Invasive behaviour and depolarization effect of Pseudomonas fluorescens on rat cerebellar granule neurons

S Mezghani-Abdelmoula, A Khemiri, O Lesouhaitier, S Chevalier, L Cazin



Previous studies have shown that Pseudomonas fluorescens exerts cytotoxic effects on neurons and glial cells. In the present work, we investigated the time course effect of Pseudomonas fluorescens MF37 and of its lipopolysaccharide (LPS) on cultured rat cerebellar granule neurons. The kinetics of binding of P. fluorescens to cerebellar granule neurons is identical to that of cortical neurons but the binding index is lower, suggesting the presence of a reduced number of binding sites. As demonstrated by measurement of the concentration of nitrites in the culture medium, P. fluorescens induces a rapid stimulation (3 h) of the nitric oxide synthase (NOS) activity of the cells. In contrast, LPS extracted from P. fluorescens requires a long lag phase (24 h) before observation of an activation of NOS. Measurement of the resting membrane potential of granule neurons showed that within 3 h of incubation, there was no difference of effect between the action of P. fluorescens and that of its LPS endotoxin. Two complementary approaches allowed us to demonstrate that P. fluorescens MF37 presents a rapid invasive behaviour, suggesting a mobilisation of calcium in its early steps of action. The present study reveals that P. fluorescens induces the sequential activation of a constitutive calcium dependent NOS and that of an inducible NOS activated by LPS. Ours results also suggest that P. fluorescens cytotoxicity and invasion are not mutually exclusive events.

Key Words: Cytotoxicity, Lipopolysaccharide, Patch-clamp, Invasion, Pseudomonas fluorescens

Afr. J. Clin. Exper. Microbiol. Vol.6(1) 2005: 1-13

Quinolones resistance and R-plasmids of some gram negative enteric bacilli

OA Daini, OD Ogbolu, A Ogunledun



Out of the two hundred and sixty bacteria isolates from clinical specimens obtained from different body sites at the University College Hospital Ibadan, 166 belonged to the family of Enterobacteriaceae and Pseudomonaceae. The isolated gram-negative enteric bacilli consist of Escherichia coli (22), Klebsiella species (65), Proteus species (20), Salmonella typhi (2), Pseudomonas aeruginosa (39) and Pseudomonas species (18). Among the antimicrobial agents tested, high resistance was found with ofloxacin 44.0%, followed by pefloxacin 30.1% and ciprofloxacin 21.7%. Ciprofloxacin has the lowest MIC of 2 – 32 μg/ml while ofloxacin has the highest 64 μg/ml. Of the 166 strains, 44 were resistant to most of the antimicrobial agents tested. All the strains that were resistant to any antimicrobial agents were also resistant to ofloxacin. A total of 27 plasmids ranging in molecular sizes from 6.6.kb to 17.4kb were extracted from the resistant strains and grouped into 5 plasmid profiles. Transformation experiment revealed that 59.2% of the resistant strains carried a common R-plasmid of size 10.7kb. Plasmid-mediated resistance to ciprofloxacin and pefloxacin was found. Klebsiella species harboured the highest number of R-plasmids with 8, followed by Pseudomonas aeruginosa with 4.

Afr. J. Clin. Exper. Microbiol. Vol.6(1) 2005: 14-20

Pattern of resistance to vancomycin and other antimicrobial agents in staphylococcal isolates in a university teaching hospital

BO Olayinka, AT Olayinka, JA Onaolapo, PF Olurinola



Multidrug resistance has been reported in clinical isolates of both coagulase-negative staphylococci (CoNS) and Staphylococcus aureus that are most often resistant to oxacillin/methicillin. Vancomycin, a glycopeptide is the drug of choice for infections caused by such multidrug resistant strains. This study determined the pattern of resistance to vancomycin and other antimicrobial agents in staphylococcal isolates from a University Teaching Hospital. Staphylococcal isolates from clinical specimens submitted to the diagnostic medical microbiology laboratory of the Ahmadu Bello University Teaching Hospital, Zaria (over a three-month period) were characterized using standard microbiological procedures and their susceptibility to vancomycin and other commonly used antimicrobial agents determined by Kirby-Bauer-NCCLS modified disc diffusion technique. A total of 56 of the 97 (57.7%) staphylococcal isolates characterized were resistant to vancomycin 30μg, showing a zone of inhibition less than 15mm. Most of these isolates were from urine (27.3%), wound (21.8%) and pleural aspirate (12.8%). The 56 staphylococcal isolates were made up of 75% (41/56) Staphylococcus aureus and 25% (14/56) coagulase-negative staphylococci. Majority of the isolates, 60.7% (34/56) produced β-lactamase enzyme. Resistance pattern to other antimicrobial agents was benzyl penicillin G (92.9%); tetracycline (69.6%); cefuroxime (60%); chloramphenicol (54.5%); oxacillin (49.1%); erythromycin (35.7%); gentamicin (25%) and ciprofloxacin (16.1%). Analysis of the multiple antibiotic resistance index (MARI) showed that majority (91.1%) were resistant to 3 to 7 of the other antimicrobial agents tested. No isolate was resistant to all the tested antimicrobial agents. A very high proportion of the staphylococcal isolates were resistant to vancomycin, a glycopeptide that is not commonly used in this environment. Ciprofloxacin and gentamicin appear to be the only agents that will be effective in treating infections by these isolates. The high proportion of isolates with MARI of 0.3 and above, suggest that the isolates originated from an environment where antibiotics are often used. There is need for constant, on-going antimicrobial resistance surveillance in important and commonly isolated clinically significant pathogens to form the basis for developing and implementing measures that will reduce the burden of antimicrobial resistance.

Key Words: vancomycin, methicillin resistance, Staphylococcus aureus, coagulase-negative staphylococci, antimicrobial agents

Afr. J. Clin. Exper. Microbiol. Vol.6(1) 2005: 21-27

Observations on the tolerance of young dogs (puppies) to infection with Trypanosoma congolense

JN Abenga, K David, COG Ezebuiro, FAG Lawani



Studies were undertaken to assess the susceptibility of young local dogs to infection with Trypanosoma congolensei. Six puppies (7 weeks old) were used for the study. Although the puppies became parasitaemic 6 to 7 days post infection, they were tolerant to infection as the parasitaemia remained low through out the first seven weeks of the eight week observation period. The packed cell volume (PCV) also only dropped slightly during the last four weeks attaining the value of 25.6 + 3.8 (p>0.05) by the eighth week while the mean body weight continued to increase. Similarly, the mean daily body temperature did not differ significantly from those of un-infected control. The significance of trypanotolerance in Nigerian local dogs is discussed.

Key Words: local puppies, low parasitaemia, packed cell volume, Trypanosoma congolense, trypanotolerance, Nigerian

Afr. J. Clin. Exper. Microbiol. Vol.6(1) 2005: 28-33

nfluence of highly active antiretroviral therapy (HAART) on the survival of HIV-infected patients: part report of the Ilorin Trial Center

AK Salami, PO Olatunji, EA Fawibe, PO Oluboyo



This report is part of the ongoing highly active antiretroviral therapy (HAART) trial, 167 patients were enlisted, but current analysis was restricted to 107 patients that were about a year old on the programme. The baseline weight, CD4+ cell count and serum albumin of 59 males and 48 females age 15-60 years, were compared with values at 12 months of administration of HAART. Patients mean weight, CD4+ count and serum albumin increased significantly (p-value < 0.05) by 9.7kg, 127.4/uL and 9.1g/L over the enrolment values. Side effects of antiretroviral (ARV) drugs were mild and included; rashes 19.6%, jaundice 7.5% and reactive arthritis 3.5%. Fifty-eight patients (59%) were alive by the end of 1 year, 33 (30%) had died and 11 (10.8%) were lost to follow-up. The risk of death increased 3 times when baseline CD4+ count was less than 116.8/uL (RR= 3.36, 95%CI=1.86– 6.06, P-value = 0.000048). TB/HIV co-infection raised the chance of death twice (RR= 2.33, 95%CI=1.31-4.15, P- value=0.005). In conclusion, the use of triple-drug combination of HAART has led to improved CD4+ cell count and resolution of clinical symptoms in HIV/AIDS patients. These resulted in increased survival.

Key Words: HAART, AIDS, CD4+ cells count and survival.

Afr. J. Clin. Exper. Microbiol. Vol.6(1) 2005:34-39

Liver function tests in HIV-1 infected asymptomatic patients and HIV-1 AIDS patients without hepatomegaly in Lagos, Nigeria

PS Ogunro, DP Oparinde, AB Okesina



Hepatic functions were assessed by serum assays of albumin (ALB), total protein (TP), total bilirubin (TB), conjugated bilirubin (CB), serum activities of alanine transaminase (ALT), aspartate transaminase (AST), alkaline phosphatase (ALP) and gamma – glutamyl transferase (GGT) in 51 HIV-1AIDS patients, 38 HIV-1 infected asymptomatic patients and 56 age and sex matched healthy HIV negative controls. The mean ± SEM serum ALB concentration of 23.5 ± 1.2 g/L in AIDS patients was significantly lower (p < 0.001) than those of HIV-1 infected asymptomatic patients and healthy controls; 38.9 ± 3.1g/L and 39.4 ± 2.8g/L respectively. The mean ± SEM TB concentration of 17.8 ± 1.3 μmol/L in AIDS patients was significantly higher (p < 0.01) than 11.7 ± 1.1μmol/L observed in HIV-1 infected asymptomatic patients and 10.8 ± 2.1μmol/L in the controls. Similarly, there was a significant elevation (p < 0.05) in serum CB concentration of 6.5 ± 0.9µmol/L in AIDS patients compared to HIV-I infected patients of 3.8 ± 1.0 μmol/L and controls of 3.1 ± 0.8 μmol/L. The mean ± SEM ALT, AST, ALP and GGT activities (iu/L) of 48.7 ± 3.1, 54.3 ± 3.3, 84.8 ± 4.3 and 47.5 ± 4.1 respectively in AIDS patients were significantly higher (p < 0.001) than 21.3 ± 2.9, 25.6 ± 1.3, 56.4 ± 3.2 and 25.1 ± 1.7 respectively observed for the same enzymes in HIV-1 infected patients and 20.1 ± 3.1, 24.5 ± 2.6, 54.6 ± 4.3 and 24.2 ± 2.1 respectively in the controls. These results provide evidence to suggest that hepatic damage is greater in AIDS patients than in HIV-1 infected asymptomatic patients even in the absence of hepatomegaly. We conclude that this may be due to opportunistic infections that set in at the later part of HIV-1 infection (i.e. at AIDS stage) or increase severity of HIV-1 infection or both.

Key Words: HIV-1 infected asymptomatic patient, AIDS, Hepatic functions

Afr. J. Clin. Exper. Microbiol. Vol.6(1) 2005: 40-45

Health workers’ attitude and perception toward routine pre-marital HIV screening

OI Musa



More than half of all new HIV infections occur among young adults, however, the rate of new infections among women surpasses men’s especially in Sub-Saharan Africa. This rising infection rates, particularly among women, exposes children to increased HIV risk even before they are born. This descriptive cross-sectional study was conducted to determine the attitude and perception of health workers to routine pre-marital HIV screening that is currently practice by some religious institutions as part of initiative directed towards controlling the spread of the infection. Three hundred (300) self-administered questionnaires distributed to the health workers in their respective units were analyzed. Majority of the respondents 270 (90%) agreed that pre-marital HIV screening is necessary and advantageous to couples intending to get married. Although more than half of the respondents (56.7%) believed that the screening exercise is associated with some disadvantages, as many as 205 (68.3%) were in support of its enforcement for all couple. Majority 260 (86.7%) agreed that religious leaders/institutions have important role to play in HIV control and most of them 265 (88.3%) would prefer that Government health facilities be used as screening centres; and medical doctors should be the person to reveal the test results to the couples 275 (91.7%). About two-third of the respondents felt that the couples should initiates request for HIV screening, and on the issue of whether or not the marriage should be contracted following a positive result in one or both partners, 180(60%) respondents felt that the decision should be made by the couple. Counseling of couples before and after HIV screening, adequate training of health workers on HIV counseling skill and making HIV screening free to couple were suggested by the respondents as incentive that would enhance voluntary pre-marital HIV testing.

Afr. J. Clin. Exper. Microbiol. Vol.6(1) 2005: 46-52

Sero-prevalence of hepatitis C virus amoung patients attending STD clinic in Ibadan, Nigeria

AA Oni, GN Odaibo, OD Olaleye, RA Bakare, SO Ola



In the tropics, hepatitis C virus (HCV) seroprevalence ranges from < 0.2% in whole Africa. A strong association between HCV and hepatitis B surface antigen (HBsAg)-negative chronic liver disease and hepatocellular carcinoma has been described. Hepatocellular carcinoma (HCC) is one of the most common cancers among Africans, and in Nigeria by 1970 the estimated rate was 6.6 per 100,000 populations per annum. Sexual transmission was regarded as a minor cause of HCV, the degree of which has not been properly evaluated in most environments. Since it has been established that sexual transmission is an important mode of acquisition of the infection, we therefore set out to find the seroprevalence of HCV among 95 patients attending sexually transmitted diseases (STD) clinic in University College Hospital, Ibadan, Nigeria with a view to recommending preventive and control measures of HCV in our community. The sera collected from these respondents were used for screening for syphilis using the VDRL test, and for HCV antibodies using the MONOLISA anti-HCV (Sanofi, Pasteur France). Mid-stream urine was collected from all participants, and urethral swabs from all male participants while endocervical and high vaginal swabs were collected from female participants. Ulcer swabs were collected from those with genital ulcers. The prevalence of HCV infection was found to be 37.9% in patients presenting with STDs. This comprised 38.9% of males and 61.1% females. This prevalence rate is very high compared with the rate in the general population and other “high-risk” groups in previous studies in the same environment. Factors associated with HCV infection in this environment include high heterosexuality, high level of education, and previous instrumentations such as in scarifications and termination of pregnancy. Prevention and control of STDs will definitely reduce HCV infection and hence the attendant consequences, particularly hepatocellular carcinoma, in our environment.

Afr. J. Clin. Exper. Microbiol. Vol.6(1) 2005: 53-59

Prevalence of measles neutralizing antibody in children under 15 years in Southwestern Nigeria

OO Opaleye, MO Adewumi, E Donbraye, AS Bakarey, GN Odaibo, OD Olaleye



The immune status of children under 15 years in the Southwestern region of Nigeria against measles virus was determined using the neutralization test with a view to assessing the herd immunity to the virus in these communities. A total of 256 serum samples collected from children were tested by the beta method of neutralization. Forty (15.6%) of these samples were found to be positive at a titre of 1:256, 35 (13.7%) at 1:128, 36(14.1%) at 1:64, 37(14.5%) at 1:32, 38 (14.8%) at 1:16, 27 (10.5%) at 1:8 and 16 (6.3%) at 1:4. Twenty-seven (10.5%) of the 256 samples had no detectable antibody to the measles virus. There was no significant relationship between the antibody titre to measles virus and the gender of the children (p > 0.05). Also, there was no significant difference using Chi square analysis between the neutralizing antibody titres and the age of the children (p > 0.05). All the children whose samples were tested were vaccinated against measles as attested to by their parents. However, the vaccination does not seem to protect all the children, for some of them had no detectable neutralizing antibody while some had low neutralizing antibody titre. In Nigeria, where only a single dose of measles vaccine is given at 9 month, measles may remain a serious threat to the children population with its attendant high morbidity and mortality.

Key Words: Prevalence, Neutralizing antibodies, Children < 15years

Afr. J. Clin. Exper. Microbiol. Vol.6(1) 2005: 60-63

Sexually transmitted infections in Obafemi Awolowo University Teaching Hospital, Ile-Ife, Nigeria: A decade of clinic experience

AO Oyelese, AO Onipede, AO Aboderin, AN Adedosu, O Onayemi



Sexually transmitted infections (STIs) remain cosmopolitan in all societies of the world and in some cases assume epidemic proportions. These infections are common infectious diseases nowadays, with an annual incidence of more than 200 million cases a year. Venereal pathogens continue to increase in number and the spectrum of pathogens has limitless elasticity. While genital discharge and ulceration are common presenting symptoms, unusual findings on examination and investigation are not uncommon. We assessed our clinic experiences during the first ten years in an STI clinic. Salient findings are that 85% of all patients seen have an STI. The breakdown of infections revealed that Candida albicans was the most common venereal pathogen accounting for 24% while Neisseria gonorrhoeae accounted for about 18.0%. Sarcoptes scabiei and Phthirus pubis causing scabies and pediculosis accounted for 1.8% and 0.3% respectively. As commonly established, the age bracket 19 to 39 years was clearly the age group in which sexually transmitted infections were mostly diagnosed. In a control programme, this age group should be targeted, while there is the need to continue to stimulate awareness of both the general public and health workers at all levels on the problems of sexually transmitted infections, the scourge of all ages.

Key Words: Sexually transmitted infections, venereal pathogens, clinic experience, control awareness

Afr. J. Clin. Exper. Microbiol. Vol.6(1) 2005: 64-68