(Erickson and Herzberg, 1999). Almost half o f these strains were found to be resistant to two or more antibiotics.
The resistance to antibiotics can occur by changing the target site on the bacteria (for example penicillin - binding protein o f S. pneumoniae) or by inactivation o f anti - microbials such as penicillinases or carbapenemases. In addition, the access o f antimicrobials can be prevented by the ability o f the organism to change its cell wall permeability or by an efflux mechanism that would pump out the antimicrobial agent (Wise, 1999).
A recent mechanism demonstrated that the genes o f the penicillin - binding protein 2B in a penicillin resistant S. pneumoniaewere actually originally from S. mitis. It has been suggested that genetic material can transfer between S. pneumoniaeand other viridans streptococci in particular S. mitis and S. oralis(Dowson et a l 1993).
1.6 Oral Focal Infection
Infection is a life threatening complication in renal transplant recipients taking immunosuppressive drugs (Greenberg and Cohen, 1977; Rubin and Tolkoff - Rubin, 1988; Naylor et a l 1988). In addition, the presence o f bacteraemia can be a cause o f further renal damage (Hobson, 1980). It is established that the majority o f the
micro - organisms that cause fatal complications in immunosuppressed patients may be found in the oral cavity (Greenberg and Cohen, 1977).
It has been reported that every day procedures such as tooth brushing can cause bacteraemia (Schafer et a l 1983; Naylor et a/.1988; Roberts et a l 1997; Lucas and Roberts, 2000). In addition, periodontal disease and poor oral hygiene were shown to increase the rate o f bacteraemia following tooth extractions and can cause bacteraemia even when no dental procedure is performed (Rahn et a l 1986; Bisno, 1981). Peripheral infection and teeth with infected root canals are also considered as a source o f bacteraemia. It was reported that bacteraemia could be produced by any dental procedure that causes bleeding (Bisno, 1981). Therefore, effective preventive care and the removal o f all foci o f infection in the mouth are essential (Naylor et a l
1988).
1.7 Summary
The spectrum o f renal problems associated with renal failure and renal
transplantation provides a series o f metabolic and oro - gingival changes. The majority o f the data available on children with renal problems is from short - term studies or studies looking separately at either the patients with CRF or RT.
Therefore detailed investigation o f the dental and microbiological changes in the patients with CRF while in the renal failure stage and after transplantation will provide an important and panoramic view o f the oral condition o f such a unique group o f children.
A further concern is the risk o f infection, which can be a life - threatening problem in transplant and immunocompromised patients. Therefore, identifying and
enumerating the main oral pathogens in this group o f patients could help in preventing clinical complications arising from the oral cavity. It could also
demonstrate the changes in the oral micro flora o f the children with CRF and children undergoing renal transplantation.
In addition, RT children are commonly given certain antibiotics for infections arising during the transplantation period or as an immediate post - transplant prophylactic measure. Therefore, testing the susceptibility o f the oral streptococci to the antibiotic commonly given is o f considerable importance to these children.
1.8 Null Hypotheses
1. The prevalence and incidence o f dental disease in children with chronic renal failure is not different from healthy children.
2. The oral microflora o f children with renal failure is not different from the oral microflora o f healthy children.
3. The dental health and oral microflora o f children undergoing renal transplant is not different from healthy children at baseline (before the transplant) and 90 days later.
4. The oral microflora is not different during the different stages o f transplantation, ju st before transplantation, soon after transplantation (before starting to eat) and
90 days after transplantation when a stable condition is achieved.
1.9 Aims and Objectives of the Project
The aim o f the project is to identify the dental and microbiological changes o f children with chronic renal failure and children undergoing renal transplantation.
Objectives:
1. To assess the prevalence o f dental caries, bacterial plaque, gingival inflammation, gingival enlargement and developmental enamel defects in children with CRF. 2. To investigate the salivary factors, urea and pH in children with CRF.
3. To identify and quantify the main oral micro-organisms, in particular, oral streptococci, lactobacilli, Candida species, enterococci, Enterobacteriaceae in children w ith CRF.
4. To identify the above variables in the renal transplant children. a. W ithin 12 hours before transplantation.
b. Within two days post - transplantation.
c. After an interval o f 90 days from transplantation.
5. To estimate the salivary urea and calcium levels and the saliva buffering capacity in children with CRF.
6. To compare these findings with matched healthy control children.
7. To assess susceptibility o f oral streptococci isolated from the renal transplant children at the 3 sampling times and from their matched controls on 2 separate
occasions 90 days apart, to the antibiotics commonly used to treat infection following renal transplantation.
1.10 Studies Conducted
Three main studies were carried out to meet the aims and objectives o f this project.