ISOLATION OF Cryptococcus neoformans FROM ENVIRONMENTAL SAMPLES COLLECTED IN SOUTHEASTERN NIGERIA

SUMMARY Cryptococcosis caused by Cryptococcus neoformans is the second most common fungal opportunistic pathogen and a lifethreatening infection with serious clinical manifestations especially in HIV/AIDS and other immunocompromised patients. In Nigeria, HIV/AIDS infection has reached an alarming level. Despite this, information on the presence of this fungus in clinical and environmental samples is very scanty in Nigeria and many other parts of Africa. We set out to evaluate the presence of Cryptococcus neoformans or C. gattii in pigeon droppings obtained from Southeastern Nigeria. One hundred and seventy-seven samples of pigeon droppings from six sample types were collected. The area covered comprised of ten cities and other locations spanning across five States in Nigeria. Using established techniques, Cryptococcus neoformans was isolated from 39 of the 177 (22.0%) samples overall. No C. gattiiwas isolated. Most of the isolates (32.4%) were recovered from dovecotes (11 of 34) followed closely by samples taken from markets (31.8%; seven of 22) and least from the church (4.0%; one of 25). The highest isolation rate (38.9%) was found in samples from Enugu-Ezike(seven of 23) while the least came from Afikpoand the other locations each with 9.1% isolation rate. This is the first large-scale screening of Cryptococcus neoformans from pigeon droppings in Nigeria. The ecological and epidemiological significance of these findings are discussed.

On the track of β-lactam resistance: Studies on the regulation of methicillinresistance in Staphylococcus aureus

Dissertação para obtenção do Grau de Doutor em Biologia

A NEW POSSIBILITY FOR SURVEILLANCE: DO WE IDENTIFY ALL CASES OF LEPTOSPIROSIS?

SUMMARY Leptospirosis is a febrile disease with a typically underestimated global incidence, especially in regions where dengue is endemic. Therefore, it is difficult to accurately determine the number of leptospirosis cases in these areas, which contributes to significant under-reporting this disease. In this study, we estimated the number of possible leptospirosis cases among dengue-like cases that were reported during 2008, 2010, and 2012 in the city of Fortaleza, northeast Brazil. Patients were evaluated for dengue and leptospirosis using immunoenzymatic tests for IgM antibodies that were specific to each pathogen. Among the suspected cases of dengue that resulted as negative in laboratory tests, 10.8% (2008), 19.2% (2010), and 30.8% (2012) were confirmed to be leptospirosis. Considering the cases reported by the surveillance authority as dengue that were subsequently discarded based on the laboratory test results, we estimate that the number of actual leptospirosis cases may be 26 to 49 times higher than those diagnosed and reported by the Health Services. Furthermore, we believe that approximately 20% of dengue-like cases may be leptospirosis cases in areas where the two diseases are endemic.

Insights into cell wall synthesis and cell division in Staphylococcus aureus

Dissertation presented to obtain the Ph.D degree in Biology

ANTIBIOTIC RESISTANCE PATTERNS OF URINARY TRACT INFECTIONS IN A NORTHEASTERN BRAZILIAN CAPITAL

Urinary tract infection is a common problem worldwide. Its clinical characteristics and susceptibility rates of bacteria are important in determining the treatment of choice and its duration. This study assessed the frequency and susceptibility to antimicrobials of uropathogens isolated from community-acquired urinary tract infections in the city of Natal, Rio Grande do Norte State capital, northeastern Brazil, from 2007 to 2010. A total of 1,082 positive samples were evaluated; E. coli was the most prevalent pathogen (60.4%). With respect to the uropathogens susceptibility rates, the resistance of enterobacteria to ciprofloxacin and sulfamethoxazole-trimethoprim was 24.4% and 50.6%, respectively. Susceptibility was over 90% for nitrofurantoin, aminoglycosides and third-generation cephalosporins. High resistance rates of uropathogens to quinolones and sulfamethoxazole-trimethoprim draws attention to the choice of these drugs on empirical treatments, especially in patients with pyelonephritis. Given the increased resistance of community bacteria to antimicrobials, local knowledge of susceptibility rates of uropathogens is essential for therapeutic decision making regarding patients with urinary tract infections.

Candida albicans PROTEIN PROFILE CHANGES IN RESPONSE TO THE BUTANOLIC EXTRACT OF Sapindus saponariaL.

Candida albicans is an opportunistic human pathogen that is capable of causing superficial and systemic infections in immunocompromised patients. Extracts of Sapindus saponaria have been used as antimicrobial agents against various organisms. In the present study, we used a combination of two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) and matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) to identify the changes in protein abundance of C. albicans after exposure to the minimal inhibitory concentration (MIC) and sub-minimal inhibitory concentration (sub-MIC) of the butanolic extract (BUTE) of S. saponaria and also to fluconazole. A total of six different proteins with greater than 1.5 fold induction or repression relative to the untreated control cells were identified among the three treatments. In general, proteins/enzymes involved with the glycolysis (GPM1, ENO1, FBA1), amino acid metabolism (ILV5, PDC11) and protein synthesis (ASC1) pathways were detected. In conclusion, our findings reveal antifungal-induced changes in protein abundance of C. albicans. By using the previously identified components of the BUTE of S. saponaria(e.g., saponins and sesquiterpene oligoglycosides), it will be possible to compare the behavior of compounds with unknown mechanisms of action, and this knowledge will help to focus the subsequent biochemical work aimed at defining the effects of these compounds.

INFECTION BY Rickettsia felis IN OPOSSUMS (Didelphis sp.) FROM YUCATAN, MEXICO

Rickettsia felis is an emergent pathogen and the causative agent of a typhus-like rickettsiosis in the Americas. Its transmission cycle involves fleas as biological vectors (mainly Ctenocephalides felis) and multiple domestic and synanthropic mammal hosts. Nonetheless, the role of mammals in the cycle of R. felis is not well understood and many efforts are ongoing in different countries of America to clarify it. The present study describes for the first time in Mexico the infection of two species of opossum (Didelphis virginiana and D. marsupialis) by R. felis. A diagnosis was carried out from blood samples by molecular methods through the gltAand 17 kDa genes and sequence determination. Eighty-seven opossum samples were analyzed and 28 were found to be infected (32.1%) from five out of the six studied localities of Yucatan. These findings enable recognition of the potential epidemiological implications for public health of the presence of infected synanthropic Didelphis in households.

BIOFILM FORMATION OF Vibrio cholerae ON STAINLESS STEEL USED IN FOOD PROCESSING

Vibrio cholerae represents a significant threat to human health in developing countries. This pathogen forms biofilms which favors its attachment to surfaces and its survival and transmission by water or food. This work evaluated the in vitro biofilm formation of V. cholerae isolated from clinical and environmental sources on stainless steel of the type used in food processing by using the environmental scanning electron microscopy (ESEM). Results showed no cell adhesion at 4 h and scarce surface colonization at 24 h. Biofilms from the environmental strain were observed at 48 h with high cellular aggregations embedded in Vibrio exopolysaccharide (VPS), while less confluence and VPS production with microcolonies of elongated cells were observed in biofilms produced by the clinical strain. At 96 h the biofilms of the environmental strain were released from the surface leaving coccoid cells and residual structures, whereas biofilms of the clinical strain formed highly organized structures such as channels, mushroom-like and pillars. This is the first study that has shown the in vitro ability of V. cholerae to colonize and form biofilms on stainless steel used in food processing.

Insights into Campylobacter jejuni Desulforubrerythrin catalytic mechanism

Dissertation presented to obtain the Master Degree in Molecular Genetics and Biomedicine

Role of biotic interactions in generating and maintaining biodiversity

Dissertation presented to obtain the Ph.D degree in Biology.

Enterococcus faecalis V583 prophages: Dynamic interactions and contribution to bacterial pathogenic traits

Dissertation presented to obtain the Ph.D degree in Biology.

Evaluation of pathogenic potential of Aeromonas spp. strains using in vitro methodologies

Dissertation to obtain a Master Degree in Molecular Genetics and Biomedicine

Education in primary school as a strategy to control dengue

The proliferation of Aedes aegypti, a species of mosquito that is the vector of the dengue pathogen, is being augmented by the population's lack of care in allowing the formation of larval habitats. One form of controlling dengue is the distribution of information on the mosquito to improve awareness and to provide the means necessary for the elimination of its reproductive habitats. To evaluate a teaching method concerning the vector and dengue, students from the 5th and 6th years of primary education were compared before and after didactic intervention with a group of control students. The students who received intervention were more successful in identifying the stages of the cycle, biological and morphological characteristics of the adult insect and the importance of the mosquito in health issues. The didactic intervention was successful in developing knowledge leading to increased awareness of the importance of preventative measures that should be taken against the vector and the disease.

Viral etiology of acute respiratory infections among children in Porto Alegre, RS, Brazil

Although acute respiratory infections (ARIs) are a major cause of child morbidity and mortality in Southern Brazil, little information is available on their seasonality and viral etiology. This study was conducted on children under 5 years of age with ARI to assess viral etiology in the State of Rio Grande do Sul, from 1990 to 1992. A total of 862 nasopharyngeal secretion (NPS) samples were tested using indirect immunofluorescence. The results showed that 316 (36.6%) NPS samples were positive: 26.2% for RSV, 6% for adenovirus, 1.7% for influenzaviruses, 1.5% for parainfluenzaviruses, and 1.2% for mixed infection. The mean viral prevalence rates in out-patient services, emergency wards, and in-patient hospital wards were 26.7%, 53% and 42.3%, respectively. Respiratory syncytial virus (RSV) and adenovirus accounted for 91.4 % of the viral diagnoses. RSV was more frequent in children under one year of age at the three levels of health care and was prevalent in infants under six months. Adenovirus was the most prevalent pathogen in hospitalized children, in 1992. Influenza A virus showed an increased prevalence with age among out-patient children. This study shows the annual occurence of viral respiratory infections in the coldest months, with a significant annual variation in the frequency of RSV infection.

Mycetoma fungal infection: multiple organisms as colonizers or pathogens?

We describe a patient with mycetoma or Madura foot, in which histopathological stains of the bone and surface cultures suggested three different organisms including Nocardia species as the cause. Criteria for the diagnosis of the organisms, differentiation between colonizer and pathogen, and significance of mixed infections are discussed.