Incidence  of  Surgical  Site  Infections  and Microbial Pattern at Kilimanjaro Christian Medical Centre

Kitembo SK.K2,32,3MD(UDSM),ChuguluSG.G1,21,2MD,MD,MMed,FCS(ECSA).

1-Kilimanjaro Christian Medical Centre

2-Kilimanjaro Christian Medical College

3-Muhimbili National Hospital

Correspondence to: Dr. Kitembo S.K P.O Box 31159, Dar es Salaam, Tanzania.




Surgical site infection (SSI) remains a major cause of morbidity and death. We conducted a study to determine the incidence of surgical site infections and microbial pattern at Kilimanjaro Christian Medical Centre.


Patients and Methods

A prospective hospital based study was conducted at KCMC general surgical wards from November, 2010 to March, 2011. A total of 263 newly operated inpatients were enrolled but 27 patients among the group were lost on follow up visits and were therefore excluded from the study. So, only 236 patients completed the study’s one month follow up.


Two hundred and thirty six patients were followed up for the development of surgical site calinfectsiteionnfect.Eighteen.18 patients developed features of surgical site inffection.. Four patients had culture negative results.. One patientt who developed SSI due to an infected implant died.. Superficial SSIs constituted (61.1%) while deep SSI constituted (27.8%) and organ/space (11..1%).. The overall SSI rate was 7.6%. Clean,, clean contaminated,, contaminated and dirty wounds had infection rates of 3.5%, 8.7%, 25..4% and 29..4% respectively.. There were 15 bacterial isolates and multidrug resistance was also observed in a number of bacterial isolates.


The incidence of infection in our centre is low and the pattern of microbes causing surgical site infection at the centre has remained the same over time.


Surgical site infection (SSI) is an infection that develops within 30 days after an operation or within one year if an implant was placed, and the infection appears to be related to the surgery (14). It remains a major cause of morbidity and death among the operated patients(1). Post-operative SSIs are the most common healthcare-associated infection in surgical patients, occurring in up to 5 percent of surgical patients(2,14). In the United States, between 500,000 and 750,000 SSIs occur annually(3,16). Patients who develop a SSI require significantly more medical care. If an SSI occurs, a patient is 60 percent more likely to spend time in the ICU after surgery than is an uninfected surgical patient, and the development of a SSI increases the hospital length of stay by a median of two weeks (12,17). The risk of SSIs continues after discharge. SSIs develop in almost 2 percent of patients after discharge from the hospital and these patients are two to five times as likely to be readmitted to the hospital (12,16,17). The high morbidity associated with SSIs prolongs the hospital stay. This not only increases the medical care cost but also the mortality(10).


Clinical presentation of SSI varies from a spontaneous wound discharge within 7-10 days of an operation to a life-threatening postoperative complication. Most surgical site infections are caused by incision contamination by microorganisms from the patient’s own body during surgery. Infection caused by micro-organisms from an outside source following surgery is less common. Most of surgical site infections are preventable. Surgical site infections are the most common post operative complication, which can adversely affect the life of the patient. The morbidity associated with this not only increases the cost of care but also carries a significant mortality(6, 7). In the United States of America (USA) approximately one million patients develop SSI each year; increasing duration and cost of hospital stay (8).


The magnitude of SSI varies considerably in different parts of the world. The rate of surgical of site infection in USA has been reported to be 2.6 percent, while a report from Tanzania shows this figure to be 19.4 percent (5,7). Surveillance of SSI and providing feedback to the surgical team has been shown to reduce the incidence of surgical site infection and the cost incurred due to it (4). SSIs are classified as being either incisional or organ/space. Incisional SSIs are divided into those involving only skin and subcutaneous tissue (superficial incisional SSI), and those involving deeper soft tissues of the incision (deep incisional SSI)(11).


Patients and methods

Patient characteristics, wound properties and culture data were collected from patients’ files and culture reports. Diagnosis of SSI was made according to the National nosocomial infection surveillance (NNIS. Surgical wounds were classified according to the Centre for Disease Control (CDC) classification (11). Patients’ wounds were inspected from day one post operative until the day of discharge from the hospital and later were followed up for four weeks at the outpatient clinic. Some surgeons open surgical wounds from day three post operative. However, in this study, it was made the standard to open surgical wound from day one post operatively in order to identifye tify thosese with early signs of SSIs.. They were told not to change the wound dressings in tthe peripheral health facilities until they were seen at tthe surgical clinic. Those patients who did not show for the follow up visits were excluded from the study. The data of up visits were excluded from the study. The data of each each patient were filled into a data sheet. For patients patient were filled into a data sheet. For patients who who showed signs of SSIs, wound swabs were done, showed signs of SSIs, wound swabs were taken, put in put in Stuart’s transport medium and sent to the Stuart’s transport medium and sent to the laboratory laboratory for culture and antibiotic sensitivity. The for culture and antibiotic sensitivity. The duration of duration of culture was three days. Microscopy was culture was three days. Microscopy was conducted done for positive cultures. The hospital laboratory had for positive cultures. The hospital laboratory had no no techniques for culturing anaerobic and fastidious techniquesorganisms. Datafor culturinganalysis wasanaerobicconductedandusingfastidiousSPSS organismsver16.0.Statistic.Dataanalysissignificancewasconductedwastestedusing SPSSChi-versquare16.test0.StatisticalandtheP- significancevaluewassetwasat<0tested.05. using

Chisquare test and the P- value was set at <0.05.


ResultsAtotalof263 patients were enrolled in the study but 27 patients who are equivalent to 10.3% of the total Apatientstotalof enrolled263patientswerewerelost enrolledonfollowin upthevisitsstudyandbut 27werepatientsremovedwhofromare theequivalentstudy.Ofto the10.3%remainingofthe total236


patients, enrolled134(56.8%)werewerelost malesonfollowand up102visits(43.2%)and were females. 153 patients were elective patients were removed from the study. Of the remaining 236 whereas 83 were emergencies.

patients, 134(56.8%) were males and 102 (43.2%) The majority of the operations performed were were females. 153 patients were elective patients laparotomy (96 cases), thyroidectomy (35 cases), whereas 83 were emergencies.

head surgery (28 cases) and others constituted the The majority of the operations performed were minority. (Table 1)


laparotomy (96 cases), thyroidectomy (35 cases) and head surgery (28 cases)(Table 1).

Click to view table 1


Of the enrolled patients the majority had(60.2%)clean had wounds clean wounds while only a minority had dirty wounds(Table2)

Click to view table 2


Out of 236 patients, 18 patients developed signs of SSIs, giving an incidence of 7.6%. Wound swabs for culture and sensitivity were taken. 4 patients out of 18 patients had negative cultures, the remainders were culture positive. The majority of SSI were superficial SSIs (61.1%) followed by deep (27.8%) and organ/space (11.1%) SSIs. The rate of infection in elective surgeries was 5.9% and in emergency surgeries was 10.8 % (Table 3).



The majority of the patients who showed signs of SSIs were under the age of 13 years.

Click to view table 3


The majority of infections were seen in laparotomy procedures (Table 4).


Click to view table 4


The overall SSI rate was 7.6%. The infection rates for different classes of wounds were clean wound, 3.5%, clean contaminated wounds, 8.7%, contaminated wounds, 25.4% and dirty wounds, 29.4%. The difference observed in the infection rates in different classes of wounds was statistically significant, pvalue of 0.000 on Chi square test (