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Review Article: Prospect and Progress of Malaria Vaccine Development

OA Adeyeba, AF Fagbenro-Beyioku, O Ojurongbe

 

Abstract

Malaria kills one child every 30 seconds in Africa. The development of a safe vaccine remains an urgent unmet need which could greatly control and even lead to the eradication of the disease. The success recorded in the recent vaccine trials have given some ray of hope that a safe and effective vaccine against malaria will soon be produced. In this article, we bring together important published information on the status of malaria vaccine development and reviewed some field trials and the obstacles as well as prospect for effective malaria vaccination.
Key words: Malaria vaccine, prospect, review

Afr. J. Clin. Exper. Microbiol. 2005; 6(2): 145-152

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Review Article: ‘Miasma’ Theory and the Possibility of Malaria Eradication

Ademola O Awoyemi

 

Abstract

Malaria as a disease entity caused by plasmodium species only became recognized towards the end of the 19th Century. Prior to that time, Mal’aria or ‘bad air’ was believed to be the cause of fevers or paludal. This article traces the history of ‘Miasma’ theory which had been accepted for Centuries before the ‘Germ’ theory became established. Comparing the ‘Miasma’ theory with current understanding of Africans about disease causation, it was concluded that there are great similarities. It is therefore recommended that concurrent application of both the ‘Germ’ theory and the ‘Miasma’ theory could lead to a more effective control or even global eradication of malaria.
Key words: Miamsa, malaria, eradication

Afr. J. Clin. Exper. Microbiol. 2005; 6(2): 153-158

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Epidemiological Study Of Asymptomatic Bacteriuria Among Nursery School Children In Ahvaz, Iran

M Jalali, T Asteraki, E Emami-Moghadam, E Kalantar

 

Abstract

This study was undertaken to determine the prevalence of asymptomatic bateriuria in preschool children of different age and sex groups and to isolate the organisms responsible for asymptomatic bacteriuria and determine their antimicrobial susceptibility pattern. A total of 475 children from 17 nurseries in Ahvaz city, Iran were screened by collecting mid-stream urine samples for the presence of causative organisms. Asymptomatic bacteriuria was observed in 16 cases (3.36%). The isolated pathogens included Escherichia coli (50 %), Proteus mirabilis (25 %) and coagulase negative staphylococcus (25 %). The antibiograms indicated that Gentamicin (100 %), Nalidixic acid (100 %), Amikacin (75%), Kanamycin (75 %), Nitrofurantoin ( 62.5 %), Tobramycin ( 62.5 %), Tetracycline ( 50 %) and Chloramphenicol (37.5%), were in that order the most effective of the antibiotics tested against E. coli isolates. Proteus mirabilis showed 100% sensitivity to Amikacin, Gentamicin, Kanamycin, Nalidixic acid and Tobramycin followed by Nitrofurantoin (75%), Cephalotin (50%) and Chloramphenicol (50%). Similarly, antibiogram of coagulase negative staphylococcus showed 75% sensitivity to both Nalidixic acid and Kanamycin. This result indicated a significant rise in the frequency of Escherichia coli in asymptomatic bacteriuria.
Key words: Asymptomatic bacteriuria, children, urinary tract infections

Afr. J. Clin. Exper. Microbiol. 2005; 6(2): 159-161

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Characteristics of Nosocomial MRSA in Assir Central Hospital, Abha, Kingdom of Saudi Arabia

T Al-Azraqi, CSS Bello

 

Abstract

The objective of this study is to determine the characteristics of nosocomial methicillin-resistant and sensitive Staphylococcus aureus (MRSA & MSSA) and their minimum inhibitory concentration (MIC) to vancomycin and oxacillin. Over a six-month period a study of Staphylococcus aureusisolates from clinical specimens of patients with nosocomial infections in Assir Central Hospital (ACH), Abha, Saudi Arabia, between September 2003 and February 2004, was carried out. Isolation and identification of Staphylococcus aureus was performed using standard microbiological methods. MIC to vancomycin and oxacillin was carried out using the E-test strips. Eighty-five Staphylococcus aureus isolates were identified. These were made up of 39 (45.9%) MRSA and 46 (54.1%) MSSA. The MIC to oxacillin showed that 37/39 (94.9%) MRSA had MIC >256 µg/ml and only 2/39 (5.1%) had MIC of 4 and 32 µg/ml. Thirty of forty six (65.2%) of the MSSA had MIC < 0.50 µg/ml and 16/46 (34.8%) had MIC of between 0.50 -2 µg/ml. All the 85 isolates were fully sensitive to vancomycin (MIC breakpoint < 4 µg/ml). There is even distribution of sensitivity pattern to vancomycin among MRSA and MSSA isolates. 31/39 (79.5%) of MRSA had MIC of 2 µg/ml while 34/46(74.0%) of MSSA had MIC of 2 µg/ml. The prevalence of MRSA in nosocomial infections in ACH is 45.9%. Thirty-seven out of thirty-nine (94.9%) of the MRSA strains show high resistance to oxacillin (MIC > 256 µg/ml). The use of oxacillin-related drugs to treat nosocomial Staphylococcal infections in ACH should be reviewed and infection control practices should be intensified so as to stem any future increase in MRSA prevalence in the hospital.
Key words: MRSA, Characteristics, MICs, Vancomycin, Oxacillin.Afr. J. Clin. Exper. Microbiol. 2005; 6(2): 163-166

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Mycobacterium africanum – A Review

AO Onipede, B de Jong, RA Adegbola

 

Abstract

Tuberculosis, a curable infectious disease, remains the leading cause of adult death. The HIV/AIDS epidemic has greatly exacerbated the already grave situation in the developing world by creating a deadly synergy each worsening the course of the other. Mycobacterium africanumis a subspecies of Mycobacterium tuberculosis complex (MBC) and is isolated from tuberculous patients in certain parts of Africa. Genotypically, members of the MBC are closely related, exhibiting 99.9% similarity at the nucleotide level and identical 16s RNA gene (rDNA) and 16s-23s rDNA spacer sequences. However, identification and discrimination between members of the MBC are important for epidemiological purposes. This paper reviewed current knowledge about this subspecies.

Afr. J. Clin. Exper. Microbiol. 2005; 6(2): 167-175

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

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

 

Abstract

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

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

OA Daini, OD Ogbolu, A Ogunledun

 

Abstract

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

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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

 

Abstract

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

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

JN Abenga, K David, COG Ezebuiro, FAG Lawani

 

Abstract

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

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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

 

Abstract

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