First aid after accidental exposure to infectiuos microorganisms

The following is an excerpt of the contribution of D.H.M. Gröschel, K.G. Dwork, R.P. Wenzel, and L.W. Scheibel, Laboratory accidents with infectious agents, in: B.M. Miller et al., Laboratory Safety: Principles and Practices. American Society for Microbiology, Washington, D.C., 1986.

Accidental exposure to infectious microorganisms is an expected, although rare, event in hospital, research, and industrial laboratories. ... In this chapter, first aid to laboratory employees after accidental exposure to microorganisms is discussed.

After known exposure, no emergency procedures can be wholly relied upon to prevent infection. Indeed, the availability of emergency measures should never permit the worker an illusion of complete protection lest he be lured into lowering the necessary standards of safety.

The person in charge of first aid assistance should be familiar with the potentially hazardous microorganisms used in the laboratory ...... First aid after exposure consists of three steps:

(i) removal or dilution of infectious material and institution of first aid measures;

(ii) assessment of the infection risk;

(iii) referral to a physician for treatment and evaluation for prophylaxis.

Infectious material can be removed or diluted from the intact or broken skin and mucosa by washing with copious amounts of water and soap. Antiseptics such as alcohol, tincture of iodine, idophor or chlorohexidine preparations should be applied. Contamination of the eyes requires immediate flushing with water or ophthalmic saline irrigation solution. Puncture or bite wounds should be left bleeding freely. Sucking of wounds may assist in removing inoculated materials and stimulate bleeding, but too vigorous manipulation of closed deep wounds may assist in the hematogenous and lymphatic spread of pathogens.... .

If oral contamination has occurred, the mouth should be rinsed immediately with tap water. lf dangerous microbiologic material is swallowed, several glasses of water should be drunk and then vomiting should be induced by stimulating the back of the throat with the tip of a finger. ....

The assessment of the infection risk should include an evaluation of the type and amount of infectious material, the mode of transmission, the portal of entry, and the general and specific conditions of the host. For some infectious diseases the infectious dose has been established by voluntary or accidental inoculation. ......

.... In research and industrial laboratories employees are often immunized against the microorganisms with which they are working. This information should be known to the person administering first aid. The employee's health status needs to be assessed, because immunosuppressive or other chronic diseases or pregnancy may influence the steps to be taken for definitive treatment of the accident victim.

Whether or not prophylactic measures are indicated needs to be decided by a physician or his delegate. Many laboratories have established guidelines or procedural policies regarding occupational exposure to infectious materials. The recommended prophylaxis or therapy is sometimes administered in the first aid station or the employee health service (1). The laboratory director should advise the contract services of a clinic or hospital or the employee's personal physician about the spectrum of organisms present in the laboratory and the specific prophylactic or therapeutic measures which are recommended.

Prophylactic measures should be applied only under the direction of a physician and may include local therapy such as instillation of antiseptic or antibiotic eye drops; administration of specific or nonspecific immunoglobulin; vaccination, e.g., for the prophylaxis of tetanus in a previously non-immunized patient; and the use of specific antimicrobial substances. If the laboratory uses a limited number of potentially pathogenic microorganisms, their antimicrobial susceptibility profile should be established and communicated to the employee's medical care facility.

In cases of accidents with microorganisms for which serological tests are available or can be developed, a base-line serum sample should be obtained at the time of occurrence. Preferably, base-line sera from all laboratory personnel should have been collected and stored, and a second serum sample is obtained at the time of exposure or onset of symptoms.

All accidents should be reported to the laboratory safety officer and the laboratory director. A report should be filed and maintained for medical and epidemiological purposes. .........

.... Routes of laboratory-acquired infections include the following:

(i) Intact mucosa. Infectious droplets may reach the mucosal surfaces of the eye. nose, or oral cavity. Organisms may be transmitted to the mucosa through devices such as pipettes, by spraying from syringes, by droplets and aerosols generated by laboratory procedures such as high-speed blending and centrifugation or centrifuge accidents, and by direct contact (finger) from the source or from contaminated fomites.

(ii) Broken skin. Infectious material may enter directly or via fomites through abrasions, small cuts, or larger accidental wounds or through inoculation with needles or other sharp items. Insect vectors may transmit disease through stings, bites, or contamination of a bite wound. Certain microorganisms may enter the body through the unbroken skin, e.g., spirochetes and schistosomes, or infect the skin tissue directly, such as dermatophytes.

(iii) Animal contact. Animal contact includes animal bites or scratches, transmission by vectors such as ticks or fleas, contamination of hands, and exposure to contaminated aerosols, dusts, body fluids, and excreta.

(iv) Inhalation. Entry into the body is achieved through droplets and aerosols such as those generated by sprays from syringes, centrifugation, and tissue mincing, or with dust (animal bedding).

(v) Ingestion. Microorganisms reach the gastrointestinal tract directly from an infected source (faecal-oral transmission) or through a contaminated carrier.

Careless storage of food in a laboratory or eating and drinking at the laboratory bench are other causes of transmission.

In all cases of accidental exposure to infectious agents, the exposed employee should be referred to a physician for evaluation and appropriate treatment or prophylaxis.

Guidelines prepared for CABRI by BCCM/LMBP in cooperation with DSMZ and NCCB, 7 May 1998
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Copyright CABRI, 1998