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                                                                   Exhibit 4.5



                            CERTIFICATE OF AMENDMENT

                                       TO

                          CERTIFICATE OF INCORPORATION

                                       OF

                           ACCUMED INTERNATIONAL, INC.


        The undersigned, the President and Secretary of AccuMed International,
Inc., a Delaware corporation (the "Corporation"), do hereby certify as follows:

        1. The Board of Directors of AccuMed International, Inc. duly adopted a
resolution, in accordance with Section 242 of the General Corporation Law of the
State of Delaware, to amend the Certificate of Incorporation of AccuMed
International, Inc. to effect a one-for-six reverse stock split on the Common
Stock and declaring the advisability thereof.

        2. At the Combined Annual and Special Meeting of Stockholders held on
May 19, 1998, dully called and held in accordance with the provisions of Section
222 of the General Corporation Law of the State of Delaware, a majority of the
shares of the outstanding stock entitled to vote thereon, and a majority of the
outstanding stock of each class entitled to vote thereon as a class, were voted
in favor of such amendment in accordance with Section 242 of the General
Corporation Law of the State of Delaware.

        3. Article FOURTH of the Certificate of Incorporation of the Corporation
is hereby amended to read in its entirety as follows:

                  FOURTH. The total number of shares of all classes of capital
         stock which the Corporation shall have authority to issue is
         55,000,000 shares, divided into two classes as follows:

                  5,000,000 shares of Preferred Stock of the par value of $0.01
                  per share ("Preferred Stock"); and



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                  50,000,000 shares of Common Stock of the par value of $0.01
                  per share ("Common Stock").

         The designations, powers, preferences and rights, and the
qualifications, limitations or restrictions of the above classes of stock are as
follows:

                                   DIVISION I

                                 PREFERRED STOCK

         1. The board of directors is expressly authorized at any time, and from
time to time, to issue shares of Preferred Stock in one or more series, and for
such consideration as the board of directors may determine, with such voting
powers, full or limited but not to exceed one vote per share, or without voting
powers, and with such designations, preferences and relative, participating,
optional or other special rights, and qualifications, limitations or
restrictions thereof, as shall be stated in the resolution or resolutions
providing for the issue thereof, and as are not stated in this Certificate of
Incorporation, or any amendment thereto. All shares of any one series shall be
of equal rank and identical in all respects.

         2. No dividend shall be paid or declared on any particular series of
Preferred Stock unless dividends shall be paid or declared pro rata on all
shares of Preferred Stock at the time outstanding of each other series which
ranks equally as to dividends with such particular series.

         3. Unless and except to the extent otherwise required by law or
provided in the resolution or resolutions of the board of directors creating any
series of Preferred Stock pursuant to this Division I, the holders of the
Preferred Stock shall have no voting power with respect to any matter
whatsoever. In no event shall the Preferred Stock be entitled to more than one
vote in respect of each share of stock. Subject to the protective conditions or
restrictions of any outstanding series of Preferred Stock, any amendment to this
Certificate of Incorporation which shall increase or decrease the authorized
capital stock of any class or classes may be adopted by the affirmative vote of
the holders of a majority of the outstanding shares of the voting stock of the
Corporation.

         4. Shares of Preferred Stock redeemed, converted, exchanged, purchased,
retired or surrendered to the Corporation, or which have been issued and
reacquired in any manner, shall, upon compliance with any applicable provisions
of the GCL, have



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the status of authorized and unissued shares of Preferred Stock and may be
reissued by the board of directors as part of the series of which they were
originally a part or may be reclassified into and reissued as part of a new
series or as a part of any other series, all subject to the protective
conditions or restrictions of any outstanding series of Preferred Stock.

                                   DIVISION II

                                  COMMON STOCK

         1. DIVIDENDS. Subject to the preferential dividend rights, if any,
         applicable to shares of the Preferred Stock and subject to applicable
         requirements, if any, with respect to the setting aside of sums for
         purchase, retirement or sinking funds for the Preferred Stock, the
         holders of the Common Stock shall be entitled to receive to the extent
         permitted by law, such dividends as may be declared from time to time
         by the board of directors.

         2. LIQUIDATION. In the event of the voluntary or involuntary
         liquidation, dissolution, distribution of assets or winding up of the
         Corporation, after distribution in full of the preferential amounts, if
         any, to be distributed to the holders of shares of the Preferred Stock,
         holders of the Common Stock shall be entitled to receive all the
         remaining assets of the Corporation of whatever kind available for
         distribution to stockholders ratably in proportion to the number of
         shares of Common Stock held by them respectively.

         3. VOTING RIGHTS. Except as may be otherwise required by law or this
         Certificate of Incorporation, each holder of the Common Stock shall
         have one vote in respect of each share of stock held by him or her of
         record on the books of the Corporation on all matters voted upon by the
         stockholders.

         4. REVERSE STOCK SPLIT. Simultaneously with the effective date of this
         amendment (the "Effective Date"), each share of the Company's Common
         Stock, par value $0.01 per share, issued and outstanding immediately
         prior to the Effective Date (the "Old Common Stock") shall
         automatically and without any action on the part of the holder thereof
         be reclassified as and changed, pursuant to a reverse stock split, into
         one-sixth of a share of the Company's outstanding Common Stock, par
         value $0.01 per share (the "New Common Stock"), subject to the
         treatment of fractional share interests as described below. Each holder
         of a certificate or certificates which immediately prior to the
         Effective Date represented outstanding shares of Old Common Stock (the
         "Old Certificates," whether one or more) shall be entitled to receive
         upon surrender of such Old Certificates to the Company's Transfer Agent
         for cancellation, a certificate or certificates (the "New
         Certificates," whether one or more) representing the number of whole
         shares of the New Common Stock into which and for which the shares of
         the Old Common Stock formerly represented by such Old Certificates so
         surrendered, are reclassified under the terms hereof. From and after
         the Effective Date, Old Certificates shall represent only the right to
         receive New Certificates pursuant to the provisions hereof. No
         certificates or scrip representing fractional share interests in New
         Common Stock will be issued, and no such fractional share interest will
         entitle the holder thereof to vote, or to any rights of a shareholder
         of the Company. Any fraction of a share of New Common Stock to which
         the holder would otherwise be entitled will be adjusted upward to the
         nearest whole share. If more than one Old Certificate shall be
         surrendered at one time for the account of the same stockholder, the
         number of full shares of New Common Stock for which New Certificates
         shall be issued shall be computed on the basis of the aggregate number
         of shares represented by the Old Certificate so surrendered. In the
         event that the Company's Transfer Agent determines that a holder of Old
         Certificates has not tendered all his certificates for exchange, the
         Transfer Agent shall carry forward any fractional share until all
         certificates of that holder have been presented for exchange such that
         payment for fractional shares to any one person shall not exceed the
         value of one share. If any New Certificate is to be issued in a name
         other than that in which the Old Certificates surrendered for exchange
         are issued, the Old Certificates so surrendered shall be properly
         endorsed and otherwise in proper form for transfer, and the person or
         persons requesting such exchange shall affix any requisite stock
         transfer tax stamps to the Old Certificates surrendered, or provide
         funds for their purchase, or establish to the satisfaction of the
         Transfer Agent that such taxes are not payable. From and after the
         Effective Date the amount of capital represented by the shares of the
         New Common Stock into which and for which the shares of the Old Common
         Stock are reclassified under the terms hereof shall be the same as the
         amount of capital represented by the shares of Old Common Stock so
         reclassified, until thereafter reduced or increased in accordance with
         applicable law. 

                                  DIVISION III

                            ELIMINATION OF PREEMPTIVE
                                     RIGHTS

         No holder of stock of any class of the Corporation shall be entitled as
a matter of right to purchase or subscribe for any part of any unissued stock of
any class, or of any additional stock of any class or capital stock of the
Corporation, or of any bonds, certificates of indebtedness, debentures, or other
securities convertible into stock of the



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Corporation, now or hereafter authorized, but any such stock or other securities
convertible into stock may be issued and disposed of pursuant to resolution by
the board of directors to such persons, firms, corporations or associations and
upon such terms and for such consideration (not less than the par value or
stated value thereof) as the board of directors in the exercise of its
discretion may determine and as may be permitted by law without action by the
stockholders.


    IN WITNESS WHEREOF, we have signed this Certificate as of May 20, 1998.

                                        ACCUMED INTERNATIONAL, INC.



                                        By:    /s/ PAUL F. LAVALLEE
                                            ----------------------------------
                                               Paul F. Lavallee, Chairman, 
                                               President and Chief Executive 
                                               Officer 



ATTEST:


/s/ JOYCE L. WALLACH
- -----------------------------
Joyce L. Wallach
General Counsel and Secretary



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