Bacteriology Laboratory Performance Index in Childhood Septicaemia

S. Kolade Ernest; SK Babatunde; BA Adegboro

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S. Kolade Ernest¹, SK Babatunde², BA Adegboro².

¹Department of Paediatrics Child Health, University of Ilorin, Ilorin,
²Medical Microbiology Parasitology, University of Ilorin, Ilorin.

ADDRESS FOR CORRESPONDENCE
S. Kolade Ernest, Dept. of Pediatrics, University of Ilorin Teaching Hospital, PMB 1459, Ilorin. Nigeria.
Email: kolade.ernest@yahoo.com

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Keywords

Childhood septicaemia, Bacterial isolation, Laboratory Performance Index

Introduction

Infectious disease is one of the leading causes of morbidity and mortality in most developing countries. Bacterial infections is one of the most acute and life-threatening infections requiring meticulous diagnosis and treatment.(1,2) Culturing the blood to isolate the bacterial agents of septicaemia in any patients is one of the most important confirmatory procedures in our Laboratories3. Blood cultures should be done carefully before empirical antibiotics are administered to patients.

Bacterial killing is the ultimate goal in the use of antibiotics. To achieve this, the understanding of the causative agents of septicaemia must be known so that appropriate choice of antibiotics could be made. Hence, blood culture remains central to this quest for identifying bacterial causes of septicaemia4. Even though several other methods for detection of bacterial agents exist, centers in the developing countries and even several health centers in the developed nations, depend heavily on the isolation of bacterial agents through blood cultures. However, due to poor laboratory techniques, poor laboratory conditions, underdeveloped human skills, the wide-spread abuse of antibiotics that were not prescribed by qualified physicians, the rate of growth of bacterial agents rarely exceed 40-50% growth yield in most laboratories5. Where the bacterial growth rate in blood cultures is remarkably low then the resources invested in such laboratory and its outcomes need evaluations. Such evaluation will help determine if the outcome results justify the input investment and this will guide health planners either to invest more resources that may lead to an exponential output that we dearly need in the developing countries. We therefore, conducted an audit and evaluated the blood culture growth yield of our microbiology laboratory with a view to assessing its efficiency for future improvement.

Methods and materials: All patients, 14 years and below with suspicion for septicaemia in the University of Ilorin Teaching Hospital, Ilorin within 3 consecutive years (Jan 1997-Dec 1999) had blood drawn and sent to the Microbiology Laboratory for culture to identify bacterial agent responsible for the illness. Seventy percent (70%) alcohol was used to disinfect the skin of patients before samples were taken in a culture bottle containing between 50 to 100ml of broth for aerobic and anaerobic cultures. This was incubated at 37°C. Wherever there were evidences of bacterial growth, sub-culturing on blood agar and MacConkey plates after the first 24 hours was done. Both plates were respectively incubated aerobically and anaerobically for 7 day. Plates were then discarded afterwards if there were no growth. Where there was growth, isolates identification was done in a standard way6 . Laboratory records were examined to extract necessary information for this study.

Results

The age of patients under review were < 14 years. However, under 5 years old children (<59 months) constitutes 72.4% of the total. The Male to Female ratio was 1.4:1 (Table I). More than one half (1377-56.6%) of all the blood samples came from the Emergency Paediatric Unit (EPU) of the hospital the rest were sent in from Neonatal Intensive Care Unit ( 577 - 23.6%), Children's ward (263 - 10.9%) and the General Out-patient Department (218 - 8.9%). Approximately 24% (582) of the blood culture plates grew a pathogen within the 7days of cultures. Contaminants were grown in 208 (8.5%) samples while the rest 1645 (67.6%) grew no organisms.

TABLE I: Distribution of Patients by Sex and Age

Distribution of patients	No (%)
Sex Male Female	1409 (57.9) 1026 (42.1)
Age < 28day < 28-11months 12months -59months 60-119months 120-168 months	602 (24.7) 375 (15.4) 788 (32.3) 336 (13.8) 334 (13.8)

Majority of the grown bacteria were gram positive, constituting 60.4% while gram negative constituted 39.6%. Staphylococcus aureus was the leading gram positive isolate and constituted about a third of all the pathogens isolated. Atypical coliforms were leading gram negative pathogens isolated and constituted 18.8% of all the pathogens isolated (Table 2).

Table 2: Bacterial Agents Isolated from 2435 blood samples of septicaemia children

Isolates	No	(%)
Staphylococcus aureus	191	32.9
Staphylococcus epidermidits	105	18.1
Coliforms (atypical)	109	18.8
Klebsiella Pneumonia	51	8.8
Streptococcus faecalis	46	7.9
Salmonella Spp.	28	4.9
Escherichia Coli	33	5.7
Pseudomonas auruginosa	5	0.9
Acenetobacter Spp	3	0.5
Protens mirabilis	3	0.5
Non-haemoly tic streptococci Spp	2	0.3
Streptococcus pneumonia	2	0.3
Streptococcus viridans	1	0.1
Micrococcus	1	0.1
Serratia Spp.	1	0.1
Cetrobacter	1	0.1
Total	582	100

Discussion

Majority of the paediatric patients with septicaemia were under 5 year old children. This agrees with finding in other center and also establishes the predisposition of that age group to infections4. Our series also showed male preponderance. Males may be more susceptible to infections because of their possession of a single X-chromosome thought to contain the gene which regulates the synthesis of immunoglobulins. Rhodes et al had earlier reported significantly higher IgM levels in patients with XXX-chromosomes compared with patients with XX-chromosomes (p<0.01) and also in patients with XX-chromosome compared to patients with XY-chromosome (p < 0.05).(7,8)

More than one half of the samples came from the Emergency Paediatrics Unit, (EPU), this is not surprising because almost allpaediatrics patients above neonatal age with acute illnesses are brought to the EPU for evaluations.

The culture yield rate, which measures the laboratory efficiency, was low at approximately 24%. This is remarkably lower than reports from other local center and laboratories from other nations of the world.(4,9) The low yield of blood culture may be due to inadequate funding that has affected laboratory environment and performance, inadequate staffing, delay in getting samples to the laboratory by patients due to delay in payment of appropriate hospital charges and delay in treatment of samples brought to the laboratory. The rate of negative culture outcome is unreasonably high. Again this may just be validating the unchecked and wide-spread use of antibiotics without prescription by physician. Many a times antibiotics, doses are either insufficient, inadequate and or inappropriate. Such antibiotic abuses affect laboratory growth of bacterial agents. Also it may reflect poor laboratory techniques. The rate of isolation of contaminants at just less than 10% was high. This may reflect a poor blood sampling techniques. It was difficult if the skin was appropriately disinfected with 70% alcohol. This could not be assured as suboptimal consentration of alcohol were been sold around that time. Traditionally, most samples were taken by the least cadre of doctors (the House Officers) and occasionally medical students took some samples in attempt to learn the venipucture skills. This category of doctors do not possess satisfactory skill that ensures satisfactory sampling of blood. Also, for lack of materials a second needle might not have been used to transfer the blood sampled into the culture bottles. So the needles used to pierce the improperly disinfected skin were also used to transfer samples into the culture bottles. Also, sub-culturing techniques and laboratory behaviours such as laminar flow and minimal air and human movement within the laboratory environments might have been jettisoned.(10)

The commonest cause of septicaemia in our series was staphyloccocus aureus which was a third of all the isolates. This correlates with previous reports from our center and elsewhere.(11,12) In 1985, Salmonella spp. was the commonest isolated cause of septicaemia in this same laboratory, but is the sixth in this series. The presence of health awareness, better treatment of public drinking water might be few of the factors responsible for the reduction in the prevalence of salmonella spp. causing septicaemic illness in the paediatric age groups.(13) Staphyloccocus epidermidis was second leading cause of sepsis in this series. This used to be considered insignificant before but in the advent of increased immunocompromised status in some children and immuno-incompetence in neonates the organism must become a focus for control.

We concluded therefore that the efficiency of our laboratory is low and need urgent improvement so that aetiological diagnosis may be possible for infectious illnesses affecting children. It is suggested that doctors responsible for sampling blood for cultures should be properly oriented before such important part of patient care is left as part of their responsibilities.

Compliance with Ethical Standards

Funding None

Conflict of Interest None

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