In vitro Activity of Colistin in Combination with Tigecycline against Carbapenem-Resistant Acinetobacter baumannii Strains Isolated from Patients with Ventilator-Associated Pneumonia

OBJECTIVE

This study investigated the minimum inhibitory concentration (MIC) values and in vitro activity of colistin in combination with tigecycline against carbapenem-resistant Acinetobacter baumannii strains isolated from patients with ventilator-associated pneumonia (VAP) using the E-test method.

METHODS

A total of 40 A. baumannii strains, identified using the Phoenix Automated Microbiology System (Becton, Dickinson and Co., Franklin Lakes, NJ, USA) by conventional methods, were included in this study. Pulsed-field gel electrophoresis was performed to examine the clonal relationships between isolates. The carbapenem resistance of the strains to colistin and tigecycline was assessed using the E-test method (Liofilchem, Roseto Degli Abruzzi, Italy). The in vitro activity of colistin in combination with tigecycline was evaluated using the fractional inhibitor concentration (FIC) index.

RESULTS

While only 1 of 40 A. baumannii strains was determined to be colistin resistant, 6 were tigecycline resistant. The MIC50, MIC90, and MIC intervals of the A. baumannii strains were 0.19, 1.5, and 0.064‒4 μg/ml for colistin and 1, 8, and 0.094‒256 μg/ml for tigecycline, respectively. No synergistic effect was observed using the FIC index; 8 strains exhibited an indifferent effect and 32 exhibited an antagonist effect. Three of the six strains that were resistant to tigecycline were indifferent; the remaining three were antagonistic. The colistin-resistant strain also exhibited an antagonist effect.

CONCLUSION

In contrast to their synergistic effect against carbapenem-resistant A. baumannii isolates, colistin and tigecycline were highly antagonistic to carbapenem-resistant A. baumannii strains isolated from patients with VAP when the drugs were administered together. Therefore, alternative treatment options should be used during the treatment of VAP attributed to A. baumannii.

Meningitis following spinal anaesthesia in an obstetric patient

Meningitis following lumbar puncture and spinal anaesthesia is a rare but serious complication. A 19-year-old woman was administered spinal anaesthesia at another centre prior to a Caesarean section. The following day she experienced headaches. On the fourth day, she started vomiting and having convulsions, and became agitated. Meningitis was diagnosed based on a clinical examination and analysis of a lumbar puncture sample. After 21 days of treatment, she was discharged. Meningitis should be considered in the differential diagnosis of a patient presenting with headaches following spinal anaesthesia. The causes of meningitis following spinal anaesthesia are debated, and it is difficult to distinguish between aseptic and bacterial meningitis. It should be compulsory to wear a face mask while performing a dural puncture.

Silicon nanowire-silver indium selenide heterojunction photodiodes

Structural and optoelectronic properties of silicon (Si) nanowire-silver indium selenide (AgInSe2) thin film heterojunctions were investigated. The metal-assisted etching method was employed to fabricate vertically aligned Si nanowire arrays. Stoichiometric AgInSe2 films were then deposited onto the nanowires using co-sputtering and sequential selenization techniques. It was demonstrated that the three-dimensional interface between the Si nanowire arrays and the AgInSe2 thin film significantly improved the photosensitivity of the heterojunction diode compared to the planar reference. The improvements in device performance are discussed in terms of interface state density, reflective losses and surface recombination of the photogenerated carriers, especially in the high-energy region of the spectrum.

Identification and determination of antibiotic susceptibilities of Brucella strains isolated from patients in van, Turkey by conventional and molecular methods

PURPOSE

Brucellosis is a worldwide zoonotic disease and still constitutes a major public health problem. In this study, we aimed to identify biovars of Brucella strains isolated from clinical specimens taken from brucellosis patients from the Eastern Anatolia region as well determine the susceptibility of these isolates to tigecycline and azithromycin, drugs that may serve as alternatives to the conventional drugs used in the therapy.

MATERIALS AND METHODS

Seventy-five Brucella spp. isolates were included in the study. All strains were identified by both conventional and molecular methods. Brucella Multiplex PCR kit (FC-Biotech, Code: 0301, Turkey) and B. melitensis biovar typing PCR kit (FC-Biotech, Code: 0302, Turkey) were used for molecular typing. Antimicrobial susceptibilities of all strains were determined by E-tests.

RESULTS

By conventional biotyping, 73 strains were identified as B. melitensis biovar 3 and two strains as B. abortus biovar 3. Molecular typing results were compatible with conventional methods. The MIC50 and MIC90 values of doxycycline were 0.047 and 0.094; tigecycline 0.094 and 0.125; trimethoprim/sulfamethoxazole 0.064 and 0.19; ciprofloxacin 0.19 for both; streptomycin 0.75 and 1; rifampin 1 and 2 and azithromycin 4 and 8. According to the MIC values, doxycycline was found to be the most effective antibiotic, followed by tigecycline, trimethoprim-sulfamethoxazole and ciprofloxacin.

CONCLUSION

Currently recommended antibiotics for the treatment of brucellosis such as doxycycline, rifampin, streptomycin, trimethoprim-sulfamethoxazole and ciprofloxacin were found to be still effective. While our results showed that tigecycline can be used an alternative agent in the treatment of brucellosis, azithromycin has not been confirmed as an appropriate agent for the treatment.

Correlation between hippocampal volume and excessive daytime sleepiness in obstructive sleep apnea syndrome

BACKGROUND/AIM

The limbic system, specifically the hippocampus, plays a key role in controlling the sleep-wake cycle. Changes in these particular structures of the central nervous system have been suggested to be related to obstructive sleep apnea syndrome (OSAS). We hypothesized that reduced hippocampal volume is a risk factor for excessive daytime sleepiness (EDS) in OSAS.

PATIENTS AND METHODS

Twenty-two patients with newly diagnosed OSAS and 20 healthy controls were included in the present study. Polysomnography was performed for each participant to determine the presence of OSAS. EDS was defined based on the Epworth sleepiness scale (ESS) score, and patients were grouped as sleepy or non-sleepy according to this score. The hippocampal volume was calculated by MR volumetry using a manual tracing technique.

RESULTS

There was no significant difference between groups in demographic variables. The hippocampus was markedly smaller in the OSAS groups than in controls (p < 0.001 Hippocampal volume was negatively correlated with the ESS score (r = -0.631, p = 0.002).

CONCLUSIONS

Our findings suggest that EDS is associated with reduced hippocampal volume in OSAS.

The effects of L type calcium channels on the electroencephalogram recordings in WAG/RIJ rat model of absence epilepsy

BACKGROUND

Epilepsy is one of the most important central nervous system disorder and 1% of the total world population suffers from this disorder which require a chronic drug treatment. Most of the researchers suggested that excessive calcium entry into neurons is the main triggering event in the initiation of epileptic discharges but the role of L type calcium channels has not been clarified in absence epilepsy.

AIM

In this study, it is aimed to investigate the antiepileptic effects of nifedipine, an L type calcium channel blocker and BAY K8644, an L type calcium channel opener in a genetic model of absence epilepsy in WAG/Rij rats.

MATERIALS AND METHODS

Thirty two WAG/Rij rats were allocated into four groups; sham (only saline injected), only nifedipine (an L type calcium channel blocker) injected group (40 µg/2 µl; 60 µg/2 µl; 80 µg/2 µl), only BAY K8644 (1,4 Dihydro-2,6-dimethyl-5-nitro-4-trifluoromethyl- phenyl-3-pyridine carboxylic acid methyl ester) (L-type Ca2+-channel activator) injected group (40 µg/2 µl; 60 µg/2 µl; 80 µg/2 µl) and combination of their most effective doses BAY K8644 (60 µg/2 µl) after nifedipine (60 µg/2 µl) injected group. All agents were given by intracerebroventricular injection. The beta, alpha, theta and delta wave ratios of electroencephalogram recordings and the frequency and duration of SWDs (spike and wave discharges) were analyzed and compared between four groups.

RESULTS

Nifedipine increased the number and duration of spike wave discharges whereas BAY K8644 decreased both of them. When BAY K8644 was given after nifedipine, there was no significant difference with control group.

CONCLUSIONS

L type calcium channels play an activator role on spike wave discharges and have positive effects on the duration and frequency.

[Four malaria-import patterns: sporadic region]

Malaria, as it has been during history, is an important parasitic infectious health problem nowadays. In Turkey, the most common kind of malaria is Plasmodium vivax, and P. falciparum is rarely observed in import events. After eradication activities started in 1926, the number of cases dramatically decreased in our country. However, the number of import cases is increasing as a result of tourism, migration, and deficiency in the eradication program. In tropical and sub-tropical regions and in endemic regions of Turkey such as South-Eastern Anatolia and Çukurova, in every feverish phenomenon, malaria is the first disease to be considered. The purpose of the present study is to evaluate clinical epidemiological characteristics of the four import patterns in foreign studies.

Three-year review of bacteriological profile and antibiogram of burn wound isolates in Van, Turkey

The risk of infection in burns is well-known. In recent decades, the antimicrobial resistance of bacteria isolated from burn patients has increased. For this reason, a retrospective study was conducted at Van Training and Research Hospital to analyze the bacterial isolates from the wounds of patients admitted to the Burn Unit and to determine the susceptibility patterns of the commonly cultured organisms over a 3-year period, January 2009 to December 2011.A total of 250 microorganisms were isolated from burn wounds of 179 patients. Our results revealed that the most frequent isolate was Acinetobacter baumannii (23.6%), Pseudomonas aeruginosa (12%), Staphylococcus aureus (11.2%), Escherichia coli (10%) respectively. Multidrug-resistance has emerged as an important concern in our burn unit. Tigecycline, and colistin were found to be the most active drugs against Acinetobacter baumannii. Carbapenems and amikacin, were found to be the most active drugs against other gram negative bacteria. Vancomycin and linezolid were active against gram positive bacteria.Aggressive infection control measures should be applied to limit the emergence and spread of multidrug-resistant pathogens.

Management of Brucella endocarditis: results of the Gulhane study

Brucella endocarditis (BE) is a rare but life-threatening complication of human brucellosis. The aim of this study was to investigate the course of BE along with the therapeutic interrelations. A total of 53 patients with BE hospitalised in 19 health institutions between 2006 and 2011 were included in the Gulhane study. Diagnosis of brucellosis was established by either isolation of Brucella sp. or the presence of antibodies, and the definition of endocarditis was made according to Duke's criteria. There were four treatment groups: ceftriaxone combined with oral antibiotics (Group 1); aminoglycosides combined with oral antibiotics (Group 2); oral antibiotic combinations (Group 3); and aminoglycoside plus ceftriaxone combined with an oral antibiotic (Group 4). Involvement rates of the aortic, mitral and tricuspid valves were 49.1%, 43.4% and 5.7%, respectively. Thirty-two patients (60.4%) had an underlying cardiac valvular problem, including previous prosthetic valve replacement (n=18). Medical treatment was provided to 32 patients (60.4%), whilst concordant medical and surgical approaches were provided to 21 patients (39.6%). Mortality in Group 1 was 15% (3/20), whilst in Group 2 it was 5.3% (1/19). In Group 3, 25.0% (3/12) of the cases died, whereas none of the cases in Group 4 died. In conclusion, mortality increased 47-fold with pericardial effusion and 25-fold due to congestive heart failure that developed after BE. Although mortality was lower in the aminoglycoside-containing arm (Groups 2 and 4), statistical analysis could not be performed owing to the small number of patients.

Molecular characterization of hepatitis A virus isolated from acute infections in Turkey

BACKGROUND/AIMS

Hepatitis A virus is a global public health problem, especially in developing countries, and the most common cause of hepatitis in childhood. Hepatitis A virus is a single- stranded positive RNA virus subdivided to 6 genotypes (3 human,3 simian). The aim of this study was to determine the prevalent genotype in Turkey using sera of acute hepatitis A virus-infected patients from different geographical regions of the country.

MATERIALS AND METHODS

Sera of 137 patients with acute hepatitis A virus from different geographical regions were collected for phylogenetic analysis. The VP1-2A region of the hepatitis A virus genome was amplified by real-time-polymerase chain reaction in 76 patients where possible. Amplified polymerase chain reaction fragments were sequenced, and phylogenetic analysis was done together with other reference hepatitis A virus sequences obtained from GenBank database.

RESULTS

Sequencing and phylogenetic analysis of the VP1-2A junction of hepatitis A virus showed that the most prevalent genotype in Turkey is IB (100%). Comparison of Turkish isolates and reference sequences of genotype IB showed a similarity of 94.9%. The same comparison was done between Turkish isolates and reference hepatitis A virus genotype IB and HM175, and it was found that similarity between them ranged from 93.0-95.9%. When Turkish isolates were compared according to Mean Percentage Nucleotide Distance analysis, similarity ranged between 95.3%-100%.

CONCLUSIONS

Phylogenetic analysis pointed out that all Turkish isolates belong to genotype IB. Sequence analysis is a useful tool in revealing hepatitis A outbreaks, and allows us to detect and distinguish the presence of epidemic and small outbreaks.

Naturally Occurring Cutaneous Anthrax: Antibiotic Treatment and Outcome

<i>Objectives:</i> Cutaneous anthrax (CA) is the most common clinical presentation in human anthrax, but the duration of antibiotic therapy in naturally occurring CA is controversial. The aim of this study was to compare the clinical outcomes of patients receiving antibiotic treatment for either 3-5 days (group 1) or 7-10 days (group 2) in uncomplicated CA. <i>Methods:</i> A total of 66 patients were enrolled; 29 (44%) in group 1 and 37 (56%) in group 2. Infections were classified as mild (n = 22, 33%) or severe (n = 44, 67%) CA. <i>Results:</i> There were no significant differences between the groups in symptom resolution time, fever clearance time, healing of lesions, development and healing of eschars, requirement for surgical intervention or the development of complications. Both edema resolution time and duration of hospital stay were longer in group 2. There were no therapeutic failures, relapses or deaths in either group. Steroid therapy was used in 32% of patients with severe CA, but a beneficial effect on resolution of edema was not demonstrated. <i>Conclusions:</i> These results suggest that short-course antibiotic therapy is as effective as standard-duration therapy in uncomplicated CA and that steroid therapy may not be effective.

An analysis of children with brucellosis associated with pancytopenia

Brucellosis produces a variety of nonspecific hematologic abnormalities. Hematologic complications of mild anemia and leukopenia have been frequently associated with acute brucellosis, but pancytopenia is less frequently seen. In this study, records of children with brucellosis aged under or equal to 16 years, admitted to Yuzuncu Yil University Hospital between 2004 and 2010, were analyzed retrospectively. Over this time period, 187 patients with brucellosis were diagnosed. Twenty-five (13.3%) of 187 patients had pancytopenia during admission to hospital. The diagnosis of brucellosis was confirmed by standard tube agglutination test in all patients; titers were 1:320 in 1 patient and 1:1280 in 24 patients. Blood culture was positive for Brucella melitensis in 3 patients (12%). Fever was the most common manifestation, followed by malaise, anorexia, sweating, and weight loss. Fever and splenomegaly were the common signs in most patients. In addition, arthritis was observed in 5 patients, and epistaxis, headache, and abdominal pain were observed in 3 patients. The common bone marrow aspiration findings consisted of increased megakaryocytes and hyperplasia of erythroid series, with a shift to the left of the granulocytic series. Histiocytic hyperplasia was observed in the bone marrow smear of 2 patients. Mild hemophagocytosis was observed in the bone marrow of 3 patients. All patients recovered completely, and their peripheral blood counts returned to normal by 2 to 6 weeks after antibiotic treatment of brucellosis. In conclusion, the authors would like to emphasize that brucellosis should be considered in the differential diagnosis of children with pancytopenia.

Antimicrobial susceptibilities of Brucella isolates from various clinical specimens

PURPOSE

Brucellosis is a worldwide zoonotic disease and still constitutes a major public health problem. In the study we claimed to identify Brucella species from clinical samples of patients with active brucellosis from Van region of Eastern Anatolia and to determine in vitro antimicrobial susceptibilities of these strains to commonly used anti-Brucella agents and a possible new alternative tigecycline.

MATERIALS AND METHODS

A total of 56 Brucella isolates were enrolled the study and the identification of the isolates were based on conventional methods. In vitro activities of antimicrobials were evaluated by the E test method.

RESULTS

All isolates were identified as B. melitensis. MIC(90) values of doxycycline, streptomycin, rifampin, trimethoprim-sulfamethoxazole and tigecycline were 0.064 mg/L, 1 mg/L, 2 mg/L, 0.125 mg/L and 0.094 mg/L, respectively. Tigecycline had low MIC(50) and MIC(90) values against all B. melitensis strains; the highest MIC observed was 0.25 μg/mL.

CONCLUSION

Our data suggest that tigecycline can be a therapeutic alternative option for the treatment of brucellosis.

An analysis of children with brucellosis associated with isolated thrombocytopenia

Hematologic abnormalities of mild anemia and leucopenia have been frequently associated with acute brucellosis, but thrombocytopenia are less frequently seen. In the present study, we documented 5 (2.6%) isolated thrombocytopenic patients with the manifestations of brucellosis observed during the course of active infection. Five (2.6%) patients, 4 boys and 1 girl, with ages ranging from 2 to 14 years, had isolated thrombocytopenic at diagnosis. In 5 (2.6%) patients, platelet counts ranged from 39,000 to 120,000/mm(3). Tube agglutination tests for brucellosis were positive for all patients (1/160-1/1280). All patients recovered completely, and their thrombocytopenia returned to normal by 2 to 4 weeks after antibiotic treatment of brucellosis. In our study, we present 5 patients with Brucella-induced thrombocytopenia mimicking idiopathic thrombocytopenic purpura to emphasize the isolated thrombocytopenia and the resolution of thrombocyte counts following treatment of brucellosis.

Disseminated Intravascular Coagulation in a Case of Brucellosis

Brucellosis is a multisystem disease with a broad spectrum of clinical manifestations; hematological abnormalities ranging from fulminant as of disseminated intravascular coagulation (DIC) to anaemia, leucopoenia, thrombocytopenia, and clotting disorders. In this report, we present DIC in a case of brucellosis because of rare presentation. A 3-year-old boy was admitted with the complaints of continuous fever, vomiting, abdominal pain, and bruise on leg. He looked pale and his physical examination revealed purpuric skin lesions on both legs. A mild hepatosplenomegaly was noted on palpation. Laboratory tests showed hematocrit 21%, hemoglobin 7 g/dL, platelet count 20,000/mm3, prothrombin time 19 seconds, activated partial thromboplastin time 48 seconds, plasma fibrinogen level 20 mg/dL, andd-dimer 8 µg/mL. Serum antibrucella titration agglutination test was found to be 1 of 1280 positive. Blood cultures performed on specimens obtained at the time of admission yielded Brucella melitensis. The clinical and laboratory findings were consistent with DIC.

Proton MR spectroscopy and white matter hyperintensities in idiopathic normal pressure hydrocephalus and other dementias

The differentiation of idiopathic normal-pressure hydrocephalus (INPH) from other types of dementia is a clinical challenge. The aim of this prospective study was to evaluate the role of proton MR spectroscopy (MRS) and white matter hyperintensities (WMH) in the diagnosis of INPH, predicting response to therapy and differentiating INPH from other dementias. The study included 18 patients with INPH (Group 1), 11 patients with other types of dementia (Group 2) and 20 control patients (Group 3). The value of WMH scores and MRS findings in diagnosis, evaluation of response to therapy and in the differentiation of INPH from other dementias was statistically evaluated. The level of statistical significance was set at p<0.05 (Kruskal-Wallis and Mann-Whitney U-test). In both Groups 1 and 2, N-acetylaspartate (NAA)/choline-NAA/creatine ratios were significantly less than in the control group (p<0.05). The WMH and MRS findings of Groups 1 and 2 demonstrated no statistically significant correlation (p>0.05). No correlation was found between the outcome of shunt operations and WMH and MRS findings (p>0.05). In conclusion, neither WMH nor MRS were useful in differentiating INPH from other types of dementia. WMH and MRS showed no additional benefit in identifying INPH patients who will better respond to shunt therapy.