Microbiologie médicale et diagnostic

Background: Staphylococcus aureus is one of the most virulent gram positive bacteria. It produces a lot of toxins and enzymes, most of which are virulent factors. Among the enzyme that produces is the catalase which is very useful in differentiating staphylococci from streptococci [1]. Since the catalase is nearly ubiquitous among some of organisms that can grow in the presence of oxygen (air). It promotes the conversion of hydrogen peroxide, a powerful and potentially harmful oxidizing agent, to water and molecular oxygen; so the major function of catalase within cells is to prevent the accumulation of toxic levels of hydrogen peroxide formed as a by-product of metabolic processes - primarily that of the electron transport pathway [2].

Objectives: The main aim of this study is to prove that human WBCs can produce H2O2, this H2O2 when react with catalase producing S. aureus can easily be degraded to H2O + O2.

Methodology: In this study a total of 40 subjects were included. Aliquots of 2.5 ml of venous blood were collected by venous puncture after disinfectant the site of collection with 70% alcohol and the collected blood was drawn into EDITA containers (20 subject) and anticoagulant free containers (other 20 subject), centrifugation for 5 minute at 1500 RPM, then the separated sera and plasma were converted to new sterile eppendrof tubes and freezing until used (before used we will leaves the eppendrof tubes at room temperature for DE freezing). Standard catalase producing S. aureus were used by taking 1 colony from Mac- conkey media by using applicator wooden stick, and inserted in eppendrof tube, then after that waited for the appearance of air bubbles to indicate occurrence of the reactions.

Results: According to this study, it was proved that WBCs in human plasma or serum can produce H2O2, this H2O2 were reacted with colony of S. aureus to produce air bubbles and water when S. aureus producing catalase enzyme and so on there were no differences between using H2O2 or human plasma / serum that contains WBCs to detect and identify of S. aureus by both techniques

Conclusion: Based on the results of this study, we can use WBCs that were found in human plasma or serum to identify catalase producing S. aureus.

Escherichia coli K12 are currently the best-understood organism on Earth; a larger fraction of its genes have been functionally characterized than for any other organisms. However, organisms given this species designation are extremely diverse, genetically and phenotypically. E. coli proves to be a valuable model system for understanding bacterial physiology, metabolism, genetics and pathogenesis. Why has E. coli been so much more extensively studied than any other bacterium on Earth? It all began with the German pediatrician and bacteriologist, Theodor Escherich, who was dismayed to find that so many babies were dying of diarrhea diseases. In fact, we now know that E. coli is one of the top causes of infant mortality, adult diarrhea and urinary tract infections worldwide. It was because of the organism's broad host specificity and ability to cause many different diseases in large numbers of animals, including humans, that it was first selected as an important bacterium for study. More recently, it has been found that certain strains of E. coli are probiotic, having beneficial effects on host animals, counteracting the detrimental consequences of their pathogenic counterparts. Genetic analyses have revealed that the tremendous phenotypic diversity of the hundreds of currently recognized E. coli strains resulted from the frequent occurrence of horizontal gene transfer during the evolutionary divergence of the Escherichia genus. In fact, the pan genome of E. coli far exceeds the core genome, by up to 20-fold or more. Thus E. coli should not be thought of as an entity or species; it represents an entire spectrum of related organisms sharing only the core housekeeping genes.

Minimization or elimination of antibiotic resistance in microbial species is an urgent need of the present times. Antimicrobial photodynamic therapy is a new therapeutic option through which development of resistance in microorganisms can be avoided. Interest in the use of photodynamic therapy to combat microbial infection is not only linked to the fact that this technique prevents antibiotic resistance in microorganisms, but is also due to the broad-spectrum antimicrobial effect, selectivity, with little or no local or systemic side effects, to microorganisms, ease of application of the technique, among other beneficial features. In this review, the major aspects related to the use of antimicrobial photodynamic therapy with respect to the major photosensitizing dyes and light sources used in the therapy have been discussed. In addition, current applications, wherein the use of the technique has yielded successful results, have also been discussed along with the possibility of future applications of this new therapeutic option to combat infections.

The adhesion of bacteria to target tissues is frequently a necessary first step in pathogenesis. Blocking of such adhesion can provide an efficient way of interfering in bacterial infections. A wide spectrum of microbial pathogens bind to cell surface heparan sulfate proteoglycans in order to facilitate adherence, attachment and cellular entry, as well as to evade defense mechanisms. Knowledge of these mechanisms is important for the development of novel antimicrobial agents and new therapies.

Leprosy is chronic granulomatous disease caused by Mycobacterium leprae and associated with the disability, stigma and discrimination to the affected individuals. Though often considered a disease of antiquity, it is found most commonly today in tropical and sub-tropical regions. Global efforts to eradicate leprosy have been largely successful in controlling its spread. Despite these efforts, the disease remains endemic countries emphasizing the need for greater scrutiny of its epidemiology. Strain typing and strain differentiation by Variable Number Tandem repeats (VNTR) could be useful in tracing origins and routes of infection, general leprosy surveillance and prevalence. Strain typing of Mycobacterium leprae by VNTR has been successfully carried out and predominance of leprosy bacilli in different geographical region also done by VNTR. In the present review, we reported global distribution M. leprae by Variable Number tandem repeats in systematic way to easy understanding of leprosy distribution.

Introduction: Of the known mycotoxins, the most important in relation to direct hazard to human health are the aflatoxins.

Aim: to determine the level of exposure of aflatoxin from mother to child and its mode of transfer.

Patients and Method: 570 pregnant women in the labour ward of The Federal Medical Centre Yola were investigated for their aflatoxin content by using the velasco fluorotoxin meter which comprised of 89 samples of amniotic fluid, 213 of serum from maternal blood and 211 serums from neonatal cord blood; 57 of those were controls.

Results: The Aflatoxin values of G1, G2, and M2 above 20 ppb were obtained in 66 samples of the amniotic fluid (74.1%); 133 from venous maternal blood (62.4%) and 142 from neonatal cord blood (67.2%). blood.

Conclusion: This results is suggestive that aflatoxin present in maternal blood crosses the transplacental barrier and accumulates in the foetus which further explains the high concentration of aflatoxin in the amniotic fluid and the in utero exposure to these toxins.

Background: The utility of serum procalcitonin (PCT) for differentiating pulmonary tuberculosis (TB) from bacterial acquired pneumonia (AP) in Benin Metropolis (Nigeria), a country with an intermediate TB burden.

Aim: To determine the bacterial acquired Pnuemonia from Mycobacterium tuberculosis associated pneumonia with the aid of procalcitonin levels

Methods: We conducted a prospective study, enrolling 170 participants with suspected AP in a community-based referral hospital. A clinical assessment was performed before treatment, serum and PCT were measured. The test results were compared to the final diagnoses.

Results: Of the 170 patients, 98 had bacterial acquired pneumonia and 52 had pulmonary TB. The median PCT level was 0.528 ng/mL (range, 0.01 to 27.75) with bacterial acquired pneumonia and 0.042 ng/mL (range, 0.01 to 0.87) with pulmonary TB (p<0.001). No difference was detected in the discriminative values of PCT (p=0.733).

Conclusions: The concentrations of PCT differed significantly in patients with pulmonary TB and bacterial acquired Pneumonia. The high sensitivity and negative predictive value for differentiating pulmonary TB from bacterial acquired pneumonia suggest a supplementary role of PCT in the diagnostic exclusion of pulmonary TB from bacterial AP in areas with an intermediate prevalence of pulmonary TB.

Background: Community-acquired pneumonia (CAP) is associated with high mortality. Drug resistance is common in countries where the alternative treatments are limited and available drugs are misused. In resource limited countries like Ethiopia; it is wise to determine antimicrobial susceptibility pattern of common bacterial pathogens of CAP. The objective of our study was to determine antimicrobial susceptibility pattern of common bacterial pathogens of CAP among adult patients visiting Arba Minch Hospital.

Methods: A cross sectional study conducted at Arba Minch Hospital, Southern Ethiopia from February to May 2013. Sputum specimens were collected; microbiological investigations and antimicrobial susceptibility testing were performed using standard procedures. Data was processed and analyzed with SPSS version16.0. Results: Out of 170 cases, only 73 (42.9%) were culture positive. Majority of tested bacterial isolates (>86%) were sensitive to Ceftriaxone and Ciprofloxacin. Most S. pneumoniae isolates (60%) were resistant to Oxacillin. Most of S. aureus and gram negative bacterial isolates were resistance to Tetracycline (100%), Penicillin (83.3%), Ampicillin (50-100%), Doxycycline (50-100%), and Trimethoprim-sulfamethoxazole (83.3-100%). Multidrug resistance (MDR) was observed to most (60.3%) bacterial isolates.

Conclusion: Antimicrobial resistance including MDR was observed to a number of commonly used antibiotics, such as trimethoprim- sulfamethoxazole, penicillin groups and doxycycline. Hence, periodic monitoring of drug resistant pattern is essential for better management of CAP.

Skin conditions affecting the Nigeria populace are mostly infective skin diseases. Various studies across the population done in schools, community or as hospital-based prevalent studies showed that superficial fungi infections made up majority of these infections. These infections constitute the highest number of dermatoses or skin infections treated by dermatologists all over the country. The prevalence of superficial fungi infections has also been observed to remain the same, and in some places, it has increased over decades. Superficial fungi infections still need to be addressed as a public health problem among the growing populace of Nigeria. The favorable environment of hot and humid climate, poverty, poor sanitary conditions and overcrowding are well known factors that favor these fungi growth. These conditions well abound in Nigeria.

Background: Community-acquired pneumonia (CAP) is associated with high mortality. Drug resistance is common in countries where the alternative treatments are limited and available drugs are misused. In resource limited countries like Ethiopia; it is wise to determine antimicrobial susceptibility pattern of common bacterial pathogens of CAP. The objective of our study was to determine antimicrobial susceptibility pattern of common bacterial pathogens of CAP among adult patients visiting Arba Minch Hospital.

Methods: A cross sectional study conducted at Arba Minch Hospital, Southern Ethiopia from February to May 2013. Sputum specimens were collected; microbiological investigations and antimicrobial susceptibility testing were performed using standard procedures. Data was processed and analyzed with SPSS version16.0.

Results: Out of 170 cases, only 73 (42.9%) were culture positive. Majority of tested bacterial isolates (>86%) were sensitive to Ceftriaxone and Ciprofloxacin. Most S. pneumoniae isolates (60%) were resistant to Oxacillin. Most of S. aureus and gram negative bacterial isolates were resistance to Tetracycline (100%), Penicillin (83.3%), Ampicillin (50-100%), Doxycycline (50-100%), and Trimethoprim-sulfamethoxazole (83.3-100%). Multidrug resistance (MDR) was observed to most (60.3%) bacterial isolates.

Conclusion: Antimicrobial resistance including MDR was observed to a number of commonly used antibiotics, such as trimethoprim- sulfamethoxazole, penicillin groups and doxycycline. Hence, periodic monitoring of drug resistant pattern is essential for better management of CAP.