Network of Recurrent events - A case study of Japan

A recently proposed method of constructing seismic networks from 'record breaking events' from the earthquake catalog of California (Phy. Rev. E, 77 6,066104, 2008) was successfull in establishing causal features to seismicity and arrive at estimates for rupture length and its scaling with magnitude. The results of our implementation of this procedure on the earthquake catalog of Japan establishes the robustness of the procedure. Additionally, we find that the temporal distributions are able to detect heterogeneties in the seismicity of the region.Comment: 13 pages, 6 figures, 1 tabl

Interplanetary Consequences of a Large CME

We analyze a coronal mass ejection (CME) which resulted from an intense flare in active region AR486 on November 4, 2003. The CME propagation and speed are studied with interplanetary scintillation images, near-Earth space mission data, and Ulysses measurements. Together, these diverse diagnostics suggest that the internal magnetic energy of the CME determines its interplanetary consequences.Comment: 5 pages, 9 figures, To appear in "Magnetic Coupling between the Interior and the Atmosphere of the Sun", eds. S.S. Hasan and R.J. Rutten, Astrophysics and Space Science Proceedings, Springer-Verlag, Heidelberg, Berlin, 200

Urinary tract infections at Aga Khan University hospital Nairobi - A one year experience

Background: In developing countries, most of these patients with urinary tract infections (UTI) are normally treated empirically and urine culture is usual ordered for as a last resort in patients refractory to antibiotic treatment.Objective: To explore the possibility of designing empiric antibiotic therapy for symptomatic UTI in patients at Aga Khan University Hospital by looking at the trends of UTI, common pathogens isolated and their antibiotic susceptibility pattern.Design: A retrospective clinical-laboratory study.Setting: Aga Kahn University Hospital- Nairobi.Subjects: All positive urine cultures between January and December 2008 were included in the study.Results: A total of 409 urine specimens were retrieved and analysed and 100 cases had negative cultures. Three hundred and nine cases had positive cultures. Sixty eight point seven percent were females while 31.3% were males with a mean age of 31 years. One hundred and thirty five out of 409 patients (33%) had classical signs and symptoms. In 143 (35%) cases E. coli was isolated. The other cultures were organisms other than E.coli. There was a higher resistance to clotrimazole in E. coli (71%) as compared to non- E. coli organisms (23%). There was a higher resistance rate to Nalidixic acid in non-E. Coli organisms (35%) and higher resistance rate to Augmentin in E. Coli 43 versus 18% (c/f non-E.Coli). Forty patients in the study had predisposing factors for UTI.Conclusions: It is sometimes warranted to start the patient on empiric antibiotic treatment before culture results are available. Nitrofurantoin, Cefuroxime, Ciprofloxacin have good sensitively rates and are therefore drugs of first choice for the treatment of uncomplicated urinary tract infection provided that the contraindications and specific precautions are noted

Antibacterial susceptibility patterns of blood stream isolates in patients investigated at the Aga Khan University Hospital, Nairobi

Background: Microbial invasion of the blood stream can have serious immediate consequences and are a threat to every organ in the body. Timely detection and treatment is vital and necessitates hospital admission and immediate intervention.Objectives: To investigate aetiology and anti-microbial resistance patterns of bacterial isolates in blood stream infections.Design: A retrospective clinical-laboratory study carried over a five year period January 2003 to April 2008.Setting: The Aga Khan University Hospital, Nairobi, Department of Pathology, Division of Microbiology.Subjects: All blood culture specimens received from both in and out-patients’ at the Aga Khan University Hospital’s laboratory.Results: Rates of oxacillin resistance for Staphylococcus aureus were 21%. Streptococci were generally susceptible to beta-lactams. High-level gentamicin resistance was seen in 12% of Enterococci. Vancomycin resistance was conspicuously absent. Resistance rates of Pseudomonas aeruginosa to ciprofloxacin, gentamicin, amikacin, imipenem were between 11% and 23%. Salmonella spp. showed multiple resistant patterns toco-trimoxazole, chloramphenicol and ampicillin with resistance rates of greater than 35%. One hundred and twenty three patients (11%) tested positive for HlV. Unlike in HlV negative individuals, Cryptococcus neoformans was an important isolate, positive in 5%. A number of HlV positive patients had Staphylococcus aureus and coagulase negative staphylococcus isolates in their blood cultures. In such clinical circumstances it is difficult to determine the clinical significance of these isolates. Conclusion: Antimicrobial susceptibility patterns revealed high level resistance among the gram positive organisms and also amongst extended spectrum beta lactamase (ESBL) producing E.coli and Klebsiella spp. This study highlights the challenges of deriving empiric drug regimens in the current clinical scenario. However, we do know it is important to cover adequately for gram positive organisms

Species distribution and antifungal sensitivity patterns of vaginal yeasts

Objectives: To identify yeast isolates in vaginal specimens to species level and determine their antifungal susceptibility patterns.Design: Cross-sectional laboratory-based study.Setting: The Aga Khan University Hospital (AKUH), Nairobi.Subjects: Yeast isolates from high vaginal swabs presented to the laboratory for culture and sensitivity were identified to species level using the API Candida system and subjected to broth microdilution susceptibility testing.Main outcome measures: Frequency tables and graphs were used to summarise the data. Susceptibility data was analysed by the non-parametric Fisher’s exact test. P0.05) between the susceptibility of C.albicans and non-albicans isolates to flucytosine and amphotericin B, however there was a significant difference (

Network of Earthquakes and Recurrences Therein

We quantify the correlation between earthquakes and use the same to distinguish between relevant causally connected earthquakes. Our correlation metric is a variation on the one introduced by Baiesi and Paczuski (2004). A network of earthquakes is constructed, which is time ordered and with links between the more correlated ones. Data pertaining to the California region has been used in the study. Recurrences to earthquakes are identified employing correlation thresholds to demarcate the most meaningful ones in each cluster. The distribution of recurrence lengths and recurrence times are analyzed subsequently to extract information about the complex dynamics. We find that the unimodal feature of recurrence lengths helps to associate typical rupture lengths with different magnitude earthquakes. The out-degree of the network shows a hub structure rooted on the large magnitude earthquakes. In-degree distribution is seen to be dependent on the density of events in the neighborhood. Power laws are also obtained with recurrence time distribution agreeing with the Omori law.Comment: 17 pages, 5 figure

Phenotypic characterization of Candida Albicans from clinical sources in Nairobi, Kenya

Objective: To isolate and carry out phenotypic characterization Candida species from clinical sources in Nairobi Kenya. Study design/setting: Laboratory Based Experiment at Mycology Laboratory, Kenya Medical Research Institute, Nairobi, Kenya. We studied 130 Candida s species isolated between 2000 - 2005. The isolates were from blood, stool, urine, CSF and swabs of patients from different health Institutions in Nairobi. Methods: Preliminary identification was done using morphological features and CHROMagar and confirmed using Analytical profile index (API 20 C aux). Results: Candida albicans were 130/150 (86.7%) whereas 13.3% were non albicans Candida and included; C. parapsilosis 4%, C. tropicalis 2.7%, C. krusei 2.7%, C. guilliemondii 1.3% and C. famata, 1.3%. Germ tube positive C. albicans were 96.1% while only 3.8% were germ tube negative. All the 130 isolates identified as C. albicans formed chlamydospores on Corn meal agar and all grew at both 370C and 45 °C ruling out the possibility of Candida dubliniensis. Conclusion: Non albicans candida are of clinical significance and may warrant the need speciate Candida species from clinical setting and constantly monitor for fungal resistance as some Candida species are intrinsically resistant to certain antifungal drugs especially in the context of opportunistic infections in HIV/AIDS

A Five Year Review OF API20E Bacteria Identification System’s Performance at a Teaching Hospital

Objectives: To assess the performance of the API20E bacteria  identification system at a teaching hospital in Kenya.Design: Retrospective study.Setting: The microbiology laboratoryoratory of the Aga Khan University teaching Hospital.Subjects: One thousand six hundred and fifty eight API20E records.Main outcome measures: The accuracy in identifying the bacteria species.Results: One thousand four hundred and forty two (87.6%) isolates had the exact identity, 199 (12%) nearest identity, and seven (0.4%) no identity. The performance varied among the species; Acinetobacter baumanii had 140 (99.3%) isolates with the exact identity and only one (0.7%) with the nearest identity compared with Aeromonas hydrophila which had five (17.2%) with exact and 24 (82.8%) with nearest.Conclusions: The API20E system is a robust bacteria identification method which can serve small and medium clinical microbiology laboratoryoratories that may not afford automated systems. Adhering to the manufacturer’s instructions and good laboratoryoratory practice can improve the  performance of this method