Chapter 10

Core Messages

■Periorbital cellulitis can be a serious infection and must be promptly recognized and treated.

■Due to vaccines and antibiotic use in the twentieth century, the microbiologic spectrum of bacteria causing infections in the periorbital area in the twenty-first century is di erent from 10–15 years ago.

■Methicillin-resistantStaphylococcalaureus(MRSA) infections are now a common entity and are aggressive.

■Clinical examination and computed tomographic (CT) scans are the two important aspects of properly evaluating patients with infections.

■A combination of medical antibiotic therapy and surgical intervention is often needed to appropriately treat these infections, especially in teenagers and adults.

10.1Introduction

Infection in the periorbital area is an acute problem that must be astutely recognized and treated. Even though these infections have been around for centuries, the spectrum of bacteria involved continues to evolve with the ever-changing landscape of antibiotics and vaccines. These bacterial infections can be superficial in the preseptal tissue, involve the orbital space, or encompass both. They are a common cause for ophthalmic emergency visits and need to be treated promptly. When the orbit is infected, severe sequelae can result, including death, and thus must be managed aggressively. The goal of this chapter is to review the mechanisms and organisms responsible for cellulitis given that the spectrum of bacteria causing cellulitis is constantly in flux. Current treatment regimens based on current bacteria and antibiotic sensitivity are addressed along with the increasing incidence of MRSA and other antibiotic resistance.

10.2The Infection: Stages, Symptoms, and E ects

Most cellulitis involves the preseptal eyelid tissue. Orbital cellulitis represents an acute infection with inflammation

of orbital contents, often including the preand postseptal eyelids [2, 6, 20, 44]. Periorbital cellulitis can be classified into five stages. The first stage is preseptal cellulitis, in which inflammatory edema remains anterior to the orbital septum. The second stage is posterior spread of this inflammation, behind the arcus marginalis, to a true orbital cellulitis (inflammation of the orbital contents without abscess formation).Third,subperiosteal abscesses may form, in which pus collects between the orbit and the periosteum of the involved sinus. The fourth stage is an orbital abscess, and the fifth involves cavernous sinus thrombosis [6, 24]. The course of treatment varies based on several factors, including the stage of the infection, the source of the infection, the health of the patient, and the underlying organism involved.

By and large, symptomatology and presentation of cellulitis vary with stage of disease. Therefore, a patient with a swollen eyelid can present a challenge but may be readily diagnosed by careful clinical history, examination, and potentially necessary imaging modalities. Stage 1 disease, or preseptal cellulitis, typically presents as tender erythema of the upper or lower eyelids, with no orbital involvement (Fig. 10.1). Since this inflammation is not restricted by the arcus marginalis, it may spread around the eye to involve both the upper and lower lids as well as the cheek and forehead. The history often includes a

Fig. 10.1 Patient with 2 days of progressive swelling and discomfort in the right upper eyelid. Note the eye is white and quiet, and there is normal motility

concurrent sty, recent trauma, or sometimes nothing that the patient can recall. Examination often demonstrates lid pathology with a focal hordeolum or innocuous injury and surrounding edema and erythema that is often tender and warm to the touch. Proptosis, restricted motility, diplopia, vision changes, pupillary defects, or other optic nerve complications will be absent.

Orbital cellulitis, however, represents a more severe ophthalmic condition with significant morbidity, including the possibility of blindness from optic nerve compression or invasion and even mortality (Fig. 10.2a, b) [10, 13, 43, 48, 49]. When infection and inflammation extend posterior across the orbital septum, edema of the orbit and associated increased orbital pressure provide for

Summary for the Clinician

■Orbital cellulitis represents an acute infection with inflammation of orbital contents, often including the preand postseptal eyelids

■Periorbital cellulitis can be classified into five stages.

■The first stage is preseptal cellulitis, in which inflammatory edema remains anterior to the orbital septum.

■The second stage is posterior spread of this inflammation, behind the arcus marginalis.

■In the third stage, subperiosteal abscesses may form as pus collects between the orbit and the periosteum of the involved sinus.

■The fourth stage is an orbital abscess.

■The fifth involves cavernous sinus thrombosis.

It is good that most patients present with an early stage that will advance, if untreated, to later stages. However, there is no exact correlation between extent of cellulitis and clinical presentation. Further, patients do not necessarily progress stage by stage. Last, lab work is historically ine ective in establishing or aiding a diagnosis [26, 35, 37]. Cultures are positive only 50% of the time, blood cultures are typically negative without underlying bacteremia, and white blood cell counts and c-reactive protein levels are usually unreliable [23, 35]. That stated, any abscess or conjunctival discharge that can potentially be cultured should be.

10.3Etiology

Preseptal cellulitis in the periorbital area most commonly arises from superficial skin bacteria invading into the preseptal tissue. Superficial wounds to the periorbital area can result in superficial cellulitis. Commonly, inciting factors include periocular trauma, periocular surgery, insect bites, abscesses, stys, impetigo, spread from associated upper respiratory illness, conjunctivitis, blepharitis, or even tooth abscesses [7, 24]. Some of these wounds will result in focal abscess formation, while others result in a more di use cellulitis. Focal abscess can often be treated with simple drainage, especially hordeolums. Once the infection starts to spread along the skin and orbicularis, antibiotic therapy is required.

Preseptal cellulitis can be caused by dacryocystitis as well. The location of the lacrimal sac anterior to the orbital septum is largely responsible for its tendency toward preseptal cellulitis, as opposed to orbital infection. Further, the lacrimal sac inserts on the posterior lacrimal crest and is bu ered posteriorly by the lacrimal fascia, posterior limb of the medial canthal ligament, and deep heads of the pretarsal and preseptal orbicularis muscles. All of these factors preclude posterior extension of lacrimal sac infection [30].

Sinusitis remains the most common cause of orbital cellulitis [6, 20, 24, 35]. Of orbital infections, 60–80% arise secondary to sinus infections, whereas local periocular trauma, periocular surgery, and orbital/ocular surgery are much less-common etiologies given the anatomic barriers mentioned. Most reports show that ethmoid involvement is the most common sinus of origin, followed by maxillary sinusitis [7, 23, 24, 35]. Antecedent upper respiratory infections are common in these scenarios, and contagions typically spread from the ethmoid sinuses across the lamina papyracea or orbital plate of the ethmoid bone [24]. When originating in the maxillary or

10.4Microbiology 151

frontal sinuses, pathogens may spread through the thin bony roof or floor, respectively. These progressions are supported by orbital and frontal venous drainage systems, joined by valveless communications.

Summary for the Clinician

■Preseptal cellulitis in the periorbital area most commonly arises from superficial skin bacteria invading into the preseptal tissue.

■Preseptal cellulitis can be caused by dacryocystitis as well.

■Sinusitis remains the most common cause of orbital cellulitis.

10.4Microbiology

Certainly, microbial pathogenesis of periorbital infection is dictated by cause as an isolate from a maxillary sinus infection may be di erent from invasion of the periorbita from superficial local trauma. Further, isolation is di - cult as wound cultures are positive in only half of patients [35, 37]. In the late twentieth century, based on positive cultures, Haemophilus influenza (H. flu) had been the most common pathogen responsible for orbital cellulitis prior to the advent of its vaccine [37]. Also, H. flu would commonly progress to subsequent sepsis and central nervous system infection in pediatric cases. Epidemiologic data support this organism’s consistent decline since the beginning of HiB (Haemophilus influenza type B) vaccination in the late 1980s.

Currently, the most common bacterial isolates in orbital cellulitis include the Staphylococcus species. Coagulase-negative Staphylococcus and Staphylococcus aureus (S. aureus) are common causes of both preseptal cellulitis and postseptal infection. Pseudomonas species,

Streptococcus species, Moraxella catarrhalis, and Ekinella corrodens are all less-common causes of orbital cellulitis, and anaerobic organisms are frequently isolated from adult patients with inflamed sinuses and are generally associated with chronic sinusitis [12, 24, 35, 37].

InourrecentstudyatWillsEyeInstituteinPhiladelphia, we analyzed 33 consecutive cases of orbital cellulitis between 2005 and 2007 and found similar results. Coagulase-negative Staphylococcus was responsible for 23% of the infections, while Streptococcus species were responsible for 16%. Methicillin-sensitive and methicillinresistant S. aureus (MSSA and MRSA, respectively) each accounted for 13%. Haemophilus influenzae, fungi, and