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A prospective study was undertaken to determine the frequency of various pathogens causing postoperative septicemia with their antibiotic resistance pattern in surgical ward patients from rural area.
Methods: A study of postoperative septicemia was carried out over a two year period. Blood samples from sixty two patients were cultured using standard bacteriological techniques. Organisms were isolated and identified by biphasic method (BHIA-BHIB).Antimicrobial susceptibility for each isolate was done by using Kirby Bauer disc diffusion method.
Results: Out of sixty two patients, blood culture was positive in 38(61.29%).The commonest causative organisms isolated were Staphylococcus aureus ( 31.58%), followed by Klebsiella aerogenes(26.31 %), Pseudomonas aeruginosa ( 15.79%), E.coli (10.53 %), Proteus species (5.26 %), Staph.Albus(5.26%) and Streptococcus pyogenes(5.26%). Gram negative organisms were the most predominant isolates. Majority of the isolates were sensitive to Ciprofloxacin.
KEYWORDS: postoperative septicemia, rural area, blood culture, antibiotic resistance, Staphylococcus aureus
Postoperative septicemia continues to be a major source of morbidity and mortality in surgical patients. Wound septicemia is the third most commonly reported Nosocomial infection and they account for approximately a quarter of all Nosocomial infections.1
Postoperative septicemia has been responsible for the major problem even in hospital with most modern facilities and standard protocols of preoperative preparation and antibiotic prophylaxis.2 Postoperative sepsis may be responsible for the failure of an operation, septicemia and also results in tremendous loss of time and money due to prolonged period of healing. The main determinants of infection are the microorganism, the environment and the host defense mechanism. There is continuous interaction between these three factors.
We therefore considered it necessary to Obtain bacteriological diagnosis and antibiotic resistance pattern in surgical wards before starting antimicrobial therapy. It will be of paramount importance for the successful therapy of postoperative septicemia. It would reduce mortality from septicemia and improve patient management.
With this background the present study was undertaken to know the bacteriological profile of postoperative septicemia and their antibiotic resistance pattern in surgical wards from rural area surrounding a rural medical college and hospital.
The present study was carried out in department of Microbiology over the period of two years. Sixty two patients of postoperative septicemia admitted in surgical wards of rural hospital who underwent either emergency or elective operation were included in the study. All clinically diagnosed cases of postoperative septicemia were subjected to blood culture studies. Blood culture was performed by biphasic method (brain heart infusion agar and broth).3, 4 The study was approved by institutional ethical committee. Blood samples were collected under all aseptic precautions by venepuncture. 5 ml of blood was withdrawn from the patients. Blood sample was collected before starting antimicrobial therapy. In patients already on antibiotic therapy, blood sample was taken just before the next dose of antimicrobial agents. In all cases only a single blood sample was collected (one sample per patient). 3, 4
The inoculated BHIA-BHIB bottles were incubated at 37oC and kept in vertical position. The bottles were observed twice a day and if there was no growth, subculture performed by tilting the bottles so that blood broth flows over the slant. The bottle was again incubated in vertical position.
Growth was made out by turbidity, hemolysis, gas production and formation of discrete colonies on the slant of biphasic medium.
If growth was seen on agar slope, colony morphology was noted and identified by its characters. If turbidity, hemolysis or gas production was seen, bottle was opened with due precaution and a loopful of broth was taken and subculture was done on blood agar plate and MacConkey agar plate. In case of discrete colonies on the slant, colony was picked up, Gram stained smear was prepared and subculture was done on blood agar plate and MacConkey agar plate. 5, 6
After Gram stain information, colony was inoculated in nutrient broth for Gram-positive organisms and in peptone water for Gramââ‚¬"negative organisms. Biochemical reactions were studied.7 If there was no growth on culture bottles upto 10 days then they were discarded. All the isolates were identified by standard biochemical tests. Antimicrobial susceptibility testing was performed on the isolates by standard conventional (Kirby-Bauer) disc diffusion method.8
RESULTS AND DISCUSSION
Table No. 1 shows the various bacterial isolates in postoperative septicemia: Staphylococcus aureus was isolated as the commonest pathogen in 12 cases of postoperative septicemia followed by Klebsiella aerogenes (26.31 %), and Pseudomonas aeruginosa (15.79 %).
Table No. 2 shows antibiotic resistance pattern of isolates: Most of the Staphylococcus aureus isolates were resistance to penicillin. Pseudomonas aeruginosa shows 100% resistance to Gentamicin. All Gram negative isolates were resistant to co-trimoxazole and ampicillin.
The postoperative septicemia rate reported by different workers varies from 9.2%9 to 81%. 10 The overall postoperative septicemia rate in present study was 61.29%.Whereas in other study postoperative septicemia rate was 52.6%.11
Maximum numbers of patients were in the age group of 25-45 years. Female patients were more as compared to males. As more cases were post tubectomy septicemia or may be due to obesity, malnutrition or evidence of remote infection.
Blood culture is the essential investigation for the management of postoperative septicemia. Blood culture is considered as positive when it showed the growth of one or two organisms. The data obtained from positive blood culture was often helpful in changing empirical therapy. Therefore blood cultures remain important diagnostic tools.12 Various organisms can cause postoperative septicemia. The frequency of infection by various organisms varies from one hospital to another and even from year to year in the same hospital.13
In the present study, Staphylococcus aureus was isolated as the commonest pathogen. The overall incidence of Gram negative bacilli was 57.89 %. Gram negative bacilli have also been reported as the most common causative organisms by other workers.14,15Most common Gram negative bacilli was Klebsiella aerogenes (10) followed by Pseudomonas aeruginosa (6), Escherichia coli isolated from four cases and Proteus species from three cases. Other Gram positive cocci isolated were Staphylococcus albus from two cases and Streptococcus pyogenes from two cases of postoperative septicemia.
In this study out of 61.29% isolates, Gram negative organisms were predominant (57.89%) followed by Gram positive organisms (42.10%). The ratio of Gram positive to Gram negative organism was 1:1.37.
The main observation in this study was the higher isolation of Staphylococcus aureus (31.58%). This was similar to the findings of other workers. Predominant isolation of Staphylococcus aureus was reported by Mangram AJ, Olson MM, Prabhakar H, Fowler VG Jr and K Twum- Danso.1, 16, 17, 18, 19 Among Gram negative bacilli, Klebsiella (26.31%) was the commonest isolate in the present study but in other study E.coli was the commonest Gram negative bacilli.20 This high incidence of Gram negative bacilli could be due to large number of postoperative septicemia developed following abdominal surgery.
Literature suggests that there is gradual increase in the emergence of resistant microorganisms in surgical patients.21,22,23 The treatment guidelines are decided on the basis of either sensitivity or resistance pattern of bacteria tested with a given antimicrobial that vary geographically. Antimicrobial sensitivity pattern of all the isolates were studied by Kirby- Bauer disk susceptibility testing. In the present study, most of the Staphylococcus aureus isolates were resistance to penicillin. This was also reported by other workers.21, 22, 23 Pseudomonas aeruginosa shows 100% resistance to Gentamicin. This was one of the antibiotics used for antibiotic prophylaxis. All Gram negative isolates were resistant to co-trimoxazole and ampicillin. Cephalexin, ciprofloxacin and erythromycin showed greater sensitivity against Gram positive isolates. Ciprofloxacin and amikacin showed high sensitivity against Gram negative isolates.
Pseudomonas aeruginosa is one of the most virulent organisms which cause problems clinically as a result of its high resistance to antimicrobial agents. In the present study Pseudomonas aeruginosa showed high sensitivity to ciprofloxacin (93.34%) followed by amikacin (66.66%). In this study ciprofloxacin was found to be the most effective antipseudomonal agent.
There has been tremendous change in the bacterial flora of postoperative septicemia. Many workers have reported increasing prevalence of antibiotic resistant strains of Staphylococcus aureus, Pseudomonas aeruginosa and other bacteria which may form part of patientââ‚¬â„¢s endogenous flora or may be present in other patients and hospital environment.14, 24
The present study shows that the rate of postoperative septicemia is high in this area. Although Staph. aureus was the most common isolate, Gram negative bacilli were being isolated at higher rate.
As the organisms most frequently isolated in postoperative septicemia changes from time to time. Previously most frequent and feared pathogen was Streptococcus. Twenty years ago Staph.aureus was principle offender. Later on it was changed to Gram negative bacilli. Staphylococcus aureus has now replaced Gram negative bacilli. The present study also shows reemergence of Staph.aureus as the principal offender responsible for postoperative septicemia.
The changing bacteriological pattern of postoperative septicemia warrants the need for an ongoing review of the causative organisms and their antibiotic sensitivity pattern. Area based knowledge of the bacteriological spectrum is essential and keeping in mind the high morbidity and mortality associated with sepsis, a right choice for such empiric therapy is of utmost importance.
Conflict of interest- None to declare
The author thanks Dr. B. S. Nagoba, assistant Dean, MIMSR Medical College, Latur and Dr. S. B. Tamboli, Associate professor and Head, Dept. of Pharmacology, Dr. Shankarrao Chavan Govt. Medical College, Nanded (Maharashtra) for their invaluable advice and help with the manuscript.