ANTIBIOTICS SUSCEPTIBILITY PATTERN OF DIFFERENT BACTERIA

ABSTRACT

This work investigated the antibiotic susceptibility profile of bacterial associated with wound sepsis of patients attending University of Ilorin, Ilorin, Teaching Hospital. Wound swabs were collected from a total number of Hundred patients with different kinds of wound (surgical wound, burn, ulcers and pressure sores) and cultured, of which 72 samples showed bacterial growth. Six different species of bacteria were isolated. Staphylocococcus aureus (47.2%) Pseudomonas aeruginosa (19.5%), Klebsiella pneumonia (6.85%), Escherichia coli (15.3%), Staphylococcus epidemidis (5.6%) and Streptococcus pyogenes (5.6%). The antibiotics susceptibility test of these bacterial isolate was performed using the Kirby- bauer dist diffusion method. Gantamycin and Sreptomycin shows high effectiveness to all the isolate except Staphylococcus epidermis and Klebsiella with pefloxacin and ceftadine respectively showing sensitivity to them. Resistance were shown amongst Ampicillin, contrimoxazole and Tetracycline. This study has revealed Gentamycin as the only antibiotic to which most bacterial isolate from infected wounds were sensitive to. Ampicillin and penicillin were effective against Streptococcus pygenes while zinacef and ceftazidime shows high effectiveness against Klebsiella pneumonia.

KEYWORDS: wound infection: antibiotics susceptibility profile: staphylococcus aureus: gentamycin.

CHAPTER ONE

1. Introduction

             A wound results following disruption of the skin which can be intentional or accidental (Giacometti, 2000).Wound infections cause a burden of disease and morbidity for both the patient and the health services. To the patient it causes pain, discomfort, inconvenience, disability, financial drain, and even death due to complications such as septicemia. It causes financial strain on the health services due to the required high cost of hospitalization and management of the patients.

             A number of factors contribute to wound infection; however microorganisms are the major cause with bacteria being the most prevalent (Obuku, 2012). Early recognition of wound infection and appropriate management is important. Antibiotic therapy and surgical management are the cornerstone measures whereby antibiotics offer adjuvant treatment. Wound infection can be caused by single bacteria or multiple microorganisms. Surgical site infections are the second most common cause of nosocomial infections after urinary tract infections (Perencevich,2003)              Most surgical site infections occur in ambulatory patients after discharge from the hospital and

therefore beyond the hospital infection control surveillance programs (Cosgrove, 2003). Prolonged preoperative hospital stay and exposure to diagnostic procedures has been associated with increased rate of surgical site infection. In clean surgical procedures, Staphylococcus aureus is the most common pathogen while Pseudomonas aeruginosa is the most common gram negative bacilli.

            A number of studies indicate an increase in antibiotic resistant microorganisms in surgical patients. Resistant bacteria causes severe infections that are expensive to diagnose and difficult to treat. The mechanism by which resistance develops is complex and can result in multi-drug resistant bacterial strains due to simultaneous development of resistance to several antibiotics. Determination of local bacterial sensitivity patterns to antibiotics is important in providing a guide for antibiotic selection.

            There are factors that increase the risk of wound infection which include patient characteristics such as; age, obesity, malnutrition, endocrine and metabolic disorders, smoking, hypoxia, anaemia, malignancies and immunosuppressants (WHO, 2007). Other factors are the state of the wound which includes nonviable tissue in the wound, foreign bodies, tissue ischaemia, and formation of haematomas, long surgical procedures, and contamination during operation, poor surgical techniques, hypothermia and prolonged pre-operative stay at the hospital.

             Wound infections can be prevented by restoring blood circulation as soon as possible relieving pain, maintaining normal body temperature, avoiding tourniquets, performing surgical toilet and debridement of the wound as soon as possible, administration of antibiotic prophylaxis for deep wound and high risk infections (WHO, 2007). High risk wounds include contaminated wounds, penetrating wounds, abdominal trauma, compound fractures, wounds with devitalized tissue; high risk anatomical sites such as hands and feet. Antibiotic prophylaxis should be started two hours before the surgical procedures.

            Establishment of the causative microorganism is important and treatment should be initiated based on the bacterial sensitivity patterns. Topical silver dressings have been used to treat infected wounds however; there is no evidence for their efficacy due to multiple microbial aetiologies. (Vermenlen, 2007). To achieve optimum antimicrobial therapy, the biofilm load should be reduced to enhance drug concentration at the wound site (Strup et al, 2013).

             Bacterial wound infections are a common finding in open injuries. Severe and poorly managed infections can lead to gas gangrene and tetanus which may cause long-term disabilities (Bjarnsholt, 2013). Chronic infection can cause septicemia or bone infection which can lead to death. Sepsis associated encephalopathy increases morbidity and mortality especially in the ICU patients (Maramattom, 2007).

             Infection is an important cause of morbidity and mortality in hospitalized burn patients in patients with burn over more than 40% of the total body surface area, 75% of all deaths following thermal injuries are related to infections (Vindence,2005). The rate of nosocomial infections is higher in burn patients (WHO, 2007)due to  various  factors like nature of burn injury itself, immunocompromised  status of the patient (Preuitt,2008), age of the patient, extent of injury, and depth of burn  in combination  with microbial factors such  as type and  number of organisms, enzyme and  toxin  production, colonization  of the burn wound site, systemic dissemination of the colonizing organisms(Preuitt,2004). Moreover the larger area of tissue is exposed for a longer time that renders patients prone to invasive bacterial sepsis. In extensive burns when the organisms proliferate in the eschar, and when the density exceeds 100,000 organisms per gram of tissues, they spread to the blood and cause a lethal bacterenia. Therapy of burn wound infections is therefore aimed at keeping the organisms’ burden below 100,000 per gram of tissues which increases the chances of successful skin grafting.

            The denatured protein of the burn eschar provides nutrition for the organisms. A vascularity of the burned tissue places  the  organisms  beyond  the  reach  of  host  defense  mechanisms  and  systemically  administered  antibiotics  (Canton,2002).  In addition, cross-infection results between different burn patients due to overcrowding in burn wards.  Also  thermal destruction  of  the  skin  barrier  and  concomitant  depression  of  local  and  systemic  host  cellular  and humeral  immune responses  are  pivotal  factors  contributing  to  infectious  complication  in  patients  with  severe  burn  (Maramattom,2007).  Burn wound infections are largely hospital acquired and the infecting pathogens differ from one hospital to another. The burn wound represents a susceptible site for opportunistic colonization by organisms of endogenous and exogenous origin; thermal injury destroys the skin barrier that normally prevents invasion by microorganisms. This makes the burn wound the most frequent origin of sepsis in these patients (Anguzu, 2005). Burn wound surfaces are sterile immediately following thermal injury, these wounds eventually become colonized with microorganisms, gram-positive bacteria that survive the thermal insult, such as S. aureus located deep within sweat glands and hair follicles, heavily colonize the burn wound surface within first 48h (Oduyebo, 2008).                    Topical  antimicrobials  decrease  microbial  overgrowth  but  seldom  prevent  further  colonization  with  other potentially  invasive bacteria and  fungi. Gastrointestinal  and  upper  respiratory  tract  and  the  hospital environment ( Hansbrough,2007). A susceptible site for opportunistic colonization by organisms of endogenous and exogenous origin; Following colonization,  these organisms start penetrating  the  viable  tissue depending  on  their  invasive capacity, local wound  factors and  the degree of the  patient  s  immunosuppression. If sub-eschar  tissue is  invaded,  disseminated infection  is  likely  to  occur,  and  the  causative  infective  microorganisms  in  any  burn  facility  change  with  time Individual organisms are brought into the burns ward on  the wounds of new patients. These organisms then persist in the resident  flora  of  the  burn  treatment  facility  for  a  variable  period  of  time,  only  to  be  replaced  by  newly  arriving microorganisms. Introduction of new topical agents and systemic antibiotics influence the flora of the wound (NCCLS, 2000). The aim of the present study was to obtain information about the type of isolates, identification and antimicrobial sensitivity of bacterial wound infections in burn patients.

             Most wound infections can be classified into two major categories; skin and soft tissue infections although they often overlap as a consequence of disease progression. Infections of hospital acquired wounds are among  the  leading nosocomial causes of morbidity a4nd increasing medical expense .Routine surveillance for hospital acquired wound infection is recommended by both the centers for disease control and prevention and surgical infection  society .

            The most useful classification of wound from a practical point of view is the rank and wakefield classification (Russell et al., 2004) which classified wounds into tidy and untidy wounds. Tidy wounds are inflected by sharp instrument and contain no devitalized tissue. Examples are surgical incisions, cut from glass, knife and machete. Skin wounds will usually be single and clean cut. Untidy wounds results from crushing, tearing, avulsion, vascular injury or burns and contain devitalized tissue skin wounds will often be multiple and irregular.

            Open wounds can be classified into a number of different types according to the object that caused the wound. Types of open wound include: incision or incised wounds, laceration, abrasions (grazes) puncture wounds and gunshot wounds, penetration wounds and gunshot wounds. Closed wounds have fewer categories but are just as dangerous as open wounds. The types of closed wounds include: contusion, hematoma, crushing injuries. Bruise, contusion and Hematoma: a closed blunt injury may result in a bruise or contusion. There is bleeding into the tissue and visible discoloration where the amount of bleeding is sufficient to create localize collection in the tissue, it is described as hematoma.

Puncture wounds and Bites: puncture wound is an open injury in which foreign materials and organisms are likely to be carried deeply into the underlying tissues. A major danger is that they may give rise to an abscess. They are caused by an object puncturing the skin such as nail or needle.