The Menace of Typhoid / Paratyphoid Fever – The Abuja Experience: A 5 Year Retrospective Study

摘要

Typhoid / paratyphoid fever is caused by Salmonella typhi and Salmonella paratyphi A, B and C respectively. A 5 year retrospective study on blood (Oxoid signal blood culture system) and faecal cultures at the Medical Microbiology Laboratory of National Hospital, Abuja was carried out. Of the 2,818 blood cultures, only 90 (3.2%) had positive cultures for Salmonella species while the 10,007 faecal samples cultured, only 159 (1.58%) were positive for Salmonella species. Identification was by biochemical and serological methods. The sensitivity pattern in both blood and faecal isolates show Ceftazidime (97.9% and 98.1%), Ceftriaxone (98.0% and 95.4%), Cefotaxime (97.6% and 93.7%), Gentamicin (80.9% and 78.5%), Augmentin (76.1% and 69.5%), Amoxycillin (45.5% and 56.4%), Chloramphenicol (40.6% and 75.2%), Tetracycline (100% and 51.1%), Ampicillin (35.3% and 32.6%) and Cotrimoxazole (34.4% and 76.6%). Our results indicate a very low rate of typhoid / paratyphoid fever and the need for isolation and proper sensitivity testing before the commencement of therapy. Appropriate specimens (faeces, urine, or blood) from suspected patients should be cultured for the presence of salmonellae. Introduction Typhoid / paratyphoid fever is caused by Salmonella typhi and Salmonella paratyphi A, B and C respectively. It is customary in our society that any feverish condition is first treated for malaria. If this fails, then treatment for typhoid automatically follows and if the patient at this stage fails to respond, it is only then that laboratory investigations are remembered(1). Salmonellosis is responsible for a variety of clinical syndromes, including gastroenteritis, enteric (typhoid) fever and extraintestinal manifestations.Typhoid fever remains one of the most prevalent acute infectious diseases in the developing world including Nigeria. It continues to exist as an endemic disease due to poor (improper) sanitation and low socio-economic status of the people(1). The Widal test (Widal’s agglutination reaction) is routinely employed for the serodiagnosis of typhoid fever by most Medical Laboratories in Nigeria. However, several workers within the Medical community have expressed doubt regarding the reliability of the test. There are several contributing factors for this uncertainty. Some have started calling for the discontinuance of Widal test as a diagnostic test for typhoid fever. Their argument is based on;1. The difficulty of interpreting Widal test result in areas where typhoid fever is endemic and where the baseline titre of the normal population are not known.2. The typhoid febrile agglutination test (Widal test) is often positive (raised O and H titres) in patients with infections caused by other bacteria, because of cross-reacting antibodies or previous vaccination with TAB or typhoid vaccine; chronic liver disease associated with raised globulin levels, and disorders such as rheumatoid arthritis, rheumatic fever, multiple myeloma, nephrotic syndrome, and ulcerative colitis.3. The differential behavioural pattern of isolates of Salmonella species to various antibiotics as seen from our susceptibility test results.The aim of this work therefore is to re-emphasize the importance of using appropriate specimens (faeces, urine and blood) in the laboratory diagnosis of Salmonella species and its antimicrobial susceptibility pattern prior to treatment for typhoid / paratyphoid fever. Materials And Methods A 5-year retrospective study on blood (Oxoid Signal blood culture system) and faecal cultures at the Medical Microbiology Laboratory of National Hospital, Abuja was carried out.Blood CultureThe Oxoid Signal Blood Culture System (produced by Oxoid Limited, Wade Road, Basingstoke, Hampshire, RG24 8PW, England) was used to culture samples of blood collected from patients where the condition of bacteriaemia is suspected.