On December 1, 2020, this report was posted online as an MMWR Early Release.
Carbapenem-resistant Acinetobacter baumannii (CRAB), an opportunistic pathogen primarily
associated with hospital-acquired infections, is an urgent public health threat (
1
). In health care facilities, CRAB readily contaminates the patient care environment
and health care providers’ hands, survives for extended periods on dry surfaces, and
can be spread by asymptomatically colonized persons; these factors make CRAB outbreaks
in acute care hospitals difficult to control (
2
,
3
). On May 28, 2020, a New Jersey hospital (hospital A) reported a cluster of CRAB
infections during a surge in patients hospitalized with coronavirus disease 2019 (COVID-19).
Hospital A and the New Jersey Department of Health (NJDOH) conducted an investigation,
and identified 34 patients with hospital-acquired multidrug-resistant CRAB infection
or colonization during February–July 2020, including 21 (62%) who were admitted to
two intensive care units (ICUs) dedicated to caring for COVID-19 patients. In late
March, increasing COVID-19–related hospitalizations led to shortages in personnel,
personal protective equipment (PPE), and medical equipment, resulting in changes to
conventional infection prevention and control (IPC) practices. In late May, hospital
A resumed normal operations, including standard IPC measures, as COVID-19 hospitalizations
decreased, lessening the impact of personnel and supply chain shortages on hospital
functions. CRAB cases subsequently returned to a pre–COVID-19 baseline of none to
two cases monthly. The occurrence of this cluster underscores the potential for multidrug-resistant
organisms (MDROs) to spread during events when standard hospital practices might be
disrupted; conventional IPC strategies should be reinstated as soon as capacity and
resources allow.
Hospital A is an urban, acute-care hospital in New Jersey with approximately 500 beds.
In May 2020, hospital A notified NJDOH of an increase in CRAB (A. baumannii with meropenem
minimum inhibitory concentration testing of ≥8 μg/mL) isolates from weekly ICU point
prevalence surveys (colonization screening) and from clinical infections. Hospital
A retrospectively reviewed microbiology records for CRAB isolated from inpatient specimens
since November 2019 and instituted prospective surveillance of laboratory results
to identify all CRAB isolates. Inpatients with hospital-acquired CRAB infection were
defined as those for whom CRAB was isolated from clinical or colonization screening
specimens collected on or after hospital day 3 and who had no earlier CRAB isolated
from specimens during the same hospitalization; incident CRAB was a patient‘s first
CRAB infection or colonization. Patients’ demographic characteristics, diagnoses,
treatments, disposition, and COVID-19 status were collected from medical records.
Diagnoses of CRAB infection or colonization were determined by infectious disease
specialists. NJDOH began an investigation to assess IPC practices at hospital A and
gather additional data. This activity was reviewed by CDC and was conducted consistent
with applicable federal law and CDC policy.*
During February–July 2020, 34 patients with hospital-acquired CRAB infection or colonization
were identified, including 28 (82%) whose incident CRAB infection or colonization
occurred during the facility’s surge in COVID-19 cases (March–June 2020) (Figure),
and 17 (50%) who had confirmed infection with SARS-CoV-2, the virus that causes COVID-19
(Table). Twenty (59%) incident cases were identified from clinical specimens and 14
(41%) through colonization screening. Median age of patients with CRAB infection was
55 years (interquartile range [IQR] = 48–64 years), and 28 patients (82%) were admitted
from home. No patients had prior documented CRAB infection or colonization. The median
interval from admission to incident CRAB infection was 19 days (IQR = 11–28 days).
Twenty-five (74%) patients were intubated and mechanically ventilated at the time
of specimen collection; those with COVID-19 were placed in a prone position. CRAB
infection was diagnosed in 20 (59%) of the 34 patients, including 14 (41%) with clinically
diagnosed CRAB ventilator-associated pneumonia, four of whom had bacteremia. At the
time of this report, 23 (68%) patients with CRAB infection had been discharged, 10
(29%) had died, and one remained hospitalized.
FIGURE
Number of admitted patients with COVID-19 (N = 846) and hospital-acquired carbapenem-resistant
Acinetobacter baumannii (CRAB)* (N = 34), by month — hospital A, New Jersey, February–July
2020
Abbreviation: COVID-19 = coronavirus disease 2019.
* CRAB infection or colonization.
The figure is a combination bar and line graph showing the number of admitted patients
with COVID-19 (N = 846)and hospital-acquired carbapenem-resistant Acinetobacter baumannii
(N = 34)at hospital A in New Jersey during February–July 2020, by month.
TABLE
Demographic and clinical characteristics of patients with carbapenem-resistant Acinetobacter
baumannii (CRAB) (N = 34) — hospital A, New Jersey, February–July 2020
Characteristics of patients with CRAB
No. (%) of patients
Age, median (IQR), yrs
55 (48–64)
Sex
Male
24 (71)
Female
10 (29)
Location before admission
Home
28 (82)
Skilled nursing facility
5 (15)
Long-term acute care hospital
1 (3)
Collection location of incident CRAB
Intensive care unit
25 (73)
Medical-surgical unit
5 (15)
Progressive care or step-down unit
4 (12)
Specimen source of incident CRAB
Respiratory (sputum, tracheal aspirate, or bronchial)
17 (50)
Axilla, groin, or rectal
6 (18)
Blood
5 (15)
Wound, bone, or other tissue
4 (12)
Urine
2 (5)
SARS-CoV-2 status
Positive
17 (50)
Negative
17 (50)
CRAB infection/colonization
Ventilator-associated pneumonia
10 (29)
Ventilator-associated pneumonia with bacteremia
4 (12)
Bacteremia
3 (9)
Bone or soft tissue infection
3 (9)
Colonization
14 (41)
Intubation/Mechanical ventilation at time of incident CRAB
Yes
25 (74)
No
7 (21)
Tracheostomy
Yes
8 (24)
No
26 (76)
Received respiratory therapy services
Yes
28 (82)
No
6 (18)
Disposition
Discharged/Transferred
23 (68)
Deceased
10 (29)
Remains hospitalized
1 (3)
Abbreviation: IQR = interquartile range
The multidrug-resistant CRAB definition (A. baumannii with documented resistance to
three or more classes of antibiotics) was applied to hospital clinical laboratory
antimicrobial susceptibility data for incident cases (
4
); all 34 met multidrug-resistant CRAB criteria. Thirty isolates were further evaluated
for carbapenemase genes through real-time polymerase chain reaction testing.
†
Twenty-six isolates harbored the gene encoding the OXA-23 carbapenemase. Among these
isolates, two from specimens collected in February and March harbored an additional
carbapenemase gene, encoding New Delhi metallo-β-lactamase (a gene rarely present
in CRAB isolates from patients in the United States), indicating that at least one
CRAB introduction occurred before the surge of COVID-19 cases (
5
). Four specimens were nonviable or did not yield CRAB growth.
During March–August 2020, hospital A admitted approximately 850 patients with COVID-19.
The number of cases peaked on April 9, with 36 new hospitalizations and 61% of the
inpatient census having a diagnosis of confirmed or suspected COVID-19. Pandemic-related
resource challenges necessitated intentional changes to IPC measures. Before the pandemic,
ventilator circuits and suctioning catheters were changed at specified intervals of
every 14 days and every 3 days, respectively, unless malfunctioning or visibly soiled.
To conserve equipment during the surge, the hospital’s respiratory therapy unit instituted
a policy to extend the use of ventilator circuits and suctioning catheters for individual
patients, replacing them only if they were visibly soiled or malfunctioning. To conserve
PPE, gown use as part of Contact Precautions§ was suspended for care of patients with
the endemic MDROs vancomycin-resistant Enterococcus spp. and methicillin-resistant
Staphylococcus aureus
¶ but was maintained for nonendemic MDROs such as CRAB. Gowns and gloves continued
to be used for all patients when indicated for Standard Precautions, including wearing
a gown when skin or clothing was likely to be exposed to blood or body fluids.** Anticipating
shortages, hospital A also adopted an extended-use PPE protocol for N95 respirators
and face shields. To prioritize personnel resources, activities of the MDRO workgroup,
a multidisciplinary team responsible for guiding IPC policy around MDRO prevention
efforts at hospital A, were suspended, along with biweekly bedside central venous
catheter and indwelling urinary catheter maintenance rounds. Routine audits of appropriate
PPE use, hand hygiene compliance, and environmental cleaning were also temporarily
discontinued.
Responding to COVID-19–related care needs also resulted in other unintentional changes
in standard practices for preventing the spread of MDROs and device-associated infections.
IPC leadership noted less frequent patient bathing with chlorhexidine gluconate and
a 43% reduction in ICU CRAB screening tests. These changes resulted from competing
clinical priorities, challenges in personnel availability, and an effort to minimize
staff members’ interaction time with patients. The facility experienced critical shortages
in personnel for nursing and environmental services, resulting from staff members’
illness, quarantine, and a surge in the number of patients with COVID-19. Nursing
resources were supplemented through agency and government entities; however, increased
patient-to-staff member ratios and the need to minimize patient contact might have
led to unidentified IPC breaches.
In early May, hospital A’s IPC leadership advised physicians, unit managers, and environmental
services of the CRAB cluster. Environmental services cleaned common areas and high-touch
surfaces of ICUs with bleach. Proper hand hygiene and PPE use were reinforced through
unit-based education, and compliance audits were restarted by mid-May. At the end
of May, environmental services terminally cleaned and disinfected the COVID-19 dedicated
ICUs and associated portable medical and respiratory equipment. IPC personnel and
unit leadership reinforced CRAB surveillance culture protocol adherence.
Public Health Response
In collaboration with hospital A, NJDOH investigated the cluster, including review
of laboratory data, patient information, IPC policies, and audit tools. NJDOH provided
technical guidance on IPC interventions and advised returning to normal operations
as soon as capacity allowed. IPC processes and interventions developed in collaboration
with NJDOH (adapted from CDC guidelines
††
) during a previous CRAB outbreak at hospital A helped establish metrics for baseline
incident case counts and adherence to IPC-related measures.
In June, NJDOH used New Jersey’s public health notification system
§§
to alert public health officials, health care providers, and infection preventionists
to the possible resurgence of MDROs in health care facilities facing COVID-19–related
resource limitations. In June 2020, hospital A reported fewer incident hospital-associated
CRAB cases, coinciding with a sharp decrease in COVID-19 hospitalizations (Figure).
This trend continued through July. In August, no incident hospital-associated CRAB
cases were reported, signaling a return to baseline numbers for the facility.
Discussion
The impact of the COVID-19 pandemic on the spread of antibiotic resistance in health
care settings has not been fully described. In response to a rapid increase in SARS-CoV-2
infections, many health care facilities adopted mitigation strategies to contend with
physical space limitations, constrained availability of personnel, shortages in PPE,
and a large number of critically ill patients. Recent single-facility reports from
the United States and Europe have described increased acquisition of MDROs among patients
hospitalized with COVID-19 (
6
–
8
). Hospital A experienced a large multidrug-resistant CRAB outbreak, primarily involving
ICU patients, which extended across multiple units during a surge in COVID-19 cases.
Outbreaks of CRAB have been well documented in acute care hospitals, particularly
among critically ill patients, and are often driven by factors that include breaches
in infection control and persistent environmental contamination (
3
,
9
). Containing these outbreaks often requires multiple, targeted interventions, including
increased surveillance, IPC audits, and environmental cleaning (
10
). During COVID-19 preparations and the ensuing surge in cases, decreased vigilance
for control of CRAB transmissions, including suspension of the MDRO workgroup, reduced
surveillance cultures, reduced personnel numbers (which decreased capacity for overall
auditing practices), and both intentional and unintentional changes in IPC practice
likely contributed to this CRAB cluster. The lack of audits made identifying and correcting
real-time IPC compliance issues difficult. Diminished colonization screening might
have resulted in a higher threshold for recognizing increasing incident hospital-acquired
CRAB cases. Reinstatement of conventional IPC strategies in ICUs, paired with enhanced
cleaning procedures and hand hygiene reeducation, likely contributed to the rapid
decline in cases.
The findings in this report are subject to at least three limitations. First, CRAB
can colonize persons for long periods, possibly leading to misclassification of some
cases present at admission as hospital-acquired cases; decreased ICU surveillance
testing might have contributed to this misclassification. Second, objective assessment
of hand hygiene, PPE use, and environmental cleaning during the surge in COVID-19
cases is difficult without routine audit data. Finally, whole genome sequencing to
determine the relatedness of isolates was not performed. Carbapenem resistance mechanism
testing indicated at least two introductions of CRAB, including one preceding the
surge. Whether OXA-23 CRAB spread into distinct patient populations (i.e., patients
with and without COVID-19) or these were different introductions remains unclear.
The COVID-19 pandemic has required hospitals to take unprecedented measures to maintain
continuity of patient care and protect health care personnel from infection. This
outbreak highlights that MDROs can spread rapidly in hospitals experiencing surges
in COVID-19 cases and cause serious infections in this setting. To reduce spread of
MDROs and the risk of infection for patients, hospitals should remain vigilant to
prevent and detect clusters of unusual infections and respond promptly when they are
detected. Facilities should prioritize continuity of core IPC practices (e.g., training
for and auditing of hand hygiene, PPE use, and environmental cleaning) to the greatest
extent possible during surges in hospitalizations and make every effort to return
to normal operating procedures as soon as capacity allows.
Summary
What is already known about this topic?
Carbapenem-resistant Acinetobacter baumannii (CRAB) causes health care–associated
infections that are challenging to contain and often linked to infection prevention
and control (IPC) breaches.
What is added by this report?
A New Jersey hospital reported a cluster of 34 CRAB cases that peaked during a surge
in COVID-19 hospitalizations. Strategies to preserve continuity of care led to deviations
in IPC practices; CRAB cases decreased when normal operations resumed.
What are the implications for public health practice?
Hospitals managing surges of patients with COVID-19 might be vulnerable to outbreaks
of multidrug-resistant organism (MDRO) infections. Maintaining IPC best practices
(e.g., MDRO surveillance and hand hygiene and environmental cleaning audits) to the
extent possible could mitigate spread.