European Journal of Cardiovascular Medicine

Post operative wound infections are among the most common complications in patients who undergo surgical procedures. It is also the third most frequently reported nosocomial infection in the hospital population. Wound is defined as a breach in the continuum of normal tissue causing variety of changes at cellular and molecular levels resulting in sequelae. Surgical site infection (SSI) is defined as, an infection occurring within 30 days after a surgical operation, affecting either incision or from deeper tissues at the operation site. The deeper infections may involve organ or body space.

The overall incidence of wound sepsis in India varies from 10-33%. Similar studies made in different areas show vide variation i.e. 2.8% to 26.6% in the Obstetric population. Various reasons like anaemia, diabetes mellitus, multigravida, hypertension, obesity all were attributed as causative factors for the increased reports of SSI. Apart from these, emergence of resistant strains of pathogenic bacteria, has become a major concern. Similarly even in government health care institutions overload of patients, limitation of manpower, budgetary constraints and not following infection control measures all contribute to increase in SSI.[1,2]

In a developing country like India more than 80% population belong to middle and lower socio economic background are from rural areas. Despite improved health care facilities most women of child bearing age group still adhere to primitive traditional practices in dealing with personal hygiene, maternity and Gynaecological problems. These are the main group, seeking health care in government hospitals being more vulnerable to SSI.

Advances in operative conditions like good ventilation, sterilization methods, surgical technique, antimicrobial prophylaxis, understanding of wound infection has made little impact in reducing the number of SSI. This resulted in increased morbidity, mortality, prolonged hospital stay and also causing increased economic burden to the patient as well as to the government. As such, I undertook the present study with an Intention, to know the spectrum of aerobic bacteria causing post operative wound infections in Obstetrics & Gynaecology Department at Government General Hospital, Kakinada and to study the antibiogram of the isolates.

The present study was undertaken to know the bacteriological profile of surgical site infections in Obstetrics and Gynaecology ward, including their antibiogram and find the preventive measures. This work was done in collaboration with Department of Obstetrics and Gynaecology, Government general hospital, Kakinada during the period December 2014 to December 2016. Clearance certificate was obtained from ethical committee in the institution. The sample size includes 100 samples of pus were collected from all cases of SSI in common post operative ward mostly in the form of swabs & few as aspirates.

Inclusion criteria:

Age group 20-60 years, Presence of post operative SSI’s, involves only the skin or subcutaneous tissue.

Exclusion criteria:

Infection of Episiotomy wound, infection occurring 30 days after operation

Inoculum for antibiotic susceptibility testing was prepared by emulsifying 4 – 5 similar looking colonies in a test tube containing 1 – 2 ml nutrient broth and incubated for 2-3hours. The turbidity after incubation was matched to 0.5 McFarland standard [Contains 108 CFU/ml]. After the standardization of the inoculum, a freshly prepared, dried Mueller-Hinton-Agar [MHA] plate was inoculated by pouring the inoculum onto the plate. The inoculum was spread evenly and the excess was poured off the plate. The panel of antibiotic discs were placed on the plate and was incubated aerobically at 35oC ± 2oC for 24 hours

The plate was examined to confirm that a lawn of good growth has been obtained. Using a dark background and reflected light a ruler was used to measure the zone of inhibition around each disc. Once the zone sizes were recorded, they were interpreted as sensitive or resistant as per CLSI guidelines. 100 samples of pus were collected for Microbiological processing from all cases of SSI in common post operative ward mostly in the form of swabs & few as aspirates. The results were analyzed.

A total of 100 samples were processed and culture isolations made were 87 (87%). 87 culture positives samples 80 showed single isolates and 2 isolates were made in 7 samples making a total of 94 isolates in 87 samples. A total of 100 samples were processed and there were 94 bacterial isolations, in which 43(45.7%) were resistant strains.

Table-1: Age wise distribution of the study sample (n=100)

Majority members in the study group were between ages of 20-49 years.

Table-2: Culture isolations in samples of different categories

More no of pus samples are received from Obstetric cases i.e. 70(70%) compared to only 30 (30%) samples are from Gynaec cases. There were 88.6% and 83.3% of culture isolations were made from their specimens. Similarly in a total of 100 samples there were 87% culture positives were isolated as 13% were culture negatives.

Table-3: Different isolates in the culture positives. (n=94)

Bacterial isolations made in the study include 42 (44.70%) belong to Enterobacteriaceae species followed by Non fermenters and Staphylococcus sps 26 (27.65%) each. In 42 Enterobacteriaceae sps isolated 27(64.28%) are Klebsiella pneumoniae followed by 13(30.96%) Escherichia coli and 2 (4.76%) were Proteus mirabilis.

Table-4:Gram positive cocci and Bacterial isolates in culture (n=26)

There were 26 Staphylococcus sps isolated in which 16 were Staphylococcus aureus and 10 belong to CoNS. In total of 10 CoNS isolates, 8 were Staphylococcus epidermidis & 2 were Staphylococcus haemolyticus. A total of 26 Non fermenters were isolated in which 24 were Pseudomonas aeruginosa and 2 belong to Acinetobacter baumanii. A total of 94 bacterial isolates were isolated in the study, 27(28.72%) were Klebsiella pneumoniae.

Table-5: Resistant strains of Staphylococci isolated

In 16 isolations of Staphylococcus aureus 14(87.5%) were MRSA strains. Similarly, in 10 CoNS sps resistant strains isolated were 6 (60%).In total 26 isolations of Staphylococcus species 20 were resistant strains i.e. 76.92%

Table-6: Resistant strains of Enterobacteriaceae isolated in the study

In 40 Enterobacteriaceae sps isolated, K.pneumoniae were 27, out of which 11(40.7%) were ESBL & 3 (11.1%) were Amp C producers. E.coli were 13, out of which 4 (30.7%) were ESBL& 2 (I5.3%) were AmpC producers and there were no ESBL & Amp C producers for P.mirabilis

Table-7: Resistant strain of Pseudomonas aeruginosa isolated in the study

In a total of 24 Pseudomonas isolates, 3 were found to be resistant strains of non fermenters, which includes 2 MBL & 1 ESBL producers.

Table-8: Antibiogram of staphylococcus aureus for primary line of drugs

Total of 2 routine isolates of Staphylococcus aureus, (100%) were sensitive to Clindamicin, Amikacin and Cefoxitin. Similarly in 4 isolates of CoNS were sensitive to Clindamicin, Gentamicin, Cotrimoxizole, Erythromycin & Cefoxitin followed by 2(50%). Amikacin & Ciprofloxacin. In a total 6 isolates of Staphylococcus species the highest sensitivity was observed for Clindamicin and Cefoxitin 6(100%).

Table-9: Antibiogram in the resistant strains of Staphylococcus aureus

In total of 14 isolates of Staphylococcus aureus the highest sensitivity was observed for Linezolid & Teicoplanin i.e14 (100%).

Similarly, out of 6 isolates of CoNS the highest sensitivity for Linezolid & Teicoplanin 6 (100%).

In total of 20 isolates of Staphylococcus species highest sensitivity was observed to Linezolid & Teicoplanin 20 (100%).

Table-10: Antibiogram of Enterobacteriaceae for routine drugs

In 27 isolates of Klebsiella pneumoniae 23(85.1%) were sensitive to Amikacin. Where as in 13 isolates of Escherichia coli good sensitivity was observed for Amikacin in 11 (84.6%). Of the 2 isolates of Proteus mirabilis both are sensitive to Amikacin & Chloramphenicol 2(100%). In total 42 isolates of all sps of Enterobacteriaceae the highest sensitivity was observed for Amikacin 36 (85.7%).

Table-11: Sensitivity pattern in the resistant strains of Enterobacteriaceae for reserve drugs

In 14 isolates of Klebsiella pneumoniae 14 (100%) were sensitive to Colistin & Imipenem, Meropenem 13 (93%).Similarly out of 6 isolates of Escherichia coli 5 (83.3%) were sensitive to Colistin. Out of 20 isolates of Enterobacteriaceae strains show highest sensitive to Colistin i.e. 19(95%).

Table-12: Antibiogram of Non-Fermenters for routine drugs

Pseudomonas isolates were sensitive to Imepenem i.e. 21(87.5%). Similarly in 2 isolates of Acinetobacter sps both i.e. 100% were sensitive to Imepenem,

In total 26 isolates of Non fermenters the highest sensitive was observed for Imipenem 21 (88.46%).

Table-13: Antibiogram of resistant strains of Pseudomonas aeruginosa (n=3)

3 isolates i.e. 3 (100%) were sensitive to Colistin & Polymyxin- B, followed by 2(67%) Netilmicin, Cefoperazone & Sulbactum and to Piperacillin & Tazobactum.

Surgical site infections constitute a global health problem both in economic and human term. Multiplicity of factors influence SSI rate in clinical practice. Most effected age group in the current study belong to reproductive age group between 20-49 years, who are more vulnerable to Obstetrics &Gynaecological problems. In 100 pus samples processed 87 (87%) were culture positives and 13(13%) showed no growth. Similar studies made previously at different institutions shown high as well as low values AbuHena saiful et al[3], Rahman et al[4] Hoque M M et al[5], Devjani et al[6] with 91.3%, 94%, 84%,81% and 87%. The reason could be due to variation in prevalence rate of infections in different areas and also depends on many factors like local conditions, laboratory facilities and personnel and immune status of the subjects.70 compared to only 30 from patients who underwent Gynaecological surgeries. Being a tertiary care hospital most of the patients come to hospital with obstetric complications prone for emergency surgeries compared to elective procedures followed for routine Gynaecological problems.

Further, it’s interesting to note as 96.3% of culture positives were observed in Obstetric emergencies when compared to Obstetric and Gynaecological elective procedures which showed 73.3 and 77% respectively. In other words, wound infections were more frequently seen in emergency surgeries than elective surgeries in Obstetrics. The p value was calculated p<0.5 which is proved to be statistically significant. Similarly in 87 culture positives 80 samples yielded single isolate and more than one organism were isolated in 7 samples. In other words there were total 94 organisms isolated in 87 culture positives.

Table-14: Number of isolates made from each specimen in different studies

The results when compared with other studies showed higher rate of isolation (91.9%) in the present study. There was high no. of multiple isolations in other studies which may be due to the severity of infection and duration of wound. Sometimes the specimen collection technique may be at fault e.g. Like contact with surrounding structures other than wound may yield multiple isolates.

Different types of bacterial isolates in culture positives shows highest 42 (44.70%) were enteric Gram-negative rods followed by 26 (27.65%) each of non-fermenters and Staphylococci sps. Likewise, 45.7% in 94 isolates obtained in the study were proved to be resistant organisms.

In contrast according to recent study in Bulgaria [17] reported aerobic Gram positive including Staphylococcus aureus, Enterococci & CoNS are the commonest organisms causing SSIs in Obstetrics & Gynaecology wards. This could be attributed by differences in geographical locations & behaviour of hospital strains in that area.

Similarly, studies from Western Africa & Asian countries have reported increasing trend of Pseudomonas aeruginosa & other enteric Gram-negative rods as the common organisms causing SSIs. Multiple factors which include environmental contamination, standard of hygiene maintained in hospitals especially in developing countries contribute for reporting high number of Gram-negative pathogens.

The other isolates in the present study were Escherichia coli 13, Proteus mirabilis 2, Acinetobacter baumanii 2 and CoNS were 10. Out of 10 CoNS, 8 were Staphylococcus epidermidis & 2 were Staphylococcus haemolyticus respectively in different groups. 26 Non fermenters were isolated in the present study in which 24 were Pseudomonas aeruginosa when compared to 2 Acinetobacter baumanii.

The predominant isolates seen were Klebsiella pneumoniae 27 followed by Pseudomonas aeruginosa 24 and Staphylococcus aureus 16 in each group. When compared to various studies showed the predominant isolate to be Pseudomonas aeruginosa. In contrast to present study Pseudomonas aeruginosa happens to be the second predominant isolate after Klebsiella pneumoniae.

This can be explained like pseudomonas even Klebsiella is known to survive better in both internal and external environment of the body. Klebsiella sps are equally capable in exhibiting various defense mechanisms to survive thus producing resistant strains. Highest number of resistant strains of Klebsiella sps in a total of 27 isolates.

The antibiograms of organisms in different groups were analysed. There were 26 Gram positive organisms isolated in which Staphylococcus aureus was the predominant isolate numbering 16 and the remaining 10 were CoNS.. All the strains showing resistance to Cefoxitin disc were identified as MRSA & Methicillin resistant CoNS.

Table-15: Sensitivity to different antibiotics of Staphylococcus aureus with other studies

When compared to other studies our results coincides with Ch. Meena et al 2015 for all above tested antibiotics whereas, low level of sensitivity was observed in study of Chaudary et al[16]. The high resistant to penicillin G observed in our study concur with previous studies done in Tanzania & elsewhere in developing countries which also reported high resistance rates of Staphylococcus aureus to penicillin. These findings may be as result of injudicious use of these drugs in the study population leading to high selection pressure of resistant bacteria. All staphylococcal isolates showing zone of <21mm & ≤24mm to cefoxitin 30μg disk are identified as MRSA & Methicillin resistant CoNS respectively. 87.5% of MRSA strains identified in our study coincides to the results of Chaudary et al[16] who have reported 81.4% where as higher number 100% MRSA reported by Anand et al[15].

The high percentage of MRSA isolates in present study indicates most of the strains were from hospital environment. Staphylococci are well known for their survival for longer periods in the places like wards, corridors, inanimate objects, thus causing nosocomial infections. Similarly it is interesting that 60% of CoNS isolated were resistant. The sensitivity pattern of MRSA isolates, Staphylococci showed good sensitivity to Linezolid, Teicoplanin & Vancomycin and low sensitivity to Chloramphenicol.

Table-16: Sensitivity pattern of MRSA strains in different studies

Our study coincides with Shriyan et al[19], Joel Manyahi et al[8], Naomi et al[18], showed 100% sensitivity to Linezolid.

Table-17: Sensitivity to different antibiotics of Enterobacteriaceae in various studies

Comparing the antibiogram of Enteric Gram-negative rods with various studies over years there was drastic reduction in sensitivity to 3rd. generation cephalosporins compared to aminoglycosides which showed little variation in some studies. This can be explained because of overuse of cephalosporins in recent years leading to emergence of resistant strains. Resistance to third generation Cephalosporins might be transferred to the recipient strain along with resistance to Gentamicin or non βlactam antibiotics. ESBL production is encoded by genes that are prevalently located on large conjugative plasmids of 80-160 kb in size. Since these plasmids are easily transmitted among different members of Enterobacteriaceae, accumulation of resistant genes that contain multi resistant plasmids, which exhibit high stability. For this reason, ESBL producing isolates are resistant to a variety of classes of antibiotics. The present study shows Amikacin and Levofloxacin are better alternatives to cephalosporins for the primary line of treatment.

Organisms showing borderline and less sensitive to third generation Cephalosporins when subjected to ESBL and Amp C β lactamase production tests and results. Out of 27 total isolates of Klebsiella pneumoniae, 11 (41%) were ESBL & 3 (11.1%) were Amp C producers. Similarly in total 13 E.coli 4 (31%) were ESBL & 2 (I5.4%) were Amp C producers. There was no ESBL & Amp C for P.mirabilis Regarding ESBL production highest number were seen among Klebsiella pneumoniae 41%, followed by Escherichia coli 31%.

Table-18: βlactamases producing strains of Enterobacteriaceae sps in various studies

The result of our study coincides with Rahman et al regarding Klebsiella pneumoniae and for E. coli with that of Ajay kumar et al[25] Highest ESBL showed by Richa gupta et al[22] for Klebsiella and lowest ESBL showed by Abu Henna MD Saif karim et al[3] for Escherichia. Similarly other studies showed little variation between 24-68%. But the continuous presence of ESBL strains over years is a matter of concern in prescribing drugs.

Similarly earlier studies show less Amp C β lactamase producers compared to later years. This can be explained the introduction of combination drugs to treat ESBL strains and their irrational over usage has triggered for emergence of Amp C β lactamase producing strains. This can be seen in increase reporting in the preceding years of our study. Unlike higher animals’ mutations can occur more frequently in bacteria especially hospital environment due to overuse of antibiotics there is every possibility of increase reporting of this strains in future unless we follow strict antibiotics.

Klebsiella pneumoniae is an important source of transferable antibiotic resistance because ESBL production is encoded by genes that are located on large conjugate plasmids of 80-160 kb size. Large size plasmids most are frequently seen in Klebsiella pnemoniae are highly stable with ESBL resistant genes. In contrast to ESBL, Amp C producing strains are high among Escherichia coli 15.4% in the present study when compare to Klebsiella pneumoniae 11.1%. Antibiotic sensitivity in ESBL producing strains of our study coincides with Naomi et al 2014 & Hoque Asna et al 2013 for all above tested antibiotics.

Table-19: Sensitivity to different antibiotics in ESBL producing isolates of Enterobacteriaceae in various studies

All the above studies including our study shows high sensitivity to Colistin, Imipenem & Meropenem. So these are the drugs of choice for ESBL produced bacterial strains. The antibiogram patterns may vary from time to time & place to place. Various reasons like follow of antibiotic policies in that place or hospital and the standard of hospital in implementation of latest infection control policies etc all matters to explain the difference of results in various studies. Developing countries like India most institutions clinicians have their own choice in selection of antibiotics sometimes over and even unnecessary usage contribute to this variable sensitivity patterns observed. With the emergence of ESBL & Amp C β lactamase production in Escherichia coli, Klebsiella pneumoniae & other Enterobacteriaceae, carbapenems were used as last resort to treat those infections. Studies have reported because of selective pressure even carbapenemases producing Enterobacteriaceae has emerged. The antibiogram of non-fermenters 23 strains show good sensitivity zone to Imepenem followed by Ceftazidime 22, Cefoperazone 20, Amikacin 19, Gentamicin & Levofloxacin were 16, Ciprofloxacin 15 and least number for Piperacillin 8.

Table-20: Sensitivity to different antibiotics of non-fermenters with various studies

As we know piperacillin was sheet anchor for pseudomonas infections in the past but only 30.7% of strains showed sensitivity in our study. Strains showing reduced susceptibility to 3rd. generation cephalosporins and impenem were further tested for ESBL and MBL production.

In the present study Pseudomonas aeruginosa isolates showed 8.3% MBL & 4.2% ESBL producers, our study coincides with Richa gupta et al[22] i.e. 8.3% in MBL production and Serife et al[26]  i.e. 4.2% in ESBL production.

In contrast to Staphylococci, and Enteric Gram negative rods, only 3 resistant strains were isolated in non-fermenters group. All 3 were Pseudomonas isolates which include 2 MBL & 1 ESBL producer. The other non-fermenter reported was 2 Acinetobacter baumanii in which no resistant strains were noticed.

The 3 resistant strains of non-fermenters showed 100% sensitivity to Colistin & Polymyxin. The present study coincides with Behera et al[16] & Richagupta et al[22]. The isolation rate is very small in our study but these are the drugs of choice for ESBL & MBL produced bacterial strains, which need further confirmation in larger sample studies.

Restricted permeability & efflux are common components of the resistance phenotype for β-lactams, aminoglycosides & quinolones and are essentially fundamental properties of the organism. Spontaneous mutations can increase the expression of chromosomal β- lactamase genes. These mutants will be selected under the pressure of antibiotic usage, especially when monotherapy is employed. However, Pseudomonas aeruginosa has always proven to possess an answer to antibiotic therapy, the ominous size of its genome & current lack of knowledge of the function of many genes suggests that this continue to be the cause whatever new therapies are devised. Comparing the antibiograms of various isolates with other studies, we should keep in mind the good sensitivity observed for the above drugs are only temporary. As such their usage should be restricted for extreme emergencies.

A review has reported that hands of health care workers & patients can play a role in transfer of Gram-negative bacteria during cross infection. During the present study, it was noticed there was only one internee who was responsible for dressing more than 15 surgical wounds per session. This is only an example to say similar situations elsewhere raises the risk of cross infection if aseptic procedures are not strictly adhered to.

Most subjects seeking medical aid in this Government set up belong to low socio-economic group and especially during the antenatal period with complications pay less attention to good hygienic practices. Similarly overcrowding of patients in obstetric ward and labour rooms due to increase admissions, limited manpower, not following good barrier methods all contribute to surgical site infections. Many of the bacterial isolates in this present study were resistant strains as such source of SSI is hospital acquired.

Unlike antibiotics the potency of disinfectants used for cleaning and skin preparation are never monitored in Government hospitals. This expresses doubt in their efficacy and is a major contributory factor for SSI. The simple method of good skin preparation with potent disinfectant and wearing a sterile gown before surgery can drastically reduce the rate of SSI. The hospital administration with the help of Microbiologist has to play the key role to organize infrastructure see to strict implementation of antibiotic policies and stringent infection control measures appears to be the only remedy in reducing the SSIs. 

Surgical site infections determine the final outcome of an operation apart from the morbidity and mortality they cause. Though surgical care is very important to prevent wound infection, but some pre and post-operative steps can reduce SSI. All the predominant isolates in the present study and their antibiogram analysis indicate most of SSIs are Hospital acquired many of which are resistant strains. As such formation of infectious control committee has to be made mandatory in all hospitals. The potency of disinfectants used for disinfection of wards and skin preparation, should be monitored regularly and use of good quality disinfectants can drastically reduce SSIs. Drug resistance mechanisms which include ESBL, Amp C betalactamases, MBL producers exhibited by the predominant Gram-negative rods and MRSA strains in Gram positive isolates are due to overuse of antibiotics leading to selective pressure.

Government has to intervene in strict implementation of antibiotic policy in all health care institutions. Availability of drug to patient is restricted only on doctor prescription. Regular appraisal regarding personal hygiene has to be given to all antenatal mothers by HCW and other medical personal. Hospital infrastructure has to be improved by providing more space to accommodate the overload of patients with good ventilation of wards and water facilities. Similarly, sufficient manpower has to be recruited for managing different sections all this to prevent cross infections.

The Microbiologist has very important role in Appraisal to the health authorities regarding antibiogram of different isolates in the institution, enabling them to formulate antibiotic policy. Recommend the disinfectants to be used in wards as well as in pre operative skin preparation by testing their efficacy. Though expensive introduce new sterilization techniques, like Bacillocidrassant and Virkon type chemical disinfection methods can be adopted especially in overcrowded wards in Obstetrics & Gynaecology to bring down SSI.

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