Relevance Of Blood Culture To The Diagnosis And Treatment Of Septicemia

Medical and Health Science Project and Seminar Material

Investigation Of UTI In Pregnancy


A study of septicaemia was conducted in Enugu metropolis with a view to determine the relevance of blood culture to the diagnosis and treatment of this disease. The subjects comprised of three hundred and fifty (350) children and adults of both sexes aged between one day to 70 years having clinical features suggestive of septicaemia, who were on admission at University Of Nigeria Teaching Hospitals (UNTH), Enugu. Their blood specimens were seeded into thioglycolateand glucose broths and incubated at 37 °C for 7 days. Subcultures were performed after 1, 2, 3, 4 and 7 days respectively. Growth (positivity) in the broths was assessed using conventional diagnostic methods namely macroscopy(visualization), Gram filming (microscopy) and culture. The bacterial isolates harvested were subjected to in-vitroantibiotic susceptibility tests using the disc diffusion method. Etiology was established in 104 out of 350 subjects indicating an incidence of 29.7%.

This difference in prevalence among different age groups was statistically significant(P < 0.01). The males (59/350, 16.86%) appeared to be more susceptible to septicaemia than the females (45/350, 12.9%) in all the age groups. This variation had no statistical significance (P > 0.01). Monomicrobialsepticaemia had ahigher prevalence (91.3%) than polymicrobialsepticaemia (8.65%). Staphylococcus aureusand Escherichia coliconstituted 33.3%. Most of the offensive microbes were facultative anaerobes (93.3%) while very few were strict aerobes (7.69%) and strict anaerobes (1.92%). The isolated anaerobes were Peptostreptococcussp. (1%) and Bacteroidesfragilis(1%). The in vitro susceptibility of the bacterial isolates to antibiotics indicated 78.9-92.9% sensitivity to vancomycin, zinnat, peflacin and fortum. However, they were 60 – 90% resistant to penicillin, ampicillin, tetracycline and septrin. This study confirmed the diverse nature of bacterial etiologies of septicaemia in Enugu metropolis; the need for the use ofthioglycolate broths, first subcultures on or before 24 h instead of starting off for after 48 h of incubation, complementary application of macroscopy, Gram filming and culture including antibiotic susceptibility test as an integral part of diagnosis and treatment of septicaemia is hereby advocated, most especially in the developing countries of the world.

Chapter One

1.0 Introduction

Blood is normally sterile in healthy individuals. It is the main transport mechanism connecting all different parts of the body. As it serves as a transport system for oxygen, food materials, waste products and others round the body, it can also carry microbes (Eugene et al., 1998). However, it has no normal flora and the presence of microorganism in it indicates failure of the defence mechanisms to maintain its sterility. In many cases such a failure is transitory and of no clinical importance but in others, it is serious and life threatening. Lymphoid tissue is an important part of the defence system acting as a filter to intercept potentially invasive pathogens as well as being the headquarter of the lymphocytes on which immunity is heavily dependent. This filter system is however liable to clinically significant infections by intercepted pathogen and it is also the primary target for some factors of infection (Douglas et al., 1981). The involvement of blood, lymphatic system and heart in many infections give us the knowledge of the presence of bacteria in the blood.

Various authors have reported bacteraemia immediately after incision of an abscess, tonsillectomy and tooth extraction (Fischer et al., 1941; Murry et al., 1941). Robert et al. (1997) described bacteraemia as a transitory disease in which bacteria present in the blood are usually eliminated from the vascular system by the reticulo endothelial system with no harmful effect, but in host with reduced immunity, septicaemia results.

The term septicaemia is often used in describing severebacteraemic infections or a condition in which the blood serves as a site of bacteria multiplication as well as a means of transfer of the infectious agent from one site to the other. The clinical picture frequently present in septicaemia is that of septic shock which is recognized by a severe febrile episode with chills, fever, malaise, tachycardia mental confusion, hyperventilation and toxicity, a hypotension (drop in blood pressure) and prostration which results when circulating bacteria multiply at a rate that exceeds their removal by phagocytes. Complications include disseminated intravascular coagulation (DIC) and acute renal failure (Shanson, 1999).

The mortality rate varies between 15 and 35%, depending on the age, the underlying condition and the treatment given (Shamson, 1998). Prompt recognition of septicaemia and immediate treatment based on the knowledge of the likely causative organism is essential. Septicemias which are of bacterial origin are caused by myriads of bacteria varying from one locality to another. Many studies on septicaemia in Nigeria have been on neonates and childhood and also retrospective (Dawodu et al., 1980) and there is therefore paucity of information on prospective study on septiceamia in different strata of society in Nigeria.

1.1 Blood Culture

Thisis a culture of blood microbiologically that is employed for the detection of diseases which are spreading through the bloodstream. One of such disease is septicemia. This culture of blood is possible because the bloodstream is usually a sterile environment and it is carried out through a laboratory test which will check for bacteria or other microorganisms in a blood sample. Most cultures check for bacteria. A culture may be done using a sample of blood, tissue, stool, urine, or other fluid from the body.

When signs or symptoms of a systemic infection is noticed in a patient, results from a blood culture can verify that an infection is present, and they can identify the type (or types) of microorganism that is responsible for the infection. A good example is when blood tests identifies the causative organisms in neonatal epiglottitis, sepsis, severe pneumonia, puerperal fever and fever of unknown origin (FUO). However, negative growths do not exclude infection. The usual risks of venipuncture and the occurrence of false positive results approximately 3%+ of the time, can lead to inappropriate treatment (Madeo et al., 2003).

1.2 Septicaemia

Septicaemia is often referred to as either blood poisoning, bacteremia or sepsis, although it could be argued that each of the terms are not entirely accurate, but are often used interchangeably by scientists (Al-Khafaji et al., 2010). Sepsis is not just limited to the blood and can affect the whole body, including the organs.

Septicaemia (another name for blood poisoning) refers to a bacterial infection of the blood, whereas sepsis can also be caused by viral or fungal infections.

Septicaemia also known as Sepsis is a condition that arises when the body’s response to infection injures its own tissues and organs (Deutschman and Tracey, 2014).Common signs and symptoms include fever, increased heart rate, increased breathing rate, and confusion. (CDC, 2014). There may also be symptoms related to a specific infection, such as a cough with pneumonia, or painful urination with a kidney infection. In the very young, old, and people with a weakened immune system, there may be no symptoms of a specific infection and the body temperature may be low or normal rather than high(Martí-Carvajal et al., 2012). Severe sepsis is sepsis causing poor organ function or insufficient blood flow. Insufficient blood flow may be evident by low blood pressure, high blood lactate, or low urine output. Septic shock is low blood pressure due to sepsis that does not improve after reasonable amounts of intravenous fluids are given (Dellinger et al., 2013).

Sepsis is caused by an immune response triggered by an infection (Jui, 2011; Deutschman and Tracey, 2014). The infection is most commonly bacterial, but it can also be from fungi, viruses, or parasites (Jui, 2011) Common locations for the primary infection include: lungs, brain, urinary tract, skin, andabdominal organs. Risk factors include young or old age, a weakened immune system from conditions such as cancer or diabetes, and major trauma or burns (CDC, 2014). Diagnosis is based on meeting at least two systemic inflammatory response syndrome (SIRS) criteria due to a presumed infection. Blood cultures are recommended preferably before antibiotics are started; however, infection of the blood is not required for the diagnosis (Jui, 2011). Medical imaging should be done to look for the possible location of infection (Patel and Balk, 2012). Other potential causes of similar signs and symptoms include: anaphylaxis, adrenal insufficiency, low blood volume, heart failure, andpulmonary embolism among others (Jui, 2011).

1.3 Objectives of the Research

This objectives of this research are to;

  1. Determine the relevance of blood culture to the diagnosis and treatment of septicaemia.
  2. Compare the occurrence of Gram positive and Gram negative bacteria in the subjects with culture – proven septicaemia.
  3. Determine which gender(male or female) is more prone to septicaemia.

1.4 Justification

It is important to ensure that bloodstream infections are diagnosed accurately and that infecting pathogens, their antimicrobial susceptibilities, and the possible primary sources of infection are evaluated thoroughly, to enable optimal targeted antimicrobial therapy. Blood cultures and their microbiological analysis are highly essential and important for the diagnosis and treatment of septicaemia (sepsis).Blood culture is important for early diagnosis and treatment of patients with septicaemia as survival depends on early detection and administration of adequate empirical antimicrobial therapy.

Chapter Five

Discussion of Finding and Conclusion


The findings of this study revealed that Septicemia still remains the major killer disease in Nigeria (Eugene, 1998). Although its incidence of 31.4% found in this study is higher than the 26% reported by Akuse et al. in 1984 at Ibadan among the neonates, it fell within the range of 15- 35% reported by Shanson in 1999. This study has established that the disease affects all age groups but it was noticeable that neonates, children and teenagers were more vulnerable than adults as persons between years of 0-20 years were most infected. This vulnerability was most prominent, pronounced and apparent among the neonates because they accounted for the majority (16.2%) of the patients that had culture–proven septiceamia in this study. It was observed that septicaemia was most prevalent in the first week of life and reduced remarkably with age increase (Table 1). This difference in age distribution of the infection was statistically significant (P< O). The higher occurrence in childhood septicaemia has been reported from different parts of Nigeria (Akuse et al., 1998; Akpede et al., 1996, Ako-Nai et al., 1999, Angyo et al., 2001; Owa et al., 1988; Olusanya et al., 1991). The high occurrence of neonatal septiceamia in Ile-Ife may probably be adduced to their low immune response, socio-economic status of the parents, poor hygiene practices, bottle feeding and high incidence of delivery at home. An additional effect of their low socio-economic status is exhibited by the inability of their parents to pay the hospital fees charged for delivery; consequently they deliver at home, churches, maternity centre or herbalist shrines where there are no proper midwifery facilities. Infections of neonates may be due to contamination as a result of poor hospital hygiene and inadequate hand – washing by staff, impairment of host principal effect of low socio-economic status is the inability of the indigent mothers to maintain successful lactation as it is necessary for the mother to be mentally and physically healthy (Beischer et al., 1979).

There was no statistically significant difference in gender variation in septicaemia, it is interesting to notice that males has a higher prevalence level than the females, though this slight variation has been previously documented by various authors (Bnetow, 1965; Behrman 1977). This higher prevalence in male may be adduced to exposure factors and peculiar behavioural attitudes/activities of them which make them more prone to accidents. This reason cannot be advanced to higher occurrence of neonatal septiceamia in males than females. Although no author has proffered any reason for this, it may be ascribed to genetic basis.

It is noteworthy that Gram positive organisms were more predominant than Gram negative ones. This is contrary to the earlier reports by Owa et al. (1988) at Wesley Guild Hospital, Ilesa, Alausa et al. 1984 at Ibadan and Dawodu et al. (1980) but conforms with those of Antia–Obong et al. (1990), Njokanma et al. (1990), Olusanya et al (1991) Ako-Nai et al. (1999) and Angyo et al. (2001). Of the Gram–positive bacteria, the three common microbes were S. aureus, S. albus and Streptococcus faecalis among which Staphylococcus aureus had the highest occurrence while Klebsiella sp. was the most predominant among the Gram negative bacteria, followed by E. coli and Pseudomonas sp. However, the four most common microbes isolated from blood cultures in this study were S. aureus, Klebsiella sp.,
E. coli and S. albus respectively in descending order. S. aureus was still the leading cause of Septicemia. This observation is in agreement with the work of some authors (Owa et al., 1988; Alausa et al., 1984; Olusanya et al., 1991; Ayliffe et al., 1977; Ako–Nai et al., 1999) but deviates from the reports from some hospitals from undeveloped countries by some authors. Gorbach and his colleagues (1992) reported that E. coli was the preponderant microbe. The occurrence of Klebsiella sp. in this study is in tandem with the findings of Olusanya et al. (1991), Ako-Nail et al. (1999) and Angyo et al. (2001) in Nigeria but at a wide variance with that of Ghanshyam et al (2002) in India. This work further revealed that there is drastic reduction in the incidence of septicaemia due to anaerobes in this 20th century which is contrary to the report of several authors (Stoke, 1958) about four decades 19th century. This observation was in similitudes of discovery of Mandell and colleagues (1995). The decline of detectable anaerobic septicaemia in many hospitals may be advanced to the wide spread use of antibiotics active against them especially in surgical prophylaxis. The significance of anaerobes in septicaemia has been explicitly demonstrated by Chow et al. (1994). The preponderance of facultative anaerobes in the blood cultures in this work which is completely in conformity with earlier reports of other authors (Shanson et al., 1999; Eugene et al., 1998) may be related to their defences and instrumentation and surgery. The other ability to live and survive in both anaerobic and anaerobic environment.

It has also been demonstrated in this study that most of the septicaemic episodes were caused by a single organism (Monomicrobe) while polymicrobial aetiology was observed in only a few cases. This observation is in consonance with earlier reports (Bartlett et al., 1974; Ghanshyam et al., 2002; Angyo et al., 2001). In Indian reports, polymicrobial aetiology was documented in 8% of cases by Thomas et al. (1999) and 6.8% in another study by Ghanshyam et al. (2001) which are very similar to the incidence of 7.8% in this study. A western study reported an incidence of 3.9% of polymicrobial sepsis. Comparatively, this indicates that incidence of polymicrobial sepsis in developing countries is higher than in developed countries of the world. The decrease in incidence of septicaemia in developed countries may be due to proper sanitation which has successfully diminished the infection in more affluent regions of the world. Most clinical bacteriologists failed to report polymicrobial sepsis because of misconception of contamination, ignorance of its significance or disregard for the second organism in an already positive culture (Sharma et al., 1987; Mathur et al., 1994; Mondal et al., 1991). However, there is a need to correlate the occurrence of polymicrobial sepsis with clinical outcome in septicaemia. A patient already infected with one microbe may have acquired the second one from the hospital environment or both the bacteria could be nosocomial in origin.

A study of in vitro antimicrobial susceptibility profile of the aetiological agents of septicaemia has revealed that there is a growing emergence of multi-drug resistant microbes. Forty six percent (46%) of S. aureus isolated were resistant to cloxacillin which is a drug often used for initial and empirical treatment of Staphylococcal infections. This high level of resistance to cloxacillin may pose problems in the treatment of staphylococcal septiceamia. The increasing resistance of S. aureus to cloxacillin, 46% observed as against 40% documented by Angyo et al. (2002) may be due to the widespread abuse of the drug which is usually available in combinations with ampicillin for the treatment of infections in our society and can be obtained over the counter without a prescription. About seventy to ninety percent (70 – 90%) of S. aureus isolates were resistant to other commonly used antibiotics like penicillin, ampicllin, tetracyline and cotrimoxazole. The consequences of using an ineffective drug in severe bacterial infections could be disastrous as this can complicate management and increase morbidity and mortality.

Nevertheless, it is interesting to observe that most of the organisms were sensitive to gentamycin, fortum, rocephin, zinnacef, peflacin and vancomycin respectively. Therefore, as gentamiyin and vancomycin are still effective, they can be prescribed for the initial and empirical treatment of septicaemia in our environment pending culture and sensitivity reports.

Although the sensitivity of the organism isolated to the third generation cephalosporin was generally excellent in the present study, the high cost of this group of drugs precludes their use as first choice in the treatment of septicaemia.


A general overview of the antibiogram of all the bacterial isolates indicates that Gram negative bacteria exhibited a greater level of antimicrobial susceptibility (ranging between 19.8% – 92.3%) than Gram positive bacteria (10% – 87%) to various antibacterial agents employed during the study period. This situation raises serious concern. This suggests a very high resistance gene pool due perhaps to gross misuse and inappropriate usage of the antibacterial agents.

The upsurge in the antibiotic resistance noticed in this study is in agreement with an earlier report by Obseiki-Ebor et al. 1987 where antibiotic abuse and high prevalence of self medication with antibiotics were identified as being responsible for the selection of antibiotic resistant bacterial strains. This piece of work has demonstrated vividly the urgent need for management strategies designed for specific groups of patients with infections in order to maximize therapeutic benefits, cost reduction and possible reduction in the incidence of adverse drug reactions. There is therefore need for usage policy that would be made applicable to the different tiers of our health care providers at the primary, secondary and tertiary levels. This can be done concurrently with sustained enlightenment and media publicity focusing attention on the dangers of high incidence of bacterial resistance to antibacterial agents in general and the ultimate consequences.

Finally, an assessment of the three traditional methods, namely visual inspection (Microscopy), Gram filming and culture for detecting positive blood culture has shown that the latter was the most sensitive, reliable and reproducible. Apart from the identification of the aetiological agents, the antibiogram can also be determined. It can detect some organisms that fail to produce sufficient turbidity to be detected by visual inspection at an early stage of incubation. It also facilitates the early diagnosis of polymicrobial infection and precise judgment/ruling out of suspected contamination of the specimen. Living bacteria could be isolated and distinguished from dead organism. The sensitivity of Gram stain is very close to that of macroscopic (visual) examination (21.2% and 25.4% respectively). This is in tandem to results found by Freeman in 1990. Macroscopic and Gram filming could be adopted for use in rural laboratories that have no culture facilities. Both methods obviate the need for blind subculture and they might be employed as simple sensitive screening method for early detection of organisms in blood streams (Mirret et al., 1982).

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