One dose versus three weekly doses of benzathine penicillin G for patients co-infected with HIV and early syphilis: a multicenter, prospective observational study.

BACKGROUND: One dose of benzathine penicillin G (BPG) has been recommended for HIV-infected patients with early syphilis (primary, secondary, and early latent syphilis) in the sexually transmitted diseases treatment guidelines, but clinical data to support such a recommendation are limited. METHODS: We prospectively observed the serological response to 1 or 3 weekly doses of BPG in HIV-infected adults who sought treatment of early syphilis at 8 hospitals around Taiwan. Rapid plasma reagin (RPR) titers were followed every 3-6 months after treatment. The serological response was defined as a 4-fold or greater decline in RPR titers at 12 months of treatment. The missing values were treated by following the last-observed-carried-forward principle. We hypothesized that 1 dose was non-inferior to 3 weekly doses of BPG with the non-inferiority margin for the difference of serological response set to 10%. RESULTS: Between 2007 and 2012, 573 patients completed at least 12 months of follow-up: 295 (51.5%) receiving 1 dose of BPG (1-dose group) and 278 (48.5%) 3 doses (3-dose group). Overall, 198 patients (67.1%; 95% confidence interval [CI], 61.4-72.5%) in the 1-dose group achieved serological response at 12 months, as did 208 patients (74.8%; 95% CI, 69.3-79.8%) in the 3-dose group (one-sided 95% CI of the difference, 15.1%). In the multivariate analysis, secondary syphilis (adjusted odds ratio [AOR], 1.90; 95% CI 1.17-3.09), RPR titer ≥32 (AOR, 1.93; 95% CI, 1.38-2.69), and 3 doses of BPG (AOR, 1.68; 95% CI, 1.20-2.36) were independently associated with a serological response. The time to the first episode of treatment failure was 1184 (standard deviation [SD], 70.5) and 1436 (SD, 80.0) days for 1- and 3-dose group, respectively. CONCLUSIONS: Single-dose BPG resulted in a higher serological failure rate and shorter time to treatment failure than 3 weekly doses of BPG in the treatment of early syphilis in HIV-infected patients.

Seroprevalence of hepatitis B virus among adults at high risk for HIV transmission two decades after implementation of nationwide hepatitis B virus vaccination program in Taiwan.

BACKGROUND: Seroprevalence of hepatitis B virus (HBV) after implementation of universal neonatal HBV vaccination and catch-up vaccination programs remains rarely investigated among the adults who were born in the vaccination era (in or after 1986) and engaged in high-risk sexual behaviors. MATERIALS AND METHODS: Between 2006 and 2012, we determined HBV surface antigen ([HBsAg), anti-HBs, and HBV core antibody (anti-HBc), hepatitis C virus antibody (anti-HCV) and rapid plasma reagin titers among HIV-infected men who have sex with men (MSM) born during 1984-1985 (Group I: 244 persons) and those born in or after 1986 (Group II: 523), and HIV-uninfected MSM (Group III: 377) and heterosexuals (Group IV: 217) born in or after 1986. Prevalence and incidence of HBV infection were estimated and multivariate analysis was performed to identify factors associated with HBsAg positivity. RESULTS: Compared with Group I, Groups II-IV had a significantly lower prevalence of HBsAg positivity (7.8% vs 3.7%, 2.4%, and 3.2%, respectively); and the prevalence of anti-HBc positivity was also lower for Groups III and IV (30.3% vs. 19.6%, and 18.0%, respectively), but no difference was observed between Groups I and II (30.3% vs. 26.3%). In multivariate analysis, HBsAg positivity was significantly associated with syphilis (adjusted odds ratio, 2.990; 95% confidence interval, 1.502-5.953) and anti-HCV positivity (adjusted odds ratio, 3.402; 95% confidence interval, 1.091-10.614). In subjects of Group II with all-negative HBV markers at baseline, the incidence rate of HBsAg seroconversion was 0.486 episodes per 100 person-years; and for those who received combination antiretroviral therapy containing lamivudine and/or tenofovir, none developed HBsAg seroconversion during the follow-up. CONCLUSIONS: Among the adults who were born in or after 1986 and engaged in high-risk sexual behaviors in Taiwan, neonatal HBV vaccination and catch-up vaccination programs conferred long-term protection against HBsAg seroconversion and HBsAg positivity was associated with syphilis and anti-HCV positivity.

Evaluation of macrolide resistance and enhanced molecular typing of Treponema pallidum in patients with syphilis in Taiwan: a prospective multicenter study.

Studies of macrolide resistance mutations and molecular typing using the newly proposed enhanced typing system for Treponema pallidum isolates obtained from HIV-infected patients in the Asia-Pacific region are scarce. Between September 2009 and December 2011, we conducted a survey to detect T. pallidum using a PCR assay using clinical specimens from patients with syphilis at six major designated hospitals for HIV care in Taiwan. The T. pallidum strains were genotyped by following the enhanced molecular typing methodology, which analyzed the number of 60-bp repeats in the acidic repeat protein (arp) gene, T. pallidum repeat (tpr) polymorphism, and the sequence of base pairs 131 to 215 in the tp0548 open reading frame of T. pallidum. Detection of A2058G and A2059G point mutations in the T. pallidum 23S rRNA was performed with the use of restriction fragment length polymorphism (RFLP). During the 2-year study period, 211 clinical specimens were obtained from 136 patients with syphilis. T. pallidum DNA was isolated from 105 (49.8%) of the specimens, with swab specimens obtained from chancres having the highest yield rate (63.2%), followed by plasma (49.4%), serum (35.7%), and cerebrospinal fluid or vitreous fluid (18.2%) specimens. Among the 40 fully typed specimens, 11 subtypes of T. pallidum were identified. Subtype 14f/f (18 isolates) was the most common isolates, followed by 14f/c (3), 14b/c (3), and 14k/f (3). Among the isolates examined for macrolide resistance, none had the A2058G or A2059G mutation. In conclusion, we found that type 14 f/f was the most common T. pallidum strain in this multicenter study on syphilis in Taiwan and that none of the isolates exhibited 23S rRNA mutations causing resistance to macrolides.

Bacteremia caused by extended-spectrum-ß-lactamase-producing Escherichia coli sequence type ST131 and non-ST131 clones: comparison of demographic data, clinical features, and mortality.

Escherichia coli producing the highly virulent, multidrug-resistant, CTX-M-15 extended-spectrum ß-lactamase (ESBL), sequence type 131 (ST131), has emerged on three continents since the late 2000s. We described the molecular epidemiology, clinical features, and outcome of ESBL-producing E. coli bacteremia in Taiwan from 2005 to 2010. This study aims to determine whether the risk factors, clinical features, and outcomes of the ST131 isolate differ from those of non-ST131 isolates. From 2005 to 2010, we collected 122 nonduplicated, consecutive, ESBL-producing E. coli isolates from bloodstream infections in a 1,200-bed hospital in Taiwan. Isolates were characterized using multilocus sequence typing. Demographic data, clinical features, and outcomes were collected from medical chart records. Thirty-six (29.5%) patients with bacteremia with ESBL-producing E. coli ST131 were identified. Patients with clone ST131 were more likely to have secondary bacteremia and noncatheterized urinary tract infections (P < 0.05). Secondary bacteremia (odds ratio [OR], 5.05; 95% confidence interval [CI], 1.08 to 23.56) and urinary catheter nonuse (OR, 3.77; 95% CI, 1.17 to 12.18) were independent risk factors for the ST131 clone after adjustment. Mortality rates at day 28 were similar in ST131 and non-ST131 populations. Independent risk factors predicting mortality at day 28 included malignancy, shock, and hospital-acquired bacteremia. In ESBL-producing E. coli bloodstream infections, the ST131 clone was not associated with health-care-associated risk factors, such as urinary catheter use or antibiotic exposure. Although highly virulent and multidrug resistant, the ST131 clone was not associated with higher mortality than non-ST131 clones.

Sphingomonas paucimobilis bacteremia in humans: 16 case reports and a literature review.

BACKGROUND/PURPOSE: Sphingomonas paucimobilis is a glucose-nonfermenting Gram-negative bacillus that is widely distributed in both natural environment and hospitals. Various infections in humans have been reported, but most have been limited to sporadic case reports. The aim of this study was to describe the clinical characteristics and manifestations of S. paucimobilis bacteremia. We also reviewed the literature on S. paucimobilis bacteremia. METHODS: Cases of S. paucimobilis bacteremia were identified retrospectively at a university-affiliated hospital in Taiwan. In addition, relevant case reports were identified through PubMed and reviewed. RESULTS: From April 2004 to April 2008, 42 cases of S. paucimobilis bacteremia were identified in this study. Among them, 16 cases were identified from E-Da hospital, Kaohsiung, Taiwan and 26 cases from the literature review. The median age of patients was 48.5 years and 57.1% were male. The most common comorbidities included malignancy (57.1%), immunosuppressant use (40.5%), and diabetic mellitus (11.9%). Hospital-acquired bacteremia accounted for 69.0% of infections. Primary bacteremia and catheter-related bloodstream infection were found in 35.7% and 33.3% respectively. The most effective antibiotics were fluoroquinolones, carbapenems, and beta-lactam/beta-lactamase inhibitor combinations. All 42 patients survived the S. paucimobilis bacteremic episodes, but three patients experienced septic shock. CONCLUSION: S. paucimobilis can cause infections in healthy as well as immunocompromised individuals. Although it is an organism of low clinical virulence, infection caused by S. paucimobilis can lead to septic shock. Further clinical research is required to characterize this infection.

Risk factors of isolated antibody against core antigen of hepatitis B virus: association with HIV infection and age but not hepatitis C virus infection.

BACKGROUND: Isolated antibody to hepatitis B core antigen (anti-HBc) is defined as seropositivity for anti-HBc in the absence of hepatitis B surface antigen (HBsAg) and antibody to HBsAg (anti-HBs). It is commonly found in HIV-infected persons or hepatitis C virus (HCV)-infected persons, but the risk factors for isolated anti-HBc remain uncertain, especially in regions that are hyperendemic for hepatitis B virus (HBV) infection. METHODS: This cross-sectional study included a cohort of 955 nonhemophiliac, HIV-infected patients, diagnosed between 1988 and 2009, and 643 HIV-uninfected injection drug users (IDUs) attending the methadone clinic between August 2007 and May 2009, with available HBV serological data. The medical records were reviewed to identify the risk factors associated with seropositivity of isolated anti-HBc. RESULTS: The overall seroprevalence of isolated anti-HBc was 12.1% (193 of 1598), in which occult HBV infection accounted for 1.6% (3 of 185) and the majority (91.2 %, 176 of 193) had low titers of anti-HBs (3.6 +/- 2.9 IU/L). Subjects with isolated anti-HBc were significantly older (40.7 +/- 9.3 versus 36.9 +/- 8.0, respectively, P < 0.0001). There was a significantly increasing trend in the prevalence of isolated anti-HBc with age, from 4.0% in those younger than 30 years to 22.5% after 50 years of age (test for trend, P < 0.0001). A significantly higher prevalence of isolated anti-HBc was observed in HIV-infected subjects [14.0% (134 of 955) versus 9.2% (59 of 643), adjusted odds ratio, 1.64; P < 0.01], but not in those with HCV infection (P = 0.18). CONCLUSIONS: Isolated anti-HBc seropositivity was significantly associated with HIV infection, and older age. HCV infection was not associated with isolated anti-HBc in a country hyperendemic with HBV infection, even in populations with a high prevalence of HCV infection. The majority was not attributable to occult HBV infection, but rather, low level of anti-HBs, suggesting that HBV vaccination may not be required.

Endometriosis presenting as bloody ascites and shock.

Endometriosis is defined as the presence of ectopic foci of endometrial tissue outside the uterine cavity. Many patients are asymptomatic, but others present protean symptoms, including headache, cyclic hemoptysis, pleural effusion, and ascites depending on the endometrial implantation sites. Although massive ascites has been reported as a manifestation of endometriosis, hypovolemic shock is unusual. We report a case of endometriosis presenting as shock and bloody ascites to show that endometriosis can result in acute abdomen with shock. A 29-year-old female presented to our Emergency Department (ED) complaining of light-headedness and palpitations. Examination suggested hypovolemic shock. Ultrasonography revealed massive ascites and paracentesis showed bloody ascites. Exploratory laparoscopy showed endometriosis over the left broad ligament. After fluid resuscitation and electrocauterization of the endometriosis, the patient's condition stabilized, and she was discharged 5 days after admission. This case is presented to raise awareness that endometriosis can present with hypovolemic shock.

Epidemiology of acute q Fever, scrub typhus, and murine typhus, and identification of their clinical characteristics compared to patients with acute febrile illness in southern taiwan.

BACKGROUND/PURPOSE: In Taiwan, acute Q fever, scrub typhus, and murine typhus (QSM diseases) are the most common rickettsioses, but their epidemiology and clinical characteristics have not been clarified. Diagnosis of these three diseases based on clinical manifestations is difficult, and most of their reported characteristics are identified by describing the predominant manifestations, without being compared with other diseases. METHODS: Serological tests for QSM diseases were examined simultaneously in patients suspected of the three diseases, regardless of which one was suspected. Clinical manifestations were recorded retrospectively from their charts. The characteristics of QSM diseases were identified by comparison with patients who had non-QSM diseases. RESULTS: From April 2004 to April 2007, a total of 226 cases of suspected QSM diseases were included. One hundred (44.2%) cases were serologically confirmed as QSM diseases (68 acute Q fever, 23 scrub typhus, and 9 murine typhus), and 126 (55.8%) cases were non-QSM diseases. Only 33 cases (33.0%) of QSM diseases were initially suspected at the time of hospital visit, whereas 54 cases (42.9%) of non-QSM diseases were incorrectly suspected as QSM diseases. Cases of Q fever and scrub typhus were distributed over plain and mountain areas, respectively. By multivariate analysis, relative bradycardia (OR [95% CI], 2.885 [1.3-6.4]; p = 0.009), radiographic hepatomegaly (OR [95% CI], 4.454 [1.6-12.3]; p = 0.004), and elevated serum aminotransferases (OR [95% CI], 5.218 [1.2-23.1]; p = 0.029) were independent characteristics for QSM diseases, and leukocytosis (OR [95% CI], 0.167 [0.052-0.534]; p = 0.003) was negative for the diagnosis of QSM diseases. CONCLUSION: In southern Taiwan, acute Q fever is the most common rickettsiosis. QSM diseases should be suspected in febrile patients who present with relative bradycardia, hepatomegaly, and elevated serum aminotransferases, but without leukocytosis.

Salmonella infection after surgery of small intestine foreign bodies.

OBJECTIVE: To report the first case of Salmonella enterica serotype choleraesuis infection after surgery for small intestine foreign bodies. CLINICAL PRESENTATION AND INTERVENTION: A 52-year-old woman presented to our hospital with the chief complaint of left abdominal pain for 1 day. The plain kidney-ureter-bladder film and abdominal computed tomography scan showed foreign bodies in the peritoneum. Metallic foreign bodies in the jejunum were found during surgery. Following surgery, the patient developed fever, and blood culture yielded Salmonella enterica serotype choleraesuis. The patient recovered smoothly after antibiotic therapy. CONCLUSION: Salmonella enterica serotype choleraesuis is a highly invasive serotype of nontyphodial Salmonella. In addition to gastroenteritis, bacteremia, or extraintestinal localized infections, physicians should know that it could complicate intestinal surgery.

Pharmacokinetics and safety of multiple intravenous doses of daptomycin in a Taiwanese adult population.

BACKGROUND: The pharmacokinetics (PK) and safety of daptomycin have not yet been studied in an adult Taiwanese population. METHODS: A total of 13 healthy adult Taiwanese subjects (7 males and 6 females) were enrolled to receive a 5-day course of multiple intravenous daptomycin infusions at a dose of 4 mg/kg every 24 h. Both single-dose and steady-state serum PK were assessed. RESULTS: PK evaluation showed no relevant accumulation of daptomycin based on the steady-state PK, which could be predicted from the single-dose PK. No gender effect on daptomycin, for either single- or multiple-dose PK, was observed. About 60% of the infused daptomycin was eliminated by the renal system in an unchanged form. Protein binding of daptomycin was about 93.92%. The PK parameters in healthy Taiwanese subjects were similar to those reported in healthy Caucasian subjects. No serious adverse events (AE) or deaths occurred during the study. The most frequently reported AE was leukopenia (3/19, 15.8%), followed by amblyopia (2/19, 10.5%). These AEs were considered to be mild-to-moderate in severity and resolved spontaneously. CONCLUSION: This study demonstrated similarities between Taiwanese and Caucasian healthy subjects in the PK profiles of daptomycin, and thus the dosage regimen used in Caucasian subjects could be applied to Taiwanese.

The difference in clinical characteristics between acute Q fever and scrub typhus in southern Taiwan.

OBJECTIVE: To identify the differences in clinical characteristics between acute Q fever and scrub typhus in southern Taiwan. METHODS: A prospective observational study was conducted in which serological tests for acute Q fever and scrub typhus were performed simultaneously regardless of which disease was suspected clinically. From April 2004 to December 2007, 80 and 40 cases of serologically confirmed acute Q fever and scrub typhus, respectively, were identified and included in the study for comparison. RESULTS: By univariate analysis, being male (p<0.001) and having an alanine aminotransferase (ALT) >88U/l (p=0.015) were more common in acute Q fever, whereas residence or travel in a mountainous region or offshore island of Taiwan (p<0.001), skin rash (p<0.001), eschar (p<0.001), lymphadenopathy (p=0.04), leukocytosis (p=0.002), and pulmonary involvement on chest X-ray (p=0.003) were more common in scrub typhus. In the multivariate analysis, being male (odds ratio (OR) 10.883, 95% confidence interval (CI) 2.079-56.441, p=0.005) was an independent characteristic of acute Q fever, while residence or travel in a mountainous region or offshore island (OR 0.073, 95% CI 0.019-0.275, p<0.001) and skin rash (OR 0.152, 95% CI 0.024-0.945, p=0.043) were independent characteristics of scrub typhus. The response to doxycycline treatment was not different. CONCLUSIONS: In southern Taiwan, sex, area of residence, travel history, and physical examination are important in the differentiation of acute Q fever from scrub typhus.

Clinical characteristics of acute Q fever, scrub typhus, and murine typhus with delayed defervescence despite doxycycline treatment.

Doxycycline is the recommended antibiotic for acute Q fever, scrub typhus, and murine typhus and defervescence often occurs within 3 days of treatment. Patients with delayed defervescence (> 3 days) are troublesome for clinicians. To investigate the characteristics of such patients, 18 and 88 cases with and without delayed defervescence, respectively, were studied. By univariate analysis, absence of headache (P = 0.004), jaundice (P = 0.030), icteric sclera (P = 0.030), relative bradycardia (P = 0.003), and pulmonary involvement on chest x-ray (P = 0.028) were significant findings in patients with delayed defervescence. By multivariate analysis, absence of headache (odds ratio [OR] = 8.310; 95% confidence interval [CI] = 1.990-34.706, P = 0.004), jaundice (OR = 6.242; 95% CI = 1.374-28.365, P = 0.018), and relative bradycardia (OR = 10.449; 95% CI = 2.137-51.088, P = 0.004) were the independent characteristics of patients with delayed defervescence. In treating acute Q fever, scrub typhus, and murine typhus with doxycycline, clinicians should be aware that delayed defervescence may occur in patients presenting with jaundice, relative bradycardia, and absence of headache.

Non-septicemic melioidosis presenting as cardiac tamponade.

Melioidosis is endemic in Taiwan. It is caused by infection with Burkholderia pseudomallei. A prolonged course of oral eradication therapy to avoid relapse after an intensive intravenous therapy is recommended to treat melioidosis. Melioidosis with cardiac involvement is rare and is often combined with septicemia, for which the mortality rate is 20-60%. The initial clinical presentations of melioidosis mimic Mycobacterium tuberculosis infection, which is the most common etiology of bacterial pericarditis in Taiwan. We present a case of non-septicemic melioidosis that presented as non-suppurative cardiac tamponade and left subcarinal lymphadenopathy. Underlying diseases included hepatitis B-related liver cirrhosis and hepatocellular carcinoma. The patient was successfully treated with 2 weeks of intravenous ceftazidime and 12 weeks of oral doxycycline, trimethoprim-sulfamethoxazole, and amoxicillin/clavulanate. Melioidosis-related pericarditis should be considered in the differential diagnoses of bacterial pericarditis in Taiwan.

Myoclonic jerks due to acute bromovalerylurea intoxication.

BACKGROUND: Bromides are still sold as sedatives, antitussives, and anticonvulsants in many countries. Bromovalerylurea is a bromide-containing sedative-hypnotic that is occasionally combined with non-steroidal anti-inflammatory drugs in over-the-counter products. Chronic intake of excessive bromovalerylurea can produce bromide intoxication, but acute bromovalerylurea intoxication presenting with myoclonic jerks has never been described. CASE REPORT: A 23-year-old woman was brought to our emergency department with unusual drowsiness. Her physical examination was normal except for frequent myoclonic jerks in all extremities that could be triggered by moving the patient or by noxious stimuli. Initial blood tests results were normal; the serum bromide concentration was 81.0 mg/L (reference <10 mg/L). Treatment with intravenous normal saline and furosemide resulted in gradual improvement in her drowsiness and myoclonic jerks. By the second hospital day, she was normal. A brain magnetic resonance imaging (MRI) was normal. At a 2-month follow-up visit, the patient had no neurological sequelae. DISCUSSION: Chronic bromide intoxication caused by long-term abuse of bromovalerylurea may present as psychiatric or neurologic abnormalities. Our case of acute bromovalerylurea intoxication presented with severe myoclonic jerks and lethargy. The serum bromide concentration was similar to the reported concentrations in acute bromide intoxications. Treatment with normal saline and diuretics results in increased clearance of bromide and an improvement in clinical effects. CONCLUSION: Myoclonic jerks may be one of the major presentations of acute bromovalerylurea intoxication. Physicians should consider bromide intoxication in the differential diagnosis of the causes of myoclonic jerks.

Seroprevalence of viral hepatitis and infectious complications among human immunodeficiency virus-infected injection drug users at a referral hospital.

BACKGROUND AND PURPOSE: The seroprevalence of viral hepatitis and spectrum of infectious complications among human immunodeficiency virus (HIV)-infected injection drug users (IDUs) remains unclear in Taiwan, although there has been a significant increase in the prevalence of HIV infection among IDUs in the last 2 to 3 years. METHODS: The medical records of HIV-infected IDUs who sought medical care at a referral hospital for HIV care from June 1994 to December 2006 were retrospectively reviewed. A standardized case record form was used to collect demographic, clinical, laboratory and microbiologic data. RESULTS: During the 12-year study period, a total of 102 HIV-infected IDUs with a median age of 39.5 years (range, 19 to 73 years) sought HIV care at the referral hospital. The male-to-female case ratio was 6 and males were significantly older than females (39.5 vs 28 years, p<0.001). The overall median CD4+ cell count and plasma HIV RNA load by reverse transcriptase-polymerase chain reaction at enrollment were 374 cells/microL and 4.45 log(10) copies/mL, respectively. The CD4+ cell count of HIV-infected IDUs enrolled after year 2003 was significantly higher than those enrolled before 2003 (438 vs 23 cells/microL, p<0.001). The seroprevalence of hepatitis C virus (86.6% overall) increased over time, while that of hepatitis B virus decreased in the patients born after 1984, when nationwide hepatitis B vaccination was started in Taiwan. Gram-positive bacteria were causative for 69.7% of the 33 bacteremic episodes, and Staphylococcus aureus was the leading pathogen (16 episodes), with methicillin-sensitive S. aureus accounting for 11 bacteremic episodes (33.3%). The most common bacterial infection was infective endocarditis. Tuberculosis occurred more frequently in men, and extrapulmonary tuberculosis was more common than pulmonary tuberculosis and was associated with a lower CD4+ count. CONCLUSIONS: Bacteremia, infective endocarditis and tuberculosis were the three most common patterns of infection among HIV-infected IDUs who sought medical care at a referral hospital; and methicillin-sensitive S. aureus was the most common etiology of bacteremia. The high seroprevalence of hepatitis B and C and subsequent hepatic complications may present a future challenge to the health care system.

Extremely high prevalence and genetic diversity of hepatitis C virus infection among HIV-infected injection drug users in Taiwan.

BACKGROUND: An outbreak of human immunodeficiency virus (HIV) type 1 infection among injection drug users (IDUs) occurred in Taiwan, and thereafter, injection drug use became the most frequent risk factor for HIV infection in Taiwan. We sought to study the prevalence of and genotypes causing hepatitis C virus (HCV) infection among HIV-infected IDUs in Taiwan. METHODS: A multicenter, longitudinal cohort study of 990 HIV-infected IDUs was conducted from 1993 through 2006. Blood samples were collected and analyzed for the presence of antibody to HCV and to determine the genotype of HCV. RESULTS: The overall prevalence of HCV infection among HIV-infected IDUs was 96.6%. The annual prevalence increased from 65.5% before 2002 to 98.6% in 2006. The main circulating HCV genotypes were 1a (accounting for 29.2% of samples), 6a (23.5%), and 3a (20.2%), whereas 1b, the most predominant genotype circulating in the general population in Taiwan, accounted for only 13.2% of samples. Genotypes 2b (accounting for 6.6% of samples), 6k (2.9%), 2a (1.6%), 6g (1.6%), and 3b (1.2%) were present in only a few IDUs. Multivariate logistic regression analysis revealed that duration of injection drug use and a travel history to China or Southeast Asia were significantly associated with infection due to HCV genotypes 1a, 3, and 6. CONCLUSIONS: Our study demonstrated a high prevalence of HCV infection among HIV-infected IDUs in Taiwan, with a predominance of infection due to genotypes 1a, 6a, and 3a, as a result of the impact of IDUs' behavior and their drug trafficking route. Our study revealed that HCV infection in IDUs originated from a geographically large transmission network that was mainly distinct from that associated with other HCV-infected individuals; this transmission network has also been documented in association with HIV infection in IDUs.