N Ibecheozor, I Peletiri, J Ajobiewe, N Akogwu, P Onyeka, A Ogundeji, W Okoye
antibiotic susceptibility pattern., blood, faecal cultures, salmonella species
N Ibecheozor, I Peletiri, J Ajobiewe, N Akogwu, P Onyeka, A Ogundeji, W Okoye. The Menace of Typhoid / Paratyphoid Fever – The Abuja Experience: A 5 Year Retrospective Study. The Internet Journal of Microbiology. 2012 Volume 10 Number 1.
Typhoid / paratyphoid fever is caused by
Typhoid / paratyphoid fever is caused by
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
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
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.
The 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.
Procedure for Blood Culture
ml of blood is inoculated into Oxoid Signal Blood Culture System. This is a semi-automated system that recognizes bacterial growth in the blood culture by gas production. The inoculated bottle is placed at 36oC (+/-) 1oC for 1 hour before inserting the Signal device. It is continuously shaken for 24 hours. Incubate at 360C (+/-) 1oC for at least 7 days.
A positive bottle is indicated by upward movement of fluid into the signal device while a negative bottle is indicated by absence of fluid in the signal device.
All positive bottles are sub cultured onto Chocolate agar, 3 Blood agar and MacConkey agar plates and incubated for 24 hours at 36 (+/-) 1oC. When applicable, it is re-incubated for a further 18 – 24 hours. The second Blood agar plate is incubated at 10% CO2 while the third Blood agar plate is incubated anaerobically (AnO2) for 48 hours.
Isolates are identified by gram stain, biochemical reactions (Kliegar Iron Agar – KIA, Urea, Citrate, MRVP) as well as sero-typing using
Antibiotic susceptibility test (disc diffusion technique) is carried out on isolates.
Procedure for Faecal Cultures
Faecal samples were cultured on Salmonella /Shigella Agar (SSA) or Deoxycholate Citrate Agar (DCA) and Selanite Fluid (SF) and incubated at 37oC for 18 – 24 hours. The Selanite fluid preparation is sub cultured on SSA or DCA and further incubated at 37oC for 18 – 24 hours.
Non Lactose Fermenting Colonies (NLFs) isolated are subjected to identification as stated above under the blood culture methodology.
Of the 2,818 blood cultures, only 90 (3.2 %) had positive cultures for
Antibiotic Susceptibility Testing of Blood and Faecal isolates
Ten (10) antibiotic discs were used for the susceptibility testing. Viz; Amoxycillin, Ampicillin, Augmentin, Cefotaxime, Ceftazidime, Ceftriaxone, Chloramphenicol, Cotrimoxazole, Gentamicin, and Tetracycline.
Note:Only six (6) antibiotic discs are used for testing at any given time!
Of the 10,007 faecal samples cultured, only 159 (1.58%) had positive cultures for
Of the 2,818 blood cultures, only 90 (3.2%) had positive cultures for
In 1995, Oboegbulam
The sensitivity pattern in both blood and stool 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%), Cotrimoxazole (34.4% and 76.6%) and Ampicillin (35.3% and 32.6%).
The wide variation of susceptibility pattern in blood and faecal isolates for Chloramphenicol, Tetracycline and Cotrimoxazole cannot be explained.
Our results indicate a very low rate of typhoid / paratyphoid fever amidst varying susceptibility pattern of antibiotics to the isolates. The use of Widal agglutination test as a basis for diagnosing typhoid / paratyphoid fever and treatment of same based on a high titre value will definitely lead to drug misuse, emergence of drug resistant strains, as well as complications. Bacterial agglutination tests are often used to diagnose diseases in which the bacterial agent is difficult to cultivate in-vitro.
Agglutination tests for certain diseases such as typhoid fever have become less useful with the ability of most laboratories to cultivate and identify the causative agent. The typhoid febrile agglutination test (Widal test) is often positive in patients with infections caused by other bacteria, because of cross-reacting antibodies or previous immunization (vaccination) against typhoid. Appropriate specimens (stool, urine, or blood,) from suspected patients should therefore be cultured for the presence of salmonellae.