Yusuke Koizumi

Emergence of antiretroviral therapy resistance-associated primary mutations among drug-naive HIV-1-infected individuals in rural western cameroon

Summary: The prevalence of antiretroviral therapy (ART) resistance-associated mutations among HIV-1 strains in western Cameroon was evaluated by genotypically analyzing strains isolated from drug-naive individuals. Proviral DNA was extracted from 54 blood samples and amplified by polymerase chain reaction of protease, reverse transcriptase, integrase, and envelope genes. At least 4 clones per sample were analyzed. Of 54 HIV-1 strains, 45 (83.3%) had a concordant subtype or circulating recombinant form (CRF) designation: 40 CRF02_AG, 2 subtype A1, 2 G, and 1 F2. The remaining 9 (16.7%) had a discordant subtype: 6 subtype A1/CRF02_AG, 2 D/CRF02, and 1 G/CRF02. Protease inhibitor-associated primary resistance mutations were found in 4 (7.4%) cases: M46L with full clones in 1 case, and M46I, M46L, and V82A as minor populations in 1 case each. Reverse transcriptase inhibitor-associated primary resistance mutations were found in 5 (9.8%) samples: Y188C in 2 cases, and L100I, M184V, and V75I in 1 case each, although all of these mutations were found as minor populations. This is one of the first reports of the emergence of primary ART resistance mutations among drug-naive, non-B subtype HIV-1-infected individuals in Cameroon. Follow-up studies should be conducted to assess whether these drug-resistant mutants found as minor populations might impact future ART.

Evaluation of VZV‐specific cell‐mediated immunity in adults infected with HIV‐1 by using a simple IFN‐γ release assay

The development of herpes zoster is associated with reduced varicella zoster virus (VZV)‐specific cell‐mediated immune (CMI) reactions. In this study, VZV‐specific CMI reactions in 42 anti‐VZV‐IgG antibody‐positive adults infected with HIV‐1 were evaluated by measuring the IFN‐γ production levels in whole blood in response to stimulation with ultraviolet light‐inactivated live attenuated VZV vaccine. The median VZV‐specific IFN‐γ production level in all patients was 63 pg/ml. Antiretroviral therapy (ART)‐naïve patients with an AIDS‐defining illness (HIV classification category C) had significantly lower IFN‐γ production than ART‐naïve patients in categories A and B and patients receiving ART (P = 0.0194 and P = 0.0046, respectively). IFN‐γ production increased significantly in patients within 1 month of the onset of recurrent VZV disease and at more than 1 year from onset, compared with patients who had never had recurrent VZV disease (P = 0.0396 and P = 0.0484, respectively). In multivariate analyses, category C and history of recurrent VZV disease were significant factors affecting IFN‐γ production. Levels of IFN‐γ were measured before and after ART in seven ART‐naïve patients with no history of recurrent VZV disease, and no significant changes were observed. The results indicate that VZV‐specific CMI reactions were reduced in patients with an AIDS‐defining illness and enhanced in patients with a history of recurrent VZV disease, but not enhanced by ART alone. Vaccination may be necessary to inhibit the development of herpes zoster in patients receiving ART; this IFN‐γ releasing assay is one useful method for evaluating VZV‐specific CMI reactions in clinical settings. J. Med. Virol. 85:1313–1320, 2013.

Cerebral Syphilitic Gumma Can Arise Within Months of Reinfection: A Case of Histologically Proven Treponema pallidum Strain Type 14b/f Infection With Human Immunodeficiency Virus Positivity

A 44-year-old man with human immunodeficiency virus positivity developed cerebral gumma 6 months after appropriate therapy for secondary syphilis. It was surgically resected and histologically, Treponema pallidum (14b/f, a relatively rare strain type) was proven. A complete set of modern techniques was performed to depict rare complication of this classic disease.

In vitro and in vivo Pharmacodynamics of Colistin and Aztreonam Alone and in Combination against Multidrug-Resistant Pseudomonas aeruginosa

Background: Reports of Pseudomonas aeruginosa with high antimicrobial resistance have steadily emerged, threatening the utility of a mainstay in antipseudomonal therapy. This study evaluated the antimicrobial activities of various combination therapies against P. aeruginosa with high antimicrobial resistance, including multidrug-resistant P. aeruginosa (MDRP) using an in vitro and in vivo study. Methods: We evaluated 24 combination therapies, including colistin, aztreonam, meropenem, ceftazidime, ciprofloxacin, amikacin, rifampicin, arbekacin and piperacillin against 15 MDRP isolates detected at Aichi Medical University Hospital with the break-point checkerboard method. Based on the results of the in vitro study, we evaluated antimicrobial activity against highly antimicrobial-resistant P. aeruginosa with an in vivo murine thigh infection model. Results: The combination regimens including colistin and aztreonam showed higher antimicrobial activity against the 15 MDRP isolates. In the in vivo study, the high-dose colistin monotherapy (16 mg/kg every 12 h) achieved greater log10 CFU changes than the normal-dose colistin regimen (8 mg/kg every 12 h) against 5 P. aeruginosa isolates, including 2 MDRP isolates (p < 0.05). Aztreonam monotherapy (400 mg every 8 h) yielded bacterial densities similar to untreated control mice for the MDRP isolate evaluated. The combination therapy with a higher dose of colistin had superior antimicrobial activity against 5 P. aeruginosa with colistin (MIC 0.5 μg/ml) and aztreonam (MIC ≥128 μg/ml) than colistin monotherapy. Conclusion: The data suggest that the combination treatment of colistin and aztreonam could be the most useful for treating highly resistant P. aeruginosa with a higher susceptibility to colistin, including MDRP infections.

A case of non-cirrhotic portal hypertension associated with anti- retroviral therapy in a Japanese patient with human immunodeficiency virus infection

The diagnosis of non-cirrhotic portal hypertension (NCPH), a rare but potentially life-threatening complication in human immunodeficiency virus (HIV)-positive individuals, often occurs only after the emergence of fatal manifestations such as bleeding of esophageal varices. We herein report a female Japanese HIV patient who developed NCPH approximately 4 years after discontinuation of 65 months of didanosine (ddI) administration. The patient presented with severe ascites, bloody bowel discharge, extreme abdominal swelling, and symptoms of portal hypertension but no sign of liver cirrhosis. Examination revealed esophageal varices, oozing-like bleeding from a wide part of the colon, significant atrophy of the right lobe of the liver, and arterio-portal shunting and recanalization from the left medial segment branch of the portal vein to a paraumbilical vein, but no visible obstruction of the main trunk of the portal vein. Treatment for esophageal varices consisted of coagulation therapy with argon plasma after enforcement by endoscopic sclerotherapy and oral administration of β-blockers for elevated portal blood pressure. The patient has not experienced gastrointestinal bleeding in the approximately 5 years since the diagnosis of NCPH. Reviewing this case suggests the importance of suspecting NCPH in HIV patients with liver dysfunction of unknown etiology with a history of ddI and other purine analogs use, as well as the importance of controlling portal hypertension and esophageal varices in the treatment of NCPH.

Considerations about the Use of a Loading Dose of Daptomycin in a Neutropenic Murine Thigh Infection Model with Methicillin-Resistant Staphylococcus aureus Infection

Previous clinical studies have showed the clinical benefits of the initiation of treatment with a daptomycin (DAP) loading dose, but only a few studies have evaluated its antimicrobial benefits. We evaluated the efficacy of a DAP loading dose against methicillin-resistant Staphylococcus aureus (MRSA) infections in a neutropenic murine thigh infection model. Three MRSA isolates (DAP MIC: 0.5, 1, and 2 mg/L) were tested. Four DAP regimens simulating human concentration-time profiles, i.e., (i) day 1: 8 mg/kg and day 2: 6 mg/kg, (ii) days 1 and 2: 6 mg/kg/day, (iii) day 1: 8 mg/kg and day 2: 4 mg/kg, and (iv) days 1 and 2: 4 mg/kg/day, were administered to the mice. Efficacy was calculated as the change in bacterial density. DAP loading-dose regimen iii showed greater antimicrobial activity against MRSA with MIC 1 mg/L than nonloading regimen iv (-3.10 ± 0.63 vs. -0.71 ± 0.34 log10 CFU; p < 0.01). Loading-dose regimen iii achieved greater log10 CFU changes than nonloading regimen ii, while the total DAP dose for 2 days was the same (-3.10 ± 0.63 vs. -1.46 ± 0.48 log10 CFU; p < 0.05). DAP loading-dose regimen iii showed enhanced antimicrobial activity against MRSA with DAP MIC 0.5 mg/L when compared with nonloading regimen iv. However, loading-dose regimens i and iii did not reduce bacterial density for MRSA with DAP MIC 2 mg/L. Our data suggest that a DAP loading-dose regimen would be an advantageous procedure for patients infected with MRSA with DAP MIC ≤1 mg/L.