A surgical site infection (SSI) develop when

bacteria Bacteria (; : bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of Prokaryote, prokaryotic microorganisms. Typically a few micr ...

infiltrate the body through

surgical incision A surgical incision is a cut made through the skin and soft tissue to facilitate an operation or procedure. Often, multiple incisions are possible for an operation. In general, a surgical incision is made as small and unobtrusive as possible ...

s. These bacteria may come from the patient's own

skin Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation. Other animal coverings, such as the arthropod exoskeleton, have different ...

, the

surgical instrument A surgical instrument is a medical device for performing specific actions or carrying out desired effects during a surgery or operation, such as modifying biological tissue, or to provide access for viewing it. Over time, many different kinds of ...

s, or the environment in which the procedure is performed. An infection is designated as an SSI if it develops at the site of a

surgical wound A surgical incision is a cut made through the skin and soft tissue to facilitate an operation or procedure. Often, multiple incisions are possible for an operation. In general, a surgical incision is made as small and unobtrusive as possible t ...

, either because of

contamination Contamination is the presence of a constituent, impurity, or some other undesirable element that renders something unsuitable, unfit or harmful for the physical body, natural environment, workplace, etc. Types of contamination Within the scien ...

during surgery or as a result of postoperative complications. For the infection to be classified as an SSI, it should occur within 30 days after surgery or within 1 year if an

implant Implant can refer to: Medicine *Implant (medicine), or specifically: **Brain implant **Breast implant **Buttock augmentation, Buttock implant **Cochlear implant **Contraceptive implant **Dental implant **Fetal tissue implant **Implantable cardiov ...

is involved. Surgical site infections that are limited to the skin and

subcutaneous tissue The subcutaneous tissue (), also called the hypodermis, hypoderm (), subcutis, or superficial fascia, is the lowermost layer of the integumentary system in vertebrates. The types of cells found in the layer are fibroblasts, adipose cells, and ma ...

s are classified as superficial incisional SSIs. These

infection An infection is the invasion of tissue (biology), tissues by pathogens, their multiplication, and the reaction of host (biology), host tissues to the infectious agent and the toxins they produce. An infectious disease, also known as a transmis ...

s are the most common type, accounting for more than 50% of all reported surgical site infections.

Symptoms

The symptoms of a surgical site infection (SSI) can vary depending on the severity and type of infection. Common signs include redness and

pain Pain is a distressing feeling often caused by intense or damaging Stimulus (physiology), stimuli. The International Association for the Study of Pain defines pain as "an unpleasant sense, sensory and emotional experience associated with, or res ...

around the area of the surgical wound. A cloudy or

purulent fluid Pus is an exudate, typically white-yellow, yellow, or yellow-brown, formed at the site of inflammation during infections, regardless of cause. An accumulation of pus in an enclosed tissue space is known as an abscess, whereas a visible collecti ...

may drain from the wound, indicating infection.

Fever Fever or pyrexia in humans is a symptom of an anti-infection defense mechanism that appears with Human body temperature, body temperature exceeding the normal range caused by an increase in the body's temperature Human body temperature#Fever, s ...

is another common symptom, which may accompany other signs such as increased warmth, swelling, or delayed healing at the surgical site. Additional symptoms may also occur, depending on the nature and extent of the infection.

Types

SSIs occur in different areas such as skin, tissue,

organ Organ and organs may refer to: Biology * Organ (biology), a group of tissues organized to serve a common function * Organ system, a collection of organs that function together to carry out specific functions within the body. Musical instruments ...

s, "implanted material, like a

hip replacement Hip replacement is a surgery, surgical procedure in which the hip joint is replaced by a prosthetic implant (medicine), implant, that is, a hip prosthesis. Hip replacement surgery can be performed as a total replacement or a hemi/semi(half) repl ...

". The

Centers for Disease Control and Prevention The Centers for Disease Control and Prevention (CDC) is the National public health institutes, national public health agency of the United States. It is a Federal agencies of the United States, United States federal agency under the United S ...

(CDC) classifies SSIs into three categories: superficial incisional, deep incisional, and organ/space infections. *Superficial incisional infection: involve only the outer layer of skin where the incision was made. *Deep incisional infection: affect deeper tissues beneath the incision, such as

muscle Muscle is a soft tissue, one of the four basic types of animal tissue. There are three types of muscle tissue in vertebrates: skeletal muscle, cardiac muscle, and smooth muscle. Muscle tissue gives skeletal muscles the ability to muscle contra ...

s and the surrounding

connective tissue Connective tissue is one of the four primary types of animal tissue, a group of cells that are similar in structure, along with epithelial tissue, muscle tissue, and nervous tissue. It develops mostly from the mesenchyme, derived from the mesod ...

s. *Organ or space infection: occur in internal areas of the body, such as an organ or a cavity between organs, that were involved in the surgical procedure.

Pathogen involving

The microorganisms responsible for surgical site infections (SSIs) are often derived from endogenous

flora Flora (: floras or florae) is all the plant life present in a particular region or time, generally the naturally occurring (indigenous (ecology), indigenous) native plant, native plants. The corresponding term for animals is ''fauna'', and for f ...

. The specific pathogens involved typically vary depending on the type of surgical procedure performed. Among the most frequently identified organisms are ''

staphylococcus aureus ''Staphylococcus aureus'' is a Gram-positive spherically shaped bacterium, a member of the Bacillota, and is a usual member of the microbiota of the body, frequently found in the upper respiratory tract and on the skin. It is often posi ...

'', coagulase-negative ''

staphylococci ''Staphylococcus'', from Ancient Greek σταφυλή (''staphulḗ''), meaning "bunch of grapes", and (''kókkos''), meaning "kernel" or " Kermes", is a genus of Gram-positive bacteria in the family Staphylococcaceae from the order Bacillale ...

'', ''

enterococcus faecalis ''Enterococcus faecalis'' – formerly classified as part of the group D '' Streptococcus,'' is a Gram-positive, commensal bacterium naturally inhabiting the gastrointestinal tracts of humans. Like other species in the genus '' Enterococcus'', ' ...

'', and ''

escherichia coli ''Escherichia coli'' ( )Wells, J. C. (2000) Longman Pronunciation Dictionary. Harlow ngland Pearson Education Ltd. is a gram-negative, facultative anaerobic, rod-shaped, coliform bacterium of the genus '' Escherichia'' that is commonly fo ...

''. These

pathogen In biology, a pathogen (, "suffering", "passion" and , "producer of"), in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a Germ theory of d ...

s reflect the microbiological environment of the surgical field and the body sites exposed during the operation.

Mortality

SSIs are a significant cause of complications following

surgery Surgery is a medical specialty that uses manual and instrumental techniques to diagnose or treat pathological conditions (e.g., trauma, disease, injury, malignancy), to alter bodily functions (e.g., malabsorption created by bariatric surgery s ...

, contributing to both perioperative

morbidity A disease is a particular abnormal condition that adversely affects the structure or function of all or part of an organism and is not immediately due to any external injury. Diseases are often known to be medical conditions that are asso ...

and mortality. These infections are responsible for a large number of healthcare-associated infections globally, including over 2 million cases annually in the United States alone.

Studies

There has been ongoing research on the SSIs, with the

National Institute for Health and Care Research The National Institute for Health and Care Research (NIHR) is the British government's major funder of clinical, public health, social care and translational research. With a budget of over £1.2 billion in 2020–21, its mission is to "impr ...

(NIHR) Global Research Health Unit on Global Surgery and GlobalSurg Collaborative. Several keypoints have been identified as Low income countries have a disproportionately greater burden of SSIs (with 4 times the burden in children) than other countries and higher rates of antibiotic resistance. More studies have investigated the role of perioperative high fraction

Oxygen Oxygen is a chemical element; it has chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen group (periodic table), group in the periodic table, a highly reactivity (chemistry), reactive nonmetal (chemistry), non ...

and Telemedicine in preventing and improving outcomes of SSIs. A study conducted by researchers at the

University of Washington School of Medicine The University of Washington School of Medicine is the medical school of the University of Washington, a public research university in Seattle, Washington. According to ''U.S. News & World Report''s 2022 Best Graduate School rankings, University ...

, published in 2024 and featured by the

University of Minnesota The University of Minnesota Twin Cities (historically known as University of Minnesota) is a public university, public Land-grant university, land-grant research university in the Minneapolis–Saint Paul, Twin Cities of Minneapolis and Saint ...

and the

American Association for the Advancement of Science The American Association for the Advancement of Science (AAAS) is a United States–based international nonprofit with the stated mission of promoting cooperation among scientists, defending scientific freedom, encouraging scientific responsib ...

, and ''

Nature Nature is an inherent character or constitution, particularly of the Ecosphere (planetary), ecosphere or the universe as a whole. In this general sense nature refers to the Scientific law, laws, elements and phenomenon, phenomena of the physic ...

'' involved 210 adult patients undergoing spinal fusion surgery and found that most infections following surgery were caused by bacteria already present on the patients' skin. The researchers aimed to understand why surgical site infections (SSIs), which occur in about 1 in 30 surgeries, have not decreased despite infection prevention measures. They analyzed preoperative patient microbiomes and postoperative SSI samples using

genomic Genomics is an interdisciplinary field of molecular biology focusing on the structure, function, evolution, mapping, and editing of genomes. A genome is an organism's complete set of DNA, including all of its genes as well as its hierarchical, ...

analysis. Of the 210 patients, 14 (6.8%) developed SSIs. Skin,

nasal Nasal is an adjective referring to the nose, part of human or animal anatomy. It may also be shorthand for the following uses in combination: * With reference to the human nose: ** Nasal administration, a method of pharmaceutical drug delivery * ...

, and

rectal The rectum (: rectums or recta) is the final straight portion of the large intestine in humans and some other mammals, and the Gastrointestinal tract, gut in others. Before expulsion through the anus or cloaca, the rectum stores the feces te ...

samples were taken before surgery from most patients.

Whole genome sequencing Whole genome sequencing (WGS), also known as full genome sequencing or just genome sequencing, is the process of determining the entirety of the DNA sequence of an organism's genome at a single time. This entails sequencing all of an organism's ...

of 22 SSI samples revealed that 86% were similar to bacterial strains found on the patients' skin before surgery. Further analysis of 59 additional SSIs in the same hospital showed no common bacterial strains, suggesting that the infections were not linked to external hospital sources.

Global Surgical-Site Infection score

A ‘Global Surgical-Site Infection’ score was published by

NIHR The National Institute for Health and Care Research (NIHR) is the British government's major funder of clinical, public health, social care and translational research. With a budget of over £1.2 billion in 2020–21, its mission is to "improv ...

Global Research Health Unit on Global Surgery and GlobalSurg Collaborative that allows the SSIs risk prediction with perioperative variables.

Symptoms

Types

Pathogen involving

Mortality

Studies

Global Surgical-Site Infection score

See also

References

Further reading