µg hemagglutinin (HA), 3 µg HA with 300 µg aluminum phosphate (AlPO4), 6 µg HA, and 6 µg HA with 300 µg AlPO4, respectively, at two visits, 21 days apart. Serum hemagglutination inhibition (HAI) and neutralizing antibody levels were determined at baseline and on Days 21 and 42. RESULTS: Sixty healthy individuals were enrolled. The neutralization assay showed a significant immune response in the 6 µg with ALPO4 group on Day 42 compared to pre-vaccination levels (11.32±9.77 vs. 4.00±0, p=0.02). The adjuvant effect in neutralization assay was also significant on Day 42 in the 6 µg group (4.52±1.94 without adjuvant vs. 11.32±9.77 with adjuvant, p=0.02). HAI assay also showed an aluminum adjuvant-induced increasing trend in HAI geometric mean titer on Day 42 in the 3 µg and 6 µg groups (6.02 versus 8.20, p=0.05 and 5.74 versus 8.21, p=0.14). The most frequent adverse event was local pain (20% to 60%). There were no vaccine-related severe adverse effects. CONCLUSION: MDCK cell line-derived H5N1 vaccine was well tolerated. It is necessary to investigate further the immunogenicity of higher antigen doses and the role of aluminum adjuvant in augmenting the effect of the vaccine.

Loading dose required to achieve rapid therapeutic teicoplanin trough plasma concentration in patients with multidrug-resistant gram-positive infections.

Teicoplanin is an antibiotic drug prescribed for the treatment of multidrug-resistant Gram-positive infections. However, there is currently no consensus as to the optimal teicoplanin loading dose. The objective of this study was to compare plasma concentrations of teicoplanin in patients with multidrug-resistant Gram-positive infections after the administration of two different loading doses. Two groups of patients were infused intravenously with four loading doses of 6 mg/kg body-weight (group A, n = 12) or 12 mg/kg body-weight (group B, n = 11). The first three loading doses were administered at 12-hr intervals, and the fourth was given 24 hr after the third dose. Maintenance doses of 6 mg/kg were administered every day, every other day or every third day depending on the individual's creatinine clearance, and teicoplanin trough plasma concentrations were monitored. Only samples obtained on the same day for both groups were compared statistically. A higher percentage of group B patients achieved the desired therapeutic concentration of teicoplanin (C(min.)  ≥ 10 mg/L) on days 2 and 3 (90.0% and 100%, respectively) compared with patients in group A (18.2% and 16.7%, respectively) (p < 0.001). In addition, more patients in group B achieved therapeutic concentrations from days 2 through 12. In conclusion, despite limitations in drawing definitive conclusions because of a relatively small sample size and variability in renal impairment among patients, our findings suggest that a teicoplanin loading dose of 12 mg/kg body-weight results in a safe and rapid attainment of therapeutic trough plasma concentrations. This regimen may enhance treatment efficacy.

Immunogenicity and safety of an AS03(A)-adjuvanted H5N1 influenza vaccine in a Taiwanese population.

BACKGROUND/PURPOSE: A multicenter study (NCT00449670) conducted across Taiwan, Singapore, Hong Kong and Thailand evaluated the safety and manufacturing consistency of four formulations of an AS03(A)-adjuvanted H5N1 vaccine in terms of immune response against the vaccine-homologous strain (A/Vietnam/1194/2004). This manuscript presents data from the Taiwanese population. METHODS: A total of 400 individuals, aged 18-60 years, were randomized into six groups (2:2:2:2:1:1 ratio) to receive two doses (21 days apart) of one of the four adjuvanted formulations (H5N1-AS03(A)-groups) or one of the two nonadjuvanted formulations (H5N1-DIL-groups). Blood samples collected before vaccination (Day 0) and 21 days after each vaccine dose were analyzed using hemagglutination inhibition (HI) assay. Adverse events were recorded. RESULTS: All four AS03(A)-adjuvanted formulations induced comparable immune responses against the A/Vietnam/1194/2004 strain; following the second dose, immune response in terms of HI antibodies was higher in the H5N1-AS03(A)-groups {seroprotection rate=91.6% [95% confidence interval (CI): 87.9-94.4]; geometric mean titer (GMT)=177.6 (95% CI: 153.2-206.0)} compared with the H5N1-DIL-groups [seroprotection rates=5.0% (95% CI: 1.4-12.3); GMT=6.3 (95% CI: 5.4-7.4)]. Immune response against the heterologous A/Indonesia/05/2005 strain was also stronger in the H5N1-AS03(A)-groups [seroprotection rate=45.6% (95% CI: 40.0-51.4); GMT=20.5 (95% CI: 17.8-23.7)] compared with the H5N1-DIL groups [seroprotection rate=0.0% (95% CI: 0.0-4.5); GMT=5.0 (95% CI: 5.0-5.0)]. The overall reactogenicity profile of the adjuvanted formulations was clinically acceptable. CONCLUSION: The AS03(A)-adjuvanted H5N1 influenza vaccine formulations induced stronger immune response against the vaccine-homologous and heterologous strains than the nonadjuvanted formulations. The AS03(A)-adjuvanted H5N1 vaccine demonstrated a good immunogenicity and an acceptable safety profile in the Taiwanese population.

Risk of recurrent nontyphoid Salmonella bacteremia in HIV-infected patients in the era of highly active antiretroviral therapy and an increasing trend of fluoroquinolone resistance.

BACKGROUND: Risk of recurrent nontyphoid Salmonella (NTS) bacteremia and trends of antimicrobial resistance of NTS remain unknown in human immunodeficiency virus (HIV)-infected patients receiving highly active antiretroviral therapy (HAART). METHODS: Ninety-three patients who received a diagnosis of NTS bacteremia from June 1994 through June 2006 were prospectively followed up. Incidence of recurrent NTS bacteremia was compared between the pre-HAART era (June 1994-March 1997) and the HAART era (April 1997-June 2006). Prevalence of antimicrobial resistance was compared among the NTS isolates obtained in the pre-HAART era, the early HAART era (April 1997-June 2002), and the late HAART era (July 2002-June 2006). RESULTS: Compared with patients enrolled in the pre-HAART era, patients who received HAART had an incidence of recurrent NTS bacteremia that was significantly reduced by 96%; the incidence of recurrent NTS bacteremia was 2.56 cases per 100 person-years in the HAART era, compared with 70.56 cases per 100 person-years in the pre-HAART era (rate ratio, 0.036; 95% confidence interval, 0.012-0.114; P<.001). In the HAART era, the incidence of recurrent NTS bacteremia did not increase among patients receiving fluoroquinolone prophylaxis for 30 days (3.95 cases per 100 person-years), with a rate ratio of 0.43 (95% confidence interval, 0.07-2.58). Although resistance to ampicillin, cotrimoxazole, and chloramphenicol decreased, the proportion of NTS isolates resistant to fluoroquinolones increased from 0% in the pre-HAART era to 6.2% in the early HAART era and 34.2% in the late HAART era (P=.002). CONCLUSIONS: The risk of recurrent NTS bacteremia decreased significantly in the HAART era, although NTS isolates obtained from HIV-infected patients were increasingly resistant to fluoroquinolones.

Successful treatment of imported cerebral malaria with artesunate-mefloquine combination therapy.

Treatment of cerebral malaria with intravenous quinine is frequently associated with life-threatening cardiotoxicity. We report a case of imported cerebral malaria successfully treated with artesunate-mefloquine combination therapy. The 27-year-old woman presented with fever, sudden onset of binocular blindness and altered consciousness 10 days after a short stay in Indonesia. Hyperparasitemia with Plasmodium falciparum and P. vivax in more than 5% of red blood cells was demonstrated on peripheral blood smear. She was admitted to the intensive care unit due to shock, jaundice and acute renal failure. Because of a shortage of intravenous quinine, intravenous artesunate was given as an alternative. Her condition stabilized on the 3rd day of therapy, with resolution of fever and disappearance of parasitemia. Consolidation therapy with oral mefloquine and primaquine was then given to prevent recrudescence and relapse. The only adverse event associated with artesunate was transient reticulocytopenia, which resolved after discontinuation of therapy. Her vision completely recovered, along with renal and liver function.

Acute urethritis and arthritis-dermatitis syndrome due to Neisseria meningitidis.

Acute urethritis and arthritis-dermatitis syndrome after sexual contact are often assumed to be caused by Neisseria gonorrhoeae. We report a case of arthritis-dermatitis syndrome in a 32-year-old man who presented with generalized maculopapular and petechial skin lesions and polyarthritis. Acute urethritis developed 1 week after oro-genital sexual contact with a sex worker about 3 weeks before admission. No pathogen was found on smear of urethral discharge and skin lesions, but Gram-negative diplococci were noted in joint fluid, and blood culture yielded N. meningitidis. His condition improved gradually after repeated arthrocentesis and antibiotic therapy with ceftriaxone followed by ciprofloxacin. Oro-genital contact is a transmission route for N. meningitidis infection manifesting as acute urethritis and arthritis-dermatitis syndrome.

High-level expression of ampC beta-lactamase due to insertion of nucleotides between -10 and -35 promoter sequences in Escherichia coli clinical isolates: cases not responsive to extended-spectrum-cephalosporin treatment.

Two Escherichia coli isolates were recovered from the blood of two cancer patients and were demonstrated to produce high levels of the AmpC beta-lactamase with isoelectric points of >9.0. The hypertranscription of ampC RNA was observed by Northern blot hybridization in both isolates. One isolate (isolate EC44) had a point mutation (G-->A at position -28) and insertion of thymidine between positions -20 and -19 of the ampC promoter gene (GenBank accession no. AE000487). The single nucleotide insertion of T between positions -19 and -20 created an optimal distance (17 bp) in the Pribnow box for ampC hyperproduction. The other isolate (isolate EC38) had two point mutations (G-->A at position -28 and C-->T at position +58) and a 2-base (GT) insertion between positions -14 and -15. Although the insertion of GT between positions -14 and -15 may create a new promoter next to the original promoter, cloning of the ampC region with truncated nucleotides of the original -35 region of EC38 failed to verify the hypothesis that a new promoter would be created by such a nucleotide insertion. Instead, multiple start sites for ampC transcription at -1, +1, +2, and +3 were observed in an S1 nuclease protection assay. These results suggest that the RNA polymerase is flexible in the selection of a start site in ampC hypertranscription. In conclusion, nucleotide insertions between the -35 and -10 ampC promoter sequences was the mechanism for the hyperproduction of AmpC beta-lactamase and resistance to oxyimino-cephalosporins. The failure of the two patients to respond to treatment with oxyimino-cephalosporins highlights the important role of such a resistance mechanism in the clinical setting.