Molecular docking and simulation of the interaction of sulbactam with Acinetobacter baumannii BaeSR and AdeSR.

Acinetobacter baumannii infections are associated with a high mortality rate. Sulbactam, a beta-lactamase inhibitor, is commonly used to treat A. baumannii infections, but its underlying mechanisms are unclear. Two-component regulatory systems (TCSs) are important for bacterial adaptability and response ability. In this study, we focused on two TCSs, namely AdeSR and BaeSR, and identified a protein highly similar to the dimerization and histidine phosphotransfer (DHp) and catalytic ATP-binding (CA) domains of the TCSs by using Swiss-Model. Sulbactam and ß-lactamase inhibitors, which are structurally similar to sulbactam, were docked with the selected sequence 4JAS using the simulation tools SwissDock and ArgusLab. Analysis with both these analytical tools showed that sulbactam can react on the active sites of 4JAS at a relatively steady level (ΔG -7 to -10 kcal/mol). Sulbactam likely interacts with the active sites of BaeSR and AdeSR, and owing to its smaller size and ability to form ionic bonds with Mg2+, it may potentially compete with ATP/ADP in BaeSR and AdeSR and consequently interfere with A. baumannii multiplication. This is the first study to investigate the association between sulbactam and TCSs in A. baumannii using molecular docking and simulation analyses.

Sulbactam-enhanced cytotoxicity of doxorubicin in breast cancer cells.

BACKGROUND: Multidrug resistance (MDR) is a major obstacle in breast cancer treatment. The predominant mechanism underlying MDR is an increase in the activity of adenosine triphosphate (ATP)-dependent drug efflux transporters. Sulbactam, a ß-lactamase inhibitor, is generally combined with ß-lactam antibiotics for treating bacterial infections. However, sulbactam alone can be used to treat Acinetobacter baumannii infections because it inhibits the expression of ATP-binding cassette (ABC) transporter proteins. This is the first study to report the effects of sulbactam on mammalian cells. METHODS: We used the breast cancer cell lines as a model system to determine whether sulbactam affects cancer cells. The cell viabilities in the present of doxorubicin with or without sulbactam were measured by MTT assay. Protein identities and the changes in protein expression levels in the cells after sulbactam and doxorubicin treatment were determined using LC-MS/MS. Real-time reverse transcription polymerase chain reaction (real-time RT-PCR) was used to analyze the change in mRNA expression levels of ABC transporters after treatment of doxorubicin with or without sulbactam. The efflux of doxorubicin was measures by the doxorubicin efflux assay. RESULTS: MTT assay revealed that sulbactam enhanced the cytotoxicity of doxorubicin in breast cancer cells. The results of proteomics showed that ABC transporter proteins and proteins associated with the process of transcription and initiation of translation were reduced. The mRNA expression levels of ABC transporters were also decreased when treated with doxorubicin and sulbactam. The doxorubicin efflux assay showed that sulbactam treatment inhibited doxorubicin efflux. CONCLUSIONS: The combination of sulbactam and doxorubicin enhances the cytotoxicity of doxorubicin in the breast cancer cells by inhibiting the expression of ABC transporter proteins and proteins associated with the process of transcription and initiation of translation, and blocking the efflux of doxorubicin. Co-treatment of doxorubicin and sulbactam can be used in breast cancer treatment to decrease the prescribed dose of doxorubicin to avoid the adverse effects of doxorubicin.

Contribution of Acinetobacter-derived cephalosporinase-30 to sulbactam resistance in Acinetobacter baumannii.

The sulbactam resistance rate in Acinetobacter baumannii has increased worldwide. Previous reports have shown that the ß-lactamase bla TEM-1 confers resistance to sulbactam in A. baumannii. The purpose of this study was to examine whether other ß-lactamases, including the Acinetobacter-derived cephalosporinase (ADC), OXA-23, OXA-24/72, and OXA-58 families, also contribute to sulbactam resistance in A. baumannii. The correlation between these ß-lactamases and the sulbactam minimal inhibitory concentration (MIC) was determined using A. baumannii clinical isolates from diverse clonality, which were collected in a nationwide surveillance program from 2002 to 2010 in Taiwan. A possible association between the genetic structure of ISAba1-bla ADC-30 and sulbactam resistance was observed because this genetic structure was detected in 97% of sulbactam-resistant strains compared with 10% of sulbactam-susceptible strains. Transformation of ISAba1-bla ADC-30 into susceptible strains increased the sulbactam MIC from 2 to 32 µg/ml, which required bla ADC-30 overexpression using an upstream promoter in ISAba1. Flow cytometry showed that ADC-30 production increased in response to sulbactam, ticarcillin, and ceftazidime treatment. This effect was regulated at the RNA level but not by an increase in the bla ADC-30 gene copy number as indicated by quantitative PCR. Purified ADC-30 decreased the inhibitory zone created by sulbactam or ceftazidime, similarly to TEM-1. In conclusion, ADC-30 overexpression conferred resistance to sulbactam in diverse clinical A. baumannii isolates.

Bactericidal effect of sulbactam against Acinetobacter baumannii ATCC 19606 studied by 2D-DIGE and mass spectrometry.

Acinetobacter baumannii has been associated with several severe hospital-acquired infections such as ventilator-associated pneumonia and meningitis. Sulbactam, a ß-lactamase inhibitor, is usually combined with ß-lactam antibiotics to treat infections. It has been found that sulbactam alone may be used to treat infections caused by A. baumannii, although the mechanism of the bactericidal effect remains unknown. In this study, proteomics was used to analyse protein intensity changes and to identify the proteins of A. baumannii following sulbactam treatment. In total, 54 proteins were found to exhibit significant changes in intensity. Proteins with reduced intensity included ATP-binding cassette (ABC) transporters as well as 30S and 50S ribosomal subunit proteins. These proteins are essential for nutrient import and protein synthesis and are vital for bacterial survival. The amplified proteins included glutamine synthetase, malic enzyme, RNA polymerase subunit α, and the molecular chaperones DnaK and GroEL, which function in metabolism, DNA and protein synthesis, and repair machinery. These amplified proteins were increased to rescue bacteria, however they could not overcome the effects of the reduced proteins and the bacteria were killed. This is the first report that the reduction of ABC transporters and 30S and 50S ribosomal subunit proteins plays an important role in the bactericidal effect of sulbactam against A. baumannii.

Seroprevalence and severity of 2009 pandemic influenza A H1N1 in Taiwan.

BACKGROUND: This study is to determine the seroprevalence of the pandemic influenza A H1N1 virus (pH1N1) in Taiwan before and after the 2009 pandemic, and to estimate the relative severity of pH1N1 infections among different age groups. METHODOLOGY/PRINCIPAL FINDINGS: A total of 1544 and 1558 random serum samples were collected from the general population in Taiwan in 2007 and 2010, respectively. Seropositivity was defined by a hemagglutination inhibition titer to pH1N1 (A/Taiwan/126/09) ≥1:40. The seropositivity rate of pH1N1 among the unvaccinated subjects and national surveillance data were used to compare the proportion of infections that led to severe diseases and fatalities among different age groups. The overall seroprevalence of pH1N1 was 0.91% (95% confidence interval [CI] 0.43-1.38) in 2007 and significantly increased to 29.9% (95% CI 27.6-32.2) in 2010 (p<0.0001), with the peak attack rate (55.4%) in 10-17 year-old adolescents, the lowest in elderly ≥65 years (14.1%). The overall attack rates were 20.6% (188/912) in unvaccinated subjects. Among the unvaccinated but infected populations, the estimated attack rates of severe cases per 100,000 infections were significantly higher in children aged 0-5 years (54.9 cases, odds ratio [OR] 4.23, 95% CI 3.04-5.90) and elderly ≥ 65 years (22.4 cases, OR 2.76, 95% CI 1.99-3.83) compared to adolescents aged 10-17 years (13.0 cases). The overall case-fatality rate was 0.98 per 100,000 infections without a significant difference in different age groups. CONCLUSIONS/SIGNIFICANCE: Pre-existing immunity against pH1N1 was rarely identified in Taiwanese at any age in 2007. Young children and elderly--the two most lower seroprotection groups showed the greatest vulnerability to clinical severity after the pH1N1 infections. These results imply that both age groups should have higher priority for immunization in the coming flu season.

Seroprevalence of chronic hepatitis B virus infection among taiwanese human immunodeficiency virus type 1-positive persons in the era of nationwide hepatitis B vaccination.

OBJECTIVES: We aimed to assess the impact of nationwide hepatitis B virus (HBV) vaccination program on the seroprevalence of HBV infection among human immunodeficiency virus (HIV)-positive persons in a country where most HBV exposure occurs during the perinatal period or in early childhood. METHODS: Data on HBV surface antigen (HBsAg), anti-HBV surface (anti-HBs), anti-HBV core (anti-HBc), and anti-hepatitis C virus (anti-HCV) antibody were retrospectively collected from 3,164 HIV-positive and 2,594 HIV-negative persons between 2004 and 2007. Comparisons of serological markers of HBV and HCV were made between HIV-positive and -negative adults born before and after the implementation of the HBV vaccination program in Taiwan in July 1984. RESULTS: Compared with HIV-negative persons, the adjusted odds ratio for HBsAg seropositivity was 1.100 (95% confidence interval, 0.921-1.315) among HIV-positive persons. Although the seroprevalence of anti-HCV antibody remained similar between HIV-positive persons born before and those born after 1984, the seroprevalence of HBsAg declined from 20.3 to 3.3% in HIV-positive persons (P<0.001) and from 15.5 to 8.5% in HIV-negative persons (P<0.001). Despite the high seroprevalence of anti-HCV antibody (97.1%) in HIV-positive injecting drug users (IDUs), there was no statistically significant difference in the seroprevalence of HBsAg (5.6% vs. 8.5%, P=0.75) or anti-HBc antibody (40.7% vs. 27.9%, P=0.14) between HIV-positive IDUs and HIV-negative persons who were born after 1984. CONCLUSIONS: Our study showed a significant decline of seroprevalence of HBV infection among both HIV-negative and -positive persons who were born in the era of the nationwide HBV vaccination in Taiwan.

Huge pelvic mass, cutaneous and vaginal fistulas, and bilateral hydronephrosis: a rare presentation of actinomycosis with a good response to conservative treatment and with long-term sequelae of renal atrophy and hydronephrosis.

OBJECTIVE: Actinomycosis with an extended pelvic abscess is an uncommon condition, which usually occurs coincident with the presence of an intrauterine contraceptive device (IUD) in the uterine cavity. The clinical picture of pelvic actinomycosis may vary between individuals, is often accompanied by complications, and is frequently misdiagnosed. Here, we report a case of pelvic actinomycosis, presenting as a huge pelvic mass and complicated by a vaginal fistula, a cutaneous fistula, and bilateral hydronephrosis, and we discuss the diagnosis and management of this patient. CASE REPORT: A 35-year-old woman was referred to our hospital with a huge pelvic complex mass and progressively worsening low abdominal pain. The tumor workup, which included a computed tomography (CT) scan, revealed an extended pelvic abscess and bilateral hydronephrosis. Both cutaneous and vaginal fistulas were also noted. Endometrial curettage and biopsies of the skin and vaginal lesions confirmed the diagnosis of actinomycosis. The patient underwent conservative treatment and recovered well, although the skin lesion only healed after 12 weeks of oral antibiotic treatment. At the 1-year follow-up, a CT scan showed sequelae including a mildly atrophic left kidney and left hydronephrosis. CONCLUSION: In patients presenting with a pelvic mass and an IUD in the uterine cavity, the diagnosis of actinomycosis should be seriously considered. A detailed workup, including a CT scan, endometrial curettage and biopsies where possible, should be performed before surgery. Once diagnosis has been confirmed, conservative medical treatment should be attempted before considering laparotomy, to reduce the risk of complications. Despite successful treatment with antibiotics, long-term sequelae such as hydronephrosis and renal atrophy are possible in cases of extended pelvic actinomycosis.

Brain abscess: clinical analysis of 53 cases.

Fifty-three cases of brain abscess were treated at Mackay Memorial Hospital from January 1991 through December 2001. The ages ranged from 2 weeks to 84 years, with a peak at 40 to 50 years (11/53, 21%). The male to female ratio was 1.8:1 (34 males, 19 females). The most common presenting symptoms were fever (30/53, 57%), headache (29/53, 55%), and changed mental status (24/53, 45%). The duration of symptoms before hospitalization ranged from several hours to 2 months. A shorter duration of symptoms was associated with poor outcome. The common predisposing factors were otic infection (10/53, 19%), penetrating head trauma and neurosurgery (10/53, 19%), and bacterial endocarditis (5/53, 9%). The leading underlying diseases were diabetes mellitus (12/53, 23%) and/or liver cirrhosis (6/53, 11%), and both were independently associated with increased risk of mortality. Computed tomographic scanning and magnetic resonance imaging facilitated early diagnosis and proper management. Surgical intervention was used together with antibiotics in 33 (62%) of 53 patients in whom the average abscesses diameter was 3.75 cm (range, 2-6 cm). The remaining 20 (38%) patients whose average abscesses diameter was 2.3 cm (range, 1-3.5 cm) were treated with antibiotics only. Culture of material drained from abscesses isolated 27 microorganisms from 19 (58%) of the 33 patients, 81% (22/27) of which were aerobic and 19% (5/27) anaerobic bacteria. The most common pathogen was alpha-hemolytic Streptococcus spp. (6/27, 22%). Most of the patients with Klebsiella pneumoniae isolated from brain abscess, cerebrospinal fluid, and blood cultures were diabetic. A high mortality rate (9/20, 45%) was found in patients with medical treatment. A high index of suspicion is needed for the early diagnosis of brain abscess, particularly in patients with predisposing factors. In this series, early diagnosis using computed tomography and/or magnetic resonance scanning, optimal timing of surgery, and appropriate use of antibiotics were associated with improved outcome.

Haemophilus aphrophilus brain abscess: a case report.

Haemophilus aphrophilus infection is rare, and the organism is infrequently implicated in serious infection. We report a case of a 61-year-old patient who experienced left hemiparesis with dizziness. Computed tomography of the brain demonstrated a lesion with ring enhancement in the right frontotemporal region. Craniotomy was performed, abscess was drained, and H. aphrophilus was isolated. Following the surgical procedure and further antibiotic treatment, the patient recovered completely.

Characteristics of Plesiomonas shigelloides infection in Taiwan.

From January 1999 through December 2000, a total of 111 cases of Plesiomonas shigelloides infections were diagnosed in a medical center of northern Taiwan. The patients ranged in age from 22 days to 72 years. One third (39/111, 35%) of the positive cultures were found in young children (<2 years old). There was no significant difference in the incidence between males (56/111, 50%) and females (55/111, 50%). The peak seasons for the disease were summer (45/111, 41%) and autumn (42/111, 38%). The major clinical presentations in children were diarrhea (66/69, 96%) and fever (38/69, 55%), whereas diarrhea (41/42, 98%) and abdominal pain (30/42, 71%) were the most common presentations in adults. Most adults with P. shigelloides infection visited the emergency room (38/42, 90%) and received empirical antimicrobials (37/42, 88%), whereas children were more likely to be treated as outpatients (53/69, 77%) and inpatients (27/69, 39%). One third (23/69, 33%) of pediatric patients had mixed enteric infection, and 74% (17/23) of them were younger than 2 years. Salmonella species (17/24, 71%), especially group B Salmonella (12/17, 71%), were the most common mixed enteric pathogen. The disease is usually mild and self-limited. Symptomatic management is adequate and antimicrobial therapy is seldom required.